INTRODUCTION: The optimal fixation method in total hip arthroplasty (THA) remains under debate. While cemented fixation has been associated with a lower risk of periprosthetic fracture, uncemented fixation predominates in Japan. This study aimed to compare early postoperative complications between cemented and uncemented fixation in elective THA using a nationwide inpatient database. MATERIALS AND METHODS: We identified 198,102 patients aged ≥ 65 years who underwent primary THA for osteoarthritis, osteonecrosis, or rheumatoid arthritis between December 2011 and March 2023 from the Japanese Diagnosis Procedure Combination (DPC) database. After 1:1 propensity score matching for age, sex, body mass index (BMI), and Charlson Comorbidity Index, 36,859 patients were included in each fixation cohort. Surgical and medical complications, and in-hospital mortality were compared using multivariate logistic regression. RESULTS: Cemented fixation was associated with a significantly lower risk of periprosthetic fracture (odds ratio [OR], 0.40; 95% confidence interval [CI], 0.30-0.53; p < 0.001), blood transfusion (OR, 0.76; 95% CI, 0.74-0.78; p < 0.001), and deep vein thrombosis (OR, 0.79; 95% CI, 0.74-0.84; p < 0.001). There were no statistically significant differences based on the predefined threshold (p < 0.001) in dislocation, infection, pulmonary embolism, cardiac or cerebrovascular events, or in-hospital mortality between fixation types, although a trend toward higher in-hospital mortality in the cemented group was observed. CONCLUSIONS: Cemented THA was associated with reduced rates of periprosthetic fracture, transfusion, and deep vein thrombosis without increasing other perioperative or medical complications. These findings suggest that cemented fixation may be associated with favorable short-term outcomes in selected patients.

PURPOSE: Smoking is a potentially modifiable risk factor for adverse outcomes after total hip arthroplasty (THA), but evidence on early postoperative complications in Asian populations remains limited. This study examined the association between smoking and early postoperative complications after elective THA using a nationwide inpatient database in Japan. METHODS: This retrospective cohort study analysed data from the Japanese Diagnosis Procedure Combination (DPC) database between December 2011 and March 2023. Patients undergoing elective primary THA for osteoarthritis, osteonecrosis of the femoral head, or rheumatoid arthritis were included. Smoking status was identified using administrative codes. One-to-one propensity score matching was used to balance baseline characteristics between smokers and non-smokers. Primary outcomes were early postoperative surgical complications, medical complications, and in-hospital mortality. Dose-dependent effects were assessed using the Brinkman Index, with heavy smoking defined as ≥ 600. RESULTS: After propensity score matching, 52,551 patients were included in each group. Smoking was associated with a higher risk of postoperative infection (odds ratio [OR] 1.31; 95% confidence interval [CI] 1.15-1.49; p < 0.001) and a lower likelihood of blood transfusion (OR 0.83; 95% CI 0.80-0.85; p < 0.001). No significant associations were observed with dislocation, periprosthetic fracture, wound dehiscence, reoperation, major medical complications, or in-hospital mortality. Heavy smoking (Brinkman Index ≥ 600) was not associated with postoperative complications. CONCLUSIONS: Smoking was associated with an increased risk of early postoperative infection following elective THA, but not with other major complications or in-hospital mortality. Smoking cessation should be considered an important component of perioperative optimisation.

Abstract Introduction The biomechanical effects of transverse and longitudinal capsulotomy on hip joint stability in arthroscopy have not been thoroughly investigated. This study used fresh-frozen cadavers to evaluate whether rotational stability and traction resistance differ between these two capsulotomy orientations. Methods Twelve hips from six fresh-frozen cadavers with intact femurs and pelvises were tested under three conditions: intact, post-capsulotomy, and post-repair. Two capsulotomy patterns were created: a 4 cm transverse capsulotomy assuming inter-portal capsulotomy and a longitudinal capsulotomy. Six hips underwent a transverse capsulotomy, and six underwent a longitudinal capsulotomy. The pelvis was fixed using a wooden plate, and an intramedullary nail was inserted into the femur. To assess rotational stability, internal and external torques of 5 Nm were applied at hip extension angles of 15° and 0°, and at hip flexion angles of 15°, 30°, 45°, and 60°. To evaluate traction resistance, a 200 N axial traction force was applied at flexion angles of 0°, 30°, 45°, and 60°. Results External rotation laxity increased significantly at all flexion angles following transverse capsulotomy, and only at 0° after longitudinal capsulotomy. The change in external rotation laxity was significantly greater in transverse capsulotomy at 15° of hip extension and 0° than longitudinal capsulotomies in post-capsulotomy compared to intact conditions. Internal rotation laxity did not significantly increase after the both types of capsulotomies and following capsular repair. Separation distance under traction force increased significantly after both types of capsulotomies. The separation distance with post-capsulotomy and post-repair at 0° flexion, and with post-repair at 30° flexion was significantly greater in the transverse group, but no significant differences observed in other positions or conditions. Conclusions This cadaveric study demonstrated that vertical (longitudinal) capsulotomy results in less external rotation and traction laxity - particularly at 15° extension and 0° flexion - than horizontal (transverse) capsulotomy. These differences were partially retained even after capsular repair. While standard repair improves overall joint stability, surgeons should note that the longitudinal incision tends to be more stable at lower levels of hip flexion.

Abstract Introduction Hip fractures are common in elderly individuals and contribute to significant morbidity and mortality. Low body mass index (BMI) is associated with osteoporosis and frailty, yet its impact on postoperative outcomes after hip fracture surgery remains unclear. Materials and methods We conducted a retrospective cohort study using Japan’s Diagnosis Procedure Combination (DPC) database. Patients aged ≥ 65 years undergoing surgery for hip fractures from April 2016 to March 2022 were included. Low BMI was defined as &lt; 17.0 kg/m ² , and &lt; 18.5 kg/m ² was used for sensitivity analyses. Patients &lt; 65 years or treated non-operatively were excluded. Primary outcomes included venous thromboembolism (VTE), pneumonia, urinary tract infection, cognitive dysfunction, in-hospital mortality, transfusion volume, and length of stay. Propensity score matching (1:1) was performed, followed by logistic regression. Results Of 474,293 patients identified, 63,761 matched pairs were analyzed. Compared to the non-low BMI group, the low BMI group had higher rates of urinary tract infection (3.6% vs. 3.0%; OR 1.203, 95% CI 1.131–1.280), pneumonia (5.3% vs. 3.0%; OR 1.850, 95% CI 1.746–1.961), and in-hospital mortality (3.4% vs. 1.6%; OR 2.233, 95% CI 2.068–2.411). Perioperative transfusion volume was higher in the low BMI group, while VTE was less frequent. Sensitivity analyses using &lt; 18.5 kg/m ² confirmed these findings. Conclusion Low BMI is associated with increased complications and mortality following hip fracture surgery in the elderly. These findings emphasize the prognostic relevance of BMI in perioperative risk assessment.

Abstract Introduction: Computer-assisted (CA) surgery is increasingly adopted in total hip arthroplasty (THA) to enhance implant positioning accuracy. However, robust evidence regarding its impact on postoperative complications compared with manual THA (M-THA) remains limited. This study evaluated the association between CA-THA and early postoperative complications using a large Japanese database. Materials and Methods: We analyzed 336,624 THA cases recorded in the Japanese Diagnosis Procedure Combination (DPC) database between December 2011 and March 2023. Of these, 242,067 underwent M-THA and 94,557 underwent CA-THA. One-to-one propensity score matching was performed to adjust for age, sex, body mass index, comorbidities, and diagnosis. Outcomes included surgical complications, medical complications, and in-hospital mortality. Results: After matching, 93,887 patient pairs were analyzed. Compared with M-THA, CA-THA was associated with lower odds of dislocation (OR 0.667, 95% CI 0.556–0.786, p  &lt; 0.001), infection (OR 0.763, 95% CI 0.687–0.848, p  &lt; 0.001), and re-operation (OR 0.822, 95% CI 0.732–0.922, p  &lt; 0.001), but higher odds of periprosthetic fracture (OR 1.301, 95% CI 1.118–1.514, p  &lt; 0.001). No significant differences were found in medical complications or mortality. Conclusions: In this nationwide cohort, CA-THA was associated with reduced risks of dislocation, infection, and reoperation, but an increased risk of periprosthetic fracture compared with M-THA. Further research should clarify optimal indications and refine patient selection criteria for CA-THA. In this nationwide cohort, CA-THA was associated with reduced risks of dislocation, infection, and reoperation, but an increased risk of periprosthetic fracture compared with M-THA. Further research should clarify optimal indications and refine patient selection criteria for CA-THA.

BACKGROUND: Hip fractures are a major cause of morbidity and mortality in the elderly. Cognitive impairment is known to be associated with poor postoperative outcomes, but its specific impact on complications following hip fracture surgery remains under-investigated in Japan. METHODS: This nationwide retrospective cohort study used the Diagnosis Procedure Combination (DPC) database to analyze patients aged ≥ 65 years who underwent surgical treatment for hip fractures between April 2016 and March 2022. Cognitive impairment was identified using ICD-10 codes. Propensity score matching (1:1) was performed using age, sex, body mass index, anesthesia type, fracture classification, surgical procedure, and Charlson Comorbidity Index. The primary outcomes were postoperative complications and in-hospital mortality; secondary outcomes included length of hospital stay and use of anti-osteoporotic medications. RESULTS: Of 474 293 eligible patients, 104 221 had cognitive impairment (22.0%). After matching, 96 982 patients were included in each group. Multivariate logistic regression showed that cognitive impairment was associated with higher risks of venous thromboembolism (odds ratio [OR]: 1.168, 95% confidence interval [CI]: 1.121-1.219), urinary tract infection (OR: 1.619, 95% CI: 1.543-1.699), and pneumonia (OR: 1.583, 95% CI: 1.510-1.661), all p < 0.0001. In-hospital mortality was similar between groups (2.0% vs. 1.9%). Patients with cognitive impairment had longer hospital stays (36.2 ± 29.9 vs. 34.6 ± 28.3 days) and lower rates of anti-osteoporotic medication use. CONCLUSION: Cognitive impairment is an independent risk factor for postoperative complications in elderly hip fracture patients. Tailored perioperative strategies are needed to improve outcomes in this high-risk group.

BACKGROUND: Obesity is associated with an increased risk of complications after total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA), particularly in Western populations. However, the effect of severe obesity (body mass index [BMI] ≥ 35 kg/m2) on postoperative complications in Japanese patients remains unclear. METHODS: We conducted a retrospective cohort study using Japan's Diagnosis Procedure Combination (DPC) database, including patients who underwent TKA or UKA between April 2016 and March 2023. Patients were classified into severely obese (BMI ≥35 kg/m2) and non-severely obese (BMI <35 kg/m2) groups. After 1:1 propensity score matching for age, sex, comorbidities, surgical method, and Charlson Comorbidity Index, postoperative complications were compared using chi-square tests and multivariate logistic regression analyses. RESULTS: A total of 7832 matched pairs were analyzed. The incidence of deep vein thrombosis (odds ratio [OR], 1.16; 95 % confidence interval [CI], 1.03-1.29; p = 0.011) and pulmonary embolism (OR, 1.79; 95 % CI, 1.03-3.10; p = 0.037) was significantly higher in the severely obese group. Simultaneous bilateral surgery was also an independent risk factor for venous thromboembolism (VTE). No significant differences were observed in surgical site infection, length of hospital stay, or transfusion volume between the two groups. CONCLUSIONS: Severe obesity and simultaneous bilateral surgery are independent risk factors for VTE following knee arthroplasty in Japanese patients. These findings highlight the need for careful perioperative management in this high-risk population.

Background and Objectives: Total hip arthroplasty (THA) following pelvic osteotomy for developmental dysplasia of the hip (DDH) is technically challenging due to altered acetabular morphology. This study aimed to compare radiographic cup position and perioperative characteristics of THA after three common pelvic osteotomies-periacetabular osteotomy (PAO), shelf procedure, and Chiari osteotomy-with primary THA in Crowe type I DDH. Methods: A retrospective review identified 25 hips that underwent conversion THA after pelvic osteotomy (PAO = 12, shelf = 8, Chiari = 5) and 25 primary THAs without prior osteotomy. One-to-one matching was performed based on sex (exact match), age (within 5 years), and BMI (within 2 kg/m2) without the use of propensity scores. Cup inclination, radiographic anteversion, center-edge (CE) angle, and cup height were measured on standardized anteroposterior radiographs (ICC = 0.91). Operative time, estimated blood loss, and use of bulk bone grafts or reinforcement rings were reviewed. One-way ANOVA with Dunnett's post hoc test and chi-square test were used for statistical comparison. Results: Cup inclination, anteversion, and CE angle did not differ significantly among groups. Cup height was significantly greater in the PAO group than in controls (29.0 mm vs. 21.8 mm; p = 0.0075), indicating a more proximal hip center. The Chiari and shelf groups showed upward trends, though not significant. Mean operative time tended to be longer after PAO (123 min vs. 93 min; p = 0.078). Bulk bone grafts and reinforcement rings were more frequently required in the PAO group (17%; p = 0.036 vs. control), and occasionally in Chiari cases, but not in shelf or control groups. Conclusions: THA after PAO is associated with higher cup placement and greater need for reconstructive devices, indicating increased technical complexity. In contrast, shelf and Chiari conversions more closely resemble primary THA. Preoperative planning should consider hip center translation and bone-stock restoration in post-osteotomy THA.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) and osteoarthritis (OA) are two common diagnoses for patients undergoing total hip arthroplasty (THA). The early surgical complications in THA for ONFH compared to OA are inconsistently reported. Therefore, this study aimed to evaluate whether THA for ONFH was associated with early postoperative complications in comparison to THA for OA using a large database of Japanese patients. METHODS: In this cohort study, using a Japanese national medical claims database on ONFH and OA patients undergoing THA from December 2011 to March 2023, we assessed the surgical-related complications, medical complications, and mortality during hospitalization after propensity score matching by age, sex, body mass index, and comorbidities. A total of 24,326 pairs of THAs for ONFH and OA were included. RESULTS: In the THA for ONFH group, the odds ratios for various complications were as follows: dislocation (1.3, 95% CI [confidence interval]: 1.1 to 1.6, P < 0.01), infection (1.0, 95% CI: 0.8 to 1.2, P = 0.94), periprosthetic fracture (1.0, 95% CI: 0.8 to 1.4, P = 0.86), nerve palsy during hospitalization (0.4, 95% CI: 0.2 to 0.9, P = 0.034), pneumonia (1.7, 95% CI: 1.1 to 2.5, P < 0.01), deep vein thrombosis (0.9, 95% CI: 0.8 to 1.0, P = 0.018), pulmonary embolism (1.5, 95% CI: 0.9 to 2.5, P = 0.14), cardiac events (0.7, 95% CI: 0.3 to 2.1, P = 0.55), cerebrovascular events (0.7, 95% CI: 0.5 to 1.0, P = 0.084), acute renal failure (1.4, 95% CI: 0.4 to 4.4, P = 0.56), and mortality during hospitalization (1.8, 95% CI: 1.3 to 2.4, P < 0.01). CONCLUSIONS: These findings contribute to identifying postoperative risks for ONFH patients and suggest that more attention should be paid to preoperative planning and postoperative care for ONFH patients.

BACKGROUND: Glucocorticoid use poses perioperative concerns in orthopaedic surgery, but its impact on postoperative outcomes following total knee arthroplasty (TKA) remains unclear. METHODS: This retrospective cohort study utilized the Japanese Diagnosis Procedure Combination (DPC) database to examine postoperative complications in patients undergoing TKA between April 2016 and March 2023. Patients receiving continuous glucocorticoid therapy (≥5 mg/day prednisolone equivalent) were identified and matched 1:1 with non-glucocorticoid users using propensity score matching based on age, sex, body mass index, anaesthesia type, simultaneous bilateral surgery, and Charlson Comorbidity Index. Postoperative complications, including pneumonia, surgical site infection, venous thromboembolism, cerebrovascular events, and in-hospital mortality, were compared. RESULTS: A total of 12 212 patients (6 106 per group) were analysed after matching. The glucocorticoid group showed significantly higher incidences of pneumonia (OR: 3.70, 95% CI: 1.89-7.26, p = 0.0001) and in-hospital mortality (OR: 3.59, 95% CI: 1.47-8.73, p = 0.005). No significant differences were observed in the incidence of deep vein thrombosis, pulmonary embolism, or surgical site infection, possibly due to short in-hospital observation and widespread use of prophylactic protocols. Male sex also emerged as an independent risk factor for mortality. CONCLUSIONS: Ongoing glucocorticoid use is associated with an increased risk of postoperative pneumonia and in-hospital mortality following TKA. These findings highlight the need for careful perioperative management in this high-risk population. Further prospective studies are warranted to assess long-term outcomes and clarify the effects of glucocorticoid dosage and duration.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) is a worldwide pandemic, and mortality increases in elderly patients with comorbidities. This study aims to examine the in-hospital complications and mortality for elderly patients with proximal femur fractures during the COVID-19 pandemic or countermeasure periods. MATERIALS AND METHODS: The proximal femur fractures undergoing surgery during the COVID-19 pandemic or countermeasure period were compared with the pre-pandemic in a Japanese national inpatient data. The assessed outcomes were the development of pneumonia, deep vein thrombosis (DVT), pulmonary embolism (PE), and mortality during hospitalization in two periods, and those for COVID-19-positive patients. RESULTS: A total of 284,922 proximal femur fractures aged over 65 years were included. In the COVID-19 pandemic period compared to the pre-pandemic, the odds of pneumonia, DVT, PE, and mortality decreased to 0.942 (95% confidence interval [CI]: 0.901 - 0.986, P = 0.0102) and 0.839 (95% CI: 0.745 - 0.946, P = 0.004), increased to 1.153 (95% CI: 1.112 - 1.195, P < 0.001), and 1.048 (95% CI: 0.982 - 1.118, P = 0.1554), respectively. For COVID-19 positivity at admission, the odds of PE increased significantly to 12.95 (95% CI: 8.795 - 19.06, P < 0.001). For COVID-19 positivity during hospitalization, the odds of pneumonia and mortality were increased to 2.896 (95% CI: 1.820 - 4.608, P < 0.001) and 6.303 (95% CI: 3.440 - 11.55, P < 0.001), respectively. CONCLUSION: These findings alert healthcare professionals and patients to the elevated complications, especially PE rate for proximal femoral fracture with COVID-19 positive.

BACKGROUND: Dialysis patients often develop advanced knee osteoarthritis, necessitating knee arthroplasty. Although total knee arthroplasty is commonly performed, limited data exist on perioperative complications among Japanese dialysis patients. This study uses a Japanese nationwide medical claims database to investigate the incidence of perioperative complications and mortality in dialysis versus nondialysis patients undergoing knee arthroplasty. METHODS: A retrospective analysis was conducted using data from a Japanese nationwide database (April 2016 to March 2023). Propensity score matching was used to balance confounding variables, including age, sex, body mass index, surgical procedures, and comorbidities. A 1:1 propensity score-matched cohort of 1,923 dialysis and 1,923 nondialysis patients was analyzed. Outcomes included in-hospital mortality, surgical site infections, and other complications. Multivariate logistic regression identified risk factors. RESULTS: Dialysis patients exhibited significantly higher in-hospital mortality and surgical site infection risks. The odds ratio (OR) for surgical site infection in dialysis patients was 2.17 (95% confidence interval: 1.31 to 3.61). The dialysis group demonstrated a significantly higher in-hospital mortality risk compared to the nondialysis group (P < 0.0001). No in-hospital deaths were observed among nondialysis patients postmatching, precluding the calculation of an OR. Bilateral simultaneous surgery emerged as an additional independent risk factor, with an OR of 9.94 (95% confidence interval: 1.95 to 50.74) in dialysis patients. CONCLUSIONS: This propensity score-matched study highlights significantly elevated surgical site infection and in-hospital mortality risks for dialysis patients undergoing knee arthroplasty. These findings underscore the necessity for careful perioperative management and the avoidance of high-risk procedures, such as bilateral simultaneous surgeries, in dialysis patients.

Dialysis patients who develop degenerative hip disease or femoral neck fractures may require total hip arthroplasty, and their comorbidities predispose them to complications. This study aimed to evaluate whether dialysis was associated with early postoperative complications using a large database of Japanese. In this cohort study, using the Japanese National Administrative Diagnosis Procedure Combination database on THA for patients on hemodialysis or not from December 2011 to March 2023, we assessed the surgical-related complications, medical complications, and mortality during hospitalization after propensity score matching by age, sex, BMI, and comorbidities. A total of 2,111 pairs of patients on hemodialysis and non-dialysis were included. In THA for patients on hemodialysis, the significant odds ratios for various complications were as follows: dislocation (2.616, 95% CI: 1.282 to 5.338, p < 0.01), reoperation (2.104, 95% CI: 1.222 to 3.623, p < 0.01), deep vein thrombosis (0.407, 95% CI: 0.286 to 0.579, p < 0.01), cerebrovascular events (4.426, 95% CI: 1.495 to 13.10, p < 0.01). These findings help identify postoperative THA risks for patients on dialysis, suggesting that more attention should be paid to preoperative planning and postoperative care.

INTRODUCTION: Type 2 diabetes is associated with an increased risk of fragility fractures, even in individuals with normal or high bone mineral density. However, the impact of type 2 diabetes on postoperative outcomes after hip fracture surgery in elderly Japanese patients remains unclear. This study evaluated the association between type 2 diabetes and postoperative complications, including in-hospital mortality, using a nationwide database in Japan. MATERIALS AND METHODS: A retrospective cohort study was conducted using the Diagnosis Procedure Combination (DPC) database from April 2016 to March 2022. Patients aged ≥ 65 years who underwent hip fracture surgery were included. Propensity score matching (1:1) was performed to adjust for confounders. Logistic regression analyses were used to assess associations between type 2 diabetes and outcomes. RESULTS: Of the 474,293 eligible patients included in this study, 18.5% were identified as having comorbid type 2 diabetes. Following 1:1 propensity score matching, the final analytic cohorts each comprised 83,283 patients. Although statistically significant, the presence of type 2 diabetes was associated with only modest increases in the risks of postoperative myocardial infarction (risk difference [RD]: 0.0007), cognitive dysfunction (RD: 0.0029), and in-hospital mortality (RD: 0.0045), with all comparisons yielding p-values of less than 0.0001. Additionally, the length of hospital stay was longer among patients with type 2 diabetes. CONCLUSIONS: Although the absolute risk differences were small, type 2 diabetes remains an independent risk factor for adverse postoperative outcomes following hip fracture surgery in elderly Japanese patients. Tailored perioperative strategies may help optimize outcomes in this vulnerable population.

INTRODUCTION: Total knee arthroplasty (TKA) is a widely used treatment for advanced knee osteoarthritis. While cemented fixation is the standard technique, cementless fixation has demonstrated comparable long-term outcomes. However, the association between cement use and postoperative complications, including venous thromboembolism and surgical site infections, remains unclear, particularly in Japanese patients. This study aimed to investigate the incidence of postoperative complications in cemented and cementless TKA using a nationwide database. METHODS: A nationwide cohort study was conducted using Japan's DPC database from April 2016 to March 2023. Patients who underwent TKA were identified, and postoperative complications, including deep vein thrombosis, pulmonary embolism, pneumonia, cerebrovascular events, postoperative cognitive dysfunction, and surgical site infection, were analyzed. One-to-one propensity score (PS) matching was performed based on age, sex, body mass index, type of anesthesia, simultaneous bilateral surgery, Charlson comorbidity index, and comorbidities to ensure comparability. Statistical analyses included χ² tests, Student's t-tests, and multivariate logistic regression analysis. RESULTS: A total of 228,595 patients met the eligibility criteria, with 21,906 matched pairs in the cemented and cementless groups after PS matching. The incidence of deep vein thrombosis (OR: 1.231, 95% CI: 1.151-1.316, p < 0.0001) and surgical site infection (OR: 1.716, 95% CI: 1.420-2.073, p < 0.0001) was significantly higher in the cemented group. No significant differences were observed in pulmonary embolism or other complications. CONCLUSION: Cement application was associated with an increased risk of deep vein thrombosis and surgical site infection. These findings suggest that careful perioperative management may be warranted in patients undergoing cemented TKA.

INTRODUCTION: Total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) are widely used to treat knee osteoarthritis. TKA significantly contributes to long-term pain relief and joint function improvement, while UKA offers faster recovery and reduced early complications. However, TKA and UKA complication risks, aside from conditions such as deep vein thrombosis, have not been thoroughly investigated. This study compares the in-hospital complication risks of TKA and UKA using a nationwide Japanese database. METHODS: A retrospective cohort study was conducted using data from the Japanese Diagnosis Procedure Combination (DPC) database, spanning from April 2016 to March 2023. A total of 259,319 knee arthroplasty cases (TKA: 228,595; UKA: 30,724) were analyzed. Propensity score matching (1:1) was used to adjust for age, sex, comorbidities, and surgical factors, resulting in 30,591 matched pairs. Multivariable logistic regression analyses assessed the risks of complications, including deep vein thrombosis, pulmonary embolism, and surgical site infections. RESULTS: Deep vein thrombosis is frequently observed as a complication with a high incidence rate. Even after propensity score matching, the incidence remained significantly higher in the TKA group (8.8%) compared with the UKA group (6.1%) (p < 0.0001). TKA was associated with significantly higher risks of deep vein thrombosis (odds ratio (OR): 1.467, 95% confidence interval (CI) 1.380-1.560, p < 0.0001), pulmonary embolism (OR: 1.709, 95% CI 1.182-2.470, p = 0.0044), and surgical site infection (OR: 1.512, 95% CI 1.277-1.790, p < 0.0001) compared with UKA. UKA showed lower risks of cognitive dysfunction, pneumonia, transfusion requirements, and shorter hospital stays. However, patients who underwent UKA had a higher risk of periprosthetic fractures. CONCLUSIONS: This study highlights the distinct risk profiles of TKA and UKA, emphasizing the need for tailored surgical decision-making. UKA offers advantages in reducing complications for specific patient populations. Strengthening prophylactic measures is crucial for effectively managing thromboembolic and infectious complications in patients undergoing TKA.

INTRODUCTION: Advances in pharmacological treatments have reduced joint deformities in rheumatoid arthritis (RA), leading to a decline in total knee arthroplasty (TKA) among RA patients. However, RA remains associated with higher risks of postoperative complications. This study compares postoperative complications during hospitalization in patients with RA and osteoarthritis (OA) undergoing TKA in Japan. METHODS: This retrospective cohort study utilized data from the Japanese Diagnosis Procedure Combination database from April 2016 to March 2023. Patients who underwent TKA were identified, and propensity score (PS) matching was performed to balance age, sex, body mass index, simultaneous surgeries, and comorbidities, resulting in 9048 matched pairs. Outcomes included periprosthetic joint infections (PJI), cognitive dysfunction, deep vein thrombosis (DVT), pulmonary embolism (PE), and periprosthetic fractures. Statistical analyses were conducted using multivariate logistic regression with a significance threshold of p < 0.01. RESULTS: RA patients had higher risks of PJI (odds ratio [OR]: 1.473, 95% CI: 1.134-1.912, p = 0.004) and postoperative cognitive dysfunction (OR: 1.721, 95% CI: 1.190-2.488, p = 0.004) compared to OA patients. In contrast, no significant differences were observed in the incidence of DVT, PE, or periprosthetic fractures. CONCLUSION: RA patients undergoing TKA are at increased risk of PJI and cognitive dysfunction, highlighting the need for tailored perioperative management. These findings provide important insights into optimizing outcomes for RA patients.

BACKGROUND: Biomechanical effect on hip joint stability between the transverse interportal capsulotomy and the longitudinal capsulotomy in arthroscopy has not been fully investigated. PURPOSE: To evaluate whether rotational stability and distraction resistance differ between the 2 capsulotomy directions using fresh-frozen cadavers. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve hips of 6 fresh-frozen cadavers, including intact femur and pelvis, were tested in 3 conditions: intact, capsulotomy, and repaired. Two capsulotomy patterns were made: a 4-cm transverse capsular resection based on a transverse interportal capsulotomy, and longitudinal capsulotomy. Six hips were transverse capsulotomy and 6 hips were longitudinal capsulotomy. The pelvis was fixed to a wooden plate, and the intramedullary nail was inserted into the femur. To evaluate rotational stability, internal and external torques of 5 N·m were applied at 15° of hip extension and 0°, 15°, 30°, 45°, and 60° of hip flexion, respectively. To test for distraction, the specimens were axially loaded from 0- to 150-N distraction forces at different flexion angles (0°, 30°, 45°, 60°). RESULTS: The external rotation laxity increased significantly after the transverse capsulotomy at all flexion angles and longitudinal capsulotomy only at 0°. The separation distance increased significantly after the transverse and longitudinal capsulotomies. The change in external rotation laxity was significantly greater in transverse capsulotomy at 15° of hip extension and 0° than longitudinal capsulotomies in unrepaired conditions compared with intact conditions. With distraction loads, the transverse capsulotomy resulted in a significantly greater separation distance than the longitudinal capsulotomy at all flexion angles with 100 N, and at 0° and 60° with 50 N. Significant differences were observed after capsular repaired compared with intact for external rotation angle at 15° extension and 0°, and separation distance at 60° flexion with 150 N and 100 N between capsulotomy directions. CONCLUSION: This cadaveric study demonstrated that the hips with the longitudinal capsulotomy resulted in less external rotation laxity, especially at 15° extension and 0°, and less distraction laxity compared with those with the transverse capsulotomy; and these differences remained after repair of capsulotomy. CLINICAL RELEVANCE: Either capsulotomy direction is effective if the capsular repair is performed properly because the standard capsular repair improves capsular stability. However, surgeons should note that the longitudinal incision tends to be more stable at lower levels of hip flexion.

BACKGROUND: Stress shielding (SS) after total hip arthroplasty (THA) leads to proximal femoral bone loss and increases the risk of complications such as implant loosening and periprosthetic fracture. While various low-stiffness stems have been developed to prevent SS, they often compromise mechanical stability. A novel femoral stem composed of Ti-33.6Nb-4Sn (TNS) alloy offers a gradually decreasing Young's modulus from proximal to distal regions, potentially improving load distribution and reducing SS. This study aimed to evaluate the mid-term clinical and radiographic outcomes of the TNS stem, with a particular focus on its effectiveness in suppressing SS. METHODS: A prospective clinical study was conducted involving 35 patients who underwent THA using the TNS stem, with a minimum follow-up of 7 years. Twenty-one patients with Ti6Al4V metaphyseal-filling stems served as controls. Clinical outcomes were assessed using Japanese Orthopaedic Association (JOA) scores, and radiographic SS was graded using Engh's classification and analyzed in Gruen zones. Inter-examiner reliability and statistical comparisons between groups were performed using appropriate tests. RESULTS: The TNS group showed significantly higher preoperative JOA scores than the control group, but no significant difference in final scores. Both groups demonstrated significant improvement postoperatively. Third-degree SS occurred in the TNS group, although the overall SS grade distribution was significantly lower than in the control group (p = 0.03). SS frequency was significantly reduced in Gruen Zones 2, 3, and 6 in the TNS group. CONCLUSIONS: The TNS stem demonstrated a significant reduction in SS progression compared to conventional titanium stems over a 7-year period, with comparable clinical outcomes. However, the occurrence of third-degree SS indicates that material optimization alone may be insufficient, highlighting the need for further design improvements.

BACKGROUND: To date, no study has compared simultaneous bilateral total hip arthroplasty (simBTHA) with staged BTHA (stgBTHA) using the anterolateral-supine approach (ALSA). This study compared the outcomes and cost-effectiveness of simBTHA and stgBTHA using ALSA. METHODS: This retrospective cohort study was conducted on patients who required bilateral ALSA THA at the time of their initial medical evaluation between August 2015 and January 2023. Patients were divided into two groups: simBTHA and stgBTHA. Demographic data, including age, sex, body mass index (BMI), and American Society of Anesthesiologists Physical Status (ASA-PS) scores, were collected. Operative outcomes such as surgical time, blood loss, autologous and allogeneic blood transfusions, and time to ambulation were compared. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) hip score, Japanese Orthopaedic Association Hip-disease Evaluation Questionnaire (JHEQ), and Forgotten Joint score-12 (FJS-12). Postoperative complications, revisions, readmissions, and mortality within 90 days were also recorded. The total cost, length of stay (LOS), and time interval between surgeries in the stgBTHA group were analyzed. RESULTS: A total of 129 patients were included: 104 in the simBTHA group and 25 in the stgBTHA group. The preoperative ASA-PS significantly differed between the two groups (P < 0.01), but other demographic data were not significantly different. The simBTHA group had significantly shorter surgical times (156 min) compared to the stgBTHA group (175 min) (p = 0.02). Blood loss was similar between the two groups (670 mL for simBTHA and 629 mL for stgBTHA). There were no significant differences in the time to ambulation, postoperative complications, or clinical outcomes between the two groups. However, the simBTHA group had a significantly lower total cost (83.2%, p < 0.01) and shorter LOS (20.5 days) compared to the stgBTHA group (30 days) (p < 0.01). No significant differences in complication rates, revisions, or readmissions were observed between the groups. CONCLUSIONS: SimBTHA with ALSA provides comparable clinical outcomes to stgBTHA while offering significant advantages in terms of reduced costs and shorter hospital stays. For patients with suitable health conditions, simBTHA is a preferable choice due to its faster recovery and greater cost-effectiveness.

Although the rate of total hip arthroplasty (THA) is declining among rheumatoid arthritis (RA) patients, the complex etiology of RA and associated immunomodulatory therapies may contribute to elevated risks of postoperative complications. This study aimed to evaluate in-hospital complications following THA in RA patients compared to osteoarthritis (OA) patients using a Japanese nationwide database. This retrospective study analyzed data from the Diagnosis Procedure Combination database, including THA patients between December 2011 and March 2023. The RA and OA groups were matched in a one-to-three ratio using propensity scores, considering factors such as age, sex, and comorbidities. Multivariate logistic regression was conducted to assess independent risk factors for complications. Among 353,465 patients, 3,977 underwent THA for RA and 298,326 for OA. After matching, 3,951 RA and 11,853 OA patients were included. RA was an independent risk factor for dislocation (OR: 2.783, 95% CI 1.641-4.720) and reoperation (OR: 2.254, 95% CI 1.687-3.013). No significant differences were observed in infection, periprosthetic fracture, venous thromboembolism, or mortality. RA patients undergoing THA are at higher risk for dislocation and reoperation. These findings emphasize the need for careful surgical planning and implementation to improve outcomes in RA patients.

INTRODUCTION: The risk of postoperative sequelae and in-hospital mortality in Japanese patients aged 90 years and older with hip fractures is unexplored. This study aims to use a comprehensive medical claims database in Japan to compare super-elderly patients aged 90 years and older with elderly aged 65-89 and clarify the risk of sequelae and in-hospital mortality in super-elderly patients. MATERIALS AND METHODS: We retrospectively analyzed the Diagnosis Procedure Combination (DPC) database for all of Japan from April 2016 to March 2022. Medical records from approximately 1100 DPC-related hospitals were provided with consistent consent during this period. In this study, we focused on super-elderly patients and examined the association with the risk of postoperative pneumonia, pulmonary embolism, myocardial infarction, urinary tract infection, acute renal dysfunction, subsequent cognitive dysfunction, and in-hospital mortality after one-to-one propensity score matching. RESULTS: After performing propensity score matching based on sex and comorbidities, 129,953 pairs of patients were identified. These pairs were compared to elderly and super-elderly patients. The results of this study showed that compared with hip fractures in the elderly, hip fractures in the super-elderly were associated with an increased risk of pneumonia, urinary tract infection, acute renal dysfunction, subsequent cognitive dysfunction, and in-hospital mortality after adjustment for confounders. The odds ratio of in-hospital mortality was 2.190 (95% CI 2.062-2.325). CONCLUSION: As it has been shown that super-elderly patients with hip fractures are at greater risk of respiratory and urinary tract infections and increased in-hospital mortality, careful attention should be required for perioperative management.

Background: Total hip arthroplasty (THA) is a widely used surgical intervention for hip osteoarthritis (HOA), with a rising demand driven by an aging population. Osteoporosis is associated with increased risks of bone loss and implant loosening after THA. While medications such as bisphosphonates and denosumab have shown promise in mitigating these risks, the impact of preoperative osteoporosis treatment on postoperative outcomes remains unclear. This study investigates the effect of preoperative osteoporosis treatment intervention on stress shielding and clinical outcomes in THA patients. Methods: This retrospective study included 107 patients who underwent cementless THA between April 2019 and March 2022. Patients under 60 years old, with a follow-up period of less than one year, or with prior hip surgery were excluded. Participants were divided into two groups: a treatment group receiving osteoporosis medication preoperatively and a non-treatment group. The outcomes assessed included preoperative bone metabolism markers, Bombelli classification, stress shielding grade, and clinical scores. Statistical analysis was performed using the Mann-Whitney U test and Chi-squared test, with significance set at p < 0.05. Results: The preoperative osteoporosis treatment intervention rate was 28.9%. Stress shielding grades were significantly lower in the treatment group (p = 0.001). However, no significant differences were observed in clinical scores one year postoperatively. Conclusion: Preoperative osteoporosis treatment significantly reduced stress shielding incidence, potentially influencing long-term outcomes by preventing bone atrophy-related pain and fractures. Preoperative bone density assessment and osteoporosis treatment intervention are recommended to improve THA outcomes. Larger studies are needed for further validation.

AIM: The effectiveness of early surgery in preventing complications in elderly Japanese hip fracture patients and the impact of weekend hospitalization need further investigation. The purpose of this study was to determine whether weekend hospitalization affects the incidence of various sequelae and death during hospitalization in elderly hip fracture patients using a comprehensive Japanese hip fracture case database. METHODS: We retrospectively analyzed the Japanese National Administrative DPC (Diagnosis Procedure Combination) database from April 2016 to March 2022. During this period, approximately 1100 DPC-affiliated hospitals consistently provided medical records with consent for the study. The study focused on weekend hospitalizations and investigated the associations with postoperative pneumonia, pulmonary embolism, myocardial infarction, urinary tract infection, acute renal dysfunction, dementia, and in-hospital mortality after propensity score matching. Owing to the large population size of the study, significance levels were strictly enforced, and a P-value < 0.001 was considered statistically significant. RESULTS: After performing propensity score matching based on age, sex, and comorbidities, 111 035 patient pairs were identified, comparing those admitted on weekends versus weekdays. The analysis showed no heightened risk of sequelae for those admitted during the weekend compared with weekdays. Additionally, there was a slight trend toward higher mortality risk during weekend hospital stays; however, the increase was insignificant, with a hazard ratio of 1.071 (95% confidence interval: 1.005-1.140, P = 0.03). CONCLUSION: The results of this study indicate that weekend hospitalization for elderly patients with hip fractures is not definitively associated with an increase in various sequelae or in-hospital mortality and that the importance of early surgery for elderly patients with hip fractures may be recognized and promoted in Japan. Geriatr Gerontol Int 2024; ••: ••-••.

BACKGROUND: This study investigated the impact of total knee arthroplasty (TKA) on the alignment of the ankle joint, focusing on changes in coronal alignment of both ankles. METHODS: This retrospective study, conducted at our hospital, included 64 patients older than 70 years who underwent TKA for varus knee osteoarthritis (OA). Using full-length standing radiographs of both lower extremities taken preoperatively and 6 months postoperatively, we assessed ankle OA grading based on the Takakura-Tanaka classification and measured mechanical hip-knee-ankle (mHKA) and the tibiotalar angle (TTA) on both the surgical and contralateral side. Additionally, we examined the impact of ankle OA on postoperative clinical scores, the Knee injury and Osteoarthritis Outcome Score, following TKA. RESULTS: Based on the classification, ankle OA stage 2 or higher was present in 13 cases on the surgical side and 13 cases on the contralateral side. On the surgical side, mHKA changed from 12.2 to 1.8 degrees varus (P < .001) and TTA from 1.7 to 1.0 degrees varus (P = .002). On the contralateral side, mHKA changed from 4.0 to 5.4 degrees varus (P = .04), and TTA from 2.7 to 3.0 degrees varus (P < .001). In ankle OA stage 2 or higher patients, contralateral TTA changed from 5.2 to 6.5 degrees varus (P < .001) and unchanged in stage 1 patients. Ankle OA stage 2 or higher patients had worse ADL outcomes than stage 1 patients (score: 67.2 and 78.3, respectively, P = .03). CONCLUSION: This study suggests an apparent interrelationship between knee and ankle OA and the potential negative influence of TKA on ankle OA.

Orthopedic implants such as arthroplasty prostheses, fracture plates, and intramedullary nails often use materials like Ti6Al4V alloy and commercially pure titanium (CP-Ti), which have Young's modulus significantly higher than that of human cortical bone, potentially causing stress shielding and inhibiting effective fracture healing. TiNbSn alloy, a β-type titanium alloy with a lower Young's modulus (40-49 GPa), has shown promise in reducing stress shielding and enhancing bone healing by promoting effective load sharing with bone. This study used 5-hole plates made from TiNbSn alloy and CP-Ti to investigate their effects on bone healing in a rat femoral fracture model. Micro-CT analysis and mechanical testing were performed six weeks postoperatively to assess bone healing. Additionally, Finite element method (FEM) analysis was employed to evaluate stress shielding and interfragmentary movement (IFM) at the fracture site. Micro-CT analysis revealed significantly higher bone volume and mineral density in the TiNbSn group than in the CP-Ti group. Mechanical testing showed increased maximum load and stiffness in the TiNbSn group (77.2 ± 10.0 N for the TiNbSn alloy plate group versus 53.3 ± 8.5 N for the CP-Ti group (p = 0.002)). FEM analysis indicated that TiNbSn plates reduced stress shielding and allowed for greater displacement and strain, promoting IFM conducive to bone healing. The findings suggest that TiNbSn alloy plates are more effective than CP-Ti plates in promoting bone healing by reducing stress shielding and enhancing IFM. The lower Young's modulus of TiNbSn allows better load distribution, facilitating bone regeneration and strengthening at the fracture site.

OBJECTIVES: Rheumatoid arthritis (RA) is a common autoimmune disorder characterized by chronic inflammation and periarticular bone loss, leading to systemic osteoporosis and heightened fracture susceptibility, especially hip fractures among the elderly. This study aimed to evaluate the outcomes and complications associated with hip fractures in patients with RA relative to those without RA. METHODS: Using the Japanese National Administrative Diagnosis Procedure Combination (DPC) database, we examined cases of femoral neck fractures from April 2016 to March 2023. After one to three propensity score matching for age, sex, and complications, we examined the association between RA, complications, and mortality during hospitalization in elderly patients with hip fractures. RESULTS: The findings revealed that elderly Japanese RA patients with hip fractures had significantly higher complications of pneumonia than elderly hip fracture patients without RA, with a ratio of 1.232 (95% CI: 1.065-1.426, p=0.0056), and pulmonary embolism, with a ratio of 1.155 (95% CI: 1.036-1.287, p=0.009) in multivariate logistic regression analyses. Although not significantly elevated, it also found a trend toward higher mortality during hospitalization, with a ratio of 1.179 (95% CI: 0.973-1.429, p=0.096). CONCLUSIONS: A substantial study based on the Japanese DPC database revealed a significant association between RA and increased complications, including pneumonia and pulmonary embolism. On the other hand, there was a nonsignificant but higher trend for risk of mortality during hospitalization for hip fracture in elderly RA patients. Implementing preventive strategies is essential to minimizing complications in the treatment of hip fractures in patients with RA.

BACKGROUND: In this study, we compared postoperative leg length discrepancy (LLD) after total hip arthroplasty using the anterolateral-supine approach (ALSA THA) with or without medial iliofemoral ligament (mILFL) preservation and examined the effect of the remaining mILFL on postoperative LLD. METHODS: This was a single-center, retrospective case control study. Unilateral primary THA with a preoperative LLD <15 mm, in which the contralateral side was intact, was included. After ALSA THA, we compared the absolute values of postoperative LLDs and examined the ratio of postoperative LLD >5 mm with and without mILFL preservation. Demographic data, clinical scores, and operative data were collected. Statistical significance was set at p < 0.05. RESULTS: We included 341 hips (preservation group: 283 hips; resection group: 58 hips). The mean (range) absolute values of the postoperative LLDs were 2.3 (0-15.9) mm and 3.4 (0-14.8) mm, respectively. There was no significant difference between the two groups (p = 0.36). The proportion of postoperative LLD >5 mm differed significantly between the groups (4.4 % and 20.0 %, respectively; p < 0.01). Multiple logistic regression analysis showed that resection of the mILFL was the only significant factor that caused excessive leg lengthening (odds ratio, 5.28; 95 % confidence interval, 2.12-13.10, p < 0.01). Significant differences were reported in surgical time (81 (38-132) and 96 (54-157), respectively; p < 0.01) and intraoperative blood loss (297 (50-1170) and 388 (100-1150), respectively; p < 0.01). However, no significant differences in clinical scores, dislocation (including instability), or reoperation rates were observed between the two groups. CONCLUSION: In patients with a preoperative LLD <15 mm, preserving the mILFL in ALSA THA avoids excessive leg lengthening and may lead to shorter LLD without any difficulties.

INTRODUCTION: The efficacy of early surgery in preventing complications among Japanese elderly patients with hip fractures requires further investigation. This study aims to use a comprehensive Japanese hip fracture case database to determine whether surgery within the day of admission and the following day reduces the incidence of complications and mortality during hospitalization in elderly hip fracture patients. MATERIALS AND METHODS: We retrospectively analyzed the Japanese National Administrative DPC (Diagnosis Procedure Combination) database from April 2016 to March 2022. Approximately 1100 DPC-affiliated hospitals consistently provided medical records with consent for research. The study investigated the association between postoperative pneumonia, deep vein thrombosis, pulmonary embolism, and mortality during hospitalization after propensity score matching, focusing on surgeries conducted on the day of admission and the following day. RESULTS: After one-to-one propensity score matching for age, gender, and comorbidity, we identified 146,441 pairs of patients who underwent surgery either within the day of admission and the following day or after the third day of admission. Surgery on the third day or later was independently associated with increased risks of pneumonia, deep vein thrombosis, pulmonary embolism, and mortality during hospitalization with risk ratios of 1.367 (95% CI 1.307-1.426), 1.328 (95% CI 1.169-1.508), 1.338 (95% CI 1.289-1.388), and 1.167 (95% CI 1.103-1.234), respectively. CONCLUSION: A comprehensive study of elderly Japanese patients with hip fractures in the DPC database showed that surgery on admission and the following day is crucial for preventing complications like pneumonia, deep vein thrombosis, pulmonary embolism, and mortality during hospitalization.

BACKGROUND: The global increase in femoral neck fractures due to aging and osteoporosis is a major clinical challenge. The debate on the optimal surgical intervention for femoral neck fractures remains unresolved. This large-scale study explores femoral neck fractures among the elderly, focusing on the comparative outcomes of Total Hip Arthroplasty (THA) versus Bipolar Hemiarthroplasty (BHA) in Japanese patients. METHODS: Using the Japanese National Administrative Diagnosis Procedure Combination (DPC) database, we studied cases of femoral neck fracture from April 2016 to March 2023, and after propensity score matching by age, sex, and comorbidities, we examined the association between THA, complications, and clinical outcomes, and the usefulness of THA for elderly patients with femoral neck fracture. RESULTS: One-to-one propensity score matching identified 7741 pairs of THA and BHA cases. There was no difference in length of stay between the THA and BHA groups. Significantly more blood transfusions were required in the THA group. There was no significant difference in mortality between the THA and BHA groups, but there was a reduced risk of pneumonia in the THA group, with a ratio of 0.547 (95% CI: 0.418-0.715). On the other hand, the THA group had a higher risk of pulmonary embolism, with a ratio of 1.607 (95% CI: 1.379-1.874). The THA group shows improved discharge rates directly home from the facility where the operation was performed, with a ratio of 1.798 (95% CI: 1.675-1.929). CONCLUSION: The findings of this research indicate that THA is more effective than BHA in enabling elderly Japanese patients with femoral neck fractures to be discharged directly home and in preventing pneumonia, despite concerns about pulmonary embolism. These findings suggest that THA may improve functional prognosis in elderly patients with femoral neck fractures, although there is a trade-off with an increased risk of pulmonary embolism.

Abstract Purpose The acetabular coverage in osteonecrosis of the femoral head (ONFH) affects the need for surgical intervention, and the collapse of the femoral head remains unclear. This study aimed to evaluate the relation between the acetabular coverage and the need for surgical treatment and femoral head collapse. Methods The study included 158 patients with 252 hips with glucocorticoid administration and idiopathic ONHF without osteoarthritis changes. The mean age at the first visit was 45.2 years, and the mean follow-up period was 92.2 months. All ONFH hips were subsequently divided into two groups: those needing surgical intervention and those without surgery. Additionally, it divided 167 initially non-collapsed hips into those that either later collapsed or not. Radiographic parameters with the centre-edge angle, acetabular roof obliquity, sharp angle, and necrotic location, following the guidelines of the Japanese Investigation Committee, were evaluated. Results There were no significant differences in radiographic parameters between the 106 hips that underwent surgery and the 146 hips without surgery. Among the 167 hips without initial collapse, 91 eventually collapsed while 76 did not; their radiographic findings have no significant differences. The necrotic locations were significantly larger in hips requiring surgical intervention or femoral head collapse. Furthermore, 21.8% (55 out of 252 hips) had acetabular dysplasia, which did not significantly correlate with the necessity for surgical treatment or the incidence of femoral head collapse. Conclusions Acetabular coverage has little effect on the necessity for surgical treatment and femoral head collapse in ONFH patients over a long-term follow-up.

Background and Objectives: The conventional posterior approach in the lateral decubitus position is widely used for femoral neck fractures in femoral hemiarthroplasty. Postoperative dislocation is the major problem with this approach. The conjoined tendon-preserving posterior (CPP) approach is a less invasive surgical approach than the conventional posterior approach to the hip, maintains posterior stability, and preserves short external rotators and joint capsules. However, the mention was required to avoid muscle damage and whether muscle damage affects postoperative dislocation or not. The current study aimed to evaluate the clinical results of the CPP approach in hemiarthroplasty for femoral neck fractures and identify muscle damage risk factors. Materials and Methods: This study was a retrospective cohort study and included 170 hips in 168 patients. The mean age at the operation was 81.2 years. The preservation rate of the internal obturator muscle and gemellus inferior muscle and factors related to intraoperative short rotator muscle injury were investigated retrospectively. The postoperative complications and the relation between muscle damage and postoperative dislocation were investigated. Results: In the four hips (2.3%) with the obturator internus muscle damage, thirty-eight hips (22.4%) with gemellus inferior muscle damage were detected; in the muscle-damaged cases, the high body mass index (BMI) was significantly higher. The complication occurred in four hips (2.3%), including postoperative posterior dislocation in one hip without muscle damage (0.6%). Postoperative infection occurred in one hip (0.6%), and peroneal or sciatic nerve paralysis was suspected in two hips (1.1%). Conclusions: Compared to the conventional posterior approach in previous reports, the CPP approach reduces postoperative dislocation. A higher BMI is a risk factor for muscle damage, and the gemellus inferior muscle damage has no effect on postoperative dislocation. The CPP approach for BHA appeared to be an effective treatment method.

PURPOSE: The conjoined external rotator tendon (CERT), composed of the tendons of the gemellus superior, obturator internus (OI), and gemellus inferior muscles, stabilizes the hip joint. The study investigates the clinical and radiological effects of the CERT release during anterolateral-supine approach (ALSA) total hip arthroplasty (THA). METHODS: A cohort of 60 patients who underwent ALSA THA was examined. Pre- and post-operative muscle width, muscle strength, and radiological data were compared between the CERT-detached and preserved groups. In addition, Clinical assessments were performed using the Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire and the short-form 36 questionnaires. RESULTS: 58.3% had CERT detached, resulting in radiological atrophy of the OI muscle. Despite this, hip flexion, extension, and abduction muscle strength significantly improved at 6 months post-surgery. The detached CERT did not substantially affect patient-reported outcome measures, including pain and daily activities, within the 6-month follow-up. DISCUSSION: The study suggests that while CERT detachment can lead to muscle atrophy, it has a limited impact on muscle strength and patient-reported outcome measures, indicating the muscle's potential redundancy. Preserving the CERT might enhance stability and prevent atrophy but could increase the risk of complications. CERT release is recommended when femur exposure is inadequate.

An early surgery for older adult patients with hip fractures is recommended to avoid perioperative complications in existing clinical guidelines. Few studies have analyzed only transtrochanteric fractures. The purpose of this study was to assess whether surgery within two days of admission reduces the incidence of pneumonia, deep vein thrombosis, pulmonary embolism, pressure ulcers, and mortality during hospitalization in patients with older adult transtrochanteric femur fractures. In this retrospective study, we used the Japanese National Administrative DPC (Diagnosis Procedure Combination) database that covers April 2016 to March 2022. Transtrochanteric femur fracture was included in patients aged 65 years or older who underwent surgery. The perioperative complications with pneumonia, deep vein thrombosis, pulmonary embolism, pressure ulcers, and mortality during hospitalization were assessed after propensity score matching, focusing on surgeries conducted within two days of admission. After one-to-one propensity score matching for age, sex, and comorbidity, we identified 79,649 pairs of patients who underwent surgery either within two days or after the third day of admission. Surgery delayed beyond two days was independently associated with increased pneumonia, pulmonary embolism, pressure ulcers, and mortality during hospitalization with risk ratios of 1.335 (95% CI: 1.256-1.418, p < 0.0001), 1.287 (95% CI: 1.225-1.351, p < 0.0001), 1.229 (95% CI: 1.094-1.380, p < 0.0001), and 1.063 (95% CI: 0.978-1.155, p = 0.0035), respectively. Surgery within two days of admission for transtrochanteric femur fracture effectively prevents perioperative complications and reduces mortality during hospitalization.

A new beta TiNbSn alloy with a low Young's modulus of approximately 40 GPa has been developed to resolve the stress shielding by Young's modulus divergence. In this study, the efficacy of TiNbSn alloy locking plates on bone repair is compared to that of commercially pure titanium (CP-Ti). The TiNbSn alloy and CP-Ti, which have Young's moduli of 49.1 GPa and 107 GPa, respectively, were compared. Male Japanese white rabbits were anesthetized, and osteotomy and osteosynthesis with locking plates were performed on the right tibia. The bone repair was assessed using micro-computed tomography (CT), histomorphometry, immunohistochemistry, and mechanical testing. Micro-CT, histomorphometry, immunohistochemistry, and mechanical testing were performed four weeks after osteotomy. Six weeks after surgery, micro-CT and mechanical testing were performed. Micro-CT analysis at four weeks after surgery showed that the intramedullary fracture callus in the TiNbSn alloy group had more bone volume and numerous bridging structures compared to the CP-Ti group (CP-Ti vs. TiNbSn alloy, 34.3 ± 13.1 mm3 vs. 61.3 ± 19.6 mm3, p = 0.02; mean ± standard deviation). At four weeks post-osteotomy, the healed tibia showed significantly higher strength in the TiNbSn alloy group compared with CP-Ti (CP-Ti vs. TiNbSn alloy, 81.3 ± 31.2 N vs. 133.7 ± 46.6 N, p = 0.04). TiNbSn alloy locking plates had a more positive impact on bone formation and bone strength restoration than the CP-Ti locking plates during the early phase of bone healing.

BACKGROUND: The difference between Young's moduli of the femur and the stem causes stress shielding (SS). TiNbSn (TNS) stem has a low Young's modulus and strength with gradient functional properties during the change in elastic modulus with heat treatment. The aim of this study was to investigate the inhibitory effect of TNS stems on SS and their clinical outcomes compared to conventional stems. METHODS: This study was a clinical trial. Primary THA was performed using a TNS stem from April 2016 to September 2017 for patients in the TNS group. Unilateral THA was performed using a Ti6Al4V alloy stem from January 2007 to February 2011 for patients in the control group. The TNS and Ti6Al4V stems were matched in shape. Radiographs were obtained at the 1- and 3-year follow-ups. Two surgeons independently checked the SS grade and appearance of cortical hypertrophy (CH). The Japanese Orthopaedic Association (JOA) scores before and 1 year after surgery were assessed as clinical scores. RESULTS: None of the patients in the TNS group had grade 3 or 4 SS. In contrast, in the control group, 24% and 40% of patients had grade 3 and 4 SS at the 1- and 3-year follow-ups, respectively. The SS grade was lower in the TNS group than in the control group at the 1- and 3-year follow-ups (p < 0.001). The frequencies of CH in both groups were no significant difference at the 1- and 3-year follow-ups. The JOA scores of the TNS group significantly improved at 1 year after surgery and were comparable to control group. CONCLUSION: The TNS stem reduced SS at 1 and 3 years after THA compared to the proximal-engaging cementless stem, although the shapes of the stems matched. The TNS stem could reduce SS, stem loosening, and periprosthetic fractures. TRIAL REGISTRATION: Current Controlled Trials. ISRCTN21241251. https://www.isrctn.com/search?q=21241251 . The date of registration was October 26, 2021. Retrospectively registered.

This study examined the association between developmental dysplasia of the hip (DDH) and disease-associated loci in a Japanese cohort. A genome-wide association study (GWAS) of 238 Japanese patients with DDH and 2044 healthy individuals was performed. As a replicate, GWAS was also conducted on the UK Biobank data with 3315 cases and matched 74,038 controls. Gene set enrichment analyses (GSEAs) of both the genetics and transcriptome of DDH were performed. Transcriptome analysis of cartilage specimens from DDH-associated osteoarthritis and femoral neck fractures was performed as a control. Most of the lead variants were very low-frequency ones in the UK, and variants in the Japanese GWAS could not be replicated with the UK GWAS. We assigned DDH-related candidate variants to 42 and 81 genes from the Japanese and UK GWASs, respectively, using functional mapping and annotation. GSEA of gene ontology, disease ontology, and canonical pathways identified the most enriched pathway to be the ferroptosis signaling pathway, both in the Japanese gene set as well as the Japanese and UK merged set. Transcriptome GSEA also identified significant downregulation of genes in the ferroptosis signaling pathway. Thus, the ferroptosis signaling pathway may be associated with the pathogenic mechanism of DDH.

<jats:p> Few randomized trials have shown how the placement of a palmar locking plate affects outcomes. The purpose of this study was to compare clinical and radiological outcomes of fixation using locking plates with different concepts for placement relative to the watershed line in a prospective randomized trial. Sixty-four patients with a displaced distal radius fracture were divided into two groups according to the plates used for fixation: distal-type (AcuLoc<jats:sup>TM</jats:sup>, Group A) and proximal-type (VariAx<jats:sup>TM</jats:sup>, Group V). Wrist function including the range of motion and grip strength was compared at 1, 2, 3 and 6 months postoperatively. Loss of reduction was assessed radiologically. Both groups demonstrated overall satisfactory function at 6 months with no significant difference found between the groups. Minimal loss of reduction was demonstrated in both groups. Internal fixation using the palmar locking plates with two different placements provided satisfactory outcomes at 6-month follow-up, but our results indicate that plates placed distal to the watershed line may delay recovery of wrist motion. </jats:p>