OBJECTIVES: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) offers quantitative insights into synovitis by evaluating vascular changes. However, its potential to predict progressive bone destruction in rheumatoid arthritis (RA) remains unclear. This study aimed to identify DCE-MRI parameters that predict joint deformity progression and establish their clinical relevance. METHODS: This prospective cohort study included 24 RA patients undergoing DCE-MRI at baseline and after treatment initiation. Radiographic progression was assessed using the modified total Sharp score 1 year after the second DCE-MRI. Histogram analysis of the enhanced synovium was performed using a mathematical model to derive parameters, including β (washout rate) and signal enhancement ratio (SER). The differences in mathematical parameters between the groups were statistically evaluated using the Mann-Whitney U test. RESULTS: Clinical factors, including 28-joint disease activity score (DAS28)-erythrocyte sedimentation rate and visual analog scale scores, were elevated in the progression group ( p = 0.001 and p = 0.02, respectively). Patients with progressive bone destruction exhibited significantly higher posttreatment β and SER values ( p = 0.023 and p = 0.03, respectively), reflecting delayed-phase curve patterns associated with angiogenesis and increased vascular permeability. No significant differences in the volume of enhanced synovium or Rheumatoid Arthritis Magnetic Resonance Imaging Score synovitis scores were observed. There was no difference between the groups in the change in clinical parameters. CONCLUSION: Posttreatment β and SER values derived from DCE-MRI may serve as predictive markers of future bone destruction in RA. These findings highlight the potential of DCE-MRI in guiding therapeutic decisions. Future studies with larger cohorts and automated analysis methods are warranted to validate these results and enhance clinical feasibility.

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.

This study investigated whether a composite consisting of octacalcium phosphate (OCP) and porous poly(lactide-co-glycolide) (PLGA) involving recombinant stromal-derived factor-1 (SDF-1) can be used to repair severe orthopedic bone defects. Four experiments were conducted: 1) analysis of loading and release of a model protein for SDF-1, cytochrome c for OCP/PLGA; 2) observation of the effect of SDF-1 on migration of mesenchymal stem cells (MSCs) in the presence of OCP/PLGA in vitro; 3) histomorphometry and immunohistochemistry of bone regeneration of OCP/PLGA/SDF-1 by its implantation into a 3 mm diameter rat femoral transcortical defect for 4 weeks; and 4) micro-CT analysis of the tissue and Fourier transform infrared (FTIR) spectroscopy using undecalcified specimens. The binding effects of cytochrome c and SDF-1 on 40 wt % OCP/PLGA were compared using OCP/PLGA with SDF-1 or cytochrome c prepared under saturated (S) and supersaturated (SS) conditions, containing low or high calcium and phosphate ion concentrations. The loading rates were higher in OCP/PLGA regardless of SS conditions than in PLGA, while the release rate was higher in OCP/PLGA loaded under SS conditions throughout the time, up to 168 h. MSC migration was most enhanced in the OCP/PLGA and loaded under SS conditions for up to 48 h. Bone regeneration was enhanced in OCP/PLGA loaded under SS conditions followed by S conditions and no SDF-1 loading of the OCP/PLGA for up to 4 weeks. Micro-CT and FTIR analyses suggested the material's biodegradation and new bone replacement, which was consistent with the histomorphometry. Osteocalcin-positive cells, tartrate-resistant acid phosphatase-positive cells, and C-X-C motif chemokine receptor type 4 positive cells were localized around the OCP/PLGA under SS conditions, corresponding to higher resorption of the OCP granules. The results suggest that OCP/PLGA involving SDF-1 may repair severe orthopedic bone defects.

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.

BACKGROUND: Magnetic resonance imaging (MRI), utilizing fat-saturated T2-weighted and short-tau inversion recovery sequences, is essential for the early diagnosis and monitoring of axial spondyloarthritis (axSpA). Recently, the European Society of Musculoskeletal Radiology proposed recommendations for the standardization of MRI findings for axSpA. However, the predictive value of specific MRI findings for spinal ankylosis progression remains unclear. This study investigates whether baseline MRI findings correlate with the progression of spinal ankylosis observed on radiographs over a 2-year period. METHODS: Twenty-six axSpA patients who met Assessment of SpondyloArthritis International Society criteria and underwent baseline and 2-year follow-up imaging were included. MRI assessments of the lumbar spine and sacroiliac joint evaluated inflammatory and structural lesions, including Romanus and Anderson lesions. Radiographic progression was defined as a ≥2-point increase in the modified Stoke Ankylosing Spondylitis Spinal Score. Statistical analyses compared clinical and imaging parameters between progression (n = 9) and nonprogression (n = 17) groups. RESULTS: Patients in the progression group had significantly higher baseline modified Stoke Ankylosing Spondylitis Spinal Score (P = .04) and modified-health assessment questionnaire scores (P = .04). Positive MRI findings of anterior and posterior corner inflammatory lesions and Anderson-central lesions were significantly associated with progression (P < .05). Romanus lesions, indicative of early structural changes, were more frequent in the progression group (P = .02). However, fat lesions and sacroiliac joint inflammation showed no significant predictive value. CONCLUSION: Baseline MRI findings, particularly inflammatory and Romanus lesions, are strong predictors of spinal ankylosis progression in axSpA. These results highlight the importance of incorporating MRI into personalized treatment strategies to mitigate disease progression. Further studies are needed to validate these findings in larger cohorts.

Synthetic octacalcium phosphate (OCP) has emerged as a potential precursor for bone apatite crystals, promoting faster bone formation and better biodegradability compared to hydroxyapatite and β-tricalcium phosphate materials. Combining OCP with various polymeric biomaterials enhances its ductility, making it suitable for clinical applications, including dentistry. Preclinical studies on OCP/gelatin (OCP/Gel) composites have shown excellent osteoconductive and osteoinductive properties, indicating potential for bone defect repairs. This study investigates the efficacy of OCP/Gel as a filler for lumbar interbody fusion cages. A miniature swine model underwent surgery using polyetheretherketone (PEEK) cages with different fillers: no filler, autologous rib, and OCP/Gel. Eight weeks post-surgery evaluations using computed tomography, histological assessments, and Fourier transform infrared (FT-IR) spectroscopy revealed that while PEEK cages without fillers showed no bone fusion, those with autologous rib and OCP/Gel demonstrated partial interbody fusion. Histological analysis indicated new bone growth in cages with OCP/Gel, and FT-IR spectroscopy confirmed the degradation of OCP at the vertebral interface and increased bone matrix proteins. The findings suggest that OCP/Gel could be a viable alternative to autologous bone grafts for lumbar interbody fusion surgeries, offering less invasive and more cost-effective solutions. The success of OCP/Gel in clinical applications could pave the way for broader use in orthopedic reconstructive surgeries, potentially eliminating the need for combined use of bone marrow aspirate or expensive growth factors.

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.

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.

<h4>Objectives</h4>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.<h4>Methods</h4>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.<h4>Results</h4>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).<h4>Conclusions</h4>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.

<h4>Objective</h4>Spondyloarthritis encompasses conditions such as ankylosing spondylitis (AS) and psoriatic arthritis (PsA). Advanced axial spondyloarthritis causes significant spinal fusion, affecting daily activities. Recent therapeutic agents have enhanced the control of inflammation, yet they do not consistently stop the axial progression. This study aimed to identify factors influencing the progression of axial lesions over a two-year period in Japanese patients with axial spondyloarthritis.<h4>Methods</h4>This retrospective and cross-sectional study included 47 axial spondyloarthritis patients. Spinal lesions were assessed using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Patients were categorized into progressive and non-progressive groups based on changes in their mSASSS scores. Various clinical parameters were analyzed for correlation with ankylosis progression.<h4>Results</h4>The study found no significant correlation between ankylosis progression and traditional factors, including the level of inflammation or the use of biologics. However, modified Health Assessment Questionnaire (mHAQ) scores were associated with disease progression. The baseline mSASSS was another significant factor, underscoring the importance of early detection and management.<h4>Conclusion</h4>This study showed that patient-reported outcomes and baseline mSASSS scores are crucial for assessing axial spondyloarthritis progression. This underscores the need for a comprehensive treatment strategy that addresses both clinical indicators and patient-reported outcomes.

<h4>Objective</h4>In this study, we employed a large language model to evaluate the diagnostic efficacy of radiology reports of bone scintigraphy in the context of identifying SAPHO syndrome, and further examined the potential of such a model to augment the diagnostic procedure.<h4>Methods</h4>Imaging data and clinical information of 151 patients (105/46 women/men, mean age: 53.5 years) who underwent bone scintigraphy for suspected Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO) syndrome between January 2007 and December 2022 were retrospectively reviewed. ChatGPT-4.0 was used as the large language model. The diagnostic performance of the large language model was verified by comparing the cases judged to have SAPHO syndrome that fulfilled Kahn's classification criteria based on a combination of concise radiology reports and skin lesions such as palmoplantar pustulosis, with cases diagnosed with SAPHO syndrome by rheumatologists based on all clinical information.<h4>Results</h4>The diagnostic accuracy of a large language model for analysing bone scintigraphy radiology reports in conjunction with information about skin symptoms, such as palmoplantar pustulosis, achieved a sensitivity of 83.5%, specificity of 69.4%, and an overall accuracy of 76.8%.<h4>Conclusion</h4>This research indicates the prospective value of extensive language models in scrutinizing radiology accounts from bone scintigraphy for the diagnosis of SAPHO syndrome.

<h4>Objective</h4>This study aimed to analyse the radiological characteristics and clinical diversity of Japanese patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome, a heterogeneous disorder.<h4>Methods</h4>Radiographs and clinical information from 115 Japanese patients (female/male: 81/34; mean age at onset: 48.7 years) diagnosed with SAPHO syndrome between January 2007 and December 2020 were retrospectively reviewed. Additionally, the treatment for SAPHO syndrome was explored.<h4>Results</h4>Among the 115 patients, 70 patients had complications, including palmoplantar pustulosis, acne, or psoriasis. Imaging studies included bone scintigraphy, magnetic resonance imaging, computed tomography, and positron emission tomography in 71, 58, 70, and 23 patients, respectively. The most frequent lesions were arthritis and hyperostosis of the sternoclavicular joints in 96 patients; spinal lesions, including sacroiliac arthritis, were observed in 85 patients. Peripheral aseptic osteitis was observed in 22 patients, and the tibia was involved in 12. The treatments consisted of analgesics, bisphosphonates, conventional synthetic disease-modifying antirheumatic drugs, and biologics (tumour necrosis factor inhibitors and interleukin-23p19 inhibitors) in 85, 15, 23, and 10 patients (8 and 2 patients), respectively.<h4>Conclusions</h4>Sternoclavicular hyperostosis and pustulosis are frequently observed in patients with SAPHO syndrome. Biological agents were more frequently used in patients with peripheral osteitis and arthritis.

<h4>Purpose</h4>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.<h4>Methods</h4>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.<h4>Results</h4>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.<h4>Conclusions</h4>Acetabular coverage has little effect on the necessity for surgical treatment and femoral head collapse in ONFH patients over a long-term follow-up.

Pyoderma gangrenosum (PG) is a rare inflammatory skin disease characterised by skin ulcers that are associated with autoimmune diseases. Although the effectiveness of immunosuppression with glucocorticoids and tumour necrosis factor inhibitors in treating PG has been reported, the utility of negative-pressure wound therapy (NPWT) for severe ulcerative lesions in patients with PG remains controversial. Herein, we report the case of a 76-year-old woman with rheumatoid arthritis who developed PG after undergoing surgery for a forefoot deformity. The patient showed improvement in deep ulcer lesions through NPWT while receiving treatment with abatacept and systemic glucocorticoids. Subsequent topical glucocorticoid therapy led to the remission of the PG. This case suggests that NPWT, when used under immunosuppressive conditions, does not exacerbate the pathergy and may be beneficial for treating severe ulcerative PG.

<h4>Background</h4>Clinical outcomes of Chiari pelvic osteotomy for acetabular dysplasia, including conversion to total hip arthroplasty (THA), have not been adequately explored. The purpose of this study was to examine the long-term results and clinical outcomes of Chiari pelvic osteotomy as the primary outcome and to analyze its prognostic factors as the second outcome.<h4>Methods</h4>This study was a multicenter, retrospective cohort study. Ninety-seven patients underwent Chiari pelvic osteotomy at three hospitals between March 1975 and October 1997. The long-term clinical outcomes of Chiari pelvic osteotomy, including conversion to THA and hip pain, were analyzed using the Kaplan-Meier method. In addition, the prognostic factors for conversion to THA after Chiari pelvic osteotomy were evaluated with clinical variables and radiographic parameters.<h4>Results</h4>The study included 51 hips in 45 patients (4 men and 41 women) with long-term follow-up. The survival rates assessed by Kaplan-Meier analysis with conversion to THA as an endpoint, were 90.2% (95% confidence interval (CI) 82.0-98.4%) at 20 years and 73.5% (95% CI 61.1-86.0%) at 30 years. In contrast, the Kaplan-Meier survival rates with the Japanese Orthopaedic Association hip score for pain ≤20 as an endpoint, were 86.3% (95% CI 76.8-95.7%) at 20 years and 65.6% (95% CI 52.3-79.0%) at 30 years. Only older age at osteotomy was the significantly poor prognostic factor for conversion to THA, with a hazard ratio of 1.11/year, 95% CI 1.06 to 1.18, (p < 0.01).<h4>Conclusion</h4>Chiari pelvic osteotomy may still be a good alternative to bony reconstructive surgery for acetabular dysplasia especially in young patients. Only older age at the osteotomy was related to the poor prognosis of preserving hip function.

<h4>Background</h4>Bone grafting is widely used to treat large bone defects. A porous composite of a bioactive octacalcium phosphate material with gelatin sponge (OCP/Gel) has been shown to biodegrade promptly and be replaced with new bone both in animal models of a membranous bone defect and a long bone defect. However, it is unclear whether OCP/Gel can regenerate bone in more severe bone defects, such as a critical-size transcortical defect.<h4>Questions/purposes</h4>Using an in vivo rat femur model of a standardized, transcortical, critical-size bone defect, we asked: Compared with a Gel control, does OCP/Gel result in more newly formed bone as determined by (1) micro-CT evaluation, (2) histologic and histomorphometric measures, and (3) osteocalcin staining and tartrate-resistant acid phosphatase staining?<h4>Methods</h4>Thirty-four 12-week-old male Sprague-Dawley rats (weight 356 ± 25.6 g) were used. Gel and OCP/Gel composites were prepared in our laboratory. Porous cylinders 3 mm in diameter and 4 mm in height were manufactured from both materials. The OCP/Gel and Gel cylinders were implanted into a 3-mm-diameter transcortical critical-size bone defect model in the left rat femur. The OCP/Gel and Gel were randomly assigned, and the cylinders were implanted. The biological responses of the defect regions were evaluated radiologically and histologically. At 4 and 8 weeks after implantation, CT evaluation, histological examination of decalcified samples, and immunostaining were quantitatively performed to evaluate new bone formation and remaining bone graft substitutes and activity of osteoblasts and osteoclast-like cells (n = 24). Qualitative histological evaluation was performed on undecalcified samples at 3 weeks postimplantation (n = 10). CT and decalcified tissue analysis was not performed blinded, but an analysis of undecalcified specimens was performed under blinded conditions.<h4>Results</h4>Radiologic analysis revealed that the OCP/Gel group showed radiopaque regions around the OCP granules and at the edge of the defect margin 4 weeks after implantation, suggesting that new bone formation occurred in two ways. In contrast, the rat femurs in the Gel group had a limited radiopaque zone at the edge of the defect region. The amount of new bone volume analyzed by micro-CT was higher in the OCP/Gel group than in the Gel group at 4 and 8 weeks after implantation (​​4 weeks after implantation: OCP/Gel versus Gel: 6.1 ± 1.6 mm 3 versus 3.4 ± 0.7 mm 3 , mean difference 2.7 [95% confidence interval (CI) 0.9 to 4.5]; p = 0.002; intraclass correlation coefficient [ICC] 0.72 [95% CI 0.29 to 0.91]; 8 weeks after implantation: OCP/Gel versus Gel: 3.9 ± 0.7 mm 3 versus 1.4 ± 1.1 mm 3 , mean difference 2.5 [95% CI 0.8 to 4.3]; p = 0.004; ICC 0.81 [95% CI 0.47 to 0.94]). Histologic evaluation also showed there was a higher percentage of new bone formation in the OCP/Gel group at 4 and 8 weeks after implantation (​​4 weeks after implantation: OCP/Gel versus Gel: 31.2% ± 5.3% versus 13.6% ± 4.0%, mean difference 17.6% [95% CI 14.2% to 29.2%]; p < 0.001; ICC 0.83 [95% CI 0.53 to 0.95]; 8 weeks after implantation: OCP/Gel versus Gel: 28.3% ± 6.2% versus 9.5% ± 1.9%, mean difference 18.8% [95% CI 11.3% to 26.3%]; p < 0.001; ICC 0.90 [95% CI 0.69 to 0.97]). Bridging of the defect area started earlier in the OCP/Gel group than in the Gel group at 4 weeks after implantation. Osteocalcin immunostaining showed that the number of mature osteoblasts was higher in the OCP/Gel group than in the Gel group at 4 weeks (OCP/Gel versus Gel: 42.1 ± 6.5/mm 2 versus 17.4 ± 5.4/mm 2 , mean difference 24.7 [95% CI 16.2 to 33.2]; p < 0.001; ICC 0.99 [95% CI 0.97 to 0.99]). At 4 weeks, the number of osteoclast-like cells was higher in the OCP/Gel composite group than in the Gel group (OCP/Gel versus Gel: 3.2 ± 0.6/mm 2 versus 0.9 ± 0.4/mm 2 , mean difference 2.3 [95% CI 1.3 to 3.5]; p < 0.001; ICC 0.79 [95% CI 0.35 to 0.94]).<h4>Conclusion</h4>OCP/Gel composites induced early bone remodeling and cortical bone repair in less time than did the Gel control in a rat critical-size, transcortical femoral defect, suggesting that OCP/Gel could be used as a bone replacement material to treat severe bone defects.<h4>Clinical relevance</h4>In a transcortical bone defect model of critical size in the rat femur, the OCP/Gel composite demonstrated successful bone regeneration. Several future studies are needed to evaluate the clinical application of this interesting bone graft substitute, including bone formation capacity in refractory fracture and spinal fusion models and the comparison of bone strength after repair with OCP/Gel composite to that of autologous bone.