Minimal Influence on Muscle Strength and Patient Reported Outcome Measures by Conjoined Tendon Detachment in Anterolateral Muscle-Sparing Total Hip Arthroplasty.

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.

Low Young's Modulus TiNbSn Alloy Locking Plates Accelerate Osteosynthesis in Rabbit Tibiae.

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.

TiNbSn stems with gradient changes of Young's modulus and stiffness reduce stress shielding compared to the standard fit-and-fill stems.

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.

Long-term results of Chiari pelvic osteotomy on the preservation of hip function with mean follow-up of more than 30 years and its prognostic factors.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Antimicrobial Properties of TiNbSn Alloys Anodized in a Sulfuric Acid Electrolyte.

TiNbSn alloy is a high-performance titanium alloy which is biosafe, strong, and has a low Young's modulus. TiNbSn alloy has been clinically applied as a material for orthopedic prosthesis. Anodized TiNbSn alloys with acetic and sulfuric acid electrolytes have excellent biocompatibility for osseointegration. Herein, TiNbSn alloy was anodized in a sulfuric acid electrolyte to determine the antimicrobial activity. The photocatalytic activities of the anodic oxide alloys were investigated based on their electronic band structure and crystallinity. In addition, the cytotoxicity of the anodized TiNbSn alloy was evaluated using cell lines of the osteoblast and fibroblast lineages. The antimicrobial activity of the anodic oxide alloy was assessed according to the ISO 27447 using methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Escherichia coli. The anodic oxide comprised rutile and anatase titanium dioxide (TiO2) and exhibited a porous microstructure. A well-crystallized rutile TiO2 phase was observed in the anodized TiNbSn alloy. The methylene blue degradation tests under ultraviolet illumination exhibited photocatalytic activity. In antimicrobial tests, the anodized TiNbSn alloy exhibited robust antimicrobial activities under ultraviolet illumination for all bacterial species, regardless of drug resistance. Therefore, the anodized TiNbSn alloy can be used as a functional biomaterial with low Young's modulus and excellent antimicrobial activity.

Five cases of seronegative persistent inflammatory monoarthritis improved with biological therapy.

Persistent inflammatory monoarthritis is defined as inflammation of one joint that continues for longer than 3 months. Most cases remain as nonspecific arthritis after several years. Persistent inflammatory monoarthritis is difficult to diagnose and treat in the early stage because there are no criteria for diagnosis and treatment. We report five seronegative persistent inflammatory monoarthritis cases that affected the left knee, right knee, left knee, left ankle, and right knee. All patients underwent joint punctures; two patients received steroid injections in the affected joint. The bacterial and mycobacterial culture were negative in all patients. Two patients received oral steroids, and two patients were administered nonsteroidal anti-inflammatory drugs; however, their symptoms did not improve, and one patient experienced progression of joint destruction. We investigated the usefulness of biological disease-modifying antirheumatic drugs for the treatment of seronegative persistent inflammatory monoarthritis. We obtained a remarkable improvement effect and prevented the advance of joint destruction.

ß-type TiNbSn Alloy Plates With Low Young Modulus Accelerates Osteosynthesis in Rabbit Tibiae.

BACKGROUND: Ti6Al4V alloy, which is commonly used for biomedical applications, has a Young modulus (110 GPa) that is higher than that of human cortical bone (11 to 20 GPa). Using an implant with a material with a low Young modulus that enhances load sharing by the bone even more than those made of Ti6Al4V could be beneficial for bone healing and further reduce the potential for stress shielding. A new ß-type TiNbSn alloy has a low Young modulus of approximately 40 to 49 GPa. However, whether the new titanium alloy with a lower Young modulus is advantageous in terms of fracture healing has not been assessed, and a small-animal model seems a reasonable first step in its assessment. QUESTIONS/PURPOSES: To assess the impact of a TiNbSn alloy plate with a lower Young modulus compared with a Ti6Al4V alloy plate on fracture healing, we evaluated: (1) bony bridging and callus volume, (2) new bone formation and remaining cartilage tissue, (3) osteoblast activity in the callus, and (4) mechanical strength and stiffness of the callus in bending. METHODS: Fracture plates manufactured from TiNbSn and Ti6Al4V alloys, which have Young moduli of 49 GPa and 110 GPa, respectively, were compared. The main reason for using rabbits was the high reliability of the three-point bending mechanical test of the rabbit tibia. Forty-two male Japanese white rabbits weighing 2.8 to 3.4 kg were anesthetized. A 5-cm skin incision was made on the medial side in the mid-diaphysis of the right tibia. Eight-hole plates were used, which were 42 mm long, 5 mm wide, and 1.2 mm thick. Plate fixation was performed using three proximal and three distal screws. After the plate was installed, an osteotomy was performed using a 1-mm-wide wire saw to create a standardized tibial transverse osteotomy model with a 1-mm gap. Bone healing was quantitatively assessed by two nonblinded observers using micro-CT (bony bridging and callus volume), histomorphometry (new bone formation and remaining cartilage tissue), immunohistochemistry (osteoblast activity), and mechanical testing (mechanical strength and stiffness in bending). Measurements on nondemineralized specimens were descriptive statistics due to their small number. Four weeks after osteotomy and fixation, 30 rabbits were euthanized to undergo micro-CT and subsequent mechanical testing (n = 12), histomorphometry and immunohistochemistry with demineralized specimens (n = 12), and histomorphometry with a nondemineralized specimen (n = 6). Eight weeks postoperatively, 12 rabbits were euthanized for micro-CT and subsequent mechanical testing. RESULTS: Intramedullary fracture calluses treated with TiNbSn alloy plates had larger bone volumes and more numerous bridging structures than those treated with Ti6Al4V alloy plates at 4 weeks after osteotomy (Ti6Al4V alloy versus TiNbSn alloy: 30 ± 7 mm 3 versus 52 ± 14 mm 3 , mean difference 22 [95% CI 9 to 37]; p = 0.005; ICC 0.98 [95% CI 0.95 to 0.99]). Histologic assessments demonstrated there was greater new bone formation (total callus: Ti6Al4V versus TiNbSn: 16 ± 4 mm 2 versus 24 ± 7 mm 2 , mean difference 8 [95% CI 1 to 16]; p = 0.04; ICC 0.98 [95% CI 0.93 to 0.99]; intramedullary callus: Ti6Al4V versus TiNbSn: 6 ± 4 mm 2 versus 13 ± 5 mm 2 , mean difference 7 [95% CI 1 to 13]; p = 0.02; ICC 0.98 [95% CI 0.95 to 0.99]) and a higher number of osteocalcin-positive cells (Ti6Al4V alloy versus TiNbSn alloy: 1397 ± 197 cells/mm 2 versus 2044 ± 183 cells/mm 2 , mean difference 647 [95% CI 402 to 892]; p < 0.001; ICC 0.98 [95% CI 0.95 to 0.99]) in the TiNbSn alloy group than in the Ti6Al4V alloy group. At 4 weeks after osteotomy, both bone strength and stiffness of the healed bone in the TiNbSn alloy group were higher than those in the Ti6Al4V alloy group (maximum load: Ti6Al4V alloy versus TiNbSn alloy: 83 ± 30 N versus 127 ± 26 N; mean difference 44 [95% CI 8 to 80]; p = 0.02; stiffness: Ti6Al4V alloy versus TiNbSn alloy: 92 ± 43 N/mm versus 165 ± 63 N/mm; mean difference 73 [95% CI 4 to 143]; p = 0.047). Eight weeks after osteotomy, no between-group differences were observed in the strength and stiffness of the healed bone. CONCLUSION: The results of this study indicate that TiNbSn alloy plate with a lower Young modulus resulted in improved bone formation and stiffer callus during the early phase (4 weeks after surgery) but not the later phase (8 weeks after surgery) of bone healing. CLINICAL RELEVANCE: An overly stiff plate may impair callus formation and bone healing. The TiNbSn alloy plate with a low Young modulus improves the early formation of new bone and stiff callus at the osteotomy site compared with the Ti6Al4V alloy plate in the healing process, which may promote bone repair. TiNbSn alloy may be a promising biomaterial for fracture treatment devices. Further research to address concerns about the strength of TiNbSn alloy plates, such as fatigue life and plate fracture, will be necessary for clinical applications, including mechanical tests to verify fatigue life and validation in larger animals with greater body weight.

Antibacterial Activity of an Anodized TiNbSn Alloy Prepared in Sodium Tartrate Electrolyte.

In this study, we anodized a TiNbSn alloy with low Young's modulus in an electrolyte of sodium tartrate with and without hydrogen peroxide (H2O2). The photo-induced characteristics of the anodized alloy were analyzed for crystallinity and electrochemical conditions with comparisons to the effect with the addition of H2O2. The antibacterial activity was evaluated using methicillin-resistant Staphylococcus aureus and other pathogenic bacteria according to ISO 27447, and time decay antibacterial tests were also conducted. The anodized oxide had a porous microstructure with anatase- and rutile-structured titanium dioxide (TiO2). In contrast, the peaks of rutile-structured TiO2 were accelerated in the anodized TiNbSn alloy with H2O2. The formation of hydroxyl radicals and methylene blue breaching performance under ultraviolet irradiation was confirmed in the anodic oxide on TiNbSn alloy with and without H2O2. The anodic oxide on TiNbSn alloy had a robust antibacterial activity, and no significant difference was detected with or without H2O2. We conclude that anodized TiNbSn alloy with sodium tartrate electrolyte may be a functional biomaterial with a low Young's modulus and an antibacterial function.

Association between Hip Center Position and Isokinetic Hip Muscle Performance after Anterolateral Muscle-Sparing Total Hip Arthroplasty.

Background and objectives: The superior placement of the acetabular cup induced the delayed recovery of abductor muscle moment after total hip arthroplasty (THA) with a conventional posterior approach. The anterior-based muscle-sparing (ABMS) THA effectively reduces soft tissue damage, including muscles. The influence of hip center position on anterior-based muscle-sparing (ABMS) total hip arthroplasty (THA) for post-operative hip muscle strength was unclear. We evaluate whether the hip center position affects the recovery of hip muscle strength after ABMS THA. Materials and Methods: The study was performed as a retrospective cohort study, and included 38 hips in 38 patients that underwent primary ABMS THA. Muscle strength was measured using isokinetic dynamometry before the operation, and at 6 and 12 months after surgery. The horizontal and vertical centers of rotation (H-COR and V-COR), vertical shift (V-shift), leg length, and global femoral offset were determined radiographically in reference to a previous report. Results: A weak negative correlation was observed between abduction muscle strength at 6 months and V-shift; a V-shift more than 15 mm demonstrated significantly decreased abductor muscle strength at 6 months. Conclusions: The superior placement of the hip center caused delayed recovery of abductor muscle strength in hips with anterolateral minimally invasive THA. There seems to exist no biomechanical reason why the same should not also be the case for the muscle-sparing approach.

Impacts of external rotators and the ischiofemoral ligament on preventing excessive internal hip rotation: a cadaveric study.

BACKGROUND: This study examined the biomechanics of preventing excessive internal hip joint rotation related to the hip flexion angle. METHOD: An intramedullary nail with a circular plate equipped with a protractor was installed in the femur of nine normal hips. The circular plate was pulled by 3.15 Nm of force in the internal rotation direction. The external rotators were individually resected, finally cutting the ischiofemoral ligament. The cutting order of the external rotators differed on each side to individually determine the internal rotation resistance. The external rotators were resected from the piriformis to the obturator externus in the right hips and the reverse order in the left hips. Traction was performed after excising each muscle and ischiofemoral ligament. Measurements were taken at 0°, 30°, and 60° of hip flexion, and the differences from baseline were calculated. RESULTS: For the right hip measurements, the piriformis and ischiofemoral ligament resection significantly differed at 0° of flexion (p = 0.02), each external rotator and the ischiofemoral ligament resections significantly differed at 30° of flexion (p < 0.01), and the ischiofemoral ligament and piriformis and inferior gemellus resections significantly differed at 60° of flexion (p = 0.04 and p = 0.02, respectively). In the left hips, the ischiofemoral ligament and obturator externus, inferior gemellus, and obturator internus resections significantly differed at 0° of flexion (p < 0.01, p < 0.01, and p = 0.01, respectively), as did each external rotator and the ischiofemoral ligament resections at 30° of flexion (p < 0.01). CONCLUSION: The ischiofemoral ligament primarily restricted the internal rotation of the hip joint. The piriformis and obturator internus may restrict internal rotation at 0° and 60° of flexion.

The intraoperative hip range of motion in total hip arthroplasty predicts postoperative patient's satisfaction for cutting toenails and putting on sock.

BACKGROUND: Restricted hip range of motion (ROM) has been proposed as a useful diagnostic tool for osteoarthritis. The relations between the intraoperative hip ROM under anesthesia in total hip arthroplasty (THA) and recovery of clinical mobility outcomes were unclear. This study evaluated the association between the intraoperative hip ROM under anesthesia in THA and the postoperative recovery of clinical mobility, including cutting toenails and putting on socks after THA. METHODS: The study was performed as a prospective cohort study and included 93 hips in 85 patients who underwent primary anterior-based muscle-sparing THA in the supine position. The hip ROM was evaluated under anesthesia before skin incision and intraoperative stability test. The Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ) was evaluated. A questionnaire on whether and how patients could cut toenails and putting on socks was assessed. The relationship between hip ROM at intraoperative stability tests and JHEQ moving score, cutting toenails, and putting on socks scores were evaluated statistically. RESULTS: We observed a week positive correlation between intraoperative hip ROM and the total of JHEQ mobility score. A moderate positive correlation was observed between external rotation angle with flexion 90°and cutting toenails and putting on socks score oh JHEQ. 94.6% and 96.8% of the patients could cut their toenails and putting on socks by themselves after surgery. The optimum cutoff range for high patient satisfaction for putting on socks and cutting toenails was 110° for flexion and 35°-40° for the external rotation angle in the intraoperative stability test. CONCLUSION: Hip ROM during intraoperative stability testing, especially the external rotation angle can predict postoperative outcomes and patient satisfaction for cutting toenails and putting on socks. We suggested that the capsule or capsular ligament release around the hip was increased to provide sufficient ROM without compromising stability.

Limited effects on patient outcomes of conjoint tendon release in anterolateral muscle-sparing total hip arthroplasty.

BACKGROUND: The anterolateral muscle-sparing total hip arthroplasty (THA) in the supine position is advantageous owing to the very low-dislocation rate and excellent leg length discrepancy control. However, femur exposure is challenging. Although the conjoined external rotators tendon (CERT) release is effective in improving femoral access, the effects on clinical outcomes remain unclear. The purpose of this study was to evaluate the clinical and radiographic results of CERT release in the anterolateral muscle-sparing THA approach. METHODS: The study was performed as a retrospective cohort study and included 85 hips in 85 patients who underwent primary anterolateral THA. Clinical and radiographic outcomes were investigated 6 months and 1 year after THA (CERT-preserved and non-released patients). The Japanese Orthopaedic Association (JOA) hip score, JOA Hip-disease Evaluation Questionnaire (JHEQ), forgotten joint score (FJS), and the 36 short-form questionnaires (SF-36 mental and physical) were evaluated. The leg length discrepancy, cup inclination and stem orientation were evaluated with radiographs. RESULTS: Among all the included hips, 37 patients (43.5%) retained the CERT, and 48 patients (56.5%) included the released CERT. There were no significant differences in the JOA hip scores, JHEQ, FJF-12 and SF-36 between the released and non-released groups. There were significant differences in sagittal stem alignments between groups. CONCLUSION: The CERT release in anterolateral muscle-sparing THA has a limited effect on post-operative clinical outcomes. The CERT release improved the femur exposure and is more invasive than the preserved CERT. We infer that the CERT should be maintained in patients with a wide range of motions, and release the CERT in inadequate femur canal preparation cases.

Effect of interleukin-17A inhibitor in Japanese patients with psoriatic arthritis compared with tumor necrosis factor-alpha inhibitor.

OBJECTIVES: The patient of severe psoriatic arthritis (PsA) is mainly treated with oral methotrexate, ciclosporin, and anti-tumor necrosis factor-alpha inhibitors (TNFi). Recently, anti-interleukin-17A inhibitors (IL-17Ai) have been used in the treatment of PsA. This study aimed to evaluate the efficacy and safety of IL-17Ai in Japanese patients with PsA compared with those of TNFi. METHODS: This was a longitudinal and retrospective study. The study population included 31 Japanese patients with PsA. All enrolled patients fulfilled the Classification Criteria for Psoriatic Arthritis. All patients were treated with TNFi or IL-17Ai. The assessed clinical manifestations were C-reactive protein (CRP)-based Disease Activity Score in 28 Joints (DAS28-CRP), disease activity in psoriatic arthritis (DAPSA), 20% achievement of American College of Rheumatology core set, swollen joint count (SJC), tender joint count (TJC), and visual analog scale (VAS). Functional ability of patients with PsA was analyzed using the modified health assessment questionnaire (mHAQ) score. We evaluated the parameters at baseline and weeks 12, 24, and 52. RESULTS: The change in SJC, TJC, VAS, mHAQ, and DAPSA had no significant difference at weeks 12, 24, and 52. The improvements of CRP and DAS28-CRP were significantly higher in TNFi group only at week 12. The biologics retention rate was significantly higher in TNFi group by the log-rank test. No critical adverse events occurred. CONCLUSIONS: Our study presented that IL-17Ai had treatment effects comparable to TNFi. IL-17Ai might have the potential to become an alternative to the previous drug, but more large-scale studies are expected.

Effect of denosumab switched from bisphosphonates in preventing joint destruction in postmenopausal rheumatoid arthritis patients with anti-cyclic citrullinated peptide antibodies.

INTRODUCTION: This study aimed to determine the effects of denosumab treatment on the joint destruction of Japanese females with rheumatoid arthritis (RA) and anti-cyclic citrullinated peptide (CCP) antibodies. MATERIALS AND METHODS: This retrospective longitudinal study included 56 patients treated with denosumab and 50 patients treated with bisphosphonate. All participants were positive for anti-CCP antibodies. All patients also had a history of osteoporosis treatment with bisphosphonate, which was either continued or switched to 60 mg of subcutaneous denosumab injection every 6 months. To assess the progression of joint destruction, hand and foot radiographs were taken, and changes in modified total Sharp score (mTSS), erosion score (ERO), and joint space narrowing score (JSN) were evaluated at 12 months and 24 months. The changes in BMD of the lumbar spine and hip were also assessed at 12 months. RESULTS: At 12 months, there were significant differences in the change of ERO (p = 0.015) and mTSS (p = 0.01). Similarly, there were significant differences in the change of ERO (p = 0.013) and mTSS (p = 0.003) at 24 months. In contrast, no significant difference was observed in the changes of JSN and clinical parameters. There were significant differences in the changes in BMD in the femoral neck (p = 0.011) and total hip (p = 0.012). CONCLUSION: Denosumab treatment might be effective for the inhibition of bone erosion progression in the patients with RA, and it potentially contributes to the treatment of osteoporosis and prevention of destructive arthritis in patients with switching treatment from bisphosphonate.

Biomechanical analysis of supra-acetabular insufficiency fracture using finite element analysis.

BACKGROUND: Supra-acetabular insufficiency fractures (SAIFs) occur in the upper acetabulum and are rare compared with insufficiency sacral, femoral head, or ischial fractures. However, SAIFs are known to occur in low grade trauma, and the underlying mechanism is still remained unclear. METHODS: We performed biomechanical analysis using finite element analysis to clarify the mechanisms underlying the development of SAIFs. Patient-specific models and bone mineral density (BMD) were derived from pelvic computed tomography data from two patients with SAIF (unaffected side) and two healthy young adults. The bone was assumed to be an isotropic, linearly elastic body. We assigned Young's modulus of each element to the pelvis based on the BMD, and reported the relationships for BMD-modulus. Clinically relevant loading conditions-walking and climbing stairs-were applied to the models. We compared the region of failure risk in each acetabulum using a maximum principal strain criterion. RESULTS: The average supra-acetabular BMD was less than that of the hemi-pelvis and femoral head, but was higher than that of the femoral neck and greater trochanter. Greater minimum principal strain was concentrated in the supra-acetabular portion in both the SAIF and healthy models. In the SAIF models, the higher region of the failure risk matched the fracture site on the acetabulum. CONCLUSIONS: Relative fragility causes compressive strain to concentrate in the upper acetabulum when walking and climbing stairs. When presented with a patient complaining of hip pain without apparent trauma or abnormal X-ray findings, physicians should consider the possibility of SAIF and perform magnetic resonance imaging for the diagnosis of SAIF.