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Background: Femoral neck stress fractures are rare and often recognized as overuse injuries that occur in young athletes or military personnel. A case following osteonecrosis of the femoral head is quite rare; even more uncommon is its occurrence in the bilateral hips. Magnetic resonance imaging has been established as the preferred tool for diagnosing nondisplaced femoral neck stress fracture due to overuse injury. Magnetic resonance imaging was also useful to detect the initial lesion even in this case, although the etiology was different between overuse injury and insufficiency fracture., Case Presentation: A 41-year-old Japanese woman diagnosed with bilateral early stage idiopathic osteonecrosis of the femoral head was observed non-weight-bearing as much as possible using a stick. However, her pain and difficulty in walking progressed. Bilateral femoral neck stress fractures were subsequently detected by magnetic resonance imaging. The fracture initially appeared as a spot of bone marrow edema at the medial site of the femoral neck, and then developed into a fracture line. The patient underwent internal fixation of both hips with sliding hip screws to stabilize the stress fractures. In addition, the preparatory reaming served as core decompression of the femoral heads, as well as being treatment for osteonecrosis. Her bone mineral density and 25-hydroxy vitamin D values were low for her age. We administered eldecalcitol and teriparatide acetate. Her symptoms mostly improved, and the fracture lines and necrotic lesions on magnetic resonance imaging reduced at 5 months after the surgery., Conclusions: Bilateral femoral neck stress fractures are a very rare condition and are often missed. It is important to listen to the patient's complaints and perform an appropriate examination. We encountered a case of bilateral femoral neck stress fracture that occurred in a patient with early stage osteonecrosis of the femoral head, and were able to observe progression of stress fracture since before fracture occurred. This is considered to be the first report to capture imaging changes before and after the onset., (© 2021. The Author(s).)

Background: Flexor digitorum superficialis (FDS) muscle provides dynamic stabilization and medial elbow support for ulnar collateral ligament (UCL). The FDS contraction significantly affects the medial joint distance (MJD) through grip contraction. However, it remains unclear whether FDS activity alone contributes to medial elbow stability, or together with the activation of the flexor digitorum profundus during grip contraction, and which finger's FDS is the main contributor to elbow stability. We investigated the resistive effects of isolated FDS contraction in individual fingers against valgus stress in the elbow joint using stress ultrasonography (US)., Methods: We investigated 17 healthy males (mean age, 27 ± 5 years). Valgus stress US was performed using the Telos device, with the elbow at 30° flexion. MJD was measured for each arm during 3 separate conditions: at rest (unloaded), under valgus load (50 N) (loaded), and under valgus load with FDS contracted in individual fingers (loaded-contracted)., Results: MJD was significantly longer when loaded (5.4 ± 0.4 mm) than unloaded (4.1 ± 0.2 mm, P = 0.007) or loaded-contracted (4.6 ± 0.3 mm, P = 0.003) for each finger. When loaded-contracted, MJD differed statistically between the index and ring fingers (P = 0.03) and between the middle and ring fingers (P = 0.04). However, the difference between the index and middle fingers was not statistically significant (P = 0.08)., Conclusions: Individual FDS contraction, particularly of the index and middle fingers, contributes most to stabilization against valgus stress. Thus, injury care programs should incorporate FDS exercises of these fingers.

Background: Idiopathic osteonecrosis of the femoral head (ONFH) occurs at a relatively younger age. It is therefore important to prevent the resultant femoral head collapse and requirement of total hip arthroplasty in these patients. In 2003, we initiated concentrated autologous bone marrow aspirate transplantation (CABMAT), a joint-preserving treatment for ONFH, at our institution. Here, we report the long-term results of CABMAT treatment., Methods: We retrospectively collated and analyzed the demographic and treatment data of 69 patients (109 hips) with idiopathic ONFH treated with CABMAT between April 2003 and April 2008., Results: Totally, 44 patients (21 men, 23 women, 80 hips) completed the 10-year follow-up. The follow-up rate was 73.4%, and the mean follow-up period was 12.0 (range, 10.0-15.4) years. The mean age of the patients was 42.2 (range, 16.3-70.5) years. Using the Association Research Circulation Osseous (ARCO) classification system for preoperative analysis, 12, 31, 32, and 5 hips were classified as stages 1, 2, 3, and 4, respectively. The overall rate of conversion to total hip arthroplasty (THA) was 34% (27/80 hips). In a multivariate regression analysis, the preoperative stage of ONFH and the body mass index were found to correlate significantly with conversion to THA. Totally, 43 hips (of 80) were classified as belonging to the pre-collapse stage (i.e., stages 1 or 2). The overall collapse rate and the THA-conversion rate of these hips were estimated to be 49% (21/43) and 14% (6/43), respectively., Conclusions: On the basis of our long-term findings, the minimally invasive and feasible CABMAT therapy can be utilized as one of a joint-preserving treatment for ONFH.

Introduction: Xanthoma disseminatum is a very rare disease classified as a benign non-Langerhans cell histiocytosis, which is rarely associated with osteoarticular lesions. There is only a report of tumor abrasion during treatment of osteoarticular lesions of this disease, artificial joint replacement has not been reported. We describe a patient in whom bilateral total joint replacement was performed for disseminated xanthoma lesions of the hip joints., Case Presentation: A 34-year-old Japanese woman had a chief complaint of bilateral coxalgia. She had been diagnosed as having disseminated xanthoma. Radiographs showed numerous 5-mm radiolucent bands that resembled worm-eaten tracks in the lower part of the femoral heads adjacent to the joint surface. In addition, short tau inversion recovery imaging scans showed high-intensity areas from the femoral head to the neck in both femurs, suggesting bone marrow edema. Total hip arthroplasty was performed for hip arthrosis on both hip joints caused by disseminated xanthoma. Deflection of the implants was a concern from the early stages postoperatively, but both the imaging and clinical findings have been satisfactory for 4 years of follow-up., Conclusions: A very unusual hip joint lesion of xanthoma disseminatum was replaced with a total artificial joint replacement, and the course over 4 years was good. Our patient's course will continue to be followed carefully.

Objective: We previously established concentrated autologous bone marrow aspirate transplantation as a one-step, lowly invasive, joint-preserving surgical technique for treating osteonecrosis of the femoral head. The objectives of this study were to identify factors that may predict the mesenchymal stem cell (MSC) count in bone marrow aspirate, concentrated using our method, and to clarify etiology related differences in the number of MSCs in concentrated bone marrow aspirate., Results: The MSC counts per 10 6 nucleated cells before concentration in the steroid, alcohol, and trauma groups were 2.31 ± 2.96, 2.58 ± 2.30, and 1.95 ± 1.85, respectively. The MSC counts per 10 6 nucleated cells after concentration were 3.23 ± 3.41, 3.30 ± 2.83, and 2.56 ± 1.98 cells, respectively. The MSC concentration rates in the steroid, alcohol, and trauma groups were 7.15 ± 5.62, 5.08 ± 1.96, and 8.23 ± 4.82 times, respectively. None of the differences were significant. Multiple regression analysis revealed that MSC count was related to the total bone marrow aspirated, peripheral blood platelet count, and nucleated cell count in the initial aspiration.

Background: Maintenance or restoration of a good range of motion of the knee is one of the most important outcomes following knee surgery. According to previous studies, opening wedge high tibial osteotomy enables better recovery of range of motion in knee flexion than that achievable after total knee arthroplasty or unicompartmental knee arthroplasty. However, few reports provide a detailed description of the postoperative recovery of knee extension range of motion after opening wedge high tibial osteotomy. We describe our experience with a knee extension training program using a single-joint hybrid assistive limb device (HAL-SJ; Cyberdyne Inc., Tsukuba, Japan) during the acute recovery phase after opening wedge high tibial osteotomy. The HAL-SJ is a wearable robotic device that facilitates voluntary control of knee joint motion., Case Presentation: A 67-year-old Japanese woman who underwent opening wedge high tibial osteotomy for spontaneous osteonecrosis of the left medial femoral condyle received HAL-SJ-based knee extension training postoperatively. Our experience with this patient revealed that knee extension training with the HAL-SJ during the acute phase following opening wedge high tibial osteotomy is feasible. Furthermore, the patient's knee extension range of motion improved to values similar to those seen during the preoperative stage, and her flexion range of motion was improved at 3 months after the surgery., Conclusions: HAL-SJ-based knee extension training could be used as a novel post-opening wedge high tibial osteotomy rehabilitation modality. Further exploration of individualized optimal settings of the HAL-SJ is required to improve its safety and efficacy.

Background: We had previously established concentrated autologous bone marrow aspirate transplantation (CABMAT), a one-step, low-invasive, joint-preserving surgical technique for treating osteonecrosis of the femoral head (ONFH). The present study aimed to evaluate the effects of CABMAT as a hip preserving surgical approach, preventing femoral head collapse in asymptomatic ONFH., Methods: In total, 222 patients (341 hips) with ONFH were treated with CABMAT between April 2003 and March 2013. Based on magnetic resonance imaging, we determined that 119 of these patients had bilateral asymptomatic ONFH (238 hips), and 38 further patients had unilateral asymptomatic ONFH (38 hips). In this series, we retrospectively examined 31 hips in 31 patients with unilateral asymptomatic ONFH treated surgically between 2003 and 2012 and followed up for more than 2 years. Clinical and radiological evaluation were performed immediately before the procedure and at the final follow-up. The two-year follow-up rate among patients with unilateral ONFH was 82% (31/38). Therefore, the present study included 31 patients (19 males and 12 females), with a mean age and follow-up period of 40 and 5.8 years, respectively. Of the 31 asymptomatic hips, 5, 6, 10, and 10 had osteonecrosis of types A, B, C1, and C2, respectively. The diagnosis, classification, and staging of ONFH were based on the 2001 Japanese Orthopaedic Association (JOA) classification., Results: Secondary collapse of the femoral head was observed in 6/10 hips and 5/10 hips with osteonecrosis of types C1 and C2, respectively. Total hip arthroplasty was performed in 9.6% of patients (3/31 hips), at an average of 33 months after surgery. Clinical symptoms improved after surgery, and the secondary collapse rate at a mean of 5.8 years after CABMAT was lower than that reported in several previous studies on the natural course of asymptomatic ONFH., Conclusions: Early diagnosis of ONFH (i.e., before femoral head collapse) and early intervention with CABMAT could improve the clinical outcome of corticosteroid and alcohol-induced ONFH.

Background: There has been no report to date regarding retraction patterns of delaminated rotator cuff tears. The purpose of this study was to evaluate the incidence and tearing patterns of delamination and repair integrity after the dual-layer repair of delaminated cuff tears., Methods/design: A consecutive series of 64 patients with posterosuperior rotator cuff tears underwent arthroscopic rotator cuff repair from August 2011 to September 2012. Among the patients, 53 who received either dual-layer double-row (DLDR) repair or dual-layer suture bridge (DLSB) repair and 11 who received a single-layer repair were evaluated. The mean follow-up period after surgery was 26.5 months. The retraction direction of the deep and superficial layers was analyzed, and the integrity of the repaired constructs was determined in 37 patients through magnetic resonance imaging at a mean of 12.1 months after surgery., Results: The incidence of delamination was 82.8 %. Posteromedial retraction of the deep and superficial layers was observed in 98.1 and 88.5 % of cases, respectively. The Constant score and UCLA score increased preoperatively to postoperatively, showing no significant differences between the dual-layer repair group and single-layer repair group. Retear was found in two (7.6 %) patients in the dual-layer repair group and three (27.2 %) patients in the single-layer repair group (p = 0.016)., Conclusions: Differential rotator cuff repair strategies are needed to address rotator cuff tears, since recent studies have changed our concept of rotator cuff tears. We have focused on three areas: incidence, retraction patterns, and clinical outcomes. The incidence of delamination was extremely high. Both the superficial layer and deep layer were mainly retracted posteromedially. The retraction of the deep layer and superficial layer may be affected by the infraspinatus. Dual-layer rotator cuff repair based on the retraction pattern of delamination is recommended for improvement of repair integrity and of clinical outcomes.