The impact of chronic obstructive pulmonary disease on bone strength.

Chronic obstructive pulmonary disease (COPD) is a lifestyle-related disease that develops in middle-aged and older adults, often due to smoking habits, and has been noted to cause bone fragility. COPD is a risk factor for osteoporosis and fragility fracture, and a high prevalence of osteoporosis and incidence of vertebral fractures have been shown in patients with COPD. Findings of lung tissue analysis in patients with COPD are primarily emphysema with a loss of alveolar septal walls, and the severity of pulmonary emphysema is negatively correlated with thoracic spine bone mineral density (BMD). On the other hand, epidemiological studies on COPD and fracture risk have reported a BMD-independent increase in fracture risk; however, verification in animal models and human bone biopsy samples has been slow, and the essential pathogenesis has not been elucidated. The detailed pathological/molecular mechanisms of musculoskeletal complications in patients with COPD are unknown, and basic research is needed to elucidate the mechanisms. This paper discusses the impacts of COPD on bone strength, focusing on findings in animal models in terms of bone microstructure, bone metabolic dynamics, and material properties.

Endoscopic Shelf Acetabuloplasty Combined With Hip Arthroscopic Labral Repair, Cam Osteoplasty, and Capsular Plication Enables Elite Athletes With Acetabular Dysplasia to Return to Sport: A Case Series.

OBJECTIVE: To investigate clinical outcomes and return to sport timeline for athletes with acetabular dysplasia after endoscopic shelf acetabuloplasty (ESA). DESIGN: A retrospective review. SETTING: Wakamatsu Hospital of the University of Occupational and Environmental Health, Japan between 2012 and 2019. PATIENTS: Fifteen elite athletes (median age: 20 years) of 253 patients undergoing ESA, arthroscopic labral repair/reconstruction, cam osteochondroplasty, and capsular plication. The mean follow-up period was 27.8 months after surgery. MAIN OUTCOME MEASURES: Patient-reported outcome scales (PROSs), including the modified Harris Hip Score, Nonarthritic Hip Score, International Hip Outcome Tool 12, Hip Outcome Score-Sports, and Vail Hip Score. RESULTS: After ESA, all 15 elite athletes were able to return to sport effectively and compete at a preoperative level. The mean time between the operation and the first practice was 6.5 months, while the mean time between the ESA procedure and the first game was 9.6 months. Approximately 27.8 months after surgery, PROS outcomes improved significantly with no hips requiring emergency revision surgery at the final follow-up. At a mean of 47.1 months after surgery, 7 athletes decided to retire from their sport. Up to 71.1 months after surgery, the additional 8 patients continued to compete in their sport at an elite level. CONCLUSIONS: ESA enables elite athletes with acetabular dysplasia to return to competition at a mean of 9.6 months postsurgery. The ESA procedure is an effective and promising method of treating elite athletes with acetabular dysplasia. LEVEL OF EVIDENCE: IV.

Incidence and trend of antiresorptive agent-related osteonecrosis of the jaw from 2016 to 2020 in Kure, Japan.

We investigated the incidence/trend of osteonecrosis of the jaw by antiresorptive agent dose over a 5-year period in Kure city, Japan. The incidence was 24 times higher among osteoporosis patients with low-dose agents and 421 times higher among cancer patients with high-dose agents than in the population without agents. PURPOSE: We launched the registry system of osteonecrosis of the jaw (ONJ) cases in 2015 to investigate the trend in ONJ incidence. The purpose of our study was to estimate the ONJ incidence among patients with antiresorptive agent use by dosage and people without antiresorptive agent use in Kure and its trend from 2016 to 2020. METHODS: From 2016 to 2021, 98 eligible ONJ patients were enrolled. Medication-related ONJ (MRONJ) was diagnosed based on the American Association of Oral and Maxillofacial Surgeons criteria. The annual number of those with and without antiresorptive agents was obtained from the claims database. Antiresorptive agents used for cancer and osteoporosis patients were defined as high- and low-dose medications, respectively. RESULTS: The annual incidence of high-dose MRONJ was 2305.8 per 100,000 and that of low-dose MRONJ was 132.5 per 100,000, while the ONJ incidence among people without antiresorptive agents was 5.1 per 100,000. The incidence ratio was 23.6 (p < 0.001, 95% confidence interval (CI) 13.3-41.8) among osteoporosis patients who used low-dose antiresorptive agents and 420.6 (p < 0.001, 95% CI 220.8-801.4) among cancer patients who used high-dose agents compared with people who did not use these agents. MRONJ incidence increased from 2016 to 2020, but the incidence of high-dose MRONJ decreased, although this was nonsignificant. CONCLUSION: We demonstrated the incidence and trend of ONJ by antiresorptive agent dose over a 5-year period in Kure after launching the multiprofession study. This collaborative study for the early detection and prevention of ONJ will continue.

Decrease in osteoporotic fracture in the western Kitakyushu region by the STOP-Fx study.

INTRODUCTION: The Seamless Treatment of Osteoporosis against Fractures (STOP-Fx) study was initiated to provide and continue therapeutic interventions for registered patients with osteoporotic fractures. MATERIALS AND METHODS: Women who visited six hospitals in the western Kitakyushu area for osteoporotic fractures between October 2016 and December 2018 were included in the study. Data collection for primary and secondary outcomes was conducted from October 2018 to December 2020, 2 years after STOP-Fx study enrollment. The primary outcome included the number of surgeries for osteoporotic fractures after the STOP-Fx study intervention, while secondary outcomes were the intervention rate of osteoporosis treatment, incidence and timing of secondary fractures, and factors associated with secondary fractures and loss to follow-up. RESULTS: Concerning the primary outcome, the number of surgeries for osteoporotic fractures decreased since the STOP-Fx study initiation: 813 in 2017, 786 in 2018, 754 in 2019, 716 in 2020, and 683 in 2021. Regarding the secondary outcome, of the 805 patients enrolled, 445 were available for follow-up at 24 months. Of the 279 patients who were untreated for osteoporosis at enrollment, 255 (91%) were on treatment at 24 months. There were 28 secondary fractures, which were associated with increased tartrate-resistant acid phosphatase-5b and decreased lumbar spine bone mineral density during enrollment in the STOP-Fx study. CONCLUSION: As the demographics and medical area served by six hospitals in the western Kitakyushu region have not changed significantly since the STOP-Fx study initiation, the STOP-Fx study may have contributed in decreasing the number of osteoporotic fractures.

Validation of foot plantar pressure sensor data used to estimate standing, sitting, and moving durations in one working day.

BACKGROUND: Maintaining immovable postures for long durations might be a cause of low back pain. However, the relation between low back pain and the maintenance of postures for long durations has been unclear. Therefore, the durations of several postures in one working day should be measured to evaluate the risk of low back pain, although the available measuring methods are limited. To the best of our knowledge, no study has reported the development and investigation of a foot plantar pressure sensor for measurement of standing, sitting, and moving durations in daily work routines. Thus, in this study, we aimed to develop a foot plantar pressure sensor that could withstand long-term loads in the workplace. Furthermore, we aimed to evaluate the estimated results of standing, sitting, and moving durations among factory workers using the developed foot plantar pressure sensor. METHODS: The developed foot plantar pressure sensor obtained a percentage difference within ±5% to estimate standing, sitting, and moving durations in the laboratory. We measured foot plantar pressures of 20 factory workers to estimate standing, sitting, and moving activity in one working day using data obtained by the foot plantar pressure sensor. The estimated standing, sitting, and moving durations were compared with the human estimation of photo data obtained by a wearable camera. RESULTS: The agreement rate (Cohen's kappa coefficient) was 0.75 between the evaluation using the foot plantar pressure sensor data and human estimation using a wearable camera. Cohen's kappa coefficient was 0.81 in subjects who sat for ≥30% during daily work and 0.68 in subjects who sat for <30%. CONCLUSION: Our foot plantar pressure sensor effectively measured the standing, sitting, and moving durations in daily work that requires various movements and assumption of postures.

Validity and application of Doiguchi's pelvic tilt measurement method.

BACKGROUND: The validity of Doiguchi's pelvic tilt measurement method has not been proven. The objective in our study was to validate the method. METHODS: Our investigation included 73 total hip arthroplasties (THAs) performed using our cup placement procedure from July 2020 to November 2021. Pelvic tilt formed by the pubic symphysis and sacral promontory (PTPS) in supine and lateral positions was calculated by two methods (the Doiguchi method and the digital reconstructed radiograph (DRR) method using a 3D computer templating system) based on the transverse and longitudinal diameters of the pelvic ring measured immediately before THA. RESULTS: There was a strong/moderate correlation in the values of PTPS between the Doiguchi and DRR methods. However, the value of PTPS calculated by the Doiguchi method was significantly lower than that calculated by DRR, and there was a partially direct match. On the other hand, there was no significant difference in the value of PT change from supine to lateral position between the Doiguchi and DRR methods. The PT changes based on both methods were strongly correlated, and the PT change calculated by the Doiguchi method was almost identical to that calculated by the DRR method. CONCLUSIONS: Doiguchi's pelvic tilt measurement method was validated for the first time. These results demonstrated that the ratio of the transverse and longitudinal diameters of the pelvic ring was an important factor defining the change in pelvic tilt. The slope in the linear function of the Doiguchi method was found to be almost the correct value, although the intercept of the linear function exhibited individual differences.

Development of a novel knee contracture mouse model by immobilization using external fixation.

AIMS: Several studies have used animal models to examine knee joint contracture; however, few reports detail the construction process of a knee joint contracture model in a mouse. The use of mouse models is beneficial, as genetically modified mice can be used to investigate the pathogenesis of joint contracture. Compared to others, mouse models are associated with a lower cost to evaluate therapeutic effects. Here, we describe a novel knee contracture mouse model by immobilization using external fixation. METHODS: The knee joints of mice were immobilized by external fixation using a splint and tape. The passive extension range of motion (ROM), histological and immunohistochemical changes, and expression levels of fibrosis-related genes at 2 and 4 weeks were compared between the immobilized (Im group) and non-immobilized (Non-Im group) groups. RESULTS: The extension ROM at 4 weeks was significantly lower in the Im group than in the Non-Im group (p < 0.01). At 2 and 4 weeks, the thickness and area of the joint capsule were significantly greater in the Im group than in the Non-Im group (p < 0.01 in all cases). At 2 weeks, the mRNA expression levels of the fibrosis-related genes, except for the transforming growth factor-ß1, and the protein levels of cellular communication network factor 2 and vimentin in the joint capsule were significantly higher in the Im group (p < 0.01 in all cases). CONCLUSION: This mouse model may serve as a useful tool to investigate the etiology of joint contracture and establish new treatment methods.

Oxidative stress causes muscle structural alterations via p38 MAPK signaling in COPD mouse model.

INTRODUCTION: Sarcopenia is a complication of Chronic Obstructive Pulmonary Disease (COPD) that negatively affects physical activity and quality of life. However, the underlying mechanism by which COPD affects skeletal muscles remains to be elucidated. Therefore, we investigated the association between oxidative stress and structural alterations in muscles in elastase-induced emphysema mouse models. MATERIALS AND METHODS: Twelve-week-old male C57BL/6J mice were treated with either intratracheal porcine pancreatic elastase (PPE) dissolved in saline, or saline alone. The mice were euthanized 12 weeks after treatment, and the lungs and limb muscles were used for protein analysis of oxidative stress, p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway and muscle atrophy signaling pathway related with oxidative stress. Furthermore, C57BL/6J mice treated with PPE or saline were analyzed for the effects of oral administration of astaxanthin or p38 inhibitor. RESULTS: The weight of the soleus muscle, proportion of type I muscle fibers, and cross-sectional areas of muscle fibers in the PPE group were lower than those in the control group. Oxidative stress marker levels in the PPE group were elevated in skeletal muscles. The p38 MAPK signaling pathway was activated in the soleus muscles, leading to the activation of the ubiquitin-proteasome system and autophagy. Astaxanthin and p38 inhibitors attenuated alterations in muscle structure through the deactivation of the p38 MAPK signaling pathway. CONCLUSIONS: This study provides first evidence in COPD mouse model that oxidative stress trigger a series of muscle structural changes. Our findings suggest a novel target for sarcopenia in COPD.

Deficiency of Wnt10a causes female infertility via the ß-catenin/Cyp19a1 pathway in mice.

Wnt signaling is relevant for a wide range of biological processes, including reproductive function. The function of Wnt10a in female fertility, however, remains obscure. In the present study, we explored the structure and function of the female reproductive organs in Wnt10a knockout (KO) mice. The expression of ß-catenin signaling was significantly lower in the ovaries of the Wnt10a KO mice compared with wild-type (WT) mice. In addition, the estrous cycles were disrupted, ovarian follicles were diminished, and endometria were thinner, accompanied by lower serum estrogen levels, and higher testosterone and progesterone levels in Wnt10a KO mice. The expression of the ovarian cytochrome P450 family 19 subfamily A member 1 (Cyp19a1) was significantly lower in Wnt10a KO mice. We detected no significant changes in the levels of the gonadotropins between WT and KO mice. Together, our findings indicate that deficiency of Wnt10a causes female infertility through ß-catenin and Cyp19a1signaling pathways in mice.

Accurate cup placement using a portable navigation system during total hip arthroplasty based on pelvic orientation in the lateral decubitus position.

BACKGROUND: We previously proposed an accurate cup placement procedure using a portable navigation system (PNS) for total hip arthroplasty (THA) in the lateral decubitus position; however, the accuracy of our proposed procedure has not been shown, the aim of this study was to demonstrate the accuracy. METHODS: We prospectively analyzed 79 hips treated with primary THA; 40 hips treated until June 2020 were included in the conventional procedure (CP) group, and 39 hips treated from July 2020 were included in the modified procedure (MP) group. In the MP, pelvic orientation is considered to be the set coordinate axes in addition to the CP using the PNS. The accuracy was based on the difference between the navigation record (NR) and postoperative computed tomography measurement. RESULTS: The radiographic inclination (RI) and anteversion (RA) accuracies were 1.55° and 2.14°, respectively, in the MP group and 3.03° and 6.20°, respectively, in the CP group (p < 0.001). The error was within 5° of the NR for both the RI and RA in 34 in the MP group (87.2%) and 14 in the CP group (35.0%) (p < 0.001). The error was within 5° of the target angle (RI 40°, RA 15°) for both the RI and RA in 29 hips in the MP group (74.7%) and 12 in the CP group (30.0%) (p < 0.001). CONCLUSIONS: Our procedure with the consideration of pelvic orientation achieved dramatically improved the accuracy of PNS and was suitable to facilitate accurate cup placement.

Trabecular Bone Volume Is Reduced, With Deteriorated Microstructure, With Aging in a Rat Model of Duchenne Muscular Dystrophy.

We aimed to clarify the effect of aging on trabecular bone volume and trabecular bone microstructure in a rat model of Duchenne muscular dystrophy (DMD). Six rats each of wild type (WT) and DMD model at 15 weeks of age, and 4 rats each at 30 weeks of age, were analyzed by dual energy X-ray absorptiometry and by micro-CT for analysis of trabecular and cortical bone of the femur. Bone mineral density was significantly lower in the DMD group than in the WT group at both 15 and 30 weeks of age. Micro-CT showed that trabecular bone volume and number were not significantly different between the two groups at 15 weeks, but at 30 weeks both were significantly lower in the DMD group than in the WT group. Connectivity density and structure model index were not significantly different between the two groups at 15 weeks, but at 30 weeks they differed significantly. No significant differences between the WT and DMD groups in cortical thickness and cortical area were evident at both 15 and 30 weeks. In conclusion, trabecular bone volume is significantly reduced, with deteriorated microstructure, with aging in a rat model of DMD.

Zoledronic acid sequential therapy could avoid disadvantages due to the discontinuation of less than 3-year denosumab treatment.

INTRODUCTION: Rapid descent in bone mineral density (BMD) and ascent in bone turnover marker (BTM) occur within the short period following denosumab (Dmab) discontinuation. In addition, the incidence of vertebral fracture also rises within the short period. The purpose of this study is to investigate the effects of sequential therapy using zoledronic acid (ZOL) on any adverse events after Dmab discontinuation. MATERIALS AND METHODS: This study was a multicenter retrospective observational study, and the subjects were osteoporosis patients who visited our institutions between 2013 and 2018. We performed sequential therapy using ZOL for 30 patients who had difficulty continuing Dmab, due to physical or social reasons, and investigated the fracture incidence and BMD/BTM changes at 4 time points (at the start of Dmab, the start of ZOL, 6 months after ZOL and 12 months after ZOL). RESULTS: No new vertebral/nonvertebral fractures were observed at each time point after switching from Dmab to ZOL in any of the 30 patients. The BMD/BTM changes were evaluated in 18 of the 30 cases, since all data of lumbar/femoral neck BMDs and TRACP-5b at 4 time points was only available in 18 cases. BMDs significantly increased at each time point compared with that at the start of Dmab. Serum TRACP-5b significantly decreased at each time point compared with that at the start of Dmab. CONCLUSION: It was suggested that sequential therapy using ZOL could suppress the decrease of BMD, and increase of BTM, if the period of Dmab administration was less than 3 years.

Differentiation Potential of Synovial Mesenchymal Stem Cells Isolated From Hip Joints Affected by Femoroacetabular Impingement Syndrome Versus Osteoarthritis.

PURPOSE: To establish the characteristics of synovium-derived mesenchymal stem cells (MSCs) from the hip joints of patients with femoroacetabular impingement syndrome (FAIS) and osteoarthritis (OA), particularly their proliferation and differentiation potentials. We further investigated their functional differences. METHODS: Synovium samples were harvested from 21 patients with FAIS who underwent hip arthroscopic surgery and from 14 patients with OA who underwent total hip arthroplasty. The MSC number, colony-forming units, cell viability, and differentiation potential were compared. Real-time polymerase chain reaction assessed the differentiation potential into adipose, bone, and cartilage tissues. RESULTS: The number of colonies at a density of 104 at passage 0 from OA synovium was significantly greater than that from FAIS synovium (P < .01). However, their proliferation and viability were significantly lower than those of FAIS synovium cells (P = .0495). The expression of lipoprotein lipase mRNA in OA synovium cells was greater than that in FAIS synovium cells (P < .01). Meanwhile, the fraction of colonies positive for von Kossa and alkaline phosphatase staining, as well as the level of bone gamma-carboxyglutamate protein expression in OA synovium cells, were greater than those in FAIS synovium cells (P < .01). In chondrogenic pellet culture experiments, the expression of COL10A1 mRNA was lower in OA synovium than in FAIS synovium (P < .01). CONCLUSIONS: Synovial MSCs from patients with OA had greater colony numbers but less viability and proliferative potential. They also showed greater osteogenic and adipogenic potentials, whereas those from patients with FAIS showed greater chondrogenic potential. CLINICAL RELEVANCE: MSCs from patients with FAIS exhibited good potential as cell sources for stem cell therapy in case of cartilage damage in the hip joint.

Alpha-Defensin-1 in Synovial Fluid is Useful for Diagnosis of Joint Infection.

The distinction between bacterial infectious and noninfectious arthritis is typically challenging in the early stages; however, it is critical for treatment decision making. Here, we investigated the diagnostic relevance of alpha- and beta-defensin levels in serum and synovial fluid as biomarkers of joint infection in patients presenting with fever and arthritis. The study included 12 patients who presented with fever (≥37°C) and arthritis (pain in the knee or hip joint). The diagnostic criteria for periprosthetic joint infection proposed by the Musculoskeletal Infection Society were used to detect joint infection and categorize the patients into infection and non-infection groups. Alpha-defensin-1 and beta-defensin-3 levels in serum and synovial fluid were measured using enzyme-linked immunosorbent assay. No significant between-group difference was observed with respect to serum alpha-defensin-1 levels; however, synovial fluid alpha-defensin-1 levels were significantly higher in the infection group (33.6 ± 26.2 ng/ml) than in the non-infection group (0.9 ± 0.4 ng/ml). No significant between-group differences were observed with respect to serum or synovial fluid beta-defensin-3 levels. Furthermore, synovial fluid alpha-defensin-1 levels were increased in patients without prosthesis in the infection group. In conclusion, in patients with fever and arthritis, synovial fluid alpha-defensin-1 levels were significantly higher in patients with infectious arthritis than in those with noninfectious arthritis. Therefore, synovial fluid alpha-defensin-1 levels is a useful diagnostic marker for joint infection.

Depletion of WNT10A Prevents Tumor Growth by Suppressing Microvessels and Collagen Expression.

Background: We recently reported that WNT10A plays a pivotal role in wound healing by regulating collagen expression/synthesis, as the depletion of WNT10A dramatically delays skin ulcer formation. WNT signaling also has a close correlation with the cancer microenvironment and proliferation, since tumors are actually considered to be 'unhealing' or 'overhealing' wounds. To ascertain the in vivo regulatory functions of WNT10A in tumor growth, we examined the net effects of WNT10A depletion using Wnt10a-deficient mice (Wnt10a -/-). Methods and Results: We subjected C57BL/6J wild-type (WT) or Wnt10a -/- mice to murine melanoma B16-F10 cell transplantation. Wnt10a -/- mice showed a significantly smaller volume of transplanted melanoma as well as fewer microvessels and less collagen expression and more necrosis than WT mice. Conclusions: Taken together, our observations suggest that critical in vivo roles of Wnt10a-depleted anti-stromagenesis prevent tumor growth, in contrast with true wound healing/scarring.

Short-term efficacy and safety of collagenase injection for Dupuytren's contracture: Therapy protocol for successful outcomes in a clinical setting.

PURPOSE: To assess the short-term efficacy and safety of collagenase injection for Dupuytren's contracture and of our post-injection therapy protocol alternative the instruction of phase III studies at clinical setting. METHODS: The retrospective study included 23 fingers of 21 hands of 18 patients for primary metacarpophalangeal (MP) joints and 11 fingers of 10 hands of 10 patients for primary proximal interphalangeal (PIP) joints with Dupuytren's contracture who were treated with 0.58 mg collagenase Clostridium histolyticum (CCH) injections at our hospital consecutively from September 2015 to October 2017. The mean age of the patients was 73.0 years (range, 57-88) for primary MP joints and 70.7 years (61-81) for primary PIP joints. Following standard CCH injection and manipulation on the next day, certified hand surgeons evaluated and treated each patient based on a defined 4-week therapy protocol that consisted of performing finger exercises during the day and wearing static extension splint at night for all cases, and of wearing Capener dynamic splint intervention to address severely contracted PIP joints. We measured the degree of contracture at baseline, immediately, 4 weeks, and 12 weeks after the last manipulation. RESULTS: More improvement of contracture was seen in the MP joints than in the PIP joints. For the five fingers severely contracted and treated with Capener splint intervention, the mean passive PIP joint contracture was 62.0° at baseline, 21.0° immediately, further improved to 6.0° by 4 weeks, and maintained 8.0° by 12 weeks after the last manipulation. The adverse events were mild-to-moderate local reactions in the injected hand. CONCLUSIONS: The clinical efficacy and safety of CCH were confirmed in a clinical setting similar to phase III studies. The improvement of 4-week-intervention was maintained at 12 weeks after the last manipulation. Severely contracted PIP joints could benefit from Capener splint intervention.

Case Report and Literature Review of Periprosthetic Atypical Femoral Fractures After Total Hip Arthroplasty.

We describe a case of periprosthetic femoral fracture with 5 major features of an atypical femoral fracture (AFF) and localized cortical thickening at the fracture site, which is characteristic of an AFF. An 81-year-old female patient had undergone cementless total hip arthroplasty for a right femoral neck fracture at the age of 66, and had been taking oral alendronate since then. At the age of 79, she developed spontaneous right thigh pain. Radiographs showed lateral cortical thickening and pedestal formation around the end of the femoral component. She was advised to discontinue oral alendronate and change to eldecalcitol. At the age of 81, she developed sudden severe pain when standing up from a seated position and was not able to walk. Radiographs showed a periprosthetic femoral fracture with 5 major features of AFF at the site of localized cortical thickening. We diagnosed a Vancouver type B1 periprosthetic femoral fracture. She underwent open reduction and internal fixation (ORIF) with an NCB® Periprosthetic Femur Plate System with cable grips. Daily subcutaneous injection of teriparatide and low intensity pulsed ultrasound therapy were performed to stimulate bone healing. She was able to walk without assistance at 4 months after ORIF. Radiographs showed adequate bridging callus and a disappearing fracture line. This case was diagnosed as a periprosthetic atypical femoral fracture (PAFF), because a periprosthetic fracture is excluded from the definition of AFF. Similar to AFF, PAFF exhibits poor clinical outcomes. The approach to treating PAFF should be decided after considering the pathogenesis.

Rapidly Progressive Osteolysis and a Large Cystic Lesion that Destroyed the Inner Table of the Iliac Bone Following Cementless Total Hip Arthroplasty: A Case Report.

We report a case of rapidly progressive osteolysis and a very large cystic lesion that destroyed the inner table of the iliac bone following cementless total hip arthroplasty (THA). A 59-year-old female patient developed left hip pain at 11 years after THA. Osteolysis surrounding the acetabular cup was pointed out. She was brought to our hospital by ambulance due to severe left hip pain at 12 years after THA. Computed tomography (CT) showed that a cystic lesion in the pelvic cavity had destroyed the inner table of the iliac bone. Magnetic resonance imaging (MRI) showed a high signal intensity area of the hemorrhagic cystic lesion in the iliac bone in both T1-weighted and T2-weighted images. She underwent a liner and femoral head exchange, and required bone grafting and revision of the cup. The cystic lesion was removed and block-like allograft bone grafts were stuffed into the bone defects. If osteolysis and cystic lesions occur at the same time, not only the bone area around the implant but also a distant area like the inner table of the iliac bone may be destroyed. Additional tests such as CT or MRI may be useful to detect the presence of distant or cystic lesions. Early diagnosis and treatment are important because severe complications may occur in cases where osteolysis and cystic lesions coexist after THA.

Disruption of the Aldehyde Dehydrogenase 2 Gene Results in No Increase in Trabecular Bone Mass Due to Skeletal Loading in Association with Impaired Cell Cycle Regulation Through p21 Expression in the Bone Marrow Cells of Mice.

Approximately 45% of people of East Asian descent have the inactive aldehyde dehydrogenase 2 (ALDH2) phenotype. The enzyme defect of ALDH2 has been found to adversely influence the risk of osteoporosis. The aim of this study was to clarify the effect of skeletal loading on trabecular bone structure and dynamics in Aldh2-disrupted mice in the absence of alcohol consumption. Four-week-old male Aldh2-/- (KO) and Aldh2+/+ (WT) mice were divided into a ground control (GC) group and a climbing exercise (CE) group in each genotype. The trabecular bone mineral density of the distal femur measured by peripheral quantitative computed tomography in the wild-type CE (WTCE) group was significantly higher than that in the wild-type GC (WTGC) group; however, there was no significant difference between the knockout CE (KOCE) and knockout GC (KOGC) groups. Bone histomorphometry revealed that osteogenic parameters were significantly increased in the WTCE group compared with the WTGC group, but not increased in the KOCE group compared with the KOGC group. Quantitative reverse transcriptase polymerase chain reaction and flow cytometry revealed that mRNA and protein expression levels of p21 were significantly decreased in the WTCE group compared with those in the WTGC group, while these differences were not observed between the KOGC and KOCE groups. This study provides the first in vivo evidence that p21 expression in the bone marrow is not decreased after skeletal loading and osteoblast differentiation is impaired in the absence of Aldh2 gene.

Highly Cross-Linked Polyethylene Reduces Osteolysis Incidence and Wear-Related Reoperation Rate in Cementless Total Hip Arthroplasty Compared With Conventional Polyethylene at a Mean 12-Year Follow-Up.

BACKGROUND: A number of studies on total hip arthroplasty have compared highly cross-linked polyethylene (HXLPE) with conventional polyethylene (CPE) liners beyond 10 years. However, the impact of HXLPE on the wear-related reoperation rate is unclear. The purpose of this study was to evaluate the clinical advantage of using a single manufacturer's HXLPE in terms of reducing the reoperation rate. METHODS: The study was a follow-up retrospective cohort study over a mean of 12 years that examined patients aged 45-70 years with cementless total hip arthroplasty using a 26-mm-diameter cobalt-chromium head. Sixty-seven patients (79 hips; HXLPE group = 41 hips, CPE group = 38 hips) were evaluated for a minimum 10-year follow-up. Kaplan-Meier survival analysis was performed, with wear-related reoperations and radiographic osteolysis serving as the end points. The polyethylene wear rate was also assessed. RESULTS: The mean 12-year follow-up rates of survivorship that were evaluated using wear-related reoperations as the end point were 100% and 91.4% in the HXLPE and CPE groups, respectively (P = .007), and the mean 12-year follow-up rates of survivorship with osteolysis as the end point were 100% and 36.2%, respectively (P < .001). Compared with the CPE group, the HXLPE group presented a significantly reduced wear rate (HXLPE group, 0.035 mm/y; CPE group, 0.118 mm/y). CONCLUSION: A unique strength of this study is that we assessed a single manufacturer's HXLPE while keeping most other implant parameters uniform. This study reveals the clinical advantage of using a single manufacturer's HXLPE in terms of a reduced wear-related reoperation rate at a mean 12-year follow-up.