Previous studies proposed the Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), a receptor expressed in myeloid cells including microglia in brain and osteoclasts in bone, as a link between brain and bone disease. The TREM2 R47H variant is a known risk factor for Alzheimer's disease (AD), the most common form of dementia. To investigate whether altered TREM2 signaling could contribute to bone and skeletal muscle loss, independently of central nervous system defects, we used mice globally hemizygous for the TREM2 R47H variant (TREM2R47H/+), which do not exhibit AD pathology, and wild‐type (WT) littermate control mice. Dxa/Piximus showed bone loss in female TREM2R47H/+ animals between 4 and 13 months of age and reduced cancellous and cortical bone (measured by micro‐computed tomography [μCT]) at 13 months, which stalled out by 20 months of age. In addition, they exhibited decreased femoral biomechanical properties measured by three‐point bending at 13 months of age, but not at 4 or 20 months. Male TREM2R47H/+ animals had decreased trabecular bone geometry but increased ultimate strain and failure force at 20 months of age versus WT. Only male TREM2R47H/+ osteoclasts differentiated more ex vivo after 7 days with receptor activator of nuclear factor κB ligand (RANKL)/macrophage colony‐stimulating factor (M‐CSF) compared to WT littermates. Yet, estrogen receptor alpha expression was higher in female and male TREM2R47H/+ osteoclasts compared to WT mice. However, female TREM2R47H/+ osteoclasts expressed less complement 3 (C3), an estrogen responsive element, and increased protein kinase B (Akt) activity, suggesting altered estrogen signaling in TREM2R47H/+ cells. Despite lower bone volume/strength in TREM2R47H/+ mice, skeletal muscle function measured by plantar flexion and muscle contractility was increased in 13‐month‐old female mutant mice. Overall, these data demonstrate that an AD‐associated TREM2 variant can alter bone and skeletal muscle strength in a sex‐dimorphic manner independent of central neuropathology, potentially mediated through changes in osteoclastic intracellular signaling. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
Case: We report the case of a healthy 17-year-old female softball player with a subacute full-thickness intramuscular tear of the pectoralis major (PM) muscle. A successful muscle repair was obtained using a modified Kessler technique.Conclusions: Despite initially being a rare injury pattern, the incidence of PM muscle rupture is likely to increase as interest in sports and weight training increases, and although this injury pattern is more common in men, it is becoming more common in women as well. Furthermore, this case presentation provides support for operative treatment of intramuscular ruptures of the PM muscle. Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C38).
Purpose: To evaluate the safety and efficacy of hip arthroscopy immediately following gunshot wound (GSW) to the hip. Methods: Patients who received hip arthroscopy for GSWs from 2006 to 2020 by 2 surgeons at a level I trauma center were identified by Current Procedural Terminology codes. Inclusion criteria were those patients who suffered a GSW to the hip, received hip arthroscopy for treatment, and had a minimum follow-up of 2 months. The exclusion criteria were any patients younger than 18 years of age. Medical records were reviewed for patient demographics, surgical details, clinical outcomes, and complications. Results: A total of 50 hip arthroscopy cases were identified by Current Procedural Terminology codes. Of the 50 cases identified, 8 patients met the inclusion criteria. All 8 patients were male, African-American, and the mean age was 31 years (range, 19-54 years) with mean follow-up of 14 months. Five of 8 cases were noted to have poor visualization with arthroscopy. Common reasons for poor visualization were difficult access to the bullet fragments, morbid obesity, hematoma formation, and pre-existing arthritis. Of these 5 cases, 2 were converted to open procedures to retrieve the remaining bullet fragments. One patient developed abdominal compartment syndrome, most likely due to increased pulse pressure over a prolonged operative period and involvement of the acetabular fovea. Emergent exploratory laparotomy and abdominal compartment fluid release were performed, and the patient had an otherwise unremarkable hospital course. Conclusions: There are risks with the use of arthroscopic methods to remove GSW fragments, which may be greater than elective hip arthroscopy. Certain factors, such as the surgeon's arthroscopic experience, locations of bullets fragments, visual quality, length of procedure, and concomitant acetabular fractures, must be considered before proceeding with arthroscopy. Level of Evidence: Therapeutic case series.G unshot wounds (GSWs) to the hip are uncommon, typically causing articular damage and shrapnel retained within the joint. If not removed, these fragments subject the patient to an increased risk of arthritis secondary to third-body wear, chondrotoxicity from metal particles, and mechanical pain. 1 Open arthrotomy for shrapnel removal has been the procedure of choice for many years, but in 1998
Traumatic knee dislocations are complex injuries that can be associated with compromise of the neurovascular structures about the knee.Various classification systems for knee dislocations exist in the literature but should be used with caution as a prognostic tool because many knee dislocations fit into more than 1 category.Special populations of knee dislocations, such as obese patients and high-velocity mechanism injuries, require additional caution during the initial evaluation for possible vascular injuries.
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