Scaffold-Free Bone Marrow-Derived Mesenchymal Stem Cell Sheets Enhance Bone Formation in a Weight-Bearing Rat Critical Bone Defect Model.

Researchers have been exploring alternative methods for bone tissue engineering, as current management of critical bone defects may be a significant challenge for both patient and surgeon with conventional surgical treatments associated with several potential complications and drawbacks. Recent studies have shown mesenchymal stem cell sheets may enhance bone regeneration in different animal models. We investigated the efficacy of implanted scaffold-free bone marrow-derived mesenchymal stem cell (BMSC) sheets on bone regeneration of a critical bone defect in a weight-bearing rat model. BMSCs were isolated from the femora of male Sprague-Dawley rats 5-6 weeks of age and cell sheets were produced on temperature-responsive culture dishes. Nine male Sprague-Dawley rats 6-8 weeks of age were utilized. A bilateral femoral critical bone defect was created with a bridge plate serving as internal fixation. One side was randomly selected and BMSC sheets were implanted into the bone defect (BMSC group), with the contralateral side receiving no treatment (control). Rats were anesthetized and radiographs were performed at 2-week intervals. At the 8-week time point, rats were euthanized, femurs harvested, and microcomputed tomography and histological analysis was performed. We found a statistically significant increase in new bone formation and bone volume fraction compared with the control. Histomorphometry analysis revealed a larger percent of newly formed bone and a higher total histological score. Our results suggest that scaffold-free BMSC sheets may be used in the management of large weight-bearing bone defects to complement a different surgical technique or as a standalone approach followed by internal fixation. However, further research is still needed.

Early functional recovery after two-stage surgery with an allogenic bone graft for baseplate loosening in reverse shoulder arthroplasty: a case report.

OBJECTIVES: Reverse shoulder arthroplasty (RSA) for cuff tear arthropathy results in good shoulder function. However, RSA is associated with several complications, including infection, dislocation of the shoulder joint, implant loosening, and axillary nerve palsy. Several problems may also occur on the glenoid side, including bone defects of the glenoid, baseplate loosening, and displacement of the sphere. Herein, we report a 79-year-old man who obtained early functional recovery following a two-stage operation with an allogenic bone graft to treat baseplate loosening and a glenoid bone defect after RSA. CASE REPORT: The patient presented with pain during motion and limited active shoulder joint movement 5 weeks after undergoing RSA for cuff tear arthropathy. CT revealed baseplate loosening and a glenoid bone defect; these complications were treated via a two-stage operation. The first stage comprised the removal of all implants and the grafting of allogenic bone from the femoral head into the glenoid defect. Six months later, CT confirmed complete union of the grafted bone and glenoid. The second stage comprised the re-insertion of all implants. Two months after the last operation, the active shoulder range of motion of the affected side was almost identical to that of the contralateral side. CONCLUSION: Good early functional recovery was obtained using a two-stage operation for baseplate loosening after RSA. Allogenic bone grafting was effective in the reconstruction of the glenoid defect.

Mechanical simulation study of postoperative displacement of trochanteric fractures using the finite element method.

BACKGROUND: Femoral trochanteric fractures are common among older adults. In the reduction of trochanteric fractures, acquiring the support of the anterior cortex at the fracture site on lateral view immediately after surgery is important. However, even if the cortical support is acquired, postoperative displacement due to the loss of this support often occurs. This study aimed to investigate local stress distribution in several trochanteric fracture models and to evaluate risk factors for postoperative displacement using the finite element (FE) method. METHODS: Displaced two-fragment fracture models with an angulation deformity at the fracture site and a non-displaced two-fragment fracture model were constructed. The models with an angulation deformity were of two types, one with the proximal fragment directed backward (type A) and the other with the proximal fragment rotated forward from the femoral neck axis (type B). Thereafter, FE models of the femur and a sliding hip screw mounted on a 135° three-hole side-plate were constructed. A 2010-N load was applied to the femoral head, and a 1086-N load was applied to the greater trochanter. Under this condition, the maximum value of the von Mises stress distribution and the amount of displacement of the femoral head vertex in the distal direction were investigated. RESULTS: A larger maximum stress value at the medial femoral neck cortex and a higher amount of displacement in the distal direction were particularly recognized in type A models. These results indicate that microstructural damage was larger in type A models and that type A fracture alignment may be particularly related to fracture collapse and subsequent postoperative displacement. CONCLUSION: Even if support of the anterior cortex at the fracture site on lateral view is acquired immediately after surgery, caution is necessary for cases in which the proximal fragment is directed backward in the postoperative displacement from the viewpoint of the biomechanics of the FE method.

The nicotinic acetylcholine receptor α7 subunit is an essential negative regulator of bone mass.

The nicotinic receptor α7nAchR reportedly regulates vagal nerve targets in brain and cardiac tissue. Here we show that nAchR7-/- mice exhibit increased bone mass due to decreased osteoclast formation, accompanied by elevated osteoprotegerin/RANKL ratios in serum. Vagotomy in wild-type mice also significantly increased the serum osteoprotegerin/RANKL ratio, and elevated bone mass seen in nAchR7-/- mice was reversed in α7nAchR/osteoprotegerin-doubly-deficient mice. α7nAchR loss significantly increased TNFα expression in Mac1-positive macrophages, and TNFα increased the osteoprotegerin/RANKL ratio in osteoblasts. Targeting TNFα in nAchR7-/- mice normalized both serum osteoprotegerin/RANKL ratios and bone mass. Administration of nicotine, an α7nAchR ligand, to wild-type mice increased serum RANKL levels. Thus, vagal nerve stimulation of macrophages via α7nAchR regulates bone mass by modulating osteoclast formation.

Cigarette Smoking Is Associated With Cubital Tunnel Syndrome.

INTRODUCTION: The aim of this study was to validate the potential association between cigarette smoking and cubital tunnel syndrome (CubTS). METHODS: One hundred patients with CubTS were compared with 100 controls with ulnar abutment syndrome matched for age, gender, and body mass index. The smoking status was compared between patients and controls using the sign test and the Wilcoxon signed rank test. Conditional logistic regression was used to calculate the association between CubTS and pack-years smoked. RESULTS: A significant association was found between increased pack-years smoked and CubTS. A significant difference in the number of never smokers and ever smokers was observed between the patients with CubTS and controls. The difference in mean pack-years in the patients and controls was highly significant. A dose-dependent association with pack-years was found between patients and controls. CONCLUSIONS: High cumulative cigarette smoking is associated with CubTS. Muscle Nerve 54: 1136-1138, 2016.

Dorsal dislocations of the second to fifth carpometacarpal joints: a case report.

Dislocations involving the four ulnar carpometacarpal joints are rare. These complex dislocations are considered to be due to the application of a hyperflexion force on the metacarpal heads. In the present case, an indirect hyperextension force on the metacarpal bones created a lever-arm effect resulting in rupture of the firm ligament complex of the carpometacarpal joints, inducing complete dislocations of the second to fifth carpometacarpal joints.