Load-to-failure characteristics of patellar tendon allograft superior capsule reconstruction compared with the native superior capsule.

BACKGROUND: The potential use of a patellar tendon allograft for superior capsular reconstruction has been demonstrated biomechanically; however, there are concerns regarding compromised fixation strength owing to the longitudinal orientation of the fibers in the patellar tendon. Therefore, the purpose of this study was to compare the fixation strength of superior capsule reconstruction using a patellar tendon allograft to the intact superior capsule. METHODS: The structural properties of the intact native superior capsule (NSC) followed by superior capsular reconstruction using a patellar tendon allograft (PT-SCR) were tested in eight cadaveric specimens. The scapula and humerus were potted and mounted onto an Instron testing machine in 20 degrees of glenohumeral abduction. Humeral rotation was set to achieve uniform loading across the reconstruction. Specimens were preloaded to 10 N followed by cyclic loading from 10 N to 50 N for 30 cycles, then load to failure at a rate of 60 mm/min. Video digitizing software was used to quantify the regional deformation characteristics. RESULTS: During cyclic loading, there was no difference found in stiffness between PT-SCR and NSC (cycle 1 - PT-SCR: 12.9 ± 3.6 N/mm vs. NSC: 22.5 ± 1.6 N/mm; P = .055 and cycle 30 - PT-SCR: 27.3 ± 1.4 N/mm vs. NSC: 25.4 ± 1.7 N/mm; P = .510). Displacement at the yield load was not significantly different between the two groups (PT-SCR: 7.0 ± 1.0 mm vs. NSC: 6.5 ± 0.3 mm; P = .636); however, at the ultimate load, there was a difference in displacement (PT-SCR: 20.7 ± 1.1 mm vs. NSC: 8.1 ± 0.5 mm; P < .001). There was a significant difference at both the yield load (PT-SCR: 71.4 ± 2.2 N vs. NSC: 331.6 ± 56.6 N; P = .004) and the ultimate load (PT-SCR: 217.1 ± 26.9 N vs. NSC: 397.7 ± 62.4 N; P = .019). At the yield load, there was a difference found in the energy absorbed (PT-SCR: 84.4 ± 8.9 N-mm vs. NSC: 722.6 ± 156.8 N-mm; P = .005), but no difference in energy absorbed was found at the ultimate load. CONCLUSIONS: PT-SCR resulted in similar stiffness to NSC at lower loads, yield displacement, and energy absorbed to ultimate load. The ultimate load of the PT-SCR was approximately 54% of the NSC, which is comparable with the percent of the ultimate load in rotator cuff repair and the intact supraspinatus at time zero.

Carpometacarpal Fracture-Dislocations: A Retrospective Review of Injury Characteristics and Radiographic Outcomes.

Background: The purpose of this study was to evaluate the demographics and early radiographic treatment outcome of patients with carpometacarpal (CMC) injuries at our institution over a 10-year period. Methods: We conducted a retrospective review of all patients who sustained CMC injuries of the second to fifth digits between 2005 and 2015. We recorded demographic data, mechanisms of and associated injuries, treatment methods, and complications. Injury and intraoperative and postoperative radiographs were evaluated, and the adequacy of reduction was determined on lateral radiographs of the hand using a grading system that we developed. Results: Eighty patients were included in this study. Delivering a blow with a closed fist was the most common mechanism of injury; however, high-energy mechanisms also made up a large percentage of those included. Injuries to the fourth and fifth CMC joints were most common, and these were frequently associated with fractures of the metacarpal bases and distal carpal row. Closed reduction and percutaneous pinning offered a higher percentage of patients with concentric reduction at the time of pin removal. Time to surgery was significantly different between those with concentric reduction and those with residual subluxation. Conclusion: The most common mechanism of CMC injuries was blow with a closed fist; however, these injuries can be associated with high-energy mechanisms. Fractures of the metacarpal base and distal carpal row are commonly seen with these injuries. With early diagnosis, closed reduction and percutaneous pinning achieved concentric radiographic reduction. Delayed diagnosis makes closed reduction difficult and was associated with less favorable radiographic outcome.

Editorial Commentary: Hip Joint Space as a Predictor of Cartilage Pathology: A Basic Tool for a Complex Task.

Predicting articular cartilage pathology in the hip with radiographic joint space has been unreliable for patients having joint spaces >2 mm in width. Joint space width is a tool that can be used, but with some limitation. Other methods of investigation such as magnetic resonance imaging should be used in conjunction with radiographic joint space.

Distal Radius Fracture Fixation Devices and Their Radiographs.

Background: Distal radius fractures are among the most common fractures encountered in orthopedic practices. If treated operatively, most implants are retained after the fracture heals unless there is hardware failure, limitation of wrist motion, pain, infection, tendon rupture, or tenosynovitis. Complications have been reported during hardware removal, including not knowing the exact implant prior to its removal. If a patient presents for plate removal to a surgeon who did not perform the initial fracture fixation, having a preoperative visual aid can help the treating surgeon choose the right instruments for their removal. Methods: To identify many of the available distal radius fixation devices, we searched the Internet and contacted local industry representatives. We also approached industry personnel at the commercial exhibit of a national hand society meeting to provide us with implants they manufacture. The implants were placed on the volar and dorsal aspects of sawbone models of the distal radius and in one case the radial styloid, using the screws, screwdrivers and accessories in the standard implant set and then posteroanterior and lateral x-rays of the implants were obtained. We created an atlas and a list of the screwdriver(s) used for each. Results: We obtained radiographs and photographs for 28 implants that were manufactured by 14 different companies. Two companies sent us radiographs and photographs placed on either a sawbone or cadaveric model. We found that 7 of the implants were outliers and could be identified easily on the x-rays, whereas 21 implants had similar design of shaft and distal components. Conclusions: To aid the orthopedic surgeon in their removal, we compiled a comprehensive list of most distal radius fixation devices on the market including plates and their corresponding screws and screwdrivers. The goal was to help the surgeon when removing the plate to identify the implant on radiographs.