Reported models of joint contracture fail to result in severe motion loss. Our purpose was to develop a rabbit model of knee contracture and compare it to another well-accepted model to determine if more severe stiffness can be achieved. Sixteen skeletally mature New Zealand White female rabbits had their right knee operated to create 3-mm defects on the noncartilaginous portions of the femoral condyles, hyperextend the joint to disrupt the posterior capsule, and immobilize the joint in maximum flexion with a Kirschner-wire for 8 weeks (group I). Sixteen additional rabbits were operated on using an identical protocol except for the absence of capsular injury (group II). In each group, mechanical testing was performed at the time of Kirschner-wire release in eight animals, and 16 weeks after remobilization in eight animals. At immobilization release, the average contracture was 76 AE 248 in group I versus 20 AE 108 in group II (p < 0.001). Sixteen weeks after remobilization, the mean contracture was 49 AE 158 group I versus 11 AE 108 in group II (p < 0.001). When associated with bone perforations and immobilization in forced flexion, injury to the posterior capsule results in a severe contracture in the rabbit knee. ß

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Patients with a mean postoperative blood glucose of >200 mg/dL or a preoperative hemoglobin A1C level of >6.7% are at increased risk for wound complications following elective primary total joint arthroplasty. These results show that poor preoperative and postoperative glucose control is independently associated with wound complications.

Given the higher recurrence rate with curettage, patients with aggressive proximal fibula tumors benefit from en bloc resection. The overall morbidity is low, but postoperative permanent peroneal palsy remains a concern (3%).

Studies have demonstrated increased myofibroblasts in contractures. However, the timeline is largely unknown. The aim of this study was to determine the number of myofibroblasts in contracting joint capsules at 3-time points over a 24-week period. Eighteen rabbits subjected to a surgical procedure designed to elicit a knee joint contracture were divided into three groups of six. Rabbits were sacrificed at each respective time point and myofibroblasts in the joint capsules were quantified using immunohistochemistry. The percent of myofibroblasts was significantly elevated in the operated limbs compared to the control limbs at 2 weeks (20% vs. 7%, respectively; p ¼ 0.014). There was no difference in the percent of myofibroblasts between the operated and control limbs at 8 or 24 weeks (p ¼ 0.96 and 0.07, respectively). The percent of myofibroblasts dropped from 20% at 2 weeks to 3.0% at 8 weeks (p < 0.001). The decrease from 8 to 24 weeks was not significant (p ¼ 0.19). A large proportion of myofibroblasts are present in contracted joints at 2 weeks. By week 8, the proportion of myofibroblasts seem to return to normal. Interventions aimed at affecting the myofibroblast cell in order to prevent fibrosis should be instituted early. ß