Based on anatomic studies, it appears that the short head (SH) and long head (LH) of the distal biceps tendons have discreet distal attachments on the radial tuberosity. The SH attaches distally and therefore may function as a stronger flexor, whereas the LH attaches more proximal and ulnar which would make it a greater supinator. The contribution of each of the two heads to flexion and supination has not yet been defined. The rationale of this study was to directly measure the contribution of the SH and LH of the biceps to elbow flexion and forearm supination and provide biomechanical evidence for what is inferred in the anatomical studies. Twelve fresh-frozen cadaveric arms were secured using in vitro elbow simulator, while controlled loads were applied to the individual biceps tendons short and long heads. Isometric supination torque and flexion force were recorded with the forearm in 45 degrees supination, neutral rotation and 45 degrees pronation.Purpose
Method
Unicompartmental knee replacement (UKR) is an established, bone preserving surgical treatment option for medial compartment osteoarthritis (OA). Early revision rates appear consistently higher than those of total knee replacement (TKR) in many case series and consistently in national registry data. Failure with progression of OA in the lateral compartment has been attributed, in part, to surgical technical errors. In this study we used navigation assisted surgery to investigate the effects of improper sizing of the mobile bearing and malrotation of the tibial component on alignment and lateral compartment loading. A total of eight fresh frozen cadaveric lower limbs were used in the study. After thawing overnight, a Brainlab navigation system with an Oxford (Biomet, Inc) medial UKR module was used to capture the native knee anatomy and alignment using a digitizing probe. Following registration, the case was performed with navigation verified neutral cuts and an ideal insert size was selected to serve as a baseline. The bearing thickness was subsequently increased by 2 mm increments to simulate progressive medial joint overstuffing. Excessive tibial internal rotation of 12 was also simulated at each of the intervals. Knee alignment in varus or valgus was recorded in real time for each surgical scenario with the knee in full extension and at 20 of flexion. Lateral compartment peak pressure was measured using a Tekscan pressure map.Purpose
Method
