Axial loading of the foot/ankle complex is an important injury mechanism in vehicular trauma that is responsible for severe injuries such as calcaneal and tibial pilon fractures. Axial loading may be applied to the leg externally, by the toepan and/or pedals, as well as internally, by active muscle tension applied through the Achilles tendon during pre-impact bracing. The objectives of this study were to investigate the effect of Achilles tension on fracture mode and to empirically model the axial loading tolerance of the foot/ankle complex. Blunt axial impact tests were performed on forty-three (43) isolated lower extremities with and without experimentally simulated Achilles tension. The primary fracture mode was calcaneal fracture in both groups. However, fracture initiated at the distal tibia more frequently with the addition of Achilles tension (p < 0.05). Acoustic sensors mounted to the bone demonstrated that fracture initiated at the time of peak local axial force. A survival analysis was performed on the injury data set using a Weibull regression model with specimen age, gender, body mass, and peak Achilles tension as predictor variables (R2 = 0.90). A closed-form survivor function was developed to predict the risk of fracture to the foot/ankle complex in terms of axial tibial force. The axial tibial force associated with a 50% risk of injury ranged from 3.7 kN for a 65 year-old 5th percentile female to 8.3 kN for a 45 year-old 50th percentile male, assuming no Achilles tension. The survivor function presented here may be used to estimate the risk of foot/ankle fracture that a blunt axial impact would pose to a human based on the peak tibial axial force measured by an anthropomorphic test device.

We reviewed evidence on total wrist replacement from the last 5 years. Eight articles met a minimum set standard. The results of 405 prostheses were available, including seven different manufacturers. The mean follow up was 2.3-7.3 years with an average age of 52-63. Rheumatoid arthritis was the indication in 42% of patients. Motec demonstrated the best post-operative DASH scores. Only Maestro achieved a defined functional range of motion post-operatively. Universal 2 displayed the highest survival rates (100% at 3-5 years), while Elos had the lowest (57% at 5 years). Biaxial had the highest complication rates (68.7%), while Remotion had the lowest (11%). Wrist arthroplasty preserves some range of motion. Functional scores improved and were maintained over the mid- to long-term. Complication rates were higher than wrist fusion, with reports of radiological loosening and osteolysis. The evidence does not support the widespread use of arthroplasty over arthrodesis, and careful patient selection is essential.

We retrospectively compared the short-term outcomes of 18 thumbs that had a trapeziectomy and 18 that had a pyrocarbon interposition implant (Pi2) arthroplasty in 33 patients. We measured the Disability of the Arm, Shoulder, and Hand (DASH) and Short Form 36 (SF-36) scores at a mean of 20 months. Pain severity was assessed using a visual analogue scale (VAS), and level of patient satisfaction was assessed using a 5-point scale. The mean DASH scores at follow up were 27 for those that had a trapeziectomy and 35 for those that had a Pi2 arthroplasty (p = 0.001). There was no difference in the VAS for pain, SF-36 scores, or other parameters assessed. Six out of 18 (33%) thumbs in the Pi2 group had multiple operations, usually for dislocation or subluxation of the implant. The early results of Pi2 arthroplasty show a high complication rate compared with trapeziectomy and no identifiable benefit.

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