Quantification of the wear rate in vitro is now considered an essential step in the development of a new joint replacement prior to clinical trials. However, little research exists around in vitro simulation of wear in the patellofemoral joint (PFJ) despite over 200,000 being implanted annually within the European Union. A method to simulate wear in the laboratory using four input degrees of freedom within the PFJ of total knee replacement (TKR) has been developed. Wear simulation was validated through comparison of functional kinematics and patellar surface damage modes produced in vitro to clinical outcomes. The technique has been shown to replicate the prescribed in vivo kinematics in a reproducible and repeatable manner. The wear scar areas were similar to those found in vivo. However, geometrical measurements of wear were not reliable due to creep and geometry changes. As has been found previously with tibial inserts, geometrical determination of wear volume was not found to be an effective method of comparing wear from simulators and retrievals. Change in volume calculated gravimetrically was seen to be the most repeatable measure of patellar wear in vitro.

To monitor the effect of open carpal tunnel decompression on grip strength in the hand, a prospective study was made of 25 patients undergoing a total of 31 operations. Hand grip, key pinch and pulp-to-pulp pinch strengths were measured pre-operatively and at regular intervals until 1 year following operation. At that time there was no significant difference in the hand grip and pulp-to-pulp pinch strengths compared to their pre-operative values, but the key pinch in females showed a marginally significant reduction (P = 0.04) compared to the pre-operative value.