Conventionally, patellar tendon-bearing (PTB) sockets, which need high dexterity of prosthetist, are widely used. Lack of chartered and experienced prosthetist has often led to painful experience of wearing prosthesis and this will in turn deter the patients to wear the prosthesis, which will further aggravate stump shrinkage. Thus, the hydrostatic socket which demands relatively lower level of fabricating skill is proposed to replace the PTB socket in order to produce the equivalent, if not better, quality of support to the amputee patients. Both sockets' pressure profiles are studied and compared using finite element analysis (FEA) software. Three-dimensional models of both sockets were developed using MIMICS software. The analysis results showed that hydrostatic socket did exhibit more uniform pressure profiles than that of PTB socket. PTB socket showed pressure concentration near the proximal brim of the socket and also at the distal fibula. It was also found that the pressure magnitude in hydrostatic socket is relatively lower than that of PTB socket.
The purpose of this investigation was to vary the load on the patellar tendon bar and to study the subsequent effect this has on the pattern of the pressure distribution at the stump-socket interface. Ten male subjects from the Southern General Hospital in Glasgow, UK participated in this study. Measuring systems utilising strain gauge and electrohydraulic technologies were designed, developed and constructed to enable pressure measurements to be conducted. One transducer, the patellar tendon (PT) transducer, was attached to the patellar tendon bar of the socket such that the patellar tendon bar was capable of being translated by +/-10 mm towards or away from the tendon. The results of this study showed that the position of the patellar tendon bar had no significant effect on the pressure distribution around the socket indicating that it is an unnecessary feature, which, we propose, may be eliminated during manufacture of a trans-tibial socket.
Post-traumatic severe patella infera and intra-articular adhesion may lead to a severe knee stiffness. We report a 29-year-old man, a muslim prayer leader, who had a previous knee injury. He presented with knee movement from ten degrees to 30 degrees, patellar infera with a length of patella to length of patellar tendon ratio of 2:5, and severe knee arthrofibrosis. He underwent incision of the patella ligament and open arthrofibrosis release, leaving a tendon gap and skin defect of 5 cm. Reconstruction was successfully done using a free vascularised composite tensor fascia lata flap. He regained full range of knee motion with normal strength quadriceps mechanism at five months after surgery, and remained in full function at 18 months follow-up.