Post-market surveillance is necessary to ensure the safety and efficacy of newly introduced technologies and implants. The Birmingham Hip Resurfacing (Smith and Nephew, Inc., Memphis, TN) was the first hip resurfacing implant approved for use by the US FDA in May 2006. A prospective, multi-center postmarket approval study has been in progress to assess safety and efficacy of this implant. Patients meeting inclusion criteria were enrolled at five sites. Clinical evaluation and radiographs were obtained at 3 months and 1 year, and annually thereafter for a total of 10 years. Blood metal ion levels were measured at 1 year and 4 years.Background
Methods
Our aim was to evaluate the functional outcome of extensile revision knee exposure techniques. 166 revision total knee arthroplasties requiring an extensile exposure with 2 year minimum follow-up were prospectively studied {81 rectus snips (RS), 42 tibial tubercle osteotomies (TTO), and 43 quadriceps turn-downs (QT)}. Patients were clinically evaluated for knee society score, range of motion (ROM) and extensor lag comparing pre-op and 24 month follow-up appointment findings. Radiological evidence of avascular necrosis (AVN) pre &
post operation was recorded. The TTO group was further examined for proximal migration of the tubercle post op. Pre-operative knee motion (75° &
71°) and knee scores (74 &
70) were lower in revision total knee arthroplasties requiring QT &
TTO than those requiring a RS (91° &
84). Post op flexion and knee scores were greater in the RS group (102° &
131) than in the QT (81° &
114) and TTO (84° &
111) groups in whom there was no significant difference. Avascular necrosis of the patella was most commonly seen following QT. In both QT &
TTO groups performing a lateral release was significantly associated with AVN of the patella. Extensor lag (>
10°) was seen only in the QT &
TTO groups (11% &
8%) in whom there was no significant difference. Tubercle escape (>
2mm) in the TTO group was significantly greater (54%) in those where circlage wires only had been used than in those where a proximal transfixation wire was used (11%). In conclusion, both QT &
TTO groups had similarly poor knee scores &
ROM pre &
post operation. AVN of the patella for both groups was similar and significantly associated with performing a lateral release. Finally we would conclude that the use of a through wire significantly reduces tubercle escape in TTO fixation.
