Quadriceps performance following total knee arthroplasty (TKA) is a critical factor in patient satisfaction that can be significantly affected by implant design (Greene, 2008). The objective of this study was to compare quadriceps efficiency (QE) following TKA with a medial-pivot system (EVOLUTION®, MicroPort Orthopedics Inc., Arlington, TN, USA) to non-implanted control measurements. Five cadaveric leg specimens with no prior surgeries, deformities, or disease were obtained. Each was placed in a custom closed chain device and loaded to simulate a heel-up squat from full-extension to deep flexion (approximately 115°) and back to full extension. Quadriceps force (FQ) and ground reaction force (FZ) were measured, and the ratio of the two was calculated as the quadriceps load factor (QLF). QFLs are inversely related to QE, with higher QFLs representing reduced efficiency. Each specimen was then implanted with a medial-pivot implant by a board certified orthopedic surgeon and force measurements were repeated. Mean pre- (represents control values) and post-implantation QFLs were compared to determine any differences in QE throughout the range of motion.Introduction
Methods
This single centre study was a prospective analysis from 2000 to 2008, aiming to explore and characterise the incidence and management of orthopaedic injuries sustained from motorcycle-related accidents in children under 16 years of age in Far North Queensland. In addition, it aimed to recognise factors contributing to crash occurrence, injury pattern and severity. Prospective survey data has been collected for the past eight years looking at various aspects of non-fatal motorcycle injuries in children up to the age of 16 years who present to Cairns Base Hospital. The study incorporated a simple 12-point questionnaire that was completed upon the child's first presentation to the hospital in either an in- or out-patient clinical setting. The aspects addressed by the survey included: number of accidents, use of safety gear, experience level, injury and management, and cause of the accident. Little research has been conducted on characterising the nature and occurrence of off-road motorcycle accidents in children and adolescents. A total of 238 children were admitted to Cairns Base Hospital with injuries related to motorcycle accidents. The results of 210 children who sustained orthopaedic injuries are presented. Motorcycle accidents involving children were responsible for over 340 presentations to the Emergency department and for a total of more than 500 hospital bed-days upon admission. The majority of accidents occurred off-road with over 40% on public property. An average of 11% of riders was female. This study gives evidence that off-road motorcycle accidents in children are the result of inexperience, utilise a significant proportion of our orthopaedic resources, and that programs and policies directed at reducing the number of injuries from off-road motorcycle riding need implementation.
Ten cases are described of catastrophic failure of the polyethylene liner of three different designs of uncemented acetabular component. Failure occurred as a result of either 'wearthrough' to the metal backing, liner fracture or a combination of both, at a mean of 4.6 years after implantation (2 to 7.6). At revision there was metallosis in all hips and osteolysis of the femur or the pelvis in six. Catastrophic failure was seen only in cups with a minimum polyethylene thickness of less than 5 mm.
