Revision TKA using CCK prosthesis showed comparable outcome to PS prosthesis in clinical and radiological results. In revision total knee arthroplasty (TKA), the goal should be to obtain good motion, function and most importantly stability. The stability depends on remaining soft tissue and implant design. The more the ligaments retain function, the less the implant constraint is needed to achieve stability. With increased constraint, the transfer of joint reaction forces to implant-bone interface may lead to mechanical loosening of the implant. Constrained condylar knee (CCK) prosthesis provides more constraint compared with posterior stabilized (PS) prosthesis. The purpose of this study was to compare the clinical, radiological outcome and survivorship of CCK and PS prosthesis in revision TKA.Summary
Introduction
UC TKA showed similar anteroposterior translation and more femoral external rotation of earlier onset when compared to PS TKA. Recently highly conforming ultracongruent TKA has been reintroduced with improved wear characteristics and lower complications. The purpose of the study was to assess kinematics and clinical outcome of posterior stabilized and ultracongruent rotating-platform mobile bearing TKA.Summary
Introduction
To evaluate the clinical and radiologic midterm results of rotational acetabular osteotomy (RAO) in incongruent hip joints. A consecutive series of 15 hips in 14 patients who underwent RAO in incongruent hip joint were evaluated at an average follow-up of 52.3 months (range from 36 to 101 months). The average age at operation was 27 years (range from 12 to 38 years) old. The preoperative diagnoses were developmental dysplasia in 4 hips, sequelae of Legg-Calvé-Perthes disease in 8 hips, and multiple epiphyseal dysplasia in 3 hips. The RAO procedures were combined with a femoral valgus oseotomy in 10 hips, advance osteotomy of greater trochanter in 4 hips, derotational osteotomy in 2 hips. Clinically, Harris hip score, range of motion, leg length discrepancy(LLD) and hip joint pain were evaluated. Radiological changes of anterior and lateral center-edge(CE) angle, acetabular roof angle, acetabular head index(AHI), ratio of body weight moment arm to abductor moment arm, and a progression of osteoarthritis were analyzed.Purpose
Material and Methods
The generation of particle debris from ultra high molecular weight polyethylene (UHMWPE) against metal hip joints has been shown to cause osteolysis leading to joint loosening in the medium term. This is known as late aseptic loosening since infection is absent In an attempt to reduce the volume of wear debris, attention has moved to metal-on-metal prostheses as the total volume of wear debris is less. However, the size, shape and number of the particles are important as well as the total volume as these affect the biological response of the body leading to aseptic loosening. The Durham Mk I Hip Joint Simulator was used to generate CoCrMo wear particles in a series of tests. Four simulator tests took place in succession, initially 50 mm Birmingham hip replacements were tested where both the head and the cup were as-cast CoCrMo alloy. A second test was conducted where the components were 38 mm and both head and cup were as-cast CoCrMo. A third test using 50 mm components was completed where both head and cup were double heat treated CoCrMo alloy and a final test took place where both components were 50 mm the head was as-cast and the cup was as-cast which had been pre-worn to 5 million cycles. Bovine serum with a concentration of 17 g/l of protein was used as a lubricant and particles were sampled every half million cycles. The volumetric wear was also obtained gravimetrically. A double enzymatic protocol was used to cleave the proteins from the particles taking great care to minimise any effect on the particles. Finally the particles were suspended in distilled, de-ionised water to enable them to be analysed using a NanoSight LM10 particle analyser. This yielded the size distribution of the particles. This was then confirmed by placing an aliquot of the suspended particles onto a carbon coated copper grid and drying them under a lamp. These particles were then imaged in the TEM. Energy Dispersive X-ray analysis was also used to obtain the chemical composition of the particles. The results indicated a strong correlation between the gravimetric wear and the number of particles. All the as-cast CoCrMo alloy tests showed a consistent particle modal average size. The double heat treated particles were shown to be smaller, with occasional large flake like particulates which were identified under the TEM. This particle data correlates extremely well with previous data from simple material testing pin on plate experiments. Previous studies have used microscopy to investigate the size and morphology of the particulate debris
