الفهرس | Only 14 pages are availabe for public view |
Abstract Total hip arthroplasty is the most commonly performed adult reconstructive hip procedure. Total hip arthroplasty evolved as a result of many improvements of designs of femoral head prosthesis, the availability of suitable component materials and manufacturing techniques, a better understanding of hip biomechanics, and the need for resurfacing the acetabulum. Total hip arthroplasty has been associated with excellent implant survival rates, but debate remains concerning the best fixation method for the components. Many studies were done to compare the results of fixation with and without cement and to compare between alternative bearing surfaces. Commonly, cemented hip replacements provide an excellent primary fixation by giving an initial “custom fit” and resistance to axial and torsional stresses, thus allowing early pain-free function. The disadvantages, however, may be considerable in active people; indeed long-term cement fatigue, due to the application of repeated loads during daily activity can drive the stem to failure. Furthermore, in case of failure, the cement may be difficult to remove. Despite being in clinical use for many years, the success of cemented femoral stems is still not completely understood. Many reports have demonstrated good long term results with cemented stems. Therefore it seems justified to still use cemented stems in all age groups of patients. Otherwise, cementless stems have good outcomes in longterm follow-up due to their stable secondary fixation, but they could produce problems in osteoporotic and heavy patients. Summary (decision making) 106 Furthermore, the poor bone quality in addition to sever and continuous loads can lead to early stress shielding and a higher incidence of thigh pain, as well as a decrease in function. Uncemented total hip prostheses are used predominantly in younger patients. In recent years implant design changes have been made to achieve more proximal load transfer into the femur to reduce proximal stress shielding and thus preserve bone stock for potential revision surgery. The short and midterm results for these prostheses are promising. In conclusion, the published evidence suggests that cement fixation remains excellent and even superior to cementless fixation for the general population with respect to femoral stem fixation. The results of cemented cups have been inferior to cementless fixation in most published reports. Cementless fixation in THA, however, has demonstrated continued improvement in durability. Further research and refinement of study & signs are necessary to more accurately demonstrate the relative value of cement or fixation in THA performed in specific subgroups of patients. THA has been well established in long-term studies in older patients as a reliable, reproducible, and durable treatment option for hip arthritis. However, studies in younger patients have traditionally shown less promising results. The higher failure rate of THA in young patients has been attributed to high activity level and excessive demands on the prosthetic hip, along with traditional techniques and cemented components. |