There is current debate concerning the most biomechanically advantageous knee implant systems, and there is also currently great interest in improving patient satisfaction after knee arthroplasty. Additionally, there is no consensus whether a posterior-stabilized (PS) total knee device is superior to a more congruent, cruciate-substituting, medially-stabilized device (MS). This study compared the clinical outcomes of two such devices. The primary hypothesis was that the clinical outcomes, and specifically the patient satisfaction as measured by the Forgotten Joint Score, would be better in the MS group. This prospective, randomized, blinded Level 1 study compared the outcomes of 100 patients who received a Medacta GMK PS device and 101 patients who received a Medacta GMK medially-stabilized Sphere device (Medacta Intl., Lugano, Switzerland). All patients undergoing elective primary total knee arthroplasty were eligible for participation. Institutional Review Board approval and informed consent from participants were obtained. The devices were implanted using an anatomic alignment/calipered- measured resection surgical approach. Clinical and radiographic assessments were performed preoperatively, 6 weeks, 6 months, and annually. Data were compared using T-test with a significance level of 0.05.Introduction
Methods
Mid-flexion stability is believed to be an important factor influencing successful clinical outcomes in total knee arthroplasty. The post of a posterior-stabilizing (PS) knee engages the cam in >60° of flexion, allowing for the possibility of paradoxical mid-flexion instability in less than 60° of flexion. Highly-conforming polyethylene insert designs were introduced as an alternative to PS knees. The cruciate-substituting (CS) knee was designed to provide anteroposterior stability throughout the full range of motion. As part of a prospective, randomized, five-year clinical trial, we performed quantitative stress x-rays on a total of 65 subjects in two groups (CS and PS) who were more than five years postoperative with a well-functioning total knee. Antero-posterior stability of the knee was evaluated using stress radiographs in the lateral position. A 15 kg force was applied anteriorly and posteriorly with the knee in 45° and 90° of flexion. Measurements of anterior and posterior displacement were made by tracing lines along the posterior margin of the tibial component and the posterior edge of the femoral component, which were parallel to the posterior tibial cortex. (Figures 1–4)Introduction
Methods
There is no consensus whether a traditional post and cam-style posterior stabilized (PS) total knee device is superior to a deep-dish, more congruent cruciate-substituting (CS) device. This study compared the clinical and radiographic outcomes of two such devices. The primary hypothesis was that the clinical outcomes would be equivalent and the secondary hypothesis was that there would be measurable differences in the tourniquet time and intraoperative blood loss. This prospective randomized study compared the outcomes of 56 patients who received a Triathlon® PS tibial insert and 55 patients who received a Triathlon® CS lipped tibial insert (Stryker®, Mahwah, NJ, USA). All patients undergoing elective primary total knee arthroplasty were eligible for participation. Institutional Review Board approval and informed consent from participants were obtained. Regular clinical and radiographic assessments were performed preoperatively, 6 weeks, 6 months, and annually. Data were compared using chi-square test and T-test with a significance level of .05.Introduction:
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Significant proximal femoral remodeling occurs after total hip arthroplasty (THA), with regions of bone loss, and regions of hypertrophy. This study compared three implants for changes in femoral bone mineral density over 2 years following primary uncemented hip arthroplasty with a conventional stem (THA), a novel femoral neck-sparing short hip stem (NS-THA), and resurfacing hip arthroplasty (RHA). Seventy-one patients participated in this non-randomized, prospective study. All patients had a diagnosis of osteoarthritis and underwent primary uncemented hip arthroplasty. Dual Energy XRay Absorptomitry (DXA) scans were performed at preoperative, 3–7 days post-op, 6 weeks, 6 months, one, and two years post-op. Using custom 2 cm zones, 19 zones were observed for percent changes in bone mineral density (BMD). Radiographs and Harris Hip scores were obtained at each visit.Introduction:
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