Outcome Study of Highly-cross Linked Polyethylene vs. Standard Polyethylene for Primary Posterior Stabilized (PS) Total Knee

Prospective, Randomized Study of Highly-cross Linked Polyethylene vs. Compression Molded Polyethylene for Primary Posterior-stabilized Total Knee Arthroplasty

Polyethylene wear and osteolysis remain a concern with the use of modular, fixed bearing total knee arthroplasty. A variety of highly cross-linked polyethylenes have been introduced to decrease this problem, but there is little data on the results and complications of this polyethylene in posterior-stabilized knee prosthesis. The investigators asked the following questions: (1) Are there any differences in the clinical and radiographic results when a highly cross-lined polyethylene is compared to a standard liner? (2) What is the frequency of reoperation in these two groups and are there any specific complications related to highly cross-linked polyethylene liners.

This prospective, randomized study will seek to enroll patients undergoing primary total knee arthroplasty. Preoperative evaluation will include a detailed history and physical exam with clinical data collection (SF-36, WOMAC, and Knee Society Scores), a complete description of the procedure, a demonstration of the actual types of implants and tibial inserts, and an outline of the study protocol and informed consent. Intraoperatively, the patient will undergo a total knee arthroplasty utilizing standard operative procedures. Each patient will receive a Zimmer NexGen posterior-stabilized total knee arthroplasty. During the procedure or preoperative visit, the patient will be randomized by sealed envelope to receive either a standard Zimmer UHMWPE tibial insert or a Zimmer highly cross-linked UHMWPE tibial insert. Both surgeon and patient will be blinded to the type of implant used. there will be no variations in surgical technique and hospital management of the patients throughout the course of the study. Postoperatively, the patient will be seen for routine follow-up at six weeks, 6 months, 1 year and yearly thereafter. Radiographs will be obtained at each visit. Clinical data forms will be completed at each visit. At the conclusion of the study radiographs will be assessed for signs of polyethylene wear, osteolysis and component loosening. the preoperative and postoperative knee scores will be calculated for each patient and compared between the patient groups with standard statistical analysis.

Inclusion Criteria:

• all patients indicated for primary total posterior stabilized knee arthroplasty

Exclusion Criteria:

• patients who refused participation
• patients who did not comprehend the English language to give informed consent
• patients with severe knee deformity thought to require a primary constrained condylar prosthesis