Use of modular metal block augments and medullary stem augments in primary total knee arthroplasty ( 2-year follow-up)

Abstract

Background The success of total knee arthroplasty depends on obtaining and restoring mechanical alignment, maintaining the joint line, balancing ligaments and soft tissue, restoring the function of quadriceps, achieving a stable implant, and reconstructing substantial amounts of bone lost using metal wedges or by stem augmentation. The benefits of modular augments lie in the simplicity of rectifying the bone defect without the additional risks associated with bone grafts. The aim of this study was to present the results obtained from the use of augments in a group of patients with primary osteoarthritis, who had a significant degree of varus deformity, and to show its applicability. Patients and methods Twenty-five patients (average age 69 years) who had a varus alignment of the knee of more than 20π were included in this study. The mean follow-up period was 24 months. All procedures were performed using a standard technique, and a P.F.C. Sigma Knee Replacement was implanted in all cases. Rehabilitation and mobilization began on the first postoperative day assisted by a physical therapist with full weight bearing. Outcomes were evaluated using the American Knee Society Score. Results The mean improvement in the postoperative arc of flexion was 33π. The average Knee Society knee score was 44 points preoperatively and 82 points at the final follow-up. One patient developed peroneal nerve palsy; this patient recovered after 2 months. Conclusion The study concludes that the use of modular metal block augmentation devices for peripheral tibial defects could serve as a simple, rapid, and dependable technique that yields predictable results, and the inclusion of a medullary modular stem in the implant component confers greater stability for the prosthesis. There are no standards for the augmentation in primary total knee arthroplasty, and each case should be dealt with according to the degree of deformity and bony defect intraoperatively.