A Prospective Randomized Controlled Trial Comparing Medial-Pivot versus Posterior-Stabilized Total Knee Arthroplasty.

BACKGROUND: The medial-pivot (MP) design for total knee arthroplasty (TKA) aims to restore more natural "ball-and-socket" knee kinematics compared to the traditional posterior-stabilized (PS) implants for TKA. The objective of this study is to determine if there was any difference in functional outcomes between patients undergoing MP-TKA vs PS-TKA. METHODS: This prospective randomized controlled trial consisted of 43 patients undergoing MP-TKA vs 45 patients receiving a single-radius PS-TKA design. The primary outcome was postoperative range of motion (ROM). Secondary outcomes included the Western Ontario and McMaster Universities Arthritis Index, Oxford Knee Score, Knee Society Score (KSS), and radiological outcomes. All study patients were followed-up for 2 years after surgery. RESULTS: Patients undergoing MP-TKA had comparable ROM at 1 year (114.6° ± 16.3° vs 111.3° ± 17.8° respectively, P = .88) and 2 years after surgery (114.9° ± 15.5° vs 114.9° ± 16.4° respectively, P = .92) compared to PS-TKA. There were also no differences in Western Ontario and McMaster Universities Arthritis Index (26.8 ± 19.84 vs 22.0 ± 12.03 respectively, P = .14), Oxford Knee Score (42.7 ± 8.1 vs 42.3 ± 6.7 respectively, P = .18), KSS clinical scores (82.9 ± 16.96 vs 81.42 ± 10.45 respectively, P = .12) and KSS functional scores (76.2 ± 18.81 vs 73.93 ± 8.53 respectively, P = .62) at 2-year follow-up. There was no difference in postoperative limb alignment or complications. CONCLUSION: This study demonstrated excellent results in both the single-radius PS-TKA design and MP-TKA design. No differences were identified at 2-year follow-up with respect to postoperative ROM and patient-reported outcome measures.

Long-Term Results of Revision Total Hip Arthroplasty Using a Modern Extensively Porous-Coated Femoral Stem.

BACKGROUND: The use of an extensively porous-coated uncemented cobalt-chrome monoblock femoral stem for revision total hip arthroplasty (THA) is well established with excellent mid-term results. The aim of this study is to report the long-term survivorship of these implants in femoral stem revisions. METHODS: This is a long-term retrospective review of prospectively collected data of 55 femoral stem revisions in 55 patients using a contemporary, cementless extensively porous-coated cobalt-chrome monoblock stem. All patients between 2001 and 2006 who underwent first time femoral stem revision with a contemporary, cementless extensively porous-coated cobalt-chrome monoblock stem were included. Harris Hip Score, Western Ontario and McMaster Universities Index, and University of California Los Angeles activity scores were recorded preoperatively and at latest follow-up. Radiographs were analyzed for evidence of loosening, subsidence, osteolysis, and bony union. This study included 55 patients, comprising of 36 females (66%) and 19 males (34%) with a mean age of 66.4 ± 9.3 years at the time of surgery. The mean time interval from index procedure was 9.8 ± 2.9 years. Mean time from revision THA to final follow-up was 13.2 ± 2.17 years with a minimum of 10 years of follow-up. RESULTS: Indications for revision included aseptic loosening (33), prosthetic joint infection (13), and periprosthetic fracture (10). Significant improvement in Harris Hip Score (85.1 ± 1.77 vs 51.8 ± 2.3, P < .001), Western Ontario and McMaster Universities Index (17.6 ± 0.77 vs 33.3 ± 0.8, P < .001), and University of California Los Angeles (5.25 ± 0.2 vs 2.7 ± 0.36, P < .001) scores were found at latest follow-up compared to preoperative. Fifty-four patients (98%) achieved stable bony ingrowth on radiographic analysis. All 10 patients treated for periprosthetic fractures achieved bony union of their fractures. Two patients suffered intraoperative periprosthetic fractures and were treated with a cable-plating system. There were no mechanical failures and no femoral stem re-revisions. One patient was diagnosed with a deep infection and was treated with chronic suppressive antibiotic therapy due to significant medical comorbidities. CONCLUSION: Revision of the femoral component with a contemporary extensively porous-coated cobalt-chrome femoral stem has excellent functional outcomes, radiographic outcomes, and long-term survivorship with minimal complications.