[Editorial] Metal on metal: Is it worth the risk?

There has been an explosion in the use of metal-on-metal bearings in the last 5 years throughout the world. This has mostly been driven by the use of metal bearings in resurfacing, although metal heads have also been used in conjunction with primary total hip arthroplasties. The move to metal heads has primarily been driven by a desire to use larger articulations to reduce dislocations, although smaller metal head combinations are also available and are used clinically. The questions to be addressed in this editorial are firstly to ask if metal bearings do confer a clinical advantage and secondly to look at the potential downside with the use of metal heads

Clinical Outcomes of a Modern Total Knee Arthroplasty Prosthesis Compared to Its Predecessor at 5-Year Follow-Up: Matched Pair Analysis

Background: Residual pain is an important cause of patient dissatisfaction after total knee arthroplasty (TKA). A recent study at our institution found that a modern prosthesis was associated with less residual and anterior knee pain at 2-year follow-up when compared to its predecessor. The aim of this study is to evaluate these implants at 5-year follow-up. Methods: From July 2012 to December 2013, 100 consecutive modern TKAs were identified from our prospective Institutional Review Board approved database. All patients with 5-year clinical follow-up (n = 77) were matched in a one-to-one fashion based on age, gender, body mass index, and follow-up with a predecessor TKA. Clinical outcomes were assessed with a patient-administered questionnaire for specifically anterior knee pain, painless noise, painful crepitation, and satisfaction. Overall function was assessed using Knee Society Scores and Western Ontario and McMaster University Osteoarthritis Index. Results: At 5-year follow-up, there were no significant differences between the modern TKA and a predecessor TKA in the Knee Society pain or function scores (P =.24 and P =.54, respectively). The overall prevalence of residual pain was less with the modern TKA compared to its predecessor (19.5% vs 36.3%; P =.02), but the prevalence of isolated anterior knee pain was similar in both cohorts (11.7% vs 22.1%; P =.09). There was no difference in painless noise (19.5% vs 13.3%; P =.28) or satisfaction scores (7.9 ± 2.4 vs 7.6 ± 2.6; P =.25) between the modern and predecessor cohorts. Conclusion: At 5-year follow-up, we found that both the modern and predecessor prostheses provided excellent clinical outcomes. The modern TKA was associated with less residual pain compared to its predecessor, but we were unable to detect differences in the prevalence of isolated anterior knee pain, painless noise, Knee Society Scores, or radiographic evaluation

Role of Anatomical Patella Replacement on Anterior Knee Pain

Background Anterior knee pain (AKP) remains a complex issue affecting patient satisfaction after total knee arthroplasty. Several radiographic parameters have been shown to be causative factors with various designs. The aim of this study is to evaluate the known radiographic parameters of AKP and clinical outcomes (ie, AKP) in the setting of a modern prosthesis with an anatomic patella button. Methods Between July 2012 and December 2013, 90 total knee arthroplasties received 3 skyline views taken at 30°, 45°, and 60°. A patient-administered questionnaire was administered at 2-year follow-up to assess the incidence of AKP, painless noise, and satisfaction. Radiographs were analyzed for patellofemoral overstuffing, patellar tilt, and patellar displacement, and evaluated the patella resection angle. Results On the patient-administered questionnaire, 10 (11.1%) patients reported AKP of a mild-to-moderate nature. Thirty-one had the best view at 30 Merchant views, 24 had best views at 45, and 35 had best views at 60. We found that patellar resection angle correlated with AKP (odds ratio 1.21, P = .044) and painless noise (odds ratio 1.22, P = .034). Patellar displacement and patellofemoral stuffing did not correlate with AKP or painless noise. No radiographic measurements correlated with changes in Knee Society Score pain or function scores or range of motion. Conclusion We found that a patellar resection angle correlated with the incidence of AKP and painless noise at 2-year follow-up. We failed to find any correlation with patellofemoral overstuffing, patellar displacement, or patellar tilt with clinical outcomes. We recommend the use of 3 Merchant views to fully evaluate the patellofemoral joint

The P.F.C. sigma RP-F TKA designed for improved performance: a matched-pair study

The press fit condylar P.F.C. Sigma RP-F (rotating-platform, high flexion) knee is designed to provide a range of motion (ROM) of 155 degrees without compromising wear, polyethylene contact stresses, patellofemoral tracking, or stability. The first 50 TKA surgeries using the Sigma RP-F knee performed at the author's institution were matched to 50 rotating-platform knees for age, sex, body mass index, preoperative diagnosis, duration of follow-up, and preoperative ROM to determine the effect of design on postoperative ROM. The mean increase in active ROM in the Sigma RP-F group was 17 degrees, compared with 6 degrees in the rotating-platform group (P =.0011). The mean increase in active ROM in patients who had less than 120 degrees of preoperative motion was 27 degrees in the Sigma RP-F group, compared with 16 degrees in the rotating-platform group (P = .006). With the new P.F.C. Sigma RP-F design, greater ROM can be achieved independent of preoperative ROM