Upsizing the femoral component increases patellofemoral contact force in total knee replacement.
With total knee replacement (TKR), correct sizing and rotational alignment are essential for good clinical outcomes. Overstuffing may result in loss of flexion and adversely affect the outcome of TKR. The purpose of this study was to correlate overstuffing with patient reported clinical outcomes and anterior knee pain (AKP). Baseline and follow-up clinical and radiological data of 262 patients who had NexGen LPS posterior stabilized TKR without patellar resurfacing between 2008 and 2009 were prospectively collected. We measured anterior femoral offset, femoral diameter, and posterior condylar offset on the pre-operative and postoperative lateral non-weight bearing radiographs. Overstuffing was defined as an increase in pre-operative to postoperative values. Repeated measures analysis of variance (ANOVA) was used to analyse for differences from preoperative to postoperative WOMAC scores between patients with and without overstuffing. A total of 193 sets of lateral radiographs (preoperative and postoperative) were adequate for analysis. Anterior overstuffing was noted in 84 patients (43.5 %), posterior overstuffing in 168 (87 %), and total overstuffing in 155 patients (80 %). Total WOMAC scores were similar in patients with and without anterior, posterior or total overstuffing (p = 0.11, p = 0.65, and p = 0.06, respectively). We found no relation between the presence of AKP with either anterior, posterior or total overstuffing (chi-square: p = 0.14, p = 0.24, and p = 0.54, respectively). We found no relation between radiological anteroposterior overstuffing with patient reported outcome measures or AKP.