Effect of Posterior Osteophytes on Total Knee Arthroplasty Coronal Soft Tissue Balance: Do They Matter?

Abstract

Achieving coronal plane balance in total knee arthroplasty (TKA) is of paramount importance. There is concern that obtaining balancing before removal of posterior osteophytes may lead to asymmetrical extension balance once removed. We hypothesized that there is a particular posterior osteophyte size and location that does not result in significant change in coronal gap balancing. In this study of 245 robotic arm-assisted TKAs, the size and location of posterior osteophytes were obtained from preoperative computer tomography scans. Gap measurements at 10°-25° and 90° flexion after removal of medial and lateral osteophytes, before and after posterior osteophyte removal and bone resection were compared with respect to the size and location of posterior osteophytes. The largest size posterior osteophytes measured >10mm in 8.2% of cases, 5-10mm in 34.7%, <5mm in 23.7%, and 23.7% had no osteophytes. The mean osteophyte size was 5.7mm. The cohorts with and without posterior osteophytes were both found to have significant but similar changes in all gaps after osteophyte removal and bone resection (mean 0.8-1.4mm, P < .0001 and mean 0.7-1.7mm, P < .0001, respectively). Osteophyte size and location had no significant effect on the change in postresection gaps. This included osteophytes greater than 10mm, but their incidence was small. There is a small significant change in gaps between initial assessment and subsequent TKA bone resections, with or without posterior osteophytes. Our study found that where the surgeon thoroughly removes the medial and lateral osteophytes on initial exposure, posterior osteophytes <10mm can be ignored during initial knee coronal balancing.