Implant and Limb Alignment Outcomes for Conventional and Navigated Unicompartmental Knee Arthroplasty

Accurate implant positioning and restoration of lower limb alignment are major requirements for successful long-term results in unicompartmental knee arthroplasty (UKA). Alignment accuracy was compared between navigated-UKA (nUKA) and conventional-UKA (cUKA) groups using a retrospective matched case-control study (n=129, 58 nUKA, 71 cUKA). Mechanical axis (MA), hip-knee-ankle angle (HKA degrees), coronal implant alignment, and tibial implant posterior slope were measured. No statistically significant difference was observed when comparing MA. HKA degrees or coronal implant alignment (p>0.05). Statistical significance was seen with tibial component posterior slope (p=0.04, nUKA 4.2 degrees, cUKA 2.9 degrees); and between intra-operative navigationally determined HKA degrees and post-operative whole-leg standing (WLS) film HKA degrees. Navigation does not significantly improve UKA alignment compared to conventional methods. Further studies are needed to justify the use of this technology in UKA. (C) 2013 Elsevier Inc. All rights reserved.