Alvand A et al. – This prospective randomized controlled trial compared the accuracy of implantation and functional outcome of mobile–bearing medial unicompartmental knee arthroplasty (UKA), implanted with or without patient–specific instrumentation (PSI). Despite comparable improvement of PSI in the Oxford Knee Score (OKS) at 12 months, conventional instrumentation would be preferred until further improvements in PSI guides are demonstrated.

Methods

• Either conventional instrumentation or PSI guides were used to implant mobile–bearing medial UKAs in 43 patients.
• Component positioning was analyzed using postoperative radiographic examination, intraoperative measurements, and size of the implanted meniscal bearing.
• Functional outcome was measured using OKS scale.

Results

• Owing to concerns regarding accuracy and registration on native anatomy mainly on the tibial side, PSI guides could not be used in 3 cases.
• Overall, similar component alignment and positioning were attained with the 2 systems (nonsignificant for coronal/sagittal alignment and tibial coverage).
• Significantly greater tibial slope was demonstrated by the PSI group.
• Higher number of optimum–size meniscal insertions was evidenced in the control group.