Clinical outcomes after using patient specific instrumentation: is it worth the effort? A minimum 5-year retrospective review of 298 PSI knees

Use of patient specific instrumentation (PSI) for performing total knee arthroplasty (TKA) has been shown to improve component positioning but there is dearth of evidence regarding clinical outcomes. The aim of our study was to report patient satisfaction and functional outcome scores of patients who underwent PSI TKAs at minimum 5 year follow up.

This is a retrospective study of a prospectively collected data of patients who underwent PSI TKAs between January 2012 and October 2015 under a single surgeon. Patient Reported Outcome Measures (PROMs), patient satisfaction questionnaires, surgeon directed 3D planning changes and intra-operative changes were collected and analysed.

The cohort included 298 consecutive PSI TKAs performed on 249 patients at a mean age of 71 years (range: 49-93 years). On an average 4 changes were made for each knee during 3D planning compared to preliminary plan. Intra-operative implant size change was required only in 3% (10 knees). The PROM scores were collected at a mean follow-up period of 6.8 years (range: 5.0-8.6 years) for 224 knees. Oxford Knee Score improved from median pre-operative score of 18 (IQR: 13-24) to median post-operative score of 44 (IQR: 40-47) with a median gain of 23 (IQR: 16-30). The median modified Forgotten Joint Score was 87.5 (IQR: 54.4-98.1). For the Beverland questionnaire, 75% (n = 166) reported being "Very Happy" and only 4% (n = 9/222) were 'Never Happy'.

Excellent patient satisfaction and functional scores at mid-term can be achieve d using PSI technique to perform TKA with careful surgeon directed pre-operative planning.