Patient-specific cutting guides for open-wedge high tibial osteotomy: safety and accuracy analysis of a hundred patients continuous cohort

Introduction Several recent studies have reported accurate and reliable use of patient-specific cutting guides (PSCG) for medial opening-wedge high tibial osteotomy (OW-HTO); however, a majority of these are small cases series or ex-vivo reports. The hypothesis of this study was that performing an OW-HTO with PSCG results in a reliable and accurate correction with good or satisfactory patient-reported functional outcomes at a mean of two years. We also hypothesized that the use of PSCG would not increase the rate of specific or non-specific complications. Methods In this single-centre, observational study, a prospective cohort of a hundred patients (age < 60 years with isolated medial knee osteoarthritis and significant metaphyseal tibial vara) were included between February 2014 and November 2017 to investigate the safety and accuracy of OW-HTO using PSCG. The accuracy of post-operative alignment was defined by the difference between the desired correction defined pre-operatively and the correction obtained post-operatively measured on CT scan (Delta HKA, Delta MPTA, Delta PPTA). Functional outcomes were evaluated by the difference between the value obtained in the pre-operative questionnaire and that obtained at the last follow-up (mean 2 years) using the KOOS and UCLA activity scale. Intra-operative and post-operative complications were recorded. Results The mean patient age was 44.17 +/- 6.77 years; no patient was lost to follow-up at a mean of two years. The mean Delta HKA was 1 +/- 0.95 degrees, the mean Delta MPTA was 0.54 +/- 0.63 degrees, and the mean Delta PPTA was 0.43 +/- 0.8 degrees. No significant differences (all p values > 0.05) were observed between the desired correction defined pre-operatively and the correction obtained post-operatively (Delta HKA, Delta MPTA, Delta PPTA). An improvement of 27 +/- 25 for the KOOS Pain, 28 +/- 26 for the KOOS symptoms, 27 +/- 28 for the KOOS ADL, 26 +/- 33 for the KOOS sport/rec, 28 +/- 38 for the KOOS QOL, and 2.6 +/- 2.4 for the UCLA was obtained as compared with the pre-operative values (all p < 0.0001). No procedures observed were abandoned, and the PSCG was well positioned in all cases. The overall complication rate was 32% up to two years post-operatively, most of them being classed as minor events (28%). Conclusion Performing an OW-HTO with PSCG produces an accurate correction with good functional outcomes at a mean of two years. Furthermore, there is no increase in the rate of specific or non-specific complications. A study to assess the reproducibility of this technique, regardless of the surgical level, is needed.