Clinical Outcomes and Accuracy of Patient-Specific Instrumentation for Corrective High Tibial and Distal Femoral Osteotomy

Background: High tibial osteotomies (HTOs) and distal femoral osteotomies (DFOs) may be used for a variety of knee pathologies including unicompartmental cartilage disorders and ligamentous instability. A novel instrumentation system for osteotomies utilizing 3-dimensional patient-specific instrumentation (3D PSI) cutting guides has been recently described; however, there is limited reporting on the clinical outcomes and accuracy of this system. Purpose/Hypothesis: The purpose of this study was to evaluate the clinical outcomes and accuracy of correction of a 3D PSI osteotomy system. It was hypothesized that patients would have significant improvements in patient-reported outcome (PRO) scores and that ≥90% of patients would have coronal and sagittal alignment within 10% and 3°, respectively, of the planned correction. Study Design: Case series; Level of evidence, 4. Methods: Patients who underwent opening wedge (oW) or closing wedge (cW) HTO or DFO utilizing a 3D PSI system from October 2020 to June 2022 were reviewed. Mechanical medial tibial width ratio (mMTWr) and posterior tibial slope (PTS) were evaluated pre- and postoperatively on full-length standing alignment films and lateral radiographs of the knee, respectively. The absolute difference between the planned correction and postoperative measurements was calculated. PROs (International Knee Documentation Committee [IKDC]; Lysholm; and Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] Pain, WOMAC Stiffness, WOMAC Physical Function, and WOMAC Total) were obtained from all patients at a minimum of 2 years postoperatively. All data are reported as means unless otherwise noted. Results: A total of 23 cases (16 oW HTO, 4 oW DFO, 2 cW DFO, and 1 combined cW HTO + oW DFO) were included at a mean follow-up of 2.6 years. Using a Bonferroni-corrected P value (P < .006), there were significant improvements from pre- to postoperatively in IKDC, Lysholm, WOMAC Pain, WOMAC Stiffness, WOMAC Physical Function, and WOMAC Total scores. Of the 16 cases with full-length limb-alignment films postoperatively, 88% of patients were within 10% of the planned final mMTWr, and the median difference between the planned and actual correction was 3.7% (25%-75%; IQR, 1.7-9.0). Of patients who underwent HTO, 67% were within 3° of the planned final PTS and the mean difference between the planned and actual PTS was 2.2°± 2.0°. Conclusion: This study found that patients who underwent corrective HTO or DFO using 3D PSI had significant improvements in PROs; there was good accuracy of coronal correction with 88% of patients falling within 10% of the planned final mMTWr and moderate accuracy with 67% of patients falling within 3° of the planned final PTS. These findings demonstrate that osteotomy utilizing 3D PSI can lead to clinically meaningful improvements in patient function with high accuracy of planned correction.