Patient-Specific Cutting Guides Provide Consistent Planned Correction and Preserved Joint Line Obliquity for Double-Level Knee Osteotomy.

Purpose: This study aimed to evaluate clinical outcomes, accuracy of patient-specific cutting guides (PSCGs) in double-level knee osteotomy (DLO) patients over a minimum 24-month follow-up.

Methods: This single-center retrospective case series included consecutive patients who underwent DLO using PSCGs from December 2016 to May 2022. Inclusion criteria comprised symptomatic knee osteoarthritis with varus/valgus malalignment, planned double-level correction, and a minimum follow-up of 24 months. Primary outcomes were functional improvement (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores) and complications; secondary outcomes included alignment accuracy (hip-knee-ankle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), joint line obliquity (JLO), joint line convergence angle (JLCA)) and patient satisfaction. The WOMAC scores and achievements of minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) were compared between patients with and without postoperative effusion-synovitis. Statistical analysis used the Mann-Whitney U test for alignment accuracy and paired t-tests for functional outcomes.

Results: Among 31 patients (35 knees), the mean follow-up was 36.2 months (range, 24 to 91 months). Patients' average age was 59.3 ± 5.14 years with a BMI of 22.1 ± 1.8 kg/m². HKA improved from 163.9° to 181.1°, MPTA from 83.9° to 91.5°, LDFA from 94.7° to 85.7° and JLCA from 5.6° to 2.4° (all preoperative to postoperative P<0.05). Postoperative values showed no significant difference versus planned values (all P>0.05). Preoperative JLO (4.71°±2.12°) significantly improved to 2.31°±2.02° postoperatively (P=0.019), with no significant difference from the target (2.10°±1.53°, P=0.526). WOMAC total scores decreased from 41.6 to 22.4 (P < 0.001), with 100% achieving the minimal clinically important difference (MCID). Patient acceptable symptom state (PASS) rates varied: WOMAC pain (85.3%), stiffness (67.6%), physical function (94.1%), and total (79.4%). Complications included 2 femoral and 1 tibial hinge fractures, plus 6 venous thromboses (all resolved with rivaroxaban). Patient satisfaction was high (26/31 highly satisfied).

Conclusion: DLO with PSCGs achieved consistent alignment with preoperative plans, preserved physiological joint line orientation, and sustained functional improvements over 36.2 months. All patients met MCID for WOMAC total scores, with 79.4% attaining PASS.