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Patient-Specific Cutting Guides Provide Consistent Planned Correction and Preserved Joint Line Obliquity for
Xinlong Ma1, Zhihu Zhao1, Haohao Bai2
1Center for Digital Orthopaedic Technology and Clinical Application, Tianjin Hospital, Tianjin, China.
Purpose:
To evaluate clinical outcomes and 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 24-month follow-up. Primary outcomes were functional improvement (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] scores) and complications; secondary outcomes included alignment accuracy (hip-knee-ankle, medial proximal tibial angle, lateral distal femoral angle, joint line obliquity, joint line convergence angle) 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), there was a mean 36.2-month follow-up (range, 24-91 months). Patients' average age was 59.3 ± 5.14 years with a body mass index of 22.1 ± 1.8. Hip-knee-ankle improved from 163.9° to 181.1°, medial proximal tibial angle from 83.9° to 91.5°, lateral distal femoral angle from 94.7° to 85.7°, and joint line convergence angle from 5.6° to 2.4° (all preoperative to postoperative P < .05). Postoperative values showed no significant difference versus planned values (all P > .05). Preoperative joint line obliquity (4.71° ± 2.12°) significantly improved to 2.31° ± 2.02° postoperatively (P = .019), with no significant difference from the target (2.10° ± 1.53°, P = .526). WOMAC total scores decreased from 41.6 to 22.4 (P < .001), with 100% achieving the MCID. 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).
Conclusions:
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 the MCID for WOMAC total scores, with 94.1% attaining PASS in physical function and 85.3% in pain subdomains at a minimum 24-month follow-up.
Level Of Evidence:
Level IV, retrospective case series.
