Double-level osteotomy for varus knees using patient-specific cutting guides allow more accurate correction but similar clinical outcomes as compared to conventional techniques.

Purpose: Patient-specific cutting guides are increasingly used in the field of osteotomies around the knee and can improve the accuracy of planned correction and more specifically in the case of double-level osteotomy (DLO). The purpose of this study was to analyse the accuracy of postoperative coronal alignment after DLO using patient-specific cutting guides techniques (PSI) compared to conventional techniques. The secondary objective was to compare the functional results between the two groups at short-term follow-up.

Hypothesis: The accuracy of global correction (HKA angle) is better with patient-specific cutting guides compared to conventional techniques for double-level osteotomy METHODS: This multicentric comparative retrospective study included 53 patients (mean age: 53.8 ± 5.2 years, male/female: 44/9) who underwent a DLO for knee varus malalignment. The coronal correction accuracy (as expressed by the difference between postoperative angular values and preoperative targeted correction) was compared between techniques using patient-specific cutting guides (PSI group, n = 27) or conventional techniques (n = 26) for the medial proximal tibial angle (MPTA) and the lateral distal femoral angle (LDFA). Postoperatively, the global alignment expressed by the hip-knee-ankle angle and the joint line obliquity were compared between groups. The postoperative functional results for KOOS and UCLA activity scale score were also compared at a mean follow-up of 1.7 years (1.0-3.1 years).

Results: No difference was observed for the postoperative global alignment between the PSI and the conventional groups (Δ = 0.6 °, p = 0.11) neither for the postoperative posterior proximal tibial angle (Δ = 1.6°, p = 0,99) or the joint line obliquity (Δ = 0.3°, p = 0,17). In the coronal plane, the postoperative MPTA was lower in the PSI group (Δ = 2.3°, p < 0.001) as well as the postoperative LDFA (Δ = 0.9°, p = 0.01). Concerning correction accuracy in the coronal plane, the results showed a significant higher accuracy of the planned correction in the PSI group compared to the conventional group for MPTA (2.2 ± 0.2 versus 0.8 ± 0.7, Δ = 1.5 °, p < 0.001) and LDFA (1.3 ± 1.0 versus 0.6 ± 0.9, Δ = 0.7°, p < 0.001). No improvement difference was observed between the conventional group and the PSI group respectively for the KOOS symptoms (p = 0.12), the KOOS Pain (p = 0,57), the KOOS activities of daily living (p = 0.61), the KOOS sport/rec (p = 0.65), or for the KOOS Quality of Life (p = 0.99) neither for the UCLA (p = 0.97).

Conclusions: This study suggests that the use of custom-made cutting guides improves the accuracy of planned correction in double-level osteotomy compared with conventional techniques, which may have implications particularly in centers not performing a large volume of osteotomies. This improved accuracy is not associated with any difference in joint line obliquity or functional results but these results need to be confirmed by a randomized prospective study.

Level of evidence: III; Retrospective comparative study.