Double-level knee osteotomy accurately corrects lower limb deformity and provides satisfactory functional outcomes in bifocal (femur and tibia) valgus malaligned knees

Double-level knee osteotomy (DLO) is a challenging procedure that requires precision in preoperative planning and intraoperative execution to achieve the desired correction. It is indicated in cases of severe varus or valgus deformities where a single-level osteotomy would yield significantly tilted joint line obliquity (JLO). This study aimed to evaluate the effectiveness of DLO in achieving accurate correction without compromising JLO, using patient-specific cutting guides (PSCGs), in cases of bifocal valgus maligned knees.

A single-centre, retrospective analysis of prospectively collected data for a total of 26 patients, who underwent DLO by PSCGs for valgus malaligned knees, between 2015 and 2020. Post-operative alignment was evaluated and the delta for different lower limb0.05, not statistically significant (ns)). All KOOS subs alignment parameters was calculated; the hip-knee-ankle angle (ΔHKA), medial proximal tibial angle (ΔMPTA), and lateral distal femoral angle (ΔLDFA). At the two-year follow-up, changes in the KOOS sub-scores, UCLA scores, lower limb discrepancy (LLD), and mean time to return to work and sport were recorded. All intraoperative and postoperative complications were recorded. The Mann–Whitney U test with a 95% confidence interval (95% CI) was used to evaluate the differences between two variables; one-way ANOVA between more than two variables and the paired Student's t-test was used to estimate the evolution of functional outcomes.

The postoperative mean ΔHKA was 0.9 ± 0.9°, the mean ΔMPTA was 0.7 ± 0.7°, and the mean ΔLDFA was 0.7 ± 0.8° (all values with p > 0.05, not statistically significant (ns)). All KOOS subscore's mean values were improved to an extent two-fold superior to the reported minimal clinically important difference (MCID) (all with p < 0.0001). There was a significant increase in the UCLA score at the final follow-up (5.4 ± 1.5 preoperatively versus 7.7 ± 1.4, p < 0.01). The mean time to return to sport and work was 4.7 ± 1.1 and 4.3 ± 2.1 months, respectively. There was an improvement in Lower-limb discrepancy preoperative (LLD = 1.3 ± 2 cm) to postoperative measures (LLD = 0.3 ± 0.4 cm), ns. Complications were 2 femoral hinge fractures, 2 deep vein thromboses, 1 delayed tibial healing, and 1 hardware removal for hamstring irritation syndrome.

DLO is effective and safe in achieving accurate correction in bifocal valgus malaligned knees with maintained lower limb length and low complication rate with no compromise of JLO.

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