Combined Correction of Coronal and Rotational Deformities of the Femur With Distal Femoral Osteotomy Using Patient-Specific Instrumentation

Background: Distal femoral osteotomy (DFO) can be used to simultaneously correct coronal and rotational deformities. Patient-specific instruments (PSIs) are known to be helpful in such complex osteotomies, but data on surgical accuracy for the combined correction of coronal and rotational deformities of the femur are missing. Purpose: To investigate the radiological results of DFO for simultaneous correction of coronal and rotational deformities using PSIs. Study Design: Case series; Level of evidence, 3. Methods: All included patients underwent DFO (34 patients, 36 knees) using PSIs for combined correction of coronal and rotational deformities. The hip-knee-ankle angle (HKA) was measured in weightbearing long-leg radiographs, and the femoral torsion was assessed using computed tomography scans, both pre- and postoperatively. The achieved corrections of HKA and femoral torsion were determined for each knee, and surgical accuracy was calculated. Results: HKA and femoral torsion changed significantly from preoperatively to postoperatively (from 2.4° ± 3.6° vs 0.1° ± 1.8° [ P < .001] and 31.2° ± 17.2° vs 18.7° ± 7.4° [ P < .001]). The difference from planned to achieved correction was statistically greater for HKA (–2.9° ± 3.8° vs –2.3° ± 3.5°; P = .018) than for femoral torsion (–12.4° ± 11.8° vs –12.3° ± 12.2°; P = .771), which did not reach significance. The accuracies of HKA and femoral torsion correction were 1.1° ± 1° and 2.4° ± 1.9°, respectively. Conclusion: Coronal and rotational deformities of the femur can accurately be corrected simultaneously by a DFO, utilizing PSIs. High accuracy was achieved for the correction of both coronal and rotational deformities, with absolute mean differences from planned to achieved correction of 1.1° and 2.4°, respectively.