A newly developed patient-specific instrumentation system achieves consistent alignment accuracy in varising knee osteotomy.

Abstract

Patient-specific instrumentation (PSI) has been introduced to improve the accuracy of varising knee osteotomy. This study aimed to evaluate the correction accuracy of a newly developed PSI system for varising knee osteotomy, including medial closing-wedge distal femoral osteotomy (MCWDFO), lateral opening-wedge distal femoral osteotomy (LOWDFO), and medial closing-wedge high tibial osteotomy (MCWHTO). Twenty-three patients with valgus knee alignment who underwent varus osteotomy using the new PSI system were retrospectively analysed (MCWDFO, n = 10; LOWDFO, n = 7; MCWHTO, n = 6). The overall error was defined as the difference between the planned and achieved hip-knee-ankle angles (HKAs) at 6 months postoperatively (ΔHKA), reflecting the accuracy of overall lower limb alignment correction. Positive values indicated overcorrection, and negative values indicated undercorrection. Across all procedures, the mean planned and achieved HKA were 178.9° ± 0.7° and 179.3° ± 0.7°, respectively, resulting in a mean overall error of -0.4° ± 1.7° (range, -4.5° to 2.5°). The mean overall error was -1.0° ± 1.7° for MCWDFO, -0.5° ± 1.6° for LOWDFO, and 0.6° ± 1.1° for MCWHTO, with no significant difference among techniques (P > 0.05). No major complications, including hinge fracture or delayed union, were observed. The newly developed PSI workflow achieved high correction accuracy and demonstrated consistent performance across various femoral and tibial osteotomy techniques for valgus correction. These findings indicate that the system provides a reliable and safe approach for achieving precise alignment correction in varus knee surgery.