Early radiographic accuracy and intra-operative parameters of patient-specific instrumentation versus conventional technique in knee osteotomies for adolescent deformity correction: A prospective comparative study.

BACKGROUND

Patient-specific instrumentation (PSI) has been proposed to improve geometric precision in osteotomy around the knee, but prospective comparative evidence in skeletally maturing adolescents is sparse. We compared the two techniques in this group.

METHODS

In this prospective comparative cohort study, 24 adolescents (15-20 years) with genu varum (n = 10) or genu valgum (n = 14) underwent medial opening-wedge high tibial osteotomy (HTO) for varus or lateral opening-wedge distal femoral osteotomy (DFO) for valgus, allocated to a PSI-assisted (n = 12) or conventional (n = 12) group. The primary outcome was absolute hip-knee-ankle (HKA) angle error at 6 months (success ≤2°). Secondary outcomes were sagittal and joint-line parameters, operative time, fluoroscopy exposure, complications, and International Knee Documentation Committee (IKDC), Lysholm and Visual Analogue Scale (VAS) scores.

RESULTS

PSI achieved a higher success rate (12/12, 100% vs 6/12, 50%; p = 0.0137) and a lower mean HKA error (0.38° ± 0.19° vs 2.06° ± 0.58°; p < 0.0001). In the tibial (HTO) subgroup, posterior tibial slope was preserved with PSI (-0.10° vs +0.72°; p < 0.0001). Joint-line obliquity and convergence angle improved with PSI but deteriorated after conventional surgery (both p < 0.0001). Operative time fell 32.2% (56.1 vs 82.7 min; p < 0.0001) and fluoroscopy 61.1% (35 vs 90 images; p < 0.0001). No PSI case lost correction versus 5/12 (42%) conventional cases (p = 0.0373). At 6 months PSI yielded higher IKDC (84.0 ± 2.62 vs 74.0 ± 3.91; p < 0.0001), Lysholm (92.7 ± 1.50 vs 87.8 ± 5.02; p = 0.0037) and lower VAS pain (0.93 ± 0.20 vs 2.79 ± 1.11; p < 0.0001).

CONCLUSION

In adolescents, PSI-assisted osteotomy around the knee delivered more accurate and reproducible coronal correction, better preservation of sagittal and joint-line geometry, lower operative and radiation burden, no loss of correction, and superior early function. Conventional osteotomy remained effective but less predictable. Higher cost and a planning learning curve are the principal limitations of PSI.