PSI improves surgical reproducibility in MCW-DFO for valgus knee deformity

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Frontiers in Medicine Published April 16, 2026 Medically reviewed April 25, 2026 DOI ↗ By Dr. Lars van Dijk, PhD · Surgical, Procedural & Diagnostic

Key Takeaway

Consider PSI for improved alignment precision in MCW-DFO, but note preliminary retrospective data.

This retrospective cohort study evaluated 34 patients treated with medial closing wedge distal femoral osteotomy (MCW-DFO) for symptomatic valgus knee deformity, comparing patient-specific instrumentation (PSI) to conventional instrumentation. The primary outcome was surgical reproducibility, measured as the difference between planned and postoperative alignment. In the PSI group (16 patients), the difference was 0.46° for the mechanical femorotibial angle (mFTA) and 0.66° for the mechanical lateral distal femoral angle (mLDFA), whereas the conventional group (implied to be the remainder of 34) had differences exceeding 2° for both measures. No effect sizes, absolute numbers, p-values, or confidence intervals were reported for these comparisons.

Safety and tolerability data, including adverse events, serious adverse events, and discontinuations, were not reported in the study. The research was funded by the Italian National Recovery and Resilience Plan (PNRR), Mission 6—Health, under the PEARL Project (PNRR-MAD-2022-12375978).

Key limitations include the preliminary nature of the outcomes and the retrospective study design, which may introduce biases and limit causal inferences. The sample size was small, with only 16 patients in the PSI group, and follow-up duration was not reported, affecting the assessment of long-term outcomes. In practice, these findings indicate that PSI could be more reliable than traditional instrumentation in adhering to preoperative planning for MCW-DFO, but clinicians should interpret the results cautiously due to the early-stage evidence and methodological constraints.

Study Details

Study typeCohort

EvidenceLevel 3

PublishedApr 2026

View Original Abstract ↓

Introduction and aimMedial closing wedge distal femoral osteotomy (MCW-DFO) is a surgical technique used to treat symptomatic valgus knee deformity. This retrospective study aims to evaluate the reliability of Patient-Specific Instrumentation (PSI) in reproducing preoperative planning and to assess preliminary clinical and radiographic outcomes in patients treated with MCW-DFO using the PSI technique compared to conventional instrumentation. This research was conducted within the framework of the Italian National Recovery and Resilience Plan (PNRR), Mission 6—Health, as part of the PNRR-MAD-2022-12375978—PEARL Project, supporting the development of precision-based surgical strategies to prevent early osteoarthritis progression.Materials and methodsBetween 2012 and 2023, 34 patients underwent MCW-DFO, of whom 16 were treated with NewClip Technics PSI and met the study's inclusion and exclusion criteria. Preoperative planning was performed using TraumaCad® software, identifying preoperative and planned mechanical femorotibial angle (mFTA) and mechanical lateral distal femoral angle (mLDFA) values. Postoperative measurements were obtained to determine the difference between planned and achieved alignment as an index of surgical reproducibility.ResultsThe difference between planned and postoperative values for mFTA and mLDFA angles differed significantly between the two groups. In the PSI group, mean postoperative values differed from planned values by 0.46° for mFTA and 0.66° for mLDFA. In contrast, in the conventional instrumentation group, the difference exceeded 2° for both angles.ConclusionsThe PSI technique proved to be significantly more reliable than traditional instrumentation in adhering to preoperative planning in MCW-DFO. The integration of patient-specific technologies represents a precision-surgery approach consistent with PNRR objectives, potentially improving alignment accuracy and contributing to joint preservation strategies in patients at risk of early osteoarthritis.