Anterior Distal Femoral Hemiepiphysiodesis Procedure: A Comparison of Antegrade Versus Retrograde Insertion.

Background: Anterior distal femoral hemiepiphysiodesis (ADFH) is an effective surgery to correct knee flexion contractures. ADFH entails inserting 2 screws through the anterior third of the distal femoral physis, typically inserted in an antegrade fashion (proximal to distal across the physis). However, the screws must traverse significant soft tissue structures, thereby impeding simple insertion parallel to the mechanical axis of the femur. Our surgeons have developed a novel technique using a retrograde approach with a shorter path through soft tissue and an entry point with a broad surface for screw insertion. It is unknown how retrograde ADFH impacts surgical time, clinical outcomes, and complication rates. The purpose was to compare retrograde to antegrade ADFH on surgical times, maximum knee extension angles, and complications.

Methods: Twenty-eight patients (53 knees) who underwent ADFH [12 antegrade (23 knees); 16 retrograde (30 knees)] were retrospectively reviewed. Surgical approach, time, pre and 2-year post-ADFH knee extension angles, and complications were retrieved. The effect of the approach on surgical time was analyzed through an independent t test. The differences between surgical approach on pre-ADFH and post-ADFH knee extension angles were analyzed using a mixed factor RMANOVA. χ 2 performed on complication frequencies. Alpha set to P ≤0.05.

Results: No statistically significant difference was found between surgical insertion and removal times for antegrade ADFH (insertion: 85.2±30.2 min; removal: 118.0±106.0 min) compared with the retrograde ADFH (insertion: 61.7±29.4 min; removal: 56.2±22.8 min). A main effect of time was observed for knee extension angles ( P <0.001). Both groups improved knee extension at 2-year post ADFH (antegrade 5.9±7.3 degrees; retrograde 8.6±8.7 degrees). No differences were found between antegrade and retrograde ADFH on knee extension ( P >0.05). One complication was observed in each approach (retrograde: 1/16 patients, 2/30 knees; antegrade: 1/12 patients, 1/23 knees).

Conclusions: Retrograde had comparable clinical effectiveness and complication rate as antegrade. An advantage of retrograde is the ease of hardware insertion and removal. Combined, these findings suggest retrograde insertion as a viable alternative approach to ADFH.

Level of evidence: Level III.