Single Medial vs 2-Incision Approach for Double Hindfoot Arthrodesis: Is There a Difference in Joint Preparation?

Background: Double hindfoot arthrodesis is a reliable treatment option in lower extremity deformity and arthritis. Single (medial) and 2-incision techniques have been described. The purpose of this study was to evaluate the extent of cartilage debrided in each approach and to evaluate the competency of the deltoid ligament. Methods: Eight matched pairs of cadaveric specimens were acquired. One limb from each pair was randomly assigned to the single medial incision and the other to the 2-incision technique. Stress radiographs were obtained prior to dissection to evaluate for valgus tibiotalar tilt. The talonavicular and subtalar articular surfaces were denuded of cartilage and the joints disarticulated. The percentage of cartilage debrided was determined using ImageJ software. Postoperative tibiotalar tilt was measured with a technique and threshold previously described by our group. The intraclass correlation coefficient was calculated to determine inter- and intraobserver reliability. Results: The single medial incision demonstrated significantly less cartilage denuded than the 2-incision technique at the talar head (61.1% ± 20.4% vs 88.1% ± 6.1%, P <.001), and the posterior facets of the talus (53.5% ± 7.6% vs 73.6% ± 7.0%, P <.001) and calcaneus (55.3% ± 16.5% vs 81.0% ± 7.4%, P =.001). Overall, 75% of specimens that underwent a single medial incision approach demonstrated increased valgus tibiotalar tilt postdissection, whereas none that underwent the 2-incision technique developed increased tibiotalar tilt (P <.01). The average tibiotalar tilt among these specimens was 4.6 ± 1.3 degrees (range 2.5-5.7 degrees). For all measurements, the intraclass correlation coefficient was greater than 0.8. Conclusion: The posterior facet of the subtalar joint and talar head are at risk of subtotal debridement, as well as increased tibiotalar tilt with the single medial incision technique. Adequate debridement may require greater soft tissue dissection, possibly at the expense of medial ankle stability. Level of Evidence: Level III, retrospective cohort study.