SLR - November 2023 - Khan
Title: Comparison of different surgical treatments for stage II progressive collapsing foot deformity: a finite element analysisReference: Chen F, Yuan C, Liang M, Le G, Xu J. Comparison of different surgical treatments for stage II progressive collapsing foot deformity: a finite element analysis. J Orthop Surg Res. 2023;18(1):719. Published 2023 Sep 23. doi:10.1186/s13018-023-04216-3
Level of Evidence: Level III
Scientific Literature Review
Reviewed By: Maazullah Khan
Residency Program: East Liverpool City Hospital- East Liverpool, Ohio
Podiatric Relevance: Stage II progressive collapsing foot deformity (PCFD) poses a challenge to the podiatric surgeon due to the progressive nature of the deformity and the variety of options to address the deformity. The authors of this paper aim to study various methods of surgical fixation and their biomechanical effects on the medial column. They theorize that medial column osteotomy (MCO) and subtalar joint arthroeries (SJA) could be helpful in shifting pressure from the medial plantar side to the lateral and that lateral column lengthening (LCL) or medial column fusion (MCF) would not be suitable for stage IIA PCFD from a biomechanical perspective.
Methods: A 32 year old 175 cm, 60 kg male with no history of ankle or foot fractures or tumors was used to model simulations. MCF involved a fusion of the navicular and cuneiform bones. MCO involved a 1cm medializing osteotomy of the calcaneus that extends approximately 1-1.5cm behind the posterior edge of the talus to the distal calcaneus at an angle of 45° to the plantar plane of the foot. LCL was done by a transverse osteotomy 10-15mm away from the calcaneocuboid joint, also known as an Evans osteotomy. This osteotomy was fixed with a 1cm thick bone graft. SJA involved implantation of an appropriate arthroereisis model based on the size of the tarsal sinus tarsi, into the subtalar joint.
The study assessed the maximum von-mises values in the medial and lateral columns as well as at distribution of maximal stress on the plantar surface, strain experienced by the medial ligaments and plantar fascia. Arch height, talo-first metatarsal angle, calcaneal pitch, and talar coverage were also assessed.
Results: Mises stress values increased for MCF and LCL while the values decreased with MCO and SJA. Maximum plantar stress increased after MCF and LCL but decreased with MCO and SJA. Regarding stress on the medial ligaments and plantar fascia, MCF had no significant effect while MCO, SJA, and LCL all reduced stress with LCL having the most noticeable change. Radiographically all four procedures corrected talo-first metatarsal angle, calcaneal pitch, and talonavicular coverage. Although MCF was able to obtain radiographic correction, it was not as effective as the other methods, with SJA being the most effective.
Conclusions: The authors conclude that for stage IIA PCFD a Type II sinus tarsi implant effectively transferred pressure from the medial plantar tract to the lateral side and restored the arch. They also concluded that isolated LCL is unsuitable for stage IIA PCFT as it increased adduction of the forefoot and maximum stress on the medial plantar foot. While the authors came this conclusion, this study had multiple limitations, most notably that the sample size is small due to only a single patient being used in the simulation. Another notable limitation in this study is that the simulation uses the same elastic modulus for both cortical and trabecular bones which is significantly different (14,000 vs 350MPa). Lastly, a medial column fusion often includes the 1st tarsometatarsal joint, which is not included in this procedure.