In Situ Subtalar Joint Arthrodesis THE PODIATRY INSTITUTE

In Situ Subtalar Joint Arthrodesis THE PODIATRY INSTITUTE Craig Camasta, DPM; Carl Kihm DPM; Andrea Cass, DPM LITERATURE REVIEW CASE STUDY • Coalition of the subtalar joint middle facet (STJ MF) is associated with the rigid pes planovalgus foot type. 1 • 15 year old female with Patients commonly present with STJ MF coalition between ages of 12 -16 years old. 2 • Typical clinical exam findings: equinus, valgus heel, forefoot pronation, pain, and loss of arch height. 2 • Radiographic findings: blunting of the lateral talar process, talar beaking, halo sign, loss of joint space, and loss of parallelism of the posterior and middle facets on the axial view. 3, • MRIs can confirm radiographic presence of a coalition, give insight 4 to the composition of the coalition, and allow for frontal plane assessment. 3, See Figure 1. • It is not uncommon to identify 4 a STJ MF coalition in a rectus foot type as shown in Figure 1 B. 4 Figure 1 A. STJ MF coalition is common in the rigid pes planovalgus foot type. Here, tarsal wedging is demonstrated. The calcaneus also abuts the fibula. 1 A Figure 1 B. STJ MF coalition can present in patients with a rectus rearfoot. Figure 4 A. Skin incision extends over the floor of the sinus tarsi from the inferior tip of the fibular malleolus to the superior aspect of the calcaneal cuboid joint. The MRI’s axial view demonstrates the frontal plane alignment of the rearfoot. 5 STJ or surrounding joints. STJ arthrodesis is indicated in older patients with arthritis and pain limited to the STJ. • Procedural selection should be chosen on an individual patient basis. • Upon coalition resection, the rearfoot valgus deformity can be corrected via isolated STJ arthrodesis. 7 • Trephine arthrodesis has been described for in situ STJ arthrodesis; 1 of 6 (16. 7%) cases of trephine in situ 8 arthrodesis of the STJ resulted in symptomatic non-union. • Adjunctive procedures may be also indicated to address ankle equinus, pes planovalgus, an unstable medial 9 column, etc. Isolated STJ arthrodesis, double arthrodesis and triple arthrodesis are shown in Figures 2 A-C. 2 A 2 B 3 A 3 B 3 C • Physical Findings: Zero STJ inversion or eversion, rectus rearfoot alignment, medial longitudinal arch intact on stance, ankle dorsiflexion WNL, and inability to perform single limb raise. • Imaging: X-ray findings of the left foot as shown above in Figure 3 A include: halo sign, a visible bridge with inability to identify the STJ MF, blunting of the lateral talar process, and talar neck beaking. Figures 3 B and 3 C show MRI T 1 and T 2 axial images, respectively. On MRI, the STJ MF coalition is visualized and its signal intensity suggests synostosis. The rectus position of the rearfoot is demonstrated on the axial views. • Surgical Plan: Isolated STJ arthrodesis – in situ fusion with maintenance of the osseous STJ MF coalition. 1 B • Surgical procedures generally include STJ MF coalition resection or STJ arthrodesis. • STJ MF resection generally yields better results in younger patients who present without arthritic change of the unremarkable PMH • CC: Left “ankle pain” • HPI: The condition has progressed over several years. The patient can no longer participate in sports due to pain and limitation. De. Kalb Medical 6 2 C Figure 4 B. The STJ is exposed and arthritic loose bodies are removed. The posterior facet surfaces of the STJ are resected of cartilage and subchondral bone. The osseous STJ MF coalition was left intact. 4 A 4 B 4 C 4 D Figure 4 C. The resected joint space is then packed with allogenic cancelllous bone chips. Figure 4 D. Final clinical appearance of the in situ STJ arthrodesis. ANALYSIS & DISCUSSION Gastroc, evans cotton + stj, tn fusion + stj, triple • Glissan’s requirements for successful arthrodesis include: (1)complete extirpation of articular cartilage, fibrous tissues, or other material to expose raw bone surfaces, (2)accurate, close-fitting, position of the opposed joint 1 surfaces, (3)proper positioning of the joint surfaces, (4)undisturbed maintenance until bone healing is complete. 0 • Overall complication rate for isolated STJ arthrodesis has been reported at 37. 5% and 22. 5% of these complications were due to painful internal fixation which required removal. 11 PURPOSE • Demonstrate the surgical technique and effectiveness of this in situ STJ arthrodesis for patients with an osseous STJ MF coalition and rectus rearfoot. • The patient was compliant with non-weightbearing for a 6 week post-operative period. Radiographic fusion was achieved and no complications were encountered. • 5 years post-operatively, the patient continues to function well with an ACFAS rearfoot score of 100. • Glissan’s requirements for arthrodesis were met here without using internal fixation. 5 Stability afforded by the STJ MF coalition maintained the fusion site in good position until bone healing occurred; shown in Figure 5. • By not using internal fixation, cost of surgery can be reduced and the risk of postoperative painful internal fixation requiring removal can be eliminated. • This technique provides a larger fusion area compared that of trephine arthrodesis. • To our knowledge, this is the first demonstration of this in situ STJ arthrodesis technique for treatment of coalitions. Additional outcomes of this technique for patients with an osseous STJ MF coalition and a rectus rearfoot will be presented in the future. 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