Wedge Tarsectomy using Patient Specific Instrumentation in a Tertiary Foot and Ankle Unit

Research Type: Level 4 – Case series Introduction/Purpose: Cavovarus feet can exhibit complex, multiplanar deformities. Commonly used osteotomies fail to address the deformity at the centre of rotation of angulation (CORA). When multiple planes are involved, it can be difficult to perform an accurate single-plane osteotomy which corrects all aspects of the deformity. Weight bearing CT (WBCT) guided wedge tarsectomy with patient-specific instrumentation (PSI) may provide a solution to this challenge. We examine our unit’s results using this technique. Our primary outcome measure was correction of foot position. Secondary outcome measures included patient-reported outcome measures (PROMs), rates of fusion, complications, and reoperation. Methods: This was a single-centre prospective cohort study of patients with cavovarus feet, treated with PSI-guided wedge tarsectomy. Inclusion criteria included adduction deformity that was non-correctable with a soft tissue procedure. Intra-operatively, data was collected regarding the PSI guide accuracy and fixation plan, whether adjustments were required, surgical duration, and the need for adjunctive procedures. All patients undertook pre- and post-operative WBCT, upon which measurements were taken. PROMs data were collected (EQ-VAS and MOxFQ) pre-operatively and post-operatively at 6-month and 1-year follow-up appointments. Statistical analysis was performed using Python (v3.10). Data was continuous and normally distributed. The paired t-test and Pearson test were employed, with a p-value of < 0.05 regarded as significant. Results: Eleven patients were included; all with triplanar cavovarus or skew foot deformities. The CORA was located at the Chopart joint in seven patients, the NCJ in three, and the cuneiforms in one. Mean surgical time was 135 minutes. Accuracy of the PSI guides and fixation plans were rated “excellent” or “good” for all cases. Minor adjustments were required in two cases, adjunctive procedures in nine. Pre- and post-op improvements: Meary’s angle (p=0.039), axial Meary’s angle (p=0.010), talonavicular coverage (p < 0.001) and medial longitudinal forefoot arch (p=0.001). PROMs were available for nine patients. MOxFQ-Walking scores improved with increased correction of adduction (p=0.047, r=0.67). One patient required a calcaneal osteotomy. Two patients had a slight delay in wound healing. One patient suffered neuropathic pain, and one developed CRPS. Conclusion: Wedge tarsectomy with PSI instrumentation is a safe procedure, which provides reliable bony corrections for complex 3D deformities. This procedure reduces operative time, fuses well and provides accurate, predictable corrections, particularly in the axial and coronal planes. Our experience has been favourable, with an excellent experience with PSI cutting jigs. Patients’ experience is similarly favourable, with statistically significantly improved ambulation, particularly in cases with a larger correction. Level of Evidence: Level IV, prospective case series