Outcomes after Tibiocalcaneonavicular Ligament Reconstruction in Stage IIB and Stage IV Adult Acquired Flatfoot Deformity

Abstract

Category: Hindfoot; Ankle; Midfoot/Forefoot Introduction/Purpose: The tibiocalcaneonavicular ligament (TCNL) is formed from the confluence of the superficial deltoid ligament and the superomedial spring ligament. In advanced flexible adult acquired flatfoot deformity (AAFD), progressive strain on the TCNL can lead to spring ligament tears, deltoid insufficiency, and eventual medial peritalar instability. Historically, medial peritalar instability was corrected using calcaneal osteotomy in conjunction with isolated spring or deltoid reconstruction. A recent study (Brodell et al.) demonstrated the efficacy of TCNL reconstruction in patients with medial peritalar instability. The purpose of this study is to add to this literature using patient-reported and radiographic outcomes in patients undergoing TCNL reconstruction. Patient-reported outcomes were collected using Patient Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) and Pain Interference (PI) surveys. Methods: Sixteen patients (mean age 50.25 years; 11 female, 5 male) who underwent TCNL reconstruction were prospectively identified. TCNL reconstruction was indicated for stage IIB patients (n=13) with large spring ligament tears (>1.5cm on MRI or intraoperatively) or if osseous correction did not provide adequate talonavicular joint correction. TCNL reconstruction was indicated in stage IV patients (n=3) if deltoid reconstruction required additional medial stabilization. No patients underwent lateral column lengthening osteotomies. PROMIS scores were obtained at baseline and at minimum 12-months follow-up (average 16 months). Surgical success was determined using minimum clinically important differences (MCID), defined as improvement greater than one-half the standard deviation of each pre-operative PROMIS domain (PF: +2.9 and PI: -2.5). Pre- and post-operative radiographic parameters were measured: talonavicular uncoverage angle, talonavicular uncoverage percentage, AP talo-first metatarsal angle, Meary’s angle, and medial cuneiform height (MCH). Correlation coefficients determined the relationship between radiographic parameters and PROMIS scores. Results: PROMIS PF scores improved significantly from 38.1+-5.8 to 44.1+-7.1 (p=0.0087). PROMIS PI scores improved significantly from 62.9+-5.1 to 52.3+-8.9 (p=0.0025). Seventy-nine and 77 percent of patients had successful surgeries, as defined by MCIDs in the PROMIS PF and PI domains, respectively. Talonavicular uncoverage percentage and Meary’s angle improved significantly from 34.4+-13.4 to 26.3+-9.9 percent (p=0.0360) and 19.2+-8.8 to 15.3+-6.2 degrees (p=0.0089), respectively. Talonavicular uncoverage angle improved from 29.3+-9.6 to 23.3+-8.0 degrees (p=0.0562), AP talo-first metatarsal angle improved from 15.2+-10.2 to 10.4+-9.0 degrees (p=0.0555), and MCH improved from 13.5+-6.2 to 15.9+-4.8 millimeters (p=0.1374). Post- operative MCH correlated significantly with post-operative PROMIS PF scores (r=0.5941; p=0.0152). Change in AP talo-first metatarsal angle correlated significantly with change in PROMIS PI scores (r=0.5682; p=0.0427). No other correlations were significant. Conclusion: Patients with stage IIB and stage IV AAFD who undergo TCNL reconstructions have excellent patient-reported and radiographic outcomes. Reconstruction of the medial longitudinal arch, as measured by post-operative MCH, is associated with higher post-operative functionality. Surgical correction of midfoot abduction, as measured by change in the AP talo-first metatarsal angle after surgery, is associated with improvements in pain. In patients with medial peritalar instability, TCNL reconstruction can be a valuable technique to correct the sagittal arch, prevent excessive midfoot abduction, and improve pain and functionality.