Comparison of Mini Tightrope Intermetatarsal Fixation and Inter-Cuneiform Screw Fixation in Lapidus

Abstract

Category: Midfoot/Forefoot; Bunion Introduction/Purpose: First metatarso-cuneiform joint arthrodesis for treatment of metatarsus primus varus was originally introduced by Lapidus in 1934. In his technique, fixation was achieved using heavy chromic sutures between the first and second metatarsals to achieve parallel alignment. Since then, the indications and technique for Lapidus procedure have considerably evolved and many modifications have been introduced to Lapidus’s original description. Despite these modifications, recurrence of hallux valgus remains relatively common, either due to malunion at the TMT arthrodesis or through intercuneiform instability. This has informed the approach for additional fixation between the 1st and 2nd rays. This study aims to compare outcomes of inter-cuneiform screw fixation (ICS) and suspensory intermetatarsal fixation (SIM) using a mini-tightrope in terms of deformity correction and maintaining the correction over time. Methods: This was a retrospective comparative study of prospectively collected data for patients who have underwent a Lapidus procedure for hallux valgus between 2012-2022. The electronic medical records were reviewed for demographics, radiologic parameters, and operative data. Radiographic parameters were intermetatarsal angle (IMA), hallux valgus angle (HVA), and sesamoid station on preoperative, 3 months postoperatively and final follow-up. Hallux valgus station was graded from normal, mild, moderate, and severe based on the method used by Agrawal et al. Using a multivariate regression model, a comparison was conducted between suspensory intermetatarsal fixation(SIM) and inter-cuneiform screw fixation(ICS). Univariate linear regression analysis was conducted with the inclusion of covariates' age, smoking, diabetes, and BMI. Comparison of HVA and IMA was conducted using t-test. Results: 65 patients met the inclusion criteria; 20 had ICS, and 45 had SIM. The pre-op IMA improved from 13.57 (3.84) to 6.14 (2.41) degrees postoperatively in the ICS group (p), and from 13.37(3.84) to 6.16 (2.74) degrees postoperatively in the SIM group (p). The final follow-up IMA was 5.9 (2.1) in the ICS group and 6.84 (2.31) in the SIM group, with no difference from post-op values, p=0.123 and, respectively. There was no statistically significant difference between ICS and SIM groups in IMA at pre-op (p=0.41), post-op (p=0.49), and final follow up (p=0.62). There were no statistically significant differences between SIM and ICS groups in HVA preoperatively [37.47(12.21) vs. 40.38(13.59), p=0.19], postoperatively [18.2(10.82) vs. 18.95(10.1),p=0.36] or at final follow up [20.12(9.72) vs 19.33(9.16) ,p=0.38]. Conclusion: Lapidus procedure remains the procedure of choice for severe hallux valgus with predictable correction. Supplementing the first tarsometatarsal arthrodesis with suspensory intermetatarsal fixation using a mini-tightrope achieved similar deformity correction and preservation of correction to intercuneiform screw fixation.