Impact of BMI on Outcomes after First Metatarsophalangeal Joint Arthrodesis

Abstract

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: First metatarsophalangeal joint (MTPJ) arthrodesis is a commonly performed procedure for patients with various disorders of the first ray including hallux rigidus, severe hallux valgus, failed 1st MTPJ replacement, and failed hallux valgus correction. Outcomes are generally favorable and similar outcomes have been shown in the young and elderly. It is well documented that medical comorbidities have deleterious effects on outcomes in foot and ankle surgery. Obesity - in particular - has been broadly studied among the foot and ankle literature and has been associated with increased complications. Presently, there is a paucity of studies examining obesity's effect on outcomes of 1st MTPJ arthrodesis. This study's purpose was to evaluate outcomes following 1st MTPJ arthrodesis in obese vs non-obese patients. Methods: A retrospective cohort study of 94 patients undergoing first MTPJ fusion over the age of 18 with a diagnosis of hallux valgus or hallux rigidus was performed. Surgical and postoperative outcomes, Visual Analog Pain scale (VAS), and Short Form 36 (SF-36) surveys were examined and stratified into 2 patient groups: BMI < 30 and 3 30, with sub-analyses conducted between Obesity class I (30-34.9) and Obesity class II (35-39.9) patients. Continueous, normally distributed data were compared with independent sample t-tests, while comparisons of categorical data were made using chi-squared tests. Alpha and beta were assumed to be 0.05 and 0.8, respectively. Results: Average overall VAS and SF-36 physical component scores improved significantly at 6 months (P< 0.0001, 0.006) and 1- year postoperative visits (P <0.0001, 0.007) following 1st MTP fusion in the cohort as a whole. No differences in VAS or SF-36 scores were found between the obese (BMI > 30) or non-obese cohorts. Amongst BMI classified subgroups, significantly greater changes in preoperative to 6-month and 1-year postoperative VAS pain were observed in the Obesity class I patients vs. Obsesity class II or greater (P=0.043, 0.022). Conclusion: Our study showed first MTPJ fusion reliably improves pain and physical quality-of-life in arthritic obese and non- obese patients without differences in nonunion, complications, or patient-reported measures. Additionally, we observed that obese patients experienced comparable improvements in VAS pain and SF-36 physical function scores as their non-obese peers. Our findings asset that first MTPJ fusion is an effective procedure for correction of MPTJ pathology in the obese.