Morphology of the First Tarsometatarsal Joint and the Incidence of Arthritis and Post-operative Complications.

Introduction The first tarsometatarsal joint (TMTJ) is often overlooked regarding foot pathology or a secondary measure in most studies, despite its heavy involvement in surgical procedures and foot stability. The primary aim of this study is to assess the effect of the first TMTJ morphology on the incidence of arthritis and post-operative complications following a Lapidus procedure. Materials and methods A total of 39 feet/subjects (19 left and 20 right) were assessed by two independent reviewers. The first TMTJ angle and articulating surface shape were measured, and relevant descriptive data was compiled. Statistical analysis was used to analyse variable outcomes via a logistical regression model and inter-rater reliability tests to determine the validity of the methods used.  Results A statistically significant relationship between first TMTJ angle and incidence of arthritis was revealed but not with articulating surface shape, or between either measure of first​​​​​​​ TMTJ morphology and post-operative complications. Inter-rater reliability tests showed a very strong correlation between inter-rater measurements.  Discussion The smaller the angle of the first​​​​​​​ TMTJ, the increased incidence of arthritis; therefore, it may be an early sign for clinicians to look for and implement prophylactic interventions sooner. Furthermore, it also signifies that conducting corrective surgeries at this joint will likely have a positive effect on decreasing arthritis pathology. The strong inter-rater reliability findings offer validity to the methods used in this study however can be improved using expert radiographers and AI software.  Conclusion The first​​​​​​​ TMTJ angle and shape of the articulating surface are both valuable predictors of the incidence of arthritis; however, this study cannot claim that they are good predictors for post-surgical complications. Further research is needed to address the limitations found in this study however it is a valuable initial step in identifying foot pathology early and initiating early management.