Comparison of Radiographic and Intraoperative Visual Assessment of Scaphotrapezoid Joint Arthritis in Patients With End-Stage Carpometacarpal Arthritis of the Thumb Base.

Background: The purpose of this investigation is to compare the radiographic and intraoperative assessment of scaphotrapezoid (ST) joint arthritis in patients with end-stage carpometacarpal (CMC) arthritis of the thumb base. We aim to define the incidence of ST arthritis in this population and determine whether radiographic features such as lunate morphology, dorsal intercalated segment instability (DISI), and scapholunate (SL) diastasis are associated with the incidence of ST arthritis.
Methods: We retrospectively reviewed consecutive patients with end-stage CMC arthritis of the thumb treated operatively with trapeziectomy. Preoperative wrist radiographs were reviewed, and the presence of ST arthritis was determined using the Sodha classification. Lunate morphology, DISI, and SL diastasis were noted. Intraoperative grading of ST arthritis was assessed using a modified Brown classification. The specificity and sensitivity of radiographic assessment was compared with the gold standard of intraoperative direct visualization.
Results: In total, 302 thumbs met inclusion criteria. End-stage ST joint arthritis determined by intraoperative visual inspection was noted in 31% of cases. No radiographic or demographic variables were found to be risk factors for ST arthritis. Plain radiographs were 47% sensitive and 94% specific in their ability to detect end-stage ST joint arthritis. Conclusions: We report a 31% incidence of end-stage ST joint arthritis in surgically treated patients with CMC arthritis based on visual inspection which is lower than previous literature. Wrist radiographs demonstrate a 47% sensitivity and 94% specificity in predicting end-stage ST joint arthritis. It is imperative to directly visualize the ST joint after trapeziectomy, as radiographs demonstrate poor sensitivity.