The Diagnostic Utility of Lateral Thumb Radiographs in Detecting Thumb Carpometacarpal Arthritis

Thumb carpometacarpal (CMC) arthritis is commonly evaluated using radiographs to guide treatment decisions. No consensus exists on optimal radiographic views or interpretation methods. The purpose of this study was to determine whether lateral thumb radiographs demonstrate more advanced degenerative changes than Bett's anteroposterior (AP) and oblique views in patients with thumb carpometacarpal arthritis.

We retrospectively reviewed preoperative Bett's AP, oblique, and lateral radiographs from consecutive patients undergoing thumb CMC arthroplasty (June 2023 to March 2025). Two reviewers independently evaluated radiographs using the Osteoarthritis Research Society International atlas, grading joint space narrowing (JSN) and osteophyte severity (both on 0-3 scales) and recording presence/absence of joint subluxation, erosions, subchondral sclerosis, and cysts. Each reviewer scored radiographs twice with minimum 1-week interval. Statistical analysis employed nonparametric tests for ordinal severity scores and matched-pair analysis for binary outcomes. Cohen's kappa assessed inter- and intra-rater reliability.

Twenty-five patients (38 radiograph sets) were included (mean age 61 years; 52% women). Lateral views demonstrated considerably higher JSN scores and more frequent detection of erosions, cysts, and subluxation compared with AP and oblique views. Lateral views demonstrated considerably higher intra- and inter-rater reliability for erosions; however, higher κ values for osteophytes, JSN, subluxation, sclerosis, and cysts did not reach statistical significance.

Lateral thumb radiographs demonstrated more advanced degenerative changes, particularly joint space narrowing, erosions, cysts, and subluxation, compared with standard AP and oblique views in thumb CMC arthritis evaluation.

Diagnostic IV.