Does Conventional Radiography Overrepresent Joint Space Narrowing in Hallux Rigidus? A Comparative Study With Weightbearing CT Imaging.

BACKGROUND

Conventional weightbearing radiographs are the gold standard for grading hallux rigidus (HR), yet clinical symptoms often do not correlate with radiographic severity. This study compared 2-dimensional (2D) weightbearing radiographs with weightbearing computed tomography (WBCT) to evaluate if traditional imaging overrepresents joint degeneration.

METHODS

A retrospective study of 21 patients (13 males; average age 55.9 years) with HR was conducted. All patients had both weightbearing radiographs and WBCT. Two fellowship-trained orthopaedic surgeons measured the first metatarsophalangeal joint (first MTPJ) space, dorsal osteophyte height, and dorsal narrowing percentage. Inter-rater reliability was assessed using intraclass correlation coefficients (ICCs).

RESULTS

Joint space width was significantly larger on WBCT (1.9 ± 0.44 mm) compared to radiographs (0.92 ± 0.53 mm; P < .001). WBCT also showed significantly less narrowing of the dorsal articular surface (22.78% ± 8.71% vs 46.57% ± 18.8%, P < .001). Inter-rater reliability for joint space narrowing was excellent for WBCT (ICC = 0.91) but moderate for radiographs (ICC = 0.67; P < .001). WBCT was more sensitive in detecting loose bodies and sesamoid changes.

CONCLUSION

WBCT demonstrated consistently larger joint-space measurements and less dorsal joint-space narrowing compared with conventional radiographs, along with substantially higher inter-rater reliability for joint space narrowing. These findings indicate a systematic measurement difference between modalities, with radiographs tending to overrepresent joint-space loss. This discrepancy may help explain why joint-preserving procedures such as cheilectomy can succeed even when radiographs appear advanced.

LEVEL OF EVIDENCE: Level III, retrospective comparative study.