[Interrater Reliability of Scapholunate Advanced Collapse (SLAC) Wrist Stage Classification and Influence of Diagnostic Wrist Arthroscopy]

Therapy of scapholunate advanced collapse (SLAC) wrist should be guided by the degree of arthritic changes within the radioscaphoid and midcarpal joints (stage 1-3 after Watson). Diagnostic investigations usually include X-ray imaging and wrist arthoscopy. In the present study, the interrater reliability of SLAC wrist stage classification by means of X-ray image analysis was evaluated between radiologists and hand surgeons. Ultimately, the influence of diagnostic wrist arthroscopy on the final stage classification was determined.

Retrospectively, 38 SLAC wrists of 37 patients were included in this study. Conventional X-ray images in a dorso-palmar and lateral view were performed before diagnostic wrist arthroscopy. The degree of carpal collapse on X-rays was determined by 2 radiologists and 2 surgeons (1 board certified hand surgeon, 1 plastic surgeon, both experienced in hand surgery since years). After 14 days the stages were re-evaluated by the surgeons with the digital images from the wrist arthroscopies at hand.

While the interrater reliability turned out to be 'weak' amidst the radiologists, it was classified as 'light' among the surgeons. We found a 'weak' and a 'light' interrater reliability between the surgeons and the radiologists. Radiologists tended to assess the degree of severity higher than surgeons. The additional knowledge of the digital arthroscopy images led to a different classification in 55%. When X-rays were assessed in combination with the arthroscopy findings, both stage 1 and stage 3 were diagnosed less frequently.

Our study suggests that interpreting X-ray films alone is an unreliable method to assess the stage of SLAC wrist. We believe that additional diagnostic measures such as wrist arthroscopy are needed to accurately diagnose the SLAC wrist stage.