SCAPHOPISOCAPITATE ALIGNMENT - CRITERION TO ESTABLISH A NEUTRAL LATERAL VIEW OF THE WRIST

PURPOSE: To determine whether a ''true'' neutral lateral view of the w rist is necessary for accurate capitolunate angle measurement, to comp are two standards of diagnostic adequacy for neutral lateral wrist vie ws (distal radioulnar overlap [RUO] and scaphopisocapitate [SPC] relat ionship), and to confirm positional reproducibility and measurement pr ecision of the SPC criterion. MATERIALS AND METHODS: Capitolunate angl es were measured on neutral lateral and supine pisotriquetral views of 10 normal wrists. Two hundred neutral lateral wrist views were classi fied by each standard (RUG and SPC) as excellent, acceptable, or unacc eptable. In two subgroups, capitolunate angles were measured on the la teral views to determine SPC practicality and sensitivity. RESULTS: Co mpared with neutral lateral positioning, supinated off-lateral views s howed an apparent increase in lunate dorsiflexion of up to 30 degrees. Diagnostically unacceptable, excellent, and acceptable pronosupinatio n was present on 118, 22, and 60 of 200 views by using the RUO criteri on and on 40, 79, and 81 of 200 views by using the SPC criterion, resp ectively. The capitolunate angle did not show a significant difference between each of the two subgroups (P > .05). CONCLUSION: A true neutr al lateral view of the wrist is necessary for accurate measurement of the capitolunate angle on the basis of a comparison with off-lateral v iews. SPC relationship provides a diagnostically reproducible standard for a neutral lateral twist view and should reduce the need for repea t lateral radiographs.