A holder for standardized radiological detection of ulnar capsule-ligament lesions of the thumb base joint

AIM OF THE STUDY: To evaluate the usefulness of a self-constructed holding device for standardized, investigator-independent radiodiagnostics for ulnar capsulo-ligamentous lesions of the thumb metacarpophalangeal joint compared to the uninjured side. MATERIAL AND METHODS: A holding device for stress roentgenograms was constructed. Normal abduction arcs were evaluated in 20 degrees flexion in 28 healthy volunteers. The investigator-dependent variance was assessed. The study group comprised 123 consecutive patients (68 male, 55 female, aged 7 to 68 years, mean age 30 years). RESULTS: The normal arc of abduction was calculated to be 12 degrees (range 3 degrees to 24 degrees), while the mean individual difference in side by side comparison in volunteers was 0.3 degree (SD 2.69 degrees, range 0 degree-8 degrees). A rupture was diagnosed in 47 patients; 41 were operated. The preoperative diagnoses confirmed correct in all operated patients. A difference of greater than 6 degrees is indicative of a rupture with a sensitivity of 66.7% and a specificity of 96.9%. CONCLUSIONS: In summary, the holding device is useful for the practical work. Individual differences of less than 4 degrees are negative, between 4 degrees and 7 degrees questionable positive, between 7 degrees and 12 degrees are positive and over 12 degrees proof indicator of a rupture of the ulnar collateral ligament of the thumb metacarpophalangeal joint.