[Diagnosis and treatment of the metacarpophalangeal joint locking caused by sesamoid turned-over dislocation of the thumb].

OBJECTIVE:To introduce diagnosis and treatment of the metacarpophalangeal joint (MPJ) locking caused by sesamoid turned-over dislocation of the thumb. METHODS:Five cases with metacarpophalangeal joint locking were involved in the study, male 4 and female 1. The average age was 35 years old(ranging from 18 to 47 years). All the patients received manual reduction under local anaesthesia. But only three were successful, others patients were reduced by operation. Metacarpophalangeal joint locking caused by sesamoid turned-over dislocation with the volar plate and the short flexor muscle of the thumb tendon were reveded. The metacarpophalangeal joint locking was released after reduction of sesamoid turned-over dislocation of the thumb. RESULTS:The mean follow-up time was 15 months (3-34 months). The mean range of MPJ flexion was 45 degrees (35 degrees - 60 degrees). The signs for pain and swelling were released. Satisfactory thumb opposition can be seen. CONCLUSION:It was one of the important reasons of the metacarpophalangeal joint locking caused by sesamoid turned-over dislocation of the thumb.