Midcarpal instability

Midcarpal instability is a collective term for a number of conditions where the instability of the wrist is predominantly between the proximal and distal carpal rows. It has been regarded as relatively rare and infrequently requires surgical treatment. Palmar midcarpal instability is the most commonly found type of midcarpal instability and can be responsible for causing a clunking and painful wrist. The diagnosis is made on clinical grounds using the midcarpal instability provocative tests. Standard imaging and arthroscopic inspection do not usually confirm a definite diagnosis, but are important in excluding other pathologies. The classification and staging has been described using the extent of palmar translocation of the distal carpal row, which is elicited on passive stress tests. As this is a functional instability, it may be that a functional staging description might be better, and a proposed scheme is described. Treatment options including partial wrist fusions, tenodesis stabilizations and arthroscopic capsular shrinkage have been described in small case series with limited follow-up. There are no comparative series or randomized studies because of the relative rarity of this condition.