A radiological technique for measurement of the height of the trapezial cavity: Applications in pre- and post-operative assessment in osteoarthritis of the base of the thumb

Abstract

The authors present an original radiological technique which allows a precise measurement of the height of the trapezial cavity. The measurement is performed on an antero-posterior radiological projection of the trapezio-metacarpal joint in a neutral position, as described by Kapandji. The first point of reference is fixed and consists of a line projected through the radial articular surface of the second metacarpal with the trapezium. Two perpendicular lines to this first point of reference, are then projected respectively from the distal extremity of the scaphoid and the base of the first metacarpal, so defining a space which corresponds to the height of the trapezial cavity. We have used this measurement for assessment of the column of the thumb, in a series of 33 patients operated on for trapezio-metacarpal osteoarthritis (18 patients were treated by trapezectomy, ligamentous stabilisation and tendon interposition following Burton's or Jones technique and 15 patients underwent insertion of a Swanson trapezium implant. Radiologic measurement pre- and post-operatively provided information relative to the change of the height of the trapezial cavity after the two different surgical techniques, and to assess the kinetics of collapse of the trapezial gap following trapezectomy.