Basal thumb metacarpal osteotomy for trapeziometacarpal osteoarthritis

Journal of Orthopaedic Surgery, Apr 2006 by Gwynne-Jones, D P, Penny, I D, Sewell, S A, Hughes, T H

ABSTRACT

Purpose. To review the subjective and functional results of basal thumb metacarpal osteotomy for the treatment of trapeziometacarpal osteoarthritis.

Methods. Between July 1993 and November 1998, 35 thumb osteotomies without internal fixation were performed on 33 patients in the Christchurch Hospital, New Zealand. Records of 28 thumbs (13 right and 15 left) of 26 patients (17 women and 9 men) were available for review. Patients were reviewed using strength testing and the Michigan Hand Outcomes Questionnaire.

Results. The mean age of the 26 patients was 54 years (range, 30-69 years). Of the 28 thumbs, 22 (21 patients) had good or excellent results, 2 fair, one poor. The remaining 3 thumbs (3 patients) required further revision and were classified as failures. The mean follow-up period of the 25 thumbs (24 patients) not requiring revision was 34 months (range, 12-73 months). Good thumb motion was present in all hands with no trapeziometacarpal instability seen. Compared with the normative data, the strengths of key pinch, pulp pinch, and tripod pinch of our patients were significantly lower (22-32% lower), but not the grip strength. Michigan Hand Outcomes Questionnaire scores increased 28 (range, 1-56) points after surgery, with significant improvement especially in pain ( 44 points), activities of daily living (one-handed tasks, 41 points), and satisfaction ( 35 points).

Conclusion. Basal thumb metacarpal osteotomy is a straightforward, conservative procedure that should be considered for grades II and III trapeziometacarpal osteoarthritis.

Key words: metacarpus; osteoarthritis; osteotomy; thumb

INTRODUCTION

Trapeziometacarpal arthritis is a relatively common condition affecting mainly middle-age or older age-groups. Symptoms involve pain and difficulties in performing work and activities of daily living (ADL), and adduction contracture of the thumb mctacarpal in advanced stage. Many treatment procedures have been described, including simple trapezium excision,1 trapeziometacarpal arthrodesis,2 silicone interposition,3 and replacement arthroplasty.4 Stabilised resection arthroplasty is the current trend, with several variations described.5-9

Basal thumb metacarpal osteotomy has been performed rarely since the work of Wilson.10,11 It is a straightforward and relatively conservative procedure that does not compromise subsequent procedures should revision be required. It avoids the potential complications of instability and weakness after trapezial excision,12,13 and problems of stiffness and nonunion after carpometacarpal arthrodesis.14,15 Good results have been reported in both mild and moderate stages in the longer term.16 A biomechanical cadaver study suggested that the osteotomy may unload the palmar contact areas of the joint in early stage but had no effect in more advanced stage.17

This study aimed to review the subjective and functional results of basal thumb metacarpal osteotomy.

MATERIALS AND METHODS

Between July 1993 and November 1998,35 basal thumb metacarpal osteotomies were performed on 33 patients in the Christchurch Hospital, New Zealand. Indications for surgery were disabling pain and difficulties in performing ADL. All patients had failed non-operative treatment, including at least one intra-articular steroid injection. It is our practice to perform metacarpal osteotomy for younger or high-demand patients with trapeziometacarpal arthritis, when the joint remains mobile. Contra-indications to osteotomy included fixed deformity of the carpometacarpal joint, scaphotrapezial disease, and metacarpophalangeal joint disease of the thumb. Interposition arthroplasty is reserved for older patients with an immobile trapeziometacarpal joint or with a degenerative scaphotrapezial joint.

Preoperative radiographs were independently assessed by a musculoskeletal radiologist and a consultant orthopaedic surgeon according to the classification of Eaton et al18-stage I indicates no cartilage degeneration and normal articular contours; stage II indicates joint-space narrowing with osteophytes less than 2 mm in size; stage III indicates significant destruction of the joint and osteophytes greater than 2 mm in size; stage IV indicates scaphotrapezial degeneration in addition to trapeziometacarpal joint involvement.

The operative technique was the same as that described by Wilson and Bossley11 without internal fixation. A V-shaped incision was made over the dorsoradial aspect of the basal thumb articulation. Terminal branches of the superficial radial nerve were carefully protected. The proximal metaphysis of the metacarpal was exposed and the periosteum reflected. A 25-gauge needle was used to localise the joint. A closing wedge was cut with the base of about 4 mm directed dorsally and radially at the junction of the shaft and metaphysis. The osteotomy was performed with a small power saw and was completed with a fine osteotome. Care was taken not to penetrate the far cortex. The osteotomy site was closed with an absorbable suture through the capsule and periosteum. Supplementary fixation with a Kirschner wire could be used if the osteotomy was mobile, but was not required in any patients in this series. A plaster was applied with the thumb in the corrected position and retained for 6 weeks. Mobilisation under the supervision of a hand therapist was started afterwards. Postoperative radiographs were not routinely performed unless symptoms persisted.