Collateral ligament sprains of the metacarpophalangeal joint (MP) of the long fingers are rare and mostly treated conservatively. Clinical examination to diagnose the severity of these injuries is mandatory. The purpose of our study is to report the results of 15 patients treated surgically.

Twenty-three patients, mean age 48, underwent surgery for Stage 3 radial collateral ligament (RCL) injuries of the middle finger (12), the ring finger (4) and the little finger (7). The mean time from trauma to surgery was 53 days. The clinical evaluation consisted of measuring active joint motion, performing laxity tests at 0°, 30° and 90° of MP flexion, testing for laxity and rotation, looking for a spontaneous overlapping finger (or hyperabducted little finger) in relaxed position and measuring the strength (Jamar).

Among the 23 operated patients, RCL lesions were distal in 8 cases, proximal in 9, and mid-substance in 6. There were 2 Stener-like lesions.

Preoperatively, 16 patients presented an overlapping finger over the next one and 7 had spontaneous hyperabduction of the fifth finger.

Mean follow-up of the 15 patients reviewed was 24 months (8–56).

Mean MP flexion-extension range of motion was 86°/11° (71–99/0–29).

Mean MP ulnar laxity of the injured finger was 18°, 14° and 11° respectively at 0°, 30° and 90° and 19°, 16°and 13°on comparison to the same digit on the opposite side.

Mean MP radial laxity of the injured finger was 28°, 22° and 10° respectively at 0°, 30°, 90°, same digit on opposite side was 29°, 21°, 11°.

There were no postoperative overlapped or hyperabducted fingers concerning spontaneous lateral laxity in extension.

The postoperative rotational laxity test showed differences of arc in supination and pronation between operated finger and healthy side of respectively −12% and +8%.

The postoperative results of RCL repair of the MP in the long fingers are good in spite of some residual ligamentous distension, revealed by the laxity tests. The lateral laxity sign as a simple painless clinical sign for diagnosing complete RCL tears requiring surgery needs a validating study in order to spread its use.

IV; retrospective study.