Purpose: We report a new pathological entity involving the long head of the biceps tendon (LHBT). In this entity, the hypertrophic LHBT becomes incarcerated in the joint during limb elevation, leading to shoulder pain and blockage.

Material and methods: Twenty-one patients were identified. These patients presented hypertrophy of the intra-articular portion of the LHBT with tendon incarceration at limb elevation. The diagnosis was confirmed during open surgery (n=14) or arthroscopy (n=7). All cases were diagnosed in patients with an associated cuff tear. Treatment consisted in resection of the intra-articular portion of the LHBT and appropriate treatment of the cuff.

Results: All patients had anterior shoulder pain and deficient anterior flexion because of the incarcerated tendon. An intra-operative dynamic test consisted in raising the arm with the elbow extended, providing objective proof of the tendon trapped in the articulation in all cases. The positive “hour glass” test produce a fold then incarceration of the tendon between the humeral head and the glenoid cavity. Tendon resection after tenodesis (n=19) or biopolar tenotomy (n=2) yielded immediate recovery of passive complete anterior flexion. The Constant score improved from 38 points preoperatively to 76 points at last follow-up.

Discussion: The “hour glass” long biceps tendon is caused by hypertrophy of the intra-articular portion of the tendon which becomes unable to glide in the bicipital groove during anterior arm flexion. 10°–20° defective motion, pain at the level of the bicipital groove, and images of a hypertrophic tendon are good diagnostic signs. The “hour glass” LGBT must not be confused with retractile capsulitis. The definitive diagnosis is obtained at surgery with the “hour glass” test which shows a fold and incarceration of the tendon during anterior flexion with an extended elbow. Simple tenotomy is insufficient to resolve the blockage. The intra-articular portion of the tendon must be resected after bipolar tenotomy or tenodesis.

Conclusion: Systematic search for “hour glass” LHBT should be undertaken in patients with persistent anterior shoulder pain of unexplained origin associated with deficient anterior arm flexion.