Atypical biceps-related complication of proximal humerus fracture leading to internal shoulder impingement due to tendon stump dislocation

Abstract

Non-displaced proximal humerus fractures are usually managed non-operatively despite of minor malalignment. Biceps tendon rupture due to attrition after malunion is rare around the proximal humerus. Rupture of the long head of biceps (LHB) tendon usually occurs inside the joint close to the origin at the labrum. Treatment is usually non-operative with good outcomes. We report a rare case of a 48-year-old female patient with persistent locking and internal impingement 8 months after a proximal humerus fracture with anterior angulation leading to extra-articular reversed LHB tendon rupture with intra-articular dislocation of the proximal stump. Interposition of the tendon (3.5 cm) between the glenoid and the humeral head was confirmed on MRI arthrogram. Arthroscopic proximal tenotomy and stump removal resulted in immediate relief with improved function (subjective shoulder value 95%; Constant Score: 96). False interpretation of symptoms as posttraumatic stiffness should be avoided by a thorough examination and complementary MRI arthrogram investigation.

Background

Proximal humerus fractures represent about 5.7% of all fractures encountered in adults.¹ The majority can be managed non-operatively.² A small percentage of conservatively treated fractures result in a malunion.³ Minor malunion of the proximal humerus without displacement is usually well tolerated and not well known to cause mechanical tendon attrition and rupture as described after distal radius fractures.^{4 5} Chronic ruptures usually occur inside the joint close to the labrum and are treated non-operatively with good outcomes.^{6 7} We describe a rare case of chronic internal impingement syndrome and locking as a result of proximal humerus fracture malunion with anterior angulation and minimal displacement and subsequent extra-articular “reversed” rupture of the tendon with dislocation of the stump into the posterior part of the glenohumeral joint.

Extra-articular ‘reversed’ tendon rupture in association with anterior fracture angulation of the humerus has not been described and to our knowledge there are no case descriptions of intra-articular interposition of a long stump of the long head of biceps (LHB) tendon. This case is important since minor fracture malunion and chronic biceps tendon ruptures are usually managed non-operatively. However in the post-traumatic setting of persistent locking and catching a high index of suspicion is needed to further investigate the shoulder with an MRI arthrogram to make the additional diagnosis of tendon dislocation and intra-articular interposition.

Case presentation

A 48-year-old right-handed healthy woman with no relevant medical history presented with persistent left shoulder pain during abduction (10/15 at 100°), intermittent mechanical locking with inability to abduct the shoulder beyond 100° and with stagnation of improvements with physiotherapy 8 months after an approximately 45° anterior angulated and posterior tilted proximal humerus fracture treated non-operatively with collar and cuff and orthopaedic sling. The patient did not complain about pain in the arm or biceps muscle. Physical examination revealed a restricted range of movement (ROM) with discomfort and the sensation of mechanical obstruction at 100° of abduction (ROM: 160° flexion; 60° external rotation; internal rotation to T10). There was no clinical evidence of a frozen shoulder. Impingement tests according to Hawkins and Neer were positive. Testing of the rotator cuff and the acromio-clavicular joint were unremarkable. The speed test for the LHB tendon was unremarkable and no Popeye sign was clinically visible associated with the subcutaneous morphology of the patient.

Investigations

Radiographs at 1, 2 and 7 months showed a proximal humerus malunion with minimal displacement, with anterior angulation of approximately 45° and posterior tilt of the humeral head within the acceptable limits for non-operative treatment (figure 1).

Figure 1.

Anteroposterior (A) and lateral (B) radiographs of the left shoulder showing anterior angulation at the biceps groove and no displacement according to Neers criteria.

An MRI arthrogram 8 months after the injury revealed an LHB rupture with intra-articular dislocation of an unusually long proximal biceps tendon stump being dislocated in-between the glenoid and the humeral head (figure 2).

Figure 2.

Axial (A), coronal (B) and sagittal (C) MRI images showing a complete tear of the long head of biceps with intra-articular stump dislocation (arrow) in the posterior joint space.

Differential diagnosis

Prior to the MRI arthrogram investigation relevant differential diagnoses included post-traumatic stiffness and frozen shoulder as well as primary and secondary impingement after fracture malunion and a soft-tissue related pathology (biceps tendon; labrum and superior labrum anterior and posterior, rotator cuff and cartilage).

Since there was stagnation of improvement with physiotherapy, no loss of rotation with the arm at side in neutral position and no radiographic evidence for bony impingement at 90° of abduction the indication for an MRI scan was clearly given.

The final diagnosis of LHB tendon rupture with dislocation of the tendon in the posterior part of the glenohumeral joint was eventually made with an MRI arthrogram (figure 2) and confirmed by arthroscopy (figure 3).

Figure 3.

Arthroscopic view showing the large intra-articular stump (A–C) and associated synovitis (D).

Treatment

The patient underwent arthroscopic biceps tenotomy (senior author) with an arthroscopic radiofrequency device (Vapr, Johnson & Johnson), tendon stump removal and an adjacent partial synovectomy followed by immediate unrestricted physiotherapy.

Outcome and follow-up

Immediate pain relief and no further mechanical obstruction and locking were reported by the patient with 160° of abduction, subjective shoulder value of 95% and a Constant Score of 96 points 2 weeks after surgery. These good clinical results were unchanged and maintained at 3, 6 and 12 months after surgery.

Discussion

This is a first description of pain, locking, catching and internal impingement due to an intra-articular glenohumeral dislocation of a long, proximally attached biceps tendon stump after extra-articular rupture at the level of the bicipital sulcus secondary to an angular deformity and malunion of the proximal humerus. This intra-articular tendon incarceration was associated with adjacent synovitis similar to clinical findings associated with a displaced bucket handle tear in the knee joint.

Subluxation or dislocation of the LHB tendon usually occurs in a medial direction out of the sulcus without complete rupture of the tendon.⁸

Boileau et al have described locking and pain due to tendinopathy of the LHB tendon associated with swelling and a diminished capacity of the tendon to glide through the biceps pulley system.⁹ This condition was termed “hour glass” biceps often resulting in a rupture of the LHB tendon close to the origin at the labrum (short stump) leading to symptom relief in many cases without indication for further treatment.⁷ In our case we found a “reversed” tendon rupture far from the labrum with a long tendon stump leading to stump dislocation into the shoulder joint which has not yet been described.

Guidelines for non-displaced or minimally displaced proximal humerus fractures with minor malunion and for LHB tendon ruptures may direct clinicians towards non-operative treatment. However several authors have mentioned the occurrence of lesions of the LHB associated with proximal humerus fractures in general.^{4 10 11} This case points out the necessity of a high index of suspicion to further investigate non-operatively treated proximal humerus fractures with an MRI arthrogram if symptoms persist and to address biceps tendon pathology operatively if indicated.

Patient’s perspective.

I did not feel any more locking of the shoulder the day after the surgery. I was immediately able to do all the movements of everyday life. I am very happy with the result of the surgery.

Learning points.

• Proximal humerus fracture without displacement can be associated with soft tissue lesions (biceps, labrum/superior labrum anterior and posterior, pulley and rotator cuff).

• A high index of suspicion is necessary to further investigate the painful shoulder.

• Additional investigation of choice is an MRI scan, ideally with contrast.

• Catching and locking due to a ruptured long head of biceps tendon can immediately be relieved with arthroscopic debridement.