Tuberculosis of Shoulder Joint

Tuberculosis of shoulder is rare. It constitutes about 1-2 % of skeletal tuberculosis.[1] It is found more in adults as compared to children. Concomitant lung TB is found more commonly than other skeletal TB.

Relevant Surgical Anatomy of Shoulder Joint

The shoulder joint is a  ball and socket synovial joint. The humeral head is large and glenoid fossa is shallow in comparison.

Glenoid labrum is fibrocartilage ring deepens the joint. The labrum is attached to the margin of glenoid fossa. The capsule of the joint is attached to the scapula beyond the supraglenoid tubercle and the margins of the labrum.

Lower down, the capsule attaches around the articular margins of the head except for inferomedially where its attachment is to the neck of the humerus one cm below the articular margins. This makes part of the proximal humeral metaphysial region intracapsular. The capsule is thick and strong but very lax to permit freedom of movements.

The capsule is reinforced by tendons of subscapularis anteriorly, supraspinatus superiorly, infraspinatus and teres minor posteriorly. These together constitute rotator cuff.  Gaps in the capsule allow communication between the synovial membrane and the subscapularis bursa anteriorly and the infraspinatus bursa posteriorly.

The synovial membrane lines the inner surface of the capsule.

A subacromial (or subdeltoid) bursa lies under the coracoacromial ligament and protects the surfaces during shoulder movements.

The rotator cuff, long head of biceps and long head of triceps add stability to the joint.

Humeral head is about 30 degrees in retroversion. The major movements that occur at the shoulder are

• Flexion-extension
• Abduction-adduction
• Rotations
• Circumduction (the combination of all the above movements).

Glenohumeral and scapulothoracic joints carry synchronous movements to achieve function of the shoulder joint.

Read detailed anatomy of shoulder joint.

Pathophysiology of  Tuberculosis of Shoulder Joint

The focus of infection can originate in the head of the humerus, glenoid of the scapula, or rarely from the synovium. It is extremely uncommon for the disease to present at the stage of synovium.

As the disease progresses, there is a pain in the joint. There is also a limitation of abduction and external rotation.

There is marked wasting of the muscles especially deltoid and supraspinatus.

As the disease progresses, destruction of the upper end of the humerus and glenoid occur. Eventually shoulder joint undergoes fibrous ankylosis.

Three types of tuberculosis of shoulder are known

Dry Form

On is dry atrophic form, also called caries sicca. It is a more common type. It is characterized by the absence of swelling and sinuses.

Exudative Form

Other form presents with swelling and cold abscess. There may be sinus formation or cold abscess along the deltoid region, along with the biceps tendon, or in the supraspinous fossa. It is also called caries exudata.

Mobile Form

This form is recently described by Patel et al [2]. Also called caries mobile, this is characterized by restriction of active movements of the shoulder but passive movements of varying degrees are present, patients having nearly full passive abduction. This happens due to extensive destruction of shoulder joint

Presentation of Shoulder Joint Tuberculosis

Shoulder pain is the most common presentation. By the time patient presents, the disease has already advanced.

Depending on the type of form, there may or may not be swelling present. Restriction of movement is also present. The muscles around the shoulder get wasted.

The patient might have systemic symptoms, though less common, like malaise, loss of appetite, loss of weight and low-grade fever. The shoulder is generally tender on examination. Sinuses and swelling can be seen in some cases.

Diagnostic Work Up

Lab Studies

Following routine lab studies are recommended

• Complete blood count
• Liver function tests
• Renal function test
• Inflammation markers – ESR, CRP

Imaging

Xrays

Anteroposterior and lateral views. Xrays would demonstrate reduced joint space and destruction of the bone of shoulder joint along with generalized rarefaction of bones.

Varying degree of erosion of articular margins or actual destruction of the upper end of the humerus or the glenoid is noticed. In some cases, lytic lesions may be noticed.

In the absence of sinus formation little periosteal reaction is seen. In advanced cases, inferior subluxation of the humeral head may occur.

Three forms of shoulder tuberculosis have different features on x-rays.

The dry form shows narrowing of the shoulder joint and periarticular osteoporosis.

The exudative form shows osteoporosis, erosions of articular surfaces and lytic lesions in the head of the humerus and soft tissue shadow of the cold abscess.

Mobile for shows gross destruction of articular surfaces and a varying amount of destruction of the head of the humerus resulting in widening of articular space.

This table [2] highlights the x-ray and clinical features of different kinds of shoulder tuberculosis

CT/MRI

CT reveals bony details in greater details and can indicate synovial hypertrophy as well.

MRI reveals destructive skeletal lesions, synovial hypertrophy and the presence of fluid reservoirs. It also shows extensive destruction of muscles, stabilizing tendons and capsule of the shoulder joint with humeral bone marrow infiltration.

Biopsy

Whenever there is doubt about the diagnosis the proof should be obtained by subjecting the biopsy of the diseased tissue, to bacteriological and histological examination.

Differential Diagnosis

• Adhesive capsulitis
• Rheumatoid arthritis
• Neuropathic arthropathy
• Villonodular synovitis
• Brucellosis

Treatment of Tuberculosis of Shoulder

Antitubercular therapy consisting of isoniazid, rifampicin, ethambutol, and pyrazinamide is the mainstay of therapy of tuberculosis of shoulder. Additional drugs may be required in some cases.

Classical recommendation is to apply shoulder spica in 70 to 90 degrees abduction, 30 degrees forward flexion and about 30 degrees of internal rotation (saluting position) to encourage ankylosis of glenohumeral articulation in functioning position for 3 months [1] but recent studies have reported good results without use of spica or any other form of splint. [2]

Instead, the authors encouraged early mobilization.

The scapulothoracic articulation of shoulder joint compensates to permit all routine activities even in cases where shoulder ankylosis results

If the patient is not treated, contraction of scapulohumeral muscles pull the humeral head against the glenoid and fix the shoulder in adduction.

Surgery

Arthrodesis is desired where functional movements are not achieved. Arthrodesis can be considered for secondary osteoarthritis. [3] Arthrodesis of the shoulder can be done extraarticular or intraarticular.

Results of tuberculosis range from excellent with a full range of movements to poor which indicates stiff and markedly painful shoulder with the disease still active.

References

1. Tuli SM. Tuberculosis of the Skeletal System. 2nd Edition. Bangalore. Jaypee Brothers. 1997:123-126.
2. Patel P R, Patel D A, Thakker T, Shah K, Shah V B Tuberculosis of shoulder joint. Indian J Orthop 2003; 37: 7-7
3. Antii-Poika I, Vankka E, Santavirta S, Vastamaki M. Two cases of shoulder tuberculosis. Acta Orthop Scand 1991; 62: 81-83.