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 round the articular margins of the head except 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.

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 stabitity 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 diseases progresses, there is pain in the joint. There is also limitation of abduction and external rotation.

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

As the disease progresses, destruction of 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 more common type. It is characterized by 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 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 most common presentation. By the time patient presents, the disease has already advanced.

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

Patient might have systemic symptoms, though less common, like malaise, loss of appetite, loss of weight and low grade fever. 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 upper end of 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 xrays.

Dry form shows narrowing of shoulder joint and periarticular osteoporosis.

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

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

This table [2] highlights xray 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 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 pyrizinamide is 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 forword 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 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 shoulder can be done extrarticular or intrarticular.

Results of tuberculosis range from excellent with full range of movements to poor which indicates stiff and markedly painful shoulder with 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.