Disorders of the thumb

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Disorders of the thumb

Disorders affecting the base of the thumb may cause pain over the radial aspect of the wrist. This is why the trapezium–first metacarpal joint and its neighbouring tendinous structures are tested in examination of the wrist.

Disorders of the inert structures

The only relevant passive test for the first carpometacarpal joint is backward movement during extension. Pain and/or limitation indicate a capsular lesion. In the majority of cases, it is the anterior aspect of the capsule that is affected and the joint is found to be tender anteriorly.

The three following conditions are quite common.

Rheumatoid arthritis

Both first carpometacarpal joints are frequently affected in rheumatoid arthritis and respond well to intra-articular triamcinolone. Surgery is seldom necessary but, if so, resection arthroplasty is preferred.¹

Traumatic arthritis

The patient describes an injury to the thumb, usually overstretching. Discomfort and pain are experienced over the thenar area and the radial side of the wrist. The backward movement during extension elicits pain and is limited. The radiograph is negative.¹

Spontaneous recovery may take many months. The condition can be treated either by intra-articular triamcinolone or by 2 weeks’ treatment with deep transverse friction. Friction is given on alternate days and directed to the anterior and anterolateral capsuloligamentous structures.

Arthrosis of the trapeziometacarpal joint, or ‘rhizarthrosis’, is very common. It occurs most frequently in middle-aged or postmenopausal women 2,3 and affects at least 1 in 3 women over 65 and a quarter of men over 75.⁴ Rhizarthrosis is often bilateral and is sometimes found in association with arthrosis at the distal interphalangeal joints of the fingers.⁵ The aetiology is still very unclear. There is evidence that ligament laxity⁶ and trapeziometacarpal subluxation are important early events in the development of thumb arthrosis.⁷

The main symptoms are pain in the dorsoradial and thenar area of the hand and a loss of manual ability and grip strength. In the beginning the pain is cyclic and is felt only during particular activities. As the disease progresses, pain may become constant and may even be present at night. In the final stage, when there is gross joint destruction and subluxation, pain eases but weakness of grip and inability to pinch remain.

Inspection often reveals a dorsoradial prominence of the thumb metacarpal base secondary to subluxation and osteophyte formation. Later on, adduction and Z-deformity of the thumb develop ⁸: the first metacarpal is displaced radially and dorsally and the metacarpophalangeal joint is in a hyperextended position. The thenar muscles are atrophic.

On examination, the combined extension–abduction movement is limited and extremely painful. Crepitus may be felt, especially when the joint is axially compressed and then circumducted – the ‘grind’ test.9,10

The radiographic changes in trapeziometacarpal osteoarthritis are classified into four stages, ranging from mild joint narrowing and subchondral sclerosis to complete joint destruction with cystic changes and bone sclerosis.¹¹ The final stage shows clear signs of sclerosis of the bone, gross osteophytes and a metacarpal that is displaced radially and dorsally. However, care must be taken to base the diagnosis not only on radiographic evidence, but also on symptoms and the physical examination. Most people with radiographic evidence of degeneration of the trapeziometacarpal joint remain asymptomatic and, when questioned, only 28% will admit to pain.¹²

Treatment

The treatment that is chosen depends on the stage of the arthrosis and the functional disability of the joint (Table 24.1). Classically, conservative treatment of osteoarthritis of the trapeziometacarpal joint includes analgesics, joint protection, strengthening exercises of the intrinsic and extrinsic muscles of the thumb, and splints.¹³ Surgical management is recommended to relieve intractable pain.

Table 24.1

Summary of treatment of capsular disorders

Deep friction	Intra-articular injection	Surgery
–	Rheumatoid arthritis	Rheumatoid arthritis
Traumatic arthritis	Traumatic arthritis	–
Early arthrosis	Moderate arthrosis	Severe arthrosis

In early arthrosis, deep transverse friction to the anterior and lateral aspect of the capsule can cause the pain to cease but does not influence mobility.

Later in the course of the condition, intra-articular triamcinolone can be tried. It usually has a temporary result only. An open label trial found that steroids had no benefit on carpometacarpal pain at 26 weeks,¹⁴ while a randomized controlled trial evaluating steroids against placebo injection showed that steroids had no benefit in moderate to severe trapeziometacarpal osteoarthritis at 24 weeks.¹⁵ However, the long-term results of triamcinolone are more effective when a traumatic arthritis has supervened.

During the last few decades, intra-articular injections with hyaluronic acid have been promoted as a valuable alternative to intra-articular injections with steroids.¹⁶ A few open label trials^17,18 found that hyaluronic acid reduced pain and improved grip strength during 6-month follow-up, and two randomized controlled trials stated ‘non-inferiority’ of hyaluronic acid compared with steroids for pain relief at 26 weeks.^19,20

Indications for surgical intervention in trapeziometacarpal arthritis are similar to those for arthroplasty of most joints: persistent pain, decreased function, instability, and failure of conservative management.21,22 Surgical options vary with the stage and nature of the disease. In the early stages, trapeziometacarpal ligament reconstruction and tendon interposition procedures^23–27 have been shown to provide good symptomatic relief. For severe or late-stage disease, some have advocated arthrodesis of the trapeziometacarpal joint, assuming that there is good mobility of the joints proximal and distal.^28–30 Arthroplasty techniques have ranged from simple partial or complete trapeziectomy to various implant and ligament interposition and reconstructions.^31,32 These techniques have been generally indicated for stage II or greater disease once conservative management has failed.

Disorders of the contractile structures

Pain

Resisted extension

This movement seldom causes pain in isolation. Because the extensor brevis and abductor longus tendons lie together in one tendon sheath, in the majority cases resisted abduction is also painful.

Abductor pollicis longus, and extensor pollicis brevis (first tendon sheath)

Intersection syndrome

Intersection syndrome is a specific painful disorder of the forearm that is relatively common but sometimes not correctly diagnosed clinically. It has also been referred to in the literature by the terms ‘peritendinitis crepitans’, ‘oarsmen’s wrist’, ‘crossover syndrome’, ‘subcutaneous perimyositis’, ‘squeaker’s wrist’, ‘bugaboo forearm’ or ‘abductor pollicis longus syndrome’.³⁴ Dobyns et al introduced the term ‘intersection syndrome’, an anatomical designation related to the area in which the musculotendinous junctions of the first extensor compartment tendons (abductor pollicis longus and extensor pollicis brevis tendons) intersect the second extensor compartment tendons (extensor carpi radialis longus and extensor carpi radialis brevis tendons), at an angle of approximately 60° (Fig. 24.3).³⁵

Fig 24.3 Intersection syndrome: the lesions lies at the intersection of compartments one and two, between 4 and 8 cm proximal of Lister’s tubercle.

The most plausible pathophysiology is that of a peritendinitis at the intersection of the two tendinous compartments, which spreads upwards to the musculotendinous junction. The lesion may also lie somewhat more proximally in the muscle bellies; hence the name, ‘myosynovitis’.³⁶ This is shown by magnetic resonance imaging (MRI) findings demonstrating the presence of peritendinous oedema concentrically surrounding the second and the first extensor compartments, beginning at the point of crossover, 4–8 cm proximal to the Lister tubercle and extending proximally.³⁷

The lesion always results from occupational overuse or after unusual effort. It is often associated with sports-related activities, such as rowing,³⁸ canoeing, playing raquet sports, horse riding and skiing.^39,40

The patient mentions crepitus during wrist movements. On examination, resisted extension and resisted abduction of the thumb are painful. Some passive wrist movements can also be painful. This puzzling phenomenon can be explained by the fact that discomfort is increased not only by movements that stretch the tendons (e.g. passive flexion of the thumb and ulnar deviation of the wrist), but also by every movement that pushes the tendon into the tendon sheath (e.g. thumb extension, radial deviation and flexion or extension of the wrist).

On palpation, tenderness and swelling are found in a region about 4–8 cm proximal to the Lister tubercle, where the first and second extensor compartment tendons cross. In cases of recent onset, a silky crepitus during active wrist movements can be palpated.

The differential diagnosis is made from suppurative inflammation of the tendon sheaths, de Quervain’s tenosynovitis (see below), early chronic evolutive polyarthritis, arthrosis of the trapezium–first metacarpal joint of the thumb, lesions of the radial collateral ligament, and tendinosis of the extensor carpi radialis longus and/or brevis.

After an initial stage involving a great deal of pain and disability, the condition may evolve towards a more chronic state. Spontaneous cure may take many months and only occurs when the patient gives the wrist complete rest. Treatment with non-steroidal anti-inflammatory drugs, immobilization and infiltration of steroid or local anaesthetic does not always lead to swift, full and permanent recovery. Deep transverse friction, however (three times a week, over 2 weeks), is extremely successful in this condition, to such a degree that all other treatments must be considered obsolete. This view was confirmed by Paton in 1978,⁴¹ who had used deep transverse friction since 1947 without failure. Bisschop describes 62 cases – 48 men and 14 women – that he treated between 1975 and 1982. The onset was recent (less than 6 weeks) in 55 cases and chronic (2.6 months on average) in 7. Forty-eight of the patients received other treatments, with poor results: steroid infiltration in 16 cases; local anaesthetic infiltration in 4; plaster immobilization in 13 (average 1.8 weeks); partial immobilization with tape in 2; ice friction in 4; physiotherapy in 9. Deep transverse friction – performed three times a week for 15 minutes – led to complete recovery in all but one case, with an average of 6.7 treatments, and 39 patients improved from the first treatment onwards.⁴²

Technique: deep transverse friction

The patient’s forearm rests in pronation on the couch, the hand over its edge. With the contralateral hand the therapist brings the patient’s wrist and thumb into flexion (Fig. 24.4). This stretches the tendons. The other hand takes hold of the patient’s wrist; the thumb then lies flat on the site of the lesion.

Fig 24.4 (a) Friction to the abductor pollicis longus, and extensor pollicis longus and brevis; (b) detail of hand fixation.

Movement starts with the thumb at the ulnar side of the tendons. By supination of the arm, the thumb passes over the tendons to the radial aspect. Repeated movement results in a to-and-fro movement.

Tenovaginitis of the first compartment

This is a lesion of the common tendon sheath of the abductor pollicis longus and extensor pollicis brevis tendons at the wrist. Two conditions can be distinguished – mechanical and rheumatoid – that require the same treatment.

Mechanical tenovaginitis

Fritz de Quervain, a Swiss physician, is given credit for first describing this condition in a report of five cases in 1895.⁴³ The disorder has since been known as de Quervain’s disease, tenovaginitis stenosans or styloiditis radii.⁴⁴ Although the term ‘stenosing tenosynovitis’ is frequently used, the pathophysiology of de Quervain’s disease does not involve inflammation. On histopathological examination, de Quervain’s disease is not characterized by inflammation, but by thickening of the tendon sheath and most notably by the accumulation of mucopolysaccharide, an indicator of myxoid degeneration.⁴⁵ Therefore de Quervain’s disease should be seen as a result of intrinsic, degenerative mechanisms rather than extrinsic, inflammatory ones. The term ‘styloiditis radii’ is also a misnomer as the lesion is not bony or periosteal.

Incidence of de Quervain’s disease has risen considerably in recent decades.⁴⁶ It occurs mostly in women, with an average age of 47, and almost never appears before the age of 30.⁴⁷ A significant association was noted in patients with de Quervain’s disease after pregnancy.⁴⁸ The cause is presumed to be endocrine in origin and similar to the carpal tunnel syndrome described during pregnancy and the lactating postpartum period.⁴⁹

Very often de Quervain’s disease comes on spontaneously, but it can also result from overuse. Swift repeated movement with exertion of considerable strength is a possible cause.⁵⁰

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