Clinical features

The clinical features of camptodactyly are a flexion deformity at the proximal interphalangeal joint (PIPJ). A full range of flexion is usually possible, but full extension may require passive assistance or may be impossible (fixed deformity). Full extension may result in the digit deviating to the ulnar side. The distal interphalangeal joint is rarely involved unless there is a secondary Boutonniere deformity. There may be a preceding history of trauma.

The congenital form of camptodactyly may be noticed during infancy whereas the acquired form is often not appreciated until adolescence when the aberrant musculotendinous structures cannot elongate at the time of rapid growth resulting in a tenodesis effect on the proximal interphalangeal joint. Consequently, the PIPJ flexion deformity progresses with time and can advance to 90 degrees in severe cases. A slow rate of progression or a mild angulation may result in a late presentation for clinical assessment.

Historically, the patient usually presents with a dissatisfaction with the appearance of the hand and the angulation of the involved digits. Usually, they do not complain of pain or discomfort and these symptoms should prompt consideration of alternative causes of PIPJ flexion including arthrogryposis and inflammatory arthropathies.

Examination of the involved digit begins with an assessment of the active and passive range of motion of each joint with a goniometer. Palpation of the contracted PIPJ in full extension is helpful in therapeutic planning. If full passive extension feels springy with the potential for a slight improvement in range with gently increased force, there is a role for stretching and splinting of the joint in the early stages. If the PIPJ feels rigidly fixed on full extension, one must consider a range of causes that are less amenable to conservative measures such as contracture of the flexor tendon sheath, checkrein ligaments, volar plate or bony deformity if longstanding. The same range of motion examinations are carried out with the wrist and metacarpophalangeal joint (MCPJ) in flexion:

• the passive range of PIPJ extension should increase if the cause of the contracture is extrinsic tightness of the flexor tendons
• if no tenodesis occurs during this manoeuvre - the PIPJ failing to extend as the wrist and MCPJ flex - there may be an attenuation of the central slip of the extensor tendon

Compensatory metacarpophalangeal joint hyperextension may be present in longstanding cases of camptodactyly. Passive correction of this posture with the examiner's hand holding the MCPJ in flexion may improve extension at the PIPJ. If this is evident, it indicates that the MCPJ extension may be contributing to abnormal PIPJ flexion.

Given the potential causes, the function of the intrinsic muscles and the long flexors should be checked clinically. Specifically, the flexor digitorum superficialis (FDS) muscle to the little finger should be evaluated by asking the patient to flex the little finger at the PIPJ with the other digits held in extension. If there is no flexion, one cannot assume that there is no FDS to the little finger. A third of patients have a conjoined FDS to the ring finger and therefore, if all digits apart from the ring and little fingers are held in extension and the patient again requested to flex the PIPJ joints, both ring and little fingers will flex if the FDS tendon is conjoined.

A thorough examination must be made for other causes of a flexion contracture of the PIPJ - see main menu of differential diagnoses. A common differential of a flexed ulnar-sided digits is an ulnar nerve lesion and ulnar nerve function should be tested. Equally, the skin should be examined for scarring or a pterygium. Rarely in the typical age groups for camptodactyly, a fascial band may be palpated beneath the skin as a first sign of juvenile fibromatosis.