A normal-looking woman complains that she repeatedly sprains her ankles. Examination reveals that she has marked pes planus and valgus hindfeet (Fig. 42.1). She has extremely flexible fingers, wrists, knees and spine (Fig. 42.2).

1 Diagnose this condition.

2 What heritable disorders of connective tissue should be excluded in your diagnosis?

3 How would you grade the severity of this young woman’s condition?

4 What systemic sequelae are associated with this condition?

5 How should this condition be managed?

6 Specifically with regard to her feet, how should the problem of recurrent sprains be managed?

Fig. 42.1

Standing posterior view showing marked valgus alignment of both heels

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Fig. 42.2

(a) Hyperextension of metacarpal and proximal interphalangeal joints. (b) Wrist hyperflexion. (c) Hyperextension of knees. (d) Increased spinal flexibility

Benign joint hypermobility syndrome

1 Benign joint hypermobility syndrome (BJHS). Patients with BJHS show an increase in joint mobility. Sprains, subluxations and dislocations are common. Other musculoskeletal features include nerve compression disorders and early osteoarthritis.

2 Marfan’s syndrome, Ehlers–Danlos syndrome and osteogenesis imperfecta are genetic diseases that include hypermobility as a feature. The skin hyperelasticity, hernias, lens anomalies and abnormal body proportions that typify these conditions are not present in patients with BJHS.

3 This patient scores 9/9 on the Beighton Scale (Table 42.1).

4 Mitral valve prolapse is more prevalent in patients with BJHS, as are uterine prolapse in women, varicose veins, bruising and generally poor wound healing.

5 Education on joint protection is important in BJHS. Strengthening and proprioceptive exercises are recommended to improve joint muscle function.

6 The tendency to recurrent ankle sprains may be lessened by use of antipronatory in-shoe orthoses. Additional supportive strapping or splinting may be helpful (Fig. 42.3).

Fig. 42.3

Supportive strapping to improve ankle stability

**Table 42.1** Criteria for joint hypermobility: the Beighton Scale (after Beighton et al 1983)
Item	Points
Passive dorsiflexion of little fingers beyond 90°	1 point each hand
Passive apposition of thumbs to flexor aspects of the forearms	1 point each hand
Hyperextension of knees beyond 10°	1 point each knee
Hyperextension of elbows beyond 10°	1 point each elbow
Forward flexion of the trunk, with knees straight, so the palms of hands rest easily on the floor	1 point

Key points

• Patients with BJHS show an increase in joint mobility.

• Marfan’s, Ehlers–Danlos and osteogenesis imperfecta are genetic diseases that include hypermobility as a feature.

• The Beighton Scale is used to grade the severity of this condition.

• Patients with BJHS may have additional health problems.

• Feet are often involved with BJHS and are treated with orthoses and supports.

Diagnosis of rheumatoid arthritis

1 In early presentation of rheumatoid arthritis, the feet are involved more frequently than the hands. Patients often complain of ‘walking on pebbles’. Further examination will reveal swelling and tenderness in the MTP joints. These are painful when squeezed laterally.

2 Joint effusions can lead to spreading of toes, giving rise to the ‘daylight sign’. Inflamed and full bursae are likely to be present over the metatarsal heads on the plantar side.

3 Radiographs of the feet show diagnostic erosions of the fifth metatarsal head. The metatarsal heads are the most common sites of erosive change, with an order of involvement from metatarsal 5, then 3, 2, 4 and 1. The metatarsal head erodes before the base of the proximal phalanx. The distal IP joints are rarely affected.

4 Investigations should include measurement of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), tests for rheumatoid factor and radiographs. Radiographs may be unremarkable in early disease (see also Table 43.1).

5 Disease-modifying antirheumatic drugs should be considered to retard the erosive process. Specific foot therapy is aimed at ensuring the patient’s footwear is adequately wide at the toe box. Cushioning insoles will also help.

**Table 43.1** Laboratory findings in rheumatoid arthritis (based on Akil & Amos 1995)
Laboratory test	Abbreviation	Positive indication for RA	Normal values
Anaemia		(Normochromic or hypochromic, normocytic)
Thrombocytosis
• Serum iron concentration		Low	Male: <65 µg/dl
• Serum iron concentration		Low	Female: <50 µg/dl
• Low total iron binding capacity		Low	250–460 µg/dL
• Serum globulin		Raised
• Serum alkaline phosphatase		Raised
Acute phase response
• Erythrocyte sedimentation rate	ESR	Raised	Male: 1–13 mm/h
• Erythrocyte sedimentation rate	ESR	Raised	Female: 1–20 mm/h
• C-reactive protein concentration	CRP	Raised	<6 mg/l
Rheumatoid factor	RF	Present	Titres >1:80
Antinuclear antibodies	ANA	Present	Titres >1:80

Key points

• Presentation of pain and swelling in the forefoot without a history of trauma should raise the suspicion of rheumatoid disease, particularly if accompanied by joint pain elsewhere.