Professor H A Bird MD FRCP, Emeritus Professor of Pharmacological Rheumatology, University of Leeds
Although the skin may present major problems in patients with Ehlers-Danlos syndrome (EDS), many symptoms also result from the musculoskeletal system where the joints are hypermobile or hyperlax. This is because the abnormal collagen that contributes to the structure of the skin and blood vessels also contributes to the structure of the joints. These are invariably unstable or 'hyperlax' and, since the last edition of this book was published, there has been increasing realisation of overlap between Ehlers-Danlos syndrome Hypermobile type (formerly EDS111) and the condition Joint Hypermobility syndrome (formerly called 'Benign Joint Familial Hypermobility’). Many clinical features are shared by both conditions and for the hypermobile variant of EDS treatment is largely the same. In the other, less common, encountered forms of EDS the degree of joint hyperlaxity or 'joint hypermobility' may be less severe. In the vascular variant it is sometimes almost absent.
Rheumatologists are also increasingly separating 'joint hypermobility' from 'joint hypermobility syndrome', a further innovation since the last edition of this book was published. In large part this has resulted from the widespread adoption of the Brighton criteria, first proposed in 1998. These incorporate the Beighton 1973 criteria previously used but additionally allow a diagnosis of hypermobility when a small number of joints are extremely hyperlax. Realisation that many patients with hypermobile joints are symptom-free but that in a proportion associated symptoms are often found in parts of the body other than the skin and joints, ultimately largely attributable to the faulty collagen at these sites leading to the more generalised concept of 'joint hypermobility syndrome'. Separate involvement found in each of the different body systems is described in other chapters of the book ‘The Management of Ehlers-Danlos Syndrome Handbook’, available from EDS Support UK.
Patients may find that joints dislocate spontaneously. This most frequently happens at the fingers, elbows, shoulders and patella (kneecap). Only a minority of patients have dislocations of the hips. The joints may dislocate following the most minor of trauma or even in the apparent absence of trauma, for example on rolling over in bed. Reduction is usually easy and often patients learn to reduce the joints themselves. The degree of hyperlaxity and frequency of dislocation usually diminish as the patient gets older though; probably because of circulating maternal hormones, joints may be more susceptible to dislocation during pregnancy.
Repeated minor trauma to unstable joints can cause effusions to form in the joints. Joints are normally lubricated by a small amount of synovial ﬂuid. In an effusion this increases, probably as a protective reaction. As a result the joint may feel tense and become swollen. Spinal abnormalities, including twisting (scoliosis) of the thoracic lumbar, have been described. These tend to be more common in adult patients, suggesting that they arise not from inheritance but from mechanical strains imposed by adult upright stance. There may also be asymmetry of the thorax and depression of the sternum.
Foot problems are common, talipes equinovarus (club foot) being the most frequently seen in about 7% of patients. This may result from an intrauterine malposition in a foetus with lax ligaments. Pes planus (ﬂat feet) occurs and worsens with age as the ligaments that retain the natural arches of the feet stretch in response to the adult bodyweight. Claw toes, hallux valgus (deformity of the big toe) and hard keratomas patches on the sole of the foot are all common. Some patients develop peripheral circulatory phenomena, acrocyanosis or Raynaud's phenomenon, pain from which may appear to come from the joints. Chilblains are common, particularly during childhood and the hands and fingers may undergo extreme colour changes in response to a fall in ambient temperature.
Although some patients may wish to consider surgery (and may be advised to by their attending physicians), it should not be forgotten that surgical procedures are complicated by fragility of the tissues. As a result, stitches are often unsatisfactory and may tear out. Closure of operation sites is difficult and may leave an unsightly scar. Bleeding may be persistent and repair of blood vessels delayed. Post-operative haematoma formation may delay wound healing, sometimes predisposing to an increased frequency of infections.
Orthopaedic procedures to stabilise or improve function at one joint sometimes put unanticipated extra strain on adjacent joints. A surprisingly large number of patients with EDS are disappointed with the results of surgery, which should often only be considered as a last resort. It may be helpful to allow patients considering surgery access to other patients with EDS who have already had surgery to enable them to have first-hand experience of the advantages and disadvantages.
Although most of the increased range of movement in joints in patients with EDS arises from the ﬂoppy collagen that affects the strength and stability of the joint capsule, if minor skeletal abnormalities are also present this may additionally cause ﬂexibility of a joint, particularly where joint sockets, which in normal people might be deep, are shallow in patients with EDS. A third important factor in determining joint stability is joint proprioception. This is the body's ability to subconsciously determine the position of a joint at any one time. Normally, small receptors in the joint capsule relay signals up to the brain so the brain can recognise the position of the joint and direct instructions to the muscles around it accordingly. In a hypermobile patient this function is impaired, probably contributing as much to joint instability as to the actual range of joint movement.
The views expressed are those of the author(s) and should not be construed to represent the opinions or policy of the Ehlers-Danlos Support UK or its Trustees.