Dynamic swan neck deformity in a patient with Ehlers-Danlos syndrome

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Dynamic swan neck deformity in a patient with Ehlers-Danlos syndrome
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  DYNAMIC SWAN NECK DEFORMITY IN A PATIENT WITH EHLERS-DANLOS SYNDROME A. R. ERiyO(~EN, M. O. YENJDfYNYA, S. YILMAZ and M. R. OZBEK From the Department of Plastic and Reconstructive Surgery, Ankara University School of Medicine, Ankara, Turkey A patient with type I Ehlers-Danlos syndrome with a congenital hand deformity described as a dynamic swan neck deformity is presented and causes of the deformity are discussed. Journal of Hand Surgery British and European Volume, 1997) 22B: 1:128-130 Ehlers-Danlos syndrome (EDS) is a group of inherited collagen disorders characterized by the association of hyperelastic skin, skin haemorrhages, hyperextensibility of joints, cutaneous pseudotumours and fragility, and subcutaneous spherules (Gorlin et al, 1976). Comprehensive surveys have been presented by Beighton et al (1969) and McKusick (1974), and the clinical, biochemical, haematological and chromosomal features of the syndrome have been demonstrated (Beighton et al, 1969; McKusick and Martin, 1975; Prockop et al, 1979). There are at least eight variants of the syndrome. EDS is a familial disorder usually transmitted as an autosomal dominant trait; the clinical stigmata tend to be consistent within any family unit. The severity of the clinical problems manifested in any given case depends on the disorder involved and its genetic penetrance (Beighton et al, 1969; Gorlin et al, 1976). structures of the joint. The patient was also able to demonstrate passive apposition of the thumb to the flexor aspect of the forearm (Fig 4). He was hypermobile according to the Carter-Wilkinson criteria (Carter and Wilkinson, 1964) with a mobility score of 5. Laboratory findings including urinalysis, blood counts, sedimentation rate, and platelet count were normal. Bleeding, clotting and prothrombin times were normal. Chest X-ray and ECG did not show any abnor- mal changes. The diagnosis of EDS type I, the gravis variety, was made. The deformity was classed as a dynamic swan CASE REPORT A 20-year-old man was seen in October 1993 with complaints of skin hyperelasticity, deformity and func- tional problems in both hands. Those symptoms had existed since birth and were aggravated particularly during the school years. The appearance of his hands and the hyperelasticity of his skin caused considerable amusement amongst his school fellows. Additionally, the history revealed prematurity (delivered after a 7-month gestation) and frequent injuries during child- hood. The family history was normal. Physical examination on admission was negative except for the skin and hands. On pinch, the skin felt thin, and was extremely hyperelastic and contractile. The hyperelasticity of the palmar skin and insufficiency in grasping and catching functions were remarkable (Fig 1). There were secondary skin folds and interdigital webbings on the dorsum of the hand and fingers (Fig 2). Examination of the hand during exertion showed hyper- extension of the proximal interphalangeal (PIP) joints and flexion of the distal interphalangeal (DIP)joints in the fingers of both hand (Fig 3). This closely resembled the typical swan neck deformity. Active stability test performed on the PIP joints revealed inadequate func- tional stability. In passive stability testing of both PIP and DIP joints, lateral stress was applied to each col- lateral ligament and in the posteroanterior plane to test palmar support, revealing laxity of the ligamentous Fig 1 Fig 2 Extreme hyperelasticity of palmar skin. Note the poor grasp of the contralateral fingers. Secondary skin folds and interdigital webbing due to hyperel- asticity of the skin. 128  EHLERS-DANLOS SYNDROME 129 Fig 3 Hyperextension of proximal interphalangeal joints and flexion of the distal interphalangeal joints in the fingers during exertion to produce a dynamic swan neck deformity. Fig 4 Passive apposition of thumb to the flexor aspect of the forearm. neck deformity . No surgical intervention was under- taken. We offered the use of a Silver Ring s splint (Silver Ring Splint Co., Charlotterville, USA) for the affected fingers, but the patient found our suggestion impractical and refused it. DISCUSSION Type I EDS, the gravis variety, is manifested by classical symptoms of skin hyperextensibility, joint hypermobil- ity, bruisibility, tissue fragility, and delivery of premature infants secondary to the poor connective tissue and friablity of the fetal membranes, but the basic defect is not known (Bull, 1987; Gorlin et al, 1976). In EDS patients, although there is obvious cutaneous hyperelasticity, many of the physical properties of the skin are normal; the molecular stability of collagen and hydroxyproline content of skin are only slightly decreased. The defect in elasticity does not appear to be in the elastic tissue itself but in the cross-binding of collagen fibrils. However, there is apparently an increased quantity of cutaneous elastin. The main aber- ration noted on microscopic examination is the dis- orderly arrangement of the apparently otherwise normal collagen fibrils, although electronmicroscopically there is no difference between the isolated collagen fibrils and elastin fibers from normal skin and skin of patients with EDS. The tensile strength is markedly reduced from a normal of 200 kg/cm 2 to around 35 kg/cm 2 (Beighton et al, 1969; Jansen, 1955; Prockop et al, 1979). Hypermobility, frequent dislocations, joint effusions and instability, spinal abnormalities, foot deformities and early osteoarthritis are commonly encountered mus- culoskeletal problems (Beighton and Horan, 1969; Gorlin et al, 1976). The characteristic hand deformity is hyperextensibility (double-jointedness) in all joints, but it is particularly common in the metacarpophalan- geal joints, and a weak grip is usual especially in types I, IV, and VII (Beighton and Horan, 1969; Rees et al, 1963). The key to PIP joint stability is the conjoined attach- ment of the paired collateral ligaments and the palmar plate to the middle phalanx. This ligament-box con- figuration produces a three-dimensional stability that strongly resists PIP displacement (Dray and Eaton, 1993). Besides joint stability, stability of palmar skin is critical to hand function (Chase, 1990). Swan neck deformity is classified into one of four types (Feldon et al, 1993), and the deformity in our patient has a resemblance to type 1 swan neck deformity, in which the PIP joint is mobile in all positions. Functional stability determined by active and passive stability tests in our patient demonstrated no dislocations and the deformity resulted from primary ligamentous laxity due to the underlying disease, type I EDS. The deformity in the fingers of both hands srcinated from PIP joint hyperextension, and DIP joint flexion was secondary. Despite hyperextension of the PIP joint and DIP joint flexion, the patient maintained the ability to flex the PIP joint completely. Interestingly, the deformity occurred only during exertion and prevented grasping and catch- ing functions of both hands. Surgical procedures for the treatment of type 1 swan neck deformity include DIP joint fusion, dermadesis, flexor tenodesis of PIP joint, and retinacular ligament reconstruction (Feldon et al, 1993). Due to the potential hazards of surgery and possible complications such as tissue fragility, tendency to bleeding, formation of haematoma, poor wound healing and wound dehiscence in patients with EDS, especially in types I and IV, our conclusion was that surgery was not appropriate for this patient with type I EDS. Furthermore, hyperelasticity of palmar skin causing functional instability of both hands was a very import- ant factor in our final decision. We believe the continuous use of a Silver Ring s splint can be helpful in correcting PIP hyperextension and restoring DIP joint extension while allowing motion.  130 References BEIGHTON P and HORAN F 1969 Orthopaedic aspects of the Ehlers Danlos syndrome. The Journal of Bone and Joint Surgery. 51B: 444-453 BEIGHTON P, PRICE A, LORD J and DICKSON E (1969). Variants of the Ehlers-Danlos syndrome: Clinical, biochemical, haematological, and chro- mosomal features of 100 patients. Annals of the Rheumatic Diseases, 28: 228-245. BULL J C Ehlers Danlos syndrome. In: Stark R B (Ed.): Plastic surgery of the head and neck, New York, Churchill Livingstone, 1987, Vol. 1: 140-157. CARTER C and WILKINSON J (1964). Persistent joint laxity and congenital dislocation of the hip. Journal of Bone and Joint Surgery, 46B: 40 45. CHASE R A. Examination of the hand and relevant anatomy. In: McCarthy J G (Ed.): Plastic surgery. Philadelphia, W B Saunders, 1990, Vol. 7: 4247-4284. DRAY G J and EATON R G. Dislocations and ligament injuries in the digits. In: Green D P (Ed.): Operative hand surgery. New York, Churchill Livingstone, 1993, Vol. 1: 767-798. FELDON P, MILLENDER L H and NALEBUFF E A. Rheumatoid arthritis in the hand and wrist. In: Green D P (Ed.): Operative hand surgery. New York, Churchill Livingstone, 1993, Vol. 2:1587 1690. THE JOURNAL OF HAND SURGERY VOL. 22B No. 1 FEBRUARY 1997 GORLIN R J, PINDBORG J J and COHEN M M. Syndromes of the head and neck. New York, McGraw-Hill, 1976:262 268. JANSEN L H (1955). The structure of the connective tissue, an explanation of the symptoms of the Ehlers Danios syndrome. Dermatologica, 110: 108-119. McKUSICK V A (1974). Multiple forms of the Ehlers Danlos syndrome. Archives of Surgery, 109: 475-484. McKUSICK V A and MARTIN G R (1975). Molecular defects in collagen. Annals of Internal Medicine, 82: 585-586. PROCKOP D J, KIVIRIKKO K I, TUDERMAN L and GUZMAN N A (1979). The biosynthesis of collagen and its disorders. Part II. New England Journal of Medicine, 301: 77-82. REES T D, WOOD-SMITH D and CONVERSE J M 1963. The Ehlers-Danlos syndrome with a report of three cases. Plastic and Reconstruction Surgery, 32: 39-44. Received: 17 January 1996 Accepted after revision: 29 May 1996 Dr Er~6qen, Department of Plastic and Reconstructive Surgery, Ankara University School of Medicine, 06100 Cebeei, Ankara, Turkey. ¬© 1997 The British Society for Surgery of the Hand
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