Spondylometaphyseal dysplasia sutcliffe type (case report)

Spondylometaphyseal dysplasia Sutcliffe type (SMDST) was delineated as a separate entity in 1965 (6). Thereafter, in 1974, a father and his daughter with SMDST were reported as having a variant of spondylometaphyseal dysplasia (1). The fifth patient with SMDST, and the third reported under the accepted designation was not described until 1989 (2). A year later Langer et al (5) reported 7 affected persons and coined the term "SMD corner fracture type”. Two further cases with SMDST, one with severe genu valgus deformity, were reported in 1992 (3). In 1993 Kozlowski et al (4) published three children with SMDST. A forth patient with bilateral coxa vara had rectangular platyspondyly with smooth vertebral plates, which were different from the oval shaped vertebral bodies of SMDST. This individual probably had a variant form of SMDST. The authors stressed that corner fractures are not a unique feature of SMDS but also occur in other complex generalised bone disoders (spondyloepimetaphyseal dysplasias).

This boy was referred to the Departament of Human Genetics in Capc Town at the age of 2 years with bilateral coxa vara which had been detected following disturbance of gait. A cleft lip and palate had been repaired during infancy, but he was otherwise well. Clinically, he was normal, apart from proportionate small stature. Radiographs revealed gross coxa vara with irregularity of the upper metaphyses of the femoral necks. The skull, spine and hands were reported as normal. The parents were nonconsanguinos and the were no affected kin. The child was seen again at the age of 3 years and 3 months. He still had a disturbed gait, but was otherwise well. His length was 84.5 cm (below the 3^rd centile); The upper segment was 48.5 cm, and the lower segment 46 cm. Radiographs showed severe coxa vara and mild dysplasia of the spine. A striking findings was "corner fractures” of the lower medial femoral metaphyses and upper tibial metaphyses (Fig. 1A-C).

SMDST is characterized clinically by short stature and a waddling gait. The diagnostic radiographic findings consists of bilateral coxa vara, minor-moderate spinal changes, progressive metaphyseal dysplasia and corner fractures (1-3, 5, 6). The most important radiographic feature is bilateral severe coxa vara with grossly normal femoral head which are separated from the femoral shaft by a vertical growth plate. In two reported cases hip radiograms performed in the first year of life were described as normal (5). The spinal changes are characterised by preservation of the infantile oval shape of vertebral bodies in the first few years of life. Later, some flattening and anterior wedging of the vertebral bodies is aapparent. Metaphyseal involvement is characterised by corner fractures and irregularity of the metaphyseal plates. Corner fractures present as small triangular bone fragments at the periphery of the metaphyses adjacent to the growth plate and are usually already evident when coxa vara is detected. Metaphyseal irregularity appears later. Both metaphyseal abnormlities progress with age.

What are the minimum criteria for diagnosis of SMDST? Metaphyseal changes of the proximal femoral metaphyses with coxa vara the most important radiographic sing although in one of the cases documented by Langer et al (5) and one of Kozlowski et al (4) only one hip was affected. Corner fractures are the most frequent and evident metaphyseal abnormality. Irregularity of the metaphyses is very variable and in the first few years of life the changes may be minimal. Similarly, spinal involvement may be easily overlooked if not carefully sought. Persistence of the infantile (oval) shape of the vertebral bodies in the first few years of life may precede the irregularity of the vertebal plates and flattening of the vertebal bodies. As few of the patients with congenital coxa vara have long term skeletal survery, the relationship between isolated idiopathic or congenital bilateral coxa vara and SMDST is uncertain. They may represent the spectrum of the same disorder, and it is possible that the molecular investigations will eventually answer this question.

We consider that in every patient with short stature and congenital coxa vara should have full skeletal survey. Review by a specialist-radiologist, medical geneticist or orthopaedic surgeon, who is familiar with variants of paediatric bone radiology is also recommended.

The differential diagnosis of SEMDST is with other bone dysplasias presenting with coxa vara and/or corner fractures (4). In all these disorders the pattern of bony changes including the spine and metaphyseal changes is different and confusion with other conditions is unlikely. Corner fractures are important radiographic sign in battered child syndrome, Menkes kinky hair syndrome and scurvy. However the clinical history, phenotype of pattern of other bony changes is unlikely to cause confusion.