Introduction: Diminished adult stature is a key feature of Hereditary Multiple Exostoses (HME). Current debate on the pathogenesis of skeletal abnormalities in HME centres on whether there are ‘field-change’ effects which might retard bone-growth, or whether exostoses themselves distort normal bone development locally. The latter theory allows for surgical excision of exostoses to improve prospects for local normal bone development whereas the former does not. No study has previously investigated patterns of height disturbance in HME. Such an analysis in a cohort of children and adults with HME may provide evidence for or against either pathogenesis theory, and throw light on the chance of success of lower limb surgery in improving final height.

Methods: Between 1996 and 2000, 172 individuals from 78 families with HME had clinical measurement of standing height and leg length (anterior superior iliac spine to medial malleolus. 71 were skeletally immature (1st and 2nd decades). Surgical intervention in anatomical areas affecting stature (lower limb, pelvis and spine) were recorded. Centile heights were calculated from Tanner Whitehouse charts.

Results: 25/172 (15%) exhibited severe short stature (< 3rd centile height). Overall, Statural retardation was not apparent up to age 10; thereafter progressive diminution in centile height was recorded (figure 1). Before age 10, 25/37 (68%) were over the 50th centile. Beyond this age, 98/35 (73%) were less than the 50th centile (X2=22.42, p< 0.001). 101 patients who had surgery did not achieve a greater stature than those who had not. In the normal population lower limb contribution to height increases with age, whereas in HME it remains static suggesting that the retardation of stature seen between ages 10 and 20 in HME is mainly due to lower limb, not spinal growth retardation. Leg length discrepancy of > 1% of centile height was seen in 35/167 (21%), encompassing all age groups without significant difference.

Discussion: The pattern of height retardation observed in this study is consistent with a progressive linear disturbance which is not apparent in early childhood, but progresses significantly in the second decade. Overt spinal exostoses are rare; and the spine’s contribution to growth retardation in HME appears be far less than that due to the lower limb. Although the genetics of HME allow for a field-change effect as well as a local osteo-chondroma effect, these results reinforce the possibility that solutions to severe short stature in HME may be achieved through lower limb surgery.