Aim: This study presents analysis of the largest case series to date in the published literature of patients with Hurler Syndrome, to identify the severity of thoraco-lumbar kyphosis, risk factors for progression and results of intervention.

Methods and Results: Forty two patients with MPS-I had treatment with Bone-marrow transplantation and/ or enzyme replacement therapy between June 1995 and October 2007. These patients had regular systematic clinical review and were seen at least annually. Standing lateral radiographs of the thoracolumbar spine were retrieved and analysed.

At initial examination (average age 1y 1m) the thoracolumbar kyphosis measured a mean of 39.6 degrees (SD 12 degrees). Analysis of non-operatively treated patients revealed that patients with an initial kyphosis angle (average age 1y 2m) of less than 40 degrees were significantly less likely to develop progressive kyphosis over the average follow-up period of 3.5 years (mean initial angle 30 degrees and at final follow-up 34 degrees) than those with an angle greater than 40 degrees (mean angle initially 46 degrees and at final follow-up 61 degrees), p=0.005 (repeated measures ANOVA). Seven patients underwent surgical intervention at mean age of 3 years for progressive deformity with favourable results.

Conclusion: Thoracolumbar kyphosis is of variable severity in Hurler’s syndrome and patient’s who present with a kyphosis angle of greater than forty degrees on initial radiographic examination are significantly more likely to develop progressive kyphosis.

Ethics approval: None

Interest Statement: None