The Management of Kyphosis in Metatropic Dysplasia

Abstract

Design: Retrospective review.

Objective: To describe the presentation and progression, and compare treatments of severe thoracic kyphosis in a cohort of patients with metatropic dysplasia.

Summary of background data: Metatropic dysplasia is a rare skeletal dysplasia characterized by several abnormalities, including severe platyspondyly and vertebral wedging. These lead to marked kyphoscoliosis that begins in the first year of life and progresses to a stiff, short thorax and restrictive lung disease. There is no study that specifically addresses treatment of kyphosis in this cohort.

Methods: A 12-year retrospective chart review at a single institution was performed to identify metatropic dysplasia patients. Comparison between four main treatment groups-observation, bracing, anterior release and growing construct, and anterior release and final fusion-were made radiographically with regard to thoracolumbar, T2-T12, and major Cobb kyphosis; sagittal vertical alignment; and C7-kyphosis apex distance, taken at presentation, pre- and posttreatment, and final follow-up.

Results: Twenty patients with metatropic dysplasia presented at an average age of 3.1 years with a kyphosis of 75°, and were followed an average of 8.5 years. Those treated surgically presented with an average of 86.7° kyphosis, 88 mm C7-kyphosis apex distance, and 50 mm positive sagittal vertical alignment (SVA). Postsurgical reduction of kyphosis averaged 43° with less than 4° loss of correction in all groups except the constructs involving rib fixation. Recent use of staged thoracoscopic anterior soft tissue release, halo traction, and growing rod construct has produced the most dramatic results with average kyphosis correction of 71° and evidence of anterior bony remodeling. In those treated with observation, kyphosis progressed less than a quarter degree per year.

Conclusions: Thoracic kyphosis in metatropic dysplasia does not uniformly progress in all patients and therefore can be initially observed. In those who progress, several surgical options exist including growth-friendly constructs that have demonstrated success without a higher rate of complications.

Level of evidence: Level IV.

Keywords: Kyphoscoliosis; Kyphosis; Metatropic dysplasia; Skeletal dysplasia; Skeletal dysplasia spine.