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Walking Out of the Curve: Thoracolumbar Kyphosis in Achondroplasia
Adam Margalit1, Greg McKean, Cheryl Lawing
1Department of Orthopaedic Surgery, The Johns Hopkins Hospital, Baltimore, MD.
Insights
Thoracolumbar kyphosis (TLK) in achondroplasia often resolves spontaneously, but 30% of patients have persistent curves. Apical vertebral translation and developmental motor delay are linked to unresolved TLK.
Area of Science:
- Orthopedics
- Pediatric Spine Surgery
- Skeletal Dysplasias
Background:
- Thoracolumbar kyphosis (TLK) is a frequent complication in infants with achondroplasia.
- Understanding the natural history and predictors of persistent TLK is crucial for management.
Purpose of the Study:
- To investigate the natural history of TLK in achondroplasia patients.
- To identify factors associated with the persistence of TLK.
Main Methods:
- Retrospective review of 60 achondroplasia patients with a minimum 2-year follow-up.
- Radiographic assessment of TLK (Cobb angle ≥20°) and associated parameters.
- Clinical evaluation for developmental motor delay and other factors.
Main Results:
- Spontaneous TLK resolution occurred in 15% at walking age and 58% by one year post-walking age.
- Persistent TLK was observed in 30% of patients at final follow-up.
- Apical vertebral translation, vertebral wedging, and developmental motor delay were significantly associated with unresolved TLK.
Conclusions:
- While many achondroplasia patients experience TLK resolution, a significant portion develops persistent curves.
- Early bracing might benefit patients with developmental motor delay.
- Intermittent monitoring is recommended for patients with TLK curves (20-40°) to detect progression or spinal cord compression symptoms.
Background:
Thoracolumbar kyphosis (TLK) is common in infants with achondroplasia. Our goals were to examine the natural history of TLK and identify factors associated with persistent TLK.
Methods:
We reviewed records of patients with achondroplasia seen by a board-certified orthopaedic surgeon at a tertiary care medical center between 1997 and 2013. Inclusion criteria were minimum 2-year follow-up and radiographs taken at time of presentation, within 6 months of walking age, and within 6 months of the first anniversary of walking age. We defined TLK as kyphosis of ≥20 degrees centered at T12 and L1. We assessed patient demographic characteristics, radiographic parameters (Cobb angle, apical vertebral translation, and apical vertebral wedging for vertebral height and width), and clinical parameters (developmental motor delay, hydrocephalus, presence of a ventriculoperitoneal shunt, and foramen magnum decompression). Developmental motor delay was defined as the inability to sit or ambulate independently by age 14 or 30 months, respectively. Associations between these factors and persistent TLK (ie, unresolved at final follow-up) were evaluated using logistic regression and χ, Fisher exact, and independent t tests. Significance was set at P<0.05.
Results:
A total of 60 patients were included. Mean values were as follows: age at presentation, 10.9±7.0 months; length of follow-up, 5.7±3.6 years; initial curve, 43.8±11.0 degrees; independent sitting age, 12.6±5.5 months; and independent walking age, 21.1±7.8 months. At walking age and 1 year after walking age, 15% and 58% of patients, respectively, had spontaneous TLK resolution. In total, 30% of patients had persistent TLK at final follow-up. Apical vertebral translation (P=0.001), percentage of apical vertebral wedging for vertebral height (P=0.031), and developmental motor delay (P=0.043) were associated with unresolved TLK.
Conclusions:
In patients with achondroplasia, TLK resolved at walking age in 15% of patients and after a year of walking in 58% of patients. Earlier bracing may slow TLK progression in patients with achondroplasia and developmental motor delay. Patients with kyphotic curves between 20 and 40 degrees should be examined intermittently for progressive deformity or worsening symptoms of spinal cord compression.
Level Of Evidence:
Level II.
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