Hip Status and Long-term Functional Outcomes in Spina Bifida

Nearly 50% of individuals with myelomeningocele will develop a dislocated hip by skeletal maturity. The purpose of this study was to determine the influence of hip status on functional outcomes in a cohort of adult patients with myelomeningocele.

Patients with a diagnosis of myelomeningocele >18 years were prospectively enrolled over a 12-month period. Neurological level of involvement was obtained from chart review and interview. Clinical examination included hip range of motion and leg-length discrepancy. Reimer's migration index was calculated from a current anteroposterior pelvic radiograph. All subjects completed the VR-12 and the NIH PROMIS outcomes measures for pain interference and physical function. The χ, the Pearson correlation coefficients, and linear regression models were applied to evaluate the influence of hip status on functional outcomes.

In total, 31 patients (average age 31, range 19 to 49) were included. Eight thoracic, 9 lumbar, and 14 sacral level patients participated. Twenty had bilaterally located hips, 5 had a unilateral subluxation or dislocation, and 6 had bilaterally subluxated or dislocated hips. In univariate analysis, patients with bilaterally located hips performed better in lower extremity function than those with unilateral subluxation/dislocation (36.7 vs. 26.0; P=0.03) but worse in pain interference than those with bilateral subluxation/dislocation (52.0 vs. 43.3; P=0.03). After controlling for neurological level, there was no statistically significant difference in the VR-12 mental (P=0.32) or physical component summary (P=0.32) scores, nor in the PROMIS lower extremity function (P=0.26) or pain interference scores (P=0.33) between groups. Decreased extension and abduction were indirectly correlated with VR-12 mental component scores (P=0.0038, 0.0032). Leg-length discrepancy was not associated with any outcome measure.

Long-term outcomes are not associated with hip status in adult patients with myelomeningocele. Functional outcomes are more closely correlated with neurological level and hip range of motion. These results suggest efforts to keep myelomeningocele hips reduced are likely without functional benefit and should be avoided in favor of maintaining motion with contracture release as needed.

Level III.