Surgical Treatment of Hip Instability in Patients With Lower Lumbar Level Myelomeningocele: Is Muscle Transfer Required?

Background Treatment of hip instability in patients with lower lumbar level myelomeningocele is clinically challenging. Muscle transfer procedures, release of contractures, and intertrochanteric varus-rotation osteotomies have been described to restore weak or absent abductor strength as well as relocation of the hip. However, controlled trials evaluating hip instability in lower lumbar myelomeningocele are limited in the current literature. Questions/purposes The purposes of this study were to compare the (1) radiographic evidence for joint stability; (2) clinical outcomes (including abductor strength, ambulatory ability, and residual use of orthoses); and (3) complications between patients undergoing combined periarticular contracture releases and bony procedures with and without external oblique abdominal muscle transfers. Methods Between 2004 and 2013, 14 pediatric patients (16 hips) were treated for hip instability secondary to myelomeningocele using releases with or without muscle transfer. From those, 13 patients (15 hips) with a mean age of 6 years who had L3 to L5 level involvement were evaluated retrospectively. The patients were separated into two groups. Nine hips (in eight patients) were treated by performing a combination of external oblique abdominal muscle transfer to the greater trochanter, periarticular release of contractures, and bony procedures. These were compared with six hips (five patients) treated by performing a combination of periarticular release of contractures and bony procedures without external oblique abdominal muscle transfer. This study compared the results between two surgeons, one of whom always performed these muscle transfers in this setting and the other who never performed muscle transfer during the study period. The patients were clinically followed up at a mean of 41 months (range, 14–122 months); none of the patients was lost to followup. Radiographic evaluation criteria included Reimer’s migration index, acetabular index, femoral neck-shaft angle, pelvic obliquity, and the presence of scoliosis. Clinical evaluation included muscle strength examination, periarticular contractures, necessity for using orthoses as walking aids, and Hoffer criteria of mobility. All complications were also noted from a chart review. Results There were no differences between the two groups regarding postoperative femoral head localization, reflecting the presence or absence of residual subluxation, according to Reimer’s index (Reimer