Pelvic fixation of growing rods: comparison of constructs.

ABSTRACT

STUDY DESIGN: Retrospective review. OBJECTIVE: To analyze outcomes and complications of growing rods fixed to the pelvis. SUMMARY OF BACKGROUND DATA Growing systems with pelvic foundations are used for neuromuscular/syndromic scoliosis. There is little data comparing different constructs. This project analyzed the outcomes and complications of this population. METHODS: Records/radiographs of 36 patients from the Growing Spine database with growing rods anchored in the pelvis were studied. Diagnoses included spinal muscular atrophy-6, cerebral palsy-5, myelomeningocele-5, congenital-4, arthrogryposis-1, and miscellaneous/syndromic-15. Age at surgery was 6.8 +/- 3 years. Preoperative curve was 86 degrees +/- 22 degrees and pelvic obliquity was 27 degrees +/- 11 degrees . Follow-up was 40 +/- 23 months. Rod breakage rate was compared to that of 299 patients not fixed to the pelvis. RESULTS: Iliac screws were used in 20 patients, iliac rods in 10, S-rods in 3, and sacral fixation in 6. Dual rods were used in 30 patients; single in 6. At follow-up, mean Cobb improved to 48 degrees +/- 20 degrees and pelvic obliquity improved to 11 degrees +/- 7 degrees . Iliac screws achieved significantly better Cobb and pelvic obliquity correction than sacral fixation (47% vs. 29%, P = 0.04, 66% vs. 40%, P = 0.001). Pelvic obliquity correction exceeded major curve correction (P < 0.001). Total gain in T1-S1 length was 8.6 +/- 4.3 cm; gain during lengthenings was 4.0 +/- 4.7 cm. Bilateral rods provided better correction of both pelvic obliquity (67% vs. 44%, P = 0.006) and major curve (47% vs. 25%, P = 0.02) than unilateral rods. Six patients have undergone final fusion at mean 3.3 +/- 1.8 years after initial surgery. Five patients developed deep infections. There were 6 rod breakages; this rate did not differ from constructs not anchored in the pelvis (P = 0.36). There were 5 breakages of iliac screws and none of other anchors (P = 0.035). CONCLUSION: Growing rods can include pelvic fixation to correct pelvic obliquity or obtain adequate fixation. Dual iliac fixation provides the best correction. Both iliac screws and rods provide satisfactory distal fixation; iliac screws had a higher rate of breakage. Growing rods with pelvic fixation are effective in deformity correction and achieving growth.