Pelvic fixation of growing rods: comparison of constructs.

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.