Posterior Vertebrectomy for Congenital Hemivertebra
Modified Eggshell Procedure

· (c - Depuy Acromed) Loyola University Chicago; Oak Brook Terrace, Illinois, USA

INTRODUCTION: Congenital hemivertebra in thoraco-lumbar, lumbar, and lumbo-sacral spine is prone to cause coronal and sagittal imbalance as well as progressive scoliosis. The management consists of either anterior and posterior fusion, or combined anterior and posterior excision. This report is to present a modification of posterior eggshell operation.

TECHNIQUE: The hemi-vertebra is excised with preservation of its cephalad and caudad cortical end plates. They are compressed together to bring bone to bone contact. The adjacent discs are not violated. This modification makes the procedure easier, will ensure bone to bone union, and will require short fusion and instrumentation, which of utmost importance in the lumbar spine.

MATERIAL AND METHOD: This report presents eight cases, which were managed with this technique. Patients age range from 4+4 to 17+2, average 12+5. Follow up average 36 months with range from 24m to 45m. All had proved progression of the curve that includes the hemivertebra. The location of the hemivertebra was T8 in one patient, T12 in one patient, L1 in two patient, L2 in one patient, L3 in two patients, and L5 in one patient. The case with T12 hemivert the fusion was from T10 to L2. In the patient with L5 hemivert excision, the fusion extended from L3 to sacrum. In all other cases the fusion extended from one level proximal to one level distal to the excised vertebra. All were instrumented with ISOLA system with lumbar pedicle screws, when it is applicable.

RESULTS: The scoliosis curve preop range from 28° to 58°, with average of 47°. On the follow up the range of the curve was 2° to 26° average 12°. All had normal lumbar lordosis on the follow up. All fused with no significant change between the radiographs of postop visit and last follow up visit. There was no intraoperative complication, no neurological complication, no infection, or instrumentation failure.

CONCLUSION: This technique of hemivertebra excision offers the advantages of being easier, one stage procedure, guaranteed union, and short fusion and instrumentation.