Spontaneus bilateral pedicle fracture 30 years after Harrington Instrumentation for idiopathic scoliosis: a case report

Can posterior implant removal prevent device-related vertebral osteopenia after posterior fusion in adolescent idiopathic scoliosis? A mean 29-year follow-up study

PURPOSE

To determine whether posterior implant removal prevents stress-shielding-induced vertebral osteopenia within the posterior fusion area in surgically treated patients with adolescent idiopathic scoliosis (AIS).

METHODS

Eighteen patients with major thoracic AIS (mean age, 43.3 years; range, 32-56 years; mean follow-up, 28.8 years, range, 20-39 years) who underwent posterior spinal fusion (PSF) alone between 1973 and 1994 were included. Participants were divided into implant removal (group R, n = 10, mean interval until implant removal, 50 months) and implant non-removal groups (group NR, n = 8). Bone mineral density was evaluated using the Hounsfield units (HU) of the computed tomography image of the full spine. The HU values of the UIV-1 (one level below the uppermost instrumented vertebra), apex, LIV+1 (one level above the lowermost instrumented vertebra), and LIV-1 (one level below the lowermost instrumented vertebra; as a standard value) were obtained. Stress-shielding-induced osteopenia was assessed as the UIV-1/LIV-1, apex/LIV-1, and LIV+1/LIV-1 HU ratios (× 100).

RESULTS

Overall (median, 25th-75th percentile), the apex (144.7, 108.6-176.0) and LIV+1 (159.4, 129.7-172.3) demonstrated lower HU values than LIV-1 (180.3, 149.2-200.2) (both comparisons, p < .05). Comparison of groups R and NR showed no significant differences in the scoliosis correction rate, bone mineral density of the proximal femur, the HU absolute values of all investigated vertebrae, or in the HU ratios of the investigated vertebrae to LIV-1.

CONCLUSION

Instrumented PSF causes stress-shielding-induced osteopenia of the vertebral body within the fusion area in adulthood, which cannot be prevented by posterior implant removal, probably due to firm fusion mass formation. These slides can be retrieved under Electronic Supplementary Material.

Extraosseous Findings on Bone Scintigraphy Using Fusion SPECT/CT and Correlative Imaging

OBJECTIVE

Extraosseous radioactivity outside of the expected biodistribution is often encountered on (99m)Tc-methylene diphosphate (MDP) bone scintigraphy, and proper interpretation requires an understanding of the mechanisms underlying this uptake and knowledge of the possible causes, depending on the site or structure involved.

CONCLUSION

We present examples of extraosseous radiotracer uptake seen on (99m)Tc-MDP bone scans in which either SPECT with integrated CT or correlative imaging improved the study's interpretation.

Late Fracture After Long Spinal Fusion for Idiopathic Scoliosis: A Case Report

STUDY DESIGN

Case report.

OBJECTIVES

To report a case of late atraumatic fracture of a long spinal fusion for idiopathic scoliosis 37 years after removal of instrumentation and review the literature on this complication.

SUMMARY OF BACKGROUND DATA

Late fracture of a long spinal fusion performed for idiopathic scoliosis is rare, with only several cases reported in the literature.

METHODS

The authors report a case of atraumatic fracture of a long fusion mass in a 55-year-old woman who underwent spinal fusion with Harrington rods at age 14 years with Harrington rod removal at age 18 years. She subsequently developed flat-back syndrome at age 49 years and underwent L3-4, L4-5, and L5-S1 Smith-Peterson osteotomies and posterolateral segmental instrumentation fusion from T12 to pelvis. She developed acute-onset mid-thoracic pain after a minor twisting injury without radiation or neurologic deficit, and was found on magnetic resonance imaging to have a fracture through the fusion mass at T6-7 with increased activity at this location on bone scan.

RESULTS

The patient failed conservative treatment with a high custom-molded brace and underwent posterior segmental spinal instrumentation and fusion from T2 to the previous instrumentation at L2 with autograft and allograft. She had immediate improvement of back pain postoperatively and has recovered well from the surgery.

CONCLUSIONS

Late fracture through a long fusion mass is a rare long-term complication of spine fusion for idiopathic scoliosis. In this case report, we report successful treatment of a fracture with a long lever arm of a solid posterior fused spine with posterior instrumented fusion multiple levels above and below the fracture.