Revision surgery after rod breakage in a patient with occipitocervical fusion: A case report

Abstract

Rationale: Rod breakage after occipitocervical fusion (OCF) has never been described in a patient who has undergone surgery for basilar invagination (BI) and atlantoaxial dislocation (AAD). Here, we present an unusual but significant case of revision surgery to correct this complication.

Patient concerns: A 32-year-old female presented with neck pain, unstable leg motion in walking, and also BI with AAD. Her first surgery was planned to correct these conditions and for fusion at the occipital junction (C3-4) using a screw-rod system. At the 31-month follow-up after her first operation, the patient complained of severe neck pain and limitation of motion, suggesting rod breakage.

Diagnoses: Rod breakage after occipitocervical fusion for BI and AAD.

Interventions: The patient underwent reoperation for replacement of the broken rods, adjustment of the occipitocervical angle, maintenance of the bone graft bed, and fusion.

Outcomes: At follow-up, the hardware was found to be in good condition, with no significant loss of cervical lordosis. At the 37-month follow-up after her second operation, the patient was doing better and continuing to recover.

Lessons: We concluded that nonideal choice of occipitocervical angle may play an important role in rod breakage; however, an inadequate bone graft and poor postoperative fusion may also contribute to implant failure.

Figure 1

(A–C) X-ray taken in the lateral neutral position before surgery, showing the high position of the odontoid and atlantoaxial dislocation with an occipital-C2 angle (OC2A) of 5.1 degrees and a posterior occipitocervical angle (POCA) of 130.6 degrees. (D, E) Cervical 3-dimensional computed tomography reconstruction revealing an atlanto-occipital malformation and C2-3 fusion. Line (a) indicates the inferior aspect line of C2; line (b) indicates the inferior aspect of C3; these 2 lines are parallel. ADI = atlas-dens interval, CMA = cervicomedullary angle (angle subtended by the lines drawn parallel to the ventral surfaces of the medulla and upper cervical cord), OC2A = occipital-C2 angle (angle between McGregor line and the line tangential to the inferior aspect of the axis), POCA = posterior occipitocervical angle (angle formed by the intersection of a line drawn tangential to the flat posterior aspect of the occiput and the line determined by the posterior aspect of the third and fourth cervical facets).

Figure 2

(A) X-ray taken in the lateral neutral position soon after the first surgery and ambulation. (B, C) Imaging data from 13-month follow-up after the first surgery. X-ray indicates subaxial kyphosis with a cervical spine angle (CSA) of −5.8 degrees. Computed tomography reconstruction shows incomplete fusion at the occipitocervical junction. CSA =  cervical spine angle (angle between the posterior aspects of vertebral bodies C2 and C7).

Figure 3

(A) Plain cervical radiographs taken at 31-month follow-up after the first operation showing breakage of the right rod in the region of the occipitocervical junction. (B, C) Lateral x-rays in flexion-extension positions show subaxial cervical instability. (D) Computed tomography scan indicates inadequate fusion of bone graft.

Figure 4

(A) Lateral x-ray after revision surgery showing correct position with an occipital-C2 angle (OC2A) of 9.5 degrees and posterior occipitocervical angle of 117.8 degrees. (B) Lateral x-ray at follow-up 37 months after revision surgery.