Anterior dislodgement of a fusion cage after transforaminal lumbar interbody fusion for the treatment of isthmic spondylolisthesis

Abstract

Transforaminal lumbar interbody fusion (TLIF) is commonly used procedure for spinal fusion. However, there are no reports describing anterior cage dislodgement after surgery. This report is a rare case of anterior dislodgement of fusion cage after TLIF for the treatment of isthmic spondylolisthesis with lumbosacral transitional vertebra (LSTV). A 51-year-old man underwent TLIF at L4-5 with posterior instrumentation for the treatment of grade 1 isthmic spondylolisthesis with LSTV. At 7 weeks postoperatively, imaging studies demonstrated that banana-shaped cage migrated anteriorly and anterolisthesis recurred at the index level with pseudoarthrosis. The cage was removed and exchanged by new cage through anterior approach, and screws were replaced with larger size ones and cement augmentation was added. At postoperative 2 days of revision surgery, computed tomography (CT) showed fracture on lateral pedicle and body wall of L5 vertebra. He underwent surgery again for paraspinal decompression at L4-5 and extension of instrumentation to S1 vertebra. His back and leg pains improved significantly after final revision surgery and symptom relief was maintained during follow-up period. At 6 months follow-up, CT images showed solid fusion at L4-5 level. Careful cage selection for TLIF must be done for treatment of spondylolisthesis accompanied with deformed LSTV, especially when reduction will be attempted. Banana-shaped cage should be positioned anteriorly, but anterior dislodgement of cage and reduction failure may occur in case of a highly unstable spine. Revision surgery for the treatment of an anteriorly dislodged cage may be effectively performed using an anterior approach.

Keywords: Cage; Lumbosacral spine; Spondylolisthesis; Transforaminal lumbar interbody fusion; Transitional vertebra.

Fig. 1

Preoperative plain radiographs (A) and CT (B) showing a L4-5 grade I isthmic spondylolisthesis, dysplastic L5 body (back arrow) and lumbosacral transitional vertebra which consists of a bony union between an L5 transverse process and the sacrum on the left side (white arrow).

Fig. 2

Immediate postoperative radiographs showing a good reduction of the spondylolisthesis and a well-positioned fusion cage.

Fig. 3

Plain radiographs (A) and CT sagittal and coronal reconstruction images (B) at postoperative 7 weeks. A : Anterior dislodgement of the fusion cage as well as reduction loss of the spondylolisthesis at the L4-5 level. B : CT images showing that the intervertebral space was not fused and the L4 pedicle screws were loose with osteolysis (white arrows).

Fig. 4

Plain radiographs (A) and CT images (B) after the first revision surgery. A : The pedicle screws were unstable and replaced with thicker and longer ones, but two L4 screws remained loose. Therefore, cement was used to augment the L4 screws. B : CT images showing the pedicle and lateral body wall fracture in the L5 vertebra (white arrows).

Fig. 5

Plain radiographs after the second revision surgery showing the removal of the left L5 screw and bilateral extension of the pedicle screw fixation to S1.