Review Question - QID 220540

Adult Isthmic Spondylolisthesis Treatment Operative QID: 220540 (OBQ24.167)

QID 220540 (Type "220540" in App Search)

A 28-year-old female patient undergoes an arthrodesis procedure for the pathology shown in Figure A after failed nonoperative management. During the surgery, the surgeon attempts to correct the deformity. During postoperative examination, the patient is noted to have a motor deficit. Which of the structures shown in Figure B was likely injured with the reduction attempt?

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The patient has L5-S1 spondylolisthesis and is undergoing a fusion procedure. During attempted reduction of the spondylolisthesis, the L5 nerve root can sustain a stretch injury. The L5 nerve root is identified as D in Figure B.

Adult isthmic spondylolisthesis is a common condition characterized by a defect in the pars interarticularis. It is present in approximately four to six percent of the general population. It is usually asymptomatic, and when symptomatic, treatment consists of nonoperative management for most patients. In symptomatic patients, L5-S1 instrumented fusion with or without decompression is a viable treatment option. During instrumented fusion, the L5 nerve root can potentially sustain a stretch injury if a reduction is attempted. The L5 nerve root exits directly below the L5 pedicle, while the S1 nerve is the traversing root at this level.

Katz et al conducted an observational study to determine the history and physical examination signs associated with degenerative lumbar spinal stenosis. The authors evaluated 93 patients aged 40 and above who presented with low back pain. They found that greater age, severe lower extremity pain, and absence of pain while seated were all strongly correlated with lumbar spinal stenosis.

Lauder et al conducted a prospective observational study to determine the relationship between history and physical examination and electrodiagnostic study (EDX) results. They enrolled a total of 170 patients with low back and lower leg symptoms. While the physical examination was better at predicting EDX findings, neither the physical examination nor history could accurately predict the results of EDX testing. Fifteen to eighteen percent of patients without physical examination findings had abnormal EDX results.

Figure A is a lateral radiograph of a patient with L5-S1 spondylolisthesis.

Figure B is a T2 axial MRI slice at the L5-S1 level. A indicates the cerebrospinal fluid inside the thecal sac, B points to the right facet joint, C points to bulging disc material, D points to the left L5 nerve root, and E points to the left traversing S1 nerve root.

Incorrect Answers:
Answers 1,2,3,5: These structures would not be impacted by a reduction maneuver.