Unilateral removal of pars interarticularis

Lumbar radiculopathy secondary to foraminal entrapment can be treated by unilateral removal of the overlying pars interarticularis. The authors prospectively evaluated the outcome after this procedure.

Thirty-six consecutive patients underwent unilateral resection of the pars interarticularis between August 1999 and July 2002. In 18 patients acute foraminal disc herniations compressed the nerve root against the superior pedicle; in the other 18 foraminal stenosis was secondary to degenerative changes. All patients, at each visit, completed the following questionnaires: visual analog scale for overall, leg, and back pain; the Prolo Functional Economic Rating scale; and the Pain Rating Index (PRI) of the Short-Form McGill Pain Questionnaire. At 1 year, leg pain improved in 33 patients (91%). Low-back pain appeared or worsened in eight patients (22%; one in the acute herniation group and seven in the chronic degenerative group). Only one patient required lumbar fusion for pain. The Prolo economic and function scores improved in 21 (58%) and 27 (75%) patients, respectively. The PRI scores improved in 30 cases (83%). No spondylolisthesis was observed at any level at which resection had been performed.

Unilateral removal of the pars interarticularis is effective in relieving lumbar radicular symptoms in patients with intraforaminal entrapment. The incidence of low-back pain in patients with acute foraminal disc herniations does not increase as a result of this procedure. In patients with degenerative foraminal stenosis, unilateral resection of the pars interarticularis may be a better alternative to facetectomy and segmental fusion. This procedure may be a useful tool in spine surgery.