Posterior lumbar interbody fusion versus intertransverse fusion in the treatment of lumbar spondylolisthesis

Journal of Orthopaedic Surgery, Apr 2006 by Inamdar, D N, Alagappan, M, Shyam, L, Devadoss, S, Devadoss, A

ABSTRACT

Purpose. To compare 2 methods of fusion in the treatment of lumbar spondylolisthesis: posterior lumbar interbody fusion (PLIF) and intertransverse fusion (ITF).

Methods. 20 patients with lumbar spondylolisthesis were randomly allocated to one of 2 groups: decompression, posterior instrumentation, and PLIF (n=10) or decompression, posterior instrumentation, and ITF (n=10). The Oswestry low back pain disability questionnaire was used for clinical assessment. Radiography was performed preoperatively and postoperatively to assess the reduction of spondylolisthesis or slip.

Results. In the PLIF and ITF groups, 87.5% and 100% had a satisfactory clinical result, and 48% and 39% had reduced spondylolisthesis, respectively. Both had a fusion rate of 100%. PLIF showed better reduction of spondylolisthesis, although ITF achieved a better subjective and clinical outcome.

Conclusion. Morbidity and complications are much higher following PLIF than ITF. ITF is recommended because of the simplicity of the procedure, lower complication rate, and good clinical and radiological results.

Key words: decompression, surgical; low back pain; lumbar vertebrae; outcome assessment; spinal fusion; spondylolisthesis

INTRODUCTION

Lumbar spondylolisthesis is a heterogeneous disorder characterised by the forward displacement of one vertebra on another. It has been classified into 5 types.1 Conservative treatment for segmental instability is possible for patients with tolerable pain. Surgery is indicated if symptoms are disabling and interfere with work, if the condition is progressive, or if there is a significant neurological deficit.

Posterior intertransverse fusion (ITF) in situ is usually performed for children and is successful.2 Decompression can be performed if neurological signs appear. ITF with decompression or posterior lumbar interbody fusion (PLIF) with posterior instrumentation can be performed for adults. Both PLIF and ITF have been used in the treatment of lumbar spondylolisthesis with varying results. To the best of our knowledge, this is the first prospective study to compare the 2 methods.

MATERIALS AND METHODS

The study was conducted at the Institute of Orthopaedic Research and Accident Surgery, India from January 1999 to October 2003. All patients with lumbar spondylolisthesis (grades 1-4) and symptoms severe enough to warrant surgery were included. Preoperative variables were recorded including age, sex, medical history, clinical findings, and type and grade of spondylolisthesis.

Decompression, posterior instrumentation, and either ITF or PLIF was performed in 22 patients with isthmic and degenerative lumbar spondylolisthesis by a single surgeon. Patients were randomly assigned to ITF or PLIF.

The Oswestry low back pain disability questionnaire,3 modified to suit Indian patients and conditions, provided a clinical assessment of low back pain. Nine categories were assessed: pain intensity, personal care, lifting, walking, sitting, standing, sleeping, travelling, and employment/homemaking. Each category was assigned 5 points, with a maximum score of 45. The lower the score, the less the disability (Table 1).

Spondylolisthesis or slip were measured using anteroposterior and lateral radiographs.4 The grade or amount of slip according to Meyerding,5 the percentage of slip, and the sacrohorizontal angle were measured. Indications for surgery were neurogenic claudication, neurological deficits, severe persistent backache, high-grade slip with instability, and back pain not relieved by conservative treatment.

The surgery performed was decompression and posterior instrumentation (pedicle screws; Moss Miami, DePuy, Warsaw [IN], US), with either ITF or PLIF. A tricortical bone graft from the iliac crest was used for PLIF patients: spinous process mixed with bone graft substitute was used for patients undergoing ITF.

Presence of back pain, leg pain, neurological deficits, and straight leg raise were evaluated at one, 3, 6, and 12 months after surgery. Clinical (Oswestry low back pain disability questionnaire) and radiological assessments (reduction of spondylolisthesis) were performed at each follow-up. Bone union was graded on radiographs: grade 0, no visible gap; grade 1, amorphous noncontiguous bone; grade 2, amorphous contiguous bone; grade 3, trabecular bone. Statistical analysis of the results was made using the Student's t test and coefficient of variation to evaluate the efficacy of both procedures in reducing the Oswestry score and the slip. A p value of

RESULTS

11 patients received ITF and another 11 patients received PLIF. One patient from each group was lost to follow-up. The mean age of the 10 patients who underwent PLIF and completed follow-up was 41.4 years, and that of the 10 patients who underwent ITF was 44.7 years (Table 2). The mean operating time was 4 hours for PLIF patients and 3 hours for ITF patients; mean blood loss for both groups was 500 ml. A lumbosacral corset was worn for 4 months. No patients had wound healing problems. The mean follow-up period was one year for PLIF cases and one year 11 months for ITF cases.