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

Transcription

1 Journal of Orthopaedic Surgery 2006;14(1):21-6 Posterior lumbar interbody fusion versus intertransverse fusion in the treatment of lumbar spondylolisthesis DN Inamdar, M Alagappan, L Shyam, S Devadoss, A Devadoss Department of Orthopaedic Surgery, Institute of Orthopaedic Research and Accident Surgery, Madurai, India 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 Address correspondence and reprint requests to: Prof A Devadoss, Department of Orthopaedic Surgery, Institute of Orthopaedic Research and Accident Surgery, 484-B, KK Nagar, Madurai , India. mdu_ioras@sancharnet.in

2 22 DN Inamdar et al. Journal of Orthopaedic Surgery 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 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 Table 1 Modified Oswestry low back pain disability questionnaire* Pain intensity (5 points) I can tolerate the pain without having to take pain medication. (0) The pain is bad, but I can manage without having to take pain medication. (1) Pain medication provides me with complete relief from pain. (2) Pain medication provides me with moderate relief from pain. (3) Pain medication provides me with little relief from pain. (4) Pain medication has no effect on my pain. (5) Personal care (e.g. washing, dressing; 5 points) I can take care of myself normally without causing increased pain. (0) I can take care of myself normally, but it increases my pain. (1) It is painful to take care of myself, and I am slow and careful. (2) I need help, but I am able to manage most of my personal care. (3) I need help every day in most aspects of my care. (4) I do not get dressed, I wash with difficulty, and I stay in bed. (5) Lifting (5 points) I can lift heavy weights without increased pain. (0) I can lift heavy weights, but it causes increased pain. (1) Pain prevents me from lifting heavy weights off the floor, but I can manage if the weights are conveniently positioned (e.g. on a table). (2) Pain prevents me from lifting heavy weights, but I can manage light-tomedium weights if they are conveniently positioned. (3) I can lift only very light weights. (4) I cannot lift or carry anything at all. (5) Walking (5 points) Pain does not prevent me from walking any distance. (0) Pain prevents me from walking more than one mile (one mile=1.6 km). (1) Pain prevents me from walking more than 1/2 mile. (2) Pain prevents me from walking more than 1/4 mile. (3) I can walk only with crutches or a cane. (4) I am in bed most of the time and have to crawl to the toilet. (5) Sitting (5 points) I can sit in any chair as long as I like. (0) I can only sit in my favorite chair as long as I like. (1) Pain prevents me from sitting for more than 1 hour. (2) Pain prevents me from sitting for more than 30 minutes. (3) Pain prevents me from sitting for more than 10 minutes. (4) Pain prevents me from sitting at all. (5) Standing (5 points) I can stand as long as I want without increased pain. (0) I can stand as long as I want, but it increases my pain. (1) Pain prevents me from standing for more than 1 hour. (2) Pain prevents me from standing for more than 30 minutes. (3) Pain prevents me from standing for more than 10 minutes. (4) Pain prevents me from standing at all. (5) Sleeping (5 points) Pain does not prevent me from sleeping well. (0) I can sleep well only by taking pain medication. (1) Even when I take medication, I sleep less than 6 hours. (2) Even when I take medication, I sleep less than 4 hours. (3) Even when I take medication, I sleep less than 2 hours. (4) Pain prevents me from sleeping at all. (5) Travelling (5 points) I can travel anywhere without increased pain. (0) I can travel anywhere, but it increases my pain. (1) My pain restricts my travel over 2 hours. (2) My pain restricts my travel over 1 hour. (3) My pain restricts my travel to short necessary journeys under 30 minutes. (4) My pain prevents all travel except for visits to the physician/therapist or hospital. (5) Employment/homemaking (5 points) My normal homemaking/job activities do not cause pain. (0) My normal homemaking/job activities increase my pain, but I can still perform all that is required of me. (1) I can perform most of my homemaking/job duties, but pain prevents me from performing more physically stressful activities (e.g. lifting, vacuuming). (2) Pain prevents me from doing anything but light duties. (3) Pain prevents me from doing even light duties. (4) Pain prevents me from performing any job or homemaking chores. (5) * The questionnaire has 9 categories and is modified from the Oswestry low back disability index to suit the need of Indian patients. 0 20% represents minimal disability, 20 40% moderate disability, 40 60% severe disability, 60 80% crippled, and % bed bound

3 Vol. 14 No. 1, April 2006 Comparison of operative treatments of lumbar spondylolisthesis 23 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 <0.05 was considered statistically significant. RESULTS Table 2 Patient characteristics of the 2 groups No. of patients PLIF group ITF group Age (years) Spondylolisthesis Degenerative 5 5 Isthmic 4 5 Traumatic 1 0 Involved parts L4 L5 5 7 L5 S 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. Clinical outcome Preoperative assessment revealed that in the PLIF patients, 90% presented with back pain, 80% with leg pain, 50% with neurological deficit, and one patient had a chronic cauda equina lesion. In the ITF patients, 70% presented with back pain, 100% with leg pain, and 20% with neurological deficit. Postoperatively, complete relief of back pain was achieved in 80% of patients who underwent PLIF and 70% had complete relief of radicular leg pain. In patients who underwent ITF, back pain was relieved in all cases and 80% had relief of radicular leg pain. Motor deficit was relieved in 70% of the PLIF patients, and all ITF patients (Table 3). The condition of the PLIF patient with cauda equina lesion persisted. Assessment of clinical outcome was based on the score of the Oswestry low back pain disability questionnaire 3 ( 20%, excellent; 21 40%, better; 41 60%, unchanged; and 61%, worse). In the PLIF group, the mean preoperative and postoperative Oswestry scores were 25.1 (55%) and 10.4 (22%), respectively, with a mean improvement of 33%. 30% of the patients had an excellent result following surgery, 50% better and 20% unchanged. 80% had satisfactory (excellent or better) results. In the ITF group, 50% had excellent and 50% had better results (i.e. all patients had satisfactory results). The mean preoperative and postoperative Oswestry scores were 20.3 (44%) and 7.5 (16%), respectively, with an Table 3 Comparison of clinical outcome with other studies 7 11 West Zdeblick 9 Suk et al. 11 France et al. 8 Madan and Boeree 7 Present study et al. 10 in 1993 in 1997 in 1999 in 2002 in 1991 Procedure* ITF+PI ITF+PI GF+PI ITF+PI ITF ITF+PI PLIF+PI ITF+PI PLIF+PI ITF+PI (n=23) (n=21) Clinical results Excellent % 45% % 50% Satisfactory % 95% 40% 80% 69.5% 81% 87.5% 100% Listhesis reduction % 28.3% % 27.8% 48% 39% Fusion rate >90% 97% 100% 92.5% 64% 76% % 100% Nonunion % cases - - Back pain relief % 100% Leg pain relief % 70% 80% Motor deficit resolution % 70% 100% * ITF denotes intertransverse fusion, PI posterior instrumentation, GF global fusion, and PLIF posterior lumbar interbody fusion

4 24 DN Inamdar et al. Journal of Orthopaedic Surgery (a) (b) Figure 1 Lateral radiographs of the lumbosacral spine at L5 to S1 levels: (a) preoperative image showing grade-2 spondylolisthesis, and (b) posteroperative image showing a grade-3 fusion after posterior lumbar interbody fusion with posterior instrumentation (arrowhead). (a) (b) Figure 2 Radiographs of the lumbosacral spine at L5 to S1 levels: (a) preoperative lateral view showing grade-1 spondylolisthesis (arrow), and (b) postoperative anteroposterior view showing a grade-3 fusion after intertransverse fusion (arrowhead). improvement of 28%. Reduction of spondylolisthesis According to the Taillard method 4 that measures the degree and percentage of slip, the mean preoperative and postoperative slip in the PLIF group was 27.2% and 14%, respectively, with a mean correction of 48%. The mean preoperative and postoperative slip in the ITF group was 25% and 15.1%, respectively, with a mean correction of 39.2%. Bone union Bone union was graded using radiographs, based on a previously described grading system 6 : grades 0 and 1 were pseudoarthrosis, grades 2 and 3 were good union. No pseudoarthrosis occurred in the PLIF or ITF groups and all patients achieved bone union. In the PLIF group, 20% of patients showed evidence of grade-3 union and 80% grade-2 union (Fig. 1); in the ITF group, 60% of patients showed evidence of grade- 3 union and 40% grade-2 union (Fig. 2). Statistical analysis Comparison of the preoperative and postoperative results for each group revealed that the Oswestry scores of the ITF and PLIF groups were significantly reduced, and the slip in the PLIF group was significantly reduced (Table 4). There was no statistical difference in the postoperative results of the 2

5 Vol. 14 No. 1, April 2006 Comparison of operative treatments of lumbar spondylolisthesis 25 Table 4 Statistical analysis of results of intertransverse fusion (ITF) versus posterior lumbar interbody fusion (PLIF) using Student s t test ITF (n=10) PLIF (n=10) Postoperative Postoperative Oswestry Reduction of Oswestry Reduction of Oswestry reduction of score slip (%) score slip (%) score slip (%) Preop Postop Preop Postop Preop Postop Preop Postop ITF PLIF ITF PLIF Mean Standard deviation p value t value Degrees of freedom Coefficient of variation* (%) Procedure ITF PLIF Oswestry score 53% 60% (clinical results) Reduction of slip 93% 74% (radiological results) * The lower the coefficient of variation, the higher the predictability of the results procedures (Table 4). The coefficient of variation for clinical improvement of the ITF and PLIF groups was 53% and 60%, respectively; the coefficient of variation for radiological slip reduction in the ITF and PLIF groups was 93% and 74%, respectively (Table 4). ITF (53%) was more predictable than PLIF (60%) in reducing the Oswestry scores; PLIF (74%) was more efficient and predictable than ITF (93%) in reducing the slip. Complications In the PLIF group, one patient had a pelvic fracture at the graft harvest site after a fall one month postoperatively and was treated conservatively. Another patient had persistent leg pain at one-year follow-up due to previously undiagnosed bilateral osteoarthritis of the hip. Two patients complained of unresolved back pain following surgery. The condition of the patient with cauda equina lesion remained unresolved at 6-month follow-up. Two patients had persistent back and leg pain. Two patients had unresolved neurological deficit and pedicle screw breakage occurred in another. In the ITF group, only one patient had persistent leg pain at 3-year follow-up but no other complications. No patients developed wound healing problems or infection, but a few had persistent pain at the graft harvest site. DISCUSSION Current surgical options for symptomatic spondylolisthesis are decompression and posterior instrumentation, with either ITF or PLIF. Comparison of this study and other studies 7 11 was performed (Table 3). Suk et al. 11 compared global fusion and posterior instrumentation with ITF and posterior instrumentation and obtained 97% satisfactory (75% excellent) results with global fusion and 95% satisfactory (45% excellent) results with ITF. Madan and Boeree 7 compared 23 patients who underwent instrumented PLIF with 21 patients who underwent instrumented ITF. The clinical outcome was satisfactory in 69.5% of patients who underwent instrumented PLIF and 81% of patients who underwent ITF. Radicular leg pain was improved in 88% and motor deficit in 60% of the ITF patients. France et al. 8 evaluated 71 patients who underwent ITF with or without instrumentation for degenerative spondylolisthesis. 80% and 40% satisfactory results were reported for the groups with and without instrumentation, respectively. For patients with isthmic spondylolisthesis, 63% satisfactory results were obtained without instrumentation. In our series, 87.5% satisfactory results (37.5% excellent, 50% better, and 12.5% unchanged) were reported in the PLIF group, and 100% satisfactory results (50% excellent and 50% better) in the ITF group. Our results are in accordance with those of Suk et al. 11 The lower satisfactory rates in patients who underwent PLIF may have been due to the occurrence of complications such as pelvic fracture and detection of previously undiagnosed bilateral arthritis of the hip. When these 2 patients are excluded, satisfactory scores improve to 87.5% (37.5% excellent and 50% better).

6 26 DN Inamdar et al. Journal of Orthopaedic Surgery This is a realistic assessment and in agreement with most other studies. Suk et al. 11 reported that 41.6% of global fusion patients and 28.3% of ITF patients had reduced slip. Madan and Boeree 7 reported that 61% of global fusion patients and 27.8% of ITF patients had reduced slip. In this study, the reduction of slip was 48% in PLIF patients and 39% in ITF patients. PLIF patients in this study had better results compared with other studies. The bone union rates have been uniformly better in ITF patients in almost all studies. Suk et al. 11 obtained 100% fusion rate for the global fusion series and 7.5% incidence of nonunion in the ITF cases. Zdeblick 9 reported solid fusion in 97% of patients who underwent ITF with posterior instrumentation. West et al. 10 reported over 90% fusion rates in their ITF series. Madan and Boeree 7 reported 2 nonunion cases in ITF patients and none in the PLIF patients. France et al. 8 reported a 64% fusion rate for ITF without instrumentation and 76% for ITF with instrumentation. The fusion rate for ITF patients in this study was better than that reported in other series. No patient in our study had any evidence of nonunion. Nonetheless, the reliability of radiological assessment of fusion has been reported to be only 68%. 6 PLIF is more reliable than ITF in correcting spondylolisthesis and maintaining postoperative results, although fusion rates are better following ITF. Student s t test showed that both ITF and PLIF surgery effectively reduce Oswestry score. Spondylolisthesis was significantly reduced in PLIF patients (p<0.05) but not in ITF patients. There was no significant difference between the 2 procedures in postoperative Oswestry score or reduction of slip (Student s t test, p>0.05). The coefficient of variation was thus applied to the results to determine which procedure is more effective. The coefficient of variation showed that ITF (53%) was more predictable than PLIF (60%) in reducing the Oswestry scores, whereas PLIF (74%) was more efficient and predictable than ITF (93%) in reducing the slip (Table 3). ITF provided better relief of back and leg pain and better resolution of motor deficit. More morbidity and complications were encountered in the PLIF patients because it is a difficult and dangerous procedure that may result in graft protrusion, neural injury, excessive bleeding, and increased operating time. Suk et al. 11 believe that these are due to difficult interbody techniques, that can be overcome by simplifying the techniques and using peripheral cancellous bone chips and a single tricortical block. CONCLUSION Both ITF and PLIF effectively reduce the clinical Oswestry score and the radiological slip (Student s t test, p<0.05). ITF (100% satisfactory) achieves a greater improvement in clinical symptoms and Oswestry scores than PLIF (87.5% satisfactory). PLIF (48% correction) provides better reduction of spondylolisthesis than ITF (39% correction). The fusion rates in both ITF and PLIF patients were equal (100%). There was no incidence of pseudoarthrosis in any of our patients. Morbidity and complications are much higher in patients who undergo PLIF. ITF is recommended because the procedure is simple to perform, with a lower complication rate, and good clinical and radiological results. REFERENCES 1. Wiltse LL, Newman PH, Macnab I. Classification of spondylolisis and spondylolisthesis. Clin Orthop Relat Res 1976;117: Laurent LE, Osterman K. Operative treatment of spondylolisthesis in young patients. Clin Orthop Relat Res 1976;117: Fairbank JC, Couper J, Davies JB, O Brien JP. The Oswestry low back disability questionnaire. Physiotherapy 1980;66: Wiltse LL, Winter RB. Terminology and measurement of spondylolisthesis. J Bone Joint Surg Am 1983;65; Meyerding HW. Spondylolisthesis. Surg Gynecol Obstet 1932;54: Kant AP, Daum WJ, Dean SM, Uchida T. Evaluation of lumbar spine fusion. Plain radiographs versus direct surgical exploration and observation. Spine 1995;20: Madan S, Boeree NR. Outcome of posterior lumbar interbody fusion versus posterolateral fusion for spondylolytic spondylolisthesis. Spine 2002;27: France JC, Yaszemski MJ, Lauerman WC, Cain JE, Glover JM, Lawson KJ, et al. A randomized prospective study of posterolateral lumbar fusion. Outcomes with and without pedicle screw instrumentation. Spine 1999;24: Zdeblick TA. A prospective, randomized study of lumbar fusion. Preliminary results. Spine 1993;18: West JL 3rd, Ogilvie JW, Bradford DS. Complications of the variable screw plate pedicle screw fixation. Spine 1991;16: Suk SI, Lee CK, Kim WJ, Lee JH, Cho KJ, Kim HG. Adding posterior lumbar interbody fusion to pedicle screw fixation and posterolateral fusion after decompression in spondylolytic spondylolisthesis. Spine 1997;22: