Adjacent segment stenosis after lumbar fusion requiring second operation

J Orthop Sci (2005) 10:490–495 DOI 10.1007/s00776-005-0919-3

Original article Adjacent segment stenosis after lumbar fusion requiring second operation Hikono Aiki1,2, Osamu Ohwada1, Hiroji Kobayashi1, Mitsuru Hayakawa1, Satoshi Kawaguchi2, Tsuneo Takebayashi2, and Toshihiko Yamashita2 1 2

Sapporo Minami Orthopaedic Hospital, Sapporo, Japan Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, South 1, West 16, Chuo-ku, Sapporo 060-8543, Japan

Abstract Background. Whereas degeneration of the segment adjacent to lumbar fusion has been often seen on radiographs, a small number of patients with such degenerative changes undergo reoperation. Most follow-up studies have focused on adjacent segment disease based on analysis of radiographs. The present study was conducted to understand the pathology of reoperation cases of adjacent segment disease and factors associated with this condition. Operative indication was consistently restricted to patients with neurological involvement. Methods. The subjects were 117 patients who had undergone posterior lumbar fusion and were followed for a minimum of 2 years (mean 7 years). Among them, nine patients (7.7%) required a second operation owing to symptomatic adjacent segment disease (stenosis). The reoperation rate was assessed in relation to sex, age, initial pathologic condition, and initial spinal fusion and decompression methods. Data were analyzed in a 2 ¥ 2 cross contingency table using Fisher’s exact probability test. A probability of <0.05 was defined as statistically significant. Results. Of the variables examined, only multilevel fusion was associated with a high rate of reoperation with statistical significance (P < 0.04). Two patients (100%) suffering from loss of coronal balance (degenerative scoliosis) also required a second operation. Conclusions. The reoperation rate of 7.7% for adjacent segment disease in this study was consistent with the prevalence of adjacent segment stenosis in the literature. Given the risk of later occurrence of adjacent segment stenosis following multisegment posterolateral fusion, correction of coronal and sagittal balance, preventive decompression of the adjacent segment, or selective decompression without fusion may have to be considered as an additional or alternative procedure.

Introduction Spinal fusion is a common procedure for various pathologic conditions. The number of fusion operations of the spine has dramatically increased during the last decade.1 Despite such prevalence of spine fusion procedures, controversy remains regarding some of the fundamental aspects, including the indications for fusion, the preferred surgical procedures, and the subsequent frequency of adjacent segment disease.1,2 Adjacent segment disease is a condition wherein the motion segment adjacent to the fused area degenerates because of hypermobility and increased biomechanical stress.2,3 This condition has been observed radiographically in 30%–53% of patients who were followed for 5 years or more after lumbar fusion surgery.4–11 A small number of these patients, however, required reoperation for adjacent segment disease. The reoperation rate for adjacent segment disease has been reported in the literature to be 0%–18%.4,6,8–11 Whereas several follow-up studies9,10,12 have investigated the risk factors for adjacent segment disease based on analysis of radiographs, investigation focusing on those requiring reoperation for adjacent segment disease has been limited to sectional studies.13–17 In this study, the authors analyzed clinical and radiographic features of patients who had undergone lumbar fusion surgery based on consistent operative indications and who underwent reoperation for adjacent segment disease.

Materials and methods

Offprint requests to: S. Kawaguchi Received: November 10, 2004 / Accepted: June 2, 2005

Between 1988 and 1992, a total of 143 patients with degenerative disease underwent lumbar decompression and fusion carried out by a senior surgeon. The indication for the operation was radicular pain or neuralgic claudication (or both) resistant to conservative treat-

H. Aiki et al.: Stenosis of lumbar adjacent segment

ment. Low back pain alone was not an acceptable indication for operative treatment. Posterior or posterolateral fusion was performed using autogenous iliac bone for patients who had radicular pain or claudication associated with spondylolysis, spondylolisthesis, dynamic instability, or deformity (degenerative scoliosis or kyphosis). Dynamic instability was determined as slippage of more than 3 mm or an angle change of more than 10° on flexion and extension. Inclusion in the study required a minimum follow-up of 2 years. Of the 143 patients, 117 (82%) met this criterion and were the basis of this report. The average follow-up was 7 years (range 2–17 years); 72 patients had a minimum follow-up of 5 years. There were 59 male subjects and 58 female subjects, with an average age of 51 years (range 16–75 years). The diagnosis was degenerative spondylolisthesis in 44 patients, spondylolytic spondylolisthesis in 46, spondylolysis in 8, failed back syndrome in 15, lumbar spine with dynamic instability in 11, degenerative scoliosis in 2, and degenerative kyphosis in 1 patient. All patients underwent posterolateral fusion, except one patient who had undergone posterior fusion (H-graft). Instrumentation was used in 86 patients, including a Luque wire and rod system in 25 patients and a pedicle screw system in 61 patients. One segment was fused in 103 patients, two segments in 11 patients, and three segments in 3 patients. Fusion region was restricted to lumbar vertebrae (floating fusion) in 68 patients and extended to the sacrum in 49 patients. Nerve decompression was performed at the fusion segment(s) in all patients. Also, the segment(s) adjacent to the fusion site was decompressed in 17 patients when there was stenosis, including the upper adjacent segment in 14 patients, the lower segment in 2 patients, and both the upper and lower segments in 1 patient. Bone union was achieved in 110 patients (94%). Patients who were reoperated on for symptoms (radicular pain, neuralgic claudication, or both but not low back pain alone) caused by adjacent segment disease were identified from files. Records of these patients were reviewed to collect clinical data at the first and second operations. Radiographs of the neutral standing position were measured for the whole lumbar spine (sagittal L1-S1 angle and coronal maximum Cobb angle) and the adjacent segment [percent slip, disc angle, and percent posterior disc height (%PDH)]. The degenerative status of the adjacent segment disc was also determined by magnetic resonance imaging (MRI). In addition, the reoperation rate was assessed in relation to sex, age, initial pathologic condition, and initial spinal fusion and decompression methods. Data were analyzed in a 2 ¥ 2 cross contingency table using Fisher’s exact probability test. A probability of less than 0.05 was defined as statistically significant.

491

Patients with symptomatic adjacent segment disease, which had not been severe enough to require operation, were classified as the control group (patients without reoperation). The decision-making for each surgery depended on the relationship between the surgeon and individual patient, which had been consistent between the initial surgery for the primary condition and the subsequent second surgery for the adjacent segment disease.

Results Of 117 patients who had undergone lumbar fusion surgery, 9 (7.7%) required a second operation for adjacent segment disease (Table 1). The average period between the first and second operations was 7 years 1 month (range 2 years 9 months to 11 years 9 months). The pathology at second operation indicated spinal stenosis in all nine patients, combined with spondylolisthesis (four patients), intervertebral instability (two patients), or disc herniation (two patients). These conditions occurred in the upper adjacent segments in seven patients and in the lower adjacent segments in two patients. Preoperative radiographs of the whole lumbar spine showed loss of the L1-S1 sagittal angle (less than 40°) in three patients (cases 6, 7, 8), including two patients who also exhibited coronal imbalance (Table 2). The malalignment seen in those patients remained at the time of the second operation. With respect to the adjacent segment, preoperative MRI revealed degenerative changes of the disc in two of the three patients examined. Fusion was achieved at the intended segment in all nine patients. At the time of the second operation, four patients showed spondylolisthesis, including one retrograde olisthesis. The disc angle became kyphotic in two patients and the %PDH remained unchanged or decreased during the interval between the first and second operations. The reoperation rate was assessed in relation to sex, age, initial spinal fusion method, and decompression method (Fig. 1, Table 3). Male patients, ages 50 years and older, multisegment fusion, floating fusion, instrumentation surgery, and adjacent decompression were associated with a relatively high reoperation rate. Of these variables, multisegment fusion exhibited statistical significance (P = 0.04). The reoperation rate being related to the initial diagnosis was 2.2% for patients with spondylolytic spondylolisthesis, 9.1% for patients with degenerative spondylolisthesis, 9.1% for patients with dynamic instability, and 6.7% for patients with failed back syndrome (Fig. 2). Notably, two patients (100%) with degenerative scoliosis required a second operation for adjacent segment disease.

56

66

51

56

56

52

56

37

63

1

2

3

4

5

6

7

8

9

M

M

M

F

M

F

F

M

M

Sex

Degenerative spondylolisthesis Degenerative spondylolisthesis Degenerative spondylolisthesis Degenerative spondylolisthesis Spondylolitic spondylolisthesis Degenerative scoliosis Degenerative scoliosis Failed back syndrome Unstable spine

Diagnosis

a

PLF, posterolateral fusion; PF, posterior fusion Expressed in years and months

Age

Patients

L3/4

L3-L5

L3-L5

L2-L5

L5-S1

L4/L5

L4/L5

L4/L5

L3/L4

PLF (pedicle screw: Dick) PF (H-graft)

PLF (Luque)

PLF (pedicle screw: Steffee) PLF (pedicle screw: Steffee) PLF (pedicle screw: Steffee) PLF (pedicle screw: Steffee) PLF (Luque)

PLF (Luque)

Type of fusion (instrument)

First operation Fusion level

Table 1. Clinical picture of patients reoperated upon

L3/4

L3/4, L4/5

L2/3, L3/4, L4/5

L2/3, L3/4, L4/5

L5-S1

L4/5

L4/5

L3/4, L4/5

L2/3, L3/4, L4/5

Decompression level

Stenosis; spondylolisthesis

Stenosis; instability; retrograde spondylolisthesis Stenosis

Stenosis; instability

Stenosis

Stenosis; spondylolisthesis

Stenosis

Stenosis; spondylolisthesis; disc herniation Stenosis; disc herniation

Pathology

L4/5

L2/3

L2/3

L1/2

L3/4

L3/4

L3/4

L3/4

L4/5

Level

Second operation

11yr9mo

10yr4mo

6yr2mo

3yr3mo

8yr1mo

10yr7mo

7yr2mo

3yr8mo

2yr9mo

Period from first operationa

492 H. Aiki et al.: Stenosis of lumbar adjacent segment

H. Aiki et al.: Stenosis of lumbar adjacent segment

493

Table 2. Radiographic findings at the first and second operations of patients reoperated upon Whole lumbar spine Patient

Adjacent segment

Sagittal L1-S1 angle

Coronal Cobb angle

Level

MRI

1

40Æ42a

0Æ0

L4/5

2 3 4 5 6 7

42Æ50 52Æ51 65Æ60 43Æ47 33Æ25 15Æ23

0Æ0 0Æ0 0Æ0 0Æ0 26Æ40 25Æ29

L3/4 L3/4 L3/4 L3/4 L1/2 L2/3

8 9

20Æ23 NAÆ42

0Æ0 NAÆ15

L2/3 L4/5

Low signal in T2WI protrusion NA NA No degeneration NA NA Low signal in T2WI protrusion NA NA

% Slip

Disc angleb

% PDH

6Æ6

13.3Æ10.0

5Æ8 4Æ10 11Æ15 11Æ14 3Æ -6 5Æ -5

13.3Æ11.9 20.9Æ11.9 15.8Æ14.7 15.6Æ15.6 18.2Æ18.2 17.5Æ15.0

0Æ17.5 0Æ0 0Æ0 0Æ14.7 0Æ0 0Æ0 7.5Æ12.5 (retro) 0Æ0 NAÆ8.3

5Æ5 NAÆ4

11.9Æ11.9 NAÆ16.7

MRI, magnetic resonance imaging; PDH, posterior disk height; T2WI, T2 weighted image; NA, not available a The left number indicates the status at the first operation, and the right number indicates that at the second operation b Positive disc angle indicates lordosis

Table 3. Rate of reoperation related to variables Rate of reoperation Variables

Fig. 1. Rate of reoperation for adjacent segment disease related to patient’s age

Discussion In the present study, we identified nine patients (7.7%) who had required a second operation for adjacent segment disease following lumbar fusion surgery. According to our operative indications, all of these patients exhibited neurological symptoms and spinal stenosis in addition to adjacent segment degeneration. A comparative analysis with the control group (patients with no second operation) revealed that patients who had undergone multisegment fusion, especially for degenerative scoliosis, showed a high reoperation rate. Table 4 summarizes the literature review, focusing on the rate of adjacent segment disease and reoperation after lumbar fusion. As defined by imaging studies, the rate of adjacent segment disease progressively increases after the first operation. In studies with a mean followup duration of less than 5 years, adjacent segment dis-

Sex Female Male Age <50 Years ≥50 Years No. of fusion segments One segment Multisegments Two segments Three segments Type of fusion Floating fusion Extended to sacrum Instrumentation Yes No Adjacent decompression Yes No

No.

%

P

3/58 6/59

5.2 10.2

0.31

1/41 8/71

2.2 11.3

0.1

6/103 3/14 2/11 1/3

5.8 21.4 18.2 33.3

8/68 1/49

11.8 2.0

0.05

8/86 1/31

9.3 3.2

0.28

3/17 6/100

17.6 6.0

0.24

0.04 0.82

ease has been seen in 5%–25% of patients.12,20–24 In contrast, it has been seen in 30%–53% of patients in studies with an average follow-up of 5 years or more after lumbar fusion surgery.4–11 These findings support the degenerative nature of adjacent segment disease.2,3 In comparison with the relatively high prevalence of adjacent segment disease seen on radiographs, only a small number of patients required reoperation for adjacent segment disease (reported to be 0%–18% in the literature).4,6,8–11,18 In addition to the presence of patients with asymptomatic adjacent segment disease, the difference in surgical indications may have influenced the number

494

H. Aiki et al.: Stenosis of lumbar adjacent segment

of reoperations. Whereas we performed surgery on elected patients with neurological involvement, other studies6,8–11 included degenerative disc diseases that cause only low back pain. In this regard, spinal stenosis in the adjacent segment had developed in 5%–6% of patients after lumbar fusion (Table 4),7,9,10,12,19 consistent with the reoperation rate in the present study. Based on radiographic analysis, several risk factors have been suggested for the later occurrence of adjacent segment disease, including female sex, advanced age (>60 years), multisegment fusion, floating fusion, rigid instrumentation, and loss of coronal or sagittal balance (or both).9,10,12 In sectional studies of reoperation cases with adjacent segment disease13-17 (Table 5), more than half the patients had undergone multisegment fusion. In our analysis, the reoperation rate was significantly higher in patients with multisegment fusion (21.4%) than in those with one-segment fusion (5.8%). Also, two patients (100%) with loss of coronal balance (degenerative scoliosis) required a second operation for adjacent segment disease. For the other risk factors,

Fig. 2. Rate of reoperation for adjacent segment disease related to initial diagnosis. SL, spondylolysis; SS, spondylolytic spondylolisthesis; DS, degenerative spondylolisthesis; DI, dynamic instability; FBS, failed back syndrome; DSc, degenerative scoliosis

Table 4. Review of the literature on rate of adjacent segment disease and reoperation after lumbar fusion Follow-up (years)

Study

No.

Fusion method

Lehmann et al.4 Frymoyer et al.18 Leong et al.5 Roy-Camille et al.6 Penta et al.19 Wiltse et al.7 Gillet8 Rahm and Hall9 Kumar et al.10 Buttermann et al.11 Chou et al.20 Pihlajamaki et al.21 Etebar and Cahill12 Axelsson et al.22 Aota et al.23 Wimmer et al.24 Present study

62 96 40 43 81 83 106 49 83 165 32 63 125 54 65 120 117

PF PF ALIF PLF ALIF PLF PLF PLF (PLIF25) PLF PLF PLF PLF PLF PLF PLF ALIF + PF PLF (PF1)

Minimum 21 10 10 10 10 ND 2 2 2 ND 4 2 ND 2 2 2 2

Mean 33 13.7 12.7 11.5 ND 7 >5 5 5 5 4.6 4 4 3.5 3.4 3 7

Adjacent segment disease (%)

Adjacent segment stenosis (%)a

Reoperation (%)

45 ND 53 43 32 48 38 35 36 30b 19 5 14b 20 25 11 Not determined

ND ND ND ND 5 6 ND 6 5 ND ND ND 5 ND ND ND Not determined

5 5 ND 0 ND ND 18 13 17 9 ND ND ND ND ND ND 8

ALIF, anterior lumbar interbody fusion; PLIF, posterior lumbar interbody fusion; ND, not described a Stenosis determined by computed tomography, magnetic resonance imaging, or myelography was described b Percentage of symptomatic cases

Table 5. Review of the sectional studies for adjacent segment disease requiring reoperation Study

No.

Sex

Age at reoperation (years), mean and range

Long fusion (%)

Floating fusion (%)

Schlegel et al.15 Chen et al.17 Philips et al.16 Lee13 Whitecloud et al.14

58 39 26 18 14

M22, F36 M9, F30 M9, F17 M6, F12 M7, F7

42.6 (12–75) 61 (47–74) 57 (27–78) 38.6 (23–56) 52 (35–75)

71 54 65 77 ND

16 67 19 5 ND

H. Aiki et al.: Stenosis of lumbar adjacent segment

patients with floating fusion and instrumentation showed a higher rate of reoperation than those without such factors, even though there was no statistical significance. Female sex and advanced age were not related to a high reoperation rate. This appears to reflect relatively low activity in groups where a second operation was not often preferred. Our findings indicated a limitation of posterolateral fusion for degenerative lumbar scoliosis and other conditions requiring multisegment fusion. For these conditions, the use of intervertebral cages to correct coronal and sagittal balance during fusion surgery or preventive decompression of the adjacent segment may decrease the development of adjacent segment stenosis. Also, selective decompression without fusion may become an alternative choice. Decompression of the adjacent segment was not a significant risk factor for the subsequent occurrence of instability in the present analysis. It should be noted that spinal stenosis developed at two levels above the fused segment in one patient (case 5). There was no detectable stenosis or remarkable sagittalization at that level (L3/4) on myelography and or computed tomography scans performed prior to the first operation. It remains unknown whether the stenosis developed as a natural course or as a result of fusion of the L5-S1 level in this patient. In this regard, Chen et al.17 included two such cases in a study of 39 patients who underwent second lumbar spinal surgery for adjacent segment disease. The limitations of the present study are the lack of radiographic analysis and incomplete (82%), relatively short follow-up periods. On the other hand, consistency in operative indications and procedures, as well as a comprehensive literature review, gives strength to the study. Conclusions The reoperation rate of 7.7% for adjacent segment disease in this study was consistent with the prevalence of adjacent segment stenosis reported in the literature. Given the risk of later occurrence of adjacent segment stenosis following multisegment posterolateral fusion, correction of coronal and sagittal balance, preventive decompression of the adjacent segment, or selective decompression without fusion may need to be considered as an additional or alternative procedure. References 1. Weinstein JN, Boden SD, An H. Emerging technology in spine: should we rethink the past or move forward in spite of the past? Spine 2003;28:S1. 2. Javedan SP, Dickman CA. Cause of adjacent-segment disease after spinal fusion. Lancet 1999;354:530–1.

495 3. Eck JC, Humphreys SC, Hodges SD. Adjacent-segment degeneration after lumbar fusion: a review of clinical, biomechanical, and radiologic studies. Am J Orthop 1999;28:336–40. 4. Lehmann TR, Spratt KF, Tozzi JE, Weinstein JN, Reinarz SJ, ElKhoury GY, et al. Long-term follow-up of lower lumbar fusion patients. Spine 1987;12:97–104. 5. Leong JC, Chun SY, Grange WJ, Fang D. Long-term results of lumbar intervertebral disc prolapse. Spine 1983;8:793–9. 6. Roy-Camille R, Benazet JP, Desauge JP, Kuntz F. Lumbosacral fusion with pedicular screw plating instrumentation: a 10-year follow-up. Acta Orthop Scand Suppl 1993;251:100–4. 7. Wiltse LL, Radecki SE, Biel HM, DiMartino PP, Oas RA, Farjalla G, et al. Comparative study of the incidence and severity of degenerative change in the transition zones after instrumented versus noninstrumented fusions of the lumbar spine. J Spinal Disord 1999;12:27–33. 8. Gillet P. The fate of the adjacent motion segments after lumbar fusion. J Spinal Disord Tech 2003;16:338–45. 9. Rahm MD, Hall BB. Adjacent-segment degeneration after lumbar fusion with instrumentation: a retrospective study. J Spinal Disord 1996;9:392–400. 10. Kumar MN, Baklanov A, Chopin D. Correlation between sagittal plane changes and adjacent segment degeneration following lumbar spine fusion. Eur Spine J 2001;10:314–9. 11. Buttermann GR, Garvey TA, Hunt AF, Transfeldt EE, Bradford DS, Boachie-Adjei O, et al. Lumbar fusion results related to diagnosis. Spine 1998;23:116–27. 12. Etebar S, Cahill DW. Risk factors for adjacent-segment failure following lumbar fixation with rigid instrumentation for degenerative instability. J Neurosurg 1999;90:163–9. 13. Lee CK. Accelerated degeneration of the segment adjacent to a lumbar fusion. Spine 1988;13:375–7. 14. Whitecloud TS III, Davis JM, Olive PM. Operative treatment of the degenerated segment adjacent to a lumbar fusion. Spine 1994;19:531–6. 15. Schlegel JD, Smith JA, Schleusener RL. Lumbar motion segment pathology adjacent to thoracolumbar, lumbar, and lumbosacral fusions. Spine 1996;21:970–81. 16. Phillips FM, Carlson GD, Bohlman HH, Hughes SS. Results of surgery for spinal stenosis adjacent to previous lumbar fusion. J Spinal Disord 2000;13:432–7. 17. Chen WJ, Lai PL, Niu CC, Chen LH, Fu TS, Wong CB. Surgical treatment of adjacent instability after lumbar spine fusion. Spine 2001;26:E519–24. 18. Frymoyer JW, Hanley E, Howe J, Kuhlmann D, Matteri R. Disc excision and spine fusion in the management of lumbar disc disease: a minimum ten-year followup. Spine 1978;3:1–6. 19. Penta M, Sandhu A, Fraser RD. Magnetic resonance imaging assessment of disc degeneration 10 years after anterior lumbar interbody fusion. Spine 1995;20:743–7. 20. Chou WY, Hsu CJ, Chang WN, Wong CY. Adjacent segment degeneration after lumbar spinal posterolateral fusion with instrumentation in elderly patients. Arch Orthop Trauma Surg 2002;122:39–43. 21. Pihlajamaki H, Bostman O, Ruuskanen M, Myllynen P, Kinnunen J, Karaharju E. Posterolateral lumbosacral fusion with transpedicular fixation: 63 consecutive cases followed for 4 (2–6) years. Acta Orthop Scand 1996;67:63–8. 22. Axelsson P, Johnsson R, Stromqvist B, Arvidsson M, Herrlin K. Posterolateral lumbar fusion: outcome of 71 consecutive operations after 4 (2–7) years. Acta Orthop Scand 1994;65:309–14. 23. Aota Y, Kumano K, Hirabayashi S. Postfusion instability at the adjacent segments after rigid pedicle screw fixation for degenerative lumbar spinal disorders. J Spinal Disord 1995;8:464–73. 24. Wimmer C, Gluch H, Krismer M, Ogon M, Jesenko R. APtranslation in the proximal disc adjacent to lumbar spine fusion: a retrospective comparison of mono- and polysegmental fusion in 120 patients. Acta Orthop Scand 1997;68:269–72.