Outcomes of Posterior Fusion Using Pedicle Screw Fixation in Patients ≥ 70 Years With Lumbar Spinal Canal Stenosis

Abstract

Pedicle screw fixation is frequently used for spinal fusion in elderly patients. The application of pedicle screw fixation for elderly patients with degenerative lumbar disease remains controversial due to problems such as surgical invasion, osteoporosis, and cost performance. Outcomes of spinal fusion using pedicle screw fixation were evaluated in patients older than 70 years with lumbar spinal canal stenosis. Eighty-one patients older than 70 years with degenerative disorders of the lumbar spine were treated with pedicle screw fixation before 1997. They were 70 to 85 years at screw fixation (mean, 74.1 years). The postoperative follow-up period was 3 to 18 years (mean, 8.2 years). The number of fused levels by pedicle screw fixation was 1 to 7 (mean, 2.1), and bone grafting was performed in 19 patients who underwent posterolateral lumbar fusion with posterior lumbar interbody fusion and in 62 (76.5%) who underwent posterolateral lumbar fusion alone. Bone union was radiographically observed in 90.1%. The grade of independence (Independence [Bedridden] Criteria of the Daily Life of the Impaired Elderly) had been rank J (life independence) in all patients 1 year preoperatively, but deteriorated to rank A1 (capable of going out with a helper) in 51.8% of patients and rank B1 (using a wheelchair) in 19.8% immediately preoperatively. The grade of independence was rank J in 85.6% of patients 3 years postoperatively and remained rank J in 40 (87.0%) of the 46 who were alive 10 years postoperatively. Few complications associated with surgical invasion were found, and the grade of independence tended to remain at a high level for 10 years postoperatively.

Pedicle screw fixation is routinely used for spinal fusion in elderly patients. It is effective for multiple-level fusions and correction of deformities, but whether it should be applied to elderly patients with degenerative lumbar disorders is controversial due to problems such as general complications, surgical invasion, osteoporosis, and cost performance.^1-8

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This article reports the usefulness of pedicle screw fixation in elderly patients on the basis of the outcomes of spinal fusion using pedicle screw fixation in patients ≥ 70 years with degenerative lumbar disorders.

Materials and Methods

The study group comprised 81 patients 70 to 85 years (mean, 74.1 years) at surgery with degenerative lumbar disorders. The postoperative follow-up period was 3 to 18 years (mean, 8.2 years), excluding 3 patients who died within 1 year postoperatively. The percentages of patients who could be followed up 3 and 10 years postoperatively, including those who were confirmed to have died, were 100% and 77.9%, respectively.

Degenerative spondylolisthesis existed in 26 patients, spondylosis with instability in 32, spondylolytic spondylolisthesis in 7, and failed back in 16. Spinal fusion was performed by posterolateral lumbar fusion with posterior lumbar interbody fusion in 19 patients and by posterolateral lumbar fusion alone in 62 (76.5%). The number of fused levels was 1 to 7 (mean, 2.1). The implants used were VSP (Acromed, Cleveland, Ohio) in 9, Diapason (Stryker, Kalamazoo, Michigan) in 61, and others in 11.

Indications of spinal fusion with pedicle screw fixation for degenerative lumbar disease were similar to those in young to middle-aged patients, and whether the procedure should be performed was decided according to abnormal mobility observed by imaging and the extent of removal of the zygapophyseal joints, but not according to age. The indications of spinal fusion with pedicle screw fixation based on radiographic instability were as follows: 1) ≥3 mm slippage on the lateral view, 2) ≥2 mm translation from flexion to extension, 3) ≥5° abnormal tilting movement of posterior dilation in flexion, 4) localized lateral slip on the anteroposterior (AP) view, and 5) lateral tilting on the AP view.⁹

Concerning the surgical procedure of the posterolateral lumbar fusion, partial laminectomy by leaving the cephalic yellow ligament was performed with medial facetectomy for more sufficient lateral decompression. In situ fusion without reduction using pedicle screw fixation and fusion of all decompressed levels were performed, in principle.

Indications of the posterior lumbar interbody fusion were marked abnormal mobility, such as ≥10° abnormal tilting movement of the disk in flexion. Reduction using the posterior lumbar interbody fusion technique was often performed for deformities such as kyphosis and lateral tilting.⁹

Patients were placed in the lateral decubitus position with assistance immediately postoperatively and allowed to sit up and start walking after 2 to 3 days. A soft corset was often applied for 3 to 6 months postoperatively.

The clinical outcomes were assessed according to the score determined by the Japanese Orthopedic Association Scoring System for the Assessment of Treatment for Low Back Pain (JOA score).¹⁰ The grade of independence for activities of daily living was evaluated using the Independence (Bedridden) Criteria of the Daily Life of the Impaired Elderly (Table).¹¹

Results

The mean operation time was 2 hours and 48 minutes. Mean blood loss was 420 mL (125-865 mL), and 9 patients (11.1%) required homologous transfusion.

Among early postoperative complications and accidents, death within 1 year postoperatively was observed in 3 patients (3.7%); 2 died due to pulmonary embolism and 1 of an unknown cause. Postoperative delirium was noted in 11 patients (13.5%), cerebrospinal fluid leakage in 4, and radiculopathy due to pedicle screw fixation (reoperated) in 1.

Among late complications, instrumentation failure such as back-out of the screw occurred in 6 patients (7.4%), requiring reoperation in 2. Symptomatic adjacent disk problems were observed in 15 patients (18.5%), and 4 underwent reoperation. Compression fracture of adjacent or at the end of the fused level was noted in 10 patients (12.3%). There was no infection during the follow-up period.

As for other operations or complications related to lower limb function observed during the follow-up period, cervical myelopathy was noted in 4 patients, lower limb fracture in 1, artificial joint replacement in 8, and cerebral infarction in 1.

Bone union was evaluated according to the intervertebral range of motion (union, <1°; nonunion,≥1°), and when there were changes of the size in intervertebral disk vacuum phenomena, which were with degenerative disk or secondary to vertebral collapse, 12 judgments were nonunion. As a result, the bone union rate was 91%.

As for clinical outcome, JOA scores ranged from a mean of 14.2 preoperatively to 23.9 at final follow-up, which was relatively good.

The grades of independence are as follows: rank J1, uses public transportation; rank J2, only goes out near the neighborhood; rank A1, goes out with assistance; and rank A2, seldom goes out.

One year preoperatively, 61 patients (75.3%) were rank J1, and 20 (24.7%) were rank J2. Immediately preoperatively, 43 (53.1%) were rank A1, and 15 (18.5%) were rank A2. Three years postoperatively, 67 (82.7%) restored a rank J2 or higher (Figures 1, 2).

Ten years postoperatively, 63 patients were followed up (follow-up rate, 77.8%). Eleven died during those 10 years. Fifty-two survived, and of those, 46 (88.5%) retained a rank J2 or higher.

Figure 1: Myelographs of a 74-year-old man reveal complete block at the L4-L5 disk level and waist-like stenosis at the L3-L4 disk level (A, B). Independence rank J1 one year preoperatively dropped to rank A1. He returned to rank J1 immediately postoperatively (C, D). Ten years postoperatively, at 84 years, he was rank J1 (E, F). Figure 2: Changes of independence (bedridden) criteria of the daily life of the impaired elderly. Figure 3: Changes in lifestyle of patients who lived alone in their own house.

Of the 81 total patients, 20 lived alone in their own house. Ten (50%) lived alone in their own house 3 years postoperatively, and, while 3 died thereafter, 8 (47.1%) of the surviving 17 still lived alone in their own house 10 years postoperatively (Figure 3).

At 10-year follow-up, 11 had died, including 3 who had died within 1 year postoperatively. The causes of death, except in the previous 3 patients, were cancer in 4, heart disease in 2, and pneumonia in 2. They died at the ages of ≥ 80 years, with a mean of 85.8 years after a mean postoperative period of 7.9 years.

Discussion

Conventionally, lumbar canal stenosis was treated by minimally invasive surgery, giving priority to a selective decompression procedure. However, according to our survey in 1993, the therapeutic results in 40 patients with abnormal mobility (instability) on the radiographs treated by decompression procedures were unsatisfactory, being fair or poor in 26 patients (65%). In addition, 85% of the patients with unsatisfactory results were ≥ 70 years.² Since then, we have maintained the principle of performing spinal fusion depending on the severity of abnormal mobility on the radiographs even in elderly patients.

However, considering the mean life expectancy of Japan, existing medical complications, and surgical invasion, a decompression procedure alone is practical for patients ≥ 70 years.^3-6 It has been suggested that the grade of invasion and complications be suppressed to obtain the maximum effect of treatment. However, spinal fusion with pedicle screw fixation was criticized because of an increase in the invasiveness of treatment compared with decompression alone. In some patients, the satisfaction of decompression alone was the goal of treatment, but it is also known that decompression alone has limits of functional improvement.⁵

The indication of spinal fusion with pedicle screw fixation for the elderly has also expanded, and approximately 60% of fusions were indicated for degenerative lumbar disease.⁷ Reports of the effectiveness of spinal fusion with pedicle screw fixation for selected patients have increased.⁸

The mean life expectancy of Japanese people was 85.5 years for women and 78.6 years for men in 2005, one of the world's highest. The patients in this study showed a high level of independence 1 year preoperatively, suggesting that surgery was performed selectively.

In Japan, which now supports a rapidly aging society, simply living a long time is undesirable, and the period in which a person can live a healthy and independent life (ie, healthy life span) has become a major social concern. The healthy life span of the Japanese was reported to be 75 years in 2002. How to prolong this period in future aged societies is a critical issue.

In this study, no major complications or perioperative death was noted. The results of this study were satisfactory, although an adequate comparison with other series was impossible because of the absence of reports on long-term outcomes of spinal fusion using pedicle screw fixation in patients ≥ 70 years. The procedure was useful for maintaining the grade of independence for activities of daily living, at least in selected patients.

References

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Authors

Drs Tokuhashi, Ajiro, and Umezawa are from the Department of Orthopedic Surgery, Nihon University School of Medicine, Tokyo, Japan.

Drs Tokuhashi, Ajiro, and Umezawa have no relevant financial relationships to dislcose.

Correspondence should be addressed to: Yasuaki Tokuhashi, MD, Department of Orthopedic Surgery, Nihon University School of Medicine, 30-1 Oyaguchi-kamimachi, Itabashi-ku, Tokyo, 173-8610, Japan.