John E. Lonstein

The surgical and medical perioperative complications of anterior spinal fusion surgery in the thoracic and lumbar spine in adults. A review of 1223 procedures.

Study Design A retrospective review of 1223 thoracic and lumbar anterior spinal fusions was performed from 1969 through 1992. Objectives To document the incidence and specific types of perspective complications related to anterior spinal fusions. Summary of Background Data Despite the increased use of anterior spinal surgery, there has been little documentation of the specific types and frequencies of the complications associated with its use. Methods All Minnesota Spine Center patients age 18 years or older who had anterior spinal fusions between the levels of T1 and S1 from August 1969 to June 1992 were reviewed for the occurrence of perioperative complications. Surgical approach and technique and associated comorbidity was recorded. Results The risk of a complication was increased for patients over age 60 years, for women, and for patients with multiple preexisting health problems. Serious complications, such as death (0.3%), paraplegia (0.2%), and deep wound infection (0.6%) were rare. The complication rate for complications that were directly attributed to the anterior spinal surgery was 11.5%. Conclusions Anterior spinal fusion surgery is a safe procedure and can be used with confidence when the nature of a patients spinal disorder dictates its use. Complications are often approach specific.

Breast cancer mortality after diagnostic radiography : Findings from the U.S. Scoliosis Cohort Study

Study Design. A retrospective cohort study was conducted in 5573 female patients with scoliosis who were referred for treatment at 14 orthopedic medical centers in the United States. Patients were less than 20 years of age at diagnosis which occurred between 1912 and 1965. Objectives. To evaluate patterns in breast cancer mortality among women with scoliosis, with special emphasis on risk associated with diagnostic radiograph exposures. Summary of Background Data. A pilot study of 1030 women with scoliosis revealed a nearly twofold statistically significant increased risk for incident breast cancer. Although based on only 11 cases, findings were consistent with radiation as a causative factor. Methods. Medical records were reviewed for information on personal characteristics and scoliosis history. Diagnostic radiograph exposures were tabulated based on review of radiographs, radiology reports in the medical records, radiograph jackets, and radiology log books. Radiation doses were estimated for individual examinations. The mortality rate of the cohort through January 1, 1997, was determined by using state and national vital statistics records and was compared with that of women in the general U. S. population. Results. Nearly 138,000 radiographic examinations were recorded. The average number of examinations per patient was 24.7 (range, 0–618); mean estimated cumulative radiation dose to the breast was 10.8 cGy (range, 0–170). After excluding patients with missing information, 5466 patients were included in breast cancer mortality analyses. Their mean age at diagnosis was 10.6 years and average length of follow-up was 40.1 years. There were 77 breast cancer deaths observed compared with the 45.6 deaths expected on the basis of U.S. mortality rates (standardized mortality ratio [SMR] = 1.69; 95% confidence interval [CI] = 1.3–2.1). Risk increased significantly with increasing number of radiograph exposures and with cumulative radiation dose. The unadjusted excess relative risk per Gy was 5.4 (95% CI = 1.2–14.1); when analyses were restricted to patients who had undergone at least one radiographic examination, the risk estimate was 2.7 (95% CI = −0.2–9.3). Conclusions. These data suggest that exposure to multiple diagnostic radiographic examinations during childhood and adolescence may increase the risk of breast cancer among women with scoliosis; however, potential confounding between radiation dose and severity of disease and thus with reproductive history may explain some of the increased risk observed.

Complications Associated with Pedicle Screws

BACKGROUND The safety and the effectiveness of pedicle-screw instrumentation in the spine have been questioned despite its use worldwide to enhance stabilization of the spine. This review was performed to answer questions about the technique of insertion and the nature and etiology of complications directly attributable to the screws. METHODS We performed a retrospective review of all of the pedicle-screw procedures that were done by us from January 1, 1984, to December 31, 1993. We inserted 4790 screws during 915 operative procedures on 875 patients; 668 (76.3 percent) of the patients had a lumbosacral arthrodesis. The mean duration of follow-up was three years (range, two to five years). The accuracy of screw placement was assessed on intraoperative, immediate postoperative, and follow-up radiographs with use of a technique that was developed by one of us (F. D.); this technique has yet to be validated to determine the prevalence of various types of error. RESULTS Of the 4790 screws, 4548 (94.9 percent) had been inserted within the pedicle and the vertebral body. One hundred and thirty-four (2.8 percent) of the screws had perforated the anterior cortex, and this was the most common type of perforation. One hundred and fifteen (2.4 percent) of the screws were associated with complications that could be ascribed to the use of pedicle screws. The most common problem was late-onset discomfort or pain related to a pseudarthrosis or perhaps to the screws; this problem was associated with 1102 (23.0 percent) of the screws, used in 222 (24.3 percent) of the procedures. The symptoms necessitated removal of the instrumentation with or without repair of the pseudarthrosis. A pseudarthrosis was found during forty-six (20.7 percent) of the 222 procedures. Irritation of a nerve root occurred after nine procedures (1.0 percent) and was caused by eleven screws (0.2 percent); it was more commonly caused by medially placed screws. Three patients had residual neurological weakness despite removal of the screws. Twenty-five screws (0.5 percent), used in twenty procedures (2.2 percent), broke. The screws that broke were of an early design. A pseudarthrosis was found in thirteen of twenty patients who had broken screws. Sixteen of the twenty patients had an exploration; three of them were found to have a solid fusion, and thirteen were found to have a pseudarthrosis. The remaining four patients had evidence of a solid fusion on radiographs and had no pain. CONCLUSIONS There are few problems associated with the insertion of screws, provided that the surgeon is experienced and adheres to the principles and details of the operative technique. Our review revealed a low rate of postoperative complications related to pedicle screws. The problem of late-onset pain may be related to the implants or to the stiffness of the construct; however, it is difficult to accurately identify its exact etiology.

Treatment of symptomatic flatback after spinal fusion.

Fifty-five patients who had loss of lumbar lordosis after spinal fusion and subsequently had corrective osteotomies were studied. When they were first seen, fifty-two patients (95 per cent) were unable to stand erect and forty-nine (89 per cent) had back pain. The previous use of distraction instrumentation with a hook placed at the level of the lower lumbar spine or the sacrum was the factor that was most frequently identified as leading to the development of the flatback syndrome. Sixty-six extension osteotomies were performed in these fifty-five patients. Nineteen patients (35 per cent) had an associated anterior spinal fusion. Thirty-three patients (60 per cent) had one or more complications, including pseudarthrosis, a dural tear, failure of hardware, neurapraxia, and urinary tract infection. The results of the operation were evaluated at follow-up by review of clinical records, radiographs, and questionnaires. At an average follow-up of six years (range, two to fourteen years), most patients felt that they had benefited from the corrective osteotomies. However, twenty-six patients (47 per cent) continued to lean forward and twenty patients (36 per cent) continued to have moderate or severe back pain. The failure to restore sagittal plane balance led to a higher rate of pseudarthrosis, which was associated with recurrent deformity. Anterior spinal fusion combined with posterior osteotomy resulted in greater maintenance of correction. The prevention of flatback syndrome is important, since its treatment is difficult. When a spinal fusion must be extended to the level of the lower lumbar spine or the sacrum, the use of distraction instrumentation should be avoided in order to prevent this deformity.

The Milwaukee Brace for the Treatment of Adolescent Idiopathic Scoliosis. A Review of One Thousand and Twenty Patients.

We reviewed the medical records and roentgenograms of 1020 patients who had been managed for adolescent idiopathic scoliosis, between January 1954 and December 1979, with a Milwaukee brace; we wished to determine whether use of the brace had effectively altered the natural history of the disease. The findings were considered with respect to a previous study of 727 children who had had comparable curves and had not initially been managed with the brace but had been followed for progression of the curve, during the same time-span as that in the current study. Of those 727 patients, 558 (77 percent) had no progression of the curve. The average age of the 1020 patients at the time that treatment with the brace was begun was thirteen and one-half years (range, ten to seventeen years). None of the patients had received any other treatment, and all had been managed only by the physicians participating in this study. In both the current and the earlier series, the outcome was considered a failure if the curve had increased 5 degrees or more; in the patients in the current study, who were managed with the brace, the outcome was also considered a failure if operative intervention had been needed. Of the 1020 patients in the current series, 229 (22 percent) had operative intervention; this rate was higher in the patients who had a curve of more than 30 degrees at the time of bracing and in those who had a Risser sign of 0 or 1. The 791 remaining patients, who were managed with the brace only, had a mild improvement of 1 to 4 degrees at the time that use of the brace was discontinued (the difference being within the margin of error of measurement). With respect to curves of between 20 and 39 degrees, the rate of failure was lower in the current series of patients who had been managed with the brace than in the earlier series of patients who had not been thus managed but had been followed for progression. Progression of the curve was found to be related to the pattern and magnitude of the curve; the age of the patient at the time of presentation; the Risser sign; and, in girls, the menarchal status. We recommend that immature adolescents who have a curve of more than 25 degrees and a Risser sign of 0 be managed with a brace immediately, rather than after progression has been documented.

Adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis appears during the adolescent growth spurt, a time when children are growing rapidly. In many cases the abnormal spinal curve is stable, although in some children the curve is progressive (meaning it becomes more severe over time). For unknown reasons, severe and progressive curves occur more frequently in girls than in boys. However, mild spinal curvature is equally common in girls and boys.

Hip dislocation and subluxation in cerebral palsy.

Summary: Four hundred sixty-four patients with cerebral palsy were reviewed. They were placed in four function groups: independent ambulators (n = 76), dependent ambulators (n = 43), independent sitters (n = 41), and dependent sitters (n = 304). The percentage of subluxated or dislocated hips increased from 7% for independent ambulators to 60% for dependent sitters. In the dependent sitters, a level pelvis or different degrees of pelvic obliquity did not correlate with whether the hip was located, subluxated, or dislocated. The subluxated or dislocated hip did not correlate with the high side or the amount of pelvic obliquity. Muscle imbalance around the hip and not the pelvic obliquity is the cause of the hip subluxation or dislocation.

Post-laminectomy kyphosis.

Post-laminectomy spinal deformity occurs in 50% of children undergoing laminectomies for cord tumors. Kyphosis is the most frequent deformity found. The integrity of the facet joints appears to be one of the most important factors in the development of this kyphosis. More children are surviving after treatment of these tumors and a pessimistic attitude is not warranted. Observation of a progressing deformity is not acceptable treatment. When kyphosis develops, early prompt bracing must be started. For a progressive or severe kyphosis, an anterior spine fusion is indicated. This is reinforced by a posterior fusion with Harrington instrumentation. Surgical reconstruction is indicated in children recovering from extensive laminectomies but with a good prognosis.

Spondylolisthesis in children. Cause, natural history, and management.

Spondylolysis is the term used for a defect in the pars interarticularis of the vertebra. The term is from the Greek roots spondylos, meaning vertebra, and lysis, meaning break or defect. Spondylolisthesis is from spondylos and listhesis, meaning movement or slipping, and refers to the slipping forward of one vertebra on the next caudal vertebra. Spondylolisthesis was first described in 1782 by Herbiniaux, a Belgian obstetrician. Spondylolysis is most common at L5, and therefore a slip is most common at this level, with L5 slipping forward on S1. Even though this discussion is about spondylolisthesis, some discussion of spondylolysis is necessary, because this is the cause of the most common type of spondylolisthesis.

Treatment of idiopathic scoliosis in the Milwaukee brace.

The results of treatment of idiopathic scoliosis with a Milwaukee brace were studied in 133 patients (127 girls and six boys) whose ages ranged from eight years and five months to sixteen years and two months at the beginning of treatment. These 133 patients had 192 separate curves (119 right thoracic, thirty-nine high lumbar, twelve thoracolumbar, and twenty-two high left thoracic). Of these patients, seventy-four with 109 curves were followed for five years or more after the brace was discontinued (average, eight years; range, five to thirteen years); twenty-nine patients were treated surgically because of a poor response to the brace or progression of the curve; and thirty patients were lost to follow-up. More than 80 per cent of the seventy-four patients followed for five years or more showed some increase of their curves after the brace was discontinued. The average correction at follow-up compared with the original curve was 2 degrees for thoracic curves (range, -18 to 24 degrees) and 4 degrees for the thoracolumbar and lumbar curves (range, -11 to 17 degrees). The brace was more effective for curves of less than 40 degrees. More than one-third of the patients with curves of 40 degrees or more eventually required surgical treatment. Age, curve pattern, and status of the iliac and ring epiphyses did not correlate withe response to brace treatment. The best guideline for prediction of the results of brace treatment was the response of the curve to the brace, especially during the first year of treatment. If the curve is reduced in the brace to less than 50 per cent of its initial measurement, there is a good chance of obtaining significant permanent correction.