Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004
Robert F. Heary
✓ Spinal deformity is a complex and dynamic process that occurs in both the sagittal and coronal planes of the thoracolumbar spine. Successful treatment is aimed at achieving satisfactory balance in both of these planes. The spinal curvatures in the adult differ greatly from those in adolescents. As a general rule the adult curves tend to be stiffer, whereas adolescent curves are more flexible. In addition to cosmetic concerns, adult patients frequently present with pain and neurological symptoms in contrast to adolescents who usually do not experience this degree of pain or neurological symptoms. The treatment of adult spinal deformity differs substantially from that of adolescent deformity. Surgeries in the former tend to be more complex procedures associated with higher rates of intra- and perioperative complications. The goals of surgery in the adult are to obtain a solid fusion with a balanced spine, to relieve pain, and to prevent further deformity. A secondary goal is to correct the curve, and, in so doing, to improve the cosmetic appearance. In this review the author addresses the basic principles of spinal corrective surgery in the adult and provides insight into the varied treatment options available.
Robert F. Heary
Robert F. Heary
Robert F. Heary and Christopher M. Bono
Metastatic spinal tumors are the most common type of malignant lesions of the spine. Prompt diagnosis and identification of the primary malignancy is crucial to overall treatment. Numerous factors affect outcome including the nature of the primary cancer, the number of lesions, the presence of distant nonskeletal metastases, and the presence and/or severity of spinal cord compression. Initial management consists of chemotherapy, external beam radiotherapy, and external orthoses. Surgical intervention must be carefully considered in each case. Patients expected to live longer than 12 weeks should be considered as candidates for surgery. Indications for surgery include intractable pain, spinal cord compression, and the need for stabilization of impending pathological fractures. Whereas various surgical approaches have been advocated, anterior-approach surgery is the most accepted procedure for spinal cord decompression. Posterior approaches have also been used with success, but they require longer-length fusion. To obtain a stable fixation, the placement of instrumentation, in conjunction with judicious use of polymethylmethacrylate augmentation, is crucial. Preoperative embolization should be considered in patients with extremely vascular tumors such as renal cell carcinoma. Vertebroplasty, a newly described procedure in which the metastatic spinal lesions are treated via a percutaneous approach, may be indicated in selected cases of intractable pain caused by non- or minimally fractured vertebrae.
Robert F. Heary and Reza J. Karimi
The authors describe a surgical technique for the correction of symptomatic degenerative lumbar scoliosis. Using a single, unilateral, interbody cage placed on the concave side of the coronal deformity, combined with a dorsal decompression and instrumented posterolateral fusion, this technique has resulted in excellent curve correction, fusion results, and clinical outcomes in a series of 4 patients. Each of these patients presented with intractable, axial low-back pain and symptomatic unilateral nerve root compression on the concave side of a lumbar scoliotic deformity. The management is described in detail.
Robert F. Heary and Christopher M. Bono
There are many options for the surgical treatment of lumbar spondylolisthesis, including anterior and posterior techniques. Among the most versatile is a 360° fusion. In consideration of the added risk of morbidity of two procedures, circumferential fusion leads to the highest fusion rates. This is particularly useful for patients at high risk for pseudarthrosis, such as patients with diabetes, posttransplant recipients, and those in whom fusion procedures have failed. Likewise, a 360° fusion may also be useful in achieving fusion in biomechanically disadvantageous situations, such as at the L5–S1 level or with high-grade subluxation. The options for 360° fusion are many and are determined, among other factors, by surgical pathology and surgeon preference. Standard open techniques are still considered the gold standard, although newer less invasive methods of circumferential fusion are being used more frequently. The operating surgeon must have a thorough knowledge of all available maneuvers for critical and effective decision making.
Daipayan Guha, Robert F. Heary and Mohammed F. Shamji
Decompression without fusion for degenerative lumbar stenosis is an effective treatment for both the pain and disability of neurogenic claudication. Iatrogenic instability following decompression may require further intervention to stabilize the spine. The authors review the incidence of postsurgical instability following lumbar decompression, and assess the impact of surgical technique as well as study design on the incidence of instability.
A comprehensive literature search was performed to identify surgical cohorts of patients with degenerative lumbar stenosis, with and without preexisting spondylolisthesis, who were treated with laminectomy or minimally invasive decompression without fusion. Data on patient characteristics, surgical indications and techniques, clinical and radiographic outcomes, and reoperation rates were collected and analyzed.
A systematic review of 24 studies involving 2496 patients was performed, assessing both open laminectomy and minimally invasive bilateral canal enlargement. Postoperative pain and functional outcomes were similar across the various studies, and postoperative radiographie instability was seen in 5.5% of patients. Instability was seen more frequently in patients with preexisting spondylolisthesis (12.6%) and in those treated with open laminectomy (12%). Reoperation for instability was required in 1.8% of all patients, and was higher for patients with preoperative spondylolisthesis (9.3%) and for those treated with open laminectomy (4.1%).
Instability following lumbar decompression is a common occurrence. This is particularly true if decompression alone is selected as a surgical approach in patients with established spondylolisthesis. This complication may occur less commonly with the use of minimally invasive techniques; however, larger prospective cohort studies are necessary to more thoroughly explore these findings.
Robert F. Heary, Christopher M. Bono and Margaret Black
Object. The authors evaluated the accuracy of placement of thoracic pedicle screws by performing postoperative computerized tomography (CT) scanning. A grading system is presented by which screw placement is classified in relation to neurological, bone, and intrathoracic landmarks.
Methods. One hundred eighty-five thoracic pedicle screws were implanted in 27 patients with the assistance of computer image guidance or fluoroscopy. Postoperative CT scanning was conducted to determine a grade for each screw: Grade I, entirely contained within pedicle; Grade II, violates lateral pedicle but screw tip entirely contained within the vertebral body (VB); Grade III, tip penetrates anterior or lateral VB; Grade IV, breaches medial or inferior pedicle; and Grade V, violates pedicle or VB and endangers spinal cord, nerve root, or great vessels and requires immediate revision. Based on anatomical morphometry, the spine was subdivided into upper (T1–2), middle (T3–6), and lower (T7–12) regions. Statistical analyses were performed to compare regions. The mean follow-up period was 37.6 months.
The following postoperative CT scanning—documented grades were determined: Grade I, 160 screws (86.5%); Grade II, 15 (8.1%); Grade III, six (3.2%); Grade IV, three (1.6%); and Grade V, one (0.5%). Among cases involving screw misplacements, Grade II placement was most common, and this occurred most frequently in the middle thoracic region.
Conclusions. The authors' grading system has advantages over those previously described; however, further study to determine its reliability, reproducibility, and predictive value of clinical sequelae is warranted. Postoperative CT scanning should be considered the gold standard for evaluating thoracic pedicle screw placement.