Jason A. Smith

Lumbar motion segment pathology adjacent to thoracolumbar, lumbar, and lumbosacral fusions.

Study Design Fifty‐eight patients came to two spinal surgeons with abnormalities adjacent to a previously fused thoracic or lumbosacral segment after they had been asymptomatic for more than 2 years. Radiographs, outcome analysis, analog pain evaluation, patient demographics, and medical indices were analyzed to evaluate risk factors for adjacent segment abnormality. Objectives Risk factors for adjacent segment breakdown and pathophysiology of adjacent segment breakdown were analyzed in this longitudinal study. Summary of Background Data Fifty‐eight patients underwent a thoracolumbar, lumbar, or lumbosacral fusion with an average symptom‐free period of 13.1 years before presentation with severe symptomatology necessitating further surgery at the adjacent segment. Methods Fifty‐eight patients with adjacent segment abnormality were analyzed by outcome assessment questionnaire, pain analog evaluation, radiographic studies, demographic factors, and sequential follow‐up evaluation. Thirty‐seven of these patients have been followed for more than 2 years after their adjacent segment surgery. Results Fifty‐eight patients developed spinal stenosis, disc herniation, or instability at a segment adjacent to a previously asymptomatic fusion that was done an average of 13.1 years earlier. Segments adjacent to the adjacent segment itself were as likely to breakdown (58%). Thirty‐seven patients were followed for more than 2 years, having outcomes defined as good or excellent in 70.3%. Seven of the 37 patients required an additional surgical procedure. Sagittal and coronal imbalances appeared to play a role in breakdown, although statistical significance was not evident. Conclusions This represents the largest series of adjacent segment breakdowns reported in the literature. The segment adjacent to the adjacent segment was almost as likely to breakdown. Sagittal and coronal alignment appeared to play a role in adjacent abnormality. Good outcomes are evident in 70% of cases.

Outcome and Complications of Long Fusions to the Sacrum in Adult Spine Deformity : Luque-Galveston, Combined Iliac and Sacral Screws, and Sacral Fixation

Study Design. A retrospective study of adults with long fusion to the sacrum using three different fixations was performed. Objective. To compare the long-term clinical results and complications associated with three methods of lumbosacral fixation for adult spine deformities: Luque-Galveston, combined iliac and sacral screws, and sacral screws. Summary of Background Data. The preferred technique for long fusion to the sacrum is controversial, and surgery for adult deformity is fraught with significant technical difficulties and high complication rates. No clinical study compares the long-term outcome of long fusion to the sacrum using these different methods of lumbosacral fixation. Methods. This study included 54 consecutive patients who underwent elective combined anterior and posterior surgical reconstruction for adult spine deformity with a minimum follow-up period of 2 years. The patients were divided into three groups on the basis of the surgical method used for the posterior spine instrumentation. Group 1 consisted of 11 patients with smooth L-rod and segmental sublaminar wire instrumentation (Luque-Galveston technique). Group 2 consisted of 36 patients with posterior Isola segmental instrumentation and combined iliac and sacral screws. Group 3 consisted of 12 patients with Isola segmental instrumentation using bicortical sacral screws. Five patients were revised to another fixation group, giving a total of 59 cases. Radiographic, clinical results, and long-term outcome data were obtained using the modified Scoliosis Research Society (SRS) outcome instrument. Results. There were 26 late complications. Pseudarthrosis developed in 10 patients, requiring revision surgery: 4 (36%) in the Group 1, 5 (14%) in Group 2, and 1 (8.5%) in Group 3. Comparison of the modified SRS outcomes showed no difference among the groups. The average SRS grand total score was 73.4% for Group 1, 70.9% for Group 2, and 62.6% for Group 3. Overall, 76% of the patients were satisfied with their outcome. The presence of perioperative complications or pseudarthrosis significantly correlated with a lower satisfaction score (P = 0.012 and P = 0.048, respectively). Sagittal plane decompensation significantly correlated with a higher pain score (P = 0.035). Patients with prior surgeries scored lower on the self-image questions than patients with no prior surgery (P = 0.007). Conclusions. Attention to sagittal balance is critical in these patients. Revision surgery is as safe and effective as primary surgery. According to the current findings, the Luque-Galveston fixation technique has an unacceptably high rate of pseudarthrosis, and this method is not recommended for adult deformities. Currently, the authors are using bicortical and triangulated sacral screws with an anterior interbody support in patients with good bone stock, but only when the spine balance is restored. Otherwise, they recommend using iliac fixation, although there is a higher rate of painful hardware, requiring removal.

Management of Fixed Sagittal Plane Deformity : Results of the Transpedicular Wedge Resection Osteotomy

Study Design. Retrospective review of a consecutive clinical series. Objectives. To evaluate the efficacy of the transpedicular wedge resection osteotomy as a technique for correction of sagittal and coronal deformity and to assess the clinical value of the procedure as assessed by patient satisfaction. Summary of Background Data. The transpedicular wedge resection osteotomy is a well-established procedure for management of fixed sagittal deformity in ankylosing spondylitis. The utility of the procedure for applications in fixed deformity other than ankylosing spondylitis has not been demonstrated, and the efficacy of the procedure in the correction of coronal deformity has not been reported. Methods. A total of 13 consecutive cases undergoing transpedicular wedge resection osteotomy for the management of sagittal deformity of any etiology were reviewed. Radiographic studies, complications, and satisfaction assessment using the modified Scoliosis Research Society instrument were the outcome parameters measured. Results. Etiologies of deformity included postsurgical, ankylosing spondylitis, idiopathic, and infectious. Measurement of C7 sagittal plumb line to sacrum improved 63% at the most recent follow-up. Lumbar lordosis increased from −15.5° to −45.4°. Coronal balance was improved in all patients who had preoperative imbalance, with an average improvement of 60% maintained at follow-up. Patient satisfaction was high in all patients and not dependent on the etiology of deformity. Conclusions. The transpedicular wedge resection osteotomy is an effective procedure for the management of fixed sagittal deformity and is generalizable for multiple etiologies. Simultaneous correction of coronal deformity is possible. The clinical value of the procedure is demonstrated in high rates of patient satisfaction.

Acute biomechanical and histological effects of intradiscal electrothermal therapy on human lumbar discs

Study Design. Human cadaver lumbar spines were used to assess the acute effects of intradiscal electrothermal therapy in vitro. Objective. To determine whether intradiscal electrothermal therapy produces acute changes in disc histology and motion segment stability. Summary of Background Data. Intradiscal electrothermal therapy has been introduced as an alternative for the treatment of discogenic low back pain. Several hypothesized mechanisms for the effect of intradiscal electrothermal therapy have been suggested including shrinkage of the nucleus or sealing of the anulus fibrosus by contraction of collagen fibers, and thermal ablation of sensitive nerve fibers in the outer anulus. Methods. Intradiscal electrothermal therapy was performed with the Spinecath by Oratec on 19 fresh, frozen human lumbar cadaver specimens. In a separate study, eight specimens were tested biomechanically and instrumented to map the thermal distribution, whereas five specimens were tested only biomechanically, both before and after intradiscal electrothermal therapy. Six additional specimens were heated with intradiscal electrothermal therapy, and the resulting canal was backfilled with a silicone rubber compound to allow colocalization of the catheter and anular architecture. Results. A consistent pattern of increased motion and decreased stiffness was observed. For the specimens in which only biomechanical measurements were taken, a 10% increase in the motion, on the average, at 5 Nm torque was observed after intradiscal electrothermal therapy. No apparent alteration of the anular architecture was observed around the catheter site in the intradiscal electrothermal therapy–treated discs. Conclusion. The data from this study suggest that the temperatures developed during intradiscal electrothermal therapy are insufficient to alter collagen architecture or stiffen the treated motion segment acutely.

Clinical outcome of trans-sacral interbody fusion after partial reduction for high-grade l5-s1 spondylolisthesis.

Study Design. A clinical retrospective study was conducted. Objective. To evaluate the clinical and radiographic outcome of reduction followed by trans-sacral interbody fusion for high-grade spondylolisthesis. Summary of Background Data. In situ posterior interbody fusion with fibula allograft has improved the fusion rates for patients with high-grade spondylolisthesis. The use of this technique in conjunction with partial reduction has not been reported. Methods. Nine consecutive patients underwent treatment of high-grade (Grade 3 or 4) spondylolisthesis with partial reduction followed by posterior interbody fusion using cortical allograft. The average age at the time of surgery was 27 years (range, 8–51 years), and the average follow-up period was 43 months (range, 24–72 months). Before surgery, eight patients had low back pain, seven patients had radiating leg pain, and five patients had hamstring tightness. The average grade of spondylolisthesis by Meyerding grading was 3.9 (range, 3–5). Charts and radiographs were evaluated, and outcomes were collected by use of the modified SRS outcomes instrument. Results. Radiographic indexes demonstrated significant improvement with partial reduction and fusion. The slip angle, as measured from the inferior endplate of L5, improved from 41.2° (range, 24–82°) before surgery to 21° (range, 5–40°) after surgery. All the patients were extremely or somewhat satisfied with surgery. The two patients who underwent this operation without initial instrumentation experienced fractures of their interbody grafts. Both of these patients underwent repair of the pseudarthrosis with placement of trans-sacral pedicle screw instrumentation and subsequent fusion. Conclusions. Partial reduction followed by posterior interbody fusion is an effective technique for the management of high-grade spondylolisthesis in pediatric and adult patient populations, as assessed by radiographic and clinical criteria. Pedicle screw instrumentation with the sacral screws capturing L5 is recommended when this technique is used for the treatment of high-grade spondylolisthesis. According to the clinical and radiographic results from this study, partial reduction and posterior fibula interbody fusion supplemented with pedicle screw instrumentation is an effective technique for select patients with high-grade spondylolisthesis at L5–S1.

Reoperation after primary fusion for adult spinal deformity: rate, reason, and timing.

Study Design. Retrospective cohort study of consecutive patients undergoing primary fusion with segmental fixation for adult spinal deformity. Obejctive. We sought to determine the survivorship of primary fusion for adult spinal deformity and identify patient-specific predictors of complications requiring reoperation. Summary of Background Data. Compared with the adolescent population, surgery for adult deformity is often more complex and technically difficult, contributing to a high reported rate of complications that can result in the need for reoperation. Reported complication rates vary widely. Methods. From 1999–2004 all patients who underwent primary instrumented fusion for nonparalytic adult spinal deformity at a single center were included. Inclusion criteria included minimum age at surgery of 20 years and minimum fusion length of 4 motion segments. Surgical, demographic, and comorbidity data were recorded. Reoperation was defined as any additional surgery involving levels of the spine operated on during the index procedure and/or adjacent levels. Comparisons were performed between patients who required reoperation and those who did not. Results. Eighty-nine patients met inclusion criteria. Endpoint (minimum 2 years follow-up or reoperation) was reached for 91%. Mean follow-up was 3.8 years. Cumulative reoperation rate was 25.8%. Survival was 86.4% at 1 year, 77.2% at 2 years, and 75.2% at 3 years. Reasons for reoperation included infection (n = 8), pseudarthrosis (n = 3), adjacent segment problems (n = 5), implant failure (n = 4), and removal of painful implants (n = 3). Multivariate analysis showed smoking was significantly higher in the reoperation group. Conclusion. Using a strict definition of reoperation for a well-defined cohort, in the presence of relevant risk factors, many patients undergoing primary fusion for adult spinal deformity required reoperation. The results indicate that complex medical and surgical factors contribute to the treatment challenges posed by patients with adult spinal deformity. This represents the largest cohort reported to date of patients undergoing primary fusion using third-generation instrumentation techniques.

Management of Fixed Sagittal Plane Deformity : Outcome of Combined Anterior and Posterior Surgery

Study Design. Retrospective study of consecutive patient series. Objectives. To review the radiographic and clinical results of patients with preoperative fixed sagittal imbalance treated with combined anterior and posterior arthrodesis, and to determine factors that predict clinical outcome. Summary of Background Data. Combined anterior and posterior arthrodesis of the spine is useful in the management of fixed deformity involving the coronal and sagittal planes. The specific indications for combined surgery in the patient with regional and global imbalance have not been well defined. Methods. Retrospective review of 25 consecutive patients treated with combined anterior and posterior spinal arthrodesis. Inclusion criteria included a preoperative global sagittal imbalance of at least 5 cm. Outcome variables included radiographic measures of preoperative, postoperative, and follow-up films, and a clinical assessment using the Modified SRS Outcomes Instrument and a review of postoperative complications. Results. Twenty-five consecutive cases were reviewed. Mean age was 58 years (range 38–77), and mean follow-up was 55 months (range 24–81) for clinical and 44.5 (range 24–81) months for radiographic outcome variables. The mean preoperative sagittal imbalance was 10.5 cm (range 5.2–23.3), which improved to 2.9 cm (range 0–12.6) after surgery, and was maintained as 3.3 cm (range 0–13.5) at follow-up. Mean lumbar lordosis was −23° (range +40 to −47) before surgery, and increased to −42° at follow-up (range −20° to −60°), an increase of 19°. Patients with preoperative regional hypolordosis in the lumbar spine that was corrected surgically had the highest postoperative scores. The mean score for patient satisfaction with surgical management was 4.45 (range 2.5–5). Correlation analysis of clinical outcome domains demonstrated that patient satisfaction correlated poorly with domains of pain (r = 0.37, P = 0.1) and function (r = 0.4, P = 0.09). Within the domains, self-image showed highest correlation with patient satisfaction (r = 0.65, P = 0.006) and total score (r = 0.89, P = 0.0001). Conclusions. Patients with global sagittal imbalance of the spine were effectively treated with a combined anterior and posterior arthrodesis as measured by radiographic parameters. Patient satisfaction with surgery, and overall clinical outcomes were best in cases that resulted in an increase in lumbar lordosis. The subset of patients with preoperative regional hypolordosis of the lumbar spine has better outcomes than those with preoperative lumbar lordosis in the physiologic range.

Temperature and Thermal Dose Distributions During Intradiscal Electrothermal Therapy in the Cadaveric Lumbar Spine

Study Design. Human cadaveric lumbar spines were used to assess the temperature and thermal dose distribution during intradiscal electrothermal therapy in vitro. Objectives. To determine whether intradiscal electrothermal therapy produces adequate tissue temperatures to denature annular collagen or ablate nerve cells. Summary of Background Data. Several hypothesized mechanisms for the effect of intradiscal electrothermal therapy have been suggested and include: 1) shrinkage of the nucleus and/or the annulus fibrosus by contraction of collagen fibers; and 2) thermal ablation of sensitive nerve fibers in the outer annulus. Methods. Intradiscal electrothermal therapy was performed using the standard clinical protocol on 12 lumbar specimens in a 37.0°C water bath using the SpineCath® by Oratec. Temperatures were recorded simultaneously at 40 different locations in the disc. Thermal dose (Equivalent Minutes 43.0°C) was calculated at each temperature point. Results. The highest temperature measured (out of 520 points) was 64.0°C and was within 1 mm of the heating coil. Temperatures in excess of 60°C were all within 1 to 2 mm of the intradiscal electrothermal therapy catheter surface, the 50 to 60°C range extended ∼6 mm, above 48°C extended ∼7 mm, and above 45°C extended to ∼10 mm. Less than 2% of points achieved temperatures sufficient for collagen denaturation (>60°C). On average, 42.5% of points accumulated >250 Equivalent Minutes 43.0°C, a conservative common dose threshold for thermal necrosis of cells. The time history of thermal measurements demonstrated that the disc temperature had not reached steady state by the end of the heating protocol (16.5 minutes). Conclusions. Except for a very limited margin (1–2 mm) around the catheter, the temperature necessary to induce collagen shrinkage was not observed within the disc. Temperatures sufficient to ablate nerves were developed in some areas but were not reliably produced in clinically relevant regions, such as the posterior annulus. These results suggest that beneficial clinical outcomes may be critically dependent on probe placement or other factors unknown.

Does instrumented anterior scoliosis surgery lead to kyphosis, pseudarthrosis, or inadequate correction in adults?

Study Design. Retrospective review of cases in which a single solid rod was used for the anterior correction of thoracolumbar and lumbar idiopathic scoliosis in adults. Objectives. To evaluate the efficacy and outcomes in these patients. Summary of Background Data. Anterior spinal fusion with instrumentation has been found to be kyphogenic in the treatment of scoliosis. Recent reports have shown an extremely high rate of pseudarthrosis and implant failure even in adolescents who have undergone anterior spinal fusion with a single flexible or rigid rod. Methods. Fifteen consecutive adult patients with (average age, 37.5 years) had undergone anterior spinal fusion with a rigid rod were included in this study. One was lost to follow-up, leaving 14 patients with a complete radiographic follow-up of 44 months and clinical follow-up of 61 months. Patients were sent the Modified Scoliosis Research Society (SRS) Outcomes Instrument, charts were reviewed, and preoperative, postoperative, and final follow-up films of the entire spine were evaluated by independent reviewers uninvolved in the care of the patients. Results. The average preoperative major curve was 50°, which improved to 16° at follow-up (a 66% correction). The average correction of the upper compensatory curve and lower fractional curve were 40% and 61%, respectively. The thoracolumbar sagittal plane alignment was maintained or improved in all patients (i.e., this surgery did not induce kyphosis in any patient). On average 0.9 levels were “saved” compared with levels chosen by the authors for posterior surgery. All patients achieved a solid fusion. Follow-up Modified SRS questionnaires revealed a satisfaction score 4.5 out of a possible score of 5, a pain score of 4.1 out of 5, a self-image score of 4.1 out of 5, a function score of 4.1 out of 5, and a mental health score of 4.0 out of 5, with an overall score of 82%. All patients but one were satisfied or extremely satisfied with the results of surgery. There was no incidence of implant breakage. Conclusions. The results of anterior spinal fusion using a single solid rod in adults with idiopathic scoliosis in this series are excellent, with 100% fusion rate, no development of kyphosis, and no incidence of hardware failure.

Biomechanics of cervical laminoplasty: kinetic studies comparing different surgical techniques, temporal effects and the degree of level involvement

Laminoplasty is a common surgical technique used to treat cervical myelopathy. Both voids and contradictory information exist in the literature with regard to the initial and long-term biomechanical consequences of cervical laminoplasty. In order to clarify the existing literature, as well as provide clinically useful information, we identified three specific aims: (1) to measure the long-term differences in kinetics between the open door laminoplasty (ODL) and French door laminoplasty (FDL) techniques; (2) to delineate differences in primary and long-term cervical motion after laminoplasty; and (3) to determine whether inclusion of additional levels in the laminoplasty procedure results in a change in immediate cervical biomechanics. The study design involved both an animal (caprine) model and in vitro surgical simulation. We kinematically evaluated the cervical spine specimens (C2–C7) by applying pure bending moment loads to the cephalad vertebra (C2), while constraining the caudal vertebra (C7). Resultant intervertebral rotations (C3–C6) were determined via stereophotogrammetry. Overall, the data indicate that both FDL and ODL significantly reduce range of motion 6 months postoperatively, compared with the un-operated spine. There were no significant differences between the two techniques after 6 months. We also showed that ODL produces a significant reduction in motion 6 months postoperatively compared with the immediate postoperative condition. Finally, the data indicated that extending the laminoplasty from two to four levels did not significantly change range of motion. The choice of technique should be based upon the surgeon’s experience with these technically demanding procedures. In addition, initial stability considerations should not affect the decision to extend the laminoplasty to adjacent levels. Finally, the data also suggest that early changes in biomechanics should not be a major factor when considering whether immobilization of the cervical spine is necessary after laminoplasty. In fact, our temporal study, as well as previously reported clinical data, indicates that one should expect significantly decreased intervertebral motion 6 months after laminoplasty. Therefore, early physical therapy should be considered to preserve a more physiologic pattern of cervical range of motion.