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Vedat Deviren

Publications and source records attributed to Vedat Deviren.

14 recordsLinked to original sources
PubMed2006

The effects of rod contouring on spinal construct fatigue strength.

STUDY DESIGN: In vitro fatigue loading using a corpectomy model outfitted with posterior pedicle screw instrumentation. OBJECTIVE: The purpose of this study was to detect differences in fatigue resistance of titanium and stainless steel spinal constructs that use rods contoured using a French Bender, and to compare differences in fatigue resistance of contoured and straight titanium rods. SUMMARY OF BACKGROUND DATA: Instrumentation failure is generally thought to be caused by fatigue or cyclic loading. Intraoperative contouring of the posterior rods is almost always required to match the native kyphotic (thoracic) or lordotic (cervical or lumbar) spinal curvature. How bending these rods affects their overall fatigue resistance is not well described. In addition, changes in fatigue resistance may be a function of material type. METHODS: Spinal constructs were evaluated using the ASTM F1717-01 model. Two different titanium-based rods (Ti6AL4V and CpTi) and two different steel-based rods (Orthinox and 316L stainless steel) were evaluated in this study (n = 6 for each group). Rods were contoured at two points using a French Bender and were rigidly coupled to polyaxial pedicle screws within UHMWPE vertebral bodies. Constructs were cycled at a load ratio of 10 between a minimum and maximum loading regime of -250 N/-25 N and -700 N/-70 N at a frequency of 4 Hz. Estimated maximum nominal stresses at various points of interest in the spinal constructs were calculated using beam theory. Effects of the rod material, load, and stress on the number of cycles to failure were analyzed using Cox proportional hazards regression. RESULTS: All of the spinal constructs with contoured CpTi rods and contoured Ti6Al4V rods failed at one of the bends in the rods. Almost all of the spinal constructs with straight CpTi rods and straight Ti6Al4V rods failed where the blocker screw fastens the rod to the coupler of the polyaxial screw head. Contoured titanium constructs demonstrated significantly lower fatigue life than contoured 316L constructs. Contouring tended to lower the fatigue life of both the Ti6Al4V and CpTi constructs. CONCLUSION: Intraoperative rod contouring using a French Bender significantly reduces the fatigue life of titanium spinal constructs.

Bone Nails↗
PubMed2005

The validity of Lenke criteria for defining structural proximal thoracic curves in patients with adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective series. OBJECTIVE: To delineate the efficiency of using Lenke criteria during the decision of whether to include the proximal thoracic curve into instrumented fusion or not in patients with adolescent idiopathic scoliosis (AIS) treated with posterior translational instrumentation. SUMMARY OF BACKGROUND DATA: Lenke and colleagues classified the curves of patients with AIS and assigned the term "structural" or "nonstructural" to each curve. However, there is still not much consensus on the definition of structural proximal thoracic curve, and structurality criteria for proximal thoracic curve have not been validated yet. METHODS: Inclusion criteria were: (1) patients with AIS treated with a posterior translational instrumentation system and older than 10 years; (2) nonstructural upper thoracic curves (side bending Cobb <25 degrees and T2-T5 kyphosis <+20 degrees); and (3) a minimum of 2 years of follow-up. A total of 37 consecutive patients, including 6 males and 31 females, with AIS that was treated, with an average age of 15 years (range 11-24) and average follow-up of 55 months (range 24-90) were studied. For radiologic evaluation of the patients, preoperative, postoperative, and latest follow-up radiographs were used. There were 2 groups constructed according to the involvement of proximal thoracic curve into instrumented fusion. Group 1 included those patients who underwent uppermost extent of the instrumentation, either T2 or T3, indicating inclusion of proximal thoracic curve into instrumentation. Group 2 included individuals who underwent uppermost extent of the instrumentation at T4 or lower, indicating partial or no inclusion of the proximal thoracic curve into instrumented fusion. Radiographic evaluation included the measurement of proximal thoracic, main thoracic, and thoracolumbar-lumbar curves. On the lateral radiographs, sagittal Cobb angles of T2-T5, T5-T12, and T10-L2 were measured. Difference between right and left coracoid process heights, clavicle angle, and T1 tilt were determined for assessment of shoulder balance. RESULTS: The 2 groups were statistically equivalent in terms of age at surgery, follow-up time, preoperative proximal thoracic and main thoracic, and their corresponding side bending curve magnitudes, as well as the parameters related to shoulder balance before surgery (P > 0.05). The 2 groups were also statistically equivalent regarding immediate postoperative and latest follow-up proximal thoracic and main thoracic, and parameters related to shoulder balance (P > 0.05). CONCLUSION: It was observed that the Lenke description for structurality of proximal thoracic curves can effectively determine which curves need fusion and which curves do not. Because there was no difference among inclusion of a nonstructural proximal thoracic curve into fusion or solely fusing the main thoracic curve in terms of outcomes, extension of fusion to T2 or T3 is unnecessary. In this patient population, the question of what the upper extent of instrumentation should be could not be answered.

Adolescent↗
PubMed2005

Pedicle screw fixation of the thoracic spine: an in vitro biomechanical study on different configurations.

STUDY DESIGN: An in vitro biomechanical study of different pedicle screw configuration usage on the thoracic spine using a cadaveric model. OBJECTIVES: To investigate the degree of motion afforded different pedicle screw configurations in the thoracic spine using a cadaveric model with 2 different degrees of intrinsic stability. SUMMARY OF BACKGROUND DATA: Recently, thoracic pedicle screws have become an alternative to hook and wire fixation, and have gained popularity. Clinically, pedicle screw use has ranged from application to every segment, to skipping every other level. There exists no clear consensus as to which strategy is most appropriate. METHODS: The load-displacement behavior of 6 different constructs was determined on 8 fresh frozen cadaver spine specimens (T4-T12). Each construct was evaluated on 2 destabilization models, including minimum destabilization (bilateral facetectomy) and maximum destabilization (facetectomy and annulotomy). Pure moments were applied, and the resultant range of motion for each scenario was determined. RESULTS: Facetectomy did not significantly destabilize the thoracic spine. Annulotomy and facetectomy created gross instability that rendered testing of this destabilization model impossible. All constructs significantly reduced the range of motion compared to intact or facetectomized specimens (P < or = 0.001). When different constructs were compared to each other, a pattern of continuously increasing stability emerged, with the "maximum" construct being the most stable and "minimum" configuration being the least, with varying degrees of statistical significance. CONCLUSIONS: Our results suggest that the most important factor for the acute postoperative stability of spinal fixation is the degree of preoperative or iatrogenic destabilization. The minimum amount of pedicle screws provides adequate stability when there is minimal destabilization of the spine. On the other hand, when anterior column release has been performed or instability exists before surgery, segmental pedicle screw fixation may be necessary to achieve adequate stability.

Aged↗
PubMed2005

The effect on anterior column loading due to different vertebral augmentation techniques.

BACKGROUND: Vertebral compression fractures are a significant cause of morbidity amongst the elderly, resulting in pain, kyphosis, decreased mobility, and often depression. The two most popular operative treatments of compression wedge fractures are vertebroplasty and kyphoplasty, however, which method leads to restoration of normal spinal loading is unknown. METHODS: A cadaveric thoracolumbar spine model was fractured and then treated using one of two techniques: vertebroplasty or kyphoplasty. Three non-destructive loading regimes were applied to the intact, fractured and treated cases. Sub-adjacent nuclear pressure, used as a measure of anterior column loading, was determined for each experimental variant and loading case. FINDINGS: The data indicate that nuclear pressure was substantially reduced after the spine was fractured. These pressures were minimally increased after treatment, however, not to the level of the pre-fractured condition. In all loading cases, there were no significant differences between the two treatment types. INTERPRETATION: While our data show that both vertebroplasty and kyphoplasty allow the disc to generate higher nuclear pressures, neither treatment increased nucleus pulposus pressure above the level of the intact state. This directly relates to the clinical condition in that adjacent segment fractures sustained subsequent to either treatment is likely the result of overall disease progression, and not a direct result of the intervention.

Adult↗
PubMed2004

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.

Animals↗
PubMed2003

Studies in the modified Scoliosis Research Society Outcomes Instrument in adults: validation, reliability, and discriminatory capacity.

STUDY DESIGN: Observational study of patients with scoliosis and matched controls. OBJECTIVES: To determine the validity and reliability of the modified Scoliosis Research Society Outcomes Instrument (SRS-22) for use in the assessment of deformity in adults. To demonstrate the discriminate validity of the SRS-22 in differentiating between affected and unaffected adults. SUMMARY OF BACKGROUND DATA: Spinal deformity has an important impact on the general health status of adults. The magnitude of this impact has been difficult to measure and reported variably in the literature. The development of disease-specific outcomes tools permits improved sensitivity and specificity in measuring the patient's self-assessment of health status. An instrument for measuring disease-specific health status in adults with scoliosis has not been validated. MATERIALS AND METHODS: Observational study comparing the health status of adults affected by scoliosis and unaffected controls, matched for age, gender, and socioeconomic status. Pearson correlation analysis was used to determine the relationship of each domain within the SRS-22 and SF-36 with radiographic parameters including sagittal balance, coronal balance, and major curve correction. Discriminate validity of the modified SRS instrument was determined by a comparison of means between affected and unaffected cohorts. The validation of the SRS-22 was determined by criterion validity, using correlation analysis with comparable domains of the SF-36. The reliability of the SRS-22 was demonstrated using test-retest parity and Cronbach's alpha test for internal consistency. RESULTS: One hundred eighty adults were included in the study, 146 with scoliosis and 34 without. Adults with scoliosis scored significantly lower than unaffected controls on every domain of the SRS-22 and the SF-36. The floor and ceiling effect of the SRS-22 were less than observed in the SF-36 instrument. Pearson correlation analysis demonstrated no significant correlation between any radiographic process measure and any specific domain within the SRS-22 or the SF-36 (r < 0.25). Comparison of similar domains in the SRS-22 and the SF-36 demonstrates high correlation between the instruments. Test-retest analysis similarly demonstrates a high degree of reproducibility in each domain (r = 0.83-0.94). Cronbach's alpha test of internal consistency within each domain demonstrates intercorrelation values greater than 0.75 within each domain of the SRS-22. CONCLUSIONS: Adult scoliosis has a significant and measurable impact on affected patients compared with controls. There is a poor correlation between radiographic parameters of outcome and patient self-assessment of health status. The SRS-22 is a reliable instrument in adults as demonstrated by a high degree of internal consistency and reproducibility. The SRS-22 is a valid instrument for use in adult deformity as demonstrated by the criterion validity assessment with the SF-36. The study supports the use of the SRS-22 in the adult spinal deformity population.

Adolescent↗
PubMed2003

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 degrees (range +40 to -47) before surgery, and increased to -42 degrees at follow-up (range -20 degrees to -60 degrees ), an increase of 19 degrees. 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.

Adult↗
PubMed2003

Treatment of thoracic pseudarthrosis in the adult: is combined surgery necessary?

In deformity surgery in adults, pseudarthrosis remains an important cause of progressive deformity and postoperative pain. Revision surgery for pseudarthrosis in the lumbar spine is a difficult challenge with failure rates of as much as 50% using posterior surgery alone. Treatment of pseudarthrosis of the thoracic spine has not been well-described. The purpose of the current study was to review the long-term clinical and radiographic results of posterior-only surgery for the treatment of pseudarthrosis in the thoracic spine. Using a posterior extension osteotomy through the identified pseudarthrosis with reinstrumentation and autogenous bone grafting, an improvement of regional sagittal balance was shown and reliable clinical outcomes were obtained. A single-stage posterior revision surgery with extension osteotomies through the regions of pseudarthrosis coupled with rigid internal fixation and autogenous bone grafting is an effective technique for treatment of pseudarthrosis of the thoracic spine. This technique improves regional sagittal deformity and leads to reliable arthrodesis. Combined anterior and posterior surgery was not necessary for effective treatment of thoracic pseudarthrosis in this series.

Adolescent↗
PubMed2003

Lumbar end plate osteotomy in adult patients with scoliosis.

The maintenance of mobile segments in the lumbar spine may prevent complications associated with long fusions to the sacrum and permit improved postoperative patient function and mobility. The purpose of the current study was to describe the technique of end plate osteotomy for surgical treatment of fractional curves in the lumbosacral region. This technique serves to allow the end lumbar vertebra to become horizontal, to reduce lumbosacral fractional curves, and to create a stable end vertebra above the pelvis. A review of long-term clinical and radiographic outcomes in patients treated with the technique have been satisfactory. The authors show that the techniques of end plate osteotomy with concave osteophyte excision is a clinically valuable technique for the treatment of adults with fixed lumbosacral fractional curves.

Adult↗
PubMed2002

Predictors of flexibility and pain patterns in thoracolumbar and lumbar idiopathic scoliosis.

STUDY DESIGN: A retrospective evaluation of radiographs in patients with idiopathic scoliosis was undertaken to assess predictors of flexibility. OBJECTIVE: To evaluate potential predictors of flexibility in patients with thoracolumbar and lumbar scoliosis. SUMMARY OF BACKGROUND DATA: Curve flexibility is an important consideration in the operative management of idiopathic scoliosis. Flexibility of the major curve is a useful predictor of expected surgical correction, and flexibility of compensatory curves determines whether they are structural or nonstructural. An accurate assessment of curve flexibility has important implications on surgical approaches and planning for deformity correction. The role of age and curve magnitude in predicting curve flexibility has not been well defined. A quantitative assessment of changes in curve flexibility with age and progression of deformity may yield important insight into the change in surgical management options over time. METHODS: A retrospective review of 75 patients with idiopathic thoracolumbar and lumbar scoliosis (age range 13-78 years) was undertaken. Preoperative standing and side-bending radiographs of thoracolumbar and lumbar curves were evaluated. Cobb angles of structural and fractional curves, curve flexibility, presence of lateral listhesis, and axial and radicular pain were documented. Predictors of structural and fractional curve flexibility were evaluated with correlation and regression analysis. Correlation analysis was used to demonstrate an association between radiographic findings and the clinical presentation. RESULTS: Seventy-five patients had an average major curve magnitude of 56 degrees (range 34-82 degrees ) with flexibility averaging 55% (range 20-93%). Structural curve flexibility was highly inversely correlated with both curve magnitude (r = -0.7; P< 0.001) and with age (r = -0.6; P< 0.001). Lumbar fractional curve (L4-S1) flexibility showed a high inverse correlation with age (r = -0.65; P< 0.001) but did not show correlation with Cobb angle. Thoracic compensatory curves showed a moderate correlation with Cobb angle (r = 0.53). Structural and fractional curve flexibility showed high correlation with each other (r = 0.5-0.66). Regression analysis yielded a formula to predict the flexibility of the structural curve (FSC): FSC = 130 - (Cobb + Age/2). Axial pain was correlated with age (r = 0.63); however, it was not correlated with curve magnitude. CONCLUSION: We have shown that curve magnitude and patient age are the main predictors of structural flexibility. Every 10 degrees increase in curve magnitude over 40 degrees results in a 10% decrease in flexibility; every 10-year increase in age decreases flexibility of the structural curve by 5% and the lumbosacral fractional curve by 10%. Curve magnitude and age of the patients are significant predictors of curve flexibility. The demonstration of this association offers useful information in estimating how surgical options for deformity correction may change over time.

Adolescent↗
PubMed2002

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.

Adult↗
PubMed2002

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 degrees, which improved to 16 degrees 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.

Adult↗
PubMedDate not supplied

Percutaneous plasma decompression alters cytokine expression in injured porcine intervertebral discs.

BACKGROUND CONTEXT: Discectomy is a surgical technique commonly used to treat bulging or herniated discs causing nerve root compression. Clinical data suggest discectomy may also help patients with contained discs and no clear neural compromise. However, the mechanisms of clinical efficacy are uncertain, and consequently bases for treatment optimization are limited. PURPOSE: To determine the effect of percutaneous plasma decompression on the histologic, morphologic, biochemical and biomechanical features of degenerating intervertebral discs. STUDY DESIGN: An adult porcine model of disc degeneration was used to establish a degenerative baseline against which to evaluate discectomy efficacy. OUTCOME MEASURES: Cytokines interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha were measured from tissue samples using enzyme-linked immunosorbent assay. Histology and morphology images were rated for degenerative findings (of cells and matrix) in both the nucleus and annulus. Proteoglycan content was determined, and intact specimen stiffness and flexibility were measured biomechanically. Magnetic resonance images were collected for biomechanical specimens. METHODS: Using a retroperitoneal surgical approach, stab incisions were made in four or five lumbar discs per spine in 12 minipigs. Animals were allocated into one of three groups: 6-week recovery, 12-week recovery and percutaneous plasma decompression using an electrosurgical device at 6 weeks with recovery for 6 additional weeks. Four additional animals served as controls. RESULTS: Discs treated with discectomy had a significant increase in IL-8 and a decrease in IL-1 as compared with the 12-week, nontreated discs. There were no significant differences in morphologic and biomechanical parameters or proteoglycan content between treated discs and time-matched, nontreated discs. CONCLUSIONS: Our results demonstrate that percutaneous plasma discectomy alters the expression of inflammatory cytokines in degenerated discs, leading to a decrease in IL-1 and an increase in IL-8. Whereas both IL-1 and IL-8 have hyperalgesic properties, IL-1 is likely to be a more important pathophysiologic factor in painful disc disorders than IL-8. Therefore, the alteration in cytokine expression that we observed is consistent with this effect as a mechanism of pain relief after discectomy. In addition, given that IL-1 is catabolic in injured tissue and IL-8 is anabolic, our results suggest that a percutaneous plasma discectomy may be capable of initiating a repair response in the disc.

Animals↗