Biomedical subjects

Ashok Biyani

Publications and source records attributed to Ashok Biyani.

14 recordsLinked to original sources

PubMed2006

Biomechanical rationale for using polyetheretherketone (PEEK) spacers for lumbar interbody fusion-A finite element study.

STUDY DESIGN: To determine the effect of cage/spacer stiffness on the stresses in the bone graft and cage subsidence. OBJECTIVE: To investigate the effect of cage stiffness on the biomechanics of the fused segment in the lumbar region using finite element analysis. SUMMARY OF BACKGROUND DATA: There are a wide variety of cage/spacer designs available for lumbar interbody fusion surgery. These range from circular, tapered, rectangular with and without curvature, and were initially manufactured using titanium alloy. Recent advances in the medical implant industry have resulted in using medical grade polyetheretherketone (PEEK). The biomechanical advantages of using different cage material in terms of stability, subsidence, and stresses in bone graft are not fully understood. METHODS: A previously validated 3-dimensional, nonlinear finite element model of an intact L3-L5 segment was modified to simulate posterior interbody fusion spacers made of PEEK ("E" = 3.6 GPa) and titanium ("E" = 110 GPa) at the L4/5 disc with posterior instrumentation. Bone graft ("E" = 12 GPa) packed between the spacers in the intervertebral space was also simulated. The posterior lumbar interbody fusion spacer with instrumentation and graft represent a simulation of the condition present immediately after surgery. RESULTS: The peak centroidal Von Mises stresses in the graft bone increased by at least 9-fold with PEEK spacers as compared to titanium spacer. The peak centroidal Von Mises stresses in the endplates increased by at least 2.4-fold with titanium spacers over the PEEK spacers. These stresses were concentrated at places where the spacer interfaced with the endplate. The stiffness of the spacer did not affect the relative motion (stability) across the instrumented (L4/5) segment. CONCLUSIONS: Spacers less stiff than the graft will: (1) provide stability similar to titanium cages in the presence of posterior instrumentation, (2) reduce the stresses in endplates adjacent to the spacers, and (3) increase the load transfer through the graft, as evident from the increase in stresses in graft.

Benzophenones↗

PubMed2006

Biomechanics of two-level Charité artificial disc placement in comparison to fusion plus single-level disc placement combination.

BACKGROUND CONTEXT: Biomechanical studies of artificial discs that quantify parameters such as load sharing and stresses have been reported in literature for single-level disc placements. However, literature on the effects of using the Charité artificial disc (ChD) at two levels (2LChD) as compared with one-level fusion (using a cage [CG] and a pedicle screw system) plus one-level artificial disc combination (CGChD) is sparse. PURPOSE: To determine the effects of the 2LChD and CGChD across the implanted and adjacent segments. STUDY DESIGN: A finite element model of a L3-S1 segment was used to compare the biomechanical effects of the ChD placed at two lower levels (2LChD model) with L5-S1 fusion (using a CG and a pedicle screw system) plus L4-L5 level ChD placement combination (CGChD model). METHODS: We used our recently published and experimentally validated L3-S1 finite element model for the present study. The intact model was subjected to 400 N axial compression and 10.6 Nm of flexion/extension moments. The experimental constructs described above were then subjected to 400 N axial compression and a moment that produced overall motion equal to the intact model predictions (hybrid testing protocol). Resultant motion, loads across facets, and other parameters were analyzed at the experimental and adjacent levels. RESULTS: In flexion, the bending moments for the CGChD and 2LChD models were 15.4 Nm (fusion effect) and 7.3 Nm (increase in flexibility effect), respectively in comparison to 10.6 Nm for the intact model. The corresponding values in the extension mode were 11.2 Nm and 7.2 Nm. The predicted flexion rotations across the L5-S1 segment for the CGChD decreased by 76% (fusion effect), and increased at the L4-L5 and the L3-L4 levels by 68.5% and 28%, respectively. In the extension mode, motion across the L5-S1 segment decreased by 96.4% whereas it increased 74.6% and 18.2% across the L4-L5 and L3-L4 levels, respectively. For the 2LChD model, the flexion rotation across the L5-S1 segment increased by 28.2%. The motions across the L4-L5 and L3-L4 segments decreased by 12% and 24%, respectively. In extension, the corresponding changes were 10% increase, 10% increase, and 21% decrease at the L5-S1, L4-L5, and L3-L4 levels, respectively. The facet loads were in line with the changes in motion, except for the 2LChD case. CONCLUSIONS: The changes at L3-L4 level for both of the cases were of similar magnitude (approximately 25%), although in the CGChD model it increased and in the 2LChD model it decreased. The changes in motion at the L4-L5 level were large for the CGChD model as compared with the 2LChD model predictions (approximately 70% increase vs. 10% increase). It is difficult to speculate if an increase in motion across a segment, as compared with the intact case, is more harmful than a decrease in motion.

Biomechanical Phenomena↗

PubMed2006

Effect of lumbar interbody cage geometry on construct stability: a cadaveric study.

STUDY DESIGN: Biomechanical study to investigate three-dimensional motion behavior of cadaveric spines in various surgical simulations. OBJECTIVES: To determine the effect of cage geometry on the construct stability. SUMMARY OF BACKGROUND DATA: There is a wide variety of cage/spacer designs available for lumbar interbody fusion surgery. These range from circular, tapered, and rectangular with and without curvature. However, the effectiveness of cages with different designs and materials to stabilize a decompressed intervertebral space has not been fully studied. METHODS: Six fresh ligamentous lumbar spine specimens (L1-S2) were subjected to pure moments in the six loading directions. The resulting spatial orientations of the vertebrae were recorded using Optotrak Motion Measurement System. Measurements were made sequentially for intact, bilateral spacer placements across L4-L5 using a posterior approach, supplemented with pedicle screw-rod system fixation, and after the cyclic loading in flexion-extension mode. RESULTS: The stability tended to decrease after the bilateral cage placement as compared with the intact for all loading cases except flexion. In flexion, the angular displacement decreased to 80% of the intact. However, there was no significant statistical difference seen in stability between intact and after bilateral spacer placement. Following the addition of posterior fixation using pedicle screw-rod system, the stability significantly increased in all directions. Cyclic loading did not have any significant effect on the stability. CONCLUSIONS: Stand-alone cages restore motion to near-intact levels at best, and supplement instrumentation is essential for significantly increasing the stability of the decompressed segment. The effects of cage geometry and Young's modulus of the cage material do not seem to influence the stability, as compared with the other cagedesigns, especially after supplemental fixation with a posterior system.

Aged↗

PubMed2006

Three-dimensional finite element analysis of the pediatric lumbar spine. Part I: pathomechanism of apophyseal bony ring fracture.

The purpose of this study was to (1) develop a three-dimensional, nonlinear pediatric lumbar spine finite element model (FEM), and (2) identify the mechanical reasons for the posterior apophyseal bony ring fracture in the pediatric patients. The pediatric spine FE model was created from an experimentally validated three-dimensional adult lumbar spine FEM. The size of the FEM was reduced to 96% taking into account of the ratio of the sitting height of an average 14-years-old children to that of an adult. The pediatric spine was created with anatomically specific features like the growth plate and the apophyseal bony ring. For the stress analyses, a 10-N m moment was applied in all the six directions of motion for the lumbar spine. A preload of 351 N was applied which corresponds to the mean body weight of the 14-years-old group. The stresses at the apophyseal bony ring, growth plate and endplate were calculated. The results indicate that the structures surrounding the growth plate including apophyseal bony ring and osseous endplate were highly stressed, as compared to other structures. Furthermore, posterior structures in extension were in compression whereas in flexion they were in tension, with magnitude of stresses higher in extension than in flexion. Over time, the higher compression stresses along with tension stresses in flexion may contribute to the apophyseal ring fracture (fatigue phenomena).

Adult↗

PubMed2006

Three dimensional finite element analysis of the pediatric lumbar spine. Part II: biomechanical change as the initiating factor for pediatric isthmic spondylolisthesis at the growth plate.

A non-linear 3-dimensional finite element pediatric lumbar spine model with vertebral growth plate and apophyseal bony ring was developed. Lumbar spondylolysis was simulated in the model. The Von Mises stresses in the structures surrounding the vertebral growth plate, including apophyseal bony ring and osseous endplate were calculated in various loading modes. Instantaneous axis of rotation (IAR) path from flexion to extension was also analyzed. The results were compared with those of the intact model and the literature. The IAR path was at the posterior disc-endplate space of the lower vertebra in the intact spine, and moved cranially towards the upper-posterior disc space in the lytic spine. This was in agreement with in vivo radiological data by Sakamaki et al. [19]. During various loading modes, stresses in the spondylolytic pediatric model were higher than that of the intact model; ranging from 1.1 to 6.0 times, with the highest value in extension at the growth plate. In conclusion, FE models indicate that stress concentrations in the lytic model increase at the growth plate which may lead to physis stress fracture leading to spondylolisthesis.

Biomechanical Phenomena↗

PubMed2006

Effect of the increase in the height of lumbar disc space on facet joint articulation area in sagittal plane.

STUDY DESIGN: Computerized tomography (CT) of the lumbar spine cadaveric specimens was used to evaluate the effect of increasing the height of the disc space in the lumbar spine to the facet joint articulation in the sagittal plane. OBJECTIVE: To show how the facet joint articulation is affected by increasing the height of the disc space in the lumbar spine. SUMMARY OF BACKGROUND DATA: The Charité Artificial Disc (DePuy Spine, Inc., Raynham, MA) was successful in relieving low back pain in the majority of patients, yet there was still a significant number of patients who did not obtain pain relief, or their pain even worsened. The etiology of their pain is still not known. To our knowledge, no study has addressed the effect on the facet joints when the disc height is increased. METHODS: CT images passing through the center of the L3-S1 facet joints (sagittal plane) were obtained from 15 cadaveric lumbar spine specimens. The articulation overlap of facet joints in sagittal plane from the L3 to S1 was measured. A 1-mm incremental increase to a total 5 mm in disc space height was performed to simulate the changes seen in disc replacement. The change in the facet joint articulation overlap in sagittal plane at normal and each displacement was then measured. There were 5 lumbar spine specimens dissected to validate the technique and standardize the measurements. Mean, percentages, and standard deviation values were calculated for all measured dimensions. RESULTS: No significant difference was found between the measurements on CT and gross specimens (P > 0.05). In 15 specimens, the mean facet joint articulation overlap on the sagittal plane was: 16.29 +/- 1.20 mm (left) and 16.22 +/- 1.16 (right) at the L3-L4 level; 17.81 +/- 1.18 mm (left) and 17.74 +/- 1.18 mm (right) at the L4-L5 level; and 18.18 +/- 1.18 mm (left) and 18.23 +/- 1.15 mm (right) at the L5-S1 level. There is no significant difference between the measured values on left and right sides (P > 0.05). Each 1-mm incremental increase in disc space at the L3-L4 level translated to a decrease in the facet joint articulation overlap in the sagittal plane by 6%, and the mean facet joint space increased 0.4 mm. At the L4-L5 level, the articulation overlap decreased by 6%, and the facet joint space increased 0.5 mm. At the L5-S1 level, the articulation overlap decreased by 4%, and the facet joint space increased 0.7 mm. CONCLUSIONS: There is a significant decrease of the facet joint articulation overlap in sagittal plane and an increase in the facet joint space following an increase in the lumbar disc space. The inappropriate increase of the height of disc space will result in facet joint subluxation.

Humans↗

PubMed2006

MRI signal changes of the pedicle as an indicator for early diagnosis of spondylolysis in children and adolescents: a clinical and biomechanical study.

STUDY DESIGN: Clinical review of pediatric patients with lumbar spondylolysis and biomechanical analysis using finite-element lumbar spine model. OBJECTIVES: To evaluate the usefulness of the signal changes observed on MR images of the pedicle for the early diagnosis of spondylolysis, and to investigate the pathomechanism of the signal changes based on the stresses in pedicles, as predicted using finite-element analyses. Furthermore, to evaluate the usefulness of the signal change to predict the bony healing following conservative treatment. SUMMARY OF BACKGROUND DATA: Since early-stage spondylolysis can achieve osseous healing conservatively, it is important to diagnose this disorder as early as possible. Presently, there is no well-established, noninvasive, and reliable diagnostic tool for the early diagnosis. METHODS: Thirty-seven pediatric patients with spondylolysis were included. Sixty-eight defects were examined and their stages as revealed on CT scans were recorded. High signal changes (HSC) of the pedicles on axial T2-weighted MRI were compared with the CT-based stages of the defect. Among them, 16 patients, including 15 boys and 1 girl, were treated conservatively for at least a 3-month period. Bony healing of the fracture site was evaluated on CT, and the results were compared between two groups with or without HSC at the initial consultation. Using a three-dimensional nonlinear finite-element model of the L3-L5 segment, stress distributions in the pars and pedicle regions were analyzed in response to 400 N compression and 10.6 Nm moment. RESULTS: Based on CTs, 68 pars defects were classified as follows: 8 very early, 24 late-early, 16 progressive, and 20 terminal stages. All defects in very early and late-early stages (100%) showed HSC on T2-weighted MRI at the ipsilateral pedicle. Among 16 progressive stages, eight (50%) showed HSC, while no defects of the terminal stage (0%) were found to have HSC. In total, 29 pars defects were treated conservatively out of 16 patients. In 19 of the HSC positive defects, 15 (79%) showed bony healing after the conservative treatment, whereas none of the 10 HSC negative defects (0%) showed any healing. The results were statistically significant at P < 0.05 (chi). Stress results from the finite-element model indicated that pars interarticularis showed the highest value in all loading modes, and the pedicle showed the second highest. CONCLUSIONS: The correlation between the high stresses in the pedicle and the corresponding HSC suggest that signal changes in MRI could be used as an indicator for early diagnosis of spondylolysis. The HSC of the pedicle provided useful information to diagnose early stage spondylolysis. Furthermore, the HSC may be a good indicator as to whether a bony union will result from conservative treatment.

Adolescent↗

PubMed2005

Effects of charité artificial disc on the implanted and adjacent spinal segments mechanics using a hybrid testing protocol.

STUDY DESIGN: Finite element model of L3-S1 segment and confirmatory cadaveric testing were used to investigate the biomechanical effects of a mobile core type artificial disc (Charité artificial disc; DePuy Spine, Raynham, MA) on the lumbar spine. OBJECTIVE: To determine the effects of the Charité artificial disc across the implanted and adjacent segments. SUMMARY OF BACKGROUND DATA: Biomechanical studies of artificial discs that quantify parameters, like the load sharing and stresses, are sparse in the literature, especially for mobile-type core artificial disc designs. In addition, there is no standard protocol for studying the adjacent segmental effects of such implants. METHODS: Human osteo-ligamentous spines (L1-S1) were tested before and after L5-S1 Charité artificial disc placement. The data were used to validate further an intact 3-dimensional (3-D) nonlinear L3-S1 finite element model. The model was subjected to 400-N axial compression and 10.6 Nm of flexion/extension pure moments (load control) or pure moments that produced the overall rotation of the L3-S1 Charité model equal to the intact case (hybrid approach). Resultant motion, load, and stress parameters were analyzed at the experimental and adjacent levels. RESULTS: Finite element model validation was achieved only with the load-controlled experiments. The hybrid approach, believed to be more clinically relevant, revealed that Charité artificial disc leads to motion increases in flexion (19%) and extension (44%) at the L5-S1 level. At the instrumented level, the decrease in the facet loads was less than at the adjacent levels; the corresponding decrease being 26% at L3-L4, 25% at L4-L5, and 13.4% at L5-S1 when compared to the intact. Intradiscal pressure changes in the L4-L5 and L3-L4 segments were minimal. Shear stresses at the Charité artificial disc-L5 endplate interface were higher than those at S1 interface. However, in the load control mode, the increase in facet loads in extension was approximately 14%, as compared to the intact case. CONCLUSIONS: The hybrid testing protocol is advocated because it better reproduces clinical observations in terms of motion following surgery, using pure moments. Using this approach, we found that the Charité artificial disc placement slightly increases motion at the implanted level, with a resultant increase in facet loading when compared to the adjacent segments, while the motions and loads decrease at the adjacent levels. However, in the load control mode that we believe is not that clinically relevant, there was a large increase in motion and a corresponding increase in facet loads, as compared to the intact.

Biomechanical Phenomena↗

PubMed2005

Pathomechanism of ligamentum flavum hypertrophy: a multidisciplinary investigation based on clinical, biomechanical, histologic, and biologic assessments.

STUDY DESIGN: A multidisciplinary study involving clinical, histologic, biomechanical, biologic, and immunohistologic approaches. OBJECTIVE.: To clarify the pathomechanism of hypertrophy of the ligamentum flavum. SUMMARY OF BACKGROUND DATA: The most common spinal disorder in elderly patients is lumbar spinal canal stenosis, causing low back and leg pain, and paresis. Canal narrowing, in part, results from hypertrophy of the ligamentum flavum. Although histologic and biologic literature on this topic is available, the pathomechanism of ligamentum flavum hypertrophy is still unknown. METHODS: The thickness of 308 ligamenta flava at L2/3, L3/4, L4/5, and L5/S1 levels of 77 patients was measured using magnetic resonance imaging. The relationships between thickness, age, and level were evaluated. Histologic evaluation was performed on 20 ligamentum flavum samples, which were collected during surgery. Trichrome and Verhoeff-van Gieson elastic stains were performed for each ligamentum flavum to understand the degree of fibrosis and elastic fiber status, respectively. To understand the mechanical stresses in various layers of ligamentum flavum, a 3-dimensional finite element model was used. Von Mises stresses were computed, and values between dural and dorsal layers were compared. There were 10 ligamenta flava collected for biologic assessment. Using real-time reverse transcriptase polymerase chain reaction, transforming growth factor (TGF)-beta messenger ribonucleic acid expression was quantitatively measured. The cellular location of TGF-beta was also confirmed from 18 ligamenta flava using immunohistologic techniques. RESULTS: The ligamentum flavum thickness increased with age, however, the increment at L4/5 and L3/4 levels was larger than at L2/3 and L5/S1 levels. Histology showed that as the ligamentum flavum thickness increased, fibrosis increased and elastic fibers decreased. This tendency was more predominant along the dorsal side. Von Misses stresses revealed that the dorsal fibers of ligamentum flavum were subjected to higher stress than the dural fibers. This was most remarkably observed at L4/5. The largest increase in ratio observed between the dorsal and dural layer was approximately 5-fold in flexion at L4/5 in flexion. Expression of TGF-beta was observed in all ligamenta flava, however, the expression decreased as the ligamentum flavum thickness increased. Immunohistochemistry showed that TGF-beta was released by the endothelial cells, not by fibroblasts. CONCLUSIONS: Fibrosis is the main cause of ligamentum flavum hypertrophy, and fibrosis is caused by the accumulation of mechanical stress with the aging process, especially along the dorsal aspect of the ligamentum flavum. TGF-beta released by the endothelial cells may stimulate fibrosis, especially during the early phase of hypertrophy.

Adolescent↗

PubMed2005

Athletes with unilateral spondylolysis are at risk of stress fracture at the contralateral pedicle and pars interarticularis: a clinical and biomechanical study.

BACKGROUND: Unilateral spondylolysis is common in youths; its clinical and biomechanical features, especially effects on the contralateral side, are not fully understood. HYPOTHESIS: Unilateral spondylolysis predisposes the contralateral side to stress fracture, especially in athletes actively engaged in sporting activities involving torsion of the trunk. STUDY DESIGN: Case series and descriptive laboratory study. METHODS: Thirteen athletes younger than age 20 with unilateral spondylolysis were included. The contralateral pedicle and pars of spondylolytic vertebrae were examined using computed tomography and magnetic resonance imaging. Using a finite element model of the intact ligamentous L3-S1 segment, stress distributions were analyzed in response to 400-N axial compression and 10.6-N.m moment in flexion, extension, lateral bending, and axial rotation. Unilateral spondylolysis was created in the model at L5. The stress results from the unilateral defect model were compared to the intact model predictions and correlated to the contralateral defects seen in patients. RESULTS: Among 13 patients, there were 6 early-, 2 progressive-, and 5 terminal-stage defects. Three (23.1%) showed contralateral stress fracture. Among them, 2 belonged to the progressive-stage and 1 to the terminal-stage spondylolysis group. The remaining 4 patients in the terminal defect group showed stress reactions, such as sclerosis at the contralateral pedicle. In the finite element analysis model with an L5 left spondylolysis, the stresses at the contralateral and pars interarticularis were found to increase in all loading modes, with increases as high as 12.6-fold compared to the intact spine. CONCLUSIONS: Unilateral spondylolysis could lead to stress fracture or sclerosis at the contralateral side due to an increase in stresses in the region. CLINICAL RELEVANCE: Surgeons should be aware of possibility of contralateral stress fractures in cases in which patients, especially athletes engaged in active sports, show unilateral spondylolysis and persistent low back pain complaints.

Adolescent↗

PubMed2003

Intradiscal electrothermal therapy: a treatment option in patients with internal disc disruption.

STUDY DESIGN: A literature review was conducted. OBJECTIVES: To review the anatomy, pathophysiology, diagnosis, procedure, and clinical results of intradiscal electrothermal therapy (IDET). SUMMARY OF BACKGROUND DATA: Low back pain is a major physical and socioeconomic entity. A significant percentage of low back pain is attributable to internal disc disruption. The management of internal disc disruption has traditionally been limited to either conservative treatment or spinal fusion. IDET has been performed as an alternative to these therapies. METHODS: The available literature was reviewed. RESULTS: Scientific data regarding the pathophysiology, biologic effects, and clinical results are relatively scarce. Early biomechanical and histologic investigations into the effects of IDET are conflicting. However, in early prospective human trials, IDET seems to provide some benefit with little risk. CONCLUSIONS: IDET is potentially beneficial treatment for internal disc disruption in carefully selected patients as an alternative to spinal fusion. More basic science and clinical research with long-term follow-up evaluation is necessary.

Clinical Trials as Topic↗

PubMed2003

Effects of slip severity and loading directions on the stability of isthmic spondylolisthesis: a finite element model study.

STUDY DESIGN: Using a validated finite element model, the biomechanical effects of pars defect in a lumbar segment with and without different degrees of slip (up to 50% slip) were studied. OBJECTIVES: To study the effects of slip severity and loading parameters on the stability of the lytic and adjacent motion segments. Better knowledge of the biomechanics of spondylolisthesis may help formulate treatment strategies such as bracing or spinal implants. SUMMARY OF THE BACKGROUND DATA: Clinically, spondylolisthesis exists in varying grades of anterior slip, and the biomechanical stability of the motion segments at the lytic defect and adjacent level probably varies as well. In vitro studies of L4-L5 and L5-S1 isthmic spondylolisthesis slips have concluded that an L4-L5 pars defect is more unstable than an L5-S1 pars defect. Comparing the stability of lytic motion segments with different grades of spondylolisthesis is difficult to do experimentally and therefore has not been done. Further assessing the stresses in the bone and intervertebral discs at or adjacent to a lytic defect is also difficult to study experimentally, so no data are available. METHODS: A finite element model of L4-S1 was validated with and without a pars defect at L5. The model was then revised to represent different degrees of slip at L5, and six different moment loadings were applied. RESULTS: The current study showed larger decrease in stiffness with increasing percent slip. The decrease in disc stiffness and increase in disc stresses with increasing percent slip were larger at the level of spondylolisthesis as compared to the changes in the adjacent segment. Lateral bending moment and torsion load showed the largest decrease in stiffness due to slip. At 50% slip, the maximum increase in motion (as compared to motion in an intact segment) was seen under lateral bending moment load (about 55% at L4/L5 and 250% at L5/S1). Lateral bending also produced the largest increase in stresses due to 50% slip in the anulus and endplates (300% increase in anular stress and 190% increase in endplate stress) at L5/S1. CONCLUSIONS: The stiffness of a spondylolisthetic motion segment decreases as the slip increases. Lateral bending and torsion are moment directions causing the greatest resulting motions.

Biomechanical Phenomena↗

PubMed2003

Percutaneous computed tomographic stabilization of the pathologic sacroiliac joint.

Metastases to the sacroiliac joint region can be a source of significant pain in many patients who are terminally ill. Six patients with metastatic lesions in the sacroiliac region who presented with significant posterior pelvic pain were treated with computed tomography-guided insertion of iliosacral screws. All patients reported excellent pain control in the early postoperative period. Computed tomography-guided insertion of iliosacral screws in an area of relatively preserved bone stock provides good purchase of the screws. It is a safe percutaneous procedure and it helps alleviate pain in patients with sacroiliac metastases.

Aged↗

PubMedDate not supplied

Low back pain: pathophysiology and management.

Basic research is advancing the understanding of the pathogenesis and management of low back pain at the molecular and genetic levels. Frequently, low back pain is caused by disorders of the intervertebral disk. Cytokines such as matrix metalloproteinases, phospholipase A2, nitric oxide, and tumor necrosis factor-alpha are thought to contribute to the development of low back pain. Drugs are being developed to modulate these chemical mediators. Recent research using growth factors to promote chondrocyte regeneration appears to be promising. Advances in gene therapy to both prevent disk degeneration and regenerate the disk eventually may have clinical application.

Analgesics↗