Lumbar intervertebral disc disorder is a spinal condition that affects the normal function of the intervertebral discs mainly due to the natural aging process. This condition can manifest itself in pain and limited motion in the legs, amongst others. Posterolateral Fusion (PLF) and Posterior Lumbar Interbody Fusion (PLIF) are two of the most used surgical procedures for treating lumbar intervertebral disc disease. Although these procedures are commonly used and performed successfully the impact in terms of the stresses developed in the posterior implants employed and in the spinal components adjacent to the surgical site has not been exhaustively investigated. In addition, the consequences of the procedure on the reduction of the Range of Motion of the lumbar spine is not clearly understood. The objective of this research is to investigate the effect of one-level spinal fusion of lumbar segment L4-L5 on the stresses and the range of motion at the remaining, adjacent lumbar levels. Four 3 dimensional finite element models of a lumbosacral spine were created from Computer Tomography data (CT scan). The models were used to investigate four surgical scenarios, including the use of 0o and 4o interbody cages, in addition to the un-instrumented spine for flexion, extension, torsion and lateral bending motions. The predictions obtained from the models enabled the mechanical behaviour of the lumbar spine following fusion surgery using 0 o and 4o cages to be investigated and compared. In addition, a clinical study was performed to quantify the reduction in the range of motion for subjects who had undergone L4/5 posterior lumbar interbody fusion surgery. The clinical results were compared to those of subjects who had not undergone surgery and to the range of motion predictions from the computational model. The results from this research demonstrate that the insertion of posterior instrumentation does not have an impact on the spinal structures above the L3/4 intervertebral disc. However, the pedicle screws and the insertion of the interbody cages causes stress levels in the area adjacent to the surgical site to rise which could promote accelerated degeneration of the discs. Additionally, this study demonstrates how the pedicle screws are affected by the surgical spinal fusion techniques. Furthermore, the investigation demonstrates how posterior lumbar interbody fusion causes the range of motion of patients that had undergone this surgery to decrease. The results from the comparison of the behaviour of the use of 0º and 4º interbody cages in L4-5 posterolateral fusion demonstrates that the stress levels in the adjacent vertebrae, intervertebral discs and pedicle screw fixation system increase when 4º are used cages than when 0º cages were employed. The results from the in-vitro study show a decrease in the range of motion of the subjects who had undergone L4/5 posterior lumbar interbody fusion surgery when compared with the subjects with no low back pain history. This indicates that the PLIF surgery combined with the normal disc degeneration is subjected to higher stresses than the healthy spine.

M.Tech. / aim of this unblinded randomized control study was to compare Chiropractic Adjustive Therapy (CAT) to Interferential Current Therapy (IFC) as treatment for Painful Minor Intervertebral Dysfunction (PMID) in the lumbar spine. The effects of CAT and IFC on lumbar spine range of motion (ROM) and pain relief from PMID were also examined. The participants of the trials were treated at the Chiropractic Day Clinic at the University of Johannesburg. Thirty participants presenting with Low Back Pain (LBP) and PMID on segmental intervertebral examination were used for this study and divided into two groups of fifteen. Group A participants were treated with CAT applied to the painful intervertebral segment. Group B participants were treated with IFC over the painful intervertebral segment. The objective data for this research was recorded by the readings obtained from the application of transverse pressure by a Pressure Algometer to the lateral aspect of a painful spinous process. Further objective readings were taken using a Digital Inclinometer to measure the participants Range of Motion (ROM). Subjective data was obtained by an Oswestry Pain and Disability Index (ODI). The subjective and the objective data were both recorded at the first, fourth and seventh visit which took place over a three week period. The results of the study showed that Group A had a statistically significant decrease in Pressure Algometer Readings and ODI scores. Group A also showed a statistically significant improvement in ROM readings for Left Lateral Flexion, Left Rotation and Right Rotation. Group B did not show any statistical significance in either the subjective or objective data. Importantly, an Inter-group comparison for the Pressure Algometer Readings also revealed an increasing statistically significant difference between Group A and Group B from the first to the fourth and seventh visit. The pain elicited by transverse pressure to a spinous process is core to the diagnosis of PMID, which can result in many pain syndromes of vertebral origin (Maigne, 2006). This research provides evidence that CAT is more beneficial than IFC for the treatment of PMID in the lumbar spine over a short and longer period of time.