A Dissertation Submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the Degree of Master of Science January, 1990 / This is a study of the morphological and functional aspects of A. africanus thoracic and lumbar vertebrae in comparison with those of modern human and anthropoid ape vertebrae. The purpose is to determine if any derived features in the morphology of hominids, as distinct from primitive features shared with non-hominids, were present and if so to what stage of attainment of full erectness such features point. The major results of this study are as follows: (i) There is a difference in the configuration of the lumbar articular facets between pongids, on the one hand, and modern human and A. africanus, on the other hand. This difference suggests that similar stresses operate in these regions in the two hominid groups. (ii) Bony adaptation to a developed lumbar lordosis is present in A. africanus. (iii) Major agreement has been found in the relative dimensions of modern human and A. africanus lumbar vertebrae, in contrast to those of pongid vertebrae. This indicates probable correspondence in the pattern of weight transmission to the pelvis in modern humans and A. africanus. (iv) The decrease of inferior lumbar vertebral body area starts at higher levels in sts 14 (an A. africanus partial skeleton) than in modern man, suggesting a longer curved lower lumbar region in A. africanus. From these results it may be concluded that the trunk was probably carried in a fully erect posture in A. africanus. The bony adaptation thereto, however, may not have been fully developed as in modern man. It is proposed that, in Sts 14, the last two lumbar vertebrae were carried at an angle relative to each other and to the sacrum, in contrast to the abrupt change in direction between L5 and the sacrum in modern man.

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Lumbar fusion surgery is a commonly used procedure to treat severe spinal pathology and associated chronic disabling low back and leg pain. Despite the common incidence of spinal fusion surgery, few studies have examined patient outcomes or predictive correlates of this procedure. The objectives of this study were to characterize Utah workers who received lumbar fusion surgery in terms of relevant presurgical and outcome variables and to identify presurgical correlates of patient outcomes. An archival prospective research design was utilized consisting of a retrospective medical chart review and a postsurgical telephone outcome survey. Subjects were 203 workers' compensation patients from the state of Utah who have undergone spinal fusion surgery and who were at least 2 years postsurgery at time of follow-up. Outcomes were assessed for 144 of the 203 patients (71%). Presurgical measures _included demographic, work, compensation, disability, health, surgical, and physiological variables. Outcome measures included solid arthrosis, patient satisfaction, work disability status, functional disability due to back pain, and multidimensional health. Analysis of patient outcome data revealed that solid arthrosis was achieved in 71.9% of patients. Forty-six percent of subjects felt their back/leg pain problems were worse than what they had expected following the surgery, and 42 % felt that their quality of life had not changed or worsened as a result of lumbar fusion. Twenty-eight percent of fusion patients were work disabled at follow-up. Fusion patient mean outcome scores on multidimensional health measures reflected poorer health than comparative medical patient and nonpatient norms. The most consistent presurgical correlates across outcomes were lawyer involvement, number of prior low back operations, age at injury, and household income at time of injury. Results are compared to data from previous lumbar fusion research studies and reasons for varying findings are offered. Implications of the findings are discussed in terms of inadequate patient selection and insufficient assessment of patient outcomes in low back research studies. Limitations of the present research are discussed, including how placebo, natural history, and regression to the mean can lead to erroneous conclusions about the efficacy of lumber fusion surgery. Suggestions for improvements in low back surgery outcome research are offered.

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Background: In the clinical examination of patients with low back pain (LBP), musculoskeletal physiotherapists routinely assess lumbar spinal segmental motion by performing physical examination procedures such as observation of active range of motion and palpation of intervertebral motion. The validity of manual assessment of segmental motion, however, has not been adequately investigated. Methods: In this pragmatic, multi-centre, criterion-related validity study, 138 consecutive patients with LBP were recruited and examined by physiotherapists with postgraduate training in musculoskeletal manual therapy. Clinicians examined each patient�s spine for the presence of segmental motion abnormalities, described as lumbar segmental rigidity (LSR) and lumbar segmental instability (LSI), then referred the patients for flexion-extension (FE) radiographs. The physical examination procedures of interest were: 1) assessment of forward-bending (FB) active range of motion (AROM); 2) FB and backward-bending (BB) passive physiological intervertebral motion testing (PPIVMs) in the sagittal plane; and 3) central postero-anterior passive accessory intervertebral motion testing (PAIVMs). Sagittal displacement kinematics of the lumbar spinal segments were measured from the FE radiographs, and served as the criterion standard against which the clinical assessment results were compared. The kinematic parameters measured were sagittal rotation, sagittal translation, ratio of translation per degree of rotation (TRR), instantaneous axis of rotation (IAR), and centre of reaction (CR). Reference ranges for normal motion were calculated from the analysis of FE radiographs of 30 asymptomatic volunteers. The accuracy and validity of the clinical examination procedures were then calculated, and reported as sensitivity, specificity, and likelihood ratios for a positive test (LR+) and a negative test (LR-). Results: In patients with LBP, sagittal rotation LSR and sagittal translation LSR had a prevalence of approximately 5.7% (p <0.0005) in this cohort. Sagittal rotation LSI was not found in statistically significant numbers. Sagittal translation LSI was found at a prevalence of 3.6% (p <0.05). Abnormal TRR (23.3%), IAR (17.7%), and CR (16.5%) were more prevalent findings (all p <0.0005). Observation of the quantity of AROM, during FB, is not valid for the assessment of either total lumbar segmental sagittal rotation, or detection of individual segments with abnormal segmental motion. PPIVMs and PAIVMs are specific, but not sensitive, for the detection of rotation LSI and translation LSI. A positive test (grade 4 on a scale from 0 to 4) with BB PPIVMs may have some utility for the diagnosis of rotation LSI or translation LSI, with LR+ of 8.4 and 7.1 respectively (and 95% CIs from around 1.7 to 38). Likelihood ratio statistics for FB PPIVMs were not statistically significant. A positive test (grade 2 on a scale from 0 to 2) with PAIVMs may have some utility for the diagnosis of rotation LSI or translation LSI, with LR+ of 2.7 and 2.5 respectively (and 95% CIs from around 1.01 to 7.5). Neither PPIVMs nor PAIVMs were useful for the detection of LSR, or abnormal quality of motion as measured by TRR, CR, and IAR. Conclusions: Abnormal spinal segmental motion is associated with the symptom of LBP, in patients presenting to physiotherapists with a new episode of recurrent or chronic LBP, however prevalence is low due to highly variable lumbar segmental motion among asymptomatic individuals. Manual physical examination has moderate validity, but limited utility on its own, for the detection of translation LSI. Further research should investigate the utility of other clinical examination findings for the detection of lumbar segmental mobility disorders.

Qualitative studies investigating the sexual activity of people with low back pain found a substantial reduction in the frequency of coitus and have shown that pain during coitus due to mechanical factors (i.e., movements and postures) are the primary reason for this decreased frequency. However, a biomechanical analysis of coitus has never been done. The main objective of this study was to describe male and female lumbar spine and hip motion and muscle activation patterns during coitus and compare these motions and muscle activity across five common coital positions. Specifically, lumbar spine and hip motion in the sagittal plane and electromyography signal amplitudes of selected trunk, hip, and thigh muscles were described and compared. A secondary objective was to determine if simulated coitus could be used in place of real coitus for future coitus biomechanics research. Ten healthy males (29.3 ± 6.9 years, 176.5 ± 8.6 centimeters, 84.9 ± 14.5 kilograms) and ten healthy females (29.8 ± 8.0 years, 164.9 ± 3.0 centimeters, 64.2 ± 7.2 kilograms) were included for analysis in this study. These couples had approximately 4.7 ± 3.9 years of sexual experience with each other. This study was a repeated-measures design, where the independent variables, coital position and condition, were varied five (i.e., QUADRUPED1, QUADRUPED2, MISSIONARY1, MISSIONARY2, and SIDELYING) and two (i.e., real and simulated) times, respectively. Recruited participants engaged in coitus in five pre-selected positions (presented in random order) for 20 seconds per position first in a simulated condition, and again in a real condition. Three-dimensional (3D) lumbar spine and hip kinematic data were continuously collected for the duration of each trial by optoelectronic and electromagnetic motion capture systems. Electromyography (EMG) signals were also continuously collected for the duration of each trial. The kinematic data and EMG signals were collected simultaneously for both participants. Five sexual positions were chosen for this study based on the findings of previous literature and a biomechanical rationale. QUADRUPED – rear-entry, female quadruped, male kneeling behind – had two variations; in QUADRUPED1 the female was supporting her upper body with her elbows and in QUADRUPED2 the female was supporting her upper body with her hands. MISSIONARY – front-entry, female supine, male prone on top – also had two variations; in MISSIONARY1 the female was not flexing her hips or knees and the male was supporting his upper body with his hands, but in MISSIONARY2, the female was flexing her hips and knees and the male was supporting his upper body with his elbows. SIDELYING – rear-entry, female side-lying on her left side, male side-lying behind – did not have any variations. To determine if each coital position had distinct spine and hip kinematic and muscle activation profiles, separate univariate general linear models (GLM) (factor: coital position = five levels, α=0.05) followed by Tukey’s honestly significant difference (HSD) post hoc analysis were used. To determine if simulated coitus was representative of real coitus across all spine and hip kinematic and muscle activation outcome variables, paired-sample t-tests (α=0.05) were performed on all outcome variables for the real condition and their respective simulated values. In general, the coital positions studied showed that, for both males and females, coitus is mainly a flexion-extension movement of the lumbar spine and hips. Males used a greater range of their spine and hip motion in comparison to females. As expected, differences were found between coital positions for males and females and simulated coitus was not representative of real coitus, in particular the spine and hip kinematic profiles. The results found in this biomechanical analysis of common coital positions may be useful in a clinical context. It is recommended that during the acute stage of a low back injury resulting in flexion-, extension-, or motion-intolerance that coitus be avoided. If the LBP is a more chronic issue, particular common coital positions should be avoided. For the flexion-intolerant male patient, avoid SIDELYING and MISSIONARY2 as they were shown to require the most flexion. Both variations of QUADRUPED are the more spine-sparing of coital positions followed by, MISSIONARY1. Coaching the male patient on proper hip-hinging technique while thrusting – an easy technique to incorporate in both variations of QUADRUPED – will likely decrease spine movement and increase the spine-sparing quality of QUADRUPED. For the flexion-intolerant female patient, avoid both variations of MISSIONARY, especially with hip and knee flexion, as they were shown to elicit the most spine flexion. QUADRUPED2 and SIDELYING are the more spine-sparing coital positions, followed by QUADRUPED1. Subtle posture changes for a coital position should not be considered lightly; seemingly subtle differences in posture can change the spine kinematic profile significantly, resulting in a coital position that was considered spine-sparing becoming a position that should be avoided. Thus, spine-sparing coitus appears to be possible for the flexion-, extension-, and motion-intolerant patient. Health care practitioners may recommend appropriate coital positions and coach coital movement patterns, such as speed control and hip-hinging. With respect to future research in the area of sex biomechanics, using simulated coitus in replace of real coitus is not justifiable according to the data of this study. However, including a simulated condition did prove beneficial for increasing the comfort level of the couples and allowing time to practice the experimental protocol. Future directions may address female-centric positions (e.g., ‘reverse missionary’ with male supine and female seated on top), and back-pained patients with and without an intervention (e.g., movement pattern coaching or aides, such as a lumbar support).

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The need for the development of a rigorous analytical model of the lumbar spine to clarify the role of mechanical factors in low-back disorders has long been recognized. In response to this need, a general three dimensional nonlinear finite element program has been developed as part of this work and has been applied to the analysis of a lumbar L(,2-3) joint including the posterior elements. The analysis accounts for both the material and geometric nonlinearities and is based on a representation of the nucleus as an incompressible inviscid fluid and of the annulus as a composite of collagenous fibres embedded in a matrix of ground substance. The facet articulation has been accounted for by treating it as a general moving contact problem. The ligaments have been modelled as a collection of nonlinear axial elements. The geometry of the finite element model is based on in-vitro measurements. / The response of the joint under single compression, single flexion, single extension and also under flexion or extension combined with compression and sagittal shear has been analyzed for both the normal and degenerated states of the nucleus. Validity of the model has then been established by a comparison of those predictions which are also amenable to direct measurements. The states of strain and stress in different components of the lumbar joint have been thoroughly studied under all the foregoing loading conditions. / Those elements of the joint predicted to be vulnerable to mechanical failure or damage under the above types of loading have been identified. These results have been correlated with the lumbar joint injuries reported clinically. Furthermore, some joint injury mechanisms and degeneration processes have been proposed and the supporting clinical evidences have been presented.