Study purpose and background. Kinematic variables have been identified as potential biomarkers for low back pain patients; however, an in-depth comparison between chronic (n=22), acute (n=15), and healthy controls (n=136) has not been done. This retrospective data analysis compared intervertebral lumbar motion parameters, angular range of motion, translation, maximum disc height, motion share inequality (MSI) and variability (MSV), and laxity, between these groups. Methods and results. Kinematic parameters were determined using video tracking techniques utilising quantitative fluoroscopy (QF), during both weight-bearing and recumbent controlled sagittal bending tasks. Data was analysed for normality, and appropriate statistical tests were applied to determine differences between groups. There were no significant differences between the groups for age, height, weight and sex. Whilst few differences were found between acute and healthy groups, differences were shown between both chronic and healthy, and acute and chronic groups for all six parameters. Of particular note were examples of differences in the motion share parameters between the acute and chronic populations, with an increased MSI in the chronic group during recumbent flexion, and MSV during recumbent extension, and inversely an increase in MSV in the acute group during weight-bearing flexion. Conclusion. Analysis of intervertebral lumbar motion provides valuable insights into kinematic differences between chronic, acute, and healthy control populations. These findings suggest that there is variation between the groups which is knowledge that may benefit management strategies. Further exploration of the time varying data is warranted to explore how such differences may relate to the motion share inequalities and variability shown. Conflicts of Interest. No conflicts of interest. Sources of Funding. No funding obtained

Purpose & Background. Back and lower limb injuries are prevalent in athletes who perform novel weight-lifting techniques with inappropriate kinematics. Visual-auditory instructions and knowledge of performance (KP) verbal instructions are utilised to help novices execute novel skills. Effectiveness of these methods on executing appropriate front-squat lifting kinematics is limited. Aim: to investigate the effects of visual-auditory instructions compared to KP verbal instructions on front-squat kinematics at sticking point in novice lifters, with improvement determined by proximity to the kinematics of an expert lifter at sticking point when performing optimal front-squat lift. Methods. Twenty-four novices were randomised into two groups and performed front-squat lift. The novices in visual-auditory group (n = 12, age = 24.33 ± 2.93 years) received videoaudio instructions, verbal group (n = 12, Age= 22.66 ± 2.34 years) received KP verbal instructions. MATLAB software measured kinematic lumbar angles, Kinovea software measured hip, knee, ankle angles at sticking point of front-squat. Data were collected from video recordings of novices and an expert pre-and post-instructions in one session and expert data were used as reference values of proximity for both groups. Results. No significant differences were found between groups in lumbar, hip, knee, and ankle angles at sticking point of front-squat lift, where improvement was determined by proximity to expert lifter's angles. There was significant improvement with in lumbar angle of both groups and hip angle (verbal group). Conclusion. Visual-auditory instructions and verbal instructions have similar effects on the front-squat kinematics (lumbar spine, hip knee and ankle) of novice lifters. No Conflict of Interests. No funding was obtained

Background. Trunk muscle activity and thoraco-lumbar kinematics have been shown to discriminate non-specific chronic low back pain (NSCLBP) subgroups from healthy controls. Thoracic spine kinematics and muscle activity whilst intuitively associated with NSCLBP, has received less attention and the possibility of intra-regional interactions remains an area for exploration. Purpose. Determine relationships between muscle activation and kinematics in active extension pattern (AEP) and flexion pattern (FP) subgroups and no-low back pain controls during a sagittal bending task. Methods. Fifty NSCLBP subjects (27 FP, 23 AEP) and 28 healthy controls underwent 3D motion analysis (Vicon™) and surface electromyography whilst bending to retrieve a pen from the floor. Mean sagittal angle for the upper and lower thoracic and lumbar regions (UTx, LTx, ULx, LLx) were compared with normalised mean amplitude electromyography of 4 bilateral trunk muscles. Pearson correlations were computed to assess relationships. Results. Significant relationships between lumbar multifidus and ULx/LLx were identified in AEP during bending and return (p<0.01). FP exhibited multiple significant interactions including between longissimus thoracis and lumbar multifidus and LLx/LTx (p<0.035); and external oblique activity and UTx/LTx (p<0.05) during bending and return (and LLx during bending). Correlations were moderate to strong (r= −0.812 to 0.664). Conclusion. Kinematic and trunk muscle activity measurements differentiated between NSCLBP sub-groups and controls, especially between LLx kinematics and lumbar multifidus activity. Contrasting muscle activation patterns between LLx and LTx regions in FP highlights the importance of regional thoracic measurements, and suggests likely compensation strategies. Replication during other tasks should be evaluated in future studies. No conflicts of interest. Funding provided by Versus Arthritis (Formerly Arthritis Research UK)

Purpose and Background. Physical mechanisms underlying back pain impairment are poorly understood. Measuring movement features linked to back pain should help understand its causes and decide on best management. Previous kinematic studies have pointed to diverse features distinguishing back pain sufferers. However, the complexity of 3D kinematics means that it is difficult to choose, a priori, which variables or variable combinations are most important. This study set out to obtain a rich set of kinematic data from spinal regions and lower extremities during typical movement tasks, and analyse all of these variables simultaneously to obtain globally important distinguishing features. To this end, a novel distance metric between pairs of motion sequences was used to construct distance matrices. Analyses were carried out directly on these distance matrices. Methods and Results. 20 controls (age: 28 ± 7.6, 10 female) and 20 chronic LBP subjects (age: 41 ± 10.7, 4 female) were recruited. Kinematic data were obtained whilst subjects stood from sitting (‘STS’), picking up (‘Picking’) and lowering (‘Lowering’) a 5kg box, and walking (right (‘WalkRight’) and left sides (‘WalkLeft’)). For each task, permutation tests for group differences were carried out, based on the pseudo-F statistic calculated from the distance matrices. A similar approach was used to identify local differences at time points and joints. Group mean motion sequences were compared using a custom OpenSim model. Significant differences were obtained for STS (pseudo-F=2.8, p=0.017), WalkRight (pseudo-F=3.27, p=0.008) and WalkLeft (pseudo-F=3.39, p=0.005). Conclusion. Comparisons of movement tasks between groups revealed significant differences for STS and walking. Visualisation of group mean motion sequences, and local analyses assisted in the detailed understanding of these differences. This provides a visually intuitive means of studying complex motion differences between groups, without prior assumptions regarding which variables are important. No conflicts of interest. No funding. Original study funded by Arthritis Research UK MRC (Medical Research Council) Centre for Musculoskeletal Health and Work

Purpose and background. Recent research has identified possible functional biomarkers in chronic, nonspecific back pain (CNSLBP) based on intervertebral kinematics. Although excessive IV-RoM is no longer regarded as a clear motion abnormality, some studies have found subtle kinematic measures such as mid-range laxity and motion sharing inequality to be greater in CNSLBP patients. We studied a group of such patients who were investigated following failed interventions in terms of these subtle measures. Methods. Thirty-seven patients (mean age 47.5 years SD10.87, F14, M23) with CNSLBP that had recently failed to respond to a range of treatments and 37 healthy controls received passive recumbent lumbar intervertebral flexion assessments following a standardised quantitative fluoroscopy (QF) protocol. Groups were compared for motion sharing inequality (MSI) and variability (MSV) (L2-S1), for level by level laxity and translation, and with reference ranges of these from a separate group of healthy controls (n=54). Results. Patients had significantly higher MSI values than controls (p=0.01), but not MSV (p=0.79). Laxity and translation above normative reference limits were not more prevalent in patients. Eleven patients had had surgical or interventional procedures, 10 had spondylolisthesis or pars defects and 16 no disruptive elements. Those who had received invasive procedures (e.g. disc replacement, fusion) had significantly higher median MSI values than those with spondylolistheses/pars defects (p=0.02) or no disruption (p=0.001). Conclusion. Reduced individual level intervertebral restraint during passive recumbent motion was not associated with pain in treatment resistant patients, but uneven restraint between levels (MSI) appeared to be. Future work should investigate the reasons for this. No conflicts of interest. No funding obtained

Aims

Symptomatic spinal stenosis is a very common problem, and decompression surgery has been shown to be superior to nonoperative treatment in selected patient groups. However, performing an instrumented fusion in addition to decompression may avoid revision and improve outcomes. The aim of the SpInOuT feasibility study was to establish whether a definitive randomized controlled trial (RCT) that accounted for the spectrum of pathology contributing to spinal stenosis, including pelvic incidence-lumbar lordosis (PI-LL) mismatch and mobile spondylolisthesis, could be conducted.

Objectives. Many studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens. Methods. First, we validated the accuracy and repeatability of a custom-made mechanical loading equipment set-up. Eight lumbar specimens underwent CT scanning in flexion, neural, and extension positions by using the equipment set-up. The changes in the disc height and distance between adjacent two pedicle screw entry points (DASEP) of the posterior approach at different lumbar levels (L3/4, L4/5 and L5/S1) were examined on three-dimensional lumbar models, which were reconstructed from the CT images. Results. All the vertebral motion segments (L3/4, L4/5 and L5/S1) had greater changes in disc height and DASEP from neutral to flexion than from neutral to extension. The change in anterior disc height gradually increased from upper to lower levels, from neutral to flexion. The changes in anterior and posterior disc heights were similar at the L4/5 level from neutral to extension, but the changes in anterior disc height were significantly greater than those in posterior disc height at the L3/4 and L5/S1 levels, from neutral to extension. Conclusions. The lumbar motion segment showed level-specific changes in disc height and DASEP. The data may be helpful in understanding the physiologic dynamic characteristics of the lumbar spine and in optimising the parameters of lumbar surgical instruments. Cite this article: M. Fu, Q. Ye, C. Jiang, L. Qian, D. Xu, Y. Wang, P. Sun, J. Ouyang. The segment-dependent changes in lumbar intervertebral space height during flexion-extension motion. Bone Joint Res 2017;6:245–252. DOI: 10.1302/2046-3758.64.BJR-2016-0245.R1

Introduction. Low back pain (LBP) is the top leading global cause of years lived with disability. In order to examine LBP, researchers have typically viewed the spine in isolation. Clinically, it is imperative that the lower limbs are also considered. The aim of this study was to design a holistic and reliable multi-segmental kinematic model of the spine and lower limbs. Method. The spine was modelled according to easily identifiable anatomical landmarks, including upper thoracic (T1-T6), lower thoracic (T7-T12) and lumbar (L1-L5) segments. Pelvis, thigh, shank and foot segments were included. A 10-camera 3D motion capture system was used to track retro-reflective markers, which were used to define each segment of 10 healthy participants as they walked 3 times at a comfortable speed over a 6km walkway. The relative peak angles between each segment were calculated using the Joint Coordinate System convention and Intraclass Correlation Coefficients (ICCs) were used to determine intra-rater and inter-rater reliability (between an experienced clinician and biomechanical scientist). Results. Intra-rater and inter-rater ICCs were good to excellent (0.6–0.99). This implies that the system could be used reliably by one tester or by testers with limited anatomical expertise. Subjective participant reports implied that the system was acceptable and suitable for patient use (average application time of 10 minutes). Conclusion. The ‘Imperial Spinal Model’ is a holistic and reliable multi-segmental model. It is suitable for the kinematic assessment of the spine and could be used to enhance our understanding of a variety of spinal conditions. No conflicts of interest. Funding: Janet Deane is funded by an Allied Health Professional Doctoral Fellowship awarded by Arthritis Research U.K. (ARUK). Enrica Papi is funded by the National Centre of Excellence for Musculoskeletal Health and Work funded by ARUK and the Medical Research Council

Background. Previous work has identified differential kinematics and muscle activity between non-specific chronic low back pain (LBP) subgroups (flexion pattern (FP) and active extension pattern) and healthy controls. However, it is unclear if differences in muscle activity are maintained on resolution of pain and/or if they contribute to pain recurrence. Purpose. To investigate differences in trunk muscle activity between individuals with a history of flexion-related LBP (who are currently pain-free) and no-LBP controls during three functional activities. Methods. Fifteen individuals (10 male, 5 female) with a previous history of FP LBP (but who were currently pain-free) and 15 individuals with no history of low back pain (10 male, 5 female) were recruited. Surface electromyography of bilateral superficial lumbar multifidus, longissimus thoracis, transversus abdominus/internal oblique and external oblique muscle activity was recorded during three functional activities (sit-to-stand, step-up and bending to pick up a pen from the floor). Surface electromyography data was normalised (% maximum voluntary contraction) and compared between groups (Mann-Whitney U test). Results. No significant differences were observed for any muscle in any activity (p>0.05) except for significantly increased right superficial lumbar multifidus during the bending task (p=0.04) in the FP group compared to the control group (36.55 vs. 19.97 respectively). Conclusion. Individuals with resolved FP LBP have similar trunk muscle activation to those with no history of LBP. This suggests that muscle activity behaviours may ‘normalise’ in FP on resolution of pain. Further work should explore muscle activity during recurrent episodes to establish links with pain provocation. No conflicts of interest. No funding obtained

Purpose of the study. To incorporate magnetic resonance (MR) image data in a finite element (FE) model to estimate intervertebral disc stress as a function of posture. Background. Determining the stresses on the intervertebral discs is important for understanding disc degeneration and developing treatment strategies. The effect of different postures on disc stress has previously been investigated through disc pressure measurements and through computational modelling. Kinematic data derived from MR images and used in an FE model may provide a non-invasive way of assessing a wide range of subjects and postures. Methods. Two-dimensional FE models of the lumbar spine were created for four subjects. Vertebral bodies were modelled as rigid bodies, the disc was modelled with an isotropic elastic annulus (E = 2.5 MPa, ν=0.4) and nucleus (E = 1 MPa, ν=0.45). The geometry was defined from MR image data obtained in the supine posture; vertebral body translation and rotation were determined from images acquired in standing and sitting. Results. The principle stress distribution in standing and sitting differed between subjects. Stress peaks occurred in different discs (L4L5 v L5S1) and in different regions of the annulus (anterior v posterior). In three subjects the compressive stress at L4L5 was largest in sitting, for the fourth subject it was largest in standing; shear stress at L4L5 was highest in sitting for all four subjects. Conclusion. Kinematic data from MR images provides a way of assessing the effect of postural change on disc stress; inter-subject differences in L4L5 compressive stress are consistent with disc pressure measurements

Purpose and Background:. Despite the rise of back pain disability, objective mechanical assessment is generally lacking. Quantification of intervertebral kinematics using fluoroscopy provides objective measurement, but its use in clinical practice has not been assessed. This study reviewed cases referred to one UK site for lumbar spine quantitative fluoroscopic (QF) examinations and compared the reasons for referral with the findings reported. Methods and Results:. Fifty-seven consecutive referrals were reviewed. Patients underwent passive recumbent and/or weight-bearing active examinations in either the sagittal or both the sagittal and coronal planes. Data were extracted from anonymised QF reports and analysed for patient characteristics, reason for referral, working diagnosis at referral, level(s) of interest, previous surgical procedures and findings reported. Reports were also thematically analysed for key findings. Most patients had chronic back conditions of moderate or severe intensity. Most (38/57) were male, mean age 47 (SD 13.1) and mean complaint duration 5.4 years (0.3–32 years). They were referred mainly to investigate segmental instability (19/54) or spondylolisthesis (13/54) to inform either surgical referral or conservative management. Instability was reported in only 8/57 cases, but restricted and hypermobile levels in the same patient was also common (13/57). In 11 cases no mechanical abnormality was found. Conclusion:. QF studies were requested mainly to investigate instability and inform surgical referral, but segmental instability was more frequently suspected than found. Disproportionate motion sharing was not unusual. Longitudinal studies are needed to assess the effects of this investigation on care allocation, clinical decisions, patient outcomes and health care costs

Background and Purpose of Study:. Differences in regional lumbar angles in sitting have been observed between subgroups of NSCLBP patients exhibiting motor control impairments (MCI) (O'Sullivan, 2005; Dankaerts et al, 2006). However, differences in standing posture and other spinal regions are unknown. This study aimed to compare regional spinal angles in healthy and MCI subgroups in sitting and standing. Methods:. An observational, cross-sectional study investigated spinal kinematics of 28 Flexion Pattern (FP), 23 Active Extension Pattern (AEP) (O'Sullivan, 2005) and 28 healthy controls using 3D motion analysis (Vicon) during usual sitting and standing. Mean sagittal angle for Total Lumbar (TotLx), Total Thoracic (TotTx), Upper Thoracic (UTx), Lower Thoracic (LTx), Upper Lumbar (ULx) and Lower Lumbar (LLx) regions between groups were compared using one-way ANOVA. Results:. No differences in total thoracic and lumbar regions were observed, except TotLx in sitting between FP and AEP (Mean Difference (MD)=15.81°, p=0.003). Significant differences were observed in ULx and LTx for standing and sitting between FP and AEP (ULx Standing MD=9.89°, p=0.003; ULx Sitting MD=12.32°, p=0.000; LTx Standing MD=7.57°, p=0.05; LTx Sitting MD=11.72°, p=0.001) with AEP demonstrating greater extension in these regions. FP exhibited greater flexion compared to controls in ULx and LTx, except LTx in standing (ULx Standing MD=7.69°, p=0.018; ULx Sitting MD=6.96°, p=0.014; LTx Sitting MD=11.28°, p=0.001). No differences between AEP and controls were observed in sitting or standing. Conclusion:. Observing subdivided regional spinal angles is key to identifying MCI sub-group differences, with ULx and LTx able to discriminate between FP and AEP, and FP and healthy controls. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting. Conflicts of interest: No conflicts of interest. Sources of funding: Arthritis Research UK / Presidents Research Scholarship, Cardiff University

Statement of Purpose. It is well known that individuals with a history of low back pain (hLBP) exhibit altered movement patterns that are caused by changes in neuromuscular control. Postural disturbance provides an effective method for creating these differentiable movement patterns. This study has explored the response of the lower limb and spine to a translational perturbation similar to that experienced on public transport in healthy volunteers and those with hLBP. Methods. Healthy volunteers (n=16) and subjects with hLBP (n=10) were subjected to 31 identical postural disturbances at varying time intervals while standing atop a moving platform. Skeletal kinematics and muscle activation were recorded using a 10-camera Vicon system (Oxford, UK) and Myon electromyography (EMG) at the trunk (lumbar, lower thoracic, and upper thoracic segments), pelvis, thigh, calf, and foot. Joint angles were calculated using Body Builder (Vicon) and a unilateral seven-segment custom model. Results. Examination of the total range of joint motion (RoM) exhibited during the trial demonstrated similar RoM at the knee and hip (p=0.90 and 0.97 respectively), but less RoM for the hLBP group at the ankle and lumbar spine (p=0.21 and 0.38, respectively). EMG signals revealed higher muscle activation of the lower limbs from the hLBP cohort compared to healthy controls, yet greater activation at the gluteal and oblique muscles in the control group. Conclusions. In the presently small cohorts, trends demonstrate that differences in postural strategies exist between the healthy and hLBP cohorts, yet further testing of LBP patients will further clarify targets for rehabilitation

Background and purpose. Investigating inter-vertebral biomechanics in vivo using end-of-range imaging is difficult due to high intra subject variation, measurement errors and insufficient data. Quantitative fluoroscopy (QF) can reliably measure continuous motion but may suffer from contamination from uncontrolled loading and muscle contraction which compromises comparisons between studies and limits interpretation of results. This study presents the methods used to overcome these limitations. Methods and results. Forty chronic, non-specific low back pain (CNSLPB) patients and 40 matched controls underwent QF using a passive recumbent protocol which standardised the rate and range of trunk rotation, thus reducing intra-subject variation and excluding loading and muscle contraction factors. Left, right, flexion and extension were recorded from L2-5 and vertebral motion registered using image processing algorithms, Resultant continuous inter-vertebral rotation data were normalised to produce proportional contributions of each segment throughout the trunk bend. The expected continuous proportional contributions at each level and direction were determined by calculating reference intervals (mean +/− 2SD) from controls. Prevalence of patients exceeding these ranges was determined and the association with CNSLBP calculated using Chi-squared analysis. Additionally the variance of the normalised data throughout the continuous motion for each direction was determined and summed to produce an combined number. This was used to measure the difference between patients and controls and entered into ROC curve analysis to investigate discrimination between patients and controls. Conclusion. A methodology for assessment of the differences between the continuous in vivo spine kinematics of CNSLBP patients and healthy controls has been developed and will be presented

Objective. To compare the effectiveness of the Aspen, Aspen Vista, Philadelphia, Miami-J and Miami-J Advanced collars at restricting cervical spine movement in the sagittal, coronal and axial planes. Methods. Nineteen healthy volunteers (12 female, 7 male) were recruited to the study. Collars were fitted by an approved physiotherapist. Eight ProReflex (Qualisys, Sweden) infra-red cameras were used to track the movement of retro reflective marker clusters placed in predetermined positions on the head and trunk. 3D kinematic data was collected during forward flexion, extension, lateral bending and axial rotation from uncollared and collared subjects. The physiological range of motion in the three planes was analysed using the Qualisys Track Manager system. Results. The Aspen and Philadelphia collars were found to be significantly more effective at restricting movement in the sagittal plane compared to the Vista (p<0.001), Miami-J (p<0.001 and p<0.01) and Miami-J Advanced (p<0.01 and p<0.05) collars. The Aspen collar was significantly more effective at restricting axial rotation than the Vista (p<0.001) and the Miami-J (p<0.05) collars. The Aspen, Philadelphia, Miami-J and Miami-J Advanced collars were comparable at restricting lateral bending but the Vista was significantly less effective than all the collars at restricting movement in this plane. Conclusion. The Aspen collar was found to be superior to the other collars when measuring restriction of movement of the cervical spine in all planes, particularly the sagittal and transverse planes, while the Aspen Vista was the least effective collar

Statement of Purpose. The purpose of this experiment was to characterize the biomechanical properties of a minimally-invasive flexion-restricting stabilization system (FRSS) developed to address flexion instability. Background. Lumbar flexion instability is associated with degenerative pathology such as degenerative spondylolisthesis (DS) as well as resection of posterior structures during neural decompression. Flexion instability may be measured by increased total flexion/extension range of motion (ROM), as well as reduced stiffness within the high flexibility zone (HFZ, the range in which most activities occur). Flexion and segmental translation are known to be coupled; therefore increased flexion may exacerbate translational instability, particularly in DS. Method. Five cadaveric lumbar spines were tested intact; after L4-L5 destabilization including nucleotomy and midline decompression; and following restabilization with the FRSS secured to the spinous processes. Specimens were loaded in flexion (8Nm) and extension (6Nm) under 400N compressive follower preload. Flexion stiffness in the HFZ and segmental translation were also measured. Results. Destabilization increased L4-L5 flexion by 69%±31% (p<.01); decreased HFZ flexion stiffness 56%±12% (p=.01) and increased segmental translation 70%±49% from 1.5±0.4mm to 2.4±0.4mm (p<.01). With the FRSS segmental flexion was reduced by 45%±15% (p<.01); average HFZ flexion stiffness was increased by 232%±104% (p<.01); and segmental translation was reduced by 25%±9% to 1.8±0.2mm (p<.01). These values were not significantly different from the intact condition (p=.54, p=.21, p=.19). Discussion and Conclusion. The destabilization modeled here simulated degenerative and iatrogenic destabilizations often seen clinically. Implantation of the FRSS on the destabilized segments restored flexion, stiffness and translation to intact levels. The segmental coupling of translation and flexion seen in this experiment indicates that translation may be manipulated by altering flexion kinematics. The FRSS represents a novel system for treating flexion and translational instabilities

Aims

The aim of this study was to compare the peak pull-out force (PPF) of pedicle-lengthening screws (PLS) and traditional pedicle screws (TPS) using instant and cyclic fatigue testing.

Objectives

Loss of motion following spine segment fusion results in increased strain in the adjacent motion segments. However, to date, studies on the biomechanics of the cervical spine have not assessed the role of coupled motions in the lumbar spine. Accordingly, we investigated the biomechanics of the cervical spine following cervical fusion and lumbar fusion during simulated whiplash using a whole-human finite element (FE) model to simulate coupled motions of the spine.

Objectives

Pedicle-lengthening osteotomy is a novel surgery for lumbar spinal stenosis (LSS), which achieves substantial enlargement of the spinal canal by expansion of the bilateral pedicle osteotomy sites. Few studies have evaluated the impact of this new surgery on spinal canal volume (SCV) and neural foramen dimension (NFD) in three different types of LSS patients.

This prospective multicentre study was undertaken to determine segmental movement, disc height and sagittal alignment after total disc replacement (TDR) in the lumbosacral spine and to assess the correlation of biomechanical properties to clinical outcomes.

A total of 173 patients with degenerative disc disease and low back pain for more than one year were randomised to receive either TDR or multidisciplinary rehabilitation (MDR). Segmental movement in the sagittal plane and disc height were measured using distortion compensated roentgen analysis (DCRA) comparing radiographs in active flexion and extension. Correlation analysis between the range of movement or disc height and patient-reported outcomes was performed in both groups. After two years, no significant change in movement in the sagittal plane was found in segments with TDR or between the two treatment groups. It remained the same or increased slightly in untreated segments in the TDR group and in this group there was a significant increase in disc height in the operated segments. There was no correlation between segmental movement or disc height and patient-reported outcomes in either group.

In this study, insertion of an intervertebral disc prosthesis TDR did not increase movement in the sagittal plane and segmental movement did not correlate with patient-reported outcomes. This suggests that in the lumbar spine the movement preserving properties of TDR are not major determinants of clinical outcomes.

Cite this article: Bone Joint J 2013;95-B:81–9.