Klas Halldin

Three-dimensional radiological classification of lumbar disc herniation in relation to surgical outcome

Centrally located lumbar disc herniations have been reported to be of predictive value for poor post-operative clinical outcome. One hundred and fifty patients undergoing lumbar disc herniation surgery were prospectively included. Herniation-related parameters, including the grading of contours, were assessed from pre-operative computed tomography (CT) and magnetic resonance imaging (MRI) images using a new three-dimensional grading system. The radiological findings were compared with outcome parameters two years post-operatively (patient-assessed pain, function/health scores and evaluation by an independent observer). An intra- and inter-observer validation of the classification was performed in a subgroup of patients. High intra-observer and good inter-observer reliability for both CT and MRI was seen. In the study population, no relation between the distribution or size of the herniations and outcome at 2-year follow-up were found. The distribution and size of the lumbar disc herniations with the three-dimensional classification were not found to be of importance for the clinical outcome.RésuméLes hernies discales lombaires sur la partie centrale du disque ont été accusées d’entraîner une évolution clinique peu satisfaisante. Matériel et méthode : 150 patients ayant présenté une hernie discale lombaire opérée ont été inclus de façon prospective. Les paramètres relatifs à la hernie ont été classés à l’aide du scanner et de l’IRM en utilisant un système de classement tridimensionnel. Les paramètres radiologiques ont été comparés aux paramètres d’évolution clinique en post-opératoire (douleur-fonction) et évalués par un observateur indépendant en utilisant le score de Macnab avec une étude intra et inter observateurs pour chaque sous-groupe de patients. Résultats, il n’a été trouvé aucune relation significative entre l’évolution et la localisation de la hernie à deux ans de suivi post-opératoire. En conclusion : la localisation et l’aspect de la hernie n’ont pas d’influence sur le devenir clinique des patients.

Health-related quality of life in patients with surgically treated lumbar disc herniation: 2- and 7-year follow-up of 117 patients

Background and purpose Health-related quality of life (HRQoL) instruments have been of increasing interest for evaluation of medical treatments over the past 10–15 years. In this prospective, long-term follow-up study we investigated the influence of preoperative factors and the change in HRQoL over time after lumbar disc herniation surgery. Methods 117 patients surgically treated for lumbar disc herniation (L4-L5 or L5-S1) were evaluated with a self-completion HRQoL instrument (EQ-5D) preoperatively, after 2 years (96 patients) and after 7 years (89 patients). Baseline data (age, sex, duration of leg pain, surgical level) and degree of leg and back pain (VAS) were obtained preoperatively. The mean age was 39 (18–66) years, 54% were men, and the surgical level was L5-S1 in 58% of the patients. The change in EQ-5D score at the 2-year follow-up was analyzed by testing for correlation and by using a multiple regression model including all baseline factors (age, sex, duration of pain, degree of leg and back pain, and baseline EQ-5D score) as potential predictors. Results 85% of the patients reported improvement in EQ-5D two years after surgery and this result remained at the long-term follow-up. The mean difference (change) between the preoperative EQ-5D score and the 2-year and 7-year scores was 0.59 (p < 0.001) and 0.62 (p < 0.001), respectively. However, the HRQoL for this patient group did not reach the mean level of previously reported values for a normal population of the same age range at any of the follow-ups. The changes in EQ-5D score between the 2- and 7-year follow-ups were not statistically significant (mean change 0.03, p = 0.2). There was a correlation between baseline leg pain and the change in EQ-5D at the 2-year (r = 0.33, p = 0.002) and 7-year follow-up (r = 0.23, p = 0.04). However, when using regression analysis the only statistically significant predictor for change in EQ-5D was baseline EQ-5D score. Interpretation Our findings suggest that HRQoL (as measured by EQ-5D) improved 2 years after lumbar disc herniation surgery, but there was no further improvement after 5 more years. Low quality of life and severe leg pain at baseline are important predictors of improvement in quality of life after lumbar disc herniation surgery.

The effect of standard lumbar discectomy on segmental motion: 5-year follow-up using radiostereometry

We measured the effects of lumbar discectomy on segmental motion over a period of 5 years. Twenty-four patients with lumbar disc herniation were treated by standard lumbar discectomy at the L4–L5 or L5–S1 level. Peroperatively, tantalum markers were inserted into L4, L5, and the sacrum. Radiostereometric analysis was performed at discharge from hospital and 5 years postoperatively. The treated level was compared with the corresponding untreated level. Thus, patients who had discectomy at the L4–L5 level served as controls for patients with L5–S1 lesions and vice versa. The relative rotation and translation in relation to the three cardinal axes were calculated. Inducible displacements over the two discs were calculated between the supine and standing positions. At the L4–L5 level, there were no differences in inducible displacements between the operated and control levels at discharge or 5 years postoperatively. At the L5–S1 level we found decreasing inducible movement in the sagittal plane over time for discectomy patients. The reason for decreasing mobility over time after discectomy at the L5–S1 but not at the L4–L5 level is unknown. Mechanical factors caused by the more vertical orientation of the L5–S1 disc in combination with degenerative changes could be one explanation.RésuméNous avons mesuré les effets de la discectomie lombaire sur la mobilité segmentaire sur une période de 5 années. Vingt-quatre malades avec une hernie discale lombaire ont été opérés par discectomie standard au niveau L4–L5 ou L5–S1. Des marqueurs en tantale ont été insérés en peropératoire dans L4, L5 et le sacrum. L’analyse radiostéréométrique a été exécutée à la sortie de l’hopital et 5 ans après l’intervention. Le niveau opéré a été comparé avec le niveau non-opéré correspondant. Donc, les malades opérés sur L4–L5 ont servi comme contrôles pour malades opérés sur L5–S1 et vice versa. La rotation et la translation relatives selon les trois axes cardinaux ont été calculées. Les déplacements induits sur les deux disques ont été calculés entre les positions debout et couché sur le dos. Sur L4/L5 il n’y avait pas de différences dans les déplacements induits entre les opérés et le contrôle initial ou 5 ans aprés. Sur L5/S1 nous avons trouvé avec le temps des mouvements induits décroissants dans le plan sagittal pour les malades opérés. La raison de la mobilité décroissante avec le temps après discectomie L5–S1 mais pas au niveau L4–L5 est inconnue. Les facteurs mécaniques en relation avec l’orientation plus verticale du disque L5–S1, en association avec l’évolution dégénérative pourraient être une explication.

A Comparison of Radiostereometric Analysis and Computed Tomography for the Assessment of Lumbar Spinal Fusion in a Sheep Model

Study Design Prospective animal study. Objective The aim of this animal study is to evaluate the accuracy of radiostereometric analysis (RSA) compared with computed tomographic (CT) scan in the assessment of spinal fusion after anterior lumbar interbody fusion (ALIF) using histology as a gold standard. Methods Three non-adjacent ALIFs (L1–L2, L3–L4, and L5–L6) were performed in nine sheep. The sheep were divided into three groups of three sheep. All the animals were humanely killed immediately after having the last scheduled RSA. The lumbar spine was removed and in vitro fine cut CT and histopathology were performed. Results Using histological assessment as the gold standard for assessing fusion, RSA demonstrated better results (100% sensitivity and 66.7% specificity; positive predictive value [PPV] = 27.3%, negative predictive value [NPV] =100.0%) compared with CT (66.7% sensitivity and 60.0% specificity [PPV = 16.7%, NPV = 93.8%]). Conclusions RSA demonstrated higher sensitivity and specificity when compared with CT. Furthermore, RSA has the advantage of much lower radiation exposure compared with fine cut CT. Further studies are required to see if RSA remains superior to CT scan for the assessment spinal fusion in the clinical setting. Assessment of Class of Evidence (CoE) for individual studies of diagnostic test evaluation Methodological principle Study design Prospective cohort design X Retrospective cohort design Case–control design Broad spectrum of patients with expected condition a Appropriate reference standard used X Adequate description of test and reference for replication X Blinded comparison with appropriate reference X Reference standard performed independently of test X Evidence level II Note: Blank box indicates criterion not met, could not be determined, or information not reported by author or was not reported. aThis study contained nine animal subjects.

RSA in Spine: A Review

Study Design: Systematic review of literature. Objectives: This systematic review was conducted to investigate the accuracy of radiostereometric analysis (RSA), its assessment of spinal motion and disorders, and to investigate the limitations of this technique in spine assessment. Methods: Systematic review in all current literature to invesigate the role of RSA in spine. Results: The results of this review concluded that RSA is a very powerful tool to detect small changes between 2 rigid bodies such as a vertebral segment. The technique is described for animal and human studies for cervical and lumbar spine and can be used to analyze range of motion, inducible displacement, and fusion of segments. However, there are a few disadvantages with the technique; RSA percutaneous procedure needs to be performed to implant the markers (and cannot be used preoperatively), one needs a specific knowledge to handle data and interpret the results, and is relatively time consuming and expensive. Conclusions: RSA should be looked at as a very powerful research instrument and there are many questions suitable for RSA studies.