The Nerve Root Sedimentation Sign in transverse magnetic resonance imaging has been shown to discriminate well between selected patients with and without lumbar spinal stenosis (LSS), but the performance of this new test, when used in a broad patient population, is not yet known (Barz et al. 2010).

We conducted a retrospective study of consecutive patients with suspected LSS from 2004–2006, before the sign had been described, to assess its association with health outcomes. Based on clinical and radiological diagnostics, patients had been treated with decompression surgery or conservative treatment (physical therapy, oral pain medication). Changes in the Oswestry Disability Index (ODI) from baseline to 24 month follow-up were compared between Sedimentation Sign positives and negatives in both treatment arms.

Of the 146 included patients (52% female, mean age 59 yrs), 71 underwent surgery. Baseline ODI in this treatment arm was 52%, the sign was positive in 44 patients (mean ODI improvement 25 points) and negative in 27 (ODI improvement 24), with no significant difference between groups. In the 75 patients of the conservative treatment arm, baseline ODI was 44%, the sign was negative in 45 (ODI improvement 17), and positive in 30 (ODI improvement 5). Here a positive sign was associated with a smaller ODI improvement compared with sign negatives (t-test, p=0.003).

This study allowed an unbiased clinical validation of the Sedimentation Sign by avoiding it influencing treatment selection. In the conservative treatment arm a positive sign identifies a group of patients who are less likely to benefit. In these cases, surgery might be effective; however, this needs confirmation in prospective studies.

Most people experience low back pain (LBP) at least once in their lifetime. A minority goes on to develop persistent LBP causing significant socioeconomic costs. Aim of this study was to identify factors that influence the progression of acute to persistent LBP at an early stage (Hilfiker et al. 2007).

Prospective inception cohort study of patients attending a health practitioner for their first episode of acute LBP or recurrent LBP after a pain free period of at least six months. Patients were assessed at baseline addressing occupational and psychological factors as well as pain, disability, quality of life and physical activity, and followed up over six months. Baseline and follow-up questionnaires were based on the recommendations of the Multinational Musculoskeletal Inception Cohort Study (MMICS) Statement (Pincus et al. 2008). Variables were combined to the three indices ‘working condition’, ‘depression and maladaptive cognitions’ and ‘pain and quality of life’.

The index ‘depression and maladaptive cognitions’ comprising of depression, somatisation, a resigned attitude towards the job, fear-avoidance, catastrophizing and negative expectations on return to work was found to be a significant baseline predictor for persistent LBP up to six months (OR 5.1; 95%CI 1.04–25.1). The diagnostic accuracy of the predictor model had a sensitivity of 0.54 and a specificity of 0.90. Positive likelihood ratio was moderate with 5.3, negative likelihood ratio 0.5. Overall predictive accuracy of the model was 81%. The area under the curve in receiver operating characteristic (ROC) analysis of the index was 0.78 (CI95% 0.65–0.92), demonstrating a satisfactory quality of discrimination.

Psychological factors in patients with acute LBP in a primary care setting correlated with a progression to persistent LBP up to six months. The benefit of including factors such as ‘depression and maladaptive cognition’ in screening tools is that these factors can be addressed in primary and secondary prevention.

We compared revision and mortality rates of 4668 patients undergoing primary total hip and knee replacement between 1989 and 2007 at a University Hospital in New Zealand. The mean age at the time of surgery was 69 years (16 to 100). A total of 1175 patients (25%) had died at follow-up at a mean of ten years post-operatively. The mean age of those who died within ten years of surgery was 74.4 years (29 to 97) at time of surgery. No change in comorbidity score or age of the patients receiving joint replacement was noted during the study period. No association of revision or death could be proven with higher comorbidity scoring, grade of surgeon, or patient gender.

We found that patients younger than 50 years at the time of surgery have a greater chance of requiring a revision than of dying, those around 58 years of age have a 50:50 chance of needing a revision, and in those older than 62 years the prosthesis will normally outlast the patient. Patients over 77 years old have a greater than 90% chance of dying than requiring a revision whereas those around 47 years are on average twice as likely to require a revision than die. This information can be used to rationalise the need for long-term surveillance and during the informed consent process.

Posterior lumbar fusion is a frequently performed procedure in spinal surgery. High percentages of good and excellent results are indicated by physicians. On the other hand patient-based outcomes are reported. Little is known about the correlations of these two assessment types. We aimed at their comparison.

The analysis included 1013 patients with degenerative spinal disease or spondylolisthesis from an international spine registry, treated with posterior lumbar fusion. All patients were pre/postop assessed by physician-based McNab criteria (‘excellent’, ‘good’, ‘fair’, ‘poor’). Of these patients, 210 (mean age 61 years; 57% females) were in addition assessed by patient-based Oswestry Disability Index (ODI). The remaining 803 patients (mean age 59 years; 56% females) were assessed by patient-based Core Outcome Measure Index (COMI), including

Visual Analogue Scale (VAS) for back and leg pain as well as verbal self-rating (‘helped a lot’, ‘helped’, ‘helped only little’, ‘didn’t help’, ‘made things worse’). McNab criteria were compared to the Minimal Clinically Important Difference (MCID) in ODI (12.8), in VAS back (1.2) and leg pain (1.6). We investigated the correlations between McNab criteria and these patient-based outcomes.

In the ‘excellent’ group as rated by physicians, the proposed MCID was reached in 83% of patients for ODI, in 69% for VAS back and in 83% for VAS leg pain. All patients said the treatment had ‘helped’ or ‘helped a lot’. In the ‘good’ group 56% (ODI), 66% (back pain) and 86% (leg pain) reached the MCID. 96% of patients perceived the treatment as positive. In the ‘fair’ group 37% (ODI), 55% (back pain) and 63% (leg pain) reached the MCID. 49% had positive treatment considerations. The ‘poor’ group revealed 30% (ODI), 35% (back pain) and 44% (leg pain) of patients with reached MCID. Only 15% rated the treatment as positive.

The Spearman correlation coefficients between McNab criteria on the one hand and ODI, back and leg pain as well as patients’ verbal self-rating on the other hand were 0.57, 0.37, 0.36 and 0.46 respectively.

The comparison of physician and patient-based outcomes showed the highest correlations between McNab criteria and ODI, somewhat weaker correlations with patients’ self-rating and the weakest correlations with back and leg pain. Based on these findings, physicians’ evaluation of patient outcomes can be considered a valuable part of patient assessment, corresponding very well with patients’ perceptions of success or failure of spinal surgery.

Introduction: Dural tears are one of the most frequent type of complication in posterior spinal fusion with little known about their predictors.

Method: Prospective consecutive study with an evidence level 2++ of 42 patients in the international spine registry Spine Tango, who had been treated between 05/2005 and 8/2008 with posterior spinal fusion after opening of the spinal canal. Median age was 62.7 yrs (min 12.5, max 90.5 yrs) with a female to male ratio of 2:1. In 42 of 1575 cases a dural tear occurred being the most frequent type of complication in our study sample. Multiple linear regression was performed on potential predictor-variables of the occurrence of dural tears.

Results: Hospital (p=0.02) and number of segments of fusion (p=0.018) were found to be predictors of the occurrence of dural tears in posterior spinal fusion. Number of fusions per hospital (min 25, max 526) and academic status of hospital had no influence on the rate of dural tears. Fusions of four and more segments showed an increase of the rate of dural tears by three compared to fusions of less than four segments.

Conclusion: Predictors of dural tears in posterior spinal fusion are hospital, independent of number of spinal surgeries and academic status of hospital, and number of segments of fusion. In fusions of four and more segments a threefold higher risk of dural tears in comparison to fusions of less than four segments should be taken into consideration.

Introduction: Posterior lumbar fusion, in many variations, is one of the frequently performed procedures in spinal surgery. High percentages of good and excellent results are indicated by physicians. On the other hand isolated patient-based outcomes are reported. However, little is known about correlation of these two assessment types. We aimed at their comparison.

Methods: The analysis included 567 patients from the international registry ‘Spine Tango’. 453 patients with degenerative disease and posterior lumbar fusion had preop and postop VAS separately indicating back- and leg-pain, surgery and follow up data. Mean age was 57y; female/male ratio was 52% to 48%. Remaining 114 patients with the same diagnoses and treatment had additional preop and postop Oswestry disability indices (ODI). Mean age was 61y; female/male ratio was 55% to 45%.

Physician administered McNab criteria “excellent, good, fair and poor” were compared to ODI, VAS back- and leg pain and to the patients answer describing the outcome of the operation with the following options: helped a lot, helped, helped only little, didn’t help and made things worse. Then the concept of minimum clinically important difference (MCID) was applied

Results: In the “excellent” group ODI-improvement was detected for all patients, the proposed MCID was reached in 90% for ODI. According to this model 85.2% of patients reached MCID for VAS leg pain and 54.1% for VAS back pain. All patient said that the treatment helped or helped a lot

In the “good” group 86% (MCID: 51.7%) of patients improved regarding ODI, 81% (MCID: 65,7%) regarding back and 93% (MCID: 89.4%) regarding leg pain. 99% of patients said that the treatment helped a lot, helped or helped only little.

65% (MCID: 40%) of patients in the “fair” group had improved ODIs. Even in this group 88% of patients perceived the treatment as helping a lot, helping or helping only little.

Moreover in the “poor” group had 60% (MCID: 40%) of patients improved ODIs, 55% (MCID: 40%) alleviated back and 36% (MCID: 30%) reduced leg pain. But only 30% of patient stated that the treatment helped or helped only little.

Spearman correlation coefficients for ODI, VAS back, VAS leg and patient’s verbal statement on overall outcome were 0.42, 0.18, 0.27 and 0.53.

Discussion: ‘Spine Tango’ registry, to date containing more than 13.000 documented surgeries and three times more outcome datasets, provides excellent opportunities for comparison of outcomes. The analysis of patient and physician-based outcomes showed good correlation with the highest correlation coefficient for patient’s verbal statement. With this study we can state that there is strong evidence that physicians evaluation of outcome is very good corresponding with the patients’ perception of success or failure of the analyzed procedure.

Introduction: Lumbar spinal stenosis (LSS) is diagnosed by a history of claudication, clinical investigation, treadmill test, and cross sectional area (CSA) in MRI or CT. Because commonly used radiological findings not always correlate with clinical symptoms, additional parameters with high specificity and sensitivity are needed.

Methods: Prospective study of dorsal lumbar nerve root sedimentation in MRI scans in supine position of 2 groups of 100 consecutive patients each between 01/2007 – 12/2007. Patients in group 1 had non-specific low back pain (LBP), no claudication, and a CSA above 120 mm2 (LBP group); patients in group 2 showed claudication with or without LBP and a CSA below 80 mm2 (LSS group). We excluded patients with a previous spine surgery. In addition to the sedimentation sign, in both groups VAS, ODI, and walking distance in the treadmill test were measured.

Results: The sedimentation sign was positive in 94 patients in the LSS group but in no patient in the LBP group, showing a specificity of 100%, a sensitivity of 94%, and an accuracy of 97%. There was no difference between segmental levels L1 – L5. Walking distance in the LSS group was shorter than in the LBP group (67 m vs. > 1000 m; p< 0.001). There were no significant differences between both groups regarding VAS and ODI.

Conclusion: In patients without LSS during MRI in supine position lumbar nerve roots sediment due to gravity to the dorsal part of the dural sac leading to a positive sedimentation sign. This sedimentation is not observed in patients with LSS. Therefore, a negative sedimentation sign is a predictor of LSS in patients without prior spine surgery with a high specificity and sensitivity. Level S1 and below were excluded in our study because nerve roots S1 and S2 leave the dural sac in a ventral position inhibiting sedimentation to the dorsal part of the dural sac. The sedimentation sign is a reliable additional diagnostic parameter in patients with LSS.

Background: context: Length of hospital stay (LOS) varies widely within patients with posterior spinal fusion. So far there is little evidence on its co-variates.

Purpose: This study examined which co-variates influence LOS in posterior spinal fusion. Study design: Prospective consecutive documentation of hospital based interventions in the international spine registry Spine Tango. Patient sample: Between 05/2005 and 11/2006 data of 3437 patients were documented in the registry. 790 patients with degenerative spinal disease (614) or spondylolisthesis (176), who had been treated with posterior decompression and spinal fusion, were included in this study. Median age was 62.8 yrs (min 13.2 yrs, max 89.8 yrs) with a female to male ratio of 2:1. Median LOS was 11 days (IQR 8–14 d). Outcome measures: LOS was chosen as dependent outcome variable.

Methods: Multiple linear regression was performed on following independent variables: age, gender, main pathology, number of spinal segments of posterior fusion, level of fusion, number of previous spinal surgeries, operation time, clinic (number of fusions, academic status), surgeon credentials, type of fusion (sole fusion, fusion + instrumentation, fusion + instrumentation + cage).

Results: Clinic (p< 0.0001) was found to be a highly significant co-variate for LOS (min 7 d, max 14 d). Number of fusions per clinic (min 25, max 434) and academic status of clinic had no influence on LOS. Further significant covariates were surgeon credentials (surgeons in training: 8.5 d, specialised spine surgeons: 11 d, orthopaedic or neurosurgeons: 12 d; p=0.001), number of spinal segments of posterior fusion (1 segment: 10 d, 2–3 segments: 12 d, 4–5 segments: 12.5 d, > 5 segments: 15 d; p=0.002), and age group (< 50 yrs: 9 d, 50–59 yrs: 11 d, 60–69 yrs: 12 d, ≥70 yrs: 13 d; p=0.01). Borderline significance was found for gender (women: 12 d, men: 10 d; p=0.05). All other variables showed no influence on LOS.

Conclusion: Co-variates of LOS of patients with posterior spinal fusion are clinic, independent of number of spinal surgeries per clinic and academic status of clinic, surgeon credentials, number of segments of fusion, age group, and gender. A short LOS in surgeries performed by surgeons in training is explained by a smaller number of segments of fusions in these procedures. A subgroup analysis on the co-variate clinic should be performed assessing further explanatory variables. However, this goes beyond the possibilities of documentation in a spine registry.

As an example of benchmarking in spinal surgery using Spine Tango, we extracted data on dural tears, one of the most frequent types of complications in posterior spinal fusion. Little is known about their predictors. This study examined which factors predict the occurrence of dural tears in posterior spinal fusion.

Prospective consecutive documentation of hospital based interventions with an evidence level 2++. Between May 2005 and November 2006 data of 3437 patients were documented in the registry. Nine hundred and twenty nine patients, who had been treated with posterior spinal fusion after opening of the spinal canal, were included in this study. Dural tears being the most frequent type of complications in the registry were chosen as dependent outcome variable. Multiple linear regression with stepwise elimination was performed on potential predictor-variables of the occurrence of dural tears. Benchmarking compared the performance of single hospitals with international peers. Median age was 62.7 years (min 12.5, max 90.5 yrs) with a female to male ratio of 2:1. In 18 of 929 cases a dural tear occurred. Hospital (p=0.02) and number of segments of fusion (p=0.018) were found to be predictors of the occurrence of dural tears in posterior spinal fusion. Number of fusions per hospital (min 25, max 526) and academic status of hospital had no influence on the rate of dural tears. Fusions of four and more segments showed an increase of the rate of dural tears by a factor of three compared to fusions of less than four segments. There was no significant difference between fusions of one segment and fusions of two or three segments (1.3 vs. 1.9%) as well as between fusions of four or five segments and fusions of more than five segments (4.6 vs. 4.2%). Differences between hospitals remained when benchmarking dural tears with case mix.

Predictors of dural tears in posterior spinal fusion are

hospital and

In fusions of four and more segments a threefold higher risk of dural tears in comparison to fusions of less than four segments should be taken into consideration.

Posterior lumbar fusion is one of the most frequent procedures in spinal surgery. This study examined which factors predict physician-based outcomes in posterior lumbar fusion within the international spine registry Spine Tango.

This study used prospective consecutive hospital based documentation. Between May 2005 and October 2007 720 patients had been treated with posterior lumbar fusion for degenerative disease or spondylolisthesis. McNab criteria as commonly used physician-based outcomes were chosen as dependent outcome variable. We dichotomised the original McNab criteria combining “excellent” with “good” to “good”, and “fair” with “poor” to “poor”. Multivariate logistic regression was performed on following potential predictor-variables: age, gender, main pathology, number of previous spinal surgeries, number of spinal segments of posterior fusion, operation time, surgeon credentials, follow-up interval.

Median age was 63 years (range 13–90 yrs) with a female to male ratio of 6.3:3.7. Number of previous spinal surgeries (p< 0.001) and follow-up interval (p< 0.001) were found to be predictors of the dichotomised McNab criteria. Patients without previous spinal surgery showed the highest ratio of “good” to “poor” outcome (80.5%:19.5%). This ratio was almost consistently decreasing with the number of previous spinal surgeries to 40%:60% in patients with more than five previous surgeries. At six and twelve-weeks follow-up outcomes were significantly better than after one year, without significant differences between other follow-up intervals. Other examined co-variables showed no influence on the outcomes.

Predictors of physician-based outcomes in posterior lumbar fusion are “number of previous spinal surgeries” and “follow-up interval”. In patients with more than five previous spinal surgeries a higher likelihood of “poor” outcomes should be taken into consideration. A too positive outcome may occur at six or twelve-week’s follow-up.

Introduction: With a life of over five years, Spine Tango can be considered the first truly International Spine Registry. The Swedish Spine Registry has already shown the feasibility of a registry on a national level. But, there is a need for an international spine registry allowing a benchmarking on an international level. Here we demonstrate the genesis of questionnaire development, the constantly increasing activity, and limitations of the International Spine Registry Spine Tango.

Methods: From 2002 until 2007 about 9000 datasets were submitted by 28 hospitals in nine countries worldwide. Three different generations of Spine Tango questionnaires were used for documentation.

Results: To cope with varying international administrative issues and legal requirements of data anonymisation, national Spine Tango modules are necessary. Four national Spine Tango modules are in operation to date, another three modules are in the process of roll-out. Considering all these participants, Spine Tango will soon expand to include data from 52 hospitals in 18 countries. One-fourth of these hospitals are University Hospitals, which are destined to take the lead in the Spine Tango registry as opinion leading hospitals. Although the number of participants is steadily growing, no country is yet represented with a sufficient number of hospitals. Indisputably, a marketing concept is needed. An acquisition of new centres via national spine societies seems an obvious strategic approach. Further limitations of Spine Tango include the low number and short duration of follow-ups and the lack of sufficiently detailed patient based data on subgroup level.

Discussion: Spine Tango has achieved a firm position as international spine registry and with its increasing acceptance it is also gaining importance. The strengths of Spine Tango include a potentially very large network, the participation of a specialized international society and an academic partner with expertise and extensive experience in registry implementation. Data analysis from Spine Tango is possible but complicated by the incompatibility of generations one and two with the more recent generation three. Consequently findings cannot yet be generalized to any specific country or patient population. Nevertheless, the potential benefits of the project for the whole spine community become increasingly visible. In the near future, the established Spine Tango version three with standardised patient based data will make outcome evaluations possible. In parallel to the International Spine Registry Spine Tango, a National Spine Registry in Australia could be set up – comparable to AOA’s National Joint Replacement Registry.

Introduction: As an example of possibilities of Spine Tango we extracted data on dural tears, one of the most frequent types of complications in posterior spinal fusion. Little is known about their predictors. This study examined which factors predict the occurrence of dural tears in posterior spinal fusion.

Methods: Prospective consecutive documentation of hospital based interventions with an evidence level 2++. Between 05/2005 and 11/2006 data of 3437 patients were documented in the registry. 929 patients, who had been treated with posterior spinal fusion after opening of the spinal canal, were included in this study. Median age was 62.7 yrs (min 12.5, max 90.5 yrs) with a female to male ratio of 2:1. In 18 of 929 cases a dural tear occurred. Dural tears being the most frequent type of complications in the registry were chosen as dependent outcome variable (3–6). Multiple linear regression with stepwise elimination was performed on potential predictor-variables of the occurrence of dural tears. Benchmarking compared the performance of single hospitals with international peers.

Results: Hospital (p=0.02) and number of segments of fusion (p=0.018) were found to be predictors of the occurrence of dural tears in posterior spinal fusion. Number of fusions per hospital (min 25, max 526) and academic status of hospital had no influence on the rate of dural tears. Fusions of four and more segments showed an increase of the rate of dural tears by a factor of three compared to fusions of less than four segments. There was no significant difference between fusions of one segment and fusions of two or three segments (1.3 vs. 1.9%) as well as between fusions of four or five segments and fusions of more than five segments (4.6 vs. 4.2%). Differences between hospitals remained when benchmarking dural lesions with case mix.

Discussion: The feasibility of data analysis and benchmarking from the International Spine Registry Spine Tango could be demonstrated. Predictors of dural tears in posterior spinal fusion are

hospital and

In fusions of four and more segments a threefold higher risk of dural tears in comparison to fusions of less than four segments should be taken into consideration. A subgroup analysis on the predictor-variable hospital should be performed assessing further covariates. However, this goes beyond the possibilities of documentation in this international spine registry.

Introduction: Lumbar spinal stenosis is a frequent indication for spinal surgery. The predictive quality of treadmill testing and MRI for diagnostic verification is not yet clearly defined. The aim of our study was to assess correlations between treadmill testing and MRI findings in the lumbar spine.

Methods: Patients with lumbar spinal stenosis who had been admitted for surgical treatment by means of decompression with or without stabilisation were prospectively examined. We included patients with lumbar spinal stenosis as defined by clinical symptoms like low back and/or leg pain, which increased when walking, and by the area of the dural sac examined by MRI. We excluded patients with clinically manifest peripheral arterial disease, polyneuropathy or musculoskeletal impairments compromising the ability to walk. Treadmill tests were performed using the standardized testing protocoll by Deen at a speed of 0.5 m/sec without inclination. After the onset of symptoms (pain, weakness or dysaesthesia), each patient decided when to end the test.

The area of the dural sac and neuroforamina was examined with MRI for the narrowest spinal segment. ODI and VAS were used for clinical assessment.

Results: 25 patients were included with a median age of 67 years (Interquartile range IQR 60–72 yrs). In the narrowest spinal segment the median area of the dural sac was 91mm2 (IQR 67–135 mm2). The median ODI was 66 percent (IQR 64–72 percent). The median walking distance in the treadmill test was 70 m (IQR 30–130 m). The distance reached in the treadmill test correlated with the area of the dural sac (Spearman’s rho=0.53) and ODI (rho=0.51), but not with the area of the neuroforamina and VAS.

Discussion: The treadmill test helps objectifying pre- and postsurgical clinical complaints and verifying a lumbar spinal stenosis by creating a situation of dynamic strain. Moreover, the treadmill test lets the patient experience his own physical limits and enables the examiner to attain a replicable postoperative assessment. The distance reached in the treadmill test predicts the grade of stenosis in MRI but has a limited diagnostic importance for the level of clinical symptoms in lumbar spinal stenosis.

SPINE TANGO is the first International Spine Register. While it has now been fully operational for five years, no results of its collected data have been presented yet. The Swedish Spine Register has already shown that a National Spine Register can generate valid and meaningful data. Here we present data from the first three versions of SPINE TANGO.

From 2002 until 2006 about 6000 datasets were submitted by 25 hospitals worldwide. Descriptive analysis was performed for demographic, surgery, and follow-up data comparing all three versions of SPINE TANGO.

Over the course of its existence the SPINE TANGO data base showed a rise in median patient age from 52.3 years to 58.6 years and an increasing percentage of degenerative disease as main pathology from 60.1% to 71.4 %. Posterior decompression was the most frequent surgical measure. About one third of all patients had follow-ups. Rehabilitation was arranged more frequently, especially home-based and outpatient rehabilitation. The complication rate was decreasing below 10%.

The feasibility of data analysis from the International Spine Register SPINE TANGO could be demonstrated performing descriptive analysis with an evidence level III. In the near future, the meanwhile established SPINE TANGO version 3 with patient based data will make outcome

evaluation possible. This will enable us to present more comprehensive analyses of SPINE TANGO and to make the data base even more beneficial for the whole spine community. In parallel to the International Spine Register SPINE TANGO, a National Spine Register in New Zealand could be set up – comparable to NZOA’s National Joint Register.

Background context: Surgical treatment of lumbar spinal stenosis is one of the most frequent procedures in spinal surgery. Nevertheless, the predictive quality of instruments like treadmill test and MRI has not yet been clearly defined for the lumbar spinal stenosis.

Purpose: Objective of this study was to verify correlations between treadmill test and MRI findings in the narrowest spinal segment.

Methods: In a prospective study (EBM-level 3) 25 patients with inpatient treatment for lumbar spinal stenosis were investigated between 01/2005 and 06/2005. Exclusion criteria were a reduced walking capacity for other reasons (e.g. gonarthrosis). Treadmill tests were performed following the protocol by Deen. Patients estimated their maximum walking distance before performing the tests. Area of the dural sac, area of the neuroforamina and disc height at the dorsal margin were examined by MRI for the narrowest spinal segment. VAS and ODI were used as clinical assessment instruments.

Outcome Measures: The median age of patients was 67 yrs (IQR 58–73 yrs) with 44 % females. The median distance reached in the treadmill test was 70 m (IQR 30–135 m), the median estimated maximum walking distance 200 m (IQR 100–300 m). In the narrowest spinal segment the median area of the dural sac was 91 mm2 (IQR 65–143 mm2), the median area of the neuroforamina 43 mm2 (IQR 36–51 mm2) and the median disc height 1,4 mm (IQR 0,9–2,5 mm). The median VAS was 7 (IQR 6,5–8) and the median ODI 33 (IQR 32–37).

Results: The distance reached in the treadmill test correlated with the maximum walking distance estimated by the patients (Spearman’s rho=0,62, p=0,001), area of the dural sac (rho=0,54, p=0,006) and disc height (rho=0,45, p=0,03), but not with area of the neuroforamina and VAS. VAS correlated with the disc height (rho=−0,6, p=0,002), but with no other MRI findings.

Conclusions: The distance reached in the treadmill test and MRI findings in the narrowest spinal segment predict the level of clinical symptoms. Possible reasons for the slightly limited predictive quality of MRI findings are that this study did not regard the time of development of the stenosis, that effects of multilevel stenosis were not considered, and that MRI findings in lying position without lordosis might differ from findings in standing position. However, the treadmill test is a valid and highly practicable pre-surgery diagnostic instrument in lumbar spinal stenosis.

Introduction: Studies about the influence of patient characteristics on mechanical socket failure in THA apply different methodologies and reveal inconclusive results. In addition the fixation mode has rarely been in the focus of investigation.

Methods: We conducted a two-arm matched pairs case-control study assessing the influence of patient characteristics sex, age, weight, BMI, diagnosis, and activity level (Charnley classification) on the odds for mechanical socket loosening. The cemented and uncemented fixation mode was analyzed separately.

Results: 299 cases and 986 controls were included in the cemented study arm and 510 cases and 3000 controls in the uncemented arm. Women had reduced loosening odds for the cemented (OR=0.59, p=0.0024) and uncemented (OR=0.63, p=0.0001) fixation compared to men (OR=1). Each additional year the intervention was postponed reduced the loosening odds by about 2 % for cemented (OR=0.98, p=0.017) and uncemented (OR=0.98, p=0.0002) sockets. In cemented sockets the weight group of 73–82 kg had lower loosening odds (OR=0.63, p=0.017) than the lighter (OR> 0.92) and heavier (OR> 1.1) weight groups. There were no significant effects of weight in the uncemented group. In contrast, obese patients (BMI> 30) with uncemented sockets displayed elevated loosening odds (OR=1.41, p=0.034) compared to an insignificant effect in the cemented arm. Osteonecrosis was the only main pathology revealing elevated loosening odds (OR=1.27, p=0.049) but only in cemented sockets. The Charnley classification as an indirect proxy of activity revealed changing and insignificant effects.

Conclusions: Female sex and a delayed intervention have similarly protective effects on the odds for cemented and uncemented socket loosening. Whilst a certain body weight range has a significantly protective effect in cemented sockets the more important finding is the significantly increased risk for uncemented socket loosening in obese patients. Patients with osteonecrosis are the only etiologic group at a significantly increase risk for socket loosening, but only with a cemented fixation. The Charnley classification as a surrogate for activity level had no influence on loosening risks in either socket fixation mode. Level of Evidence: Level III (case-control study)

Introduction: Lumbar fusion is one of the most frequently recommended treatments in spinal surgery, whereas ALIF and PLF are discussed controversially. This prospective and consecutive study examined if complications and rehabilitation differed between patients with a degenerated lumbar spine, who had been treated with ALIF or PLF.

Methods: Between 04/2002 and 12/2005 clinical data of 39 patients, who were treated with ALIF, and of 296 patients, who received PLF, were submitted to the European Spine Register SSE Spine Tango. Complications and rehabilitation process were documented after a median follow-up time of 9 weeks (IQR 8–24 weeks). Analysis was performed with non-parametric tests. The study corresponds with an EBM-level 3.

Results: The median age of patients with ALIF was 56 years (IQR 37-66 yrs) vs. 64 yrs in the PLF group (IQR 54–72 yrs) with a male to female ratio 10:29 vs. 108:188.

Patients after ALIF and PLF had an even complication rate (5/39 vs. 26/296, p = 0,41). The types of complications in the ALIF group were less severe (sensory and motoric disturbance vs. implant failure and implant malposition). All five patients needing reintervention belonged to the PLF group. Three quarters of all patients underwent rehabilitation. The proportion of patients with outpatient rehabilitation was higher in the ALIF group (14/39 vs. 50/296 patients, p = 0,05).

Conclusions: Patients with degenerative lumbar spine disease have a less severe type of complications after ALIF than after PLF, whereas the complication rate is even. Concerning the higher proportion of patients with outpatient rehabilitation in the ALIF group, one has to consider their lower age compared with patients in the PLF group. Except for the severeness of complications and the proportion of outpatient rehabilitation one cannot conclude an advantage of either of the two surgical methods.