It has been proposed that the amount of energy transferred to the bone during a high velocity projectile injury determines the extent of bony injury. We studied the validity of this theory Fresh rear skeletally mature deer femurs were subjected to progressively increasing velocity projectile injuries within a pneumatic ballistic chamber with non-deforming steel spheres capturing the energy transferred. Analysis of fracture severity was performed including micro computer tomography analysis of micro-fractures. The effect of projectile caliber size was then analyzed.

Characteristic fractures patterns were observed with fracture lines extending radially from the impact site, often propagating longitudinally along the sample. It was found that a greater energy transfer resulted in more severe fracture for a given projectile. However, fractures of differing severity were produced by different projectiles for similar energy transfer. Neither specific energy transfer nor energy density could explain this phenomenon.

Although energy transfer plays a role in ballistic fracture, it is not the sole determinant. Other factors such as contact surface area, projectile mass and angle of impact may need to be considered.

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.