Correction of leg-length discrepancy among meat cutters with low back pain: a randomized controlled trial.

BACKGROUND: The etiology of non-specific low back pain (LBP) is complex and not well understood. LBP is common and causes a remarkable health burden worldwide. Leg-length discrepancy (LLD) is potentially a risk factor for development of LBP, although this relationship has been questioned. Yet only one randomized controlled study (RCT) has been performed. The objective of our study was to evaluate the effect of insoles with leg-length discrepancy (LLD) correction compared to insoles without LLD correction among meat cutters in a RCT-design. METHODS: The study population consisted 387 meat cutters who were over 35 years old and had been working 10 years or more. The LLD measurement was done by a laser ultrasound technique. All workers with an LLD of at least 5 mm and an LBP intensity of at least 2 on a 10-cm Visual Analog Scale were eligible. The LLD of all the participants in the intervention group was corrected 70%, which means that if the LLD was for example 10 mm the correction was 7 mm. The insoles were used at work for eight hours per day. The control group had insoles without LLD correction. The primary outcome was between-group difference in LBP intensity. Secondary outcomes included sciatic pain intensity, disability (Roland Morris), RAND-36, the Oswestry Disability Index, physician visits and days on sick leave over the first year. We used a repeated measures regression analysis with adjustments for age, gender and BMI. The hurdle model was used for days on sick leave. RESULTS: In all, 169 workers were invited and 114 (67%) responded. Of them, 42 were eligible and were randomized to the intervention (n = 20) or control group (n = 22). The workers in the intervention group had a higher improvement in LBP intensity (- 2.6; 95% confidence intervals - 3.7 - - 1.4), intensity of sciatic pain (- 2.3; - 3.4 - - 1.07) and RAND-36 physical functioning (9.6; 1.6-17.6) and a lesser likelihood of sick leaves (OR -3.7; - 7.2 - -0.2). CONCLUSIONS: Correction of LLD with insoles was an effective intervention among workers with LBP and a standing job. TRIAL REGISTRATION: ISRCTN11898558 . Registration date 11. Feb 2011. BioMed Central Ltd.

Leg-length discrepancy is associated with low back pain among those who must stand while working.

BACKGROUND: Some studies suggest that leg length discrepancy (LLD) is associated with low back pain (LBP) but many have not found such an association leading to conflicting evidence on the role of LLD in LBP. METHODS: The study population consisted of meat cutters with a standing job and customer service workers with a sedentary job from Atria Suomi Ltd (Nurmo, Finland) who were at least 35 years old and had been working in their jobs for at least 10 years. Leg length of each participant was measured with a laser range meter fixed in a rod, which was holding the scanning head of the ultrasound apparatus. Association of the intensity of LBP (10-cm Visual Analog Scale) with LLD was analysed by linear regression model, while the hurdle model was used in analysing the association of number of days with LBP and days on sick leave during the past year. Associations were adjusted by gender, age, BMI, smoking, depressive feelings and type of work (standing or sedentary job). RESULTS: The final study population consisted of 114 meat cutters (26 females and 88 males) and 34 customer service workers (30 females and four males). Forty-nine percent of the meat cutters and 44% of the customer service workers had LLD of at least 6 mm, while 16% and 15%, respectively, had LLD of at least 11 mm. In the whole study population, LLD of 6 mm or more was associated with higher intensity of LBP and number of days with LBP. In the stratified analysis, both intensity of LBP and number of days of LBP were associated with LLD among meat cutters but not among customer service workers. The sick leaves during past year were slightly longer among those with LLD 10 mm or more, but the differences were not statistically significant. CONCLUSIONS: LLD, measured with a laser range meter, was associated with intensity of LBP and self-reported days with LBP during the past year among meat cutters engaged in standing work. TRIAL REGISTRATION: ISRCTN11898558--The role of leg length discrepancy in low back pain.

Measurement of leg-length discrepancy using laser-based ultrasound method.

BACKGROUND: The evidence on the role of leg-length discrepancy (LLD) in low back pain (LBP) is contradictory, possibly due to the diversity of measurement methods. PURPOSE: To assess the reliability of a laser-based ultrasound method and its agreement with the radiographic method. MATERIAL AND METHODS: The measurement device consisted of a laser measure fixed to a rod holding the scanning head of the ultrasound and could be moved automatically by a linear actuator. The reliability of the measurement was evaluated using 20 healthy voluntary subjects with no known previous LLD (90% women, mean age 23 years). We assessed the agreement of the ultrasound method with a radiographic LLD measurement using 19 voluntary patients (95% men, mean age 38 years), who had had radiographic LLD measurements taken during the previous year. We used intraclass correlation co-efficients (ICC) and Bland & Altman analysis in the statistical analysis. RESULTS: The ICC value for agreement between methods was 0.97 (95% confidence intervals [CI] 0.93-0.99) indicating almost perfect agreement. The ICC values for both raters indicated almost perfect agreement between repeated measurements (ICC 0.996 and 0.994, respectively). In the Bland and Altman analysis, the mean difference was close to zero (0.56 mm and 0.40 mm), indicating minimal systematic error. CONCLUSION: The ultrasound-laser technique is quick and easy to perform. Both reliability and agreement with the radiographic method are excellent. The ultrasound measurement is non-invasive and therefore a potential alternative to radiographic methods in the evaluation of LLD.