Can Correcting LLD Reduce Low Back Pain? Insights from a Randomized Controlled Trial

Low back pain (LBP) is one of the most common and costly health problems worldwide, affecting millions of people and leading to significant loss of productivity. Its causes are complex and multifaceted, making identifying specific risk factors and treatment approaches challenging. Among the potential contributors to LBP is a leg-length discrepancy (LLD). In this condition, one leg is shorter than the other, leading to postural imbalances and uneven stress on the spine. However, the link between LLD and LBP has been the subject of debate.

A recent randomized controlled trial (RCT) conducted by Dr Satu Rannisto offers new insights into this issue. The study focused on a group of meat cutters—individuals whose job demands long hours of standing and physical exertion—examining whether correcting LLD with insoles could reduce LBP and improve their overall physical function. This blog post explores the study’s findings and their implications for managing LBP among individuals with LLD.

Study Overview: Investigating the Role of LLD in Low Back Pain

The researchers designed the study to address a critical question:

Does correcting LLD with insoles alleviate LBP compared to regular insoles without LLD correction?

The study included 114 meat cutters over the age of 35 who had worked in the industry for more than 10 years. These participants were ideal subjects because their jobs involved long periods of standing and physical labor, both of which could exacerbate LBP. Importantly, all participants had a measurable LLD of at least 5 mm, and their LBP intensity was at least 2 on a 10-cm Visual Analog Scale (VAS). LLD was measured using a laser ultrasound technique, a method known for its accuracy in assessing leg length.

Participants were divided into two groups:

1. Intervention group: Received insoles that corrected 70% of their LLD. For instance, if a participant had a 10-mm discrepancy, their insoles provided a 7-mm correction.
2. Control group: Received insoles that did not correct the LLD.

Both groups used their respective insoles for eight hours per day during work for the duration of the study.

Key Outcomes and Measures

The primary outcome of the study was the difference in LBP intensity between the intervention and control groups. Secondary outcomes included:

• Intensity of sciatic pain (pain radiating along the sciatic nerve, often caused by spinal issues).
• Physical function, measured by the RAND-36 health survey.
• Disability levels were assessed using the Roland Morris Disability Questionnaire and the Oswestry Disability Index.
• Number of physician visits.
• Days of sick leave taken due to back pain or related issues.

Results: Does LLD Correction Make a Difference?

The study found significant improvements in the intervention group, who received the LLD-correcting insoles, compared to the control group. Here are the key findings:

1. Reduction in Low Back Pain: The intervention group experienced a notable reduction in LBP intensity. The difference in LBP intensity between the intervention and control groups was -2.6 points on the VAS, with a 95% confidence interval (CI) ranging from -3.7 to -1.4. This suggests a significant decrease in LBP for those who received LLD correction.
2. Improvement in Sciatic Pain: Participants in the intervention group also reported a significant reduction in sciatic pain intensity, with a -2.3 point difference (CI: -3.4 to -1.07). This finding is particularly important, as sciatic pain can be a debilitating symptom often associated with spinal misalignment.
3. Enhanced Physical Functioning: According to the RAND-36 physical functioning scores, the intervention group showed a 9.6-point improvement (CI: 1.6 to 17.6). This suggests that correcting LLD not only alleviated pain but also improved the participants’ ability to perform daily activities and physical tasks.
4. Fewer Sick Leaves: One of the most striking findings was the lower likelihood of taking sick leave due to LBP in the intervention group. The odds ratio (OR) for sick leave was -3.7 (CI: -7.2 to -0.2), indicating that those with corrected LLD were significantly less likely to take time off work for back-related issues.

What Do These Findings Mean?

The results of this study provide strong evidence that correcting LLD can be an effective strategy for reducing LBP, improving physical function, and decreasing the likelihood of sick leave in individuals with LLD. The intervention group’s reduction in both LBP and sciatic pain, coupled with improved physical functioning, underscores the importance of addressing even small discrepancies in leg length.

Moreover, the fact that participants who had their LLD corrected were less likely to take sick leave is particularly significant for employers and occupational health professionals. Chronic LBP is a leading cause of absenteeism, and reducing the need for sick leave could result in substantial cost savings and improved productivity.

Why Meat Cutters?

The study focused on meat cutters, a group whose work involves long hours of standing and repetitive motions, often in physically demanding conditions. This makes them particularly susceptible to musculoskeletal issues like LBP. The choice of this occupation highlights the relevance of LLD correction in physically demanding jobs, but the findings could have broader implications for other industries as well.

Individuals in jobs that require prolonged standing, such as healthcare workers, factory workers, and retail employees, could also benefit from LLD correction if they suffer from LBP. This research suggests that LLD correction through customized insoles should be considered in occupational health assessments, particularly for workers with chronic LBP and measurable leg-length discrepancies.

Practical Implications: Should You Consider LLD Correction?

If you suffer from chronic LBP and suspect that leg-length discrepancy might be a contributing factor, it may be worth discussing LLD correction with your healthcare provider. While insoles with LLD correction are a relatively simple intervention, this study suggests that they can lead to significant improvements in pain and physical function.

For employers and occupational health professionals, ensuring that workers with LBP receive proper assessments for LLD and are provided with corrective insoles could help reduce absenteeism and improve overall job performance.

The study by Rannisto provides compelling evidence that correcting leg-length discrepancies can be an effective intervention for reducing LBP, particularly among individuals in physically demanding jobs like meat cutting. By improving both LBP and physical function, LLD correction offers a promising approach to managing chronic pain and enhancing the quality of life for those affected by this common condition.

If you work in a physically demanding job and suffer from LBP, consider discussing the possibility of LLD correction with your healthcare provider. It may be the key to relieving your pain and getting back to your best self.