The lumbar multifidus muscle makes a significant contribution to lumbar spine stability and the restoration of lumbar multifidus function is often the goal of rehabilitation. At present, there are no reliable and valid physical examination procedures available to assess lumbar multifidus function of patients with low back pain. The authors conducted this study with the aim of investigating the interrater reliability and concurrent validity of the multifidus lift test to identify lumbar multifidus dysfunction amongst patients with low back pain. A cross-sectional analysis of reliability and concurrent validity performed in a university outpatient research facility. 32 individuals between the ages of 18 and 60 years with current low back pain and a minimum modified Oswestry disability score of 20%. Study participants were excluded if they reported a history of lumbar spine surgery, lumbar radiculopathy, medical red flags, osteoporosis or had recently been treated with spinal manipulation or trunk stabilization exercises. Concurrent measures of lumbar multifidus muscle function at the L4/L5 and L5/S1 levels were obtained with the multifidus lift test (index test) and real-time ultrasound imaging (reference standard). The interrater reliability of the multifidus lift test was examined by measuring the level of agreement between two blinded examiners. Concurrent validity of the multifidus lift test was investigated by comparing clinicians’ judgements with real-time ultrasound imaging measures of lumbar multifidus function. They found that interrater reliability of the multifidus lift test was substantial to excellent (Κ = 0.75 to 0.81, p ≤ 0.01) and free from errors of bias and prevalence. When performed at L4/L5 or L5/S1, the multifidus lift test demonstrated evidence of concurrent validity through its relationship with the reference standard results at L4/L5 (rbis = 0.59 to 0.73, p ≤ 0.01). The multifidus lift test generally failed to demonstrate a relationship with the reference standard results from the L5/S1 level.
Their results offer preliminary evidence supporting the reliability and validity of the MLT to assess lumbar multifidus function at the L4/L5 spinal level. They concluded that more research examining the measurement properties and utility of this test should be conducted before it can be confidently implemented with patients.