Objective: Using rehabilitation ultrasonography imaging (RUSI) is widely growing in the physiotherapy clinics of developed countries. Due to this new application, it is necessary to consider the repeatability of this new technique by novice physiotherapists and applied methods to measure the muscle size. This study has been designed to investigate the intrarater reliability and also the relation between multiplying linear dimension (MLD) and cross sectional area (CSA) measurements to evaluate the size of lumbar multifidus muscles by novice physiotherapists.

Materials & Methods: Ultrasonographic images of L2 to L5 lumbar multifidus muscles of sixty healthy female volunteer were taken bilaterally. Then, the size of multifidus was calculated by CSA and also by MLD methods for all level of lumbar region. The repeatability of data was also evaluated in a parallel study on a group of sixteen healthy female subjects in two different evaluation sessions.

Results: Significant intrarater reliability was found between recoded data from two different evaluation sessions for both CSA and MLD measurements (ICC= 0.81 to 0.98). The results also indicated a significant relation was also found between CSA and MLD methods to evaluate the size of multifidus muscles for the L2 to L5 lumbar vertebra (r=0.89 to 0.97, P<0.0001).

Conclusion: Our findings confirm that using RUSI and the MLD method are efficient methods to evaluate the size and any other change in the lumbar multifidus muscle, during rehabilitation protocols.