Interrater and Intrarater Reliability of Transverse Abdominal and Lumbar Multifidus Muscle Thickness in Subjects With and Without Low Back Pain

Randomized clinical trial. Compare outcomes of patients with low back pain receiving treatments matched or unmatched to their subgrouping based on initial clinical presentation. Patients with "nonspecific" low back pain are often viewed as a homogeneous group, equally likely to respond to any particular intervention. Others have proposed methods for subgrouping patients as a means for determining the treatment most likely to benefit patients with particular characteristics. Patients with low back pain of less than 90 days' duration referred to physical therapy were examined before treatment and classified into one of three subgroups based on the type of treatment believed most likely to benefit the patient (manipulation, stabilization exercise, or specific exercise). Patients were randomly assigned to receive manipulation, stabilization exercises, or specific exercise treatment during a 4-week treatment period. Disability was assessed in the short-term (4 weeks) and long-term (1 year) using the Oswestry. Comparisons were made between patients receiving treatment matched to their subgroup, versus those receiving unmatched treatment. A total of 123 patients participated (mean age, 37.7 +/- 10.7 years; 45% female). Patients receiving matched treatments experienced greater short- and long-term reductions in disability than those receiving unmatched treatments. After 4 weeks, the difference favoring the matched treatment group was 6.6 Oswestry points (95% CI, 0.70-12.5), and at long-term follow-up the difference was 8.3 points (95% CI, 2.5-14.1). Compliers-only analysis of long-term outcomes yielded a similar result. Nonspecific low back pain should not be viewed as a homogenous condition. Outcomes can be improved when subgrouping is used to guide treatment decision-making.

Decreases in the size of the multifidus muscle have been consistently documented in people with low back pain. Recently, ultrasound imaging techniques have been used to measure contraction size of the multifidus muscle, via comparison of the thickness of the muscle at rest and on contraction. The aim of this study was to compare both the size (cross-sectional area, CSA) and the ability to voluntarily perform an isometric contraction of the multifidus muscle at four vertebral levels in 34 subjects with and without chronic low back pain (CLBP). Ultrasound imaging was used for assessments, conducted by independent examiners. Results showed a significantly smaller CSA of the multifidus muscle for the subjects in the CLBP group compared with subjects from the healthy group at the L5 vertebral level (F=29.1, p=0.001) and a significantly smaller percent thickness contraction for subjects of the CLBP group at the same vertebral level (F=6.6, p=0.02). This result was not present at other vertebral levels (p>0.05). The results of this study support previous findings that the pattern of multifidus muscle atrophy in CLBP patients is localized rather than generalized but also provided evidence of a corresponding reduced ability to voluntarily contract the atrophied muscle.

Randomized controlled trial among patients with low back pain (LBP). (1) Determine the reliability of real-time ultrasound imaging for assessing activation of the lateral abdominal muscles; (2) characterize the extent to which the abdominal drawing-in maneuver (ADIM) results in preferential activation of the transverse abdominis (TrA); and (3) determine if ultrasound biofeedback improves short-term performance of the ADIM in patients with LBP. Ultrasound imaging is reportedly useful for measuring and training patients to preferentially activate the TrA muscle. However, research to support these claims is limited. Thirty patients with LBP referred for lumbar stabilization training were randomized to receive either traditional training (n = 15) or traditional training with biofeedback (n = 15). Ultrasound imaging was used to measure changes in thickness of the lateral abdominal muscles. Differences in preferential changes in muscle thickness of the TrA between groups and across time were assessed using analysis of variance. Intrarater reliability measuring lateral abdominal muscle thickness exceeded 0.93. On average, patients in both groups demonstrated a 2-fold increase in the thickness of the TrA during the ADIM. Performance of the ADIM did not differ between the groups. These data provide construct validity for the notion that the ADIM results in preferential activation of the TrA in patients with LBP. Although, the addition of biofeedback did not enhance the ability to perform the ADIM at a short-term follow-up, our data suggest a possible ceiling effect or an insufficient training stimulus. Further research is necessary to determine if there is a subgroup of patients with LBP who may benefit from biofeedback.