290 - Neuromuscular Activity during Gait in Patients with Sacroiliac Joint P...

General Session: Diagnostic Imaging

Presented by: J. Cox


R. Haddas(1), J. Cox(1), S. Kutz(2), R. Rashbaum(2)

(1) Texas Back Institute, Research Foundation, Plano, TX, United States
(2) Texas Back Institute, Plano, TX, United States


Background: The sacroiliac (SI) joint is cited as the source of pain in 15% to 30% of patients presenting with low back pain. Without previous lumbar fusion appearance for situation that indicates up to 47% in those patients. However, the diagnosis of SI joint dysfunction is difficult to make because presenting symptoms can be similar to other etiologies of low back pain. Several physical exam maneuvers have been described in an effort to distinguish sacroiliac joint pain from other causes but a gold standard is lacking, illustrating the need for a deeper understanding of SI joint pathology. Knowledge of neuromuscular adaptations that occur in patients with SI joint dysfunction is scarce and may improve our understanding of the disease and have implications on rehabilitation for these patients.

Purpose: The purpose of this study was to determine neuromuscular activity during gait in patients diagnosed with sacroiliac joint pain compared to controls.

Study Design: A non-randomized, prospective, concurrent control cohort study.

Patient Sample: Eleven patients with symptomatic SI joint pain who have been deemed appropriate surgical candidates compared with 20 healthy controls.

Outcome Measures: Spine and lower extremity of integrated electromyography (iEMG) and time to max EMG activity.

Methods: Clinical gait analysis was performed the week before surgery. External Oblique (EO), Multifidus (Mf) at the level of L5, Erector Spinae (ES) at the level of L1, Gluteus Maximus (GM), Rectus Femoris (RF), Semitendinosus (ST), Tibialis Anterior (TA), and Medial Gastrocnemius (MG) neuromuscular activity were measured and recorded during the gait analysis session. Each subject performed a series of over-ground gait trials at a comfortable self-selected speed. iEMG activity is a graphic representation of the sum total EMG activity over a defined period of time. One-way ANOVA analysis was used for the statistical analysis.

Results: Compared to controls, patients with SI pain demonstrated significantly less activation of the EO (3.43±2.3 vs 0.35±0.1mV; p=0.044), GM (2.76±4.1 vs 0.33±0.1mV; p=0.050), and Mf (3.40±4.2 vs 0.57±0.4mV; p=0.049). Time to max EMG muscle activity was significantly longer in the EO (0.03±0.0s vs 0.01±0.0s; p=0.050), ES (0.01±0.0s vs 0.00±0.0s; p=0.048) and the ST (0.03±0.0s vs 0.02±0.0s; p=0.046) in patients with SI joint pain compared to healthy controls.

Conclusions: The sacroiliac joint is responsible for load transfer from the pelvis to the spine, and does so through a complex interaction of static and dynamic stabilizers. Dysfunction in the SI joint often causes pain and limits one's ability to stand, walk and sit. Impaired anticipatory and compensatory motor function is beginning to garner attention as an underlying contributor to SI joint pain, yet there are few studies characterize individual muscle function and time-to-max EMG in patients with this disease. This study found impairment in activation and time-to-max EMG for several trunk and lower extremity muscles in patients with SI joint pain, suggesting there is a pain avoidance mechanism leading to poor neuromuscular function and coordination. In addition to our findings, this study contributes to existing knowledge on EMG muscle activity in patients with SI joint pain and will be useful in future studies investigating neuromuscular function of patients with SI joint pain after both nonsurgical and surgical treatment options.