Purpose To examine whether unilateral multifidus damage could promote degeneration at the L5-6 facet joint (FJ) and compensatory changes in lumbo-pelvic muscles in rats. Methods 12 facet clamp, 12 facet sham and 7 control rats were studied. Facet clamp and sham animals had the left L5-6 FJ exposed, and the clamp group had a mild compressive clamp applied using hemostatic forceps to model post-traumatic arthritis. Both groups then had the left multifidus detached from the L1-L6 spinous processes. Animals were euthanized 28 days post-surgery. Muscle mass and fascicle length were evaluated bilaterally for the paraspinal muscles, gluteal muscles and biceps femoris. Intra-muscular collagen of the paraspinal muscles was measured histologically. FJ transverse plane angles were measured from micro-computed tomography scans. L5-6 FJ degeneration was evaluated through the 24-point OARSI scale. Results Differences, compared to control, were observed in the detached multifidus from both facet clamp and sham groups; namely decreased mass and fascicle length and increased collagen content. However, no between group differences were found for any other muscle. Further, mild FJ degeneration was more prevalent in the groups that had experienced multifidus injury but was not exacerbated by the mild compressive clamping of the FJ. Conclusion Unilateral multifidus injury with or without FJ compressive clamping does not have a clear impact on the characteristics of surrounding spinal musculature within 28 days post-surgery in rats. Mild FJ degeneration was present in some animals from all three groups, and the impact of multifidus injury on this degeneration is inconclusive.

Sacroiliac joint pain is often interpreted by healthcare practitioners as non-specific pain in the lower back region. This has resulted in many cases of sacroiliac joint pain being misdiagnosed as general chronic low back pain, which has led to large gaps in the knowledge regarding its exact causes and manifestation. The pain is theorized to develop because of the loss of form and/or force closure leading to destabilization and sacroiliac joint dysfunction. Current diagnostic tests include pain provocation tests and intra-articular injections. The intra-articular injections may exclude individuals with extra-articular pain, so more inclusive testing should be considered for use in clinical practice such as range of motion assessment or pubic symphysis analysis. Recent literature does not support the use of present treatments by healthcare practitioners as the therapies lack well designed studies to confirm their efficacy, are extremely invasive, or have minimal symptom management capabilities. Additional research into current and new treatment strategies needs to be done to determine their efficacy in managing this condition. Overall, the development of an animal model of the condition is recommended to better evaluate and improve the diagnosis and treatment of sacroiliac joint pain.