Potential Reasons For Unsatisfactory Outcome

A certain number of patients who, despite successful stabilization of previously unstable sacroiliac joints, either with conservative treatment or percutaneous fixation with or without supplemental fusion, continue to experience pain and dysfunction. This is largely due to associated conditions, and not due to the surgical technique itself.

Sacroiliac joint dysfunction can occur as an isolated condition or in association with other spinal disorders. Torsion injuries can cause damage to the disc annulus, facet joints, laminae, and ligaments, as well as the sacroiliac joint.

    • Facet Joint:
      Torsion or axial rotation causes the facets to flex and laterally side bend towards the site of the rotation, crushing the facet articular surfaces on the rotational side and distracting the capsule with tearing or avulsion on the side opposite the rotation.
    • Nerve Root:
      The lateral portion of the facet joint is long and slender and is therefore easily deformed. Torsion causes facet impingement on the torsion side. Distraction on the contralateral side can stretch the nerve root. Thus, neural arch deformation can cause bilateral nerve root entrapment.
    • Discs:
      Torsion cause annular tears, which can weaken the annulus leading to bulge or herniation of the nucleus pulposus. The iliolumbar ligament can become taut due to subluxation of the SIJ. Its fibers are attached to the transverse process at L4. Chronic tension can lead to bulging of the disc. It is not uncommon to see an L4-5 annular bulge on the MRI in patients with chronic instability.
    • Effect on Muscle:
      A physician of physical medicine famous for studies associated with joint malalignment (Janda) has pointed out that, as the result of articular dysfunction, postural muscles become facilitated and, therefore, tighten and phasic muscles become inhibited and, therefore weaker. With longstanding dysfunction, anatomic changes of the muscle bellies take place that are irreversible. The piriformis is the most adversely affected muscle in chronic SIJ instability (piriformis syndrome). Pelvic wall muscle spasm or contraction can lead to pelvic wall dysfunction. The muscles that may be affected include the iliopsoas, hamstrings, adductors and Gluteus Maximus, as well as the quadratus lumborum and tensor fasciae late.
    • Piriformis Sciatica:
      The piriformis muscle is frequently associated with SIJ dysfunction. The diagnosis is usually made with nerve study to check H-wave in neutral hip position and in flexed, adducted and internal rotation position. Comparison should be made bilaterally in this manner. If positive, then the piriformis can be detached at its insertion into the greater trochanter area, freeing up the sciatic nerve and allowing for the muscle to slide. Symptoms of Piriformis Syndrome: Buttock pain that radiates into the hip and lateral aspect of the leg. As the piriformis syndrome worsens the pain can radiate down the back and side of the leg to the foot. Symptoms are worsened by walking and sitting.
    • Effect on Nerves:
      Due to longstanding spasm or secondary fibrosis, the chronically-shortened piriformis can entrap neurovascular status that accompany it through the greater sciatic foramen (superior and inferior gluteal nerves, the sciatic nerve and the pudendal nerve.) The lateral femoral cutaneous nerve passes just medial to the anterior sacroiliac spine and can be injured as it passes from the pelvis to the thigh by changes in anatomic position associated with sacroiliac subluxation (meralgia paresthetic).
    • Public Symphysis Instability:
      With chronic instability, the contralateral SIJ, as well as the pubic symphysis may destabilies.