Differentiating Buttock Pain and Sacroiliac Joint Disorders
What Is Causing the Pain?
The diagnosis of Gluteal or buttock pain is complicated due to the overlapping symptoms of many conditions such as :
- Radicular pain from Lumbar spine origin
- Sciatic nerve entrapment
- Obturator internus/gemellus syndrome
- Piriformis Syndrome
- Quadratus femoris/ischiofemoral pathology
- Problems at the hamstrings
- Gluteal muscles disorders
The differential diagnosis of pain and dysfunction a challenging task due to the complicated anatomy of the Sacroiliac joint, the Lumbar spine and the buttock area. The diagnosis is even challenged more by the inconsistency of MRI findings and imaging with the symptoms leading to misdiagnosing the conditions. Using subjective assessment measures and special tests can give an idea of the symptoms but without specifying the source of the pain. Up to this day, there are no fixed guidelines for the diagnosis of buttock pain.
Chronicity of symptoms could be a result of biopsychological factors but shouldn't rule out structural pathology. The development of chronic pain might have been the result of catastrophisation and fear-avoidance as a result of a missed primary structural pain. This can contribute to the difficulty in determining the cause of the dysfunction and pain.
The Sacroiliac joint is the joint connection between the spine and the pelvis formed by the fusion of the three bones of the pelvis: the ilium, ischium, and pubic bone. The sacroiliac joint has different functions:
- Load transfer between the spine and the lower extremities
- Shock absorption
- Converts torque from the lower extremities into the rest of the body.
This region is surrounded by and covered with the dorsal sacral nerve, the iliolumbar ligament, the dorsal sacral ligaments, the erector spinae fascia, which is part of the thoracolumbar fascia and makes palpating specific structures difficult.
The subgluteal space is located between the middle and deep gluteal aponeurosis layers. It contains:
- the Superior/Inferior gluteal nerves
- Blood vessels
- Sacrotuberous/sacrospinous ligaments
- Sciatic nerve
The piriformis muscle is innervated by the branches of the L5, S1, and S2 spinal nerves.
The sciatic nerve has a complicated relationship with the piriformis muscle, passing above, below and through the muscle before and after dividing.
Ruling Out the Lumbar Spine
Buttock pain can be caused by a referred pain from the lumbar spine in the respective dermatome, A study  by Eubanks reported significant improvement in buttock pain following facet joint block.
Red Flags are serious pathologies and should be spotted on the first contact.
Spondyloarthropathies and other inflammatory conditions at the lumbar spine level could possibly refer pain to the buttock area. Patients with Ankylosing spondylitis or Reiter's syndrome may present with inflammatory bowel diseases, such as Diverticulitis or Chrohn's disease, prolonged severe morning stiffness, bilateral enthesopathies such as Achilles tendinopathy or Plantar fasciitis..
Gynaecological problems, potential infectious diseases, possible malignancies and patients not responding to physiotherapy management can possibly reflect the presence of serious pathologies.
This table is adapted from a study by Zibis  on the characteristics and physical examination of Low Back Pain:
Ruling Out the Sacroiliac Joint
Sacroiliac dysfunction.is defined as Any pain from the sacroiliac joints or the surrounding myofascial, nerve or neural structures, connective tissues and ligament structure. It is known to present individuals with lumbar pain of with an incidence rate of 13%-48%, more commonly in females.
The following structures can be responsible for provoking posterior hip pain:
- Thoracolumbar fascia
- Sacroiliac joint
- Gluteus max
- Gluteus minimus
- Obturator Externus and Internus
- Gemelli's Superior and Inferior
- Ischio-gluteal bursa
- Ligaments such as: the long dorsal ligament, sacrotuberous ligament, sacrospinous ligament
Sacroiliac Joint pain could start gradually or suddenly. Gradual pain can result from maladaptive postures, seronegative spondyloarthropathies, osteoarthritis, pregnancy-related pain. Sudden onset develops due to sudden movement, strain or trauma, for example, missing a step or unilateral loading with a twist which can be accompanied by a click.
The Sacroiliac Joint pain is characterised with difficulties with standing, walking, walking up the stairs, squatting getting out of the car, turning in bed which causes sleep disturbance. Psychosocial factors can influence the presentation and the symptoms. The Pain can refer to the pubic symphysis, the groin, the coccyx, and the posterior thigh.
Other associated symptoms: pelvic organ dysfunction, such as urinary incontinence, prolapse, or constipation and sexual dysfunction, It can also be associated with respiratory distress such as aberrant breathing patterns.
This table is adapted from a study by Zibis  on the characteristics and physical examination of Sacroiliac Joint Dysfunction:
Individual tests have low reliability in diagnosing Sacroiliac Joint Dysfunction. Instead, it's advised to use a cluster or a group of tests. The use of special tests is a useful clinical tool but not so reliable. A study by Dreyfuss et al found positive findings on Sacroiliac Joint provocative tests in asymptomatic patients.
The March/Stork test is a load transfer test of the ability of the pelvic girdle to transfer a load when lifting the opposite leg, A positive test however doesn't show where the failure of load transfer happened (on which level).
Active straight leg raise and Laslett's composite tests are validated but not specific and cannot be relied on in determining the cause of the pain.
The one-legged squat test, femoral glide test. passive accessory tests are unvalidated but you can help to compare the bilateral mobility of the joint
The Pelvic joint compression with the use of a sacroiliac belt can be very helpful to help control and increase force closure across that lumbar-pelvic area.
Imaging cannot be used to diagnose Sacroiliac Dysfunction but in the differential diagnosis of infections, metabolic disorders, fractures and tumours.
Sacroiliac Joint Infiltration can ease the symptoms when injecting an anaesthetic but it doesn't differentiate the pathological structure.
Ruling Out Deep Gluteal pathology
Symptoms are mainly located in the inferior gluteal aspect '' retro-trochanteric'' between the ischial tuberosity and the surrounding structures radiating onto the back of the greater trochanter.
Pain originating at the lesser trochanter which could possibly reflect ischio-femoral impingement,
The definition of greater trochanteric pain syndrome has now been expanded upon to include the insertional region of the Gemelli's and the Obturators.
Patients with Gluteal tendinopathy present with sleep disturbance and difficulties with physical activity and quality of life. Gluteal tendinopathy is highly present in menopausal or peri-menopausal females so it's important to rule out gynaecological pathologies.
Pain can refer to the groin, the coccyx, the anterior thigh, the lateral thigh around the sacroiliac joint, the buttock and down to the insertion of the iliotibial tract on the proximal tibia which makes it more difficult to differentiate it from Sacroiliac Joint.
This table is adapted from a study by Zibis  on the characteristics and physical examination of Gluteal Tendinopathy:
Ruling Out Piriformis Syndrome
Impingement of the sciatic nerve occurs mostly in the deep gluteal space and around the piriformis muscle than in the lumbar spine level.
This table is adapted from a study by Zibis  on the characteristics and physical examination of Piriformis Syndrome:
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