Iliocostal friction syndrome

Iliocostal friction syndrome can be a disabling painful condition that can affect the quality of life for individuals.[1] The predominant symptom is low back pain, which may radiate to the lower rib cage, flank, groin, buttock, and thigh.[2] Individuals may also experience intermittent aches along with a 'grating sensation' in the hip.[3] The pain may be aggravated by moving, twisting, bending, or by changing positions.[4] The condition may be bilateral as seen in individuals with hyperkyphosis or osteoporosis, but is more commonly unilateral as seen in individuals with scoliosis.[5]

Iliocostal friction syndrome is a result of the lower ribs coming in contact with the iliac crest due to a reduced costoiliac distance.[6] There are several conditions in which may cause iliocostal friction syndrome to occur both unilaterally or bilaterally.

X-ray of individual with scoliosis

Bilateral causes

Iliocostal friction syndrome most commonly occurs bilaterally as a result of spinal osteoporosis.[2] Osteoporosis is a condition in which the bone density and quality deteriorates, resulting in an increased risk for fractures. More than 2 million fractures occur anally in the United States due to osteoporosis.[9] The most common fractures that occur due to osteoporosis is in the hip or vertebrae,[10] resulting in a loss of space between the ribs and the iliac crest. It is estimated that osteoporosis can cause 25% of females over 50 years of age within the United States to have at least one vertebral fracture in their lifetime.[11] Factors that make an individual more at risk for experiencing a fracture includes age, sex, weight, height, family history, rheumatoid arthritis, previous fracture, secondary osteoporosis, alcohol or smoking use, glucocorticoid use, and the femoral neck bone mineral density of the individual.[10]

Effects of osteoporosis on the spine

Another cause for bilateral iliocostal contact is based on the kyphosis curve of the spine. The thoracic spine is slightly curved due to the shape of the vertebral bodies and intervertebral discs, with a normal Cobb angle measurement between 20 to 40 degrees. Hyperkyphosis is a condition in which the curve of the kyphosis angle measures over 50 degrees. The kyphosis angle can be influenced by age, muscle tone,[12] vertebral fractures, and intervertebral degenerative disc disease.[13] Hyperkyphosis can result from posture, a congenital deformity, heritable conditions such as Scheuermann's disease,[14] tumours, trauma, neuro-muscular disease, postlaminectomy syndrome, dwarfism, and infections such as tuberculosis which can result in Pott's disease.[15] The curvature of hyperkyphosis may result in a decrease of space between the ribs and the iliac crest, causing iliocostal friction syndrome.[11]

Under normal conditions, there is no iliocostal contact due to enough distance between the lower ribs and the iliac crest. Individuals with iliocostal friction syndrome may have their 10th, 11th, or 12th rib come in contact with the iliac crest.[4] Structures of the body can be irritated as a result of iliocostal contact includes the nerves,[8] tendons, and muscles surrounding the area.[16]

There are several nervous branches surrounding the iliac crest that may be impinged or irritated upon contact. The superior cluneal nerves travel through the thoracolumbar fascia and drape over the iliac crest.[5] The posterior branches of the iliohypogastric nerve can emerge on the surface above the iliac crest, with the nerve draping lower than usual in some individuals.[8] Similarly, the ilioinguinal nerve runs below the iliohypogastric nerve, following just above the iliac crest.[17] These nerves may be impinged or irritated as a result of the lower ribs coming in contact with the iliac crest.[5]

Muscles of the abdomen

The top of the iliac crest includes the attachments of the latissimus dorsi, the transversus abdominis, as well as the internal and external obliques. The quadratus lumborum also connects from the back tip of the iliac crest up to the 12th rib.[18] These tendon and muscle structures surrounding the iliac crest are at risk for irritation due to iliocostal contact. Tendon irritation can result in referred pain, therefore affected individuals may experience pain throughout the hip, low back, the groin, chest, and thigh. This contributes towards the difficulty in diagnosis of iliocostal friction syndrome.[4]

The diagnosis of iliocostal friction syndrome can be made clinically without any imaging.[4] Typically, individuals with the syndrome will have an underlying condition such as scoliosis or osteoporosis in which may cause the iliocostal contact.[8] The examiner will assess for the possibility of contact by noting the medical history and reported symptomology by the individual. The clinician will examine the individual for iliocostal contact within a standing position and in movement.[4] Tenderness of the iliac crest and the lower ribs will be assessed with physical palpation.[16] Usually, flexion of the trunk laterally can trigger pain on the affected side(s), which is useful in diagnosis to pinpoint the exact location of iliocostal contact.[8]

Though radiological imaging is not needed for iliocostal friction syndrome diagnosis, it is often uses to assess for underlying conditions and rule out differential diagnosis. Imaging such as the use of an x-ray can reveal irregularities of the surfaces of the lower ribs and iliac crest or abnormally long 12th ribs, which may give suspicion to the diagnosis of iliocostal friction syndrome.[3][6] Computed tomography (CT) scans can reveal kyphotic deformities, including a reduced distance between the lower ribs and the iliac crest, giving rise to the possibility of iliocostal contact.[19]

Muscles of the back, with iliac crest depicted in red

A brace used to treat hyperkyphosis

The most common method for treating iliocostal friction syndrome is usually with acupuncture,[16] physical therapy, muscle relaxants, and activity modification.[19] Treatment may involve addressing the underlying pathology of the condition as hyperkyphosis, osteoporosis and scoliosis may be treated with postural training and muscle strengthening methods. Orthosis, a specialty that involves individuals being fitted with a brace or harness may help correct the curvature of the spine.[6][20] Rib-compression belts have also been used as a conservative form of treatment for iliocostal friction syndrome. A 3-inch wide lower rib-compression belt is fitted above the iliac crests and tightly adjusted to provide pressure on the lower ribs. Since the lower ribs are attached to the sternum by flexible hyaline cartilage, they can be pushed inward with ease, and as a result, the compression shifts the ribs away from the iliac crests, preventing iliocostal contact.[2][4]

Local injections or nerve blocks containing steroids or lidocaine may also be used if other conservative methods of treatment have failed to provide adequate relief.[8] The injections are inserted into the junctions near the iliac crest as well as the lower rib margins,[2] and often have to be repeated as they only give relief for a short duration of time.[3] Prolotherapy has also been used to treat iliocostal friction syndrome, as the tendinous and muscle structures surrounding the iliac crest may be damaged as a result of iliocostal friction. Hypertonic dextrose is a common medication used in prolotherapy, sometimes diluted with lidocaine, which is injected along the iliac crest. Treatment is usually weekly or bi-weekly, and up to 6 sessions may be necessary to relieve tenderness in the area.[4] The most invasive method for treating iliocostal friction syndrome is the surgical resection of the floating ribs,[2] which excises the outer two-thirds of the rib while the individual is under anesthesia.[3] Special attention is made to preserve the intercostal nerve not to cause intercostal neuralgia.[8]