Slipping rib syndrome

Anatomy of the rib cage

The presentation of slipping rib syndrome varies for each individual and can present at one or both sides of the rib cage, with symptoms appearing primarily in the abdomen and back.[3] Pain is most commonly presented as episodic and varies from a minor nuisance to severely impacting quality of life.[1][4] It has been reported for symptoms to last minutes to hours.[3][5]

One of the commonly reported symptoms of this condition is the sensation of "popping" or "clicking" of the lower ribs as a result of subluxation of the cartilaginous joints.[1][3] Individuals with SRS report an intense, sharp pain that can radiate from the chest to the back, and may be reproducible by pressing on the affected rib(s).[4][6] A dull, aching sensation has also been reported by some affected individuals.[3] Certain postures or movements may exacerbate the symptoms, such as stretching, reaching, coughing, sneezing, lifting, bending, sitting, sports activities, and respiration.[1][3][4] There have also been reports of vomiting and nausea associated with the condition.[7]

The causes of slipping rib syndrome are unclear,[8] although several risk factors have been suggested. The condition often accompanies a history of physical trauma. This observation could explain reports of the condition among athletes, as they are at increased risk for trauma, especially for certain full-contact sports such as hockey, wrestling, and American football.[7] There have also been reports of slipping rib syndrome among other athletes, such as swimmers, which could plausibly result from repetitive upper body movements coupled with high physical demands.[3][9]

Reported incidents in which no history of traumatic impact to the chest wall has been described are considered a gradual onset.[8] Slipping rib syndrome may also result from the presence of a birth defect, such as an unstable bifid rib.[9] Generalized hypermobility has also been suggested to be a possible further risk factor.[3]

The "hooking maneuver" being performed on a model skeleton.

Diagnosing slipping rib syndrome is predominantly clinical,[10][11] with a physical examination of the affected rib being the most commonly utilized. A technique known as the "hooking maneuver" is commonly used amongst medical professionals to diagnose slipping rib syndrome. The examiner will hook their fingers under the costal margin, then pull in an anterior (outward) and superior (upward) direction, with a positive result when movement or pain is replicated during this action.[7]

Plain radiographs, CT scans, MRI, and standard ultrasound, are all unable to visualize the cartilage affected by SRS; however, they are often used to exclude other conditions.[3] Dynamic ultrasound is occasionally used to evaluate the dynamic laxity or displacement of the cartilage;[10] however, it has been said to be not much superior to that of a physical examination from an experienced physician, as a diagnosis is dependent on the technician's expertise and knowledge of the condition.[9] A positive result of a dynamic ultrasound for slipping rib syndrome requires an observed subluxation of the cartilage, which may be elicited with the Valsalva, crunch, or other maneuvers.[12][13] Nerve blocking injections have also been utilized as a diagnostic method by noting the absence of pain following an injection to the intercostal nerves of the affected ribs.[14][11]

Treatment modalities for slipping rib syndrome range from conservative measures to surgical procedures.

Slipping rib syndrome is considered to be underdiagnosed and frequently overlooked.[1][19] Past literature has noted the condition to be rare or uncommon, but one 1980 study estimated SRS to have 1% of clinical diagnoses in new patients at a general medicine clinic and 5% at a specialty gastroenterology clinic, with the prevalence being even higher for patients referred to the specialty clinic after multiple negative investigations.[1][20] A separate study from 1993 found that slipping rib syndrome accounted for 3% of new referrals to a mixed specialty general medicine and gastroenterology clinic.[2]

It is unclear whether SRS is more common in women as some studies report an equal gender distribution while others report the condition to occur more often in females.[1][2][20] It has been suggested by some researchers that there is a hormonal connection between hormones and the increased ligament laxity observed in females during pregnancy, though this theory has yet to be upheld or explored.[11]

Slipping rib syndrome was first mentioned in 1919 by Edgar Ferdinand Cyriax, an orthopedic physician and physiotherapist, who described a chest pain associated with a "popping" or "clicking" sensation.[9][21] The condition was originally named after him, Cyriax syndrome, but has used multiple names since then, including clicking rib syndrome, painful rib syndrome, interchondral subluxation, and displaced ribs.[22] The name "slipping rib syndrome" was first used by surgeon Robert Davies-Colley and gained popularity, becoming the most commonly quoted term for the condition.[8] Davies-Colley was also the first to describe an operation for slipping rib syndrome, a costal cartilage removal.[3][23]

The "hooking maneuver" was noted in 1977 by Heinz & Zavala to be useful for slipping rib syndrome as an accurate diagnostic method.[4][24]