How To Treat Sesamoid Injuries In Athletes
It has been speculated that 50 to 75 percent of weightbearing forces are transmitted through the first metatarsophalangeal joint (MTPJ) complex during weightbearing and these forces can account for up to three times one’s body weight.1,2 Anatomical location of the hallucal sesamoids predisposes them to significant shear, pressure and ground reactive forces during weightbearing activities. As a result, sesamoids are a site for potential injury. Sesamoid pathology is not uncommon in a typical podiatric sports medicine practice. In a study of 1,000 running injuries, the sesamoids were involved 12 times (1.2 percent incidence).3 Sesamoid injuries accounted for 12 percent (12/100) of great toe complex injuries and four percent of all foot and ankle injuries (12/300).3 Theoretically, the hallucal sesamoids protect the flexor hallucis longus during the push-off phase of gait, absorb shock, increase FHB lever action across the first MTPJ and elevate the first metatarsal to evenly distribute weightbearing forces to the lesser metatarsal heads. In two in vitro laboratory studies on hallucal sesamoid function, Aper, et. al., concluded the prime functions of the sesamoids are maintaining a constant FHL tendon leverage across the first MTPJ and allowing the FHB muscle to stabilize the hallux during stance for controlled and levered propulsion.4,5 Reviewing Potential Etiologies Direct and indirect macrotrauma as well as recurrent microtrauma can contribute to sesamoid pathology. Direct trauma includes contusions and crushing injuries. Indirect traumatic injury occurs with forced dorsiflexion. One may see this with or without hallux abduction with resulting sesamoid compression against the metatarsal head (i.e., “turf” toe). During toe off at maximal hallux dorsiflexion, the sesamoids are in their most distal position, moving up 1 cm from their proximal resting position. Being fixed in this distal position subjects the sesamoids to significant ground reactive and tendon forces. Given this position at toe-off, recurrent microtrauma has been implicated in sesamoid pathology and this likely represents most of the sesamoid injuries one would see in a sports medicine practice. Any sport or activity involving sudden starting and stopping with repetitive first MTPJ extension can predispose patients to sesamoid injuries. There are also certain foot types and conditions, such as excessively pronated or severe cavus feet, a plantarflexed and/or long first ray, ankle equinus deformities and bunion deformities with deviated sesamoids that can increase the risk for sesamoid disorders. What To Look For In The History And Physical Exam A complete history, thorough physical exam and timely diagnostic testing are required to differentiate sesamoid pathology from other great toe joint pathology. For the patient history, one should ascertain the duration of the problem, the mechanism of injury, aggravating factors (i.e., pain with propulsion), and any type or change in activity. One should also assess footwear, consider any sport-specific demands and obtain a summary of previous self- or professional treatment. A general, lower extremity physical examination and focal physical examination of the sesamoid apparatus should then be performed. This should include inspection, range of motion, muscle testing, direct palpation and provocative maneuvers. You must also evaluate the patient’s gait and inspect the patient’s footwear. For the gait evaluation, one should look for any asymmetry, antalgia or compensation. During the physical exam, these patients will commonly experience pain upon direct palpation of the involved sesamoid, pain with maximum hallux dorsiflexion, and have pain or a loss of strength when testing for hallux flexion. Hallux dorsiflexion is the most reproducible provocative maneuver as it involves stabilizing the sesamoid in its most distal position and then plantarflexing the hallux while maintaining pressure on the sesamoid.6 You may note edema, warmth, erythema, ecchymosis and crepitus but they are not specific for sesamoid dysfunction. Pertinent Insights On Diagnostic Testing At this point, the clinician should develop a broad differential diagnosis including potential sesamoid and non-sesamoid pathology (see “Differential Diagnosis Of Sesamoid Pathology” below).