An adductor strain, or pulled groin, is a common injury seen among athletes today. A muscle strain occurs when it is forcibly stretched while concentrically contracted.

Causes / typical injury mechanism: Adductor strains often are the result of an acute injury that occurs during sudden changes in direction or during the push off phase of sprinting. During the rapid acceleration or deceleration while performing these maneuvers, the adductor complex overstretches, resulting in injury of the muscle, most often in the myotendinous junction.

Classic history and presentation: Adductor strains classically present in an athlete complaining of sudden and severe medial thigh or groin pain that worsens with activity. Patients often describe a particular moment when they felt a pull or over-stretch in their groin during play, as opposed to a more insidious onset.

Prevalence: An adductor strain has the highest prevalence among hockey and soccer players, although it is a common injury in other sports including football, tennis, basketball, and figure skating. Muscle strains remain the most common injury among athletes with adductor strains making up approximately 20% of all muscle strains, second to only the hamstrings.

• Age – Can occur in all ages, although it is most prevalent in the 2nd through 4th decades of life.
• Sex / gender – Slightly higher predominance in men compared to women.

Risk factors: Risk factors include previous hip or groin injury. Weak adductors, muscle fatigue, decreased range of motion, and inadequate stretching or warming up of the adductor muscle complex prior to sport have all been noted to increase risk. Also, increasing age has been shown to predispose patients to these injuries when participating in physical activity.

Pathophysiology: The classic mechanism of a muscle strain occurs when a muscle is being forcibly stretched while concentrically contracted. The greatest eccentric tension is placed on the adductor complex when the leg is in an externally rotated and abducted position. Sudden change in direction causes rapid adduction of the hip against an abduction force, putting increased stress on the adductor tendons. As a result, the adductor muscles contract to generate both eccentric and concentric opposing forces. The strong eccentric contraction of the adductors commonly leads to injury of 1 of 6 adductor muscles (longus, magnus, brevis, gracilis, obturator externus, and pectineus), with the most commonly injured being the adductor longus; likely the result of the low tendon to muscle ratio at its origin.

Grade / classification system:

• 1st degree – Pain with minimal loss of strength and motion (ie, strain)
• 2nd degree – Pain with compromised strength (ie, partial tear)
• 3rd degree – Pain with complete disruption of muscles or tendon fibers and loss of muscle function (ie, complete tear)