Adductor Strain and Groin Injuries: Assessment, Grading, and Return to Sport

The Adductor Complex

The adductor group comprises five muscles on the medial aspect of the thigh: adductor longus, adductor brevis, adductor magnus, gracilis, and pectineus. All originate from the pubic bone and inferior pubic ramus, and all share the primary function of hip adduction (drawing the thigh toward the midline). Adductor longus is the most commonly injured — its proximal musculotendinous junction, where the tendon transitions to muscle just below its origin at the pubic body, is the most mechanically vulnerable zone. The adductors are also involved in hip flexion (particularly adductor longus), stabilisation of the pelvis during single-leg stance, and proprioceptive contributions to lumbopelvic control.

Mechanism of Injury

Adductor strains typically occur during high-speed change of direction, explosive kicking, or forced hip abduction against a resisting adductor contraction — the muscle-tendon unit is unable to tolerate the eccentric load placed on it. In football (soccer, AFL, rugby), acceleration, deceleration, cutting, and kicking mechanics repeatedly place the adductors under high eccentric demands. A sudden slip into hip abduction — on a wet surface or from a tackle — is a classic acute mechanism. Chronic or insidious adductor pathology (adductor-related groin pain) typically develops from repetitive training load that outpaces tissue recovery, often in pre-season contexts with rapid increases in running and sprint volume. Prior groin injury, hip adductor weakness, and reduced hip adductor to abductor strength ratio are established risk factors.

Grading Muscle Strains

Muscle strains are graded on a three-tier system. Grade I: minor tearing of a small proportion of muscle fibres, with localised pain but preserved strength and minimal functional limitation. Grade II: partial tear involving a significant proportion of fibres, with moderate pain, weakness, and a discernible loss of function — localised bruising may appear within 24–48 hours. Grade III: complete rupture of the muscle or tendon, producing severe pain, a palpable defect, extensive bruising, and complete strength loss. Grade III adductor longus tears from the pubic origin are relatively rare but do occur in explosive sport contexts and occasionally require surgical repair. The vast majority of adductor strains are grade I or II and are managed conservatively.

Rehabilitation and Return to Sport

Acute management follows a modified PEACE and LOVE framework: protection from re-injury, graduated elevation, avoidance of harmful anti-inflammatory interventions in the remodelling phase, compression, and patient education followed by progressive loading, optimism, vascularisation through gentle movement, and early exercise. The Copenhagen adductor exercise — a side-lying adductor-loading exercise progressed in range and resistance — has the strongest evidence base for both rehabilitation of existing adductor injuries and prevention of future recurrence. Hip adductor strengthening progresses from isometric adductor squeezes, through isotonic ball squeeze exercises and side-lying hip adduction, to functional loading: lateral band walks, cossack squats, slide-board exercises, and sport-specific cutting and kicking mechanics.

Return to sport is determined by symmetrical hip adductor strength on hand-held dynamometry or isokinetic testing, pain-free completion of sport-specific movement demands, and adequate eccentric load tolerance — not solely by time elapsed since injury. Premature return before these criteria are met is the primary driver of re-injury.