Definition

Hip adductor strain refers to an injury of the hip adductor muscles at the muscle belly, myotendinous junction, or tendon. It can be an acute or chronic injury. The hip adductor muscles include the adductor magnus, adductor brevis, adductor longus, pectineus, and gracilis muscles (Fig. 53.1). All of these muscles are innervated by the obturator nerve with the exception of the pectineus muscle, which is innervated by the femoral nerve. Their functions include hip adduction and hip flexion. Adductor strain is the most common cause of acute groin pain in athletes [1]. The adductor longus myotendinous junction is the most commonly injured site [2].

A prospective cohort study of the incidence of groin injuries during a 1-year period among Swedish male club soccer players reported that 8% of all injuries were in the groin area, and 52% of these were attributed to adductor muscle or tendon injuries [3]. A similar incidence was reported in a study of Norwegian female elite soccer players, in which 9% of all injuries were hip or groin strains; 83% of these were acute injuries and 17% were secondary to overuse [4]. For male ice hockey players of a single National Hockey League team, Tyler and colleagues [5] reported 3.2 strains per 1000 player-game exposures. Orchard and Seward [6] monitored all the injuries that occurred in the Australian Football League during 4 consecutive years. In total, more than 660 elite male athletes played 22 matches per season among 16 teams. There was an incidence of 3.3 groin strains per team per season, the second most common musculoskeletal injury after hamstring strain, and a recurrence rate of 21%. In addition, it was the third most prevalent injury after hamstring strain and anterior cruciate ligament tear, with 11.9 matches missed per team per season. A retrospective cohort study of 500 Australian Football League players indicated that 17% sustained a hip or groin injury during their junior years. Of these, 31% were secondary to a hip adductor strain or tear, and 17% were recurrent injuries [7]. Recurrence of hip adductor strains has been reported to be as high as 32% to 44% in ice hockey and Australian football athletes [5,8]. Adductor strains in elderly athletes older than 70 years occur at a slightly decreased incidence of 5% [9]. The incidence and prevalence of hip adductor strains in sedentary patients are unknown.

Athletes who participate in sports that require cutting and sudden change of direction (e.g., soccer, ice hockey, Australian-rules football) are at increased risk for this injury [10]. Adductor strains may also occur from an eccentric contraction of the adductor muscles opposing the abductor muscles, as may be seen with an explosive lateral propulsion in ice hockey [11]. Hip adductor strains have been attributed to low strength or flexibility of this muscle group [12]. There is usually poor conditioning of the trunk and lower extremities characterized by muscle imbalance among the pelvic stabilizing muscles, including the hip abductor and adductor muscles, as well as the core muscles and hip flexors [10]. In addition, poor technique and overuse are risk factors for adductor strains. In rare instances, sacroiliac dysfunction may be associated with adductor injuries [13].

Adductor strains may be classified according to functional limitation on physical examination or pathologic injury on radiographic imaging (Table 53.1). The functional classification may or may not directly correlate with the pathologic change of the tissue seen on radiographic imaging. If the injury is localized at the tendon or myotendinous junction, it may also be described as an adductor tendinitis, referring to an acute injury with active inflammatory process, or as an adductor tendinosis, referring to a chronic injury that is causing functional limitations and does not have an ongoing inflammatory reaction. Because it may be difficult to classify the presence of an inflammatory process, tendinopathy is used frequently to refer to an adductor tendon or myotendinous injury with partial or complete loss of function that may be acute or chronic.

Symptoms

Patients with hip adductor strains complain of sharp, stinging, or aching pain in the groin area that may radiate down to the anteromedial thigh. Symptoms are worse when they adduct and flex the leg at the hip, such as when they move the outside leg into a car. They usually report tightness in the groin or anteromedial pelvic girdle region. In injuries involving a partial or complete tear of the muscle or tendon, they complain of soft tissue swelling and bruising in the medial thigh. Chronic injuries may hurt only during physical activity or sports participation.

Physical Examination

The patient presents with tenderness to palpation in the groin region, most commonly over the adductor longus tendon or myotendinous junction distal to the origin of the muscle at the anterior surface of the pubis between the crest and the symphysis. In severe injuries, a defect may be palpated in the muscle representing a tear in the muscle or tendon. There can be associated ecchymosis, swelling, and tenderness of the surrounding soft tissue. Antalgic gait may be noted with ambulation secondary to pain or dysfunction. Single-leg standing and squatting may reveal Trendelenburg sign, excessive hip internal or external rotation, or genu valgus or varus.

Pain or weakness of the hip adductor muscle may be elicited with active resisted hip adduction, hip adduction and flexion, and hip flexion. Groin pain may also be reproduced with passive forced hip abduction as well as with passive flexion, abduction, and external rotation of the hip (FABER test). The cross-over sign may be used to determine if the adductor strain is moderate to severe and likely to cause functional impairment. This maneuver consists of reproducing the typical groin pain while performing any of the provocative maneuvers mentioned before on the contralateral side (i.e., FABER test, active resisted hip adduction, or passive hip abduction). The squeeze test and the static resisted hip adduction test are specific examinations for hip adductor muscles. During the squeeze test, the patient is in the supine position with feet on the table, hips flexed to 45 degrees, and knees flexed to 90 degrees. The examiner places the fist between the knees and asks the patient to squeeze the fist by adducting the hips bilaterally. The resisted hip adduction test consists of laying the patient supine with legs straight, positioning each leg at 15 degrees of abduction, and bilaterally resisting active hip adduction.

Functional Limitations

Patients usually have difficulty with walking, running, doing pivot turns, going up and down stairs, and standing up from a sitting position and vice versa. As mentioned before, getting in and out of a car is particularly painful. Sexual intimacy is frequently avoided because of the proximity of the injury to the sexual organs and groin pain experienced as the adductor muscles contract to stabilize the pelvis.

Hip adductor strains present with significant functional limitations during sports participation and interfere with athletes’ optimal performance. They may report difficulty with propulsion in the lateral direction due to the eccentric contraction of the hip adductor muscles attempting to decelerate the leg stride, tightness in the groin region despite stretching, and loss of maximal sprinting speed, among other complaints [10,14]. The biomechanics of movements involving the hip joint are consequently altered as the athlete tries to avoid experiencing pain. If it is left uncorrected, this adaptation eventually leads to other injuries, such as contralateral hip adductor strain, osteitis pubis, and sports hernia.

Diagnostic Studies