Adductor Strain

Updated: Jun 09, 2020
  • Author: Marlon P Rimando, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Overview

Practice Essentials

An adductor (groin) strain is a common problem among many individuals who are physically active, especially in competitive sports. The most common sports that put athletes at risk for adductor strains are football, soccer, hockey, basketball, tennis, figure skating, baseball, horseback riding, karate, and softball. [1, 2]  The initial management of an adductor injury should include protection, rest, ice, compression, and elevation (PRICE).

Hip adductor injuries occur most commonly when there is a forced push-off (side-to-side motion). High forces occur in the adductor tendons when the athlete must shift direction suddenly in the opposite direction. As a result, the adductor muscles contract to generate opposing forces.

One common cause of adductor strain in soccer players has been attributed to forceful abduction of the thigh during an intentional adduction. This type of motion occurs when the athlete attempts to kick the ball and meets resistance from the opposing player who is trying to kick the ball in the opposite direction. To a lesser extent, jumping also can cause injury to the adductor muscles, but more commonly, it involves the hip flexors. Overstretching of the adductor muscles is a less common etiology.

Symptoms of adductor strain

The patient typically complains of pain and stiffness in the groin region in the morning and at the beginning of athletic activity. Initial intense pain lasts less than a second. This initial pain is soon replaced with an intense, dull ache. Pain severity can vary with different patients. Pain and stiffness often resolve after a period of warming up but often recur after athletic activity.

Typical findings include tenderness at the origin of the adductor longus and/or the gracilis located at the inferior pubic ramus, as well as pain with resisted adduction.

Workup in adductor strain

Radiographs should be taken with the patient standing on one leg. Radiographs are used to evaluate for osteitis pubis with extrusion of the fibrocartilaginous disk and degeneration of adjacent bony margins.

Ultrasonograms may indicate abnormal findings, such as sonolucent areas and tendon fiber discontinuity that can be indicative of injury to the following 3 sites: (1) the tendon insertion, (2) the tendon itself, and (3) the musculotendinous junction. Ultrasonography can also be used to evaluate a mass.

Computed tomography (CT) scanning and magnetic resonance imaging (MRI) can be used to evaluate for complete and partial adductor muscle tears. [3]

Technetium-99m (99mTc) scanning has been shown to assist the physician in the diagnosis of osteitis pubis. [4]

Management of adductor strain

The initial management of an adductor injury should include protection, rest, ice, compression, and elevation (PRICE). Painful activities should be avoided. The use of crutches during the first few days may be indicated to relieve pain.

Grade I strain

Pain-free hip stretching exercises can begin immediately. Pain-free progressive strengthening exercises can also be initiated immediately and can progress to include hip flexion (with knee straight and bent) and adduction.

Grade II strain

Therapy should begin immediately with gentle, pain-free active range-of-motion (AROM) exercises of the hip. Isometric exercises should be initiated as soon as the patient can perform them without pain.

Grade III strain

Therapy includes PRICE plus a non–weight-bearing restriction for acute strains. Rest is required for 1-3 days, with continuous compression. If surgery is not indicated, pain-free isometric exercises and slow, pain-free AROM exercises can be started between days 3 and 5. The athlete should continue to use crutches until normal pain-free ambulation is possible.

Chronic strain

Rest, ice, massage, and therapeutic ultrasonography have been recommended to treat long-standing groin pain. Forceful adductor stretch under general anesthetic has also been recommended. A careful, monitored program with a total cessation of the sports activity is necessary for the chronic adductor injury to heal and become pain-free.

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Anatomy

The hip adductors are a powerful muscle group. They consist of the adductor magnus, minimus, brevis, and longus. The gracilis and pectineus muscles also are included. All of the adductor muscles are innervated by the obturator nerve (L2-L4) except the pectineus, which is innervated by the femoral nerve (L2-L4). The adductor magnus also is innervated by the tibial nerve (L4-S3). [5, 6, 7]

The origins and insertions of each of the hip adductors are noted below:

  • Adductor magnus/minimus: origin is the inferior pubic ramus/ischial tuberosity; insertion, linea aspera/adductor tubercle

  • Adductor brevis: origin is the inferior pubic ramus; insertion, linea aspera/pectineal line

  • Adductor longus: origin is the anterior pubic ramus; insertion, linea aspera

  • Gracilis: origin is the inferior symphysis/pubic arch; insertion, proximal medial tibia

  • Pectineus: origin is the pectineal line of pubis; insertion, pectineal line of femur

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Pathophysiology

The musculotendinous junction is thought to be the most common site of injury in a muscle strain. Studies in muscle physiology demonstrate that the sarcomeres near the junction are less elastic than those found at the central portion of the muscle. [8]

The adductor tendons have a small insertion area that attaches to the periosteum-free bone. This transitional zone is characterized by a poor blood supply and rich nerve supply, explaining the high level of perceived pain and poor healing characteristics of adductor strains.

The musculotendinous junction is likely to be vulnerable to indirect muscle injury that results from excessive force. Muscle strain injury has been characterized as occurring in response to forcible stretching of a muscle, most commonly while the muscle is activated. When the muscle is activated, muscle strain injury occurs, most often during eccentric (lengthening) contraction.

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Etiology

Injury to the hip adductors most commonly occurs following forced push-off (side-to-side motion). An extreme amount of stress is placed on the adductor tendons when, because of the athlete's momentum, a large amount of force is applied to one side in the sagittal plane and the adductor muscles must contract rapidly to shift the force to the opposite direction.

Rapid adduction of the hip against an abduction force (eg, changing direction suddenly in tennis), acute forced abduction that puts an unusual stretch on the tendon (eg, a rugby tackle), and a sudden acceleration in sprinting are the most common mechanisms of injury. Jumping is involved to a lesser extent than abduction and is associated more commonly with hip flexor strains. Overstretching of the adductor tendons is a much less common cause. [9, 10, 11]

Failure to stretch the adductor muscles properly puts them at increased risk for injury. Weakness of the adductor muscles is a common problem that puts these muscles at increased risk for injury, as the load to failure is much less in weaker muscles.

A systematic literature review by Ryan et al indicated that for participants in field-based sports, those who have sustained a groin/hip injury are at the greatest risk for future injuries of this type. The report, based on seven high-quality studies, identified 11 significant risk factors for groin/hip injuries in field-based sports. In addition to previous injury, the next most prominent risk factors were older age and weak adductor muscles. [12]

Similarly, a prospective cohort study by Mosler et al indicated that in male professional soccer players, the risk of groin injuries is increased in relation to previous groin injuries and abnormally high or low eccentric adduction strength. The investigators found that the hazard ratio (HR) for hip/groin injury is raised to 1.8 when previous hip/groin injuries have occurred and to 1.6 in association with higher than normal eccentric adductor strength. Additionally, lower than normal eccentric adductor strength is linked to an HR of 1.7 specifically for adductor-related injuries. However, the study also found that these factors are not strongly enough associated with likelihood of injury to identify whether a specific individual is at risk of injury. [13]

A study of 110 male athletes with sports-related acute groin pain (66% of whom had adductor injuries) found that change of direction was the most common cause of the injury in most sports (31%), although in soccer, kicking was the most frequent mechanism (40%). Of adductor injuries, imaging showed the adductor longus to be involved in more than 90% of cases. [14]

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Epidemiology

Muscle strain is the most frequent injury observed in sports. Up to 30% of office visits in a primary care sports medicine practice are attributed to muscle strain. As with other musculotendinous injuries, increased age is related to elevated risk for strains due to reduced elasticity of connective tissue.

Scandinavian soccer studies have reported groin injury rates of 10-18 injuries per 100 soccer players each year. Lovell studied 189 cases of chronic groin pain in which he attributed 30% to adductor injuries. [15] The Renstrom and Peterson study found the adductor longus was responsible for 62% of groin injuries. [16] Injuries to the groin account for 5% of all soccer injuries and 2.5% of karate injuries.

An epidemiologic study by Eckard et al reported that among student athletes in the National Collegiate Athletic Association (NCAA), for the 2009/2010-2014/2015 academic years, 1.29 hip adductor strains occurred per 10,000 athlete-exposures (AEs), including 1.71 per 10,000 AEs in men and 1.15 per 10,000 AEs in women. [17]

Sex

According to a literature review by Orchard, moderate evidence suggests that among men and women playing the same sport, the risk of groin injury is greater in males. [18]

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Prognosis

Improper management of acute adductor strains or returning to play before pain-free sport-specific activities can be performed may lead to chronic injury. According Renstrom and Peterson, 42% of athletes with groin muscle-tendon injuries could not return to physical activity after more than 20 weeks following the initial injury. [16] This prolonged length of time seems to indicate the importance of proper management of these injuries in the acute stage.

In a study of 81 adult male athletes, Serner et al reported that following acute adductor injury, a longer period before return to sport is most strongly predicted by palpation pain at the proximal adductor longus insertion, a palpable defect, and/or, as found on MRI, a bone-tendon junction injury. [19]

Another study by Serner et al found that in adult male athletes with acute adductor injury who were treated with a supervised, standardized, criteria-based exercise rehabilitation program, the period of time for return to sport did not statistically differ between those with an MRI-based grade 0, I, or II injury. It took a median 13 days for the athletes with grade 0-II injuries to achieve a clinically pain-free state, while controlled sports training for these individuals was completed in a median 17 days, and a return to full team training took place in a median 18 days. Athletes with a grade III injury (complete tear/avulsion) reached these milestones in a median 55, 68, and 78 days, respectively. [20]

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Patient Education

The patient needs to be educated on proper treatment following an acute groin injury. PRICE (protection, rest, ice, compression, and elevation) needs to be emphasized to ensure that swelling is reduced. In the acute stage, inform patients to avoid activities that may be harmful and to promote increased blood flow to the adductor muscles by use of hot packs, hot showers, or massage. The athletic trainer and/or physical therapist should instruct the patient in proper exercises to rehabilitate the adductor muscles and enable the patient to return safely to participation in a sport or activity.

As is the case in many injuries involving athletes, outside influence on the physician to return the athlete to play before being medically ready can be a problem. The best interest of the player must take precedence in this situation. Returning players with an adductor injury to their sport too quickly can have a detrimental effect on a future career. Adductor injuries have a tendency to become chronic when not properly treated.

For excellent patient education resources, visit the Sports Injury Center, as well as Muscle Strain.

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