Adductor Strain

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

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.

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]

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]

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]

An additional study by Serner and colleagues found that in male athletes with acute adductor injuries, progress gained through rehabilitation was only roughly revealed through repeated measures of adductor strength, flexibility, and palpation pain. The investigators reported that measurements involving the extent of palpation pain, the bent-knee fall-out test, hip abduction range of motion, and eccentric hip adduction strength could not “define a precise recovery point during rehabilitation.”[21]

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.

Generally, symptoms are more diffuse, with typical complaints 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. Groin pain can represent a number of different diagnoses, and all differential diagnoses should be kept in mind when assessing the patient. Obtain information about the mechanism of injury and loss of function, as well as about the location, quality, duration, and severity of pain. The aggravating and alleviating factors also should be noted.

Usually, pain is described at the site of the adductor longus tendon proximally, especially with rapid adduction of the thigh. As the injury becomes more chronic, pain may radiate distally along the medial aspect of the thigh and/or proximally toward the rectus abdominis. Acute injuries are described as a sudden ripping or stabbing pain in the groin, and chronic injuries are described as a diffuse dull ache.

Exercise-induced medial thigh pain over the area of the adductors, especially after kicking and twisting, may indicate obturator neuropathy. Pain at the symphysis pubis or scrotum may be more consistent with osteitis pubis. Conjoined tendon lesions present as pain that radiates upward into the rectus abdominis or laterally along the inguinal ligament; exquisite tenderness is present at the site of the injury.

True loss of function is not observed unless a grade III tear is present. In the case of a severe tear, loss of hip adduction occurs. Loss of function also should alert the physician to possible nerve involvement (obturator nerve entrapment).

The acute adductor strain commonly occurs at the musculotendinous junction. Tenderness, swelling, and ecchymosis can be observed at the superior medial thigh. Sometimes, a defect in the muscle can be palpated. Pain is noted with resisted adduction and full passive abduction of the hip.

A pure hip adductor strain can be distinguished from combination injuries involving the hip flexors (ie, iliopsoas, rectus femoris) by having the patient lie in the supine position. If more discomfort is reproduced with resistive adduction when the knee and hip are extended than if the hip and knee are flexed, a pure hip adductor strain can be assumed.

Physical findings can help distinguish adductor strains from other causes of groin pain, such as the following:

• Iliopsoas strain: hip flexion against resistance is painful; tenderness is difficult to localize because the insertion of the iliopsoas is deep

• Osteitis pubis: tenderness of the symphysis pubis and possible loss of full rotation of one or both hip joints are noted

• Conjoined tendon lesions (ie, sportsman's hernia): exquisite tenderness upon palpation at the inguinal canal; having the patient cough reproduces pain

• Obturator neuropathy: adductor muscle weakness, muscle spasm, and paresthesia over the medial aspect of the distal thigh may be present; loss of adductor tendon reflex with preservation of other muscle stretch reflexes often is observed; a positive Howship-Romberg sign (medial knee pain induced by forced hip abduction, extension, and internal rotation) sometimes is observed

If a mass is felt in the middle to upper thigh, the physician must consider a rupture at the distal musculotendinous junction. Tumor and hernia also should be ruled out. These conditions warrant a surgical consultation.

Obturator nerve entrapment should be suspected if there is exercise-induced medial thigh pain that starts at the origin of the adductor longus and radiates distally along the medial thigh. Denervation of the adductor muscles is seen on needle electromyography (EMG). The treatment for obturator nerve entrapment is nonoperative, with surgical neurolysis in recalcitrant cases.

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. CT scanning and 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]

Urinalysis should be considered only if a genitourinary cause is suggested.

A study by Falvey et al indicated that the adductor squeeze test has 85.4% sensitivity for athletic groin pain from pubic aponeurosis injury or adductor pathology but is not specific for these. The study involved 382 male patients.[22]

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. Use of steroid injections is controversial in adductor strains, because the potential exists for tendon rupture if the steroid is injected into the tendon itself. Obtain consultations as appropriate to rule out differential diagnoses.[23, 24, 25, 26, 27, 28]

Do not advance the athlete too quickly back to his/her sport, as the injury may become a chronic condition. Acute strains easily can become chronic strains if proper time is not allowed for healing. Chronic strains are much more difficult to manage.

Some authorities believe that stretching in the acute phase may aggravate the condition and lead to a chronic lesion. Control of muscle spasms is important for rehabilitation. Spasms may be alleviated with medication and/or modalities (eg, ice, electrical muscle stimulation). Passive range-of-motion (PROM) exercises are initiated when the patient can perform them without pain. Active muscle exercises can be advanced slowly from isometric contractions without resistance, to isometrics with resistance, progressing eventually to dynamic exercises when tolerated with little or no pain.[29, 30]

Strengthening abdominal and hip flexor muscles is an essential part of rehabilitation of groin injuries. Coactivation of the abdominal muscles and the adductor muscles is a useful and functional exercise. Completing many repetitions increases the endurance of the adductor muscles. A fatigued muscle/tendon complex is more vulnerable to injury. The patient should aim to progress gradually to 30-40 repetitions. Proprioceptive exercises are recommended, along with stretching, as well as an aquatic training program if accessible. After several days, heat and support bandages are recommended.

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.

Therapy may be advanced to include the slide board, plyometrics (lateral sliding, lateral lunges, and X lunges), and, finally, sport-specific functional drills. (See the images below of lateral and X lunges.) The athlete may not be required to miss competition time, depending on the severity of the injury.

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.

After 1 week, pain-free slide board exercises and plyometrics can be initiated. Soon after the first week, sport-specific functional drills can begin. An athlete with a grade II strain may miss 3-14 days of competition, depending on the severity of the injury.

Grade III strain (nonsurgical)

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.

Initiate pain-free stretching exercises, progressive-resistance strengthening exercises (without pain), and proprioceptive neuromuscular facilitation (PNF) between days 7 and 10.

Usually within 10 days after starting progressive-resistance strengthening exercises, the patient should be able to perform pain-free slide board exercises and plyometrics and eventually advance to sport-specific functional activities.

Chronic strain

Rest, ice, massage, and therapeutic ultrasonography have been recommended to treat long-standing groin pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) and steroid injections have been suggested but have not been supported by controlled trials. Forceful adductor stretch under general anesthetic has 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.

The physical therapy program should consist of isometric exercises, strengthening of the hip- and pelvis-stabilizing muscles, and proprioceptive training. No increase in pain should be experienced during or after the exercises. The load of the exercises is gradually increased. Specific strengthening of the adductor muscles is then implemented.

Cycling can be used to maintain general conditioning, but running can begin only after the patient can perform the exercises at high intensity without pain. Sprinting and cutting activities may then follow. Sport-specific training is the final step before full return to sport. This part of the rehabilitation program may take 3-6 months.

Use of steroid injections is controversial in adductor strains, because the potential exists for tendon rupture if the steroid is injected into the tendon itself. Renstrom advocates injection of local anesthetic with or without corticosteroids into the tendon periosteal area if conservative treatment has been unsuccessful for 2-4 months. This treatment should be combined with 1-2 weeks of rest from activity after injection.[16, 31, 32]

Surgery is indicated in acute strains only when there is rupture and in select chronic strains that are refractory to conservative treatment. In the surgical procedure, the patient is in the supine position with the knee in 90° of flexion and the hip in 45° of flexion. The adductor longus tendon is identified, and a skin incision is made. A discoloration of the tendon or a swelling indicates an old partial rupture. The tendon then is opened longitudinally. Occasionally, granulation tissue is found and excised. If there are no findings in the tendon, a tenotomy may be performed.[33, 34, 35]

A tenotomy is described in an article by Martems et al.[36] The region is infiltrated with lidocaine and epinephrine. A stab wound is made just underneath the adductor longus muscle, close to the os pubis. The insertion of the gracilis muscle and a portion of the adductor brevis are sectioned subcutaneously. The adductor longus tendon is left intact. A compression bandage is then applied for 24 hours. The patient may walk after 2 days and may resume running within pain limits 5 weeks postoperatively. The usual time to return to unrestricted sports activities is 10-12 weeks. In this study, there was no loss of power in the surgical group compared with the control group.

Although surgery has traditionally been recommended for adductor tendon rupture, a question exists as to whether attachment of the proximal adductor longus tendon to the pubis is necessary for high-level physical functioniong. In a study of 19 National Football League players with adductor tendon rupture, 14 of whom were treated nonoperatively and 5 of whom underwent surgical tendon repair with suture anchors, Schlegel et al determined that the players who received nonoperative therapy tended to return to play sooner than those who were surgically treated (mean time to return: 6.1 wk vs 12 wk, respectively).[37]

Proper treatment of an acute adductor strain is important to prevent complications and development of a chronic strain. If the athlete develops chronic symptoms, his/her length of rehabilitation becomes prolonged and return to participation is delayed. A common complication that results is a tight weak adductor muscle, which is prone to recurring strains when the athlete returns to activity.

The goals of pharmacotherapy in adductor strain are to reduce morbidity and prevent complications. Agents of treatment include Celecoxib (Celebrex), nonsteroidal anti-inflammatory drugs (NSAIDs), skeletal muscle relaxants, and local anesthetics. Cyclooxygenase type-2 inhibitors(COX-2 inhibitors) are the drug of choice for this condition; in cases of severe pain, opioid analgesic agents may be prescribed. Muscle relaxants often are used to reduce muscle spasm after initial injury.

Class Summary

NSAIDs are also a drug of choice for adductor strain for this condition. In cases of severe pain, opioid analgesic agents may be prescribed. Muscle relaxants often are used to reduce muscle spasm after initial injury.

Ibuprofen (Advil, Motrin, Ibuprin, Neoprofen)

Ibuprofen is a member of the propionic acid group of NSAIDs. It possesses anti-inflammatory, analgesic, and antipyretic mechanisms of action and may be related to prostaglandin synthetase inhibition.

Naproxen (Anaprox, Naprelan, Naprosyn, Aleve)

Naproxen is used for the relief of mild to moderate pain. It inhibits inflammatory reactions and pain by decreasing the activity of cyclooxygenase, which results in a decrease of prostaglandin synthesis.

Ketoprofen

Ketoprofen is used for relief of mild to moderate pain and inflammation. Small dosages are indicated initially in small patients, elderly patients, and patients with renal or liver disease. Doses higher than 75 mg do not increase the therapeutic effects. Administer high doses with caution, and closely observe the patient's response.

Celecoxib (Celebrex)

Celecoxib primarily inhibits COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited; thus, GI toxicity may be decreased. Seek the lowest dose of celecoxib for each patient. It is extensively metabolized in liver primarily via cytochrome P450 2C9. Celecoxib is approved by the FDA to treat osteoarthritis and rheumatoid arthritis.

Although increased cost can be a negative factor, the incidence of costly and potentially fatal GI bleeds is clearly less with COX-2 inhibitors than with traditional NSAIDs. Ongoing analysis of cost avoidance of GI bleeds will further define the populations that will find COX-2 inhibitors the most beneficial.

Class Summary

Skeletal muscle relaxants are indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute painful musculoskeletal conditions.

Cyclobenzaprine (Flexeril, Fexmid, Amrix)

Cyclobenzaprine is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions.

Baclofen (Lioresal, Gablofen)

Baclofen is metabolized in the liver and excreted primarily in urine. This agent is not a controlled substance under the Drug Enforcement Administration (DEA).

Tizanidine (Zanaflex)

Tizanidine is a centrally acting muscle relaxant metabolized in the liver and excreted in urine and feces. It is used in patients with predominantly upper motor neuron involvement. It is not a DEA-controlled substance.

Carisoprodol (Soma)

Carisoprodol is a short-acting medication that may have depressant effects at the spinal cord level.

Skeletal muscle relaxants have modest short-term benefit as adjunctive therapy for nociceptive pain associated with muscle strains and are used intermittently for diffuse and certain regional chronic pain syndromes. Long-term improvement over placebo has not been established.

Class Summary

Local anesthetics are used for local pain relief.

Lidocaine (Xylocaine)

Lidocaine decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. It is used for relief of pain associated with postherpetic neuralgia and has been used for pain relief of many other types of pain generators as well.