Hip Flexor and Groin Strain
- Hip flexor and groin (adductor) strains are common injuries in athletes, especially those in sports that involve kicking, cutting, and sprinting, such as soccer, football, and ice hockey.
- •Among soccer players, groin injuries account for 8–18% of all injuries.
- •A number of muscles are involved in flexion of the hip, including the iliopsoas, rectus femoris, sartorius, tensor fasciae latae, pectineus, and the adductor muscles. The iliopsoas and rectus femoris muscles, which are innervated by the femoral nerve (L2-L4), are the major hip flexors that are most commonly involved in injuries
- The adductor muscle group is made up of the adductor longus, magnus, and brevis, along with the gracilis, obturator externus, and pectineus. All the adductor muscles are innervated by the obturator nerve (L2-L4) except the pectineus (femoral nerve, L2-L4) and the adductor magnus (both obturator and tibial nerve [L2-S3]).
- •Prior adductor or hip flexor strain, decreased strength in these muscle groups, and higher level of play have been associated with an increased risk of adductor and hip flexor injuries.
- •Returning athletes to play before they can perform pain-free, sport-specific activities can lead to prolonged recovery or chronic injury.
- •Pain localized to the proximal anterior, middle anterior, or medial thigh
- •May be an insidious onset with progressive pain or a sudden, painful event, especially after a sudden change in direction or sudden increase in acceleration, kicking, or other forceful eccentric contraction of the hip flexor or adductor muscles. Pain after hyperextension of the hip may also be reported in hip flexor injuries.
- •In an acute injury, the patient commonly reports “ripping” or “stabbing” pain in the groin or the medial thigh that is intensified with passive abduction (adductor strain) or passive hip extension (hip flexor strain). This pain is replaced by an intense dull ache.
- •In a chronic injury, the pain is often described as a diffuse dull ache that may be felt deep in the groin (iliopsoas strain), radiate distally along the anterior aspect of the thigh (rectus femoris strain), or radiate distally along the medial aspect of the thigh (adductor strain).
- •In patients with pain unrelated to a specific injury or repetitive exercise, genitourinary, gynecologic, and gastrointestinal symptoms that suggest a nonmusculoskeletal etiology should also be explored.
- •A detailed and thorough examination, along with an understanding of the anatomy, will help to distinguish hip flexor and groin (adductor) strains from other causes of groin pain
Differential Diagnosis of Groin Pain
|Groin (adductor) strain||Painful resisted hip adduction and tenderness along the adductor muscle group.|
|Hip flexor (iliopsoas or rectus femoris) strain||Painful resisted hip flexion and pain on hip flexor stretching. May have tenderness near the insertion of the iliopsoas on the femur or along the length of the rectus femoris.|
|Osteitis pubis||Palpable tenderness at the pubic symphysis; may also see loss of rotation of one or both hips, positive pubic spring test, positive lateral compression test. Radiographs, magnetic resonance imaging, and/or bone scan can help to determine the diagnosis.|
|Athletic pubalgia||Previously referred to as sports hernia, groin disruption. Suspected to occur due to disruption of the rectus abdominus insertion at the pubic bone and a weakened posterior inguinal wall. Pain located in the region of the inguinal canal, pubic tubercle, or at or near the rectus insertion. No palpable inguinal hernia. Pain increases with resistance testing of the abdominal muscles and Valsalva.|
|Obturator neuropathy/nerve entrapment||Deep ache near the adductor origin on the pubic rami that worsens with exercise and may radiate down medial thigh toward the knee. Spasm, weakness, and paresthesias of the adductors can also occur. Pain with hip abduction and external rotation and with resisted hip internal rotation (all causing nerve stretch). Electromyography or obturator nerve block can support the diagnosis. Also consider ilioinguinal, genitofemoral, and iliohypogastric nerve entrapments.|
|Pelvic avulsion fracture/apophysitis||Pain and tenderness at the anterosuperior iliac spine, anteroinferior iliac spine, pubic rami, or lesser trochanter after an acute injury. More likely in pediatric and adolescent patients. Plain radiographs can confirm fracture.|
|Stress fracture||Medial thigh or groin pain that worsens with exercise, relieved with rest. Associated with repetitive overuse, endurance athletes. Most commonly occurs at the femoral neck or pubic ramus, leading to vague pain localization. Inability to complete single-leg hop due to pain. MRI or bone scan can confirm diagnosis.|
|Intra-articular hip sources of groin pain||Wide differential that includes femoroacetabular impingement, acetabular labral injury, hip osteoarthritis, hip avascular necrosis, slipped capital femoral epiphysis, Legg-Calvé-Perthes disease. Will often see painful or limited hip internal rotation, particularly with FADIR test (flexion, adduction, internal rotation). Plain radiographs and magnetic resonance imaging can be useful for clarifying diagnosis.|
|Nonmusculoskeletal sources of groin pain||If history and exam do not suggest one of the above etiologies, consider evaluating the patient for the presence of gastrointestinal, genitourinary, or gynecologic conditions.|
- Ecchymosis or swelling can be observed at the proximal medial or anterior thigh or along the course of the adductor muscles.
- •Adductor strains
- •Palpable tenderness along the adductor muscles or near their origin along the pubic bone
- •Pain and tightness with passive stretching of the adductor muscles with hip abduction
- •Pain with resisted hip adduction
- •Hip flexor strains
- •Involving the iliopsoas
- •Palpable tenderness just medial to the anterosuperior iliac spine (ASIS) in the femoral triangle or along the psoas muscle above the inguinal ligament
- •Involving the rectus femoris
- •Palpable tenderness can be found anywhere from its origin at the anteroinferior iliac spine (AIIS) to more distally along the anterior thigh
- •Pain with resisted hip flexion
- •Pain and tightness with passive stretching of the iliopsoas and rectus femoris with hip extension or a modified Thomas test (which involves maximally flexing the contralateral hip while stretching the affected hip flexor)
- •Involving the iliopsoas
- •Imaging is generally unnecessary if history and exam suggest a hip flexor or groin (adductor) strain.
- •If bony tenderness is present at the origin of the adductor muscles (pubic rami), the origin of the rectus femoris (AIIS), or the insertion of the iliopsoas (lesser trochanter) after an acute onset of pain, plain radiographs can be useful in ruling out an avulsion fracture.
- •In cases of diagnostic uncertainty or for injuries unresponsive to therapy, ultrasound and magnetic resonance imaging (MRI) are the modalities of choice to confirm injury to these muscle groups
- Ultrasound has a sensitivity of up to 84% when compared to the gold standard of MRI for the detection of muscle strains.
- •Advantageous in the ability to use sonopalpation to dynamically reproduce a patient’s pain with palpation of a sonographically abnormal finding
- •MRI can yield prognostic information about muscle strains and tears. Although there are no studies to date involving specific prognosis for adductor or iliopsoas strains seen on MRI, tears involving larger cross-sectional areas and tears located at specific locations (such as the central tendon of the rectus femoris) are generally associated with prolonged recovery.
- •None are required for hip flexor or adductor strains.
- •If the history or physical examination suggests a nonmusculoskeletal source of the patient’s groin pain, additional studies may be indicated.
- •Treatment principles are similar for both hip flexor and adductor strains. Rehabilitation should follow a stepwise progression through the following phases:
- Phase 1: Range of motion and isometric exercises
- •Range of motion exercises can be performed multiple times per day. Avoid exercises that cause moderate to severe pain (>5/10).
- •Isometric exercises should be performed daily, with increasing resistance and increasing duration as tolerated.
- •This phase should also include PRICE (Protection, Relative Rest [avoid painful activities, consider using crutches for a few days in acute strains], Ice, Compression, Elevation).
- •Short courses of nonsteroidal antiinflammatory drugs can also be given.
- •Modalities such as electrical stimulation and massage can help to alleviate muscle spasm.
- •Once the patient is able to engage in normal activities of daily living without pain and has no pain with range of motion and isometric exercises, they can progress to the next phase.
- •Phase 2: Progressive strengthening
- •Eccentric and concentric exercises with gradually increasing load while varying repetitions to achieve increased strength and neuromuscular coordination. Exercises should occur three times a week with at least one rest day in between each session.
- •Aerobic exercises can be introduced but should avoid cutting or aggressive changes in speed.
- •Once the patient can straight-line run and advance through the strengthening program without pain, they can progress to the next phase.
- •Other biomechanical abnormalities should be sought and corrected if found.
- •Phase 3: Proprioception, dynamic sport-specific exercises, and return to play/activity
- •Return to play/activity goals
- •Patient has restored the vast majority of his or her strength compared with the contralateral side.
- •Patient has pain-free full range of motion.
- •Patient can perform sport-specific exercises without pain or alteration of mechanics.
- •Return to play/activity goals
When to Refer
- •Although the vast majority of adductor and hip flexor injuries can be successfully managed conservatively, refer patients with chronic hip flexor or adductor strains that fail to respond after at least 6 months of conservative treatment.
- •Experienced orthopaedists or sports medicine physicians may have experience in treating these conditions with advanced injections (prolotherapy, platelet-rich plasma [PRP], etc.), dry needling, or acupuncture.
- •Rare indications for surgical referral include chronic tendinopathy refractory to the aforementioned interventions, where a tenotomy may be considered, and a large bony avulsion at the tendon origin or insertion.
- •Many athletes with minor injuries advance rapidly through their rehabilitation program and are able to return to sports in less than 1 week. More significant injuries may take 4 to 8 weeks for recovery and require careful advancement through their rehabilitation program.
- •In chronic injuries, rehabilitation may take anywhere from 2 to 6 months before return to sports.
- •The patient must be pain free with sports-specific activities to return to sports to avoid risk of reinjury or chronic injury.
- •The use of corticosteroid injections in hip flexor and adductor strains is controversial. Although corticosteroids are likely to improve pain and inflammation in the short term, there is concern that steroids could weaken the tendon and predispose to chronic or recurrent injury.
- •Counsel patients that these injuries respond well to conservative therapies and will benefit from long-term maintenance of hip flexor and adductor strength.
- •Follow physician, physical therapist, and/or athletic trainer instructions closely with respect to the type, quantity, and timing of exercises and activities that are appropriate for the stage of injury.
- •Counsel patients regarding symptoms that may suggest an alternative diagnosis or require immediate evaluation.
Considerations in Special Populations
- •Those caring for athletes (particularly in sports involving kicking, cutting, and sprinting) will commonly encounter this condition.
- •Treatment for athletes with hip flexor and adductor injuries requires a team approach and an understanding of the athlete’s practice and competition schedule.
- •Hip flexor and groin strains are recurrent in up to 50% of athletes, with highest rates of recurrence in ice hockey.
- •Studies have shown mixed results regarding the efficacy of preseason and in-season exercise programs designed to prevent groin pain in competitive athletes.
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