When Groin Pain Is More Than 'Just a Strain': Navigating a Broad Differential
Joseph J. Ruane, DO; Thomas A. Rossi, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 4 - APRIL 2021
In Brief: Most groin pain results from musculotendinous injuries, but not all groin pain signifies simply a pulled muscle. The pain can stem from one or more musculoskeletal or nonmusculoskeletal origins, such as avulsion fracture, osteitis pubis, or hernia. While acute causes are often readily identified, chronic groin pain can present a diagnostic challenge. Paying close attention to the history can help identify acute causes such as strains and avulsion fractures; determining the location and nature of the pain can also help with diagnosis. Conservative treatment is often effective for treatment of acute injuries such as strains and avulsion fractures.
While the most common cause of groin pain in active patients may be a garden-variety muscle strain, less common causes add up to a wide differential. Broadly considered, the pain can be thought of in terms of onset and chronicity (acute vs chronic), and in terms of its musculoskeletal or nonmusculoskeletal origin (table 1).
Acute groin pain is a common result of musculoskeletal injuries that can occur with the sharp, cutting movements of kicking and running sports. These injuries are especially common in soccer but are also seen in racket sports, basketball, hockey, volleyball, football, and other sports.
Chronic groin pain, in contrast, may suggest nonmusculoskeletal causes such as hernias, lymphadenopathy, infections, sexually transmitted diseases, or even cancer.
Directions for Diagnosis
As in all medicine, the diagnosis of groin pain begins with a good history. Paying close attention to subtle clues in the patient's history often leads to the correct diagnosis. With a sudden change of direction while running, a forceful eccentric contraction of a muscle can occur instead of the intended concentric contraction, causing the most common groin injury—a muscle strain. Overstretching a muscle can also induce a strain (1,2). A forceful muscle contraction in an adult might strain the muscle unit, while in an adolescent the same action can cause an avulsion fracture (3). Symptoms that occur with a change of training regimen suggest a stress fracture. A detailed history of injury or trauma to the area can lead you to the source of pain (see "Case Study: A Surprising Cause of Groin Pain in a Female Runner," below).
Determining the site of pain will further assist in the diagnosis. Is it localized—such as in the medial thigh, over the pubis, over an apophysis, or in the testes—or is it diffuse? Is there a referral pattern such as into the scrotum, into the knee, or along a specific dermatomal area; or is the pain nonradiating? Movements that reproduce or intensify the pain should also be sought.
Perhaps the most important task in diagnosis is delineating whether the injury is acute or chronic. While acute causes are often readily identified, chronic groin pain may suggest myriad diagnoses, many with vague and overlapping signs and symptoms.
For chronic groin pain, the physician needs to inquire about urinary symptoms, night pain, rheumatologic components, or systemic symptoms. Chronic, insidious groin pain can indicate a nonmusculoskeletal cause and requires a more complex diagnostic approach.
If groin pain persists despite treatment, other diagnoses must be entertained. A multidisciplinary strategy may be required, and secondary diagnoses are not uncommon (4-6).
Following are musculoskeletal and nonmusculoskeletal causes of groin pain, with clinical features and treatments described.
Primary Musculoskeletal Causes
Active people who incur an acute injury with a sharp, cutting motion usually experience pain in the proximal medial thigh and, possibly, swelling. Such patients usually have only minor discomfort with walking, but their pain increases with running or cutting. Musculotendinous injuries most often involve the adductor longus muscle but can also include the iliopsoas, rectus femoris, sartorius, or gracilis muscle (figure 1) (1,2,4,7).
Most groin injuries in active people are musculotendinous (5).
Strains. The most common musculoskeletal cause of groin pain is a muscle strain, which occurs when a muscle is stretched beyond its normal capability or encounters an unexpected opposing force. Signs and symptoms include acute pain over the proximal muscles of the medial thigh, swelling, and, occasionally, bruising. Also present will be the classic musculotendinous injury triad: tenderness to palpation, pain with resistance, and pain with passive stretching.
Imaging procedures are usually unnecessary in simple muscle strains. If obtained, they are usually done to rule out concomitant or more severe injuries (8). Ultrasound should be used with caution because it can promote bleeding in the acute injury and mutagenesis, and the treatment area is often close to reproductive organs.
The treatment of muscle strains consists of rest from aggravating activities for the first 1 to 2 weeks (7). Ice is used initially, and heat can be used after the first 48 hours. Compression shorts can provide symptomatic relief and expedite return to play. If compression shorts are not available, a hip spica wrap can provide both warmth and support. We like to use nonsteroidal anti-inflammatory drugs (NSAIDs) for the first 7 to 10 days to limit inflammation and control pain in order to facilitate rehabilitation.
When inflammation subsides, patients can start a stretching program. During the stretching phase of rehabilitation, patients are encouraged to maintain cardiovascular fitness with aerobic exercises that do not exacerbate their pain. A strengthening program consisting initially of low-intensity isotonic exercises can follow the stretching phase (7). Surgical repair for musculotendinous injuries has been tried with varied success, and should be the decision of an orthopedist familiar with the techniques (9,10).
Adductor tendinitis. Tendititis is often caused by chronic overloading of a musculotendinous unit, resulting in microscopic tears in the tissue substance. If this happens in the adductor muscle, the patient experiences pain and stiffness in the groin region that is often worse after an exercise bout.
There is local tenderness to palpation, and adductor tendinitis is often difficult to differentiate from an adductor strain on physical exam. Pain may at times radiate along the medial thigh or toward the rectus abdominis. Treatment centers on allowing the tendon unit to heal without further overload.
Avulsion fractures. Avulsion fractures occur in adolescents, especially teenagers, and are more common in the mid to late teens when muscles significantly increase in contractile strength. These fractures occur in one of several apophyses in the hip area (figure 2) (11). Avulsions are usually caused by an unexpected, explosive contraction of the muscle. Direct trauma is a much rarer cause (3).
A typical history is that of a hurdler or sprinter who experienced a "pop" and acute pain while "kicking it out" at the end of a race. A limp with an avulsion fracture is a clue that it is severe (3). The patient will have pain on palpation at the site of the injury and with stretching of the involved muscle.
Plain radiographs are usually diagnostic (1,3,7). A small piece of bone is observed near the attachment site of the tendon. This should not be confused with calcification in the tendon unless a chronic process has been elucidated in the history.
Most avulsion fractures are treated conservatively, beginning with relative rest. Ice and NSAIDs are used to control pain and swelling, and crutches may be needed for the first several days. Return to sports is allowed when the patient is pain free, which can take 4 to 6 weeks depending on the site of the avulsion.
Stress fractures. Repetitive forces on the long bones can lead to stress fractures. The most common sites causing groin pain include the pubic ramus and femoral neck. These injuries usually occur in long-distance runners, whose sport subjects these bones to repetitive stresses. They can occur when there is a change in equipment, especially running shoes. Sudden increases in training intensity or duration can also overwhelm the natural physiologic response to stress and weaken bony architecture. Changing to a harder training surface such as pavement has also been associated with stress fractures (12).
The active patient who has a chronic ache or pain in the groin, buttock, and thigh can have a pubic ramus stress fracture (8); a similar ache or pain with decreased range of hip motion (specifically internal rotation in flexion) may indicate a femoral neck stress fracture. Plain radiographs are initially negative, but a bone scan can show increased isotope uptake at the site of the stress fracture early on (4-8,13). Serious complications can arise if a femoral neck stress fracture is not recognized and the athlete continues to train despite pain. Avascular necrosis of the femoral head, nonunion, and varus deformity of displaced fractures have all been reported. Several classification protocols exist; all are based on defining the femoral neck stress fracture as compressive or distracted in nature, with the latter posing a greater likelihood of disability.
If suspicion is high, thorough investigation is mandatory. Patients with negative radiographs should be treated with complete non-weight-bearing until a bone scan can be completed. If there is radiographic evidence of a stress fracture, then magnetic resonance imaging (MRI) or computed tomography (CT) scans should be obtained to determine its extent and type. Involvement of an orthopedist is prudent early on if plain radiographs show a lesion (12).
Femoral neck stress fractures that are nonoperative in nature are treated with strict non-weight bearing until the patient is pain free. Rehabilitation and return to sport must be gradual, allowing for adequate remodeling of the femoral neck. Water exercise is excellent for rehabilitation, and various pool running progressions have been described. A progression from water to cycling to a walk-run program is advised (12).
Treatment for other stress fractures consists of relative rest and avoidance of aggravating activities. Six to 8 weeks away from running is often needed for these fractures to heal.
Secondary Musculoskeletal Causes
Pubic instability. Pubic instability results in excess motion at the pubic symphysis. Trauma to the pelvis or significant unilateral axial loads to the lower extremity can lead to instability. Pain is felt in the pubis, groin, or lower abdomen and is sometimes accompanied by a clicking sensation with certain lower-extremity movements. A flamingo view radiograph confirms the diagnosis and is considered positive when alternating weight-bearing views show a shift of 2 mm or more in the pubic symphysis.
Treatment includes traditional conservative measures to relieve symptoms, such as physical therapy, NSAIDs, and compression shorts. In refractory cases, surgical intervention including bone grafts and plating have been described (14).
Osteitis pubis. Some believe osteitis pubis to be a self-limiting disease of the pubic symphysis (13). It is believed that repetitive twisting and cutting motions initiate a lytic response caused by traction of the adductor and gracilis muscles.
Symptoms include pain over the pubic symphysis or medial groin region that is increased with resisted adduction of the thigh. Because pain can be diffuse around the abdomen, groin, hip, or thigh (15), this entity can be confused with other musculoskeletal conditions.
Plain radiographs may show irregularity, sclerosis, and widening of the pubis consistent with osteolysis, although they often do not provide good correlation with the clinical exam (3,15,16). A bone scan typically shows increased uptake unilaterally or bilaterally at the pubic bones (13,15,16).
Treatment consists of relative rest with ice and NSAIDs initially, followed by stretching exercises.
If symptoms persist, a treatment regimen described by Batt et al (15) may be undertaken, consisting of betamethasone injection into and around the pubic symphysis, followed by NSAIDs. With injections, utmost care must be taken with needle placement as bladder perforation or injection into the abdominal cavity is possible. A repeat injection can be done 2 weeks later, if needed, when a stretching program is begun.
The patient can return to play gradually when pain free. Osteitis pubis can sometimes take as long as 9 months to resolve with conservative care. Reported rates of recurrence and failure to return to previous levels of competition have been as high as 25%, and may be higher in men (16).
Bursitis. Bursitis usually develops acutely from trauma or can be chronic when overuse of the overlying muscles leads to inflammation.
Symptoms include pain over the site of the bursa. (Iliopsoas tendinitis or bursitis may cause pain in the lower abdomen, anterior thigh, or groin, making it tricky to diagnose.) Diagnosis is usually clinical, but is best confirmed when anesthetic infiltration relieves the symptoms.
Treatment can consist of an injection of cortisone, an anesthetic, or both.
Avascular necrosis. Groin pain can be caused by avascular necrosis of the femoral head following hip trauma. Medications (especially corticosteroids), alcohol abuse, and systemic disease can also cause avascular necrosis. Avascular necrosis of the femoral head that occurs in children 5 to 8 years old, especially boys, is called Legg-Calvé-Perthes disease. Symptoms include inguinal pain on internal rotation of the hip and decreased hip range of motion.
Plain radiographs show subchondral lucency around the superolateral femoral head (the crescent sign) (8). Other early radiographs may reveal increased density at the femoral epiphysis, and later, a mottled, moth-eaten appearance of the femoral head may be seen. MRI can aid in diagnosis (13), and in the elderly population should include a view of the opposite hip, as avascular necrosis is more likely to occur bilaterally in this population.
Treatment ranges from conservative measures focused on pain relief to total hip replacement. Regardless of severity, referral to an orthopedic surgeon is warranted.
Myositis ossificans. A direct blow to a muscle or significant muscle strain can lead to the development over several months of myositis ossificans. Initial bleeding leads to hematoma formation that later calcifies within the substance of the muscle, restricting its extensibility.
Symptoms and signs include pain and decreased range of motion in the involved muscle. A palpable mass is often detected within the substance of the muscle once calcification has begun.
Radiographs can be negative up to 5 weeks after trauma and before calcific changes are seen in the soft tissues. A discrete margin between the cortex of the involved bone and the calcified area helps distinguish heterotopic bone formation from other pathologic entities. Osteogenic sarcoma is sometimes difficult to differentiate from heterotopic bone on radiographs. However, it is contiguous with, rather than distinct from, the adjacent cortices. Heterotopic bone and osteogenic sarcoma biopsy specimens share similar histologic features, which can further confound the diagnosis. A triple-phase bone scan can help to make the diagnosis earlier by revealing increased uptake within soft tissues adjacent to the bones.
Treatment consists of moderately aggressive active or passive range-of-motion exercises. Care must be taken not to overstretch the muscle and cause further bleeding. Keeping the muscle in a lengthened position in the early phase can help decrease the incidence of heterotopic bone formation. For the quadriceps muscles, this can be accomplished by wrapping the affected area in an elastic bandage with the knee in maximum flexion for the first 24 hours after the trauma. NSAIDs are avoided or used sparingly in the first 2 days to limit hematoma formation but are the drugs of choice to limit calcification later on. Indomethacin has historically been associated with treating myositis, but it is not necessarily any more effective than other NSAIDs.
Nerve entrapment. Nerve entrapments in the inguinal region, including genitofemoral, ilioinguinal, and obturator nerves, have all been described as causes of chronic groin pain. Mechanisms of entrapment or injury include local hernia into the nerve tunnel, nearby inflammatory or infectious processes, or trauma or scarring from surgery or nearby injuries. Thick fascial bundles causing stenotic canals have also been described as a mechanism (17). The ilioinguinal, genitofemoral, iliofemoral, or lateral cutaneous nerves are most commonly involved.
The patient describes a burning or shooting pain in the distribution of the nerve. Light touch sensation in the medial groin can be altered, or pain can be exacerbated by hyperextension at the hip joint. Occasionally, there is tenderness near the anterior superior iliac spine where the ilioinguinal nerve pierces the fascia and is subject to entrapment. An electrodiagnostic study can help in the diagnosis.
Treatment consists of infiltration around the nerve site with a local anesthetic (4). Topical creams such as capsaicin can also be used in the treatment of painful dysesthesias. After several weeks, the medicine can be discontinued to see if the dysesthesias have subsided.
Musculoskeletal Causes in Youth and Elderly
Slipped capital femoral epiphysis. Insidious groin pain that develops in the 8- to 15-year-old child or adolescent should make the physician suspect slipped capital femoral epiphysis (see "Case Study: Hip Pain in a Young Football Player," below). The typical adolescent will be an obese or rapidly growing boy who has not yet begun puberty.
The patient has inguinal pain with hip motion, and pain made worse with physical activity. He or she usually walks with a limp and holds the leg in external rotation. Plain radiographs, especially frog-leg lateral views, are usually diagnostic (13).
Treatment involves discontinuing all athletic activity and referring the patient to an orthopedic surgeon.
Osteoarthritis. Osteoarthritis of the femoral head is a degenerative disease that occurs most often in elderly patients. Complaints include inguinal pain with hip movement, especially internal rotation. Plain films are usually diagnostic (4).
Treatment can be conservative with nonnarcotic analgesics or NSAIDs for pain relief. If intractable pain affects the patient's quality of life, a total hip replacement can be considered.
General Nonmusculoskeletal Causes
Hernia. The recent literature shows hernia to be an often-overlooked cause of chronic groin pain (4-6,13,18,19). In his review of chronic groin pain in 189 athletes, Lovell (4) noted that over 50% had incipient hernias. The debate continues over the significance of clinically undetectable hernias, but surgical repair is producing excellent results in cases of recalcitrant groin pain.
The most common type of hernia is a direct inguinal hernia, which is the result of a tear or weakness of the posterior wall of the inguinal canal. This produces chronic episodic pain just above the pubic tubercle. Initially the pain occurs after activity, but it increases and occurs during activity as the problem progresses. Pain can be unanticipated and sharp, with abrupt increases in abdominal pressure (18). The pain can also radiate into the proximal medial thigh or the scrotum in males.
A palpable mass may or may not be detected. Patients can be asked to perform maneuvers such as coughing or tensing muscles to increase intra-abdominal pressure and make a mass more prominent (18). In males, the scrotum should be invaginated so that the inguinal rings are palpated. Tension on the abdominal wall may also elicit discomfort. A tear or strain of the conjoined tendon—the fused aponeurosis of the internal oblique and transversus abdominis—can cause pain at the external inguinal ring or at the pubic crest area (4). The pain from hernias responds poorly to traditional measures, including prolonged rest, and it usually resurges soon after return to activity.
Herniography, a procedure that has been used in Europe with success, can be an option when a hernia is the suspected cause of chronic groin pain and surgical treatment is being considered (1,4-6,18). The procedure involves injecting a contrast medium into the pelvic cavity, obtaining radiographs, and looking for anterior extension of the dye into the inguinal area (4,13).
Lymphadenopathy. Lymphadenopathy can be caused by an infection in the trunk or lower extremities, or by a sexually transmitted disease. The physician can find palpable lymph nodes just below the patient's inguinal ligaments. Lymphadenopathy may be associated with fever, chills, or discharge, depending on the specific cause of the lymphadenopathy.
Treatment usually consists of antibiotics for the underlying infection. If lymphadenopathy persists despite acute treatment, an underlying neoplasm should be suspected, although it is not as common. A rule of thumb is that tender lymph nodes suggest infection and nontender nodes a neoplasm.
Nonmusculoskeletal Causes in Males
Genital swelling or inflammation. Epididymitis, hydroceles, and varicoceles may cause groin pain in males.
Epididymitis is caused by sexually transmitted diseases in younger active patients, and usually by gram-negative organisms in older patients. The inflamed epididymis is often exquisitely tender over the superior aspect of the testes.
A hydrocele is a fluid-filled mass around the testes, and symptoms usually involve pain in the lower spermatic cord region. Transilluminating the scrotum with a penlight can facilitate diagnosis of a hydrocele.
A varicocele is usually located on the left and is a rubbery, elongated mass around the spermatic cord (13). This painful dilation of the venous plexus can cause infertility.
If infection is identified, treatment consists of appropriate antibiotics. Otherwise, referral to a urologist is prudent.
Testicular torsion or rupture. Testicular torsion or rupture is considered a medical emergency. It has an acute onset and, in the case of a rupture, is usually preceded by trauma. Signs and symptoms include swelling and severe pain in the scrotum, often accompanied by nausea and vomiting. The testes may be hard on palpation or may not be palpable at all.
The patient should be referred to a urologist immediately if torsion or rupture is suspected.
Prostatitis. Prostatitis can cause dysuria as well as a purulent discharge in male patients. Both urinalysis and a culture of the prostatic secretion will demonstrate infection and/or inflammation and aid diagnosis. A rectal exam will reveal a tender, soft, and irregular prostate (6). Prostatitis has been correlated with symphysitis, and it must be considered in an older man who has chronic symptoms. The belief is that the infection in the prostate can trigger a reactive arthritis (20). Prostatitis can also mimic adductor longus tendinitis, which is differentiated by the rectal exam.
Treatment consists of appropriate antibiotics to treat the infection and NSAIDs to reduce pain and inflammation.
Testicular cancer and other neoplasms. Testicular cancer has an insidious onset in men aged 18 to 36. Signs and symptoms include palpation of a hard mass on the testis and, possibly, a tender testis.
Ultrasound can aid in the diagnosis, and patients should be referred to a urologist. The suspicion of neoplasm must always lurk when obvious causes are becoming less likely.
Nonmusculoskeletal Causes in Females
Ovarian cysts. Active female patients with no obvious cause for perineal or groin pain should have a pelvic exam. Ovarian cysts have an insidious onset and produce groin or perineal pain.
An adnexal mass can sometimes be palpated on exam. Ultrasonography can help make the diagnosis (13), and treatment consists of referral to a gynecologist.
Urinary tract infections. Urinary tract infections can occur, especially in female athletes who do not maintain adequate hydration. Symptoms include burning with urination, itching, and frequent urination. Urinalysis with culture and drug sensitivity will confirm the diagnosis (6,13), and treatment consists of a short course of appropriate antibiotics.
Pelvic inflammatory disease. Pelvic inflammatory disease is most often the result of a sexually transmitted disease. A patient can become gravely ill if treatment is delayed. The patient may have fever, chills, and purulent discharge in additon to groin pain.
A pelvic exam with cultures can help to make the diagnosis. Treatment usually consists of intravenous antibiotics and referral to a gynecologist.
Meeting the Challenge
Diagnosis and treatment of an active patient who has groin pain can often offer a much deeper challenge than meets the eye. Referral to a specialist is often helpful, and it may take more than one referral or specialist. Finding the right treatment not only will help active patients return to their sport, but can also help them avoid long-term pain.
Case Study: A Surprising Cause of Groin Pain in a Female Runner
A 33-year-old woman presented with right groin pain. Three weeks earlier she had had a dirt bike accident but did not recall any significant impact to the pelvic region. She was an avid runner and was having difficulty returning to her sport. She was treating her "bad groin pull" with heat and over-the-counter analgesics. She also had right-side sacroiliac pain, and discomfort in the right anterior thigh with running.
Clinical examination revealed tenderness and spasm of the proximal adductor mass on the right, with significant tenderness at the insertion. There was pain and weakness with activation of that adductor muscle group. The right sacroiliac joint was tender, with tenderness extending a few centimeters into the sacrum.
An anteroposterior pelvis radiograph was obtained (figure A), mostly to inspect the sacrum and sacroiliac joint. A minimally displaced transverse fracture of the right superior pubic ramus was discovered, which likely resulted from the trauma at the time of the dirt bike accident. As the patient had already been ambulatory for 3 weeks, treatment consisted of continued protected weight bearing. At 8 weeks postinjury she was pain free with ambulation, and she gradually returned to running with no further incident.
Case Study: Hip Pain in a Young Football Player
A 14-year-old boy had right hip pain for 2 months. Radiographs (figure B) taken 1 month earlier had been interpreted as negative; he had then begun 3 weeks of physical therapy for a "chronic groin pull." He was removed from football just prior to his visit because he was unable to run.
The radiographs demonstrate a chronic grade 1 slip of the capital femoral epiphysis. This patient was a slightly overweight prepubescent male who walked into our office with the classic antalgic gait, holding his leg in external rotation. While it was probably not so obvious in the early stages, this case demonstrates why it is important to keep a broad differential in mind, especially in adolescents.
The patient was referred immediately to an orthopedic surgeon, and open reduction with screw fixation was performed the following day. At 2 weeks postsurgery the patient was healing well with no evidence of recurrence.
Dr Ruane is a family physician specializing in the diagnosis and treatment of sports-related injuries at SportsMedicine Grant in Columbus, Ohio. Dr Rossi is a physiatrist at Physical Medicine Associates, Inc, and has completed a fellowship in primary care sports medicine at SportsMedicine Grant, both in Columbus. Drs Ruane and Rossi are members of the American College of Sports Medicine. Address correspondence to Joseph J. Ruane, DO, SportsMedicine Grant, 323 East Town St, Columbus, OH 43215; e-mail to [email protected].
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