Groin Strain

Strain of the adductor muscle group (the adductor longus in about 60 to 70%, then adductor brevis, gracilis, pectineus and adductor magnus), usually at the proximal musculotendinous junction near the pubic attachment, from sudden forced abduction or resisted adduction (kicking, sprinting, change of direction).

• It is one of the commonest injuries in football, ice hockey, rugby, hurling and other sports that need rapid cutting. Groin injuries account for about 10 to 18% of football injuries, and adductor strain is the most common cause of groin pain in athletes.
• Risk factors: previous groin injury, reduced adductor strength compared with abductors (adductor to abductor ratio below 80%), reduced hip range of motion, high training load, a short preseason, age, and core weakness.
• Other conditions often coexist and cause persistent groin pain: femoroacetabular impingement, athletic pubalgia (sports hernia), osteitis pubis, and hip labral tears.
• Grades: 1 (minor, no strength loss), 2 (partial tear, with strength loss), 3 (complete rupture or avulsion).

• Sudden pain in the medial groin and proximal inner thigh, sometimes with a snap, often limiting running and kicking. Pain is worse on adduction against resistance, sprinting, stretching, coughing and sitting up.
• Tenderness at the adductor origin on the pubis and along the muscle belly, pain on passive abduction stretch and resisted adduction (squeeze test with the knees at 0 degrees, 45 degrees and 90 degrees of hip flexion), and bruising in major tears. Grade 3 tears may have a palpable gap.
• Differential diagnosis: femoroacetabular impingement and hip labral tear, osteitis pubis (pain at the pubic symphysis, with a positive symphysis tenderness), athletic pubalgia (pain on sit up and cough, weak posterior inguinal wall), inguinal and femoral hernia, iliopsoas tendinopathy or snapping hip, stress fracture of the femoral neck or pubic ramus, avulsion fracture (adolescents), referred pain from the lumbar spine or sacroiliac joint, obturator nerve entrapment, testicular and urological causes (testicular torsion, epididymitis, kidney stone), and hip osteoarthritis.
• Red flags: severe pain with inability to weight bear (stress fracture), pain with fever or systemic illness (septic arthritis, osteomyelitis of the pubis), testicular pain, a lump that does not reduce (hernia), and night pain with weight loss.
• Complications: chronic groin pain, recurrence (about 15 to 30%), adductor tendinopathy, enthesopathy, and long time lost from sport.

• Clinical examination: hip range of movement (especially internal rotation), adductor squeeze test (pain and weakness), resisted hip flexion and abdominal sit up, palpation of the pubic tubercle, symphysis and inguinal canal (with cough impulse), and lumbar spine and neurological examination.
• Imaging is not needed in a typical acute strain. For persistent or atypical groin pain beyond 3 to 4 weeks: X-ray of the pelvis (anteroposterior) and a frog leg lateral hip (to show impingement morphology, symphysis changes, stress fracture and arthritis), ultrasound (adductor tear, hernia, bursitis), and MRI (best to show adductor tears, pubic bone marrow oedema, stress fracture, labral tear and athletic pubalgia).
• Intra articular local anaesthetic injection can separate hip joint pain from extra articular pain.
• Check urine and testicular examination in men, and gynaecological causes in women, if the diagnosis is uncertain.

• First 48 to 72 hours: relative rest, ice for 10 to 15 minutes every 2 to 3 hours, compression shorts, and avoidance of painful stretching. Crutches for grade 2 to 3 injuries if walking is painful.
• Analgesia: paracetamol 1 g orally 6 hourly, with ibuprofen 400 mg orally 8 hourly with food for 3 to 5 days, or topical diclofenac 1% gel 2 to 4 g 3 to 4 times daily.
• Progressive rehabilitation (the main treatment, an active programme gives far better results than rest and passive therapy):
  • Early: pain free isometric adduction (squeeze a ball between the knees, 5 seconds hold, 10 repetitions, several times daily), gentle range of movement, and walking.
  • Intermediate: progressive adductor strengthening (side lying adduction, Copenhagen plank in stages from short lever to long lever, resisted cable adduction), core stability, hip abductor and gluteal strengthening, and stationary cycling.
  • Advanced: straight line running progression, then sprints, change of direction, kicking, and sport specific drills. Maintain strengthening twice weekly.
  • Return to sport when there is no pain on palpation or the squeeze test, full pain free hip range, adductor strength at least 90% of the other side (or an adductor to abductor ratio over 80%), and tolerance of full training. Typical return: grade 1, 1 to 2 weeks. Grade 2, 3 to 6 weeks. Grade 3, 6 to 12 weeks or more.
• Chronic adductor tendinopathy: loading programme for 12 weeks, shock wave therapy (3 to 5 weekly sessions), and platelet rich plasma (evidence limited). Corticosteroid injection near the enthesis may give short term relief, but risks tendon weakening.
• Surgical treatment: adductor tenotomy for chronic refractory pain (after 6 to 12 months of rehabilitation), repair for complete proximal avulsion in athletes (best within 4 to 6 weeks), hernia repair for athletic pubalgia (open or laparoscopic), and hip arthroscopy for femoroacetabular impingement or labral tear. Results are good in selected patients.
• Osteitis pubis: relative rest and rehabilitation, with corticosteroid injection into the symphysis for refractory pain (triamcinolone 20 to 40 mg with lidocaine 1% 2 to 3 mL), and rarely surgery.
• Prevention: the adductor strengthening programme (Copenhagen exercise 2 to 3 times weekly for 4 to 8 weeks of pre-season, then once weekly), hip mobility, and load management reduce groin injury by about 40 to 50%.
• Special groups:
  • Adolescents: avulsion injuries of the pubis or ischium need X-ray, and heal with rest in most.
  • Women: consider gynaecological, urinary, hip and pelvic floor causes, and pregnancy related symphysis pubis dysfunction.
  • Elderly: consider hip osteoarthritis and fracture, and avoid NSAIDs in renal impairment or heart failure.
  • Pregnancy: pelvic support belt, rest, physiotherapy and paracetamol. Avoid NSAIDs after 20 weeks.
• Follow up: review at 1 to 2 weeks, then every 2 to 4 weeks until return to sport. Refer to sports medicine or orthopaedics for persistent pain beyond 6 weeks, suspected hernia, impingement or stress fracture, or recurrent injury.