Insertional tendinopathy

Insertional tendinopathy is a common disorder caused by repetitive tendon strain and subsequent poor tendon healing. Tendinopathies are typically seen in athletes and people who regularly perform repetitive movements (e.g., typing, assembly-line work, etc.). The Achilles, patellar, humeral epicondylar, and rotator cuff tendons are most commonly affected. Tendinopathies are characterized by pain, especially on movement, and thickening of the affected tendons. The diagnosis is usually established clinically, but can be confirmed with tendon thickening, which is detectable on ultrasound and MRI. Imaging, including x-ray, may also be indicated to rule out possible associated trauma of the bone. Conservative treatment with rest and physiotherapy is successful in most cases, but corticosteroid injections can be used short-term if these methods fail. Surgical debridement of scarred tendon tissue is reserved for patients who do not improve despite at least 6 months of conservative treatment.

• Age: > 35 years ^[1]
• Sex: ♂ > ♀ (esp. in patellar tendinitis) ^[2]

Epidemiological data refers to the US, unless otherwise specified.

• Overuse or overload injury (repetitive, excessive strain), degeneration ^[3]
• Skeletal abnormalities with strain on tendons (e.g., genu varum)
• Acute trauma (laceration, rupture)
• Risk factors
  • Occupation: athletes, jobs requiring manual labor or repetitive movements involving the same muscle
  • Errors in physical training (e.g., sudden increase in exercise intensity, inadequate rest, hard/uneven training grounds, ill-fitting/inappropriate footwear)
  • Previous tendon injuries
  • Recent use of fluoroquinolones

• Contraction of a skeletal muscle → transmission of force through the tendon to the bone at the point of tendon insertion
• Repetitive strain → microtrauma of the tendon → improper healing → disorientation of the tendon's collagen fibers → tendinopathy
• Hypovascularity → predisposition to hypoxic tendon degeneration ^[4]

Unlike in cases of tendinitis or tenosynovitis, inflammation plays a negligible role in the development of tendinopathy.

Insertional tendinopathies of the upper limbs

• Lateral epicondylitis (tennis elbow) ; ^[5]
  • Definition: overuse injury of the hand, esp. finger extensor tendons which originate in the lateral humeral epicondyle ^[5]
  • Etiology
    • Most commonly due to repeated or excessive pronation/supination and extension of the wrist (e.g., backhand shots in racket sports)
    • Can also be idiopathic
  • Clinical features
    • Pain and tenderness over the lateral epicondyle and along extensor muscles
    • Thickening of the tendons
    • Tennis elbow test: examiner holds the patient's hand with the thumb placed over the lateral epicondyle → the patient makes a fist, pronates the forearm, deviates radially, and extends the fist against the examiner's resistance → test is positive if pain is elicited over the lateral epicondyle ^[5]
• Medial epicondylitis (golfer's elbow)
  • Definition: overuse injury of the hand, esp. finger flexor tendons which originate in the medial humoral epicondyle
  • Etiology
    • Most commonly due to repeated wrist flexion and forearm pronation (e.g., shots in playing golf)
    • Can also be idiopathic
  • Clinical features
    • Pain over the medial epicondyle and along the flexor muscles, increases with activity
    • Thickening of the tendons
    • Test: Pain is elicited on asking the patient to flex the wrist against resistance, with the elbow held in extension.
• For rotator cuff tendinitis, see “Soft tissue lesions of the shoulder.”

An EXTended game of tennis will ruin the Lawn: repeated EXTension of the elbow (e.g., in tennis) causes Lateral epicondylitis.
A FLexible game of golf allows Mulligans: repeated FLexion of the elbow (e.g., in golf) causes Medial epicondylitis.

Insertional tendinopathies of the lower limbs

• Iliotibial band syndrome: a common overuse injury of the distal portion of the iliotibial band (over the lateral femoral epicondyle)
  • Etiology: repetitive flexion and extension of the knee (e.g., from running, cycling)
  • Clinical features
    • Pain in the lateral knee (due to friction of iliotibial band against femoral epicondyle)
      • Sharp pain when the foot strikes the ground
      • Dull, constant pain at rest
      • Possible swelling at distal iliotibial band
    • Noble test: patient lies on their side and the examiner passively flexes the patient's leg while exerting constant pressure on the lateral femoral epicondyle with their thumb; test is positive if pain is elicited
• Patellar tendinitis (jumper's knee) ^[6]
  • Definition: overuse injury of the patellar tendon at the distal portion of the patella
  • Etiology: repeated jumping (e.g., volleyball, basketball)
  • Clinical features
    • Usually unilateral but can be bilateral
    • Commonly seen in adolescents ^[6]
    • Pain over the anterior aspect of the knee, which worsens with running/walking uphill or when moving after prolonged sitting/standing
    • Tenderness on applying pressure to the inferior border of the patella
• Achillodynia (Achilles tendinopathy)
  • Definition: overuse injury of the Achilles tendon
  • Etiology: athletes/individuals who have recently increased their exercise intensity
  • Clinical features: pain and tenderness 2–6 cm above the insertion of the Achilles tendon ^[7]
• Osteitis pubis
  • Definition: idiopathic inflammation of the pubic symphysis
  • Etiology: most likely due to overuse of hip adductors (esp. in athletes) ; following childbirth or pelvic surgery
  • Clinical features
    • Pain in the groin/lower abdomen, which worsens on activity
    • Tenderness on palpating the pubic symphysis
    • The presence of fever suggests other diagnoses (e.g., osteomyelitis of the pubic bone, prostatitis, pelvic inflammatory disease).

• Clinical diagnosis: further workup rarely needed
• Imaging
  • X-ray
    • Usually normal
    • Possible detection of fractures or periostitis at the site of tendon insertion
  • Ultrasound
    • Tendon thickening ^[8]
    • Hypoechoic areas within the tendon
  • MRI
    • Increased signal in abnormal tendons
    • Simultaneous assessment of bone, cartilage, and ligaments ^[9]
• Complete blood count: to rule out infection in patients with osteitis pubis

• Conservative treatment ^[4]
  • Rest
  • Cooling/ice for the first 24–48 hours
  • Topical/oral NSAIDs
  • Physiotherapy: stretching and strength training once the pain has subsided
  • Orthotic braces and bands
• Corticosteroid and lidocaine injections
  • Only considered if conservative treatment has failed
  • Short-term relief (no long-term benefit) ^[10]
  • Injection into surrounding tissue, not directly into tendons
• Surgery ^[4]
  • Indicated in patients with persistent symptoms after 6 months of conservative treatment
  • Excision of abnormal tendon tissue
  • Longitudinal incisions (tenotomies) to release scarred and fibrotic areas

Corticosteroid injections are generally avoided in insertional tendinopathy since they may cause tendon rupture!