Tendon Injury

Aka: Tendon Injury, Tendon Strain, Tendinopathy, Tendonitis, Tendinitis, Tendinosus, Tendinosis, Muscle Strain

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II. Anatomy: Normal Tendon

  1. Tendons
    1. Tightly packed CollagenCollagen fibers produced by tenocytes and tenoblasts
    2. High strength, flexibility and elasticity that can withstand prolonged and repeated load bearing
    3. Tendons have decreased oxygen demand, and heal more slowly than other soft tissue
  2. Collagen fibers
    1. Collagen fibrils organized into budles of fibers
      1. Each bundle organized into larger bundles
    2. Interwoven with other tendon components
      1. Proteoglycans
      2. Elastin
      3. Lipids
  3. Tendon sheath (epitenon)
    1. Contains nerves and vessels supplying tendon
  4. Osteotendinous Junction (Tendon attachment to bone)
    1. Muscle force is transmitted to this site
    2. Site of most Tendon Injury
    3. Tendons are most hypovascular at this site
      1. Osteotendinous junction most prone to Hypoxia
      2. Appears to be important in Tendinopathy development

III. Types: Tendinopathy

  1. Tendinopathy
    1. Tendon Injury with secondary degeneration and decreased healing WITHOUT significant inflammation
    2. Associated with tendon pain and tendon thickening
  2. Tendonitis (Misnomer; Tendinosus or Tendinopathy are typically the more accurate term)
    1. Acute inflammatory Tendinopathy
      1. Implies tendon inflammation, whereas most Tendinopathy chronic injury is degenerative
    2. True Tendonitis at presentation is uncommon
      1. Sudden onset, resolves completely in days to weeks
      2. Most tendon injuries at presentation are chronic
  3. Tendinosus (histologic term)
    1. Describes most chronic tendon overuse injuries
    2. Chronic course over 3-6 months
      1. Incomplete resolution in up to 20%
    3. Associated with chronic degenerative changes
      1. Collagen degenerates into disordered structure
      2. Proteoglycan ground substance increases
      3. Neovascularization
    4. Key related points
      1. NSAIDs do not help and in fact delay healing (non-inflammatory condition)
      2. Absolute rest delays healing (tendons heal best when under some level of tension)

IV. Risk Factors

  1. Intrinsic Factors
    1. Aging
      1. Tendons become stiff, with decreased perfusion, decreased healing and increased degeneration
    2. Anatomic Factors
      1. Muscle Weakness
      2. Inflexibility
      3. Malalignment
      4. Imbalance
    3. Systemic Factors
      1. Tobacco Abuse
      2. Obesity
      3. Diabetes Mellitus
      4. Rheumatologic Disorders (e.g. Gout, Collagen Vascular Disease)
  2. Extrinsic Factors
    1. Corticosteroids
    2. Overuse or misuse of tools, Exercise equipment (often with improper technique)
    3. Lack of protective equipment

V. Causes: Specific Tendinopathies

  1. See Apophyseal Injury (children)
  2. Arm Tendinopathy
    1. Rotator Cuff Tendinopathy
    2. Biceps Tendinopathy
    3. Triceps Tendinopathy
    4. Lateral Epicondylosis (Tennis Elbow)
    5. Medial Epicondylosis (Golfer's Elbow)
  3. Leg Tendinopathy
    1. Greater Trochanteric Pain Syndrome
    2. Hamstring Tendinopathy (Hamstring Strain)
    3. Adductor Strain (Groin Pull)
    4. Patellar Tendinopathy
    5. Peroneal Tendinopathy
    6. Achilles Tendinopathy
    7. Anterior Tibial Tendinopathy
    8. Posterior Tibial Tendinopathy

VI. History

  1. New or changed activity (esp. repetitive) preceding injury?
  2. Work related injury?
  3. Pain and swelling location, timing and palliative and provocative measures

VII. Exam

  1. See specific examinations for involved region
  2. Symmetric or asymmetric findings?
  3. Evaluate for swelling and tenderness over involved tendons
  4. Passive and active range of motion
  5. Motor Strength
  6. Weigh bearing including arch exam (lower extremity Tendinopathy)

VIII. Symptoms

  1. Gradual onset of localized pain at tendon insertion
  2. Associated with new or increased activity
  3. Initially, limited to sharp pain during activity
  4. Later, dull pain may persist even at rest

IX. Imaging

  1. XRay
    1. Imaging is not typically needed in acute Tendinopathy without Trauma or suspicion for Fracture
    2. Consider when evaluating differential diagnosis of pain source, especially with persistent pain >6 weeks
  2. Ultrasound
    1. Most tendons are well visualized on Ultrasound and offer a dynamic, real-time observation
    2. However, Ultrasound is highly operator dependent
    3. See Shoulder Ultrasound
    4. See Elbow Ultrasound
    5. See Wrist Ultrasound
    6. See Hip Ultrasound
    7. See Knee Ultrasound
    8. See Ankle Ultrasound
  3. MRI
    1. Consider in persistent and refractory course in which xray and Ultrasound are non-diagnostic
    2. Consider that even MRI, which is operator independent, is still non-specific (Test Specificity 70%)

X. Management

  1. RICE-M
  2. Local Cold Therapy (Cryotherapy)
  3. Orthotics (e.g. Tennis Elbow counterforce strap)
  4. Stretching and Strengthening Exercises
    1. Start after acute pain has resolved
    2. Eccentric Exercises (loading Muscles/tendons as they are being lengthened) are preferred
  5. Medications to consider at initial onset (acute phase)
    1. Brief NSAID course for 7-14 days (systemic or Topical NSAID)
    2. Local Corticosteroid Injection
      1. May be more effective than NSAIDs in acute pain
      2. Does not change longterm course of Tendinopathy
      3. Risk of delayed healing
      4. Risk of tendon rupture (esp. with repeated injection), but relatively rare complication (<1%)
        1. Coombes (2010) Lancet 376(9754): 1751-67 [PubMed]
  6. Medications to consider for persistent and refractory Tendinopathy
    1. Topical Nitroglycerin
      1. Usage
        1. May reduce pain with activity and improve strength
        2. Apply one quarter of a 5 mg Nitroglycerin Patch daily to affected area
        3. Requires a Nitroglycerin-free period of 12 hours per day
        4. Systemic Nitroglycerin adverse effects may occur (e.g. Headache)
      2. Efficacy: Mixed Results
        1. Some studies have shown improved pain, strength and patient satisfaction
          1. Gambito (2010) Arch Phys Med Rehabil 91(8): 1291-305 [PubMed]
        2. Other studies show not significantly better than Placebo in acute or chronic Tendinopathy
          1. Loescher (2022) Am Fam Physician 105(2): 196-7 [PubMed]
  7. Sports medicine techniques (consider if lack of improvement in 8 to 12 weeks with other measures)
    1. Tendon fenestration
      1. Rapidly move needle through area of injured tendon resulting in micro-Trauma
      2. Results in local bleeding and regenerative factor infiltration into the area
      3. May be performed with or without Corticosteroid Injection
    2. Dry needling
      1. Thin needle placed within thickened or painful area of Muscle or tendon
      2. May be performed with electrical stimulation
    3. Platelet-rich plasma injections
      1. Growth factors released from Platelets aid tissue rapair and regeneration
      2. Should be combined with a physical therapy directed program
  8. Physical Therapy modalities
    1. Local Therapeutic Ultrasound
    2. Iontophoresis and Phonophoresis
    3. Extracorporeal Shock Wave Therapy (ESWT)

XI. Prevention

  1. Prevent overuse injury
    1. See Athletic Injury
    2. See Occupational Injury
  2. Lower Extremiy Tendinopathy
    1. Ensure Proper Shoe Fit (or Running Shoe)
    2. Avoid provocative factors (e.g. high heals)
  3. Upper Extremity Tendinopathy
    1. See Overuse Syndromes of the Hand and Wrist

XII. Prognosis

  1. Refractory course to 3-6 months of conservative management in 10-45% of Tendinopathy patients

XIII. References

  1. Deu (2022) Am Fam Physician 105(5): 479-86 [PubMed]
  2. Kane (2019) Am Fam Physician 100(3): 147-57 [PubMed]
  3. Khan (2003) Clin Sports Med 22:711-25 [PubMed]
  4. Wilson (2005) Am Fam Physician 72(5):811-8 [PubMed]

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