Tendons: Function, Injury, and Recovery

Tendons are strong connective tissues that link muscle to bone. They play a critical role in movement by transferring forces generated by muscle contractions to bones, allowing for joint motion.

While tendons are not typically part of the joint itself, they play a role in supporting nearby joints. Unfortunately, tendons are also commonly vulnerable to injury, especially through repetitive stress or sudden force.

What Happens When Tendons Are Injured?

Tendons can become inflamed and shortened, causing pain and restricted joint motion. These injuries can result from overuse, improper movement patterns, or the natural aging process.

Dr. Horowitz believes that people should be educated about tendons and how to protect them—because tendon health is often overlooked in preventing injury. You can help reduce the risk of tendon injuries and chronic pain, especially as we age.

Tendons & Aging

As we age, tendons heal more slowly and become more vulnerable to injury. A few key age-related changes include:

  • Reduced healing capacity
  • Increased low-grade inflammation
  • Changes in structure and strength, which can lead to contractures, tears and ruptures
  • Hormonal changes (e.g., decreased estrogen in older women loosens tendon tissue, increasing risk of traumatic injury and inflammation)

Some tendons are particularly affected by aging:

  • Achilles tendon
  • Rotator cuff tendons (especially the supraspinatus) and biceps brachii
  • Patellar tendon (knee)
  • Posterior tibial tendon (lower leg and foot)
  • Flexor hand tendons
  • Extensor foot and shin tendons

Chronic inflammation further delays healing and increases the risk of sudden ruptures or tears.

The longer inflammation persists, the more it delays healing and increases the risk of sudden ruptures or tears.

Types of Tendon Injuries:

The term tendinopathy broadly describes tendon pain and dysfunction. The suffix “-pathy” means disease or disorder.

Types of tendinopathies:

  • Tendinitis: Acute inflammation and swelling of tendon fibers with inflammation and immune cell involvement.
  • Tenosynovitis: Inflammation of paratenon (the sheath surrounding the tendon)
  • Tendinosis: Chronic degeneration of tendon tissue due to repetitive mechanical strain or overuse. Often involves scar tissue and tendon shortening, but with little or no inflammation unless acutely aggravated.

There is currently not a lot of research on Tendinosis. Injured tendon tissues may suffer from a lack of oxygen due to overuse and the presence of lactic acid.

Complications with tendinosis can include the following:

  • Contractures of the tendon
  • Tendon adhesions
  • Atrophy of muscles
  • Loss of functionality

Commonly Injured Tendons

  • Achilles
  • Patellar
  • Hamstring
  • Gluteal
  • Lateral Epicondyle (at the elbow)
  • Tibialis Posterior (posterior shin splints)

Tendons heal slowly. Up to 46% of all musculoskeletal injuries involve tendons.

Approximately 50% of runners experience Achilles tendinopathy before age 45.

Causes of Tendon Tears & Ruptures

  • Sports injuries: 60% of tendon tears occur during recreational or competitive sports; ⅓ happen while playing basketball.
  • Achilles tendon: Most commonly ruptured, accounting for 56% of tendon ruptures.
  • Men: Eight times more likely to experience tendon ruptures than women.
  • Poor healing: Chronic tendinosis or inadequately healed tendinitis increases rupture risk.

How Common Are Tendon Injuries?

  • Achilles: 20% of all tendon injuries; ruptures affect 1% of men aged 30–50
  • 52% of former elite runners
  • 5.9% of sedentary individuals
  • 24% of competitive athletes
  • 18% of athletes under 45

Patellar tendinopathy:

  • 45% of volleyball players
  • 32% of basketball players

Lateral epicondylitis (tennis elbow): 4–7 per 1,000 lifetime prevalence

Rotator cuff pathology:

  • 9.7% of people under 20
  • 50% of 60-year-olds
  • 62% of those 80 and older

How Tendons Heal

Tendons are slow to heal because they have a limited vascular supply.

Tendons heal in three continuous stages:

  1. Inflammation
  2. Proliferation (collagen production)
  3. Remodeling: Includes cell death (apoptosis), disorganized matrix, and neovascularization (growth of new blood vessels and nerves)

With vascular changes, new nerves grow that contribute to pain through a process called neurogenic inflammation. By disrupting the pain signals, pain can be reduced.

What Affects Tendon Healing?

  • Body mass index
  • Genetic predisposition
  • Nutrition
  • Poor body mechanics
  • Muscle imbalances
  • Lack of flexibility
  • Diabetes mellitus (alters collagen structure)
  • Smoking (reduces oxygen to tendons)
  • Dyslipidemia (fat deposits weaken collagen)
  • Corticosteroids (weaken tendon strength)
  • Hemodialysis
  • Renal failure

Treatment for Tendinopathy

Conservative Treatment for Tendinopathy:

  • Rest and modification of activities
  • Manual therapy
  • Ultrasound therapy
  • Massage
  • Stretching and range of motion exercises
  • Physical or occupational therapy
  • Isotonic and eccentric strengthening exercises
  • Icing acute injuries and heat for chronic tendinosis

Avoid:

  • Movements or activities that initially caused the pain
  • Prolonged use of corticosteroids or NSAIDs

Steroid injections used to be a common treatment, but they are no longer first-line due to their association with worse long-term outcomes despite providing short-term pain relief.

Recovery Timeline:

For acute injuries, seek care as soon as possible.

For chronic tendinosis, healing often takes three to six months.

Many overuse injuries recover with proper management, however without proper treatment, areas of scar tissue can remain within a tendon and limit full range of motion of the associated joint.

If left untreated, tendinosis can result in tendon rupture.

Older adults (60+) and those with a history of tendon rupture may have longer recovery timelines.

Prevention

  • Improve physical fitness and flexibility
  • Strengthen supporting muscles
  • Massage and stretch tendons regularly
  • Address biomechanical issues early
  • Avoid overtraining or sudden increases in activity
  • Seek care early
  • temporarily avoid the movement or activity that triggered the condition
  • As recovery progresses, patients should warm up before exercise,
  • limit repetitive movements at work, and
  • avoid prolonged inactivity by staying mobile throughout the day.
  • Strengthening muscles and improving overall physical fitness can also reduce the risk of tendinosis.

For help with a tendon injuries, call My Toronto Chiropractor Health Clinic at (647) 349-4909 or complete the form below to ask Dr. Horowitz a question: