Tendon and Ligaments: Injuries and Healing

Quote: "Open tendon injuries are common in trauma and orthopedic patients and require primary surgical treatment."

Main Document

Tendon - A tendon (or sinew) is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fasciae; all three are made of collagen.

Ligament - In anatomy, a ligament is the fibrous connective tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.

While similar to tendons, ligaments connect bone to bone and help to stabilize joints. Ligaments are composed mostly of long and stringy collagen fibers that create bands of fibrous and tough connective tissue. Ligaments are somewhat elastic and may be stretched or gradually lengthen, increasing a person's flexibility. Yet if ligaments are stretched beyond a certain point they may become overstretched and compromise the integrity of the joint they are supposed to be stabilizing. The term, 'double-jointed,' refers to people who have very elastic ligaments, allowing them to move their joints into extreme positions. Ligaments; especially the, 'anterior cruciate ligament (ACL),' often times are talked about in sports news because they are prone to tearing - something that sidelines football players, skiers, or soccer players for example.

Tendon and Ligament Injury

Tendons and ligaments can both suffer injuries due to a direct blow or from overuse. Ligaments may be overstretched, something referred to as a, 'strain.' A strain can involve just partial tears to a ligament, or even a complete tear. Tendon injuries are called, 'sprains,' and happen when they are stretched too far or overworked. A strain may be either a partial or full tear. Injuries like these are common in sports and require treatment in order to avoid chronic issues. Tendons and ligaments can all be stretched and strengthened to help with avoiding injuries.

Injuries to a person's tendons are the second most common injuries to their hands and are an important subject in trauma and orthopedic patients. Most injuries are, 'open injuries,' to the extensor or flexor tendons, although less frequent injuries such as damage to the functional system tendon sheath and pulley or dull avulsions must also be considered. Following a clinical examination, MRI scan and ultrasound have proven to be important diagnostic tools.

Tendon injuries largely require surgical repair, dull avulsions of the distal phalanges extensor tendon may receive conservative therapy. Injuries of a person's flexor tendon sheath or single pulley injuries are treated conservatively and multiple pulley injuries most likely require surgical repair. In the postoperative course of flexor tendon injuries, the principle of early passive movement is important to trigger an, 'intrinsic,' tendon healing that guarantees a positive outcome. A number of substances have been evaluated to find out if they improve tendon healing, although little evidence has been found. Despite this fact, hyaluronic acid might improve a person's intrinsic tendon healing.

The Hand and Injuries

The hand is the human executing organ and is in the center of daily life activities. The hand is always exposed to overuse and injuries. With the change in society from an industrial one to a service-based society, an assumed decrease in hand injuries has not been found - most likely due to an increase in private activities such as do-it-yourself work and sports.

Based upon a population of injured persons, Angermann and Lohmann showed that 28.6% of people treated in emergency care involved hand injuries. On average, hand injuries count for 14% to 30% of all people treated in emergency care in the Danish population. Tendon lesions are in second place at 29%, while fractures are in first place at 42%. Skin lesions held third place in the study. While only 2% of the people were hospitalized - hand injuries, particularly tendon lesions, played a key role in traumatic and orthopedic treatment. Degenerative lesions were noted as well.

Extensor Tendon Injuries

A person's long fingers hold four common extension tendons namely, 'extensores digitorum communes,' and additionally the extensor indices for the second and fifth finger. The tendon of the extensor digitiminimi runs through the fifth tendon compartment, the rest through the fourth compartment. On the level with the dorsum of the hand and the metacarpophalangeal joints, a number of cross-connections are to be found - the, 'connexi interendinei.'

On level with the proximal interphalangeal joint or, 'PIP,' the extensor tendon separates into two lateral reins and one central rein. Two different extensor tendons reach to a person's thumb, the extensor pollicis longus and the extensor pollicis brevis. All named tendons form the extrinsic system, tendons of a person's muscles that originate proximal to the person's hand itself. The extrinsic system is supported by the intrinsic one.

Open tendon injuries are common in trauma and orthopedic patients and require primary surgical treatment. A differentiation between complete or partial rupture has to be made. A lesion of less than 60% of the tendon's diameter should be treated conservatively. Multiple bio-mechanical in vivo and ex vivo studies have proven that conservatively treated partial tendon ruptures showed a higher tear resistance when compared to the surgically treated ones.

Chronic degenerative tendon ruptures as seen in rheumatic patients must be distinguished from these traumatic ruptures. A combined entity found in highly active people - largely rock climbers, is a chronic tendinosis and degeneration followed by an acute tear. High intensive stress, in combination with chronic tenosynovitis and tendinosis, may lead to a rupture of a person's tendon - even though only minor stress has been experienced. In addition to a poor blood supply to the tendon, micro-trauma and microscopic structural damage may lead to a modest prognosis for the person.

Healing Tendons

From a histological perspective, tendons consist of very long and collagenous fibers that are arranged into bundles. Similar to a rope ladder, elastic fibers and vessels are entangled in between these bundles. To provide the needed slippage a, 'peritendeum,' or a tendon sheath covers a person's tendons. Pulleys strengthen these structures along the phalanges. Friction plays an important role in the origin of injuries and chronic inflammatory diseases of the tendons, their sheaths and pulleys.

After sustaining an injury, the healing process emerges from the peritendeum and peritendinous tissue. Due to this fact, a distinction of an extrinsic to an intrinsic healing process must be made. Characteristic for an extrinsic healing process is a distinctive inflammatory response followed by proliferation and remodeling.

Fibroblasts of the paratenon have an important role in migration, which leads to adhesions. Immobilization supports the adhesion process. The intrinsic healing process, supported by movement of the person's tendon, is characterized by immigration of, 'fibroblast-like tenocytes,' which produce the collagenous tissue and carry out the remodeling process.

If the person's inflammatory response is minimal, their clinical outcome is better. The ratio of early passive movement therapy leads to better nutrition and strength of the person's tendon. Factors such as age, scar formation disposition, motivation, overall health and injury risk, injury type, synovial containment and surgical technique are all relevant. Three phases of tendon healing have been defined. A migration of peripheral cells and invasion of blood vessels happens. The person's tendon and surrounding tissue heals. Remodeling occurs in the third phase of healing due to function of the tendon and movement. A person's tendon regains its daily life loading capacity after twelve weeks of healing and the injured person may pursue activities such as sports after four months. The remodeling process may last up to a year.

Tendon injuries of the hand
www.ncbi.nlm.nih.gov/pmc/articles/PMC3377907/

Ligament/Tendon Structure-Function
www.umich.edu/~bme332/ch10ligten/bme332ligamenttendon.htm

Differences Between Ligaments & Tendons
www.livestrong.com/article/217679-differences-between-ligaments-tendons/

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