Tendon injuries can be acute (sudden) or chronic (longstanding), and caused by intrinsic or extrinsic factors, either alone or in combination. Tendinopathy is a common cause of disability and accounts for a significant proportion of overuse injuries in sports. Conservative management strategies for tendinopathy is strongly supported in the literature.
What is tendinopathy?
Tendons are the tough fibres that connect muscle to bone. Most tendon injuries occur near joints, such as the shoulder, elbow, knee, and ankle. Tendinopathy is described as an overuse (degenerative) injury to tendons with a lack of inflammatory change in tissue. Symptoms include pain, redness, tenderness and stiffness (particularly in the morning) about the affected tendon and crepitus (crunching or clicking sounds made when the tendon is stretched or compressed).
What causes tendinopathy?
Tendinopathy is one of the most frequent overuse injuries associated with sport. Usually it occurs in major tendons, such as the Achilles, patellar, rotator cuff, and forearm extensor tendons. Overuse or overstrain causes microscopic injury to the tendon, leading to inflammatory changes in the tissue, causing tendonitis. Tendinopathy is essentially a failed healing response after an episode of tendonitis.
Stages and pathophysiology of tendinopathy
Tendons, as with other tissues in the body, undergo stages of tissue healing. The tendon continuum is a proposed new strategy when approaching tendon pain. There are 3 stages to this continuum: reactive tendinopathy, tendon disrepair and degenerative tendinopathy. Tendons can move up and down this continuum and this can be achieved through adding or removing load to the tendon especially in the early stages of a tendinopathy.
The biochemical changes that occur in the tissues during tendinopathy follow these three stages of tendon continuum: reactive, disrepair and degenerative tendinopathy:
- Reactive: There is a random production of abnormal tenocytes (cells found in tendons) and disruption to collagen (connective tissue protein).
- Disrepair: There is then an increase in noncollagenous matrix (space in between cells) in which the body will try to rapidly remodel matrix leading to mechanically less stable tendons that are more susceptible to injury.
- Degenerative: Changes are now irreversible. There would be areas of cell death, trauma and tenocyte exhaustion and general disorganisation of the cell matrix, which is associated with a poorer prognosis (outcome).
There are several risk factors for tendinopathy, some are extrinsic and more easily managed and others are intrinsic:
- Hormone replacement therapy
- Contraceptive medication
- Lack of range of movement
- Strength imbalance
- Poor vascularity
- Altered lower limb biomechanics
Progressive loading strategies
Tendon energy storage refers to load/strain energy that is stored and elastically recovered within a muscle-tendon complex during each contractile cycle of a muscle. In other words, tendons are energy-storing and energy-releasing, elastic/spring-like tissues: they respond to loading strategies. Indeed, the evidence suggests that the best intervention for tendinopathy is a progressive loading (and de-loading) exercise program with a return to usual training or activity as the final end goal.
When deciding which exercise to prescribe, clinicians must identify the stage of tendinopathy in their patient, as this will guide the clinician to which type of exercise most indicated. For instance, in reactive tendinoapthy, there is a great deal of pain and tenderness, as so it would be inappropriate to prescribe heavy-loading exercises. Clinicians use a four-stage program to subgroup patients with tendinopathies:
- Pain relief and isometric exercises. Isometric exercises involve those where the muscle contracts, but the joint angle and muscle length do not change. This type of exercise has shown to reduce the initial pain associated with tendinopathies.
- Isotonic strength endurance where appropriate. Unlike isometric, isotonic exercises involve actually moving the joint and lengthening the muscle: there is an eccentric or lowering phase, and a concentric or lifting phase. Examples include calf raises, squats, stair climbing, bicep curls and push-ups.
- Energy storage exercises. Exercise in this stage places faster loads on the tendon, causing the tendon to store more energy and begin to act like a spring. Examples of exercises in this stage include skipping, hopping, jumping and faster stair climbing.
- Energy storage and release exercises. These exercises are a progression from stage 3, where the speed increases and the release of energy from the tendon occurs. Examples include faster skipping, running drills with directional changes.
Eccentric exercises are those that load tendons and muscles under stretch. For instance, an eccentric exercise for the biceps brachii muscle would be straightening the elbow from a bent position holding a weight. Eccentric exercises have been proposed to promote collagen fibre within the tendon, enhancing the remodelling process. Positive effect in terms of reducing pain and improving function has been reported in both athletic and sedentary patients with no adverse effects. They are perhaps the most commonly prescribed conservative management strategy for tendinopathy and with good reason: there is considerable evidence in the scientific literature to support and justify its use in patients with various tendinopathies.
Shock wave therapy
Extracorporeal shock wave therapy is becoming more widely used to address the failed healing response of a tendon. The shockwave machine sends a high amplitude pulse of mechanical energy, similar to soundwaves, generated by an electromagnetic coil or a spark in water. It works by stimulating soft-tissue healing and inhibits pain receptors through direct and indirect mechanical forces via cavitation (formation of vapour cavities in a liquid, like bubbles, which are the consequence of forces acting upon the liquid).
Low-energy shock wave therapy or eccentric training for the management of Achilles tendinopathy showed comparable results in a randomised controlled trial, and both management modalities produced outcomes superior to those of no intervention. Furthermore, the association of eccentric loading and repetitive low-energy shock wave therapy is more effective than eccentric loading alone.