Tendinopathy, Tendon pain, Tendon inflammation, Tendinitis, Tendinosis, Tenosynovitis, Pain, Load pain, Decreased load tolerance, Aging, Degeneration, Athlete's pain
Tendinopathy refers to tendon pain and indicates a dysfunction of the tendon, which impairs its ability to transmit force from muscle to bone. The tendon’s recovery is inadequate, leading to disorganized growth of tenocytes (tendon cells), internal cellular abnormalities, disruption of collagen fibers and an increase in non-collagenous material within the tendon.
The term tendinopathy encompasses a variety of clinical conditions related to tendon overuse, decreased load tolerance, pain, and reduced functional capacity.
Despite recent advancements in tendinopathy research, rehabilitation for this condition remains relatively underdeveloped. Our understanding and treatment methods for tendinopathy have significantly changed over the past decade and it is expected that treatments will continue to evolve in the future.
Although we have considerable knowledge about the causes of tendon pain and its rehabilitation, the number of high-quality clinical studies demonstrating positive treatment outcomes is surprisingly low.
Most Common Painful Tendons
Tendinopathy can occur in any tendon, depending on the load applied to it. However, the most typical tendon-related pain conditions are:
Patellar tendon pain
Tennis elbow
Golfer's elbow
Etiology
The rate of re-formation of tendinopathic tendons is increased, making them fragile and more susceptible to damage. It was previously thought that tendons became inflamed when painful, but histological studies have revealed minimal or completely absent inflammation in patients with diagnosed tendon pain. Instead, painful tendons often show disorganized collagen fiber structure and excess tenocyte population. Chronic overuse is typically associated with failed recovery from loading, but similar changes can occur in tendons that are not subjected to load. For this reason, tendon disorders can arise from both overloading and underloading, and the underlying cause is not always a sports performance; even minor exposure to repetitive movements can predispose individuals to the onset of tendon pain.
Tendinopathy can occur in any age group regardless of activity level, but certain groups may be more susceptible. Repetitive loading, such as running, golf or tennis, increases the risk of tendon pain, but factors like obesity, diabetes or a sedentary lifestyle can also contribute to the likelihood of developing tendon pain.
In addition to mechanical factors, there are several other influences that can significantly affect tendon health and pain perception. Understanding these factors provides a more comprehensive view of the etiology of tendon pain:
Genetic predisposition: Certain individuals may have genetic factors that increase their susceptibility to tendon conditions, affecting tendon structure and healing.
Hormonal factors: Hormonal changes, especially in women during menopause, can influence tendon health and contribute to pain.
Inflammatory conditions: Systemic inflammatory conditions, such as rheumatoid arthritis or other autoimmune disorders, can impact tendon health and lead to pain.
Occupational hazards: Repetitive motions or prolonged static positions in certain occupations can lead to tendon pain, affecting a broader audience.
Nutritional factors: Nutritional deficiencies, particularly a lack of vitamins and minerals that support tendon health (like Vitamin C, Vitamin D, and collagen), can hinder recovery and contribute to tendon pain.
Psychosocial factors: Stress, anxiety, or depression can influence pain perception and recovery rates in individuals with tendon issues, highlighting the significant interplay between psychological well-being and physical health.
In summary, the etiology of tendon pain is multifaceted, involving a complex interaction of mechanical, biological, and psychosocial factors that can contribute to the development and persistence of symptoms.
Anatomy and Function of Tendons
The primary function of a tendon is to transmit forces from muscles to bones and to absorb external forces to prevent injury to the muscles. Since a tendon transitions from flexible tissue (muscle) to stiffer and harder tissue (bone), this task can be challenging. Consequently, the load can concentrate at the interface between the tissues, specifically at the tendon’s attachment point to the bone, which is a common site of injury.
The structure of a tendon is not uniform; it can be stiffer in some areas and more flexible in others. This adaptation helps to reduce the concentration of load and the risk of injury. The size and strength of tendons vary depending on how much they are loaded. Just as muscles can be strengthened, tendons can also increase their tensile strength and endurance through specific types of training.
A healthy tendon is white in colour and is primarily composed of tendon cells known as tenocytes (90-95% of the cellular components) as well as early tendon cells called tenoblasts. Tenocytes are responsible for the production of collagen in the tendon, while tenoblasts are developing tendon cells that eventually mature into new tenocytes. The remaining 5-10% of the tendon’s cellular components consist of chondrocytes at the attachment sites, synovial cells and blood cells. Tendinopathic tendons may also contain other cells, such as inflammatory cells, macrophages and myofibroblasts.
Additionally, tendons consist of extracellular matrix, which provides structural support and participates in force transmission. The tendon cells at the attachment sites form collagen that is composed of soluble tropocollagen molecules. These cells bind together to create cross-links, forming insoluble collagen molecules. The structural integrity of the tendon is based on the formation of this collagen structure, which also prevents the propagation of small injuries throughout the tendon.
Tendons also contain a small amount of proteoglycans, which bind water. The water content of a tendon is typically around 55-70%, with most of it bound to the proteoglycans within the tendon. The structure and various factors of the tendon ensure the necessary tensile strength, provide structural support and participate in force transmission in the muscle-tendon unit.
An evolving tendon is well vascularized and metabolically active, but as it matures, its vascularization diminishes, making its nutrient supply reliant on both blood flow and diffusion. Nerve branches that innervate the tendon pass through the surrounding connective tissue structure and the epitenon to reach the surface and inner portions of the tendon. The tendon innervation is primarily afferent, meaning it transmits information from the tissue to the nervous system, primarily responding to stretch, pressure and pain.
The oxygen consumption of tendons is significantly lower than that of muscles, which allows for prolonged loading without fatigue. However, this low metabolic rate also slows down recovery after injury. Understanding the anatomy and physiology of tendons is crucial for the treatment and rehabilitation of tendinopathy, as it helps to assess tendon function and its ability to respond to loading.
Symptoms
The most typical symptom of tendinopathy is pain felt in the tendon, which worsens during loading of the tendon or with stretching or pressure applied to it. In the initial phase, the pain is often intense and sharp, preventing loading of the tendon and surrounding muscles. Over time, the pain becomes dull or aching and this discomfort may persist. At this stage, the most severe pain may only be felt after the activity has ceased or for example, during the following night. It is often thought that if the pain is no longer felt during activity, the tendon issue has resolved. This misconception can lead to a recurrence or prolongation of tendinopathy. A mere reduction in pain does not necessarily indicate complete healing of the tendon.
The tendon area may be swollen, tender to touch and the skin temperature around the tendon region may be elevated. The painful tendon often feels stiff in the mornings and the function of the muscle attached to the tendon is often impaired.
As pain progresses, patients may encounter difficulties in normal daily activities and the intensity of pain can vary depending on the activity. Prolonged tendinopathy often leads to symptoms even at rest or during the night, disrupting sleep. For this reason, it is important to address any arising tendon issues as early as possible, as this allows for quicker and more effective treatment.
Diagnosis
A thorough investigation of the underlying factors and a well-conducted clinical examination are often sufficient for diagnosing tendinopathy. Tenderness of the tendon, possible changes in temperature, swelling and weakness in the function of the tendon and its associated muscle are typically clear indicators of tendinopathy, so more precise tests may not be necessary. In unclear cases or to confirm the diagnosis, ultrasound or MRI may be ordered, where tendon issues can be clearly visualized. Imaging studies can also help exclude other possible causes.
Treatment
The main goal of treatment is to enhance the tendon and muscles ability to withstand loads without unnecessary pain. This objective is important to keep in mind when planning and selecting a treatment strategy from various options. Underlying factors such as age, exercise habits and individual goals must be considered when choosing a treatment intervention.
Corticosteroid and anesthetic injections may provide temporary relief from symptoms, but they can also stress the cross-links of collagen fibers, weakening the tendon’s structure and tensile strength. However, there are situations where tendon pain needs to be relieved quickly, even if only for a brief period, in which case corticosteroid and anesthetic injections may be considered. This is particularly true for athletes experiencing pain during the competition season or during tournaments, where such interventions may be undertaken.
Corticosteroids can also be tried in the treatment of chronic tendon pain when desired results have not been achieved through other means. In the best-case scenario, corticosteroids can break the cycle of tendon pain and inflammation, allowing for the resumption of rehabilitation and strengthening of the tendon.
The effectiveness of surgical treatments is somewhat questionable according to studies and is often comparable to conservative treatment. Surgery is recommended for patients who have experienced long-term pain and diminished function and who have not improved despite treatment. The most common tendon surgeries include procedures on the Achilles tendon, patellar tendon or rotator cuff tendons. Surgical options may include debridement of a degenerated tendon or scar tissue, repair of a partially or completely torn tendon or rerouting a healthy tendon to replace the function of a damaged or painful tendon. Regardless of the surgical method chosen, it is important to remember that postoperative rehabilitation is essential for achieving good surgical outcomes.
Physiotherapy
The content of conservative treatment and physiotherapy is always tailored to the individual patient based on factors that emerge during the interview, clinical examination, and the patient's goals. However, it can be broadly stated that this includes the following elements:
Education and counseling: To enhance the patient's understanding of the nature of the condition, contributing factors, treatment actions, and prognosis.
Manual soft tissue or joint treatment: To improve any range of motion restrictions or to reduce increased tensile load and impaired fluid and blood circulation caused by tense muscles.
Strengthening exercises: To improve the tendon’s load tolerance, tensile strength and overall strength.
Creating a rehabilitation plan aimed at addressing tendon issues requires careful examination and clinical reasoning that takes the patient as a whole into account. It is essential to understand that the tendon and muscle work together as a unit within a larger kinetic chain, influenced by forces that may originate far from the painful tendon itself.
Rehabilitation for tendinopathy varies significantly based on the location of the tendon pain, the stage of tendinopathy, factors identified in the clinical examination, the individual’s activity level, the factors affecting the entire chain and the presence of other simultaneous conditions. That said, below is a four-phase rehabilitation plan whose fundamental principles can be applied to any tendon that is experiencing pain. The specific movements will, of course, vary depending on the tendon, but the principles remain the same.
Phase 1: Pain Relief
The goal of the first phase is to alleviate pain felt in the tendon, whether it involves an acutely injured tendon or a flare-up of a chronically painful tendon. Pain relief is achieved by modifying the load applied to the tendon by avoiding or reducing movements that cause compression or friction of the tendon. Movements that stretch the tendon or leave it compressed can further irritate the tendon. Additionally, it is important to avoid movements where the muscle-tendon unit operates like a spring, meaning it transitions directly from a stretched state to a shortened state. This cycle of stretching and shortening is an important, energy-saving mechanism in the muscle-tendon unit, but for an injured tendon, such loading can be too strenuous.
Instead, the tendon should be loaded isometrically, which means applying resistance while keeping it stationary. This approach not only reduces pain but also improves the function of the injured muscle-tendon unit and promotes fluid and blood circulation to the area. Exercises can reduce pain by activating the so-called descending pain pathways, resulting in a decrease or alteration of the pain signal as it travels upward toward the brain.
Although the use of nonsteroidal anti-inflammatory drugs (NSAIDs) for tendon pain management has been questioned, you may consider short-term use if you feel you cannot cope without medication. A common combination used is paracetamol and ibuprofen. However, NSAID use should not be the sole treatment method, nor do they resolve the underlying causes of tendon pain. Pain and inflammation may also be managed with cold therapy if necessary. You can apply a cold pack to the painful area for 10-15 minutes and repeat the cold treatment every couple of hours if possible. Cold therapy can be continued for 4-7 days, after which its effectiveness significantly diminishes.
Isometric exercises can be performed by contracting the painful muscle-tendon unit for 30-60 seconds, followed by a break of 2-3 minutes. After the rest period, the next repetition is performed, with a total of 3-5 repetitions. This type of exercise should be repeated 3-5 times a day. The exercise does not need to be pain-free, but performing it against severe pain is not advisable. If we consider pain severity on a scale from 0 to 10, where the worst possible pain is ten and the absence of pain is zero, the pain during exercise should not exceed 5/10. Another rule of thumb related to exercise or additional loading of the tendon pertains to the duration of pain; any increased pain resulting from the exercise should not persist for more than a day after stopping the exercise.
Remember that the first phase of rehabilitation focuses on effective pain management and the gradual restoration of tendon loading, which is crucial for the success of the rehabilitation process.
Phase 2: Strengthening
Once the pain has diminished, the focus can shift to the second phase, which aims to increase strength and load tolerance. Strengthening the muscle-tendon unit enhances its ability to manage and transmit loads. Both the tendon and muscle respond to all kinds of loading, but repetitive light loading, such as walking or jogging, is insufficient to stimulate significant adaptations in the muscle-tendon unit. Substantially heavier loads are required for this.
Tendons typically benefit from exercises performed slowly against heavy resistance. While there has been an emphasis on the importance of eccentric, or lengthening, muscle work, current research indicates that the muscle-tendon unit should also be loaded concentrically, which involves shortening the muscle. Therefore, exercises referred to as Heavy Slow Resistance (HSR) training should be selected, where movements are performed slowly against heavy resistance.
In HSR training, heavy loads (approximately 70-85% of 1RM) are used, and the movement is executed slowly. Initially, exercises should be performed in the midrange of the muscle-tendon unit and gradually progress towards larger movements as tolerance increases. Choose a resistance that you can lift with good control for 6-12 repetitions, and perform each repetition slowly, taking about 4-6 seconds per repetition. Complete a total of 2-4 sets, allowing a few minutes of rest between sets. Start with longer sets and gradually move to shorter sets against heavier resistance. Repeat the training 2-3 times a week to ensure adequate recovery.
This phase is crucial because restoring strength is essential for the long-term health of the tendon. The duration of the exercises and the tendon’s response to increased loading must be considered and the rehabilitation program should be adjusted as needed if pain or other functional impairments arise.
In the strengthening phase, exercises aimed at improving control, balance and plyometric (explosive) muscle work can also be added, provided these do not exacerbate pain or functional limitations in the tendon.
Phase 3: Functional Rehabilitation
Rehabilitation for tendinopathy often only requires well-executed phases 1 and 2, especially when combined with ongoing strength training to maintain the tendon’s load tolerance.
However, in cases of more severe or long-standing tendinopathy or when the played sport demands high loads, it is advisable to gradually progress to functional rehabilitation.
Before starting functional rehabilitation, pain must be well managed, and baseline strength should be adequate. As rough guidelines, the following criteria can be considered before transitioning to functional rehabilitation:
Submaximal strength (10RM): Should be symmetrical on both the left and right sides.
Pain related to loading: There should be no pain felt in the tendon during or after movement.
Range of motion restrictions: There should be no restrictions in the surrounding joints.
When planning for functional rehabilitation, it is important to understand what activities the patient is aiming for and to tailor the training accordingly. Functional rehabilitation can be divided into three categories:
Exercises that prepare the painful muscle-tendon unit for upcoming sport-specific loading.
Exercises aimed at improving the load tolerance of the entire kinetic chain.
Correcting factors that predispose to tendinopathy through training and possible passive treatments.
It is essential to assess the patient's movement and look for differences between the symptomatic and asymptomatic sides. Precise assessment helps create a program that can restore the necessary force production, mobility and control for daily life and the playing field. Overall, functional rehabilitation is a complex process that requires expertise and individualized assessment.
Phase 4: Return to Sport
The final phase involves training aimed at facilitating a return to one’s sport without the recurrence of tendon issues. Returning to sport often requires the following types of exercises and interventions:
Increasing force production: Strength training continues by reducing the number of repetitions while increasing the load. The intensity of the exercises increases, allowing the muscle-tendon unit to adapt to faster load transfer and sport-specific demands.
Acclimatization to the cycle of tendon stretching and shortening: Plyometric training continues and becomes progressively more challenging and intense. Exercises are selected based on the sport practiced, the affected area and the individual's level.
Increasing load tolerance: Enhance the tendon’s ability to store energy by gradually increasing the load applied to the tendon during exercises.
Sport-specific training: Incorporate sport-specific training aimed at developing the necessary attributes for the sport without focusing entirely on the sport itself.
Neuroplastic rehabilitation of the tendon: Neuroplasticity refers to the brain's ability to change and adapt based on new experiences. In neuroplastic rehabilitation, the brain is essentially trained to react in new ways. For example, exercises can combine strength and movement training with external cues. Externally guided training, such as executing commands given through auditory or visual prompts, may improve tendon pain, muscle movement and create new neural connections.
Competition: Returning to competitive situations can be considered after full participation in training without any pain in the tendon area.
Self-Care
Rest and modify load: Allow the tendon sufficient rest and avoid activities that worsen pain. Mild or moderate pain that eases shortly after stopping activity is acceptable. However, working against severe or prolonged pain is not advisable.
Isometric exercises: Perform isometric exercises for the painful muscle-tendon unit while keeping resistance stationary. This helps relieve pain and improve muscle function.
Strengthen muscles: Engage in strengthening exercises that target the muscles associated with the tendon. The intensity of the exercises should be gradually increased to enhance the tendon’s load tolerance.
Stretching and mobility exercises: Gradually acclimatize to gentle stretching and mobility exercises that do not cause pain. However, avoid vigorous or prolonged stretching.
Try cold therapy: Cold therapy can help alleviate pain and reduce potential inflammation. Use a cold pack for 15-20 minutes three to four times a day to ease pain.
Take breaks: Remember to take regular breaks during activities that may stress the tendons. Breaks help restore muscle function and reduce ongoing tension.
Pain medication: Ibuprofen or paracetamol can help relieve pain and inflammation, but their use should not be unnecessarily prolonged.
If pain persists or worsens, it is important to consult a healthcare professional experienced in rehabilitating tendon issues.
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