Continuation of My Elbow Pain Discussion
October 12th 2007 14:42
To further emphasize the greater vulnerability to injury of the wrist extensors over the flexors, Matthijs and colleagues mention how these muscles become fatigued easily. They state that the extensors’ endurance limit is only 15 % of maximal strength discussed above. If grasping or any repeated wrist activities demand the extensors to provide greater than 15 % of their maximum strength, the extensors would need to work aerobically to sustain their functions. But the aerobic work will not last that long.
In wrist motions that require repeated and/ or sustained forearm muscle activation-for example power grasping- the type of contraction that mainly occurs is isometric contraction (with respect to power grasping, as the fingers flex for grip closure the extensors initially carry out short eccentric contraction before contracting isometrically for the rest of the phase). And as more strength is required, greater isometric contraction should be generated by the extensors (greater than 15 % of maximum strength). However there is a price to pay. Isometric contraction increases pressure within the muscles, impeding capillaries that provide oxygen for the muscles to work aerobically. Consequently vascularization to the area becomes insufficient. The extensors then can become ischemic making them more prone to injury.
One of the weakest points of the wrist extensors is their tendon attached to the lateral epicondyle. This is more pronounced especially during quick and strong wrist extension. Unlike the muscle bellies their tendons are unable to quickly adapt to an increase in tensile strength. These tendons do not have enough time to adapt to certain increased loads. In addition to that they have much slower acting nutritive process in regeneration and reparation. And so frequent repeated tensile stresses can quickly translate to overuse. Consequently, pain is superimposed initially over the lateral epicondyle, marking tendon affection even before muscular injury happens.
Going back to the issue about presence of inflammation over tendons and bellies, are there other evidences that could attest that inflammation does not occur all the time? Aside from what has been stated above, Ljung et al (1999) feature in their review of literature that “the aetiology of lateral epicondylitis (tennis elbow) is poorly understood”. They add that, “previous histopathological studies have mainly focused on the origin of ECRB muscle”. However they mention that these studies provided conflicting results. Other researchers like Goldie attribute pain to inflammation and granulation tissue but no microruptures. Others like Coonrad, Hoopert, and Cyriax attribute pain to microruptures in the proximal tendon. And still others like Regan mentions that no inflammation occurs and instead there is a presence of degenerative changes. From these statements we can conclude that traumatic and/ or degenerative type of lateral epicondylalgia presents itself differently to different types of patients.
Ljung and colleagues also point out that the wrist extensors injury can also be attributable to the type of contraction these muscles perform. We mentioned earlier that isometric contraction can harm the wrist extensors. But the above researchers believe that even eccentric contraction can impose structural damage to the muscles especially at its myofibrillar apparatus. “The high tension levels of eccentric contractions may cause muscle damage, fiber necrosis, and regeneration”, they state.
If we are to go back to the discussions by Matthijs et al, the same point is raised, but this time giving emphasis on the tendons. According to them the ability of the tendons to withstand tensile stress is superior only during dynamic positive activity (isotonic contraction) but not when the muscles and an external force produce dynamic negative activity (eccentric contraction).
Faulty Biomechanics of the Cervical Region
The cervical spine is another major source of elbow pain with cervical radiculopathy being the primary etiology (Resari and Gilliam, 20005). Radiculopathy is any condition that affects the spinal nerve roots. This presents as pain (dermatomal affectation) or numbness in the distribution of the specific nerve root affected. Possibly sensory alteration over the nerve’s area of distribution can be coupled with weakness of the muscles controlled by that same nerve root (myotomal affectation). The most common causes of cervical radiculopathy are disc herniation and degeneration, spur formation, and hypermobility state.
If we are to expect neurologic pain over the lateral epicondyle, most probably the C5-C6 nerve roots are affected. This time we can also expect weakness of the elbow flexors and/ or wrist extensors (Magee, 1997).
Aside from what was mentioned above, what other adverse effect can result from nerve compressions? According to Meadows (2006), spinal nerve root compression can lead to a reduced axoplasmic flow with consequent trophic malnutrition and weakening of the collagen in the tendons and muscles they innervate. The result of this is vulnerability to damage.
What actually happens within the cervical spine that can cause nerve impingement or radiculopathy? In disc herniation the nucleus of the intervertebral disc protrudes backward and laterally. Though it is more likely to occur in the lumbar area than in the cervical region, we cannot remove the fact that protrusion can still happen anywhere within the mobile segments of the spine. The contributory factors to this condition maybe aging and degeneration (Cailliet, 1991). What would be the most likely motion that can direct an anteriorly located nucleus towards the posterior? Obviously neck flexion involving weak and degenerating intervertebral disc can displace the nucleus posteriorly. Afterwards the space-occupying protruded disc can impinge the nerve roots, thus causing radiculopathy.
TO BE CONTINUED...
UP NEXT: HOW TO MANAGE Lateral Epicondylalgia?
In wrist motions that require repeated and/ or sustained forearm muscle activation-for example power grasping- the type of contraction that mainly occurs is isometric contraction (with respect to power grasping, as the fingers flex for grip closure the extensors initially carry out short eccentric contraction before contracting isometrically for the rest of the phase). And as more strength is required, greater isometric contraction should be generated by the extensors (greater than 15 % of maximum strength). However there is a price to pay. Isometric contraction increases pressure within the muscles, impeding capillaries that provide oxygen for the muscles to work aerobically. Consequently vascularization to the area becomes insufficient. The extensors then can become ischemic making them more prone to injury.
One of the weakest points of the wrist extensors is their tendon attached to the lateral epicondyle. This is more pronounced especially during quick and strong wrist extension. Unlike the muscle bellies their tendons are unable to quickly adapt to an increase in tensile strength. These tendons do not have enough time to adapt to certain increased loads. In addition to that they have much slower acting nutritive process in regeneration and reparation. And so frequent repeated tensile stresses can quickly translate to overuse. Consequently, pain is superimposed initially over the lateral epicondyle, marking tendon affection even before muscular injury happens.
Going back to the issue about presence of inflammation over tendons and bellies, are there other evidences that could attest that inflammation does not occur all the time? Aside from what has been stated above, Ljung et al (1999) feature in their review of literature that “the aetiology of lateral epicondylitis (tennis elbow) is poorly understood”. They add that, “previous histopathological studies have mainly focused on the origin of ECRB muscle”. However they mention that these studies provided conflicting results. Other researchers like Goldie attribute pain to inflammation and granulation tissue but no microruptures. Others like Coonrad, Hoopert, and Cyriax attribute pain to microruptures in the proximal tendon. And still others like Regan mentions that no inflammation occurs and instead there is a presence of degenerative changes. From these statements we can conclude that traumatic and/ or degenerative type of lateral epicondylalgia presents itself differently to different types of patients.
Ljung and colleagues also point out that the wrist extensors injury can also be attributable to the type of contraction these muscles perform. We mentioned earlier that isometric contraction can harm the wrist extensors. But the above researchers believe that even eccentric contraction can impose structural damage to the muscles especially at its myofibrillar apparatus. “The high tension levels of eccentric contractions may cause muscle damage, fiber necrosis, and regeneration”, they state.
If we are to go back to the discussions by Matthijs et al, the same point is raised, but this time giving emphasis on the tendons. According to them the ability of the tendons to withstand tensile stress is superior only during dynamic positive activity (isotonic contraction) but not when the muscles and an external force produce dynamic negative activity (eccentric contraction).
Faulty Biomechanics of the Cervical Region
The cervical spine is another major source of elbow pain with cervical radiculopathy being the primary etiology (Resari and Gilliam, 20005). Radiculopathy is any condition that affects the spinal nerve roots. This presents as pain (dermatomal affectation) or numbness in the distribution of the specific nerve root affected. Possibly sensory alteration over the nerve’s area of distribution can be coupled with weakness of the muscles controlled by that same nerve root (myotomal affectation). The most common causes of cervical radiculopathy are disc herniation and degeneration, spur formation, and hypermobility state.
If we are to expect neurologic pain over the lateral epicondyle, most probably the C5-C6 nerve roots are affected. This time we can also expect weakness of the elbow flexors and/ or wrist extensors (Magee, 1997).
Aside from what was mentioned above, what other adverse effect can result from nerve compressions? According to Meadows (2006), spinal nerve root compression can lead to a reduced axoplasmic flow with consequent trophic malnutrition and weakening of the collagen in the tendons and muscles they innervate. The result of this is vulnerability to damage.
What actually happens within the cervical spine that can cause nerve impingement or radiculopathy? In disc herniation the nucleus of the intervertebral disc protrudes backward and laterally. Though it is more likely to occur in the lumbar area than in the cervical region, we cannot remove the fact that protrusion can still happen anywhere within the mobile segments of the spine. The contributory factors to this condition maybe aging and degeneration (Cailliet, 1991). What would be the most likely motion that can direct an anteriorly located nucleus towards the posterior? Obviously neck flexion involving weak and degenerating intervertebral disc can displace the nucleus posteriorly. Afterwards the space-occupying protruded disc can impinge the nerve roots, thus causing radiculopathy.
TO BE CONTINUED...
UP NEXT: HOW TO MANAGE Lateral Epicondylalgia?
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