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Musculoskeletal Disorders

Musculoskeletal disorders (MSDs), also called cumulative trauma disorders, are gradual-onset injuries that usually occur after repeated micro-trauma to a specific body part. They may take weeks, months or years to develop and are often ignored at first due to the slow onset of symptoms. MSDs most commonly affect the wrists, shoulders, neck, eyes and back. Specifically, they affect the nerves, tendons and muscles in those areas. MSDs can also affect specific fingers, elbows and the knees, though these are less common.

MSDs are disorders of the muscles, nerves, tendons, ligaments, joints, cartilage and spinal discs. Some examples of MSDs include: Rotator cuff syndrome, De Quervain’s disease, Trigger finger, Tarsal tunnel syndrome, Sciatica, Epicondylitis, and tendonitis.

One way to think about musculoskeletal disorders is to think of parts of your body (wrists, neck, eyes, etc.) as a bucket. Micro-trauma from a variety of activities starts to fill that part of your body’s trauma bucket. At the same time, your body is healing and removing trauma from the bucket. If more trauma goes into the bucket than can be removed by healing, the result can be pain, impaired movement and/or weakness. MSDs occur based upon the duration and severity of exposure to ergo stressors. MSDs and MSD symptoms usually occur gradually over a long period of exposure where brief exposure would not cause harm.
Unfortunately, most of the structures initially affected by MSDs do not have nerve endings to let you track how much micro-trauma your body has left to heal. In a sense, this is good because we are always experiencing some micro-trauma and we would always be in pain. On the other hand, this lack of obvious feedback means we have to pay extra attention to the MSD signs we do get.

Remember, MSDs are gradual-onset disorders, they usually take a while to occur. Therefore, be on the lookout for lingering:

  • Discomfort or Pain: A tendon may not have nerve endings but if it starts to swell, becomes damaged or the muscles around it are being overworked, you may feel some discomfort or pain. If it occurs as soon as you arrive at work or start a task, if it wakes you up at night, follows you home, take notice!
  • Tingling, Numbness or Weakness: Some MSDs affect nerve function. If your hands “fall asleep” unexpectedly or wake you up in the middle of the night with that “pins and needles” feeling, this may be a sign of MSD onset. Likewise, if you experience trouble opening doors, jars, etc., this may be a sign.

Other signs include:

  • Burning
  • Swelling
  • Change in color
  • Tightness, loss of flexibility
If you feel you have an MSD make sure to:

The UNC-Chapel Hill University Employee Occupational Health Clinic (UEOHC) is dedicated to providing University employees with medical care for work-related injuries and illnesses.

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Carpal Tunnel syndrome affects the hands and wrists.

How it Happens

Carpal tunnel syndrome is caused by compression of the median nerve where it passes through the wrist (the carpal tunnel). The carpal tunnel is formed by the radius and ulna (bones of the forearm) towards the back of the hand and the transverse carpal ligament towards the front of the hand. Passing through this tunnel are the tendons that flex the fingers and the median nerve. Bones, ligaments and tendons are very tough and resist compression. Nerves, on the other hand, do not. Repeated irritation can cause the tendons to swell and put pressure on the median nerve. Over time, this can damage the nerve. This disorder can occur as a result of repetitive/forceful motion of the hands and wrists. Bent wrist postures increase the risk associated with this MSD. Carpal tunnel syndrome can occur spontaneously due to fluid retention during pregnancy, other personal factors or can be brought about by activities involving repetitive and/or forceful and/or bent wrist motions such as prolonged typing, knitting, gardening and repeated use of a vibrating hand tool.

Signs and Symptoms

Early signs or symptoms may include tingling or numbness tingling in the thumb, index or middle finger and one half of the ring finger. Tingling often occurs at night and sufferers often complain of being awakened at night by the hand “falling asleep”. Since the nerves control muscle strength and dexterity as well as sensation, an affected hand may become weak and clumsy, causing difficulty opening jars, opening doors or dropping of objects unexpectedly.

For more information, see the US National Library of Medicine: Carpal Tunnel Syndrome.

Cubital tunnel syndrome affects the hands and elbows.

How it Happens

The ulnar nerve runs down the arm and crosses the elbow at the area where the “funny bone” is. The ulnar nerve actually is the funny bone! After crossing the elbow, the ulnar nerve goes down the forearm and into the hand where it provides sensation to the pinkie and half of the ring finger. Trauma to the “funny bone” (bumping it, for example) can damage the nerve. Frequently bending the elbow (such as reaching or lifting) and leaning on the elbow can also cause compression/irritation of the nerve.

Signs and Symptoms

The first signs of cubital tunnel syndrome are numbness in the pinkie and half of the ring finger. Later, this numbness may turn into pain. Since the nerves control muscle strength and dexterity as well as sensation, an affected hand may become weak and clumsy.

For more information, see the American Society for Surgery of the Hand.

De Quervain’s Tenosynovitis affects the thumb side of the wrist and forearm.

How it Happens

De Quervain’s Tenosynovitis is caused by rubbing or swelling of two tendons that pull the thumb back away from the hand. The two tendons run through a tunnel on their way to the thumb. Repeated or sustained grasping, pinching, squeezing or wringing may cause the tendons to become inflamed where they pass through that tunnel. This inflammation makes it difficult for the tendons to pass through the tunnel. Over time, scar tissue may build up causing a permanent condition.

Signs and Symptoms

De Quervain’s Tenosynovitis usually starts as a sore feeling on the thumb side of the wrist and forearm. As it advances, the pain may spread up the forearm or down the wrist and grasping with the thumb becomes more and more painful. Eventually, the tendons may become so inflamed that they actually squeak as they pass through the tunnel.

For more information, see the Mayo Clinic: De Quervain’s Tenosynovitis.

Lateral Epicondylitis (Tennis Elbow) affects the elbows.

How it Happens

The muscles on the back of the forearm, that bend the wrist backwards, run from the wrist to the elbow where they attach to a tendon that continues on to the lateral epicondyle at the elbow. Repeatedly bending the wrist back (as with a tennis backhand), lifting with the elbow straight and twisting the hand palm side up (as with turning a doorknob) require these muscles to activate and pull on the tendon. Overuse of this tendon can cause the tendon to become inflamed or scar.

Signs and Symptoms

Lateral epicondylitis results in pain and tenderness at the outside of the elbow. In advanced cases, this tenderness and pain may spread down the forearm. Pain is usually felt when bending the wrist backwards or holding a heavy object and holding the wrist straight.

For more information, see the US National Library of Medicine: Lateral Epicondylitis.

Low Back Pain, Sciatica, Herniated Spinal Disk affects the low back and legs.

How it Happens

Back disorders can result from a number of factors. Usually, they are attributed to degeneration or injury to the spinal disks. To start with some quick anatomy, the vertebrae of the spine are held apart by spinal disks, which act as shock absorbers for the spine. The disks give mobility to the spine and keep the vertebrae apart so that nerves can pass between vertebrae from within the spinal column (spinal cord) and out to the rest of the body.

Signs and Symptoms

Low back pain usually starts at the lower spine and may spread to the buttocks and thighs. Sciatica is usually experienced as a pain or numbness in one or both legs, often extending below the knee. Since the nerves control muscle strength and dexterity as well as sensation, the affected area may become weak and numb.

For more information, see the US National Library of Medicine: Low Back Pain, Sciatica, Herniated Spinal Disk.

Medial Epicondylitis (Golfer’s Elbow) affects the elbows.

How it Happens

The muscles on the inside of the forearm, that flex the wrist, run from the wrist to the elbow where they attach to a tendon that continues on the medial epicondyle at the elbow. Repeatedly flexing the wrist (as in an overhand swimming stroke), require these muscles to activate and pull on the tendon. Overuse of this tendon can cause the tendon to become inflamed or scar.

Signs and Symptoms

Medial epicondylitis results in pain and tenderness at the inside of the elbow. In advanced cases, this tenderness and pain may spread down the forearm. Pain is usually felt when flexing the wrist forward.

For more information, see the Mayo Clinic: Medial Epicondylitis.

Radial tunnel syndrome affects the forearms.

How it Happens

The radial nerve runs down the arm and passes through a muscle/bone tunnel on the outside of the elbow. During wrist pushing, pulling, bending or twisting of the forearm can cause these muscles to compress, stretch or irritate the radial nerve.

Signs and Symptoms

Similar to lateral epicondylitis, radial tunnel syndrome results in pain and tenderness at the outside of the elbow. However, radial tunnel syndrome pain occurs farther down the elbow than lateral epicondylitis pain.

For more information, see the Cleveland Clinic.

Rotator Cuff Syndrome (Impingement Syndrome) affects the shoulders.

How it Happens

Impingement syndrome is caused by rubbing or pinching the tendons, bursa and muscles in the shoulder. The acromion is a bone at the shoulder end of your collar bone. The acromion curves downward, pointing into the shoulder. Just under the acromion are the tendons, muscles and bursa (a structure that reduces friction in the shoulder). When we raise our arms above our head, the muscles, tendons and bursa all raise up with our arm and bump into the acromion. Repeated bumps damage tendons, muscles and bursa and prolonged contact (such as keeping the arms raised) cuts off the blood supply, which also causes damage.

Signs and Symptoms

Early on, impingement syndrome feels like a dull ache in the shoulder and may make it difficult to sleep. Impingement syndrome may cause pain when raising the arm in front or to the side. However, a reliable sign is pain in reaching into the back pocket.

Tarsal tunnel syndrome affects the feet.

How it Happens

Tarsal tunnel syndrome is caused by compression of the posterior tibial nerve where it enters the foot. This MSD occurs in a way similar to carpal tunnel syndrome. The posterior tibial nerve enters the foot by passing through the tarsal. The tarsal tunnel is formed by the bones of the foot on one side and the flexor retinaculum on the other. Passing through this tunnel are the tendons, the posterior tibial nerve, an artery and several veins. Bones, and retinaculum are very tough and resist compression. The posterior tibial nerve, on the other hand, does not. Repeated irritation can cause the tendons to swell and put pressure on the posterior tibial nerve. Over time, this can damage the nerve.

Signs and Symptoms

Tarsal tunnel syndrome begins as a vague burning or tingling in the bottom of the foot. Activity usually causes the pain to become more severe. Since the nerves control muscle strength and dexterity as well as sensation, an affected foot may become weak and numb.

For more information, see Wikipedia.

Tendonitis affects the tendons, usually in the hands, elbows and shoulders.

How it Happens

Tendonitis is usually caused by repetitive use of the joint. This overuse causes the tendon to develop small tears and/or become inflamed.

Signs and Symptoms

Tendonitis results in pain and tenderness over the tendons at a joint. As tendonitis becomes more severe, the pain will start to radiate away from the joint. Common forms of tendonitis have been given their own names such as medial epicondylitis, lateral epicondylitis and De Quervain’s Tenosynovitis.

For more information, see the Mayo Clinic: Tendonitis.

Thoracic outlet syndrome affects the arms and hands.

How it Happens

Several blood vessels and nerves that lead to the arm pass through the thoracic outlet. The thoracic outlet is located near the shoulder under the collar bone, above the ribcage and between to scalene muscles. Thoracic outlet syndrome occurs when the nerves get compressed as they pass through the thoracic outlet. This compression can be caused by an extra first rib, an injury which causes the collar bone to bend downward or the scalene muscles to scar and thicken or through repeated/sustained activities that cause the thoracic outlet to become smaller and compress the nerves. Activities that can cause this compression are extending the arms forward, reaching overhead or slouching the shoulders forward, which lowers the collar bone and puts tension in the scalene muscles. Often activities such as combing or drying hair with a hair dryer or sleeping with arms over the head make the pain worse.

Signs and Symptoms

Thoracic outlet syndrome is very difficult to diagnose and may produce symptoms that can be mistaken for other MSDs such as carpal tunnel syndrome link. Symptoms can include a combination of pain, weakness, numbness and tingling, swelling, fatigue or coldness in the arm and/or hand.

For more information, see the US National Library of Medicine: Thoracic Outlet Syndrome.

Trigger finger affects one or more of the fingers or thumbs.

How it Happens

The tendons that flex the fingers pass through several ligaments called pulleys that attach the tendons to the bones of the finger. Repeatedly sliding through a pulley may cause the tendon to swell or form a permanent thickening called a nodule. As the nodule becomes larger, it becomes more difficult and uncomfortable to flex the fingers (causing the tendon to pass through the pulley).

Signs and Symptoms

Trigger finger produces pain and difficulty in flexing the fingers. This difficulty is often described as a “catching sensation” as the nodule pulls through the pulley. In severe cases, the nodule becomes so large that it becomes stuck in the pulley and the finger freezes in place.

For more information, see American Academy of Orthopaedic Surgeons.