Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Impingement Syndrome


Related Terms

  • Internal Derangement of the Shoulder
  • Internal Impingement
  • Painful Shoulder
  • Rotator Cuff Impingement Syndrome
  • Subacromial Impingement Syndrome
  • Subcoracoid Impingement

Differential Diagnosis

Specialists

  • Occupational Therapist
  • Orthopedic (Orthopaedic) Surgeon
  • Physiatrist (Physical Medicine and Rehabilitation Specialist)
  • Physical Therapist
  • Rheumatologist

Comorbid Conditions

  • Biceps tendon rupture
  • Musculoskeletal disorders
  • Rheumatologic disorders
  • Shoulder instability
  • Tear in the contralateral shoulder

Medical Codes

ICD-9-CM:
718.81 - Other Joint Derangement, Not Elsewhere Classified; Flail Joint (Paralytic); Instability of Joint, Shoulder Region; Acromioclavicular Joint(s); Glenohumeral Joint(s); Sternoclavicular Joint(s); Clavicle; Scapula

Overview

© Reed Group
Impingement syndrome is a term used to describe a disorder in which one or more soft tissues (rotator cuff tendons, bursa and biceps tendons) surrounding the ball of the shoulder joint get pinched, or impinged, on the bony surface under a portion of the shoulder blade (the acromion).

The shoulder is made up of three bones (humerus, scapula, and clavicle). The rotator cuff comprises four muscles—the subscapularis, the supraspinatus, the infraspinatus and the teres minor—and their musculotendinous attachments The tendons that attach these four muscles in the shoulder area to the humerus, fuse together to form the rotator cuff. The lateral extension of the shoulder blade is the acromion, and the area underneath it is the subacromial space. A lubricating sac of tissue protects the tendons as they move between the acromion and the glenohumeral joint (subacromial bursa). Usually there is enough room between the acromion/acromioclavicular joint and the glenohumeral joint for the rotator cuff and biceps tendons to slide easily underneath the acromion as the arm is raised. Any process which compromises this normal gliding function may lead to mechanical impingement (Schaffer). Common conditions include weakening (degeneration) of the muscles or tendons due to age, formation of bone spurs and / or inflammatory tissue. For example, when the space is made smaller, either by changes in the shape (hypertrophy) of the acromion and / or acromioclavicular joint or by bone spurs, the rotator cuff is forced to rub against the arch of the acromion. Impingement is thought to be a precursor to a rotator cuff tear. Impingement can also cause the bursa or tendons to become inflamed, resulting in bursitis and tendinitis, respectively (Papadonikolakis).

Age, repetitive overhead activity, shoulder looseness (laxity), sleeping with the shoulder abducted, previous injury, osteoarthritis with resulting bone spurs (osteophytes), and anatomical abnormalities are all causative factors. Shoulder laxity that allows the head of the upper arm bone (humerus) to ride high in the shoulder joint will force the rotator cuff against the arch, resulting in impingement. Instability simulating impingement is usually seen in young athletes with a history of significant shoulder injury. As people age, some structures slowly enlarge. Thickening of the acromion and the acromioclavicular joint that occur with age, and the development of osteophytes (spurs) on the underside of the acromion and acromioclavicular joint, are the most common causes of shoulder impingement.

Usually, the acromion has a flat inferior or lower surface (Type I acromion). Some individuals have a congenital anomaly in which the underside of the acromion is hooked or curved (Type II or III), meaning there is less room for the rotator cuff because of a congenital difference in the space available for the cuff tendons.

Shoulder impingement can have multiple causes. Understanding the functional anatomy is the key to understanding shoulder disorders (Fongemie). The rotator cuff (muscles and tendons) are the dynamic stabilizers of the glenohumeral joint. The static stabilizers are the capsule and labrum complex which include the glenohumeral ligaments. The joint formed by the bones (humerus and glenoid (of the scapula) are unstable (would fall apart) but for the static and dynamic stabilizers. Without an intact rotator cuff, the unopposed deltoid would pull the humeral head up into the acromion.

In the past, the diagnosis of shoulder impingement was often used when a specific diagnosis for shoulder pain could not be determined (Papadonikolakis) However, with improving diagnostic examinations and clinical studies, the specific cause of the impingement can be determined and the treatment directed to the specific cause. This has resulted in better outcomes.

Incidence and Prevalence: No documented information on the occurrence of shoulder impingement syndrome exists (DeBerardino).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Excluding impingement that results from sports that stress the shoulder (such as competitive swimming or throwing), impingement syndrome more commonly develops after the age of 30. Individuals who are at risk of developing impingement syndrome include athletes (e.g., baseball players), assembly-line workers, warehouse workers, and others who perform repetitive work with the arms raised above shoulder height. Refer to "Disease and Injury Causation," page 184.

Conditions that predispose individuals to impingement syndrome includes those that alter the normal gliding function of the shoulder such as bone spurs, osteoarthritis, shoulder injuries and degenerative diseases.

Source: Medical Disability Advisor



Diagnosis

History: The hallmark symptom of impingement syndrome is shoulder pain that is most often gradual and progressive over time. This type of shoulder impingement is commonly due to degenerative changes. Acute onset of pain is often linked to a traumatic event. In the early stages, individuals will experience pain only when the arm is held out from the side or in front of the body with the elbow at or above shoulder level, and the pain will be relieved with rest. There may be a "catching" sensation when the arm is lowered. As the impingement syndrome becomes more chronic, pain is felt most with shoulder activity but will not be relieved with positional change or rest. Night pain, often disturbing sleep, particularly when the patient lies on the affected shoulder is common. Shoulder pain may be so severe that it prevents the individual from moving his or her shoulder, which can lead to adhesive capsulitis. Pain is also frequently felt at night and may be severe enough to interfere with sleep, particularly when the individual rolls onto the affected shoulder. There may be a clicking or popping sensation felt with arm motion. The individual may have an occupation that requires repetitive arm motions. Complaints of weakness or the inability to raise the arm may indicate that the rotator cuff tendons are actually torn.

Physical exam: Pain will be evident in individuals as the physician elevates the arm and positions the shoulder in a 90-degree forward-flexed with 90-degees of elbow flexion and then internally rotated the arm (Hawkins impingement sign), or in maximal forward flexion (Neer impingement sign). Pain may occur at a particular point in the arc of motion but disappear as motion proceeds (called "painful arc"). Pain may also be elicited by resisted arm elevation during muscle strength testing. Range of motion testing will reveal limitations, most commonly in abduction and internal rotation. Individuals may exhibit total relief of symptoms after injection of a local anesthetic into the subacromial space (injection test). Pressure on the subacromial region produces pain (Marx).

Tests: Routine shoulder x-rays, including special views of the acromial arch, are used to evaluate the shape of the arch and rule out other diagnoses. For most individuals, MRI is the imaging study of choice for shoulder pathology (DeBerardino). It is noninvasive and can be used to measure the amount of room for the rotator cuff, determine whether tendinitis is present in the cuff tendons (increased signal), determine whether osteophytes or acromioclavicular joint hypertrophy are producing impingement, detect rotator cuff tears, and detect other pathology (such as biceps tendinitis, biceps rupture, or labrum tear). Diagnostic ultrasound or shoulder joint arthrography (x-rays obtained after injecting a contrast medium, such as iodine solution) are alternatives that examine the integrity of the rotator cuff.

Source: Medical Disability Advisor



Treatment

In the early stages, impingement syndrome will resolve when the aggravating activity and any overhead work are modified. Physical therapy to increase range of motion and strengthen shoulder stabilizers may also be helpful. Application of ice (cryotherapy) can relieve pain. Medications to control pain and inflammation are usually prescribed. Injection of corticosteroid and anesthetic agents into the subacromial space is often part of conservative treatment. If the shoulder becomes stiff (complicating adhesive capsulitis), manipulation of the shoulder under anesthesia can be helpful to improve flexibility. For information on activity modification, see “Ability to Work,” page 179.

Surgical intervention is an option when individuals fail to improve after several months of physical therapy and subacromial injections (Hegmann). The goal of surgery is to increase the size of the subacromial space and remove or repair the inflamed tissue. Reshaping the acromion (acromioplasty) combined with removing the subacromial bursae and cutting the coracoacromial ligament are common procedures. Removal (excision) of any bone spurs and inflamed rotator cuff tissue (débridement) may also be needed. This combination of procedures is often called subacromial decompression. These procedures can be performed either through open surgery (arthrotomy) or arthroscopically. Removal of the distal clavicular bone spur is not considered an excisional arthroplasty of the acromioclavicular joint (Melhorn; Brooks).

If a labrum tear is present, it can be repaired or débrided at the time of the shoulder surgery. Typically, these are outpatient procedures.

Source: Medical Disability Advisor



ACOEM

ACOEM's Practice Guidelines, the gold standard in effective medical treatment of occupational injuries and illnesses, are provided in this section to complement the disability duration guidelines.*
 
Shoulder Disorders
 
* The relationship between the MDGuidelines (MDA) content and ACOEM's guidelines is approximate and does not always link identical diagnoses. The user should consult the diagnostic codes in both guidelines, as well as the clinical descriptions, before assuming an equivalence.

Source: ACOEM Practice Guidelines



Prognosis

The outcome for impingement syndrome is usually good to excellent but is dependent on age and job activities. One study found that awkward posture, forceful effort, job demand, and decision control are predictors of chronic shoulder pain at work (Herin).

Absence of red flags, work-related shoulder disorders may generally be safely and effectively managed by non-operative means. The focus is on using the most efficacious treatment strategy(ies), monitoring for progression and complications, modifying treatment to facilitate the healing process, and facilitating return to work in a modified- or full-duty capacity. Including patient's treatment preferences may be helpful (Croft).

Workers' compensation status is associated with higher costs, worse prognosis, and worse outcomes than patients without workers' compensation status or litigation (Hegmann).

Source: Medical Disability Advisor



Rehabilitation

Impingement syndrome is often classified into three developmental stages (Miller). In all three stages the early goals are to decrease pain and inflammation and reduce the pressure on the irritated tendon and / or tissues (Miller; Rubin). In conjunction with pharmacological management, the therapist will instruct individuals in the use of cold treatments to the shoulder to decrease inflammation. Past research does not support the use of ultrasound for the treatment of impingement syndrome (Philadelphia Panel). Modalities may be beneficial for palliative relief of symptoms. Reduction of stress to the irritated tissue is often achieved through patient education, ergonomic adjustments, and / or activity modifications aimed at reducing the offending activities. These offending activities often include repetitive movements or sustained positions where the elbow is raised above the shoulder level. Stiffness may be prevented by passive range of motion exercises conducted during supervised rehabilitation and a home exercise program.

Although a downward curved acromion has been observed in individuals with impingement syndrome, the condition is frequently asymptomatic and therefore not an indication for surgery (Gartsman; Hirano). Many times, reversible rotator cuff muscle weakness and age-related degenerative changes are contributing factors to impingement syndrome, and are amenable to therapeutic intervention that includes rotator cuff strengthening and joint capsule stretching (Miller).

Stage I occurs in individuals who are less than 25 years old. Treatment focuses on improving strength and stability of the muscles of the shoulder girdle. These muscles include those that attach from the upper arm to the shoulder blade, as well as those that attach from the shoulder blade to the upper back (i.e., thoracic spine) (Miller, Rubin). These exercises will help to restore the normal glenohumeral (scapula and humerus) motion pattern and often involve resistance in the form of elastic, weights, or manual resistance provided by the therapist. The individual may also perform some stretching exercises (Bowen).

Stage II occurs in individuals between 25 and 40 years of age. Strengthening exercises are performed as in stage I. However, because the joint capsule becomes stiffer with age, a greater emphasis is placed on flexibility and stretching exercises. In addition, the therapist may apply manual stretching techniques to the individual’s arm, shoulder blade, and the upper portion of the thoracic spine. These techniques are aimed at improving the mobility in and around the shoulder to restore the normal glenohumeral motion pattern so the subacromial space can be maintained during movement. Some recent evidence from randomized controlled trials suggests that the addition of manual therapy to a program of strengthening and stretching is superior to patient strengthening and stretching alone (Senbursa).

Stage III occurs in individuals over age 40. Because these individuals are older and stiffer as mentioned in stage II, the role of patient self-stretching and manual stretching treatments is often greater. Strengthening exercises are performed as in stages I and II.

The impingement at any stage may progress to a partial or full tear of the rotator cuff tendon. In addition to undergoing supervised rehabilitation, the individual should be instructed in a home exercise program to be practiced daily, and continued independently after the completion of rehabilitation (Ludewig). See Rotator Cuff Syndrome for further details on therapy.

FREQUENCY OF REHABILITATION VISITS
Nonsurgical
SpecialistImpingement Syndrome
Occupational or Physical TherapistUp to 12 visits within 4 weeks
Surgical
SpecialistImpingement Syndrome
Occupational or Physical TherapistUp to 16 visits within 6 weeks
The table above represents a range of the usual acceptable number of visits for uncomplicated cases. It provides a framework based on the duration of tissue healing time and standard clinical practice.

Source: Medical Disability Advisor



Complications

Rotator cuff degeneration and tear, biceps tendinitis, frozen shoulder (adhesive capsulitis), and reflex sympathetic dystrophy could complicate impingement syndrome.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Aggravating activities need to be limited until symptoms have improved. During early treatment, the individual should limit lifting, carrying, pushing, or pulling heavy objects. Individuals should limit use of the arm with the hand above shoulder level. These guides are rarely permanent. An ergonomic evaluation of the workplace may be helpful. A change in job duties, sharing or alternating tasks, a reduced work rate, more frequent rest breaks, and limits on the time and frequency of repetitive activities may be reasonable. Work-site modifications might include forearm rests for individuals who use computer keyboards frequently, headsets for those who answer telephones and modifications to repetitive activities so that they can be done without or limiting raising the arms overhead. For example, using a single step for a short-statured individual that can be removed for a taller individual may be a reasonable accommodation. Individual attention and education can encourage recognition and avoidance of aggravating activities, awareness of shoulder mechanics and early signs of impingement syndrome, and use of proper warm-up techniques.

For more information on potential risk factors and activity modification, refer to “Ability to Work,” page 181, table 12-1.

Risk: Re-injury is possible, but most individuals are on modified work. For more information, refer to “Ability to Work,” page 181, table 12-1.

Tolerance: Tolerance is the limiting issue for shoulder impingement. Non-surgical treatment will often result in improvement. However, the length of time can be long and most individuals want a quick fix (Melhorn). The ability to work through the pain is unique to each individual. Education can modify tolerance.

Source: Medical Disability Advisor



Maximum Medical Improvement

30 to 60 days, non-surgical treatment, once stable and symptoms improve.

60 to 120 days, surgical.

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Does individual have any risk factors or predisposing conditions such as work or sports that stress the shoulder, bone spurs, osteoarthritis, shoulder injuries, or degenerative disease?
  • Did the shoulder pain appear suddenly (suggests another diagnosis) or was the onset gradual and progressive (suggests impingement)?
  • Was there pain following an injury?
  • What symptoms does individual have?
  • What were the findings on physical exam?
  • Has individual undergone shoulder x-rays, MRI, ultrasound, or arthrography to establish the diagnosis?
  • Have conditions with similar symptoms been ruled out?

Regarding treatment:

  • Has individual responded favorably to conservative treatment?
  • Did individual undergo shoulder manipulation under anesthesia for complicating adhesive capsulitis? Was surgery performed? What type? Were there complications from surgery?

Regarding prognosis:

  • Is recovery prolonged due to surgery?
  • Is individual active in physical therapy? In a home exercise program?
  • Is individual's employer able to accommodate the necessary restrictions?
  • Does individual have osteoarthritis, rheumatoid arthritis, shoulder injuries, shoulder instability, or shoulder degeneration?
  • Does individual have complications such as rotator cuff tear, biceps tendinitis, bursitis, or frozen shoulder?
  • Is the affected shoulder on the individual’s dominant or nondominant side?

Source: Medical Disability Advisor



References

Cited

Bowen, Jay E., and Gerald A. Malanga. "Chapter 14 - Rotator Cuff Tendinitis." Essentials of Physical Medicine and Rehabilitation. Eds. Walter R. Frontera, Julie K. Silver, and Thomas Rizzo. 2nd ed. Philadelphia: Saunders, Elsevier, 2008.

Brooks, C. N. , J. B. Talmage, and J. M. Melhorn. "Rating Distal Clavicle Resection." The Journal of the American Medical Association (2012): 13-15.

Croft, Thomas E. , et al. "What influences participants' treatment preference and can it influence outcome? Results from a primary care-based randomised trial for shoulder pain." British Journal of General Practice 54 (499) (2004): 93-96.

DeBerardino, T. M., and Wing K. Chang. "Shoulder Impingement Syndrome." eMedicine. Eds. A. D. Perron, et al. 29 Nov. 2012. Medscape. 31 Jan. 2013 <http://emedicine.medscape.com/article/92974-overview>.

Fongemie, Allen, et al. "Management of Shoulder Impingement Syndrome and Rotator Cuff Tears." American Family Physician 57 (4) (1998): 667-674.

Gartsman, G., and D. O'Connor. "Arthroscopic rotator cuff repair with and without arthroscopic subacomial decompression: A prospective, randomized study of one-year outcomes." Journal of Shoulder and Elbow Surgery 13 4 (2004): 424-426.

Hegmann, K. T. , et al., eds. "Shoulder Disorders." Occupational Medicine Practice Guidelines: Evaluation and Management of Common Health Problems and Functional Recovery in Workers. Third ed. ACOEM, 2011. 1-378.

Herin, F. , et al. "Predictors of chronic shoulder pain after 5 years in a working population." Pain 153 11 (2012): 2253-2259.

Hirano, M., I. Junji, and K. Takagi. "Acromial shapes and extension of rotator cuff tears: Magnetic resonance imaging evaluation." Journal of Elbow Surgery 11 (2002): 576-578.

Ludewig, P. M., and J. D. Borstad. "Effects of a Home Exercise Programme on Shoulder Pain and Functional Status in Construction Workers." Occupational and Environmental Medicine 60 11 (2003): 841-849. National Center for Biotechnology Information. National Library of Medicine. 10 May 2008 <PMID: 14573714>.

Marx, R. G. , C. Bombardier, and J. G. Wright. "What do we know about the reliability and validity of physical examination tests used to examine the upper extremity." Journal of Hand Surgery 24A (1) (1999): 185-193.

Melhorn, J. M. 18th Annual Scientific Session. Eds. J. M. Melhorn and D. C. Randolph. American Academy of Disability Evaluating,

Melhorn, J. Mark, and William Ackerman, eds. Disease and Injury Causation, Guides to the Evaluation of. AMA Press, 2008.

Papadonikolakis, A. , et al. "Published evidence relevant to the diagnosis of impingement syndrome of the shoulder." Journal of Bone and Joint Surgery 93 (19) (2011): 1827-1832.

Philadelphia Panel. "Philadelphia Panel Evidence-Based Clinical Practice Guidelines on Selected Rehabilitation Interventions for Shoulder Pain." Physical Therapy 81 10 (2001): 1719-1730. National Center for Biotechnology Information. National Library of Medicine. 10 May 2008 <PMID: 11589645>.

Rubin, B. D., and E. Kitai. "Fundamental Principles of Shoulder Rehabilitation: Conservative to Postoperative Management." Arthroscopy 18 9 Suppl 2 (2002): 29-39. National Center for Biotechnology Information. National Library of Medicine. 10 May 2008 <PMID: 12426529>.

Senbursa, G., B. Baltaci, and A. Atay. "Comparison of conservative treatment with and without manual physical therapy for patients with shoulder impingement syndrome: a prospective, randomized, clinical trial." Knee Surgery, Sports Traumatology, Arthroscopy 15 (2007): 915-921.

Shaffer, Ben. "Shoulder Impingement." AOSSM. 2008. American Orthopaedic Society for Sports Medicine. 31 Jan. 2013 <http://www.sportsmed.org/uploadedFiles/Content/Patient/Sports_Tips/ST%20Shoulder%20Impingement%2008.pdf>.

Talmage, J. B. , J. M. Melhorn, and M. H. Hyman, eds. Work Ability and Return to Work, AMA Guides to the Evaluation of. Second ed. Chicago: AMA Press, 2011.

Talmage, J. B., ed. Advanced Clinical Topics. Philadelphia: American Academy of Disability Evaluating, 2003.

General

Miller, Robert H., and Jeffrey A. Dlaback. "Chapter 44 - Shoulder and Elbow Injuries." Campbell's Operative Orthopaedics. Eds. S. Terry Canale and James H. Beaty. 11th ed. Philadelphia: Mosby Elsevier, 2008.

Source: Medical Disability Advisor






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