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.

Meniscus Disorders, Knee


Related Terms

  • Injured Knee Cartilage
  • Meniscal Injury
  • Meniscus Lesion

Differential Diagnosis

  • Contusions
  • Knee osteochondritis dissecans
  • Ligament injuries (anterior or posterior cruciate)
  • Lumbosacral radiculopathy
  • Osteoarthritis
  • Patellofemoral joint dysfunction
  • Pes anserine bursitis
  • Rheumatoid arthritis
  • Tendon inflammation (tendinitis)
  • Tibial tubercle avulsion fracture

Specialists

  • Orthopedic (Orthopaedic) Surgeon
  • Physiatrist (Physical Medicine and Rehabilitation Specialist)
  • Physical Therapist
  • Sports Medicine Physician

Comorbid Conditions

Factors Influencing Duration

Length of disability is influenced by the severity of symptoms, region of meniscal tear, presence of underlying joint disease (e.g., osteoarthritis, rheumatoid arthritis), and type of surgery. Meniscal repairs and meniscal transplants require a period of immobilization for healing before rehabilitation can begin, and thus the disability duration will be longer for these procedures. Sustaining multiple injuries to the knee lengthens disability. Individuals who sit while they work may return sooner than those who stand. Nonsurgical treatment of meniscal tears usually interferes with heavy work.

Medical Codes

ICD-9-CM:
717.0 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Old Bucket Handle Tear of Medial Meniscus; Old Bucket Handle Tear of Unspecified Cartilage
717.1 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Anterior Horn of Medial Meniscus
717.2 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Posterior Horn of Medial Meniscus
717.3 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Medial Meniscus, Other and Unspecified; Degeneration of Internal Semilunar Cartilage
717.4 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Lateral Meniscus
717.40 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Lateral Meniscus, Unspecified
717.41 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Bucket Handle Tear of Lateral Meniscus
717.42 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Anterior Horn of Lateral Meniscus
717.43 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Posterior Horn of Lateral Meniscus
717.49 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Lateral Meniscus, Other
717.5 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Derangement of Meniscus, Not Elsewhere Classified; Congenital Discoid Meniscus; Cyst of Semilunar Cartilage; Derangement of Semilunar Cartilage NOS
836.0 - Dislocation of Knee; Tear of Medial Cartilage or Meniscus of Knee, Current; Bucket Handle Tear: NOS Current Injury, Medial Meniscus Current Injury
836.1 - Dislocation of Knee; Tear of Lateral Cartilage or Meniscus of Knee, Current
836.2 - Dislocation of Knee; Other Tear of Cartilage or Meniscus of Knee, Current; Tear of: Cartilage (Semilunar) Current Injury, Not Specified as Medial or Lateral; Meniscus Current Injury, Not Specified as Medial or Lateral

Overview

© Reed Group
Knee meniscus disorders involve the medial meniscus or lateral meniscus, two semicircular pads of cartilage in the knee between the joint surfaces (femoral and tibial condyles) of the upper leg bone (femur) and lower leg bone (tibia). Menisci serve as shock absorbers. The most common meniscus disorder is a tear. The medial meniscus is more commonly torn than the lateral, because it is more firmly anchored to the joint capsule and surrounding ligaments. Tears are classified according to location, shape, size, and stability. The major classes of tears include the vertical longitudinal, oblique (often called parrot-beaked, or flap tear), displaced (bucket handle), degenerative, transverse, horizontal, or complex (involving multiple tears). Oblique and vertical longitudinal tears are the most common.

In young individuals, meniscal tears are usually caused by trauma, especially trauma involving a twisting or pivoting of the knee. In older individuals, there may be a gradual degeneration of the meniscus with no single causative event. As older individuals develop osteoarthritis of the knee, the menisci develop degenerative changes as well, and these can look like tears on imaging studies.

Symptomatic meniscal tears usually require surgery because the meniscus has a relatively poor blood supply and does not heal easily without intervention. Only the peripheral 10% to 30% of the medial meniscus and 10% to 25% of the lateral meniscus is well-vascularized (Kocher) and thus capable of healing. If a peripheral tear is in the vascularized portion of the meniscus, it may heal if it is surgically repaired. However, if such a peripheral tear is not surgically repaired, repetitive knee motion typically prevents the tear from healing, and over time it may lengthen, worsening the original tear. The more common location for tears is in the non-vascularized portion of the meniscus. This portion of the meniscus gets its nutrition from the joint fluid (synovial fluid), and without a blood supply it is not capable of healing. Thus, for these tears the surgeon can remove the central torn portion of the meniscus (partial menisectomy) or remove the entire meniscus and replace it with an allograft (meniscal transplant).

Incidence and Prevalence: Knee injury is the second most common work-related accident. More than 3 million Americans have knee injuries each year, and the meniscus is the most commonly injured part of the knee (Levy). In the US, 61 of out every 100,000 people have experienced a meniscal tear. The incidence of meniscus surgery in the US is 850,000 per year (Baker).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Individuals who have a previous knee injury, an abnormally shaped (discoid) meniscus, or tight, weak muscles or who walk on the insides of the feet (gross pronation) are at risk for knee injuries.

Meniscus tears occur 2.5 times more frequently in males than females (Baker), although disorders of the lateral meniscus occur more often in women. The peak incidence of meniscus tears is 31 to 40 years of age in males and 11 to 20 years in females (Baker). A second peak of meniscus tears caused by age-related degeneration occurs in people over age 60. (Levy).

Source: Medical Disability Advisor



Diagnosis

History: In younger individuals, there is usually a history of trauma. The individual may recall feeling a popping or snapping sensation when the trauma occurred. In older individuals, the trauma may be nonspecific, such as repeated squatting or kneeling. The individual may complain of knee pain, swelling, limited range of motion, and a clicking sound. Locking (an inability to straighten the knee) or buckling (a sudden giving way of the knee) may occur.

Physical exam: The exam may reveal tenderness over the medial or lateral joint line of the knee. There may be evidence of fluid buildup (effusion) in the joint. Squatting may cause pain. Tests that apply rotational and axial compression forces to the knee (such as Apley's compression test or McMurray's test) often reveal a palpable click or localized pain suggestive of meniscal injury.

Tests: Plain x-rays are not diagnostic but can rule out fracture, arthritis, and most loose bodies. MRI is a non-invasive method of evaluating the condition of the menisci and is the standard imaging method used. On MRI, the menisci of older individuals may show evidence of aging that is not related to injury. Individuals who cannot undergo MRI testing may be evaluated by an arthrogram (x-rays taken after dye is injected into the joint) or CT arthrogram. The interior of the joint can be examined directly by exploratory arthroscopy, the insertion of a very small viewing scope (arthroscope) into the knee joint through a small surgical opening. The diagnostic accuracy, sensitivity, and specificity of arthroscopy approach 100% (Baker). If indicated, arthroscopic surgery to trim or repair a meniscal tear may be performed at the same time.

Source: Medical Disability Advisor



Treatment

Smaller meniscal tears with mild, tolerable symptoms may be treated with rehabilitative exercise, activity modification, and analgesics in individuals unwilling to undergo surgery. More symptomatic meniscus injuries are treated surgically. Successful surgery preserves as much of the meniscus as possible while offering relief of symptoms. Some meniscal tears can be repaired by suturing. The surgeon must determine the possibility of repair at the time of surgery. Meniscus repair is generally reserved for younger individuals, and it is estimated that only 10% to 15% of meniscal tears are reparable (Phillips). Most tears require removal of the damaged part of the meniscus (subtotal or partial meniscectomy). Subtotal meniscectomy removes the minimum amount necessary so as to leave behind the maximum amount of undamaged meniscus. Subtotal meniscectomy is preferable to total meniscectomy even though remaining meniscal tissue may be subject to subsequent tears or degeneration (Phillips). Subtotal menisectomy is the most commonly performed meniscal surgery. Because removal of the entire meniscus (complete or total meniscectomy) leads to bone remodeling and cartilage degeneration (osteoarthritis), it is avoided whenever possible. If a complex tear requires total menisectomy in a younger person who does not yet have significant arthritic change in the knee, the option of meniscal transplant may be considered.

Arthroscopy is now the standard of care for meniscal surgery. Arthroscopy has the advantage of producing less pain and a quicker recovery. However, arthroscopic meniscectomy is occasionally difficult, depending on the type and location of the tear and the presence of adhesions. In those cases when the entire meniscus must be removed, open surgery may be preferable to avoid damaging the articular surfaces.

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.*
 
Knee 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 of meniscectomy depends on the location, severity of the tear, and the repair technique used. Meniscus repairs fail to heal in 5% to 10% of individuals (Baker). Following meniscus surgery, most people can return to all previous activities, including athletics, although the shock-absorbing capacity of the knee after a meniscectomy is reduced by about 20% (Kocher). Meniscus injury may predispose the individual to develop osteoarthritis in the involved knee. Progressive joint deterioration occurs following partial or complete meniscectomy. Long-term outcome of meniscal reconstruction is unknown.

Source: Medical Disability Advisor



Rehabilitation

The primary focus of rehabilitation for a meniscus disorder of the knee is to control pain and restore function. The rehabilitation program will depend on the extent of injury, length of time since injury, integrity of the knee joint, possibility of surgery, and the functional goals of the individual. It is not clear that a partial meniscectomy is beneficial; middle-aged and older patients may achieve good functional outcomes without arthroscopy and with therapy only (Lento; Herrlin).

Initially, if pain is an issue, modalities such as heat and cold may be used as indicated (Braddom). Additionally, cold may be used to control the edema often associated with meniscus disorders. Gait training with an assistive device may be necessary for independent ambulation; the treating physician will determine the individual's ability to bear weight on the affected knee.

The next goal is to restore motion and strength to the involved knee, with exercise progression according to the recommendations of the physician. Knee range of motion exercises can help to restore full mobility to the joint. Therapy should progress to strengthening exercises as tolerated. Throughout the period of strengthening, therapy should include flexibility exercises. Although strong muscles around the joint are critical, flexibility of the same muscle groups must be considered. It is important to emphasize closed chain exercises, in which the foot is stabilized, as well as open chain exercises, in which the foot is free to move, during this stage of rehabilitation (Lento). It may also be necessary to strengthen the adjacent joints if limited weight bearing was necessary after the injury.

The therapist should continue to use modalities as needed to control pain and swelling, and the therapist should instruct individuals in a home exercise program to be performed independently, complementing the supervised exercise regimen.

When full, pain-free motion is regained and the individual has sufficient strength for all activities of daily living, the individual may be progressed to balance and proprioceptive exercises. The extent of these exercises will be determined by the physician, individual, and physical therapist (Boyd).

Prior to discharge from physical therapy, individuals should understand both the need for continued exercise to maintain the stability of the knee joint and ways to protect the joint during work and leisure activities. Although a meniscus can heal within approximately 12 weeks, the joint should be protected from heavy loading and from pivoting movements until the meniscus has regained its full strength. Post surgical treatment progresses more slowly depending on the procedure, and athletes may take as long as 16 to 24 weeks before return to athletic activities (Lento).

FREQUENCY OF REHABILITATION VISITS
Nonsurgical
SpecialistMeniscus Disorders, Knee
Physical TherapistUp to 16 visits within 6 weeks
Surgical (meniscectomy)
SpecialistMeniscus Disorders, Knee
Physical TherapistUp to 12 visits within 6 weeks
Surgical (meniscus repair)
SpecialistMeniscus Disorders, Knee
Physical TherapistUp to 24 visits within 12 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

Once a meniscal tear occurs, the knee becomes less stable. Instability may cause the initial tear to enlarge further, creating the need for surgical treatment. In addition, the knee’s altered movements following a tear may damage joint surfaces over time and predispose individuals to osteoarthritis. The trauma that led to a meniscal tear may also have caused torn knee ligaments. In older individuals, degenerative changes to the knee may accompany meniscal injuries.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

The individual may need to use crutches or a cane temporarily when walking. Standing and walking may need to be limited temporarily. Squatting, kneeling, and crawling may need to be limited permanently. Increased awareness of the knee’s position while twisting, turning, or lifting, and reestablishing knee fitness, emphasizing strength and flexibility, will help prevent recurrent problems.

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 a history of trauma, especially twisting of the knee?
  • Did individual feel a popping or snapping sensation when the trauma occurred?
  • Does repeated squatting or kneeling cause pain?
  • Is knee swollen and does it have a limited range of motion?
  • Were x-rays done to rule out a fracture?
  • Was an MRI done to confirm the diagnosis? If not, was an arthrogram done?
  • Was meniscus examined directly by exploratory arthroscopy?
  • Was arthroscopic surgery done at the same time?
  • Is individual a candidate for meniscal reconstruction?

Regarding treatment:

  • Is individual actively participating in the rehabilitation regimen?
  • Has individual demonstrated an increase in range of motion at each physical therapy session?
  • Has a post-operative MRI been done to determine if additional surgery is indicated?
  • Is chondromalacia of the articular surface of the patella or of the weight bearing portion of the femur or tibia present on MRI or noted in the operation note?

Regarding prognosis:

  • What is extent and location of meniscal tear?
  • Was tear located in a region of the meniscus with no blood supply (avascular)? If so, was a partial menisectomy performed?
  • Has physical therapy been effective?
  • Is individual prolonging rehabilitation out of fear of sustaining another knee injury?
  • Are knee ligaments torn?
  • Is there evidence of joint deterioration?

Source: Medical Disability Advisor



References

Cited

Baker, Bradley S., and James Lubowitz. "Meniscus Injuries." eMedicine. Eds. Leslie Milne, et al. 6 May. 2008. Medscape. 22 Dec. 2008 <http://emedicine.com/sports/topic160.htm>.

Boyd, K. T., and P. T. Myers. "Meniscus Preservation; Rationale, Repair Technique and Results." Knee 10 1 (2003): 1-11. National Center for Biotechnology Information. National Library of Medicine. 8 Oct. 2008 <PMID: 12649021>.

Braddom, Randolph L. Physical Medicine and Rehabilitation. 3rd ed. Philadelphia: W.B. Saunders, 2006.

Herrlin, S., et al. "Arthroscopic or conservative treatment of degenerative medial meniscal tears: a prospective randomised trial." Knee Surgery, Sports Traumatology, Arthroscopy 15 4 (2007): 393-401. PubMed. 2 Nov. 2010 <PMID: 17216272>.

Kocher, M. S., K. Klingele, and S. O. Rassman. "Meniscal Disorders: Normal, Discoid, and Cysts." Orthopedic Clinics of North America 34 3 (2001): 329-340. MD Consult. Elsevier, Inc. 7 Oct. 2008 <http://home.mdconsult.com/das/journal/view/42760172-2/N/13817635?sid=290749551&source=MI>.

Levy, David. "Knee Injury, Soft Tissue." eMedicine. Eds. Eric Kardon, et al. 5 Aug. 2006. Medscape. 22 Dec. 2008 <http://emedicine.com/emerg/topic288.htm>.

Phillips, Barry B. "Arthroscopy of the Lower Extremity." Campbell's Operative Orthopaedics. Eds. S. Terry Canale and James H. Beaty. 11th ed. Philadelphia: Mosby Elsevier, 2008.

General

Lento, Paul, and Venu Akuthota. "Chapter 63 -Meniscal Injuries." Essentials of Physical Medicine and Rehabilitation. Eds. Walter R. Frontera, Julie K. Silver, and Thomas Rizzo. 2nd ed. Philadelphia: Saunders, Elsevier, 2008.

Source: Medical Disability Advisor






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