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.

Internal Derangement of Knee


Related Terms

  • Knee Instability
  • Torn Ligament(s)
  • Torn Meniscus

Differential Diagnosis

Specialists

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

Comorbid Conditions

Factors Influencing Duration

Factors influencing length of disability depend on the nature of the derangement, fitness level and age of the individual, intervention requirements, adherence to a rehabilitation program, proper rest interval, job requirements, the development of complications, and the presence of comorbid conditions or prior injury to the knee. Any task that stresses an already compromised knee will prolong and exacerbate the problem.

Medical Codes

ICD-9-CM:
717 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee
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
717.40 - 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
717.6 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Loose Body in Knee; Joint Mice, Knee; Rice Bodies, Knee (Joint)
717.7 - Internal Derangement of Knee; Degeneration, Rupture (old), or Tear (old) of Articular Cartilage or Meniscus of Knee, Patella Chondromalacia; Degeneration [Softening] of Articular Cartilage of Patella
717.8 - Other Internal Derangement of Knee
717.81 - Other Internal Derangement of Knee, Old Disruption of Lateral Collateral Ligament
717.82 - Other Internal Derangement of Knee, Old Disruption of Medial Collateral Ligament
717.83 - Other Internal Derangement of Knee, Old Disruption of Anterior Cruciate Ligament
717.84 - Other Internal Derangement of Knee, Old Disruption of Posterior Cruciate Ligament
717.85 - Other Internal Derangement of Knee, Old Disruption of Other Ligaments of Knee; Capsular Ligament of Knee
717.89 - Other Internal Derangement of Knee, Other
717.9 - Unspecified Internal Derangement of Knee

Overview

Internal derangement is an old term that describes internal damage to the joint generally caused by trauma. It is a nonspecific term that usually must be further refined by history, physical exam, x-rays, and frequently MRI studies.

The knee joint is the largest of weight bearing joint in the body. It is a hinge joint that connects the rounded, bony ends (condyles) of the thigh bone (femur) and the shin bone (tibia) and is bounded in front by the knee cap (patella). Various ligaments, muscles, and tendons help confine joint motion within safe limits while the menisci and cartilage cushion the joint against considerable forces that bear on the knee. Damage from injury or chronic overuse to any of these stabilizing and cushioning structures results in pain and may lead to joint instability.

With the popularity of jogging and skiing and the vulnerability of major sports figures to career-ending knee injury, terms of joint pathology have come into common usage and in many cases have supplanted the term internal derangement. Ligament tears are especially common. The knee has four major ligaments and each is vulnerable to injury: the anterior cruciate ligament (ACL), the medial collateral ligament (MCL) the posterior cruciate ligament (PCL) and the lateral collateral ligament (LCL). Each ligament restricts certain abnormal movement of the knee. Motion beyond the limits of the ligaments will produce damage manifested by a partial or complete tear. Cartilage damage is another common problem. The specialized cartilage cushion between the femur and tibia (meniscus) can be damaged in the same manner as the ligaments and may even be damaged at the same time. Articular cartilage is the smooth layer that covers the joint surfaces in the knee. Damage to the articular cartilage is referred to as chondromalacia. The most common example of chondromalacia is the cracking and popping (crepitus) that many people feel under their knee cap (See Meniscus Disorders; Patella Chondromalacia; Fracture, Patella; and Sprains and Strains, Knee).

Incidence and Prevalence: Knee pain is reported by about 20% of adult Americans and accounts for nearly 3 million outpatient and emergency room visits in the US annually (Levy). Among workers, traumatic knee injury is the second most common occupational accident. The MCL is the ligament most commonly injured, but damage to the ACL is the most common source of chronic joint instability (Levy).

Source: Medical Disability Advisor



Causation and Known Risk Factors

The knee is especially susceptible to injury because it carries the body's weight and its stability depends on a complex of ligaments, tendons, muscle, and cartilage. Although the knee can withstand large vertical forces, it remains vulnerable to horizontal and twisting forces. The risk for knee injury increases with participation in sports such as football, skiing, soccer, and basketball. Injuries to the ligaments and menisci occur most often in a range of young to middle-aged adults. Children and adolescents are the more likely to experience damage to the bones rather than to the ligaments of the knee joint. Females are more vulnerable to patellar and lateral meniscus problems (Levy).

Source: Medical Disability Advisor



Diagnosis

History: There is surprisingly little pain, while in other cases any movement at all seems to elicit tremendous pain. The joint may be unstable, and the patient often describes crepitus or locking of the joint. History will include cause (mechanism) of the injury; duration, degree, location, character of the pain; and the extent and pattern of knee dysfunction and disuse.

Physical exam: A physical exam will often reveal a variety of confirming evidence. Such injury responses as edema, abrasions, lacerations, and dislocation of the patella are readily apparent following a traumatic event. Muscle wasting indicates disuse from a condition that would have occurred several weeks or longer ago. Touching (palpating) and manipulating the joint often reveals such problems as ligament instability, meniscal injuries, or partial displacement of the patella (patellar subluxation).

Tests: Modern diagnostic methods, including plain x-ray (radiograph), CT scans, MRI, and arthroscopy permit specific diagnosis of the various injuries that can cause internal derangement in the knee. Plain radiographs are a useful screening tool to assess joint surfaces and bony structures, but only 15% of these films reveal the full nature of the condition (Levy). MRI is used most commonly and allows visualization of the less dense structures such as ligaments, menisci, and tendons. Bone fractures are often better visualized using CT scans. Ultrasound may be helpful in distinguishing other conditions such as cysts, aneurysms, and blood clots (thrombophlebitis), although it would not generally be necessary if MRI were available. Withdrawing (aspirating) and analyzing knee joint fluid (joint effusion) helps diagnose infection and inflammatory arthritis. Arthroscopy is an invasive surgical procedure and is usually done to confirm the diagnosis and treat the problem.

Source: Medical Disability Advisor



Treatment

Treatment depends on the nature and severity of the condition and the health, age, and activity requirements of the patient. Mild injuries and tears may require nothing more than the standard RICE regimen (rest, ice, compression, elevation), while more serious conditions may call for surgical intervention and a strict rehabilitation program.

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

Internal derangement of the knee describes a variety of conditions with varying severity. Prognosis will depend on the nature and severity of the condition, available treatments, and the health status, age, and activity requirements of the patient.

Source: Medical Disability Advisor



Rehabilitation

Internal derangement of the knee may involve injury to muscle, ligament, tendon, meniscus, or bone. Rehabilitation will depend on the nature of the underlying pathology, the extent of injury, type of treatment (i.e., surgical, nonsurgical), and the functional goals of the individual.

The primary focus of rehabilitation for internal derangement of the knee is to control pain and swelling and regain function. Physical therapy may be initiated according to the recommendations of the physician to restore range of motion and strength to the involved knee. Initially, the therapist may use modalities such as electrical stimulation and cold (cryotherapy) to reduce swelling and control edema. Therapists may instruct individuals to use assistive devices (i.e., walker, crutches, cane) according to weight bearing status to promote independent ambulation. Isometrics, followed by open and closed chain strengthening exercises, are progressed as tolerated with emphasis on function. As knee flexibility and strength return, individuals may progress to balance and proprioception activities until full function is achieved.

As part of the rehabilitation program, individuals are instructed in a home exercise program that usually should be continued after discharge to maximize return of knee strength and stability. The treating physician should guide the resumption of heavy work and sports activities.

Source: Medical Disability Advisor



Complications

Uncomplicated recovery from internal derangement of the knee depends on timely and accurate diagnosis, the nature of the condition, adherence to recovery schedules and rehabilitation recommendations, and the avoidance of further aggravation to the knee.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Individuals whose jobs require prolonged standing may need temporary reassignment to sedentary duties. Some individuals may be instructed to wear a protective brace to facilitate healing. Limitations on how much weight may be borne by the affected leg will restrict walking and climbing and may necessitate the use of crutches, a walker, or cane. If assistive devices are prescribed, relocation to an accessible area of the workplace may be required, along with additional safety precautions. Individuals should avoid squatting, crawling, or kneeling. They may need frequent rest periods that allow for elevation of the lower leg. Other activities that need to be avoided include jumping, twisting, heavy lifting, pushing, or lunging. Company policy on medication usage should be reviewed to determine if pain medication use is compatible with job safety and function. Individuals whose injuries do not require surgical repair or reconstruction may nonetheless need time off from work to undergo extensive physical therapy to regain function. If an individual does require surgery, squatting, kneeling and crawling may need to be limited permanently.

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:

  • Did the pain or swelling result from a fall, twisting injury, or blow from an object or person (blunt force trauma)?
  • Is the shape of the knee distorted?
  • Is there pain or tenderness over the kneecap?
  • Has individual undergone diagnostic tests such as x-ray, MRI, CT scans, arthroscopy, or ultrasound?

Regarding treatment:

  • Does individual have a mild injury that resolved without treatment?
  • Does the knee derangement require rest and rehabilitation?
  • Does the injury call for surgical intervention?
  • Does the derangement require professional rehabilitation guidance?

Regarding prognosis:

  • Is individual's employer able to accommodate any necessary work restrictions?
  • Does individual have any underlying conditions or complications that may affect the ability to recover?
  • Is individual compliant with the recommended program of rest and rehabilitation?
  • Has the individual experienced previous knee injury?

Source: Medical Disability Advisor



References

Cited

Levy, David, Howard Dickey-White, and June Sanson. "Knee Injury, Soft Tissue." eMedicine. Eds. Eric Kardon, et al. 12 Dec. 2008. Medscape. 18 Feb. 2009 <http://emedicine.medscape.com/article/826792-overview>.

General

"Common Knee Injuries." American Academy of Orthopaedic Surgeons. Aug. 2007. American Association of Orthopaedic Surgeons. 18 Feb. 2009 <http://orthoinfo.aaos.org/topic.cfm?topic=A00325>.

Source: Medical Disability Advisor






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