Rating repeat partial meniscectomies, unoperated meniscal tears, and meniscal repairs requires thoughtful clinical assessment and application of directives provided in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). Although the AMA Guides provide a specific impairment value for a partial meniscectomy, repeat meniscectomies may result in further impairment not to exceed the maximum value assigned for a total meniscectomy.

Assessment of impairment and disability experienced by patients with chronic pain is challenging. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) assesses impairment primarily based on objective findings, but pain is subjective. The sixth edition of the AMA Guides provides a pain-related impairment (PRI) of up to 3% in rare situations. Otherwise, pain is considered to be reflected in the conventional impairment rating system. There are still many unanswered questions.

This article is the fourth of five in a series on the effects of age-related changes in impairment evaluations as defined by the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ), Fifth and Sixth Editions. The present article addresses the musculoskeletal system and differs from the first three articles, which focused on apportionment of an impairment rating between aging and other causes. The medical literature supports the notion that age-related osteoarthritis (OA) changes in the hand and digits frequently are associated with injury and/or repetitive motion. Thus, apportionment is indicated, but deciding which came first, the imaging abnormality or the injury, requires consummate skill on behalf of the rating physician. OA also occurs in the knees and hips of older individuals. Diffuse idiopathic skeletal hyperostosis (DISH) is a noninflammatory disorder characterized by calcification and ossification of spinal ligaments and entheses and is unique, in the authors’ opinion, because of a positive correlation between aging and back pain caused by this condition. The article also addresses the association—or the lack thereof—between pathology and aging, as well as degenerative changes and symptoms, to facilitate causation analysis. For a fuller discussion of causation analysis for the spine, readers can consult the AMA Guides to the Evaluation of Disease and Injury Causation, Second Edition .

Complaints of spinal pain are common after motor vehicle collisions (MVCs), and evaluators may be asked whether the collision caused permanent injury to the spine, including aggravating intervertebral disc degeneration (IDD) and/or causing a disc herniation. To determine causality, evaluators can use the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ) to understand if a low-speed collision caused IDD. Injury causation analysis (ICA) is the scientific method used to analyze the mechanism and magnitude of injury for people who experience an MVC. ICA involves comparing the mechanical forces involved in the incident with the body's injury tolerance. Low back pain (LBP) is a common complaint following MVCs, but the literature regarding automobile collision testing has been compared to the body of evidence regarding real-world collision data and shows that, for low-speed impacts, any injuries are minor and self-limiting. Further, disability due to LBP was predicted by an abnormal baseline psychological test profile or a previously disputed compensation claim. The motions, forces, and accelerations generated in low-speed collisions are less than those encountered in activities of everyday living. ICA suggests that disc degeneration and disc herniations are pre-existing and are not caused by low-speed MVCs. Although the pain caused by a muscle sprain associated with a low-speed collision may prompt imaging studies that show disc pathology, these are coincidental and are not causally related.

Maximum medical improvement (MMI) and its multiple synonyms are important terms to understand because one cannot determine permanent impairment until a condition has resolved or reached a stable plateau with respect to improvement. Further, in many jurisdictions MMI represents the date beyond which temporary or all benefits cease or time-loss compensation (temporary disability benefits) may be terminated. Because each arena is to some extent unique, evaluating physicians should become familiar with MMI or the term used and its definition in the applicable federal, state, or provincial law or insurance policy. A table shows the terminology used by various US workers’ compensation jurisdictions, but there is no universal definition for MMI. The fourth edition of the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ) says only that “an impairment should not be considered ‘permanent’ until the clinical findings, determined during a period of months, indicate that the medical condition is static and well stabilized. The AMA Guides, Fifth Edition, defines MMI as “a condition or state that is well stabilized and unlikely to change substantially in the next year, with or without medical treatment” but acknowledges the possibility of “some change.” Similarly the sixth edition states that MMI is the “point at which a condition has stabilized and is unlikely to change (improve or worsen) substantially in the next year, with or without treatment”; signs and symptoms may wax and wane, but further recovery or deterioration is not anticipated.

The misuse of medical and legal terminology can be confusing and frustrating and also introduces the potential for errors; this article focuses on some of the most often misused terms applicable to injury and illness. A common example of anatomical imprecision involves the shoulder, and patients who complain of “shoulder pain” sometimes localize their discomfort in the trapezius or scapula rather than on the shoulder per se. The distinction between shoulder and upper back or shoulder girdle pain is not merely terminological nitpicking but rather is of clinical significance. Similarly, no terms are more commonly misused than “arm” and “leg.” The most misused terms in musculoskeletal pathology are those related to disc lesions, and one commonly hears that a magnetic resonance image (MRI) scan was ordered “to rule out a disc,” but having a disc is neither an indication for MRI nor surgery. Further imprecise terminology leads to semantic imprecision when terminology is incorrectly used, including intervertebral disc, bulge, protrusion, extrusion, sequestered fragment, hernia, rupture, and even fracture . Physician evaluators and health care providers must understand that—by virtue of the authority vested in them and the weight given to their opinions by claims personnel, attorneys, judges, and others—errors and injustices may occur if they do not understand or correctly use medicolegal terms.

In order to answer questions posed by their clients, evaluating physicians must understand the context of a case or jurisdiction, in part because medical and legal perspectives may differ when an evaluator assesses issues such as causation and apportionment. A condition is not necessarily a ratable impairment, nor do symptomatic conditions necessarily prevent an individual from working. Attorneys may pose very specific apportionment questions based on laws unique to a given jurisdiction; for example, a patient may have an occupational injury or illness that results in impairment, but causation of the impairment may be multifactorial and may involve, for example, age-related degeneration, a pre-existing injury or illness, an occupational injury or illness, and/or subsequent trauma or disease. In some states, the presence of a pre-existing condition when an employee is injured may involve Second Injury Funds that were created to relieve a portion of the employer's/insurer's claim costs when the employer hired or retained an employee with a pre-existing medical condition who then suffered a “second” injury. The latter situation requires more extensive treatment and/or a greater disability due to the combined effects of both conditions. Apportionment of causation and impairment may be complex, requiring evaluation of nonoccupational and occupational risk factors and the natural history of the underlying condition.

In most cases of shoulder injury at work, causation analysis is not clear-cut and requires detailed, thoughtful, and time-consuming causation analysis; traditionally, physicians have approached this in a cursory manner, often presenting their findings as an opinion. An established method of causation analysis using six steps is outlined in the American College of Occupational and Environmental Medicine Guidelines and in the AMA Guides to the Evaluation of Disease and Injury Causation, Second Edition, as follows: 1) collect evidence of disease; 2) collect epidemiological data; 3) collect evidence of exposure; 4) collect other relevant factors; 5) evaluate the validity of the evidence; and 6) write a report with evaluation and conclusions. Evaluators also should recognize that thresholds for causation vary by state and are based on specific statutes or case law. Three cases illustrate evidence-based causation analysis using the six steps and illustrate how examiners can form well-founded opinions about whether a given condition is work related, nonoccupational, or some combination of these. An evaluator's causal conclusions should be rational, should be consistent with the facts of the individual case and medical literature, and should cite pertinent references. The opinion should be stated “to a reasonable degree of medical probability,” on a “more-probable-than-not” basis, or using a suitable phrase that meets the legal threshold in the applicable jurisdiction.

Repetitive illness sometimes is wrongly called repetitive injury or cumulative trauma, but the latter are misnomers because the employee cannot identify a specific injury as a cause of the symptoms. In workers’ compensation, such gradual illness claims may be compensable if the condition arises during the course of employment, which requires that it be caused by occupational duties, exposures, or equipment used on the employer's premises. Expert impairment evaluators face three requirements: they must know the best scientific evidence currently available regarding causation of the condition(s) in question, ie, generic causation; the facts of the individual case, ie, specific causation; and the legal threshold in the applicable jurisdiction for acceptance of a condition as work related. The AMA Guides to the Evaluation of Disease and Injury Causation, Second Edition, is an excellent resource and provides the physician a blueprint for the assessment of causation in occupational injury and illness claims. The book adopts the methodology developed by the National Institute for Occupational Safety and Health and the American College of Occupational and Environmental Medicine. When asked to render opinions regarding causation, a physician is wise to consider this methodology in determining the work relatedness of the condition. Medical opinions based on an accepted methodology and the best scientific evidence will result in better patient outcomes.

Causation analysis involves determining what conditions are related to a compensable injury or illness; apportionment is the allocation of responsibility among two or more probable causes; and assessing impairment is based on the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ). These three are separate activities, but sometimes all three must be addressed in a single evaluation and may be required for a specified jurisdiction (eg, California). Evaluators thus must ask if jurisdictional issues dictate or influence the approach to causation and apportionment; which edition of the AMA Guides to use; and how to approach causation and apportionment in the present case example: A 63-year-old woman with rheumatoid arthritis and systemic lupus erythematosus is assessed by an orthopedic surgeon who is the agreed medical evaluator (AME). In addition to her pre-existing rheumatoid arthritis and lupus, the individual also had Sjogren's syndrome, osteoarthritis, degenerative disc disease, left carpal tunnel syndrome, osteopenia, and obesity. She has undergone multiple surgical procedures, and treatment for her collagen vascular disease includes leflunomide (immunosuppressant), hydroxychloroquine, and prednisone. In this case, impairments were not the result of “cumulative trauma” but rather were secondary to underlying chronic inflammatory disease, and her occupational permanent impairment rating accordingly would be zero.

The normal cervical spine is straight in the coronal plane and usually is lordotic (curved convex anteriorly) in the sagittal plane, and although cervical spine deformity occurs in the coronal plane (eg, scoliosis), sagittal plane deformities are more common. For example, cervical lordosis can be increased (hyperlordosis) within the normal range, decreased (hypolordosis), absent (a straight cervical spine with 0° of curvature on a lateral X ray), or reversed (kyphosis). Primary deformity of the cervical spine often is congenital (eg, wedge vertebra); secondary sagittal deformities may be due to disc degeneration accompanying aging, disease such as ankylosing spondylitis, or surgery (eg, for postlaminectomy kyphosis). Decreased, straightened, or reversed cervical lordosis (DSRCL) may be idiopathic and can be voluntary, and evaluators must differentiate DSRCL that does not change over time vs sagittal plane alignment that varies over time or with a change in posture or position. DSRCL usually is asymptomatic, but severe cervical kyphosis can cause neck pain, myelopathy, dysphagia, loss of horizontal gaze, and other symptoms that are sufficiently severe to result in disability and to require surgical correction. Reports of DSRCL due to spasm, particularly at times temporally remote to an injury, should be met with extreme skepticism. Kyphosis of sufficient severity to be symptomatic usually is a postoperative deformity, not an effect of whiplash.

The AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ), Sixth Edition, introduced the concept of diagnosis-based impairments (DBI), and a modified version of this method can be used in rating peripheral nerve injury in general (Section 5.4) and upper limb entrapment syndromes (Section 15.4f). The first portion of this article reviews the evaluation of upper extremity nerve impairment and summarizes inclusion criteria and causation correlation for carpal tunnel syndrome, Guyon's canal syndrome, cubital tunnel syndrome, anterior interosseous, Wartenberg's syndrome, and radial tunnel syndrome. Very mild nerve entrapments do exist and may fail to meet the AMA Guides criteria for impairment related to a diagnosis of nerve entrapment. Electrodiagnostic examination includes nerve conduction studies that assess the largest, most heavily myelinated axons, and needle electromyelography, which detects muscle membrane instability but not the sensory function of nerves. A case example from the AMA Guides, Sixth Edition, shows the process of permanent impairment rating in a case of carpal tunnel syndrome. Determination of impairment for peripheral nerve entrapments can be easily accomplished once one understands how to determine if the nerve under consideration from the electrodiagnostic evaluation demonstrates a conduction delay, a conduction block, or an axon loss. This establishes the test findings that usually are the only objective findings present.