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Abstract
Total ankle replacement (TAR), also known as total ankle arthroplasty, has been used since the early 1970s, but, because of improvements in both techniques and materials, the procedure is used more frequently, and examiners are asked to rate permanent impairment resulting from TAR. The AMA Guides to the Evaluation of Permanent Impairment, (AMA Guides) is silent about rating ankle impairment following arthroplasty but does provide a two-step method to rate the results of total hip and knee replacements. Using tables in the AMA Guides, examiners can rate disability associated with TAR. To provide a standard method for reporting the clinical status of the ankle and foot, the American Orthopaedic Foot and Ankle Society (AOFAS) published rating scales for four anatomic regions, one of which (the ankle-hindfoot scale), can be used to rate the clinical status of ankle, subtalar, talonavicular, and calcaneocuboid joints before and after treatment. The AOFAS scale includes neither patient satisfaction nor many other functional, physical, and radiographic findings, and the AOFAS ankle-hindfoot scale is not and never was intended to be comprehensive. Examiners can follow the same procedures for rating hip and knee replacements, substituting the AOFAS scale for rating clinical outcomes. [Two Quick References in this issue of The Guides Newsletter provide tables and figures relevant to rating upper extremity sensory and motor deficits and to measuring impairments of the hand and digits.]
Abstract
The three components of electrodiagnosis useful in evaluation of the peripheral nervous system and spinal cord include electromyography (EMG), electroneurography (nerve conduction studies), and somatosensory evoked potentials. EMG examination involves introduction of a special recording needle into a muscle belly. Electrical potentials located within a few millimeters of the needle are picked up by an electrode and are transmitted from the muscle to amplifiers that filter and display results visually for the electromyographer. Three types of spontaneous activity in electrical potentials are of the greatest relevance: positive sharp waves, fibrillation potentials, and fasciculations (fasciculation potentials on the EMG result from irregular firing of motor units). Electromyography can help assess the status of nerve fibers indirectly, but the integrity of large myelinated sensory and motor neurons can be evaluated directly by nerve conduction studies (NCS), also known as electroneurography. NCS can assess motor neurons, sensory neurons, or mixed nerve trunks. Sensory nerve conduction velocity can be studied in a manner analogous to motor conduction velocity: sensory fibers can be directly stimulated, and the evoked response can be measured at the wrist and elbow. Somatosensory evoked potentials occasionally are useful as an adjunct to EMG and NCS in the diagnosis of peripheral nervous system pathology. These tests also are useful when it is unclear whether an individual has a true radiculopathy.
Abstract
The term maximum medical improvement (MMI) is important to understand because an evaluator cannot determine permanent impairment until a condition is permanent and stationary. In addition, in many jurisdictions MMI represents the date beyond which at least some benefits cease or when an impairment award is made or a pension is awarded. Before rendering an opinion, the evaluating physician should become familiar with the terminology used and the definitions in the applicable federal, state, or provincial law or insurance policy. The AMA Guides to the Evaluation of Permanent Impairment does not define MMI but does state 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. Certain principles are common to definitions of MMI and its synonyms. A generic definition could be: “Maximum medical improvement is when further treatment will probably not result in significant, sustained improvement in the symptoms or signs of an injury or illness, or an individual's physical or mental capacities.” The signs may be physical, radiographic, laboratory, electrodiagnostic, or other findings, and the definition implies that the condition is medically stable in the sense that further treatment probably will not result in appreciable, prolonged improvement.
Abstract
Acromioplasty can be performed open or arthroscopically and removes the spurred, curved, or hooked portion of the acromion. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) has not addressed whether acromioplasty itself constitutes an impairment. On the one hand, if impairment is defined as “a loss, loss of use, or derangement of any body part, organ system, or organ function,” then acromioplasty is an impairment because of the loss of a small portion of the scapula. On the other hand, acromioplasty generally results in improved function (ie, no or negative impairment) and may increase rather than decrease an individual's ability to perform the activities of daily living. This does not indicate that patients who undergo acromioplasty have no impairment whatsoever, and remaining motion deficits should be rated according to existing criteria in the AMA Guides. For example, failure to properly reattach the deltoid muscle or excessive acromial resection may result in deltoid weakness or strength. Often during acromioplasty, the removal of the clavicular spur is accomplished via excision of distal clavicle (resection arthroplasty), which is a permanent impairment. Acromionectomy, which is functionally similar to distal clavicular resection, and transposing the 10% upper extremity impairment rating for distal clavicular resection to a total acromionectomy appears to be justified.
Abstract
Previous issues of The Guides Newsletter have presented overviews of electrodiagnostic evaluation, including electromyography, nerve conduction studies, and somatosensory-evoked responses. This article contains suggestions for nonelectromyographers who read reports and identify questionable uses of electrodiagnosis, specifically for the evaluation of radiculopathy and focal neuropathy (eg, nerve entrapments), the two most common presentations. Some subtle abnormalities (eg, changes in motor unit recruitment pattern, changes in firing rate, or reduction in motor units recruited) often are overinterpreted by poorly trained or inexperienced electromyographers. Nerve conduction studies often are overused and may accompany the electromyogram without apparent indication, but they are nearly useless in diagnosing radiculopathy and should be included only for nerve entrapment or differential diagnosis of plexus injury. Nerve conduction studies often are accompanied by F waves and H reflexes. The F wave helps assess proximal portions of nerves and is used primarily in the diagnosis of Landry-Guillain-Barré syndrome but has poor sensitivity and specificity in evaluation of radiculopathy or entrapment neuropathy. The H reflex is used primarily in S1 radiculopathy evaluation. The article includes six questions a clinician should bear in mind while interpreting the electrodiagnostic report. Improperly trained physicians may report false positive or negative results, so examiners should be aware of the qualifications of physicians to whom they refer their patients.
Abstract
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.
Abstract
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.
Abstract
Accurate measurement of hip motion is important in initial diagnosis, assessing progression over time, evaluating treatment outcomes, and rating impairments of this joint. In the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, range-of-motion (ROM) measurements are still a factor because the physical examination and other adjustment tables are used to select the grade and final rating. Further, ROM deficits may be used to derive a stand-alone rating when other tables refer the rater to motion impairment or if no diagnosis-based section is applicable for impairment rating. Hip motions generally are measured using a large goniometer, although an electronic inclinometer also may be used. Examiners must conduct tests in accordance with measurement instructions in the AMA Guides. From the standpoint of impairment rating, hip extension, at least beyond neutral, is irrelevant; if a patient does not have a flexion contracture of at least 10°, there is no extension impairment. Examiners should compare both extremities; active or voluntary motion is performed by the active contraction of the governing muscles and should be evaluated first. During this and other measurements, patients may have a tendency to extend or guard, thus producing an erroneously inflated measurement. Examiners must ensure that such behaviors do not occur and should record only the correct measurement.
Abstract
Because of their education and training, treating physicians often address causality only in terms of differential diagnosis (ie, what is causing the individual's symptoms and signs). Etiology also can be considered from a prophylactic or therapeutic standpoint (ie, how to prevent recurrent injury or eliminate the cause of an illness). In workers’ compensation, causation analysis extends beyond diagnosis, prophylaxis, and treatment and must consider whether the condition is attributable to the workplace. The terms cause, effect, exacerbation, and aggravation have specific meanings in the AMA Guides to the Evaluation of Permanent Impairment and are defined, with discussion. Three criteria must be met before causation is established in workers’ compensation: the cause is medically probable; the effect is medically probable; and the cause and effect probably are etiologically related (ie, the occupational trauma likely caused the injury, or the exposure caused the illness). A table presents the steps in a causation analysis in workers’ compensation: 1) define the injury, activity, or exposure (cause); 2) establish the diagnosis; 3) determine generic causation; specifically, determine if the reported mechanism, activity, or exposure ever causes the patient injury or disease; 4) determine specific causation in this instance and determine if another (more probably) nonoccupational cause was involved.
