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- Author or Editor: Charles N Brooks x
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Abstract
Injuries to a specific region can result in more than one diagnosis. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, states that, in most cases, only one diagnosis in a region (eg, hip, knee, or foot/ankle) is appropriate. If a patient has two significant diagnoses (eg, ankle instability and posterior tibial tendonitis), the examiner should use the diagnosis with the highest impairment rating in that region that is causally related. The rationale for this principle is that the rating for the diagnosis with the highest impairment also encompasses the functional loss of diagnoses with lesser impairment; it also attempts to prevent the use of multiple diagnoses to inflate the impairment rating. In the Case Example, a 62-year-old female teacher was tripped and fell on her left knee at work; the diagnoses were osteoarthritis and medial collateral ligament sprain. Despite activity modification and extensive treatment, she reported only moderate improvement; an orthopedic surgeon was consulted and recommended total knee replacement (TKR), but the patient declined and decided to retire with the option to consider TKR later, if necessary. Causation is an issue because tricompartmental arthritis clearly was not caused by the fall, but one wonders about the role of the individual's arthritis is unclear. Evaluators should be aware that such apportionment varies by jurisdiction.
Abstract
Multiple factors determine the likelihood, type, and severity of bodily injury following a motor vehicle collision and, in turn, influence the need for treatment, extent of disability, and likelihood of permanent impairment. Among the most important factors is the change in velocity due to an impact (Δv). Other factors include the individual's strength and elasticity, body position at the time of impact, awareness of the impending impact (ie, opportunity to brace, guard, or contract muscles before an impact), and effects of braking. Because Δv is the area under the acceleration vs time curve, it combines force and duration and is a useful way to quantify impact severity. The article includes a table showing the results of a literature review that concluded, “the consensus of human subject research conducted to date is that a single exposure to a rear-end impact with a Δv of 5 mph or less is unlikely to result in injury” in most healthy, restrained occupants. Because velocity incorporates direction as well as speed, a vehicular occupant is less likely to be injured in a rear impact than when struck from the side. Evaluators must consider multiple factors, including the occupant's pre-existing physical and psychosocial status, the mechanism and magnitude of the collision, and a variety of biomechanical variables. Recommendations based solely on patient history and physical findings (and, perhaps, imaging studies) may be ill-informed.
Abstract
Myelopathy literally indicates any pathology of the spinal cord, but the term most commonly is used when the cord pathology results from degenerative disease. Specific names usually are used if the disorder is traumatic (spinal cord injury), infectious (myelitis), or neoplastic (the name of the tumor is used). Cervical myelopathy (CM) may result in symptoms such as clumsiness, loss of dexterity, imbalance or poor coordination; muscle weakness; pain; and, in severe cases, bowel, bladder, or sexual dysfunction. When impairment is rated, if the evaluator finds objective evidence of myelopathy when the individual is at maximum medical improvement, neurological impairment is combined with that for the spine. A detailed and thorough neurologic examination is the current standard for the diagnosis of CM, but diagnosis is challenging in the early stages. Correlation of patient symptoms and imaging studies, both plain radiographs and magnetic resonance imaging scans, is essential for correct diagnosis. When imaging studies are equivocal or insensitive, other studies such as electrodiagnostic testing and cerebrospinal fluid analysis may be considered. When CM is defined as the presence of more than one long-tract sign, spinal cord compression in isolation did not cause myelopathy, and up to 20% of those with cord compression did not exhibit CM.
Abstract
Normal joint motions vary from one person to another and depend on multiple factors, which raises issues when evaluators attempt to address issues of causation and apportionment. Although the causation and apportionment of joint motion deficits were not addressed in the fourth and earlier editions of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), the fifth and sixth editions took three possibilities into consideration when they provided instructions about how to evaluate impairment due to diminished mobility of upper and lower limb joints. Evaluating physicians must consider whether: 1) the motion deficit existed before the injury or illness in question or if the deficit was caused by individual variation, aging, disease, trauma, and/or other cause; 2) the motion deficit was caused by the injury or illness that is at issue or is in question; and 3) a lesser, pre-existing motion deficit existed before the current injury or illness was aggravated (permanently increased). Because of variations in normal joint motions among individuals, examiners should measure the motions of the uninvolved as well as the involved joints, using the former to define normal. Any motion impairment of the uninvolved joint is subtracted from that for the involved joint to determine the net impairment. Examples from the fifth and sixth editions show applications of the AMA Guides to two sample cases.
Abstract
Meniscal tears and osteoarthritis (osteoarthrosis, degenerative arthritis, or degenerative joint disease) are two of the most common conditions involving the knee. This article includes definitions of apportionment and causes; presents a case report of initial and recurrent tears of the medial meniscus plus osteoarthritis (OA) in the medial compartment of the knee; and addresses questions regarding apportionment. The authors, experienced impairment raters who are knowledgeable regarding the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), show that, when instructions on impairment rating are incomplete, unclear, or inconsistent, interrater reliability diminishes (different physicians may derive different impairment estimates). Accurate apportionment of impairment is a demanding task that requires detailed knowledge of causation for the conditions in question; the mechanisms of injury or extent of exposures; prior and current symptoms, functional status, physical findings, and clinical study results; and use of the appropriate edition of the AMA Guides. Sometimes the available data are incomplete, requiring the rating physician to make assumptions. However, if those assumptions are reasonable and consistent with the medical literature and facts of the case, if the causation analysis is plausible, and if the examiner follows impairment rating instructions in the AMA Guides (or at least uses a rational and hence defensible method when instructions are suboptimal), the resulting apportionment should be credible.
Abstract
Acromioclavicular joint (ACJ) arthritis is a common source of shoulder pain. Manifestations of the arthritis may include inferiorly projecting spurs that predispose an individual to impingement and rotator cuff tears and can result in permanent impairment due to shoulder weakness or motion loss. Rotator cuff tendinopathy generally is multifactorial, and tears usually result from a combination of intrinsic factors (loads transmitted, local blood supply, and age) and extrinsic factors (impingement, primarily). Surgery to eliminate impingement collectively is termed subacromial decompression. The AMA Guides to the Evaluation of Permanent Impairment provides no impairment rating for cheilectomy about acromioclavicular or other joints, and, because removal of this liability is beneficial, it results in no (and perhaps even negative) impairment. An individual whose job involves repetitive shoulder elevation and who develops impingement probably has a legitimate workers’ compensation claim, even if predisposed by preexisting bony prominences; in this scenario, the proximate cause was repetitive shoulder elevation. A case example demonstrates that if an individual with preexisting osteoarthritis of the ACJ is injured and disabled at work, the rotator cuff tear, although preexisting, was worsened during employment and probably will be covered under the claim. In legal terms, findings of disability associated with ACJ injuries may differ depending on the jurisdiction.
Abstract
Most acute injuries and illnesses resolve, ie, reach maximum medical improvement (MMI), within days or weeks and without permanent impairment. Fractures, more severe soft tissue injuries and illness, and conditions that require surgery take longer to reach MMI, often about a year, with a range of six months to two years. Serious head, spinal cord, and other catastrophic injuries commonly take two or more years to reach MMI. These more severe injuries and illnesses understandably are more likely to result in permanent impairment. However, various parties to the claim process may request impairment rating prematurely: The claimant or plaintiff whose injury or illness has resulted in loss of income and financial hardship may push for an early impairment award or settlement. The surgeon who has operated and is done with postoperative follow-up may want to be rid of claim forms and move on to other patients. The overburdened adjuster may want to get the claim closed, thereby diminishing their workload. But rating impairment prior to MMI, ie, before it is permanent, often results in erroneously inflated ratings. In general, functional status, physical findings, and/or clinical study results improve over time, sometimes with and sometimes without treatment. This usually results in a concurrent decrease in, and sometimes even resolution of, impairment. With knowledge of the appropriate terminology and definitions, the evaluating physician should be able to render an opinion regarding MMI that is both understandable and legally sustainable in the applicable jurisdiction.
Abstract
Chapter 16, The Upper Extremities, in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, presents several changes from the Fourth Edition. The changes are minor compared to those in Chapter 15, The Spine, but are more significant than those in Chapter 17, The Lower Extremities. This article examines some of the most important revisions, notably the more rigorous standards for upper extremity evaluation, the requirement to compare motion findings to those of the contralateral extremity, entrapment neuropathies evaluation, and strength assessment. The principles of assessment are essentially unchanged in the AMA Guides, Fifth Edition, and Section 16.1c now clarifies the process of combining assessments. The Fifth Edition provides more direction about how to measure motion, but the values for motion deficits remain the same as in the Fourth Edition. Among important changes in the Fifth Edition regarding rating peripheral nerve impairment are: grading sensory deficits, rating entrapment neuropathies, and evaluating complex regional pain syndrome. The most noteworthy changes in assessing impairment due to other disorders are the following: explicit directions about how to rate these other disorders; elimination of rating for joint crepitation; inclusion of new radiographic criteria for rating carpal instability, and introduction of a new process for rating shoulder instability. The discussion of strength is expanded in the Fifth Edition of the AMA Guides.
