Medicolegal Assessment

17


Medicolegal Assessment




























Introduction 341 Whiplash: Acceleration Injury of the Cervical  
Disk Herniations and Accidents 342 Spine 346
Damage to the Intervertebral Disks After the Loss   Assessment of Loss of Earning Capacity in Lumbar  
or Permanent Injury of a Limb 345 Intervertebral Disk Disease 351

image Introduction


Frequency of Medicolegal Assessment of Disk-Related Diseases


Disk-related diseases have a high point prevalence as well as a high annual and lifetime prevalence and are, therefore, frequently the subject of medicolegal assessments by physicians. Indeed, they account for 60% of all such assessments, followed by disorders affecting the lower limbs (30%) and upper limbs (10%). Even when the primary damage is in a limb, e.g. after amputation or after stabilization of a joint, the affected individuals usually claim additional disability because of secondary effects on the spine. Disk disease commonly gives rise to claims of inability to work, inability to pursue one’s present occupation, and loss of earning capacity, as well as claims of occupational or accidental injury.


Problems


Pre-existing degenerative disease, the fluctuating nature of the clinical manifestations, and the lack of objective correlates to the pain all complicate the task of medicolegal assessment of disk disease. Because of the diversity of possible interpretations in this area, the judicial process is often protracted, and assessments are often met with counter-assessments and overriding assessments. A further difficulty arises from the fact that, with the exception of small children, all humans have some degree of degenerative disease of the intervertebral disks.



image The spine is much more commonly affected by pre-existing injury than any other part of the musculoskeletal system.


If a disk should be injured still further by a traumatic event, the medicolegal assessor must decide whether to lay more emphasis on the pre-existing injury or on the trauma. In all assessments, the fluctuating course of disk disease must be taken into account. The clinical picture varies not only in a circadian rhythm but also over the course of weeks, months, and years, complicating a fair evaluation. Individuals presenting for medicolegal assessment often have no symptoms on the day that they are examined. The physician must then refer to earlier reports in the medical record and to the patient’s description of the symptoms at other times. Imaging studies yield only a small amount of information in the medicolegal assessment of disk disease. On the other hand, an acute cervical or lumbar syndrome that is demonstrably present at the time of examination may subside within a few days or weeks. As discussed in Chapter 12, all types of disk disease tend to improve with age, which implies that all long-term judgments and assessments of diminished working capacity are subject to revision. Follow-up examinations are needed.


As in all other types of medicolegal assessment, attention must be paid to the patient’s own attitude to the disease manifestations that they describe. When there is a question of accidental or occupational injury, or indeed of injury while serving in the armed forces or as a consequence of persecution in another country, the most important issue is often that of etiology and pathogenesis. The affected individuals tend to attribute all their symptoms to the event in question. On the other hand, when the assessment concerns the inability to work or loss of earning capacity, causation is relatively unimportant and the main issue is the patient’s impaired ability to do their job and the corresponding classification in terms of loss of earning capacity (see Table 17.7). In medicolegal assessments concerning an individual’s ability to work or to participate in sports, one also finds a certain tendency toward malingering.



image Assessing the degree of disability caused by pre-existing spinal damage or trauma is just as difficult as evaluating the ability of individuals with an apparently normal spine to work or take part in sports.


image Disk Herniations and Accidents


Problems


Everyone who suffers from sudden-onset back pain attributes it to some external event, from a natural tendency to believe that everything must have a cause. Overexertion, faulty posture, or trauma is blamed for the pain. Questions of this type arise in all assessments of possible occupational or accidental injury, and the assessors’ opinions are varied. It is sometimes stated that the disks are actually quite robust and that trauma is more likely to fracture a vertebra than to rupture a disk, i.e., that all disk disease is a matter of biological destiny and attributable to degenerative change. Other assessors will attribute the entire disability in disk disease to one or more traumatic events, resulting in the official recognition of the problem as a traumatic injury.


Basic research, above all the studies of Krag (1987), Andersson (1991), Pope (1992), and Waddell (2004), has shown that external factors are part of the multifactorial causation of disk-related diseases and play a role in their etiology and pathogenesis, particularly with respect to the consequences of disk herniation. Individual traumatic events also have a degree of significance as part of this process.



image Degenerated disks are highly susceptible to external influences.


In medicolegal assessment, the main issue is in many cases a displacement of disk tissue—intradiscal displacement, protrusion, or prolapse—that may have been provoked or exacerbated by an accident. The assessment is complicated by the possibility that the changes seen in the plain radiographs, CT scans, and MRI scans obtained at the time of the accident might already have been present before the accident without causing any symptoms: 20% of all protrusions and prolapses are asymptomatic.


Pre-existing Damage


Because it can never be assumed that an adult patient had entirely healthy disks before an accident, the demand commonly made by insurance providers for proof of full bodily integrity before the event loses its relevance. No one over 30 years of age has a spine without degenerative changes rendering them more susceptible to external traumatic injury.


There is a particular susceptibility to such injury in midlife, when the biomechanical constellation favors displacement of disk tissue in the intervertebral space (see Chapter 12). Axial forces, particularly when combined with lateral bending and torsion, can bring about a decompensation of the tenuous state of the spine, with intradiscal tissue displacements, protrusions, and prolapses.


Although the structural changes are often impressive, the clinical findings are of primary importance for the assessment of pre-existing damage. Protrusions, prolapses, osteochondrosis, and spondylosis can be associated with only mild clinical manifestations, or none at all; on the other hand, there may be relatively marked symptoms when the structural changes are relatively slight. The physician trying to assess pre-existing damage due to degenerative disease must base any conclusions on the history obtained from the patient, and, especially in medicolegal situations, on the information contained in the medical record regarding any previous episodes or low back pain and/or sciatica requiring treatment. When classifying the pre-existing damage, the physician should take account of the fact that so-called simple back pain is a nearly universal condition that should not be designated as a pre-existing illness. Recurrent low back pain radiating into the leg and requiring medical treatment is of greater significance. Further evidence for the severity of earlier spinal problems can be derived from the very fact that radiological studies were obtained and special treatments such as paravertebral injections, hospitalizations, or surgery were undertaken, if this is the case. Any historical details that the patient cannot remember can be supplemented by information from previously treating physicians and insurance providers.


The Accident



image Definition: an accident, as defined by both private and statutory insurance providers, is a sudden, unpredictable external event that injures the body.


If the accidental event is of a dramatic nature, e.g., a fall, a blow, or a collision, then doubts are generally not expressed as to its having been an accident. Much less dramatic events are usually at issue as the possible cause of disk-related conditions. German law gives a very broad definition of the concept of an accident, particularly in the context of statutory accident insurance, and extends insurance protection not only to the effects of forces originating outside the body but also to a large number of other types of injury that can occur at work. Thus, slipping, twisting one’s ankle, stumbling, falling, and catching a heavy weight can all count as accidents. This problem is taken into account in the general conditions for private accident insurance. Insurance protection also extends to strains, sprains, and tears caused by unusually intense exertion on the part of the insured party. The precise course of the traumatic event determines whether it will be legally recognized as the cause of a disk syndrome. It must be determined whether the event described falls under the scope of the insurance policy. Activities that are normally part of the individual’s work and are associated with goal-directed movement initiated by the individual him/herself are not considered accidents; activities of this type include lifting and carrying a heavy load, working in a stooped posture, and pushing up a heavy load with the arms. “Faulty lifting,” i.e., an attack of pain during the lifting of a heavy object in a stooped posture, is the most common type of event requiring clarification in insurance law. This is a normal work activity that cannot be considered a traumatic event and is therefore outside the scope of accident insurance protection. Events of this type are consciously initiated by the individual him/herself. Any disk syndrome or disk herniation that might arise in the course of normal work activities would presumably have arisen at the same time, and with the same degree of intensity, if the individual had been involved in any other activity of everyday life instead.


Normal work activities can, however, be disturbed by external influences. If, in the course of a work activity, the individual must suddenly exert him/herself more than usual, with a sudden, involuntary (reflex) muscle contraction, or when an unusual type of movement is necessitated by an external influence, then this would satisfy the condition of a sudden, unpredictable external event required by the definition of an accident for the purposes of both private and statutory accident insurance.



image The essential feature of an accident is its unpredictability, i.e., being unforeseen and unavoidable.


The effects of such events on the mechanically labile intervertebral disk are much more marked than those of movements that are consciously executed as planned. Such situations arise, for example, when a worker stumbles while lifting and carrying, or when a carrying strap tears and the weight suddenly shifts. A traumatic event is also within the scope of accident insurance protection when, for example, several workers lift up a heavy object simultaneously and then, because the load tilts or one worker drops out, the entire load must suddenly be borne by a single individual. The high intradiscal pressures that come about during such an event, combined with torsion and undue stress on the lateral edge of the intervertebral disk, are produced before the individual has a chance to protect the disk with voluntary contraction of the truncal and proximal appendicular muscles.


 












Table 17.1 Requirements for a disk herniation or acute disk syndrome to be legally recognized as the result of an accident
 
 image There must be a sufficiently severe trauma, with high intradiscal pressure caused by a violent force originating outside the body and/or an unanticipated exertion that is unforeseen, unpredictable, and unavoidable.
 image The typical symptoms must arise immediately.
 image The patient must have been free of symptoms immediately before the event.

 


Criteria for Recognition

In addition to the presence of a sufficiently intense traumatic event, the state of the individual before and after the accident is of crucial importance in medicolegal assessment. The individual must be asymptomatic just before the event, i.e., the typical post-traumatic symptoms must not have been present immediately beforehand (Table 17.1). This question is usually resolved by noting that individuals with low back pain and sciatica generally do not expose themselves to additional mechanical loading of the type involved in the accident. Another important criterion for the recognition of a disk syndrome as being due to an accident is the immediate generation of symptoms. Symptoms that do not arise until hours or days after a given event, but are nonetheless causally attributed to it, should be regarded skeptically. Sudden intradiscal tissue displacements, protrusions, and prolapses cause severe pain immediately. Because the displaced disk tissue can also shift in position after the trauma, it is certainly possible for there to be low back pain immediately after the trauma that then develops into a radicular syndrome over the ensuing days because of further dorsolateral dislocation of the initially displaced tissue. The severe pain and limitation of movement usually cause the affected individual to cease working and present to medical attention within 24 h.


For individuals with the normal degree of pre-existing disk degeneration for their age who sustain a sufficiently intense trauma followed by an acute disk syndrome, the overall compensable injury is apportioned as follows over its further course, in the contexts of legally mandated and private accident insurance, respectively:


Statutory accident insurance. In Germany the principle of contributory causation applies, with all-or-nothing compensation. If the traumatic component predominates, then the overall compensable injury—i.e., the clinical syndrome of post-traumatic low back pain or sciatica—is to be viewed as being entirely the consequence of the accident, for a certain period of time. Only if the disease manifestations caused by the accident subside over time, to be replaced by other manifestations, can the latter be fully ascribed to pre-existing degenerative damage independent of the accident.


Manifestations caused by the accident can be distinguished from manifestations arising independently of it by reference to the spontaneous course of disk disease, as described in Chapter 12.


Private health insurance assumes that the patient’s problem, right from the beginning, has both a component that is caused by the accident and an accident-independent, degenerative component. The latter component is referred to as the contribution of events other than the accident. Depending on the extent of the problem that is attributed to accident-independent factors, the accident-related component may initially be assumed to account for up to 100% of the overall compensable injury and then be gradually scaled back over time. At a future time, the accident-related component might be assessed at, for example, 20 % for 1 year.


Permanent injury. Low back pain and sciatica normally subside over a few weeks to months, even when they are of traumatic origin. All further symptoms arising from the motion segment, particularly any new symptoms that might arise acutely, are a consequence of disk disease rather than of the accident.


If a disk herniation is recognized as being at least partly the result of an accident, then all types of permanent injury that might arise from it will also be the result of the accident, to the same extent as the original herniation. This applies, for example, to residual neurological deficits such as a foot drop after an L5 syndrome, a quadriceps paresis after an L3 or L4 syndrome, or symptoms due to postoperative adhesions (post-discotic syndrome) if the original disk herniation required surgery. Nonetheless, objectifiable permanent injuries, such as adverse sequelae of operations or neurological deficits after a post-traumatic disk syndrome, are encountered only rarely among all cases presenting for medicolegal assessment. In most cases, the expert carrying out the assessment has no evidence for a permanent injury beyond the patient’s subjective report of the course of illness. If it is stated that the pain subsided a certain time after the accident and then returned after an asymptomatic interval, then the expert will be able to divide the course of the illness into two periods—one in which the patient suffered from post-traumatic disk syndrome, and another in which the problem was due to degenerative disease.


Such statements by patients are rare. Much more commonly, it is claimed that the pain and impairment resulting from the accident have persisted without interruption from the day of the accident for months and years thereafter. In such cases, the assessment generally involves a stepwise reduction of the percentage of the overall compensable injury that can be attributed to the accident, in accordance with the general medical experience of the spontaneous resolution of disk disease. It can be safely assumed that the entire compensable injury cannot be attributed to the accident alone, because, if there had been no pre-existing damage, a situation of this severity would not have arisen in the first place.


The general medical experience of the spontaneous resolution of lumbar disk herniation (see Chapter 12) implies that the traumatically induced worsening of a disk syndrome undergoes a transition to the normal course of nontraumatic illness within 6 months to 1 year. No precise guidelines can be stated with regard to the percentage distribution of accident-induced and accident-independent factors over time. Any traumatically induced disk herniation that remains symptomatic afterward should be evaluated individually.


Summary


Disk disease is so common (in fact, universal) that the question is often raised whether a particular disk herniation was the result of an accident.


It can be assumed that every human has some degree of pre-existing disk damage (degeneration).


An accident is defined as an unforeseen traumatic event.


The prerequisites for the recognition of an accident as the cause of an intervertebral disk condition are a sufficiently intense trauma, an asymptomatic state before the accident, and typical symptoms immediately after it.


In the German system of statutory accident insurance, all manifestations of disk disease are recognized as being due to the accident, at least for a short period of time, as long as the three prerequisites listed above are satisfied. Private accident insurance, on the other hand, generally assumes a gradually decreasing percentage contribution of the accident to the causation of the overall compensable injury, with an increasing contribution of factors other than the accident.


The medical experience of the spontaneous course of acute disk syndromes implies that permanent damage is not to be expected, unless the disk herniation provoked by the accident has caused a demonstrable, permanent neurologic deficit or has been treated by surgery with consequent adverse sequelae.



Conclusion

Even though disk degeneration is a universal phenomenon in the absence of trauma, a disk herniation can still be legally recognized as the consequence of an accident if certain conditions are fulfilled.


image Damage to the Intervertebral Disks After the Loss or Permanent Injury of a Limb



image General considerations: The partial or total amputation of a limb has an effect on the spine. The motion segments, which normally bear a symmetrical load, are permanently asymmetrically loaded thereafter and develop abnormal signs of wear and tear. The loss or permanent injury of a limb is considered a “pre-discotic” condition, i.e., one that predisposes to the exacerbation of degenerative disk disease.


Cervical Spine


The loss or significant functional impairment of an upper limb induces an asymmetrical posture, particularly in the lower cervical motion segments. The healthy, functional limb is used preferentially; the cervical spine is laterally bent with the convexity on the side of the functional limb (so-called “idemscoliosis”). This abnormal posture, in time, leads to a fixed abnormal curvature of the spine with structural scoliosis. Symptoms arise through the overloading or abnormal loading of the shoulder and neck muscles and through the over-stretching or sprain of the intervertebral joint capsules of the cervical motion segments. On the concave side of the cervical spine, narrowing of the intervertebral foramina can produce signs of nerve root irritation.


Lumbar Spine


When an uncompensated leg-length discrepancy has been present for a long time, as after an amputation or severe knee injury (including fusion of the knee joint), a pelvic tilt develops, with a consequent lateral curve in the spine. The convexity usually points to the shorter, or damaged, side. The lateral curvature can be compensated for at first, but over time a structural scoliosis develops. Leg prostheses for amputees are usually fitted so as to be 1–2 cm shorter than the intact leg, to allow easier swinging of the prosthetic limb during walking, which is particularly useful if the ground is uneven.


Besides this static deviation in the frontal plane, prostheses with a containment socket for the ischial tuberosity also cause a change in the sagittal plane: the pelvis is tilted forward, with consequent hyperlordosis of the lumbar spine. Both of these static abnormalities, lateral curvature and hyperlordosis, are normally well compensated in younger patients, particularly those who actively participate in sports and gymnastics. When these compensatory mechanisms are no longer adequate, because of constitutional or age-related muscle insufficiency, the lumbar motion segments are put under excessive mechanical stress, particularly in the intervertebral joints. Decompensation is illustrated by a fixed lateral curvature of the lumbar spine on an AP plain radiograph, which should be supplemented by functional views in lateral bending to the left and the right. Such changes can also occur after long-standing unilateral functional impairment of a lower limb, resulting, e.g., from fusion of a knee, flexion contractures at the hip and knee joints, or deformities of the foot. The resulting limp places an asymmetrical stress on the spine, particularly the lower lumbar motion segments and the sacroiliac joints. The patient complains of spinal symptoms that arise mainly in the muscles and intervertebral joints. Back pain is most severe when the patient stands or walks. The symptoms are usually those of a local lumbar syndrome. Signs of nerve root irritation resulting from narrowing of the intervertebral foramina are relatively rare.


Medicolegal Assessment


Because of the high prevalence (point prevalence as well as annual and lifetime prevalence) of symptoms in the cervical and lumbar spine (see Chapter 3), amputees and individuals with a damaged limb on one side will often have such symptoms on a degenerative basis alone and then attribute them to their congenital or acquired impairment, simply because of our natural tendency to identify a specific cause for every effect.


There are no statistically valid data on whether amputees or individuals with a damaged limb on one side are more likely to suffer a disk protrusion or prolapse than a comparable control group of healthy individuals. The degree of lateral curvature of the spine, as seen in an AP plain radiograph, is a useful indicator of the severity of the spinal problem caused by a unilateral appendicular injury, and of the likelihood that it will be permanent. Functional radiographs with lateral bending to the right and left will demonstrate whether the curved deformity is “functional” (due to asymmetrical muscle contraction alone) or fixed (i.e., scoliosis, due to structural changes of the spine itself).


Unlike idiopathic constitutional scoliosis, lateral curvatures associated with amputation or severe damage to a limb are free of torsion, i.e., the spinous processes and the oval shadows of the roots of the laminae are projected normally (symmetrically) on plain radiographs. An exception to this rule is seen in permanent unilateral damage to a limb beginning in childhood; in such cases, the scoliosis induced by the injury always has a torsional component as well.


Degenerative changes of the cervical or lumbar spine that would have arisen even without any arm or leg injury must be taken into account as a contributory factor in assessments for private accident insurance and as a contributory cause of symptoms in assessments for statutory accident insurance. The more important changes of this type are loss of disk height in the lower segments of the cervical and lumbar spine and the accompanying local, sometimes radicular manifestations.


Summary


The extent of a unilateral upper or lower limb injury should be assessed. Measurements should be made of any tilting of the pelvis or lateral curvature of the spine, as seen in functional plain radiographs with maximal lateral bending to the right and left. The radiographs should also be inspected for signs of torsion.


If an injury-related lateral curvature of the cervical or lumbar spine is documented, the corresponding injury-related loss of loss of earning capacity should be no more than 10%.



Conclusion

Individuals with a demonstrable scoliosis as the consequence of the loss or permanent injury of a limb are considered to have a loss of earning capacity of up to 10 %.

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Mar 17, 2017 | Posted by in PHYSICAL MEDICINE & REHABILITATION | Comments Off on Medicolegal Assessment

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