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Workers compensation guidelines for the evaluation of permanent impairment

Foreword

The State Insurance Regulatory Authority has issued the 4th edition of the NSW workers compensation guidelines for the evaluation of permanent impairment for assessing the degree of permanent impairment arising from an injury or disease within the context of workers’ compensation. When a person sustains a permanent impairment, trained medical assessors m```ust use the Guidelines to ensure an objective, fair and consistent method of evaluating the degree of permanent impairment.

The Guidelines are based on a template that was developed through a national process facilitated by Safe Work Australia. They were initially developed for use in the NSW system and incorporate numerous improvements identified by the then WorkCover NSW Whole Person Impairment Coordinating Committee over 13 years of continuous use. Members of this committee and of the South Australia Permanent Impairment Committee (see list in Appendix 2) dedicated many hours to thoughtfully reviewing and improving the Guidelines. This work is acknowledged and greatly appreciated.

The methodology in the Guidelines is largely based on the American Medical Association’s Guides to the Evaluation of Permanent Impairment, 5th Edition (AMA5). The AMA guides are the most authoritative and widely used in evaluating permanent impairment around the world. Australian medical specialists representing Australian medical associations and colleges have extensively reviewed AMA5 to ensure it aligns with clinical practice in Australia.

The Guidelines consist of an introductory chapter followed by chapters dedicated to each body system.

The Introduction is divided into three parts. The first outlines the background and development of the Guidelines, including reference to the relevant legislative instrument that gives effect to the Guidelines. The second covers general assessment principles for medical practitioners applying the Guidelines in assessing permanent impairment resulting from work-related injury or disease. The third addresses administrative issues relating to the use of the Guidelines.

As the template national guideline has been progressively adapted from the NSW Guideline and is to be adopted by other jurisdictions, some aspects have been necessarily modified and generalised. Some provisions may differ between different jurisdictions. For further information, please see the Comparison of Workers’ Compensation Arrangements in Australia and New Zealand report, which is available on Safe Work Australia’s website.

Publications such as this only remain useful to the extent that they meet the needs of users and those who sustain a permanent impairment. It is, therefore, important that the protocols set out in the Guidelines are applied consistently and methodically. Any difficulties or anomalies need to be addressed through modification of the publication and not by idiosyncratic reinterpretation of any part. All queries on the Guidelines or suggestions for improvement should be addressed to the State Insurance Regulatory Authority at contact@sira.nsw.gov.au.

Introduction

Part 1 - Intent and legislation basis for these guidelines.

For the purposes of the WorkCover Authority of NSW*, the 4th edition of the NSW workers compensation guidelines for the evaluation of permanent impairment (the Guidelines) are made under s376 of the Workplace Injury Management and Workers Compensation Act 1998 (WIMWC Act). The Guidelines are to be used within the NSW workers compensation system to evaluate permanent impairment arising from work-related injuries and diseases.

The Guidelines adopt the 5th edition of the American Medical Association’s Guides to the Evaluation of Permanent Impairment (AMA5) in most cases. Where there is any deviation, the difference is defined in the Guidelines and the procedures detailed in each section are to prevail.

Date of effect

The Guidelines replace the WorkCover Guides for the evaluation of permanent impairment, 3rd edition, which was issued in February 2009, and apply to assessments of permanent impairment conducted on or after 1 April 2016.

When conducting a permanent impairment assessment in accordance with the Guidelines, assessors are required to use the version current at the time of the assessment.

Development of the Guidelines

The Guidelines are based on a template that was developed through a national process facilitated by Safe Work Australia. The template national guideline is based on similar guidelines developed and used extensively in the NSW workers compensation system. Consequently, provisions in the Guidelines are the result of extensive and in-depth deliberations by groups of medical specialists convened to review AMA5 in the Australian workers compensation context. In NSW it is a requirement under s377(2) of the WIMWC Act that the guidelines are developed in consultation with relevant medical colleges. The groups that contributed to the development of the Guidelines is acknowledged and recorded at Appendix 2. The template national guideline has been adopted for use in multiple Australian jurisdictions.

Use of the Guidelines is monitored by the jurisdictions that have adopted it. The Guidelines may be reviewed if significant anomalies or insurmountable difficulties in their use become apparent.

The Guidelines are intended to assist a suitably qualified and experienced medical practitioner in assessing a claimant’s degree of permanent impairment.

Part 2 - Principles of assessment

The following is a basic summary of some key principles of permanent impairment assessments:

  • Assessing permanent impairment involves clinical assessment of the claimant as they present on the day of assessment taking account the claimant’s relevant medical history and all available relevant medical information to determine: whether the condition has reached Maximum Medical Improvement (MMI)
    • whether the claimant’s compensable injury/condition has resulted in an impairment
    • whether the resultant impairment is permanent
    • the degree of permanent impairment that results from the injury
    • the proportion of permanent impairment due to any previous injury, pre-existing condition or abnormality, if any, in accordance with diagnostic and other objective criteria as outlined in these Guidelines.
  • Assessors are required to exercise their clinical judgement in determining a diagnosis when assessing permanent impairment and making deductions for pre-existing injuries/conditions.
  • In calculating the final level of impairment, the assessor needs to clarify the degree of impairment that results from the compensable injury/condition. Any deductions for pre-existing injuries/conditions are to be clearly identified in the report and calculated. If, in an unusual situation, a related injury/condition has not previously been identified, an assessor should record the nature of any previously unidentified injury/ condition in their report and specify the causal connection to the relevant compensable injury or medical condition.
  • The referral for an assessment of permanent impairment is to make clear to the assessor the injury or medical condition for which an assessment is sought – see Information required for assessments in the Guidelines.

* As of 1 September 2015, the workers compensation insurance regulatory functions of WorkCover NSW have been assumed by the State Insurance Regulatory Authority.

Medical assessors are expected to be familiar with chapters 1 and 2 of AMA5, in addition to the information in this introduction.

The degree of permanent impairment that results from the injury/condition must be determined using the tables, graphs and methodology given in the Guidelines and the AMA5, where appropriate.

The Guidelines may specify more than one method that assessors can use to establish the degree of a claimant’s permanent impairment. In that case, assessors should use the method that yields the highest degree of permanent impairment. (This does not apply to gait derangement – see The approach to assessment of the lower extremity and Gait derangement in the Guidelines).

Body systems covered by the Guidelines

AMA5 is used for most body systems, with the exception of psychiatric and psychological disorders, chronic pain, and visual and hearing injuries.

AMA5 Chapter 14, on mental and behavioural disorders, has been omitted. The Guidelines contain a substitute chapter on the assessment of psychiatric and psychological disorders which was written by a group of Australian psychiatrists.

AMA5 Chapter 18, on pain, is excluded entirely at the present time. Conditions associated with chronic pain should be assessed on the basis of the underlying diagnosed condition, and not on the basis of the chronic pain. Where pain is commonly associated with a condition, an allowance is made in the degree of impairment assigned in the Guidelines. Complex regional pain syndrome should be assessed in accordance with Evaluation of permanent impairment arising from chronic pain in the Guidelines.

On the advice of medical specialists (ophthalmologists), assessments of visual injuries are conducted according to the American Medical Association’s Guides to the Evaluation of Permanent Impairment, 4th Edition (AMA4).

The methodology for evaluating permanent impairment due to hearing loss is in Hearing Loss of the Guidelines, with some reference to AMA5 Chapter 11 (pp 245–251) and also the tables in the National Acoustic Laboratories (NAL) Report No. 118, Improved Procedure for Determining Percentage Loss of Hearing, January 1988.

Maximum medical improvement

Assessments are only to be conducted when the medical assessor considers that the degree of permanent impairment of the claimant is unlikely to improve further and has attained maximum medical improvement. This is considered to occur when the worker’s condition is well stabilised and is unlikely to change substantially in the next year with or without medical treatment.

If the medical assessor considers that the claimant’s treatment has been inadequate and maximum medical improvement has not been achieved, the assessment should be deferred and comment made on the value of additional or different treatment and/or rehabilitation – subject to section Refusal of treatment in the Guidelines.

Multiple impairments

Impairments arising from the same injury are to be assessed together. Impairments resulting from more than one injury arising out of the same incident are to be assessed together to calculate the degree of permanent impairment of the claimant.

The Combined Values Chart in AMA5 (pp 604–06) is used to derive a percentage of whole person impairment (WPI) that arises from multiple impairments. An explanation of the chart’s use is found on pp 9–10 of AMA5. When combining more than two impairments, the assessor should commence with the highest impairment and combine with the next highest and so on.

The exception to this rule is in the case of psychiatric or psychological injuries. Where applicable, impairments arising from primary psychological and psychiatric injuries are to be assessed separately from the degree of impairment that results from any physical injuries arising out of the same incident. The results of the two assessments cannot be combined.

In the case of a complex injury, where different medical assessors are required to assess different body systems, a ‘lead assessor’ should be nominated to coordinate and calculate the final degree of permanent impairment as a percentage of WPI resulting from the individual assessments.

Psychiatric and psychological injuries

Psychiatric and psychological injuries in the NSW workers compensation system are defined as primary psychological and psychiatric injuries in which work was found to be a substantial contributing factor.

A primary psychiatric condition is distinguished from a secondary psychiatric or psychological condition, which arises as a consequence of, or secondary to, another work related condition (eg depression associated with a back injury). No permanent impairment assessment is to be made of secondary psychiatric and psychological impairments. As referenced in section Multiple impairments, impairments arising from primary psychological and psychiatric injuries are to be assessed separately from the degree of impairment that results from physical injuries arising out of the same incident. The results of the two assessments cannot be combined.

Conditions that are not covered in the Guidelines – equivalent or analogous conditions

AMA5 (p 11) states:

‘Given the range, evolution and discovery of new medical conditions, these Guidelines cannot provide an impairment rating for all impairments… In situations where impairment ratings are not provided, these Guidelines suggest that medical practitioners use clinical judgment, comparing measurable impairment resulting from the unlisted condition to measurable impairment resulting from similar conditions with similar impairment of function in performing activities of daily living.’ The assessor must stay within the body part/region when using analogy. ‘The assessor’s judgment, based upon experience, training, skill, thoroughness in clinical evaluation, and ability to apply the Guidelines criteria as intended, will enable an appropriate and reproducible assessment to be made of clinical impairment.’

Activities of daily living

Many tables in AMA5 (eg in the spine section) give class values for particular impairments, with a range of possible impairment values in each class. Commonly, the tables require the assessor to consider the impact of the injury or illness on activities of daily living (ADL) in determining the precise impairment value. The ADL which should be considered, if relevant, are listed in AMA5 Table 1–2 (p 4). The impact of the injury on ADL is not considered in assessments of the upper or lower extremities.

The assessment of the impact of the injury or condition on ADL should be verified, wherever possible, by reference to objective assessments – for example, physiotherapist or occupational therapist functional assessments and other medical reports.

Rounding

Occasionally the methods of the Guidelines will result in an impairment value which is not a whole number (eg an assessment of peripheral nerve impairment in the upper extremity). All such values must be rounded to the nearest whole number before moving from one degree of impairment to the next (eg from finger impairment to hand impairment, or from hand impairment to upper extremity impairment) or from a regional impairment to a WPI. Figures should also be rounded before using the combination tables. This will ensure that the final WPI will always be a whole number. The usual mathematical convention is followed where rounding occurs – values less than 0.5 are rounded down to the nearest whole number and values of 0.5 and above are rounded up to the next whole number. The method of calculating levels of binaural hearing loss is shown in section Hearing impairment, in the Guidelines.

Deductions for pre-existing condition or injuries

The degree of permanent impairment resulting from pre-existing impairments should not be included in the final calculation of permanent impairment if those impairments are not related to the compensable injury. The assessor needs to take account of all available evidence to calculate the degree of permanent impairment that pre-existed the injury.

In assessing the degree of permanent impairment resulting from the compensable injury/condition, the assessor is to indicate the degree of impairment due to any previous injury, pre-existing condition or abnormality. This proportion is known as ‘the deductible proportion’ and should be deducted from the degree of permanent impairment determined by the assessor. For the injury being assessed, the deduction is 1/10th of the assessed impairment, unless that is at odds with the available evidence.

Adjustment for the effects of orthoses and prostheses

Assessments of permanent impairment are to be conducted without assistive devices, except where these cannot be removed. The assessor will need to make an estimate as to what is the degree of impairment without such a device, if it cannot be removed for examination purposes. Further details may be obtained in the relevant sections of the Guidelines.

Impairment of vision should be measured with the claimant wearing their prescribed corrective spectacles and/or contact lenses, if this was usual for them before the injury. If, as a result of the injury, the claimant has been prescribed corrective spectacles and/or contact lenses for the first time, or different spectacles and/or contact lenses than those prescribed pre-injury, the difference should be accounted for in the assessment of permanent impairment.

Adjustment for the effects of treatment

In circumstances where the treatment of a condition leads to a further, secondary impairment, other than a secondary psychological impairment, the assessor should use the appropriate parts of the Guidelines to evaluate the effects of treatment, and use the Combined Values Chart (AMA5, pp 604–06) to arrive at a final percentage of WPI.

Where the effective long-term treatment of an illness or injury results in apparent substantial or total elimination of the claimant’s permanent impairment, but the claimant is likely to revert to the original degree of impairment if treatment is withdrawn, the assessor may increase the percentage of WPI by 1%, 2% or 3%. This percentage should be combined with any other impairment percentage, using the Combined Values Chart. This paragraph does not apply to the use of analgesics or anti-inflammatory medication for pain relief.

Where a claimant has declined treatment which the assessor believes would be beneficial, the impairment rating should be neither increased nor decreased – see paragraph 1.35 for further details.

Refusal of treatment

If the claimant has been offered, but has refused, additional or alternative medical treatment that the assessor considers likely to improve the claimant’s condition, the medical assessor should evaluate the current condition without consideration of potential changes associated with the proposed treatment. The assessor may note the potential for improvement in the claimant’s condition in the evaluation report, and the reasons for refusal by the claimant, but should not adjust the level of impairment on the basis of the claimant’s decision.

Future deterioration of a condition

Similarly, if a medical assessor forms the opinion that the claimant’s condition is stable for the next year, but that it may deteriorate in the long term, the assessor should make no allowance for this deterioration.

Inconsistent presentation

AMA5 (p 19) states:

‘Consistency tests are designed to ensure reproducibility and greater accuracy. These measurements, such as one that checks the individual’s range of motion are good but imperfect indicators of people’s efforts. The assessor must use their entire range of clinical skill and judgment when assessing whether or not the measurements or test results are plausible and consistent with the impairment being evaluated. If, in spite of an observation or test result, the medical evidence appears insufficient to verify that an impairment of a certain magnitude exists, the assessor may modify the impairment rating accordingly and then describe and explain the reason for the modification in writing.’

This paragraph applies to inconsistent presentation only.

Ordering of additional investigations

As a general principle, the assessor should not order additional radiographic or other investigations purely for the purpose of conducting an assessment of permanent impairment.

However, if the investigations previously undertaken are not as required by the Guidelines, or are inadequate for a proper assessment to be made, the medical assessor should consider the value of proceeding with the evaluation of permanent impairment without adequate investigations.

In circumstances where the assessor considers that further investigation is essential for a comprehensive evaluation to be undertaken, and deferral of the evaluation would considerably inconvenience the claimant (eg when the claimant has travelled from a country region specifically for the assessment), the assessor may proceed to order the appropriate investigations provided that there is no undue risk to the claimant. The approval of the referring body for the additional investigation will be required to ensure that the costs of the test are met promptly.

Part 3 - Administrative process

Medical assessors

An assessor will be a registered medical practitioner recognised as a medical specialist.

‘Medical practitioner’ means a person registered in the medical profession under the Health Practitioner Regulation National Law (NSW) No. 86a, or equivalent Health Practitioner Regulation National Law in their jurisdiction with the Australian Health Practitioner Regulation Agency.

‘Medical specialist’ means a medical practitioner recognised as a specialist in accordance with the Health Insurance Regulations 1975, Schedule 4, Part 1, who is remunerated at specialist rates under Medicare.

The assessor will have qualifications, training and experience relevant to the body system being assessed. The assessor will have successfully completed requisite training in using the Guidelines for each body system they intend on assessing. They will be listed as a trained assessor of permanent impairment for each relevant body system(s) on the State Insurance Regulatory Authority website.

An assessor may be one of the claimant’s treating practitioners or an assessor engaged to conduct an assessment for the purposes of determining the degree of permanent impairment.

Information required for assessments

Information for claimants regarding independent medical examinations and assessments of permanent impairment should be supplied by the referring body when advising of the appointment details.

On referral, the medical assessor should be provided with all relevant medical and allied health information, including results of all clinical investigations related to the injury/condition in question.

Most importantly, assessors must have available to them all information about the onset, subsequent treatment, relevant diagnostic tests, and functional assessments of the person claiming a permanent impairment. The absence of required information could result in an assessment being discontinued or deferred. AMA5 Chapter 1, Section 1.5 (p 10) applies to the conduct of assessments and expands on this concept.

The Guidelines and AMA5 indicate the information and investigations required to arrive at a diagnosis and to measure permanent impairment. Assessors must apply the approach outlined in the Guidelines.

Referrers must consult this publication to gain an understanding of the information that should be provided to the assessor in order to conduct a comprehensive evaluation of impairment.

Reports

A report of the evaluation of permanent impairment should be accurate, comprehensive and fair. It should clearly address the question(s) being asked of the assessor. In general, the assessor will be requested to address issues of:

  • current clinical status, including the basis for determining maximum medical improvement
  • the degree of permanent impairment that results from the injury/condition, and
  • the proportion of permanent impairment due to any previous injury, pre-existing condition or abnormality, if applicable.

The report should contain factual information based on all available medical information and results of investigations, the assessor’s own history-taking and clinical examination. The other reports or investigations that are relied upon in arriving at an opinion should be appropriately referenced in the assessor’s report.

As the Guidelines are to be used to assess permanent impairment, the report of the evaluation should provide a rationale consistent with the methodology and content of the Guidelines. It should include a comparison of the key findings of the evaluation with the impairment criteria in the Guidelines. If the evaluation was conducted in the absence of any pertinent data or information, the assessor should indicate how the impairment rating was determined with limited data.

The assessed degree of impairment is to be expressed as a percentage of WPI.

The report should include a conclusion of the assessor, including the final percentage of WPI. This is to be included as the final paragraph in the body of the report, and not as a separate report or appendix. The report must include a copy of all calculations and a summary table. A template reporting format is provided in the WorkCover Guidelines on independent medical examinations and reports.

Reports are to be provided within 10 working days of the assessment being completed, or as agreed between the referrer and the assessor.

Quality assurance

The degree of permanent impairment that results from the injury must be determined using the tables, graphs and methodology given in the Guidelines, as presented in the training in the use of the Guidelines and the applicable legislation. If it is not clear that a report has been completed in accordance with the Guidelines, clarification may be sought from the assessor who prepared the report.

An assessor who is identified as frequently providing reports that are not in accord with the Guidelines, or not complying with other service standards as set by the State Insurance Regulatory Authority, may be subject to State Insurance Regulatory Authority performance monitoring procedures and be asked to show cause as to why their name should not be removed from the list of trained assessors on the State Insurance Regulatory Authority website.

Code of conduct

Assessors are referred to the Medical Board of Australia’s Good Medical Practice: A Code of Conduct for Doctors in Australia, 8.7 Medico-legal, insurance and other assessments.

Assessors are reminded that they have an obligation to act in an ethical, professional and considerate manner when examining a claimant for the determination of permanent impairment.

Effective communication is vital to ensure that the claimant is well informed and able to maximally cooperate in the process. Assessors should:

  • ensure that the claimant understands who the assessor is and the assessor’s role in the evaluation
  • ensure that the claimant understands how the evaluation will proceed
  • take reasonable steps to preserve the privacy and modesty of the claimant during the evaluation
  • not provide any opinion to the claimant about their claim.

Complaints received in relation to the behaviour of an assessor during an evaluation will be managed in accordance with the process outlined in the WorkCover Guidelines on independent medical examinations and reports the and State Insurance Regulatory Authority website and performance monitoring procedures.

Disputes over the assessed degree of permanent impairment

Where there is a discrepancy or inconsistency between medical reports that cannot be resolved between the parties, the Workers Compensation Commission has the jurisdiction to determine disputes about assessed degree of permanent impairment.10 STATE INSURANCE REGULATORY AUTHORITY

Upper extremity

AMA5 Chapter 16 (p 433) applies to the assessment of permanent impairment of the upper extremities, subject to the modifications set out below. Before undertaking an impairment assessment, users of the Guidelines must be familiar with:

  • the Introduction in the Guidelines
  • chapters 1 and 2 of AMA5
  • the appropriate chapter(s) of the Guidelines for the body system they are assessing
  • the appropriate chapter(s) of AMA5 for the body system they are assessing.

The Guidelines take precedence over AMA5.

Introduction

The upper extremities are discussed in AMA5 Chapter 16 (pp 433–521). This chapter provides guidelines on methods of assessing permanent impairment involving these structures. It is a complex chapter that requires an organised approach with careful documentation of findings.

Evaluation of anatomical impairment forms the basis for upper extremity impairment (UEI) assessment. The rating reflects the degree of impairment and its impact on the ability of the person to perform ADL. There can be clinical conditions where evaluation of impairment may be difficult. Such conditions are evaluated by their effect on function of the upper extremity, or, if all else fails, by analogy with other impairments that have similar effects on upper limb function.

The approach to assessment of the upper extremity and hand

Assessment of the upper extremity mainly involves clinical evaluation. Cosmetic and functional evaluations are performed in some situations. The impairment must be permanent and stable. The claimant will have a defined diagnosis that can be confirmed by examination.

The assessed impairment of a part or region can never exceed the impairment due to amputation of that part or region. For an upper limb, therefore, the maximum evaluation is 60% whole person impairment (WPI), the value for amputation through the shoulder.

Range of motion (ROM) is assessed as follows:

  • A goniometer or inclinometer must be used, where clinically indicated.
  • Passive ROM may form part of the clinical examination to ascertain clinical status of the joint, but impairment should only be calculated using active ROM measurements. Impairment values for degree measurements falling between those listed must be adjusted or interpolated.
  • If the assessor is not satisfied that the results of a measurement are reliable, repeated testing may be helpful in this situation.
  • If there is inconsistency in ROM, then it should not be used as a valid parameter of impairment evaluation. Refer to paragraph 1.36 in the Guidelines.
  • If ROM measurements at examination cannot be used as a valid parameter of impairment evaluation, the assessor should then use discretion in considering what weight to give other available evidence to determine if an impairment is present.

To achieve an accurate and comprehensive assessment of the upper extremity, findings should be documented on a standard form. AMA5 Figures 16-1a and 16-1b (pp 436–37) are extremely useful both to document findings and to guide the assessment process.

The hand and upper extremity are divided into regions: thumb, fingers, wrist, elbow and shoulder. Close attention needs to be paid to the instructions in AMA5 Figures 16-1a and 16-1b (pp 436–37) regarding adding or combining impairments.

AMA5 Table 16-3 (p 439) is used to convert upper extremity impairment to WPI. When the Combined Values Chart is used, the assessor must ensure that all values combined are in the same category of impairment (that is WPI, upper extremity impairment percentage, hand impairment percentage and so on). Regional impairments of the same limb (eg several upper extremity impairments) should be combined before converting to percentage WPI. (Note that impairments relating to the joints of the thumb are added rather than combined – AMA5 Section 16.4d ‘Thumb ray motion impairment’, p 454.)

Specific interpretation of AMA5 – the hand and upper extremity impairment of the upper extremity due to peripheral nerve disorders

If an upper extremity impairment results solely from a peripheral nerve injury, the assessor should not also evaluate impairment(s) from AMA5 Section 16.4 ‘Abnormal motion’ (pp 450–79) for that upper extremity. AMA5 Section 16.5 should be used for evaluating such impairments.

For evaluating peripheral nerve lesions, use AMA5 Table 16-15 (p 492) together with AMA5 tables 16-10 and 16-11 (pp 482 and 484).

The assessment of carpal tunnel syndrome post-operatively is undertaken in the same way as assessment without operation.

When applying AMA5 tables 16-10 (p 482) and 16-11 (pp 482 and 484) the examiner must use clinical judgement to estimate the appropriate percentage within the range of values shown for each severity grade. The maximum value is not applied automatically.

Impairment due to other disorders of the upper extremity

AMA5 Section 16.7 ‘Impairment of the upper extremity due to other disorders’ (pp 498–507) should be used only when other criteria (as presented in AMA5 sections 16.2–16.6, pp 441–98) have not adequately encompassed the extent of the impairments. Impairments from the disorders considered in AMA5 Section 16.7 are usually estimated using other criteria. The assessor must take care to avoid duplication of impairments.

AMA5 Section 16.7 (impairment of the upper extremities due to other disorders) notes ‘the severity of impairment due to these disorders is rated separately according to Table 16-19 through 16-30 and then multiplied by the relative maximum value of the unit involved, as specified in Table 16-18’. This statement should not include tables 16-25 (carpal instability), 16-26 (shoulder instability) and 16-27 (arthroplasty), noting that the information in these tables is already expressed in terms of upper extremity impairment.

Strength evaluation, as a method of upper extremity impairment assessment, should only be used in rare cases and its use justified when loss of strength represents an impairing factor not adequately considered by more objective rating methods. If chosen as a method, the caveats detailed on AMA5 p 508 under the heading ‘16.8a Principles’ need to be observed – ie decreased strength cannot be rated in the presence of decreased motion, painful conditions, deformities and absence of parts (eg thumb amputation).

Conditions affecting the shoulder region

Most shoulder disorders with an abnormal range of movement are assessed according to AMA5 Section 16.4 ‘Evaluating abnormal motion’.

Please note that AMA5 indicates that internal and external rotation of the shoulder are to be measured with the arm abducted in the coronal plane to 90 degrees, and with the elbow flexed to 90 degrees. In those situations where abduction to 90 degrees is not possible, symmetrical measurement of rotation is to be carried out at the point of maximal abduction.

Rare cases of rotator cuff injury, where the loss of shoulder motion does not reflect the severity of the tear, and there is no associated pain, may be assessed according to AMA5 Section 16.8c ‘Strength evaluation’. Other specific shoulder disorders where the loss of shoulder motion does not reflect the severity of the disorder, associated with pain, should be assessed by comparison with other impairments that have similar effect(s) on upper limb function.

As noted in AMA5 Section 16.7b ‘Arthroplasty’, ‘In the presence of decreased motion, motion impairments are derived separately and combined with the arthroplasty impairment’. This includes those arthroplasties in AMA5 Table 16-27 designated as (isolated).

Please note that in AMA5 Table 16-27 (p 506) the figure for resection arthroplasty of the distal clavicle (isolated) has been changed to 5% upper extremity impairment, and the figure for resection arthroplasty of the proximal clavicle (isolated) has been changed to 8% upper extremity impairment.

Please note that in AMA5 Table 16-18 (p 499) the figures for impairment suggested for the sternoclavicular joint have been changed from 5% upper extremity impairment and 3% whole person impairment, to 25% upper extremity impairment and 15% whole person impairment.

Ruptured long head of biceps shall be assessed as an upper extremity impairment (UEI) of 3%UEI or 2%WPI where it exists in isolation from other rotator cuff pathology. Impairment for ruptured long head of biceps cannot be combined with any other rotator cuff impairment or with loss of range of movement.

Diagnosis of impingement is made on the basis of positive findings on appropriate provocative testing and is only to apply where there is no loss of range of motion. Symptoms must have been present for at least 12 months. An impairment rating of 3% UEI or 2% WPI shall apply.

Fractures involving joints

Displaced fractures involving joint surfaces are generally to be rated by range of motion. If, however, this loss of range is not sufficient to give an impairment rating, and movement is accompanied by pain and there is 2mm or more displacement, allow 2% UEI (1% WPI).

Epicondylitis of the elbow

This condition is rated as 2% UEI (1% WPI). In order to assess impairment in cases of epicondylitis, symptoms must have been present for at least 18 months. Localised tenderness at the epicondyle must be present and provocative tests must also be positive. If there is an associated loss of range of movement, these figures are not combined, but the method giving the highest rating is used.

Resurfacing procedures

No additional impairment is to be awarded for resurfacing procedures used in the treatment of localised cartilage lesions and defects in major joints.

Calculating motion impairment

When calculating impairment for loss of range of movement, it is most important to always compare measurements of the relevant joint(s) in both extremities. If a contralateral ‘normal/uninjured’ joint has less than average mobility, the impairment value(s) corresponding to the uninvolved joint serves as a baseline and is subtracted from the calculated impairment for the involved joint. The rationale for this decision should be explained in the assessor’s report (see AMA5 Section 16.4c, p 543).

Complex regional pain syndrome (upper extremity)

Complex regional pain syndrome types 1 and 2 should be assessed using the method in Chapter 17 of the Guidelines.

Lower extremity

AMA5 Chapter 17 (p 523) applies to the assessment of permanent impairment of the lower extremities, subject to the modifications set out below. Before undertaking an impairment assessment, users of the Guidelines must be familiar with:

  • the Introduction in the Guidelines
  • chapters 1 and 2 of AMA5
  • the appropriate chapter(s) of the Guidelines for the body system they are assessing
  • the appropriate chapter(s) of AMA5 for the body system they are assessing.

The Guidelines take precedence over AMA5.

Introduction

The lower extremities are discussed in AMA5 Chapter 17 (pp 523–564). This section is complex and provides a number of alternative methods of assessing permanent impairment involving the lower extremity. An organised approach is essential.

The approach to assessment of the lower extremity

Assessment of the lower extremity involves physical evaluation, which can use a variety of methods. In general, the method should be used that most specifically addresses the impairment present. For example, impairment due to a peripheral nerve injury in the lower extremity should be assessed with reference to that nerve rather than by its effect on gait.

There are several different forms of evaluation that can be used, as indicated in AMA5 sections 17.2b to 17.2n (pp 528–54). AMA5 Table 17-2 (p 526) indicates which evaluation methods can be combined and which cannot. It may be possible to perform several different evaluations, as long as they are reproducible and meet the conditions specified below and in AMA5. The most specific method of impairment assessment should be used.

Please note that in Table 17-2, the boxes in the fourth row (on muscle strength) and seventh column (on amputation) should be closed boxes x rather than open boxes.

It is possible to use an algorithm to aid in the assessment of lower extremity impairment (LEI). Use of a worksheet is essential. Table 3.5 at the end of this chapter is such a worksheet and may be used in assessment of permanent impairment of the lower extremity.

In the assessment process, the evaluation giving the highest impairment rating is selected. That may be a combined impairment in some cases, in accordance with the AMA5 Table 17-2 ‘Guide to the appropriate combination of evaluation methods’, using the Combined Values Chart on pp 604–06 of AMA5.

When the Combined Values Chart is used, the assessor must ensure that all values combined are in the same category of impairment rating (ie percentage of WPI, percentage of lower extremity impairment, foot impairment percentage, and so on). Regional impairments of the same limb (eg several lower extremity impairments) should be combined before converting to a percentage of whole person impairment (WPI).

AMA5 Table 17-2 (p 526) AMA5) needs to be referred to frequently to determine which impairments can be combined and which cannot. The assessed impairment of a part or region can never exceed the impairment due to amputation of that part or region. For the lower limb, therefore, the maximum evaluation is 40% WPI, the value for proximal above-knee amputation.

Specific interpretation of AMA5 – the lower extremity

Leg length discrepancy

When true leg length discrepancy is determined clinically (see AMA5 Section 17.2b, p 528), the method used must be indicated (eg tape measure from anterior superior iliac spine to the medial malleolus). Clinical assessment of leg length discrepancy is an acceptable method, but if full-length computerised tomography films are available, they should be used in preference. Such an examination should not be ordered solely for determining leg lengths.

Note that the figures for lower limb impairment in AMA5 table 17-4 (p 528) are incorrect. The correct figures are shown below.

AMA5 table 17-4: Impairment due to limb length discrepancy

Discrepancy (cm)Whole person (lower extremity) impairment (%)
0-1.90
2-2.93 (8)
3-3.95 (13)
4-4.97 (18)
5+8 (19)

Gait derangement

Assessment of gait derangement is only to be used as a method of last resort. Methods of impairment assessment most fitting the nature of the disorder should always be used in preference. If gait derangement (AMA5 Section 17.2c, p 529) is used, it cannot be combined with any other evaluation in the lower extremity section of AMA5.

Any walking aid used by the subject must be a permanent requirement and not temporary.

In the application of AMA5 Table 17-5 (p 529), delete item ‘b’, as the Trendelenburg sign is not sufficiently reliable.

Muscle atrophy (unilateral)

AMA5 Section 17.2d (p 530) is not applicable if the limb other than that being assessed is abnormal (eg if varicose veins cause swelling, or if there is another injury or condition which has contributed to the disparity in size).

Note that the figures for lower limb impairment given in AMA5 Table 17-6 (p 530) are incorrect. The correct figures are shown below.

AMA5 Table 17-6: Impairment due to unilateral leg muscle atrophy

Difference in circumference (cm)Impairment degreeWhole person (lower extremity) impairment (%)
a. Thigh: The circumference is measured 10cm above the patella, with the knee fully extended and the muscles relaxed.
0-0.9None0 (0)
1-1.9Mild2 (6)
2-2.9Moderate4 (11)
3+Severe5 (12)]
Difference in circumference (cm)Impairment degreeWhole person (lower extremity) impairment (%)
b. Calf: The maximum circumference on the normal side is compared with the circumference at the same level on the affected side.
0-0.9None0 (0)
1-1.9Mild2 (6)
2-.29Moderate4 (11)
3+Severe5 (12)

Manual muscle strength testing

The Medical Research Council gradings for muscle strength are universally accepted. They are not linear in their application, but ordinal. Only the six grades (0–5) should be used, as they are reproducible among experienced assessors. The descriptions in AMA5 Table 17-7 (p 531) are correct. The results of electrodiagnostic methods and tests are not to be considered in evaluating muscle testing, which can be performed manually. AMA5 Table 17-8 (p 532) is to be used for this method of evaluation.

Range of motion

Although range of motion (ROM) appears to be a suitable method for evaluating impairment (see AMA5 Section 17.2f, pp 533–38), it may be subject to variation because of pain during motion at different times of examination, possible lack of cooperation by the person being assessed and inconsistency. If there is such inconsistency, then ROM cannot be used as a valid parameter of impairment evaluation.

AMA5 Table 17-10 (p 537) is misleading as it has valgus and varus deformity in the same table as restriction of movement, possibly suggesting that these impairments may be combined. This is not the case. Any valgus/ varus deformity present which is due to the underlying lateral or medial compartment arthritis, cannot be combined with loss of range of movement. Therefore, when faced with an assessment in which there is a rateable loss of range of movement as well as a rateable deformity, calculate both impairments and use the greater. Valgus and varus knee angulation are to be measured in a weight-bearing position using a goniometer. It is important to bear in mind that valgus and/or varus alignments of the knee may be constitutional. It is also important to always compare with the opposite knee.

If range of motion is used as an assessment measure, then AMA5 Tables 17-9 to 17 14 (p 537) are selected for the joint or joints being tested. If a joint has more than one plane of motion, the impairment assessments for the different planes should be added. For example, any impairment of the six principal directions of motion of the hip joint are added (see AMA5, p 533).

In AMA5 Table 17-10 (p 537), on knee impairment, the sentence should read: ‘Deformity measured by femoral-tibial angle; 3° to 9° valgus is considered normal’.

In AMA5 Table 17-11 (ankle motion) the range for mild flexion contracture should be one to 10°, for moderate flexion contracture it should be 11° to 19°, and for severe flexion contracture it should be 20° plus.

The revised Table 17-11 is below.

AMA5 Table 17-11: Ankle motion impairment estimates

Whole person (lower extremity) [foot' impairment
MotionMild
3% (7%) [10%]
Moderate
6% (15%) [21%]
Severe
12% (30%) [43%]
Plantar flexion capability11°-20°1°-10°None
Flexion contracture1°-10°11°-19°20°+
Extension10°-0° (neutral)--

When calculating impairment for loss of range of movement, it is most important to always compare measurements of the relevant joint(s) in both extremities. If a contralateral ‘normal/uninjured’ joint has less than average mobility, the impairment value(s) corresponding to the uninvolved joint serves as a baseline, and is subtracted from the calculated impairment for the involved joint. The rationale for this decision should be explained in the assessor’s report (see AMA5 Section 16.4c, p 454).

Ankylosis

Ankylosis is to be regarded as the equivalent to arthrodesis in impairment terms only. For the assessment of impairment, when a joint is ankylosed (AMA5 section 17.2g, pp 538-543), the calculation to be applied is to select the impairment if the joint is ankylosed in optimum position (see table 3.1 below), and then if not ankylosed in the optimum position, by adding (not combining) the values of percentage of WPI using tables 17-15 to 17-30 (pp 538-543 AMA5).

Table 3.1(a): Impairment for ankylosis in the optimum position

Whole person (lower extremity) [foot] impairment
Position2 (5) [7]%4 (10) [14]%7 (17) [24]%10 (25) [35]%
Dorsiflexion5°-9°10°-19°20°-29°30°+
Plantar flexion-10°-19°20°-29°30°+
Varus5°-9°10°-19°20°-29°30°+
Valgus-10°-19°20°-29°30°+
Internal rotation0°-9°10°-19°20°-29°30°+
External rotation15°-19°20°-29°30°-39°40°+

Arthritis

Impairment due to arthritis (AMA5 Section 17.2n, pp 544–45) following a work-related injury is uncommon, but may occur in isolated cases. The presence of arthritis may indicate a pre-existing condition and this should be assessed and an appropriate deduction made (see Chapter 1).

The presence of osteoarthritis is defined as cartilage loss. Cartilage loss can be measured by properly aligned plain X-ray, or by direct vision (arthroscopy), but impairment can only be assessed according to the radiologically determined cartilage loss intervals shown in AMA5 Table 17-31 (p 544). When assessing impairment of the knee joint, which has three compartments, only the compartment with the major impairment is used in the assessment. That is, measured impairments in the different compartments cannot be added or combined.

Detecting the subtle changes of cartilage loss on plain radiography requires comparison with the normal side. All joints should be imaged directly through the joint space, with no overlapping of bones. If comparison views are not available, AMA5 Table 17-31 (p 544) is used as a guide to assess joint space narrowing.

One should be cautious in making a diagnosis of cartilage loss on plain radiography if secondary features of osteoarthritis, such as osteophytes, subarticular cysts or subchondral sclerosis are lacking, unless the other side is available for comparison. The presence of an intra-articular fracture with a step in the articular margin in the weight-bearing area implies cartilage loss.

The accurate radiographic assessment of joints always requires at least two views. In some cases, further supplementary views will optimise the detection of joint space narrowing or the secondary signs of osteoarthritis.

Sacro-iliac joint: Being a complex joint, modest alterations are not detected on radiographs, and cross sectional imaging may be required. Radiographic manifestations accompany pathological alterations. The joint space measures between 2mm and 5mm. Osteophyte formation is a prominent characteristic of osteoarthritis of the sacro-iliac joint.

Hip: An anteroposterior view of the pelvis and a lateral view of the affected hip are ideal. If the affected hip joint space is narrower than the asymptomatic side, cartilage loss is regarded as being present. If the anteroposterior view of the pelvis has been obtained with the patient supine, it is important to compare the medial joint space of each hip, as well as superior joint space, as this may be the only site of apparent change. If both sides are symmetrical, then other features, such as osteophytes, subarticular cyst formation, and calcar thickening, should be taken into account to make a diagnosis of osteoarthritis.

Knee – Tibio-femoral joint: The best view for assessment of cartilage loss in the knee is usually the erect intercondylar projection, as this profiles and stresses the major weight-bearing area of the joint, which lies posterior to the centre of the long axis. The ideal X-ray is a posteroanterior view, with the patient standing, knees slightly flexed, and the X-ray beam angled parallel to the tibial plateau (Rosenberg view). Both knees can be readily assessed with the one exposure. It should be recognised that joint space narrowing in the knee does not necessarily equate with articular cartilage loss, as deficiency or displacement of the menisci can also have this effect. Secondary features, such as subchondral bone change and past surgical history, must also be taken into account.

Knee – Patello-femoral joint: This should be assessed in the ‘skyline’ view, again preferably with the other side for comparison. The X-ray should be taken with 30 degrees of knee flexion to ensure that the patella is load-bearing and has engaged the articular surface femoral groove.

Footnote to AMA5 Table 17-31 (p 544) regarding patello-femoral pain and crepitation:

This item is only to be used if there is a history of direct injury to the front of the knee, or in cases of patellar translocation/dislocation without direct anterior trauma. This item cannot be used as an additional impairment when assessing arthritis of the knee joint itself, of which it forms a component. If patello-femoral crepitus occurs in isolation (ie with no other signs of arthritis) following either of the above, then it can be combined with other diagnosis-based estimates (AMA5 Table 17-33, p 546). Signs of crepitus need to be present at least one year post-injury.

Note: Osteoarthritis of the patello-femoral joint cannot be used as an additional impairment when assessing arthritis of the knee joint itself, of which it forms a component.

Ankle: The ankle should be assessed in the mortice view (preferably weight-bearing), with comparison views of the other side, although this is not as necessary as with the hip and knee.

Subtalar: This joint is better assessed by CT (in the coronal plane) than by plain radiography. The complex nature of the joint does not lend itself to accurate and easy plain X-ray assessment of osteoarthritis.

Talonavicular and calcaneocuboid: Anteroposterior and lateral views are necessary. Osteophytes may assist in making the diagnosis.

Intercuneiform and other intertarsal joints: Joint space narrowing may be difficult to assess on plain radiography. CT (in the axial plane) may be required. Associated osteophytes and subarticular cysts are useful adjuncts to making the diagnosis of osteoarthritis in these small joints.

Great toe metatarsophalangeal: Anteroposterior and lateral views are required. Comparison with the other side may be necessary. Secondary signs may be useful.

Interphalangeal: It is difficult to assess small joints without taking secondary signs into account. The plantar-dorsal view may be required to get through the joints, in a foot with flexed toes.

If arthritis is used as the basis for assessing impairment, then the rating cannot be combined with gait disturbance, muscle atrophy, muscle strength or range of movement assessments. It can be combined with a diagnosis-based estimate (AMA5 Table 17-2, p 526).

Amputation

Where there has been amputation of part of a lower extremity Table 17-32 (p 545, AMA5) applies. In that table, the references to three inches for below the knee amputation should be converted to 7.5cm.

Diagnosis-based estimates (lower extremity)

AMA5 Section 17.2j (pp 545–49) lists a number of conditions that fit a category of diagnosis-based estimates. They are listed in AMA5 Tables 17-33, 17-34 and 17-35 (pp 546–49). When using this table it is essential to read the footnotes carefully. The category of mild cruciate and collateral ligament laxity has inadvertently been omitted in Table 17-33. The appropriate rating is 5 (12)% whole person (lower extremity) impairment.

It is possible to combine impairments from Tables 17-33, 17-34 and 17-35 for diagnosis-related estimates with other components (eg nerve injury) using the Combined Values Chart (AMA5, pp 604–06) after first referring to the Guidelines for the appropriate combination of evaluation methods (see Table 3.5).

Pelvic fractures: Pelvic fractures are to be assessed as per Table 4.3 in the Guidelines, and not as per AMA5 Table 17-33 (p 546).

Hip: The item in relation to femoral neck fracture ‘malunion’ is not to be used in assessing impairment. Use other available methods.

Femoral osteotomy:

  • Good result: 10 (25)
  • Poor result: Estimate according to examination and arthritic degeneration

Tibial plateau fractures: Table 3.2 of the Guidelines, replaces the instructions for tibial plateau fractures in AMA5 Table 17-33 (p 546).

Table 3.2: Impairment for tibial plateau fractures

In deciding whether the fracture falls into the mild, moderate or severe categories, the assessor must take into account:

  • the extent of involvement of the weight-bearing area of the tibial plateau
  • the amount of displacement of the fracture(s)
  • the amount of comminution present.
GradeWhole person (lower extremity) impairment (%)
Undisplaced2 (5)
Mild5 (12)
Moderate10 (25)
Severe15 (37)

Patello-femoral joint replacement: Assess the knee impairment in the usual way and combine with 9% WPI (22% LEI) for isolated patello-femoral joint replacement.

Total ankle replacement:

Table 3.3: Rating for ankle replacement results

The points system for rating total ankle replacements is to be the same as for total hip and total knee replacements, with the following impairment ratings:

  
  
  
  

Result WPI (LEI) % Good result: 85–100 points: 12 (30) Fair result: 50–84 points: 16 (40) Poor result: <50 points: 20 (50)