Medical assessor guidance note 25

Musculoskeletal system: Lower extremity impairment

This material is issued by the Motor Accidents Authority under s.65(2) of the Motor Accidents Compensation Act 1999 (the Act) in the interests of promoting accurate and consistent medical assessments under the Act. The interpretation provided here is not legally binding but represents the clinically recommended interpretation in an area where more than one interpretation of existing provisions may be possible. This recommended interpretation is publically available. Any medical assessment which does not adopt this interpretation should be accompanied by clinical justification for the interpretation adopted, supported by full, robust reasons.


  1. The Motor Accidents Authority Permanent Impairment Guidelines – Guidelines for the assessment of permanent impairment of a person injured as a result of a motor vehicle accident 1 October 2007 (MAA Guidelines): Chapter 3 Lower Extremity Impairment, clause 3.18, page 15.
  2. The American Medical Association Guides to the Evaluation of Permanent Impairment, 4th edition (AMA 4 Guides): Chapter 3 3.2e Range of Motion Tables 40 - 45, page 78.


The PI Guidelines direct that if range of movement is used as an assessment measure, then Tables 40 to 45 of the AMA 4 Guides are selected for the joints or joints being tested.

Issue requiring clarification

The PI Guidelines at clause 3.18 state that:

‘If range of motion is used as an assessment measure, Tables 40 to 45 (p.78, AMA 4 Guides) are selected for the joint or joints being tested. Where a joint has more than one range of motion, and the impairment assessment is different (i.e. mild, moderate or severe) for the different directions, then only the highest level of impairment is selected’.

The clause is deficient in not clearly stating, where the impairments for each ROM plane are the same, then only one of the impairments is selected, not added or combined. The AMA 4 Guide is also silent.

Preferred interpretation

The Medical Assessor should use the following approach when using Tables 40 to 45 (p 78, AMA 4 Guides) to assess range of motion in the lower extremities. Where there is loss of motion in more than one direction/axis of the same joint, only the most severe deficit is rated; the ratings for each motion deficit are not added or combined. However, motion deficits arising from separate tables can be combined.

The Medical Assessor should provide reasons to support all ratings allocated and reference the presence and description of all impairment categories.

Justification for preferred interpretation

The preferred interpretation and methodology as outlined above is suggested to promote consistency of assessment.

Injury Prevention and Rehabilitation
August 2017