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Medical assessor guidance note 12

Musculoskeletal system: The Upper Extremity

Assessment of radial deviation and ulnar deviation

Introduction

This material is issued by the MAA under s.65(2) of the Motor Accidents Compensation Act 1999 (as amended), 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 publicly 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.

References

  • 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 2.
  • The American Medical Association Guides to the Evaluation of Permanent Impairment, 4th Edition (AMA 4 Guides): Chapter 3 Section 3.1h The Wrist, pages 35 -38

Background

The AMA 4 Guides direct that active range of movement is to be used as the primary method for the assessment of joint impairment in the upper extremity. The range of motion of a joint is the total number of degrees of movement traced by an arc between the extreme angles of motion of the joint. Chapter 3 of AMA 4 Guides contains range of motion (arc) figures for each plane of movement in the joints of the upper extremity.

Issue requiring clarification

The range of motion figures for evaluating hand and upper extremity impairment measure movement to the nearest 10° with one exception. Figure 29 (page 38), which deals with radial and ulnar deviation of the wrist, measures movement to the nearest 5°. The upper extremity impairment ratings for decreased radial and ulnar deviation are thus listed for 5° intervals.

There is inconsistency between the ranges listed in Figure 29 and the methodology described on page 37 of AMA 4 Guides under the heading, Wrist: Radial and Ulnar Deviation. The description of the methodology states:

  1. Measure maximum radial and ulnar deviation and record the goniometer readings. Round the figures to the nearest 10°. The normal range of motion is from 20° radial deviation to 30° ulnar deviation.
  2. From Figure 29, match the measured radial and ulnar deviation angles to the corresponding impairments of radial deviation and ulnar deviation.
  3. Add the impairment values for radial and ulnar deviation loss to obtain the upper extremity impairment value.

If the written methodology is followed then all measurements of radial and ulnar deviation at 5° intervals would be rounded up to the next 10°. For example 5° would become 10° and 15° would become 20°. In all cases the rounding up of 5° measurements would give a lesser impairment rating. In most cases this would be 1% UEI for each direction where there is a 5° measurement with a maximum of 2% UEI if both radial and ulnar deviation were affected. This could convert to a possible 1% WPI for each affected wrist.

Preferred interpretation

To remove inconsistency, the measurement of radial and ulnar deviation should be rounded to the nearest 5° and the appropriate impairment rating read from Figure 29. In other words, measurements of radial and ulnar deviation should not be rounded to the nearest 10°.

Justification for preferred interpretation

The preferred method precisely follows the impairment ratings laid out in Figure 29 of the AMA 4 Guides. Applying the preferred interpretation removes an internal inconsistency in the AMA 4 Guides and provides a more exact assessment of impairment.

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


Issued by:

Injury Strategy Branch

September 2013