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Medical assessor guidance note 2

Musculoskeletal system: lower extremity impairment

Assessment of femoral shaft fracture, rotational deformity

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.

References

  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 3.26, page 16.
  2. The American Medical Association Guides to the Evaluation of Permanent Impairment, 4th Edition (AMA 4 Guides): Chapter 3 3.2i Diagnosis-based Estimates, Table 64 page 85.

Background

Method of measuring rotational deformity of femoral shaft fractures is not dealt with in the AMA 4 Guides.

Issue requiring clarification

In the absence of prescribed methodology in the AMA 4 Guides for measuring rotational deformity following femoral shaft fractures it is possible that some Medical Assessors may not focus attention on this deformity and may not provide an impairment rating.

Preferred interpretation

Medical Assessors should assign the values for femoral shaft fracture, healed with malrotation as per Table 64 page 85 AMA 4 Guides for rotational deformity.

Recommended method for measurement of femoral shaft malrotation to assess possible rotational malalignment following femoral shaft fracture.

Femoral malrotation is the degree of rotation of the femur along its long axis from the hip to the knee.

Malrotation of the femur is determined indirectly by measuring internal and external rotation of the hip joint.

Internal and external rotation of the hip joints is measured with a goniometer either in the prone position with the knees flexed to 90° or in the supine position with hips and knees flexed to 90°.

An external rotation deformity is diagnosed if the injured side has an excessive degree of external rotation and a corresponding decrease in the range of internal rotation. The degree of deformity is determined by comparing the ranges of movement on the injured side with the ranges of movement on the normal side (which is therefore used as a baseline).

An example depicting an external rotation deformity

In the following example external rotation is 15° greater than normal and internal rotation 15° less than normal. There is therefore evidence of a 15° external rotation deformity (15° malrotation of the femur).

 

Right hip

Left hip

External Rotation

50 °

35 °

Internal Rotation

10 °

25 °

An internal rotation deformity is determined in similar fashion.

Suggested method of assessment of impairment

The level of impairment for femoral rotational malalignment following femoral shaft fractures is derived from Table 64 Page 85 AMA 4 Guides.

Justification for preferred interpretation

In the absence of a prescribed methodology in AMA 4 Guides for measuring rotational deformity of femoral shaft fracture, the preferred interpretation and methodology is suggested to promote consistency of assessment.


Issued by:

Injury Strategy Branch

February 2012