Guidelines for the assessment of permanent impairment Version 3

3.27 It is possible to combine impairments from Table 64 for diagnosis- based estimates with othercomponents (e.g. nerve injury) using the Combined Values Chart (pp 322 - 324, AMA 4 Guides),having regard for 3.2 of these Guidelines.3.28 In the interpretation of Table 64, reference to the hind-foot, intra-articular fractures, the wordssubtalar bone, talonavicular bone, and calcaneocuboid bone imply that the bone is displaced on oneor both sides of the joint mentioned.3.29 In order to avoid the risk of double assessment, if avascular necrosis with collapse is used as thebasis of assessment, it cannot be combined with intra-articular fracture of the ankle withdisplacement or intra-articular fracture of the hind-foot with displacement (QV Table 64 column 1page 86 AMA 4 Guides).3.30 Table 65 and Table 66 (pp 87 - 88, AMA 4 Guides) use a different concept of evaluation. A pointscore system is applied, and then the total of points calculated for the hip, or knee, joint respectivelyis converted to an impairment rating from Table 64. Tables 65 and 66 refer to the hip and kneejoint replacement respectively. Note that, while all the points are added in Table 65, some pointsare deducted when Table 66 is used.3.31 In respect of Table 65, the references to “distance walked” under “b. Function” should be construedas six blocks being 600 metres, and three blocks being 300 metres.3.32 Pelvic fractures should be assessed using section 3.4 (p 131 AMA 4 Guides). Fractures of theacetabulum should be assessed using Table 64 (pp 85 - 86, AMA 4 Guides).Skin Loss (lower extremity)3.33 Skin loss (p 88, AMA 4 Guides) can only be included in the calculation of impairment if it is in certainsites and meets the criteria listed in Table 67 (p 88, AMA 4 Guides).Peripheral Nerve Injuries (lower extremity)3.34 When assessing the impairment due to peripheral nerve injury (pp 88-89, AMA 4 Guides), medicalassessors should read the text in this section. Note that the separate impairments for the motor,sensory and dysaesthetic components of nerve dysfunction in Table 68 (p 89, AMA 4 Guides) are tobe combined.3.35 Note that the (posterior) tibial nerve is not included in Table 68, but its contribution can be calculatedby subtraction of common peroneal nerves from sciatic nerve ratings. The tibial nerve can beassessed as follows with reference to Table 68. The values in brackets are lower extremityimpairment values.WCT Guidelines 1 October 2011 19