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Permanent impairment guidelines Table 4.2 interpretation and application

The information provides clarification regarding Table 4.2: Modifiers for DRE categories following surgery’ which can be found in the Spine chapter of the NSW workers compensation guidelines for the evaluation of permanent impairment 4th edition (Guidelines).

We have provided this in collaboration with the permanent impairment assessors of the spine, who are also members of the NSW Permanent Impairment Coordinating Committee.

Is Table 4.2 of the Guidelines applicable in the absence of verifiable radiculopathy?

Yes.

Table 4.2 was modified in the 4th edition of the Guidelines to allow for a fairer assessment of permanent impairment for workers following spinal surgery.

In the WorkCover Guides for the evaluation of permanent impairment 3rd edition, Table 4.2 only applied to workers with a persisting radiculopathy at the time of assessment, regardless of the number of levels operated on and/or the number of operations, but this has changed in the 4th edition.

Under Table 4.2 in the 4th edition, the first row requires residual symptoms and radiculopathy to be present but the second, third and fourth rows do not require residual symptoms and radiculopathy to be present.

How is whole person impairment (WPI) for the spine calculated when modifiers apply from Table 4.2?

The WPI from Table 4.2 is calculated separately and then combined with the DRE:

  1. Select the appropriate DRE category from Table 15-3, 15-4, or 15-5.
  2. Determine an impairment value within the allowed range in Table 15-3, 15-4 or 15-5 according to the impact on the worker's ADLs.
  3. Combine this value with the appropriate amount from Table 4.2 to determine the final whole person impairment. i.e. Modifiers from Table 4.2 must be combined and the total amount from Table 4.2 combined with the total of the DRE category.

Example 1: Two operations

  • Initial surgery undertaken was a micro discectomy (L4/5)
  • Subsequent surgery was disc replacement (L4/5) and additional level fusion (L5/S1)
  • ADL - 1 % WPI indicated for activities of daily living impact (reduction of participation in some sports).
  • No verifiable radiculopathy present at assessment.

Response

First operation:

  • L4/5 micro discectomy

Second operation:

  • L4/5 disc replacement
  • L5/S1 fusion (second level)
    Based

Based on the information provided:

  • Lumbar DRE Category IV (as a result of fusion) = range 20%-23% WPI
  • ADL – 1% WPI for the effect of the injury on ADL = 21% WPI

Table 4.2 would then be applied as follows:

  • Total amount from Table 4.2 = 3% (after combining):
    • second operation = 2% WPI
    • second level = 1% WPI
  • Combine total for DRE Category (21% WPI) with total from Table 4.2 (3%) = 23% WPI.

Example 2: one operation

  • Single surgery undertaken by way of disc replacement (L4/5) and additional level fusion (L5/S1)
  • ADL - 1% WPI indicated for activities of daily living impact (reduction of participation in some sports).
  • No verifiable radiculopathy present at assessment.

Response

Operation:

  • L4/5 disc replacement
  • Additional level L5/S1 fusion

Based on the information provided:

Lumbar DRE Category IV (as a result of fusion) = range 20%-23% WPI

ADL – 1% WPI for the effect of the injury on ADL= 21% WPI

Table 4.2 would then be applied as follows:

  • Total amount from Table 4.2 = 1% (after combining):
    • Second level = 1% WPI
  • Combine total for DRE Category (21% WPI) with value from Table 4.2 (1%) = 22% WPI.