Impairment, disability and pain

By Dr Malcolm Wallace

One of the most important issues I face as an independent examiner is to determine the impairment an injured person sustains, in percentage terms, usually in accordance with the AMA Guides and as a result of a personal injury where there is a liability.

In any injury which results in a permanent disability, that disability needs to be quantified in terms of a percentage, so that within our administrative framework a just compensation will be settled. This will be in terms of a Whole Person Impairment. It is necessary to have an impairment of a bodily function to lead to an assessment for compensation purposes. If there is no assessable impairment, then perhaps there is no disability. But is this truly the case? Is it the assessable impairment, or the disability which arises from the injury which determines the claimant’s current state when compared to their previous pre-injury state?

By way of clarification I will quote the AMA Guides definitions of which I am sure you are aware: ‘The Guides continue to define impairment as a loss, loss of use, or derangement of any body part, organ system, or organ function.

‘The Guides continues to define disability as an alteration of an individual’s capacity to meet personal, social or occupational demands or statutory or regulatory requirements because of an impairment’ (The emphasis is mine).

Once established, the impairment is considered to be either wholly or partially due to an injury. If there is a significant pre-existing disorder or condition which impacts upon the assessment, then there must be an attempt on the part of the assessor to attribute between the quantity of impairment to the pre-existing condition and that to the injury. This is inherently difficult in situations where there is a pre-existing but asymptomatic (e.g. degenerative) condition which predisposes to, but does not in itself cause an impairment or its consequential disability.

By way of illumination I will provide the following case study:

• Female aged 53
• Disability support pension for chronic lumbar pain and bipolar disorder for the last eight years
• Last employed 25 years ago

Significant co-morbidities:

• Opiate dependence
• Hypertension
• Rheumatoid arthritis
• Obesity
• Sleep apnoea

Prior long history of lower back pain and cervical pain.

Injury to cervical spine in rear-ending low speed motor vehicle accident 12 months ago.

The subject did not require assistance from emergency services at the time of the accident and was able to extricate herself and went home with a relative, subsequently attending upon her General Practitioner complaining of posterior cervical spine pain, with right-sided upper limb radicular symptoms, headaches and unsteady gait, requiring the use of a walking frame. Investigations revealed degenerative changes in the cervical spine with no acute bony injury, but with significant central canal stenosis and foraminal stenosis bilaterally at C5/6.

A referral was made to a spinal surgery centre at a public hospital. Upon review, the treating specialist diagnosed a myelopathy associated with the central canal stenosis and recommended decompressive surgery and cervical fusion. This was subsequently undertaken without early post-operative complications.

Post-operative rehabilitation was undertaken and the subject’s disability remains unchanged. The subject patient is now seeking compensation for damages associated with the accident.

This case illustrates some of the challenges in assessment of the impairment which was the result of the motor vehicle accident.

• The subject had advanced, pre-existing asymptomatic degenerative cervical spinal stenosis
• The subject then, as a result of the motor vehicle accident, developed symptoms of cervical myelopathy and also radiculopathy
• The subject underwent surgical stabilisation and decompression to treat the myelopathy but not the radiculopathy and continues to suffer ongoing symptoms

With respect to the assessment of impairment, using AMA Guides, 5th Edition, this subject would qualify under Table 15.5 as having a DRE IV category, allowing a 25%-28% impairment. However, the majority of this impairment is attributable to a pre-existing condition even though that pre-existing condition was asymptomatic.

Nevertheless, the subject would not be in her current state of disability were it not for the accident and were it not for the accident, she would have in probability not required the surgery which has elevated her assessable impairment from 0% to 25-28%.

I reserve my opinion in this case and present it for the interest of our audience.