Many workers assume that if they already had arthritis, a bad back, worn knees or an old injury, they will not be entitled to Workers Compensation if that condition gets worse due to work.

A recent decision of the South Australian Employment Tribunal (SAET) shows that assumption can be very wrong.

The case involved a worker whose claim was challenged because he already had significant degeneration in his knee and a long history of knee problems. Of particular note was the fact that the worker did not experience any dramatic incident or sudden injury at work. Instead, after a long shift involving repetitive work duties, he noticed significant pain and swelling in his knee the following morning.

Despite arguments that his condition was simply the result of age and pre-existing arthritis, the Tribunal ultimately found that his work duties were a “significant contributing cause” of his injury and ongoing incapacity.

Do Work Injuries Have to Happen Suddenly?

One of the most interesting aspects of this case is that there was no obvious workplace accident.

The worker had been performing long shifts at a plastics recycling plant and said that on one particular day he had repeatedly climbed on and off a forklift throughout the shift. He estimated that he got in and out of the forklift approximately 200 times during the day.

At the end of the shift he said he felt generally sore and fatigued, but he did not notice any significant issue specifically with his knee at the time.

It was only when he woke up the next morning that he noticed substantial pain and swelling in his right knee. Over the following days the symptoms worsened to the point where he struggled to bend the knee and was unable to continue working.

That is important because many workers assume:

“If I didn’t feel something snap at work, I probably can’t claim Workers Compensation.”

This case demonstrates that work injuries do not always happen in one dramatic moment. Some injuries develop gradually through repetitive duties, long shifts, strain placed on joints over time or the aggravation of an underlying condition.

Can Workers Compensation Cover a Pre-Existing Injury?

The worker in this case already had a long history of knee problems.

Medical records showed he had previously undergone surgery to the knee and had significant degenerative changes and osteoarthritis before the claimed work injury occurred. The employer and Return to Work Corporation argued that his ongoing symptoms were simply the result of those pre-existing conditions rather than his employment.

However, the Tribunal accepted that the repetitive work duties had aggravated the condition.

One of the orthopaedic specialists described the worker as having:

“clearly exacerbated his underlying osteoarthritis”.

That finding became central to the case.

Importantly, the law does not require work to be the only cause of an injury. In many Workers Compensation cases, employment only needs to be a “significant contributing cause” of the condition or incapacity.

This is particularly important for older workers and those with physically demanding jobs. Many people continue working despite arthritis, old injuries or wear and tear. If work duties aggravate or accelerate those conditions, there may still be an entitlement to Workers Compensation.

What If the Employer Says It Was “Just Arthritis”?

That was effectively the argument made in this case.

The claim was rejected on the basis that the worker already had severe degeneration in his knee and that there had been no specific accident at work.

The Tribunal ultimately disagreed.

It accepted that although the worker had pre-existing degeneration, the repetitive duties performed during the shift significantly contributed to the worsening of the condition and the worker’s incapacity.

Importantly, the Tribunal also accepted that the work injury contributed to the worker ultimately requiring a total knee replacement.

This highlights an important point in Workers Compensation claims involving arthritis or old injuries. The existence of degeneration does not automatically prevent a successful claim.

The real question is often whether the work duties aggravated, accelerated or contributed significantly to the condition becoming symptomatic or disabling.

What Types of Work Can Cause Gradual Injuries?

Many people associate Workers Compensation claims with falls, machinery accidents or traumatic incidents.

However, many successful claims arise from repetitive work activities and strain placed on the body over time.

This can include:

• repetitive lifting or bending,
• climbing in and out of machinery,
• physically demanding shifts,
• repetitive shoulder or arm movements,
• prolonged standing or walking,
• or repetitive strain on already vulnerable joints.

Often workers continue pushing through pain until the condition suddenly becomes much worse.

Why This Decision Matters for Older Workers

One reason this decision is likely to resonate with many workers is that it reflects the reality of modern workplaces.

Not every worker is young and injury-free. Many people continue working with old sporting injuries, arthritis, worn joints or previous surgeries.

Workers often assume they are not entitled to compensation because:

• they are “getting older”,
• they already had back or knee problems,
• or because there was no dramatic workplace accident.

This case shows that those assumptions are not always correct.

Even where there is a significant pre-existing condition, a worker may still be entitled to compensation if their employment materially aggravates or accelerates that condition.

Need Advice About a Workers Compensation Claim?

Workers Compensation claims involving arthritis, degeneration or pre-existing injuries are often disputed by employers and insurers. These cases can be medically and legally complex, particularly where there is disagreement about whether work duties significantly contributed to the condition.

Websters Lawyers have extensive experience acting for injured workers in disputed Workers Compensation claims, including cases involving repetitive strain injuries, aggravation of pre-existing conditions and gradual onset injuries.

We can advise you on:

• whether you may have an entitlement to compensation,
• how pre-existing conditions are treated,
• and what evidence may assist your claim.

We offer a free initial telephone consultation to discuss your situation and provide practical advice about your options.

Call 8231 1363 to speak with one of our experienced Workers Compensation lawyers.

Loader v Return to Work Corporation of South Australia & Recycling Plastics Australia Pty Ltd [2026] SAET 45