Can Knee Arthritis Qualify as a Work Injury in Ontario?

What Does a Worker Need to Prove for a WSIB Knee Injury Claim?

To receive WSIB benefits for a knee injury, a worker must show that a personal work-related injury occurred, that there is proof of an accident (either a discrete event or a gradual disablement), and that the diagnosis is compatible with the claimed work history. Meeting all three requirements is harder than many workers expect — especially when the underlying condition is degenerative.

In Decision No. 515/26, 2026 ONWSIAT 748 (CanLII), the Workplace Safety and Insurance Appeals Tribunal (WSIAT) denied benefits to a long-service sanitation worker at a food manufacturer who developed bilateral knee problems, including a medial meniscal tear and patellofemoral arthritis, after nearly two decades on the job. The panel’s reasoning offers a clear picture of where these claims succeed and where they fall short.

What Is the Difference Between a Chance Event and a Disablement Claim?

A “chance event” is a specific, identifiable incident at work that causes an injury — for example, a fall or a sudden twist. A “disablement” is a condition that emerges gradually from the nature of the work over time, or an unexpected result of working duties that cannot be traced to a single moment.

The worker in this case pursued both paths. She reported that her knees gave out on a staircase while carrying chemical jugs at work in January 2021, and she also claimed that her knee condition developed gradually from years of standing, walking, crouching, and kneeling on concrete floors. The tribunal examined each claim separately.

Why Was the Incident Claim Denied Even Though a Co-Worker Witnessed It?

A witnessed incident is important evidence, but it does not automatically establish a compensable injury. The panel accepted that the worker’s knees gave out on the stairs — the co-worker’s statement confirmed it. The problem was what happened next: the worker got up, finished her shift, did not report any knee injury to her employer, and did not seek medical attention for her knees. Her concern that day was her back, not her knees.

Under WSIB policy, a “personal work-related injury” must actually have occurred. Continuing to work without any contemporaneous complaint about the knees made it very difficult to establish that the incident caused a knee injury within the meaning of the policy. The claim for that date was filed 21 months later, only after a WSIB adjudicator prompted the worker to think about whether there was another possible incident date.

What Evidence Is Needed to Win a Gradual-Onset Knee Claim?

For a disablement claim, the worker’s job duties must have made a significant contribution to the onset of the condition. The panel looks at how repetitive the work was, the physical nature of the duties, changes in workload, and the general work environment.

Here, the panel found that kneeling and crouching — the activities most directly linked to knee stress — occurred only occasionally. Cleaning under kettles took roughly 45 minutes and happened about twice a week. That was not enough to establish significant biomechanical loading on the knees. Crucially, neither of the two orthopedic surgeons who treated the worker attributed her condition to her job. The only medical opinion linking the work to the injury came from her family doctor, and that opinion contradicted an earlier statement from the same doctor who had said it was “impossible to tell” whether the condition was work-related.

How Does Age and Degenerative Arthritis Affect a WSIB Knee Claim?

Degenerative meniscal tears and osteoarthritis are extremely common in people over 50, and medical literature cited by the tribunal notes they often occur with minimal or no trauma. When the medical evidence points to age-related degeneration as the likely cause, it becomes very difficult to establish that work was a significant contributing factor.

The panel noted that the worker’s new meniscal tear — which developed after she stopped working for the employer — further suggested her knee condition was not tied to that specific workplace. Our Ontario employment lawyers regularly advise workers navigating these evidentiary challenges, including how to gather the right medical documentation from the outset.

What Did Prior WSIAT Decisions Say About Occupational Knee Injuries?

The worker’s representative cited three earlier WSIAT decisions where workers succeeded on knee claims. The panel distinguished all three. One involved a plumber with over 40 years of significant kneeling and heavy stair-climbing, supported by an occupational health specialist who confirmed substantial biomechanical loading. Another involved a worker whose duties increased markedly over several months in a confined, slippery environment. A third involved an acute meniscal tear causally linked to a specific fall — not a degenerative tear.

The lesson from these comparisons is that context matters enormously. The degree of physical loading, the duration of exposure, the type of tear (acute versus degenerative), and the quality of occupational health evidence all affect the outcome. Workers in Hamilton, Burlington, and across Ontario who work in physically demanding environments should understand that the strength of their medical evidence — not just the nature of the job — is often decisive. If you are in the Hamilton or Burlington area, our Hamilton employment law team can help you understand your options.

Questions and Records to Discuss with a Lawyer

• What medical records do you have from the time your symptoms first appeared, and do any of them comment on whether your condition is work-related?
• Did you report your symptoms to your employer promptly, and is there a written record of that report?
• Have any of your treating specialists — not just your family doctor — provided a written opinion connecting your diagnosis to your specific job duties?
• Were your physically demanding duties (kneeling, crouching, heavy lifting) documented anywhere, such as a job posting, a functional demands analysis, or an incident report?
• Has your condition continued to progress or recurred since you stopped doing the work in question?

If you have questions about a WSIB claim denial or want to understand your rights under Ontario’s workers’ compensation system, you are welcome to reach out to UL Lawyers through our contact page to discuss your specific circumstances.

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This article is automated commentary on a public court decision and is for general information only — not legal advice. Decisions rely on facts unique to each case. If you are affected by a similar issue, contact a lawyer for advice specific to your situation.