How a work injury to an arthritic knee can be fully compensable, even when the worker had a pre-existing degenerative condition.
In New Jersey, under the workers' compensation law, an employer takes the worker as it finds the worker. A pre-existing arthritic knee, prior surgery, obesity, or age does not bar recovery when a workplace event materially aggravates, accelerates, or lights up a dormant or degenerative condition. The aggravation itself is the compensable injury. This principle, established for decades, continues to drive outcomes in knee, back, and joint claims across the State.
The point was illustrated in a Wyoming appellate decision, Judd v. State ex rel. Wyoming Workers' Safety & Compensation Division, 2010 WY 85, 233 P.3d 956 (Wyo. 2010), where a worker who weighed close to 250 pounds at five feet two inches, and who had already undergone a left knee replacement for end-stage degenerative arthritis, fell at work. The court reversed a denial of benefits, holding that although the degenerative condition pre-existed, the claimant had worked full-time without restriction before the fall and was disabled by debilitating pain afterward. The work injury, the court found, brought the need for surgery to a head. New Jersey law reaches the same result through its own well-developed body of precedent.
The New Jersey Standard: Material Aggravation Is Enough
New Jersey does not require a worker to arrive at the job in perfect health. The governing rule is that an employer is liable when employment is a material contributing cause of the disability, even if a pre-existing condition also contributed. In Dwyer v. Ford Motor Co., 36 N.J. 487 (1962), the Supreme Court confirmed that the aggravation or acceleration of a pre-existing condition by work effort is a compensable accident. A degenerative or arthritic joint that is rendered symptomatic, or pushed to the point of requiring surgery, by a work event is the textbook fact pattern.
The Appellate Division applied this directly to a degenerative joint claim in Sexton v. County of Cumberland / Cumberland Manor, 404 N.J. Super. 542 (App. Div. 2009). There, the court reaffirmed that a worker need only prove that the employment exposure or event contributed to the disability to a material degree, measured against the worker's prior non-occupational state. Pre-existing pathology that was asymptomatic or that did not prevent full-duty work does not insulate the carrier when the job tips the condition into disability.
How This Impacts Workers' Compensation Claims
For petitioners, the practical takeaway is that a documented history of arthritis, a prior knee replacement, obesity, or advancing age is not a defense to the claim. What matters is the worker's functional condition before and after the work event. Counsel should build the record around the contrast: full-duty work without restriction beforehand, and disabling symptoms, treatment, or surgery afterward. Contemporaneous medical records, treating physician opinions tying the need for surgery to the work event, and credible testimony about the change in function are the evidentiary backbone of these claims.
For employers, carriers, and third-party administrators, the lesson is that denying a knee or joint claim solely because the imaging shows degenerative change is a losing strategy. Degenerative findings are common and expected in an aging workforce; their presence does not rebut compensability. The defense burden is to show that the work event did not materially contribute, which typically requires a competing medical opinion that the disability would have progressed identically absent the workplace incident. A bare reliance on pre-existing arthritis invites an award and exposure for the cost of surgery and resulting disability.
For both sides, apportionment, not denial, is usually the real battleground. Under N.J.S.A. 34:15-12 and the Second Injury Fund framework, a worker with a prior loss of function may recover for the increase in disability attributable to the new work event, with the Fund potentially responsible where total disability results from the combination of old and new injuries. The existence of a pre-existing condition reshapes the allocation of liability rather than eliminating it.
Bottom Line
A worker who was doing the job and is now facing knee surgery after a workplace incident has a viable New Jersey claim, notwithstanding a long history of arthritis. The aggravation of a pre-existing condition is, and remains, compensable. The fight is over degree and apportionment, not over whether benefits are owed at all.
Sources
Judd v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2010 WY 85, 233 P.3d 956 (Wyo. 2010)
Dwyer v. Ford Motor Co., 36 N.J. 487 (1962)
Sexton v. County of Cumberland/Cumberland Manor, 404 N.J. Super. 542 (App. Div. 2009)
N.J.S.A. 34:15-12 (Compensation schedule)
About the Author
Jon L. Gelman of Wayne, NJ is the author of NJ Workers' Compensation Law (West-Thomson-Reuters) and co-author of Modern Workers' Compensation Law (West-Thomson-Reuters).
Blog: Workers' Compensation | LinkedIn: JonGelman | Substack: jongelman.substack.com | Blue Sky: jongelman@bsky.social
© 2026 Jon L Gelman. All rights reserved. | Attorney Advertising | Prior results do not guarantee a similar outcome.
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