In the American workers' compensation system, MMI stands for maximum medical improvement. An injured worker has reached MMI when doctors conclude that the worker's condition has improved as much as it can. However, MMI does not mean the worker has recovered or is ready to go back to work.
Workers' Comp Basics
Workers' compensation provides income to employees who have been injured or sickened on the job and cannot work. The exact rules differ by state, but in general, employers buy workers' comp coverage from an insurance company, and the insurer pays benefits to injured workers while they recover and undergo medical treatment. There is no legal definition of what constitutes maximum medical improvement for any particular injury or illness. It is a medical opinion based on the facts of each individual case.
MMI Doesn't Mean Able to Work
Reaching maximum medical improvement does not necessarily mean that an employee is able to work again. It just means that doctors believe the worker's condition is not going to improve any further. Some employees make a full recovery. They've reached MMI in the best sense of the term. But others will be left permanently disabled. A person can be paralyzed from the neck down, for example, and if her doctors conclude that her condition will not improve, then she, too, has reached MMI.
What comes after an employee reaches MMI depends on multiple factors, including the extent of any remaining disability, whether the employee can return to work and the state where the employee lives. In the best-case scenario, the employee goes back to work and the matter is closed. If partial or total disability remains, the worker may reach a settlement with the insurer or continue to receive benefits, depending on state law. State law also governs the extent of the benefits that can be paid.
Just as reaching MMI doesn't necessarily mean someone is 100 percent recovered, it also doesn't mean that a worker will no longer require medical treatment. Workers may need continuing therapy to keep their condition from deteriorating. The party responsible for paying for that care depends on state law and the contract between the employer and the insurer. If a worker's condition worsens after MMI, the worker's doctors may revise their estimate of the extent of the worker's disability, which could affect future benefits paid.