You didn't mention your age but since you are still working, we will assume you are younger than the average adult having a knee replacement. The peak age range for patients having total knee replacement (TKR) is 75 to 84 years old. Many patients having the unicompartmental knee arthroplasty (UKA) are younger than that.
Time in the operating room for a UKA is about an hour shorter than for a TKR. Recovery time is less for UKA, both in the immediate post-operative period and for rehab afterwards.
A recent study of outcomes suggests that patients experience about five weeks of disutility after a UKA. Disutility is defined as less than perfect health. This time period may vary depending on the age of the patient and general condition or fitness before the operation. Any complications such as infection or implant loosening can alter this estimate.
The demands of your job may make a difference as to how soon you can return to work. For example, manual laborers may need more time to rehab and build up enough strength for the required tasks compared to someone with a sedentary job at a desk. You may be able to return to your job before attaining perfect health.
Check with your surgeon for a more accurate idea. He or she may have some additional information to offer based on the type of implant being used and clinical examination of your condition.