ACL reconstruction surgery typically takes between 1 and 2 hours from the first incision to the last stitch. Most procedures fall closer to the 90-minute mark. The total time you’ll spend at the surgical center is longer, though, once you factor in pre-operative prep and post-anesthesia recovery. Plan on being at the facility for roughly 4 to 6 hours overall, even though the surgery itself is a fraction of that.
What Happens During the Procedure
ACL reconstruction is performed arthroscopically, meaning the surgeon works through a few small incisions rather than opening up the entire knee. A tiny camera goes into one incision so the surgeon can see the joint on a monitor, and instruments go through the others. The torn ligament is removed and replaced with a graft, which is a piece of tendon taken either from your own body (usually the patellar tendon or hamstring) or from a donor.
The surgeon drills small tunnels into the thighbone and shinbone, threads the graft through, and secures it in place with screws or other fixation devices. Over the following months, your body grows new bone around the graft, anchoring it permanently. The choice of graft type can slightly affect operating time, but the difference is usually only 15 to 30 minutes. If the surgeon also needs to repair a torn meniscus or other cartilage damage discovered during the procedure, that can add another 30 to 60 minutes.
Time Before and After the Operating Room
You’ll typically need to stop eating and drinking at midnight the night before surgery to prepare for anesthesia. On the day of the procedure, expect to arrive 1 to 2 hours early. During that window, you’ll change into a gown, have an IV placed, answer medical history questions, and speak briefly with both the anesthesiologist and surgeon. Some patients receive a nerve block before going into the operating room, which numbs the knee area and significantly reduces pain in the hours after surgery.
After the procedure, you’ll spend 1 to 2 hours in a recovery room as the anesthesia wears off. Nurses will monitor your vitals, check that you can keep fluids down, and make sure your pain is manageable. ACL reconstruction is almost always an outpatient surgery, so you go home the same day. You will need someone to drive you.
Why Some Surgeries Take Longer
Several factors can push the procedure past the typical 1 to 2 hour window:
- Additional knee damage. Meniscus tears, cartilage injuries, or damage to other ligaments discovered during surgery require extra repair time.
- Graft harvesting. Using your own tissue (an autograft) adds a step the surgeon doesn’t need with donor tissue. Patellar tendon grafts in particular require careful removal of a small bone block from each end.
- Revision surgery. If you’re having a second ACL reconstruction because a previous graft failed, the procedure is more complex. The surgeon may need to remove old hardware, address bone loss in the tunnels, and position the new graft differently.
- Patient anatomy. Larger or more muscular knees can make positioning instruments more challenging, adding modest time.
The First Few Days After Surgery
Most people are surprised by how quickly they’re up and moving. You’ll likely be encouraged to put weight on the operated leg within a day or two, using crutches for support. If you also had a meniscus repair, your surgeon may restrict how much you can bend the knee and bear weight, sometimes limiting you to 90 degrees of flexion initially. A knee brace is standard for the first several weeks.
Swelling and pain peak around 48 to 72 hours after the procedure. Ice, elevation, and prescribed pain medication help manage this phase. Most people can handle light desk work from home within a few days, though jobs requiring standing or physical activity will need more time off.
Full Recovery Timeline
The surgery itself is the shortest part of the process. Recovery follows a well-established schedule, though individual timelines vary based on graft type, additional repairs, and how consistently you follow your rehabilitation program.
During the first two weeks, the focus is on controlling swelling, regaining the ability to fully straighten your knee, and activating the quadriceps muscle. Physical therapy usually starts within the first week. By 4 to 6 weeks, most people are walking without crutches and driving again (assuming the surgery was on the left knee, or the right knee has recovered enough to brake safely).
Light jogging typically begins around 3 to 4 months. Return to cutting, pivoting, and sport-specific drills happens around 6 months, though many surgeons and physical therapists recommend waiting 9 months to a full year before returning to competitive sports. Studies consistently show that athletes who wait at least 9 months before returning to play have lower rates of re-tearing the graft. The graft needs time to fully incorporate into the bone and regain tensile strength, a biological process that can’t be rushed regardless of how strong the knee feels.
Outpatient vs. Overnight Stay
The vast majority of ACL reconstructions are outpatient, meaning you leave the surgical center the same day. An overnight stay is uncommon but can happen if you have a reaction to anesthesia, difficulty managing pain, or if additional procedures were performed alongside the reconstruction. Some patients who live far from the surgical center or who don’t have adequate help at home may also be kept overnight as a precaution. Packing comfortable, loose-fitting clothes that fit easily over a knee brace or bandages makes the trip home more manageable.