Rehabilitation after ACL reconstruction: a phased approach and what to watch for

The new ligament is made from a graft, which has to be protected while it settles into the knee, yet the knee also needs to move and the leg muscles need to work or they waste. Rehabilitation is the process of balancing those two demands. Early on, protection and movement take priority; later, strength and control; last, the demands of running, changing direction and sport.

No national page retrieved for this guide gives a standard week-by-week timetable, and protocols differ between surgeons and between graft types. This guide therefore describes the order of the stages and leaves timings to your own leaflet. If your physiotherapist and a general website disagree, the physiotherapist knows your knee.

The first stage is about settling the knee after surgery. The usual goals are controlling swelling and pain, regaining the ability to straighten the knee fully, starting gentle bending, and waking up the thigh muscles. You may be given crutches and told how much weight to put through the leg.

The NHS arthroscopy guidance, which covers keyhole surgery in general, advises ice for 20 minutes every 2 to 3 hours, keeping the leg raised when sitting and wearing a compression stocking if one was given. Those principles are commonly applied after knee surgery, though your ACL instructions take precedence.

Once swelling has settled and the knee moves freely, the focus shifts to building strength in the thigh and hip and improving balance and walking pattern. Exercises become progressively harder, for example moving from supported to unsupported weight-bearing tasks, and from two legs to one.

This is also the period in which hospitals discharge you from the ward-based plan and ask you to continue independently or with outpatient physiotherapy. Doing the programme regularly makes a bigger difference than any single session, and a physiotherapist can adjust it if the knee swells or feels unstable.

Late-stage work usually includes controlled landing, change of direction and sport-specific drills, and often a set of tests comparing the operated and non-operated legs. Many teams use these tests, rather than the date alone, to decide when to clear someone to return.

The site has a separate guide on returning to sport after ACL surgery, which covers readiness testing and re-injury risk in more detail. The key point for this guide is that being ready for the gym, being ready for jogging and being ready for a contact sport are different decisions, and your team should say which one you have reached.

The NHS describes a small number of complications of ACL surgery. They are useful to know because several of them show up during rehabilitation rather than at the time of the operation.

• Blood clots in the leg, which the NHS says are possible because of how blood flows and clots after surgery.

• A small chance of wound infection, which can be treated with antibiotics.

• Damage to blood vessels, nerves or ligaments during surgery, which usually repairs or improves.

• Knee problems, including instability when standing or walking, persistent pain and stiffness, reduced range of movement, or problems at the graft donor site.

The NHS advises an urgent GP appointment or a call to NHS 111 if you have throbbing or cramping pain in the leg, a high temperature or alternately hot and cold sensations, oozing or pus from the wound, or tenderness, swelling, pain or redness in the knee that is getting worse or not improving.

It advises calling 999 or going to A&E if you have leg pain and swelling together with difficulty breathing or chest pain, because these can signal a blood clot in the lung.

ACL rehabilitation runs for a long time, and adherence is the usual difficulty. A few habits tend to help.

• Ask for the protocol in writing, including what each stage is meant to achieve.

• Keep a simple note of swelling and pain after sessions, so you can show the trend.

• Raise stiffness or a knee that will not fully straighten early, since it is easier to address in the first weeks.

• Agree with your employer or coach how any return to duties or training will be phased.