ACL Injury and Reconstruction

Progression after ACL reconstruction should depend on measured strength symmetry and movement control, not on weeks elapsed. Two patients at the same point after surgery can be at completely different stages of readiness, and treating them by the calendar is how re-rupture happens.

We test rather than estimate: limb symmetry index for quadriceps and hamstring strength, hop test battery, and landing mechanics.

First, restore full extension and reduce swelling — extension lost early is difficult to recover. Then quadriceps activation, which is inhibited after surgery and does not return simply through use. Then progressive strengthening, then plyometrics and landing control, then change of direction, then sport-specific work.

Full extension and quadriceps activation come first because later phases build on them, and lost extension has a long tail: in 502 patients followed for at least ten years after reconstruction, lack of normal extension was the factor most strongly linked to lower self-reported knee scores 4. They are unglamorous and they are the part most often rushed.

Clearance is given on test results, and typically not before nine months 1. Returning earlier is associated with substantially higher re-injury rates, and the difference between nine months and six is not a matter of caution — it is a matter of measured risk.

We give the numbers rather than an opinion, and if a player wants to return before meeting the criteria we document that decision rather than endorse it.

Return to sport after reconstruction carries a substantially raised risk of a second ACL injury, to the reconstructed knee or the other one: in pooled studies, 23% of athletes under 25 who went back to their sport had one 5. In one cohort, the re-injury rate fell with each month that return was delayed up to nine months after surgery, and was lower when quadriceps strength was close to that of the other leg 1; whether passing a full test battery lowers it further is not yet clear 6.

This belongs to the athlete rather than to us, and it has to be presented as a trade-off rather than as encouragement. A criteria-based report gives someone under pressure from a coach or a club something to hold up.

It depends on the knee and on when the decision is made. For a recent tear in young, active adults, a Cochrane review found one randomised trial: reconstruction followed by rehabilitation gave similar self-reported knee function at two and five years to rehabilitation alone with the option of later surgery, although 51% of the rehabilitation group had opted for reconstruction because of instability by five years 2. The review rated that evidence as low quality.

The picture changes for a knee that keeps giving way months after the injury. In a UK trial of 316 people with a non-acute tear and persistent instability, reconstruction gave better knee scores at 18 months than rehabilitation, and 41% of those allocated to rehabilitation went on to have the operation 3. Instability and the sport a person wants to return to decide it, not the scan alone.