Before surgery
ACL prehab: the weeks before surgery
The two to six weeks between the tear and the operation are the cheapest weeks in the whole recovery. Here is the evidence that they matter and what to do with them.
Prehab gets treated as optional because nothing has been operated on yet and it feels like waiting. It is the opposite: the state of your knee on the morning of surgery sets the starting line for the first three months, and those three months are where the outcome is largely decided.
The evidence
A comparative effectiveness study set the MOON cohort against the Delaware-Oslo cohort, the difference being extended preoperative rehabilitation. 72% of patients who did extended preoperative rehabilitation returned to their preinjury sport, against 63% in the comparison cohort, and IKDC and KOOS scores at two years were significantly and meaningfully higher after preoperative rehabilitation. Same operation, better outcomes, from work done before anyone touched the knee.
The four targets
| Target | Why | How you know you have it |
|---|---|---|
| Full passive extension, matching the other knee | Extension lost before surgery is much harder to recover after it | Lie prone with the thigh supported and compare both heels |
| Effusion down to trace or none | Fluid in the joint inhibits the quadriceps, so swelling is a strength problem | The stroke test, graded zero to 3+ |
| A quadriceps that contracts on command | You cannot strengthen a muscle that will not switch on | A straight leg raise with no extension lag, and a hard superior pole of the patella |
| Normal gait without crutches | A limp you carry into surgery is a limp you carry out of it | Walk in a straight line and have someone watch from behind |
What prehab looks like week to week
- Days 1 to 7
Calm the joint
Compression, elevation, cryotherapy, gentle range of motion within comfort, quad sets and straight leg raises, and walking as your knee tolerates. The goal is a knee that drains and straightens, nothing more ambitious.
- Week 2
Motion and activation
Full extension work daily, flexion as it comes, patellar mobilization, quadriceps activation with the swelling coming down. Stationary bike if the knee allows it.
- Weeks 3 to 6
Actually get stronger
Leg press, controlled squats, step-ups, hamstring and hip and calf work, balance, and cardiovascular fitness. If you have weeks, use them: strength going in is strength you do not have to rebuild from zero.
Get baseline numbers before surgery
Ask for a measured quadriceps and hamstring strength value on both legs before your operation, with the units and the device. It is the only true baseline you will ever have, and it makes every symmetry number for the next year mean something.
The administrative work of these weeks
- Confirm the surgeon, the facility and the anesthesiologist are all in network. Since January 2022, out-of-network providers treating you at an in-network facility generally cannot balance bill you above your in-network cost sharing for many services including anesthesia and assistant surgeons.
- Get the prior authorization confirmed in writing, and ask what it covers.
- Ask your plan how many rehabilitation visits are authorized per plan year and when the plan year resets.
- Find out your remaining deductible and your out-of-pocket maximum today, not in the abstract. For 2026 the maximum annual limitation on cost sharing for non-grandfathered plans is $10,600 self-only and $21,200 for other than self-only coverage.
- If you are uninsured or paying cash, ask for a Good Faith Estimate in writing. You can dispute a final bill that exceeds it by $400 or more.
- Line up your physical therapy clinic and book the first appointment before surgery, not after.
- Arrange the practical things: someone to drive you home, a place to elevate the leg, ice, and time off already agreed with work or school.
What not to do
Do not spend the wait resting completely, do not chase deep flexion in a swollen knee, and do not test your knee's stability by trying to cut on it. The instability that makes an ACL tear consequential is the instability that damages the meniscus while you wait.