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ACL Return to Sport

ACL reconstruction, week 0 to year 2

Your knee will feel ready months before it is ready

That gap is where second ACL injuries happen. This site is built around the numbers that close it: time since surgery, quadriceps symmetry, hop test symmetry, and confidence. Every figure here is traceable to the study it came from, and the studies disagree in places. We say where.

No sign-in, no quiz funnel, nothing you enter leaves your browser. See every source.

The four numbers that decide return to sport

Months since surgery9+
Quadriceps symmetry90%+
Hop test symmetry90%+
Effusion, stroke testzero

Delaware-Oslo cohort: reinjury fell 51% for every month return was delayed up to 9 months, and 38.2% of athletes who failed these criteria were reinjured versus 5.6% of those who passed.

Athlete progressing through return-to-sport rehabilitation after ACL reconstruction

Start here

Three questions, then read the right page

This site covers everything from the day you tear it to the day you get cleared. Tell us where you are and we will send you to the four pages that matter now, instead of the forty that do not.

Where are you right now?

Single-leg hop test measured by an athletic trainer

Evidence

What the numbers actually say

23%of athletes under 25 who return to sport sustain a second ACL injury, ipsilateral or contralateral (Wiggins 2016 meta-analysis)
51%lower reinjury rate for each month return to sport was delayed, up to 9 months (Grindem 2016)
4.1xgraft rupture risk in professional athletes who returned without meeting all six discharge criteria (Kyritsis 2016)
65%of patients return to their preinjury level of sport, 55% to competitive sport (Ardern 2014, 7,556 participants)

Those four numbers are the reason this site exists. They are also the reason we publish the counter-evidence: a 2019 meta-analysis of four studies found that passing return-to-sport criteria was not significantly associated with a lower second injury risk, at very low quality of evidence. Testing is the best tool available, not a guarantee, and anyone who tells you otherwise is selling something.

Quadriceps strength test during ACL rehabilitation

The app

What the app does

Closed beta. The waitlist is the only thing on this site that asks for an email address.

Everything on this site is a piece of one year of your life, and right now that year is scattered: the protocol on a folded sheet in your gym bag, the measurements in your physical therapist's notebook, the isokinetic report in an email, the scar photos lost in your camera roll. The app puts all of it in one place. Every day you know what to do. Every week you can see it moving. On appointment day your PT and your surgeon have the whole picture in front of them.

Your road map on day one

The six phases, what actually unlocks each one, and a real date for every milestone computed from your surgery date. Not a countdown, a plan.

Today's session

What to do today, with the cue, the load, the sets and a timer. It opens offline, because the gym in the basement has no signal.

56 guided movements

One library, three axes of progression, and a movement that unlocks on a clinical criterion rather than on a calendar date.

Same-day and next-day rating

Two questions in the evening, two more the next morning. The gap between them is the earliest honest signal that a session was too much.

Your measurements

Range of motion, thigh circumference, pain, effusion, logged in under three seconds and plotted from week one.

Strength and hop tests

Your numbers, your limb symmetry index computed for you, and the distance left to the threshold instead of a raw ratio you have to interpret.

The questionnaires

SANE from the beta, then IKDC, KOOS and ACL-RSI as licensing allows, prompted on the dates where the score actually changes a decision.

The scar, month by month

Same framing every time, side-by-side with last month, in an album that does not live in your camera roll.

The medical file

Operative report, MRI, X-rays, isokinetic PDFs, insurance letters: stored next to the rehab, not in an inbox you search at 11pm.

Appointments and paperwork

The next surgeon visit, the month to book the isokinetic test, work restrictions, short-term disability, prior authorization, and the clearance your school or league wants.

A one-page report

Printable, or shared through a link that expires. Your PT sees your curves, not your account.

Where other people were

Anonymous reference bands from people with the same graft at the same week. It appears when there is enough data to be worth reading, not before.

The app never issues a green light. It shows the criteria you have met and the ones you have not, and the decision stays with you, your physical therapist and your surgeon. That is a product rule, not a legal one: an app that clears athletes to play is a different, regulated object, and a worse one.

Health data is never sold and never used for advertising. The closed beta opens in French first, with the patient product; the English version is the next language to ship, and the waitlist is what sets that order. Pricing principle is already settled: you start for free, and when you pay, you pay once for the whole recovery instead of a subscription you will forget to cancel. Join the waitlist.

Recovery tracking app

Get told when the beta opens

We are building the thing this site keeps pointing at: a tracker that records your strength numbers, your hop tests, and your ACL-RSI over time, and shows you the gap between where you are and where the testing thresholds sit. Two emails at most before launch, unsubscribe in one click.

We ask for an email address and nothing else. No surgery date, no diagnosis, no health information. See the privacy policy.

References cited on this page

Every figure on this page comes from one of the publications below. The level of evidence is stated: a national guideline, a meta-analysis and a case series do not carry the same weight.

  • Kotsifaki R, Korakakis V, King E, et al. Aspetar clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction. British Journal of Sports Medicine, 2023;57(9):500-514. Read the publication. Clinical practice guideline built with the GRADE method: progression driven by objective criteria rather than the calendar alone, early strengthening, explicit criteria for returning to running and to sport.
  • Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. British Journal of Sports Medicine, 2016;50(13):804-808. PubMed 27162233. 106 pivoting-sport patients, prospective two-year cohort.
  • Ardern CL, Taylor NF, Feller JA, Webster KE. Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis including aspects of physical functioning and contextual factors. British Journal of Sports Medicine, 2014;48(21):1543-1552. PubMed 25157180. 69 papers, 7,556 participants.
  • Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. American Journal of Sports Medicine, 2016;44(7):1861-1876. PubMed 26772611. Systematic review and meta-analysis, 19 studies.
  • Poulsen E, Goncalves GH, Bricca A, Roos EM, Thorlund JB, Juhl CB. Knee osteoarthritis risk is increased 4-6 fold after knee injury: a systematic review and meta-analysis. British Journal of Sports Medicine, 2019;53(23):1454-1463. Read the publication. Systematic review and meta-analysis, 53 studies, close to one million participants. Knee osteoarthritis risk is 4.2 times higher after an ACL injury and 6.3 times higher after a meniscal injury, with at least two years of follow-up.

See the full bibliography

Questions people actually ask

How long until I can run again?
Most protocols open the running progression somewhere between week 12 and week 16, and the gate is not the date. It is a quiet knee with no effusion, full extension, symmetrical gait and quadriceps strength usually around 80% of the other leg. Running on a knee that fails those checks is how people spend month five going backwards. See the timeline.
Is 9 months a real threshold or a slogan?
It comes from measured cohorts. In the Delaware-Oslo cohort the reinjury rate dropped 51% for each month return was delayed up to 9 months, with no further reduction after that. In a Swedish registry study of 159 athletes aged 15 to 30, returning to knee-strenuous sport before 9 months carried a hazard ratio of 6.7 for a second ACL injury. Both are cohort studies, not randomized trials, and neither says month 9 is a light switch.
My knee feels normal at four months. Why wait?
Because feeling normal and testing normal separate early. Athletes with quadriceps asymmetry at return to sport were still unloading the operated leg on landing two years later. The knee gets quiet long before the leg gets strong, and the leg gets strong long before the movement pattern comes back.
Who writes this site?
See the about page. Short version: it is written from primary sources, each one listed with its PubMed identifier, by the company that also builds the tracker. It is not written by your physical therapist, and it is not a substitute for the person who can put their hands on your knee.