Before you go back to cutting or pivoting sport, do this self-test. Stand on your involved leg, drop off a 30 cm box, land on the same leg in a half squat, and hold for 2 seconds. Watch in a mirror or film your phone. If your knee collapses inward, your trunk leans, or you cannot stick the landing, you are not ready. Hop-distance symmetry alone is not enough.
A leg recovering from a serious knee injury is like a guitar string that you tuned by feel instead of with a tuner. Side-to-side it sounds fine. Play it at speed and the pitch wobbles. Hop-distance symmetry is tuning by feel. Drop-jump biomechanics and reactive strength are the tuner.
Treatment hierarchy. Tier 1 first, with the exercise prescription tied to each.
Stage 1 bilateral low-amplitude → Stage 2 bilateral high-amplitude → Stage 3 unilateral → Stage 4 multi-plane → Stage 5 sport-specific. Gate progression on quad symmetry, pain-free running, hop battery, and drop-jump quality. Not the calendar.
Buckthorpe 2022 (PMID 34903114) framework + Davies 2006 (PMID 16715831) physiological basis. Logerstedt 2015 (PMID 25682164/25724802) showed only 16-17% of ACLR patients met criterion-based gates at 8 months post-op.
Run them together. Plyometric biases the stretch-shortening cycle and reactive qualities; strength biases force production. Substituting one for the other under-doses the side you skip.
Hewett-class meta 2024 (PMID 37897637 N=1396): plyometric g=0.27 max strength vs strength training g=1.07; combined captures both.
Below this floor, the moderator analysis for sprint and jump gains does not cross statistical threshold. Stopping at week 4-6 is exposure, not training.
Ramirez-Campillo 2020 (PMID 32915430 N=1499): 10m sprint benefit only crosses threshold >7 wk and >14 sessions (between-group p=0.038). Lepley 2016 (PMID 26797700) used 8 wk / 16 visits in ACLR.
Hop LSI ≥90% AND drop-jump biomechanics symmetric AND RSI within 90% AND quad strength symmetry ≥90% AND psychological readiness AND secondary prevention in place. All five, not any one of five.
King 2021 (PMID 33560866 N=993 male athletes): sagittal-plane drop-jump deficits AUC 0.74-0.80 for contralateral ACL injury; LSI did not discriminate. Read 2023 (PMID 37523420): RSI deficits persist post-comprehensive-rehab. Wellsandt 2018 (PMID 29602303): hop symmetry is gameable.
5. Supervised SAPP-class block (strength + agility + plyometric + secondary prevention). 10 sessions over 5 wk. ACL-SPORTS RCT (Capin 2018 PMID 29924719). Perturbation add-on no incremental benefit (White 2020 PMID 32741328).
6. Tendinopathy late-stage plyometric as Stage 4 of HSR/PTLE. Apply Silbernagel pain-monitoring rule (≤5/10 during, ≤5/10 next-day, settling 24h). Cross-ref eccentric-loading-tendon-rehab.
7. Five-stage progression class as the framework over unstructured exposure. Davies 2006 + Myer 2011 [cite-unverified] field standards but stages largely RCT-unvalidated at the criterion level.
8. UE plyometric drills for post-stabilization and throwing return. Reinold/Wilk 2002 (PMID 12061709) interval-program standard. Trial-level data sparse.
If any of these are present, do not start a plyometric block. Get assessed first.
Refer: orthopedic surgeon for mechanical or structural concerns; GP for systemic concerns; sports medicine physician for ambiguous return-to-sport disputes.
All boxes ticked, not most. Time post-injury is not on this list for a reason.
Per-endpoint:
What would change this: A multi-site RCT (N≥300 post-ACLR athletes) comparing biomechanics-based RTS clearance (drop-jump sagittal-plane criteria + RSI thresholds + hop LSI) versus LSI-only clearance, with 24-month re-injury rates as primary endpoint. A clinically meaningful reduction in the biomechanics arm would upgrade drop-jump screening to HIGH and explicitly debunk LSI-only RTS.
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