Knee Rehabilitation After Ligament Reconstruction (ACL/PCL)
Knee rehabilitation protocols after anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) reconstruction: post-operative phases, progressive muscle strengthening, neuromuscular reprogramming and return-to-sport criteria.
Presentation
Knee ligament reconstruction — surgical rebuilding of the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) — is one of the most common orthopedic procedures, particularly in athletes. Post-operative rehabilitation is a determining factor in surgical success: it conditions the quality of graft healing (patellar tendon, hamstring, or allograft), recovery of mobility, muscular strength and functional stability.
Modern protocols favor early and accelerated rehabilitation based on current scientific evidence, while respecting the biological timelines of graft ligamentization (6 to 12 months depending on graft type). Complete rehabilitation typically spans 6 to 9 months for ACL and 9 to 12 months for PCL.
Fundamental Principles
- Graft healing respect: the neo-ligament undergoes phases of avascular necrosis, revascularization, collagen remodeling and maturation
- Quadriceps deficit management: arthrogenic quadriceps inhibition is the main functional obstacle; early quadriceps strengthening is a priority
- Agonist-antagonist balance: the hamstring/quadriceps ratio (H/Q ratio) must be restored
- Proprioception and neuromuscular control: joint control reprogramming is essential to prevent re-rupture
- Objective progression criteria: phase advancement is based on measurable functional criteria, not solely on time elapsed
Rehabilitation Phases
Phase 1 — Immediate post-operative (D0 to W6): Pain and swelling control, full extension recovery (target 0° by W2), progressive flexion (90° at W4, 120° at W6), quadriceps activation (isometrics, NMES), walking with crutches and progressive weight-bearing.
Phase 2 — Mobility and strengthening (W6 to W12): Full flexion recovery, closed kinetic chain strengthening, progressive eccentric work, stationary cycling, proprioception training.
Phase 3 — Functional strengthening (W12 to M6): Open kinetic chain exercises, progressive plyometrics, treadmill running (starting W16-W20), agility and direction changes, isokinetic testing at M4-M5.
Phase 4 — Return to sport (M6 to M9+): Sport-specific re-athleticization, functional return-to-sport tests (hop tests, Y-Balance test), final isokinetic testing (criteria: quadriceps symmetry ≥ 90%, H/Q ratio ≥ 60%).
Main Indications
- ACL reconstruction (patellar tendon, hamstring, or allograft)
- Isolated or combined PCL reconstruction
- Multi-ligament knee reconstruction
- Meniscal repair combined with ligament reconstruction
- Ligamentoplasty revision surgery
- Conservative treatment of severe knee sprains
Contraindications and Precautions
- Significant joint effusion (sign of excessive loading — reduce intensity)
- Pain above 5/10 on VAS during exercises
- Signs of post-operative complications (infection, cyclops syndrome, arthrofibrosis)
- Open chain extension exercises before W12 (excessive graft strain)
- Running before W16 minimum
- Return to pivot-contact sports before M9 without validated functional tests
Medical Disclaimer
The information presented in this article is provided for educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment prescription. If in doubt, always consult your physician or a qualified healthcare professional. The techniques described do not replace conventional medical treatment.