Clinical Importance of Biokinetics through the Means of Physical Therapy

An Anterior Cruciate Ligament (ACL) injury, whether treated surgically (ACL reconstruction) or non-operatively (rehab-focused), requires progressive and individualized physical therapy to:

1. Restore Knee Stability and Function:

The ACL is a primary stabilizer, preventing anterior tibial translation and rotational instability.
Without proper rehabilitation, compensations and instability persist.

2. Prevent Secondary Joint Damage:

Poor control post-ACL injury increases the risk of meniscal or cartilage injury.
Rehabilitation improves mechanics and reduces the risk of post-traumatic osteoarthritis.

3. Re-establish Neuromuscular Control:

ACL injury affects muscle recruitment, especially of the hamstrings, glutes, and quadriceps.
Re-training is essential to avoid reinjury, particularly during cutting or pivoting tasks.

The Importance of Physical Therapy

ACL rehabilitation should follow a criteria-based progression, emphasizing range, strength, neuromuscular control, and gradual return to sport. Below are clinically relevant rehabilitation phases:

Phase 1: Early Recovery

Focus: Protect the graft, reduce pain/swelling, restore early mobility.

Phase 2: ROM & Weight Bearing

Focus: Achieve full extension, improve flexion, activate key muscles, progress to full weight-bearing.

Phase 3: Strength & Neuromuscular Control

Focus: Restore muscle strength and dynamic joint stability.

Phase 4: Advanced Strengthening & Functional Training

Focus: Restore full movement patterns, simulate sport-specific demands.

Phase 5: Return to Sport

Focus: Restore confidence, speed, and sport-specific readiness.

Safe Range of Motion (ROM)

ROM depends on the tear location and surgical intervention:

Week 1–2

0° extension (priority), 90° flexion

Week 3–4

Full extension, flexion to 120°+

Week 6–8

Near full ROM (0–135°), progressing to full as tolerated

Note: Full extension early is essential to avoid long-term gait abnormalities and quad inhibition.

Clinical Considerations

Protect the graft in early weeks, especially avoid open-chain knee extension (40–0°) too early.
Monitor for quad lag and initiate NMES or biofeedback if needed.
Caution with hamstring loading in hamstring grafts until 10–12 weeks post-op.
Psychological readiness is often overlooked; consider using tools like the ACL-RSI scale before sport return.

Summary

ACL rehabilitation must be progressive, individualised, and criterion-driven. The priorities are:

Early full extension
Gradual strength recovery (especially quadriceps)
Proprioceptive and neuromuscular retraining
Safe, controlled return to dynamic activity and sport

Focus on quadriceps activation, safe closed-chain loading, progressive mobility, and proprioceptive retraining, with ROM tailored to the injury/surgical procedure.