Anterior Cruciate Ligament Rehab

ACL blood supply is the middle genicular branch of the popliteal artery. Its sensory innervation is he branches of tibial, common peroneal and obturator nerves. 

Function

Resists anterior displacement of tibia on femur and external rotation of tibia. Plays a key role in proprioception. 

Injury is more common in females than males due to different landing biomechanics (more likely to collapse into valgus) and the width of the pelvis (smaller intercondylar notch and ligaments). 

History

• Common with pivoting
• Valgus and external rotation force
• Foot fixed (studded boots, attached to ski)
• Sudden deceleration
• Audible 'pop'
• Haemarthrosis

Investigation

• ADT (note: contraction of hamstrings may limit)
• Lachman's
• Pivot shift
• MRI
• Arthroscopy

Associated Injuries

• MCL and medial meniscus (forms the unhappy triad)
• Posterolateral corner
• PCL
• If the posterior capsule is ruptured, blood can seep down into the calf and give the appearance of a DVT

Grafts

• Autograft (own tissue) - e.g. Semitendinosus and gracilis
• Synthetic
• Allograft (someone else's freshly frozen Achilles' tendon). 

Graft Healing

• Phase I - (0-2 weeks) - Graft is at its strongest, fixation weakest
• Phase II - (2-6 weeks) - Graft a it's weakest
• Phase III - (6-12 weeks) - Revascularisation of graft
• Phase IV - (3-6 months) - Increasing graft strength
• Phase V - (6 months) - Graft a 30-60% of initial strength

Rehabilitation Aims

Phase I

• Protect graft during devascularisation
• Minimise inflammation (PRICE)
• Restore full terminal knee extension
• Increase ROM
• Quads control and hamstrings strength
• Promote early mobility
• Partial weight bear at first
• Possible knee brace with crutches
• Continuous passive movements (can use machine for this)
• Stairs Ax
• Proprioceptive work

Phase II

• Protect graft
• Encourage FWB
• Restore normal gait
• Increase ROM
• Retrain proprioception and prevent arthrofibrosis
• Promote functional activities for ADL
• Increase muscular strength and endurance

Phase III

• Advanced proprioceptive exercises
• Open chain exercises through range (no resistance)
• Increase muscle work and control
• Ideal isometric quad strength = 75-85%

Phase IV

• Maximal strengthening
• Rotational weight bearing activities
• Bilateral dynamic activities
• Hamstrigns 90% contralateral side ideally
• Eccentric contraction

Phase V

• Sport specific
• Preparation for complete return (physically and mentally)
• Return to sport 9-12 months (80-90% strength and proprioception)