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PATIENT: ________________________

AGE: _______



I. What is ACI?

Autologous Chondrocyte Implantation (ACI) is a process whereby articular cartilage cells (chondrocytes) are collected, multiplied in a laboratory to increase cell number and then re-implanted with a special surgical technique into the damaged area of the knee. This would allow cell growth and cartilage repair to occur producing new, durable cartilage.

II. Immediate Post-operative Protocol

The day after the surgery, the limb will be placed on a Continuous Passive Motion Machine on a continuous or intermittent basis. Every hour, you will be required to stop the machine with the leg straight and carry out a program of contraction exercises for the thigh muscle to regain control of the knee.

You will be in the hospital for 3 days. During this time, the physiotherapist will instruct you how to go about walking with crutches wearing a straight-leg splint touching the operated foot to the ground without putting weight on the leg. The brace should be worn day and night and removed only when doing your knee curl exercises (lying on your stomach) and for showering. You will continue to do your quadriceps contraction exercises hourly, throughout waking hours, without removing the brace.

III. Post Operative Rehabilitation Protocol – Upon Discharge

Note: The post-operative regimen is a standard guide, however each patient is different and the program is modified according to the patient’s progress and capabilities.


Phase 1: Proliferative/ Protective Phase (0-6 weeks)


– protect the transplanted graft from excessive loads and shearing forces
– control pain and reduce inflammation
– gain full extension and gradual recovery of knee flexion
– regain neuromuscular control of quadriceps muscle

1. Brace
a. Keep brace locked at 0 degrees of extension during ambulation
b. Brace can be unlocked when sleeping at nights for the first 2 weeks

Weight bearing
a. non-weight bearing for the first 0-2 weeks
b. toe-touch ambulation for the following 3-4 weeks
c. partial weight-bearing for 5-6 weeks

2. For pain control and swelling
a. Cryotherapy (ice compression)
b. Compression stockings
c. Anti-inflammatory

3. ROM
a. CPM (0-40 deg) for 4-8 hours per day for the first 2 weeks then with additional increase of 5 degrees per day as tolerated
b. Full extension postural exercises (e.g. flexor’s knee muscles stretching)
c. Gentle active assisted (with controlateral leg) ROM exercises twice daily with the following objectives:
i. 60 degrees flexion after the second week
ii. 90 degrees flexion after the fourth week
iii. 120 degrees flexion after the sixth week
d. Pendolar exercise when ROM 90 deg is gained

4. Strengthening exercises (10-20 reps x 2-3 sets)
a. Quadriceps setting exercises
b. Straight leg raises with knee locked in extension
c. Gluteus, abductor and adductor hip muscles
d. Active plantar flexion-extension
e. Isometric leg press at multiple angles of flexion (0 deg – 30 deg – 60 deg – 90 deg) from week 5-6
f. Pool exercises
g. Stationary cycling without resistance once with 90 degrees of flexion (after 4 weeks)

5. Quadriceps and VMO muscle electrical stimulation as needed

6. Non weight bearing proprioceptive exercises

Note: Patellar, Trochlear and Lateral Femoral Condylar lesions remain non weight bearing for 3 weeks while Medial Femoral Condyle lesion are preferred to stay non-weight bearing for 6 weeks.


– minimum pain and swelling
– recovery of complete passive extension and flexion of approximately 120 degrees

Phase 2: Transition Phase (6-12 weeks)


– gait retraining
– increase the strength of the quadriceps and flexors
– gradual increase in functional activities

1. Brace
a. Maintain until with sufficient quadriceps strength for ambulation and during SLR exercises

Weight Bearing
a. Progress to full weight bearing and abort the use of crutches by 8-12 weeks post implantation as tolerated

2. Start gentle multidirectional patella mobilization

3. Discontinue CPM but proceed with active and passive ROM exercises

4. Strengthening exercises
a. Quadriceps and hamstring exercises
b. Hip and calf muscles exercises
c. Pool exercises
d. Stationary cycling with resistance as tolerated (may lower seat as comfort may allow)
e. SLR with brace
f. Closed kinetic chain terminal knee extension exercises (0-40 deg)

5. Quadriceps and VMO muscle electrical stimulation as needed

6. Progression from non weight bearing to weight bearing proprioceptive exercises as tolerated


– complete ROM (0-135 deg)
– approximately 70% quadriceps and flexor strength compared to contralateral limb
– absent or minimum pain and swelling

Phase 3: Graft Maturation Phase (12-24 weeks)


– further increase in quadriceps and flexor strength and resistance
– further increase in functional activities

1. Brace
a. Not needed at this stage

Weight bearing
a. full weight bearing without assistive devices as comfort would allow

2. Strengthening Exercises
a. Leg press (0-90 deg)
b. Closed chain kinetic exercises (elastic leg press, half-squats 0-60 deg)
c. Open chain kinetic exercises (elastic resistance, leg extension 90-0 degrees)
d. Leg curl (0-90 deg)
e. Step exercises

3. Continue patellar mobilization

4. Proprioception weight bearing exercises at increasing difficulty level

5. Increase Functional Activities
a. Treadmill jogging
b. Cycling on level surfaces
c. Swimming


– complete ROM (0-135 deg) without pain
– approximately 90 deg quadriceps and flexor strength compared to contralateral limb
– absence of pain and swelling

Phase 4: Functional Recovery Phase (24-52 weeks)


– gradual return to functional activities without limitations

1. Strengthening Exercises
a. Open and closed chain kinetic exercises with progressive weight bearing, pylometric exercises
b. Exercises focused at enhancing proprioception, agility, coordination as well as sport specific exercises (on field rehabilitation)

Note: Return to sport is not advised within twelve months of implantation and high impact activities should be avoided for two years. Activities requiring standing and walking can commence however, all activities such as squatting, kneeling, stair-climbing and bent knee activity should be delayed until six months from implantation, if possible.