Arthroscopic anterior cruciate ligament (ACL) reconstruction (right knee). The tendon of the semitendinosus muscle was prelevated, folded and used as an autograft (1). It appears through the remnant of the injured original ACL (3). The autograft then courses upwardly and backwardly in front of the posterior cruciate ligament (2).

Grafts are inserted through a tunnel that is drilled through the shin bone (tibia) and thigh bone (femur). The graft is then pulled through the tunnel and fixated with screws. The two bright objects in this X-ray are screws in the thigh bone (above) and shin bone (below).

Anterior cruciate ligament reconstruction (ACL reconstruction) is a surgical tissue graft replacement of the anterior cruciate ligament, located in the knee, to restore its function after anterior cruciate ligament injury. The torn ligament is removed from the knee before the graft is inserted. The surgery is performed arthroscopically.

Types of grafts

Autograft vs. Allograft

• An autograft involves the medical grafting of bone or tissue from the patient's body.
• An allograft is the use of bone or tissue from a donor's (typically a cadaver's) body.

The patellar tendon, anterior tibialis tendon, or Achilles tendon may be harvested from a cadaver and used as an allograft in reconstruction. The Achilles tendon, due to its large size, must be shaved to fit within the joint cavity. There is a slight chance of rejection, which would lead to another surgery to remove the graft and replace it again.

Sterilization processes exist today that make allografts a safe choice for patients. However, with allografts that are irradiated to remove infectious agents, there is a risk of weakening the selected tendon, although for ACL surgery the weakened tendon is generally as strong as the replaced ligament. ^[1] Even with the extensive and redundant screening process for irradiated donor grafts, a risk of infection remains and it would be cause to remove the graft. Therefore, the option to use an irradiated allograft runs the largest health risk.

Patellar tendon

Knees following ACL reconstruction surgery. A patellar tendon graft was used. Discoloration of the left leg is from swelling that drained from the knee to the shin.

The graft is slightly larger than a hamstring graft, however graft size is not a determinant of outcome. The most important factor in determining the outcome is correct graft placement.

The disadvantages include: 1. Increased wound pain. 2. Increased scar formation as compared to a hamstring tendon operation. 3. Risk of fracturing the patella during harvesting of the graft. 4. Increased risk of tendinitis.

Hamstring tendon

Left knee following hamstring autograft ACL reconstruction, partial meniscectomy and medial meniscus repair.

Unlike the patellar tendon, the hamstring tendon's fixation to the bone can be affected by motion in the post-operative phase. Therefore, following surgery, a brace is often used to immobilize the knee for one to two weeks while the most critical healing takes place. Evidence suggests that the hamstring tendon graft does just as well, or nearly as well, as the patellar tendon graft in the long-term.

The main surgical wound is over the upper proximal tibia, avoiding the typical pain sensation when one kneels down. The wound is typically smaller than the patellar tendon graft and hence less pain after the operation. Patients are typically discharged from the hospital within two days after surgery.

Choice of Graft

No ideal graft site for ACL reconstruction exists, they all have advantages and disadvantages. Patella tendon grafts are still considered the historical "gold standard" for knee stability by surgeons, however they suffer a slightly higher complication rate. Hamstring grafts had initial problems with fixation slippage. Modern fixation methods of hamstrings avoid graft slippage, producing outcomes that are the same in terms of knee stability with easier rehabilitation, less anterior knee pain and less joint stiffness. The main factors in knee stability are correct graft placement by the surgeon and treatment of other menisco-ligament injuries in the knee, rather than choice of graft.

Recovery

Initial physical therapy consists of range of motion (ROM) exercises, often with the guidance of a physical therapist. ROM exercises are used to regain the flexibility of the ligament, prevent scar tissue from forming and reduce loss of muscle tone. ROM exercise examples include: quadriceps contractions and straight leg raises. In some cases, a continuous passive motion (CPM) device is used immediately after surgery to help with flexibility. The preferred method of preventing muscle loss is isometric exercises that put zero strain on the knee. Knee extension within two weeks is important with many rehab guidelines.

Approximately six weeks is required for the bone to attach to the graft. However, the patient can typically walk on their own and perform simple physical tasks prior to this with caution, relying on the surgical fixation of the graft until true healing (graft attachment to bone) has taken place. At this stage the first round of physical therapy can begin. This usually consists of careful exercises to regain flexibility and small amounts of strength. One of the more important benchmarks in recovery is the twelve weeks post-surgery period. After this, the patient can typically begin a more aggressive regimen of exercises involving stress on the knee, and increasing resistance. Jogging may be incorporated as well.

After four months, more intense activities such as running are possible without risk. After five months, light ball work may commence as the ligament is nearly regenerated. After six months, the reconstructed ACL is generally at full strength (ligament tissue has fully regrown), and the patient may return to activities involving cutting and twisting if a brace is worn. Recovery varies highly from case to case, and sometimes resumption of stressful activities may take a year or longer.

The reconstructed ACL has a high success rate. Studies show that cases in which the ACL retears are generally caused by a traumatic impact. Statistically, it does not appear to matter if the patient uses a brace after recovery. A sufficiently traumatic impact to retear the ACL is unlikely to be mitigated by the use of a brace.

Recovery Progression

Recovery is a four phase progression.

Phase 1 (0-2 weeks)

The goals of this phase are to:

• Eliminate swelling due to activity
• Progress from partial weight bearing to full weight bearing exercises
• Regain normal range of motion
• Increase quadriceps strength
• Increase hamstring strength

Some equipment that can be used and exercises that can be performed are:

• Use of Cryo-cuff

- provides cold compression

• Isometric Contraction of Quads

• Quad Sets

- stand against wall, push extended knee against rolled towel

- progress to straight leg raised to 30deg.

• Wall Slides

- To increase knee flexion

• Assisted Knee Flexion

• Towel Squeeze

- Sit in chair, squeeze rolled towel between knees for 5 seconds. Relax & repeat.

• VMO Strengthening Exercise

• Supported Bilateral Calf-Raises

Phase 2 (2-12 weeks)

The goals of this phase are to:

• Regain full knee extension
• Restore knee flexion to +130°
• Perform a full squat properly
• Regain good balance and control
• Reestablish proper gait

Some exercises that can be performed are:

• Mini squats

- Progress to full squats ? single-leg half squat

• Mini Lunges

- Progress to full lunges

• Leg Press

- Double-leg ? single

• Step-ups

- lateral & forward

• Bridges

- Double-leg ? single

- Floor ? Swiss ball

• Hip Abduction w/ Theraband

• Hip Extension w/ Theraband

• Wobble board

- Assisted ? un-assisted ? eyes closed (assisted ? unassisted)

• Stork Stand

- Assisted ? un-assisted ? eyes closed (assisted ? unassisted) ? unstable surface

• Static Proprioceptive hold/ball throwing

• Functional Exercises that can be performed at this time include:

- Walking

- Bike

Phase 3 (3-6 months)

The goals of this phase are to:

• Regain full range of motion
• Regain full strength and power
• Increase agility

allows for adaption to direction change, acceleration and deceleration

• Be able to perform restricted sports-specific drills
• Begin plyomteric drills

Some exercises that can be performed are:

• Continue exercises from Phase 2, progress as necessary

• Jump & Land drills

- Jump from block & stick landing

- Double-leg landing ? single-leg

• Plyometric Drills

- Jumping over blocks, sideways & forward

- Hopping up & down steps/stairs

Phase 4 (6-12 months)

The goal of this phase is a return to activity, however it requires an ability to perform some functional performance tests such as:

• Agility Tests

• Illinois Agility Test

• Zig Zag Agility Test

These tests are used to test the ability of the knee to withstand cutting and planting maneuvers

• Standing Vertical Jump

Here you jump straight in the air from a standing start and land on two feet as stable as possible.

• Heiden Hop Test

Here you essentially jump as far as possible with the uninjured leg and land on the injured leg. Your ability to stick the landing is indicative of good knee function.

• Isokinetic Testing

This is used to evaluate muscle strength.

The individual should have at least 90% quadricep strength of the uninjured leg

They should also have equal hamstring strength to their uninjured leg as well

References

External links

• Anterior Cruciate Ligament (ACL) Reconstruction - The KNEEguru
• Dawn Hastreiter, ACL Reconstruction, University of Washington, UWMC Roosevelt Clinic, Musculoskeletal Radiology.
• ACL and Computer Aided ACL Reconstruction Presentation
• Anterior Cruciate Ligament (ACL) Graft Options
• ACL Reconstruction video
• Arthrosopic Surgery ACL Reconstruction Video
• Information for patients - Anterior Cruciate Ligament Reconstruction - Oxford Clinic
• Patient's comprehensive guide to the ACL - Illinois Sports Medicine and Orthopaedic Center
• ACL Post-Surgery Blog