Anterior cruciate ligament reconstruction

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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.

1 Types of grafts
- 1.1 Autograft vs. Allograft
  - 1.1.1 Patellar tendon
  - 1.1.2 Hamstring tendon
- 1.2 Choice of Graft
2 Recovery
3 Footnotes
4 External links

[edit] Types of grafts

[edit] 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.

Allografts are often 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 donor grafts, a risk of infection remains and it would be cause to remove the graft. Therefore, this option runs the largest health risk.

[edit] 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 patellar tendon connects the patella (kneecap) to the tibia (shin). The graft is taken from the injured knee, but in some circumstances, such as a second operation, the other knee may be used. The middle third of the tendon is used, with bone fragments removed on each end. The graft is then threaded through holes drilled in the tibia and femur, and finally screwed into place.

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.

[edit] Hamstring tendon

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

The gracilis muscle and semitendinosus tendons, part of the hamstrings, are the graft source. A long piece (about 25 cm) is removed from each tendon. The tendon segments are folded and braided together to form a quadruple thickness strand for the replacement graft. The braided segment is threaded through the heads of tibia and femur and its ends fixated with screws on the opposite sides of the two bones.

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^{[citation needed]}.

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.

[edit] 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.

[edit] Recovery

Initial physical therapy consists of range of motion (ROM) exercises, often with the guidance of a physical therapist, to regain the flexibility and prevent scar tissue from forming, and simple exercises to reduce loss of muscle tone (for example, 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.