Anterior Cruciate Ligament
- Mechanism of injury: usually occurs through a twisting force being applied to the knee whilst the foot is firmly planted on the ground or upon landing. A torn ACL can also result from a direct blow to the knee, usually the outside, as may occur during a football or rugby tackle. This injury is sometimes seen in combination with a medial meniscus tear and MCL injury, which is termed O’Donohue’s triad.
- Examination:
a) Lachman test: with patient’s knee bent 20-30 degrees, grasp limb over distal femur and proximal tibia. Tibia alternately pulled forward and pushed backward. Movement of 5mm or more than that in normal limb indicates rupture of ACL
b) Anterior drawer test: With patient lying on the table, hip flexed 45 degrees, knee 90 degrees. Examiner sits on patient’s foot to stabilise it, places hands on each side of upper calf and firmly pulls tibia forward. Movement of 5mm or more is positive result. Result is compared with normal limb which is tested first.
Surgery (involves reconstruction or repair of the ACL)
- Prognosis: About 60% of patients return to the full level of pre-injury activity. But 80 – 90% have favourable results (reduced pain, good knee function and stability, and return to normal levels of activity). Surgery is usually successful for cases of ACL avulsion, where the ligament has torn away from the femur or tibia. Between 3% and 10% of people who have ACL surgery still have knee pain and instability and may need another surgery (revision ACL reconstruction). Revision ACL reconstruction is generally not as successful as the initial ACL reconstruction.
- Complications:
• Problems related to the surgery itself: Numbness in the surgical scar area, infection in the surgical incisions, damage to structures, nerves (common peroneal and tibial), or blood vessels around and in the knee, blood clots in the leg and anaesthesia risks.
• Problems with the graft tendon (loosening, stretching, reinjury, or scar tissue). The screws that attach the graft to the leg bones may cause problems and require removal.
• Limited range of motion, usually at the extremes, e.g. not being to completely bend or straighten the leg. This is uncommon, and sometimes manipulation under anesthesia can help.
• Crepitus, as the patella moves against the lower end of the thighbone (femur), which may develop in people who did not have it before surgery. In rare cases, the kneecap may be fractured while the graft is being taken during surgery or from a fall onto the knee soon after surgery.
• Pain, when kneeling, at the site where the tendon graft was taken from the patellar tendon or at the site on the lower leg bone (tibia) where a hamstring or patellar tendon graft is attached.
• Repeat injury to the graft (just like the original ligament). Repeat surgery is more complicated and less successful than the first surgery.
http://www.webmd.com/a-to-z-guides/anterior-cruciate-ligament-acl-surgery
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