Surgical Procedure
The fundamental rational for ACL reconstruction
surgery is chronic knee instability, which can lead to progressive menisci
damage and joint osteoarthrosis (4). If a patient with an ACL rupture wishes
to continue intense activity, reconstruction is advised. Obviously, older
patients may elect to forgo ACL surgery. To diagnose a torn ACL the Lachman's
test is performed. In the Lachman's test, the surgeon compares the anterior
tibial displacement of the injured and normal knee. This examination determines
knee instability and anterior cruciate ligament laxity. If the ACL is torn
the surgeon will delay surgery until knee swelling has subsided. ACL reconstruction
is a very stepwise procedure involving extremely detailed and precise surgical
"carpentry". The type of graft is decided on by the physician prior
to the surgery.
Arthroscopic ACL Reconstruction
The following will demonstrate an ACL reconstruction using a patellar tendon graft.
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Once in the operating room, the physician again tests the knee for instability using the Lachman's test. A tourniquet is placed above the knee as to control intra-articular bleeding. ACL reconstruction utilizes an arthroscope, a small probing camera that can be placed in the knee joint through a small hole. The arthroscope also contains a constant water supply that not only provides fluid pressure to make the knee joint more visible, but also acts as a filter system that removes blood and tissue debris. First the physician performs a diagnostic arthroscopic examination of the knee to make sure of the ACL is torn and to check for a torn meniscus. At this point, attention is moved to harvesting the patellar tendon graft. Incisions are made at the inferior pole of the patella and at the tibial tubercle. The middle third of the patellar tendon, roughly 12 mm wide, is taken including approximately 14 mm sections of bone on both ends of the graft. The graft is then prepared, sized and striped of any excess tissue. Going back inside the knee, the ruptured ACL is removed and the area is cleaned using a motorized device called a shaver. In some patients the femoral "notch" is narrow and may even cause the ligament to tear. Therefore, a notchplasty is performed to widen this femoral intercondylar space (4). After the femoral intercondylar notch is cleaned, the knee is ready for the tibial and femoral guide tunnels to be drilled. The tibial guide tunnel is started just medially to the tibial tubercle, and a needle is pushed into the joint space. The guide is positioned to barely "kiss" the anterior part of the PCL (6). The tibial tunnel is then drilled to fit the graft. The guide is then passed through the tibial tunnel to position it for drilling the femoral tunnel. Much care must be taken to best restore the original anatomy of the ligament and find the isometric position in the knee (the point where the ACL is not stretch in knee flexion or extension) (6). After the guide wire is positioned correctly, the femoral tunnel is drilled. Once the tibial and femoral tunnels are drilled they are inspected, smoothed and clean so that the graft can then be placed. The graft is then placed through the tibia, through the knee joint, and into the femoral drill hole. For the graft to heal, blood vessels must grow into the reconstructed ACL. To hold the graft in place, a bioabsorbable screws are inserted into the tibial and femoral drill holes. At this point the reconstruction is complete. |
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Home --- Knee
Anatomy --- How Knee Injuries Occur
--- Gender Differences --- Types
of ACL Grafts --- Surgical Procedure
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