|September 23, 2017||0|
Knee arthroscopy is a minimally invasive technique that allows orthopaedic surgeons to assess – and in most cases, treat – a range of conditions affecting the knee joint. During the procedure, we make small incisions or portals in the affected joint, and then inserts a tiny camera and fiber optics to light the interior space. Pictures obtained with the camera are then projected onto a screen in the operating suite. The primary advantage afforded by arthroscopy is the ability to gain multiple views inside the joint. In the past, gaining access to some of these areas required an arthrotomy – a surgery in which an open incision was made – and dislocation of the patella, or “knee cap”. That procedure required additional trauma to the knee and carried the risk of additional injury to the joint. In contrast, arthroscopic examination of the knee joint usually does little damage to surrounding soft tissues. While most orthopedic surgeons continue to rely on radiographs (x-rays) and MRI to provide important preliminary information, many agree that arthroscopy is the best diagnostic tool available. Arthroscopy offers pieces of information that the other tests don’t including that which is derived by probing the affected tissue.
MRI is a wonderful tool to evaluate the structure of the soft tissues, but does not provide the tactile information acquired by probing the soft tissues and evaluating them with direct visual observation. Here at Hospital, general anaesthesia is rarely indicated for arthroscopic surgery of the knee which is generally performed with regional or occasionally local anaesthesia. Reconstruction of the ACL (anterior cruciate ligament) and repair of a torn meniscus are among the most commonly performed arthroscopic surgeries. Within the knee, these structures perform distinct functions. The ACL helps stabilize and support the joint. There are two menisci in the knee. These c-shaped “cushions” of cartilage help protect the articular cartilage, the lining of the bones that allows them to glide smoothly against one another during motion. (Injury or loss of articular cartilage results in arthritis.) These structures also act as shock absorbers, distributing load across the knee. Injuries to both the ACL and the menisci are common, particularly in athletes. Moreover, surgeons often see them in conjunction with one another. This may be the result of injuries suffered at the same time, or in sequence; that is, a person with a torn ACL is at greater risk of injuring the menisci. Statistics show that more than 60% of patients diagnosed with an ACL tear also have a torn meniscus. Some ACL and meniscus injuries can be treated non-surgically with rest, physical therapy, and activity modification. However, in a young active person, choosing to forgo ACL reconstruction or meniscus repair is likely to result in persistent instability and pain in the knee, as well as setting the stage for degenerative arthritis if they are unwilling to modify their sport-related activities significantly. Arthroscopic surgery takes place only after the immediate post-injury swelling and inflammation has diminished, and the patient has recovered almost complete range of motion.
Arthroscopic photo showing meniscus tear. When the ACL is sustains a complete tear, we replace it with a graft. Grafts can be obtained from the patient’s own knee (termed an autograft), or from donated tissue (termed an allograft, but sometimes referred to as a cadaver graft). Generally, autografts are used in the adolescent and young population of athletes, and allografts are used in the older patient population. The autograft sources include the bone-patellar tendon-bone graft, the hamstring tendon graft or the quadriceps tendon graft. When an autograft is used, it is retrieved through a small open incision. The general success rate following ACL reconstruction is 85 to 90%. In recent years the revision ACL surgery rate has increased, often as a result of recurrent injury to the knee sometime after the original surgery.
Illustration showing tear and area of resection. Recovery time from an ACL reconstruction varies, with a period from about 6 to 9 months representing an average time required before the athlete returns to collision sports. During that period the patient participates in a rehabilitation program designed to restore range of motion, strengthen muscles, and regain balance and sports-specific skills. The treatment goal for a torn meniscus is preservation of the structure. The meniscus serves a purpose – to transmit load across the joint. Depending upon the type of tear, the location of the tear, the quality of the torn fragment, and the age of the patient, repairing the meniscus is the surgeon’s priority. It has been demonstrated that when an athlete sustains a tear that cannot be (or is not) repaired, they are at increased risk for developing articular cartilage damage – early arthritis . Where possible, the we suture the torn meniscus together using one of a variety of techniques. The sutures are placed using arthroscopic techniques. When the meniscus tear cannot be repaired because of the location, tear type, poor quality of tissue, or inadequate blood supply (usually associated with the location of the tear), the meniscus is partially excised – termed a partial meniscectomy – while preserving as much of the normal structure as possible. In some cases, when the tear is complex or severe, the we remove the majority of the meniscus. In these cases, it is often appropriate to transplant an allograft meniscus from donor tissue at a later date to prevent degenerative deterioration of the joint. Illustration showing tear and area of resection. Recovery time for these surgeries varies, with an average range of 3 to 6 weeks with respect to partial meniscectomy and 12 to 16 weeks regarding meniscus repair. Patients are enrolled in a rehabilitation program during this period. In addition to ACL reconstruction and meniscus repair, arthroscopy is used for: reconstruction of other ligaments that support the knee articular cartilage regeneration, and arthritis of the knee to provide relief from symptoms of clicking or locking.