Arthroscopically Assisted Anterior Cruciate Ligament Reconstruction

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  • AORN JOURNAL JANUARY 1989, VOL. 49, NO 1

    Arthroscopically Assisted Anterior Cruciate Ligament Reconstruction

    Anna L. Hales, RN

    11 ligaments stabilize joints and guide joint motion, and the anterior cruciate ligament A (ACL) is no exception. Even though its

    biomechanical and physiological properties are complex, its role is simply to stabilize the knee joint by preventing forward movement and rotation of the tibia on the femur. The anatomy of the ACL and its location within the knee joint are directly related to its role. The ligament extends up from a point in front of and just lateral to the tibia1 spine and spirals back to join the femur on the posterior aspect of the medial surface of the lateral femoral condyle (Fig 1). It ranges in length from 30 to 40 mm and in width from 7 to 15 mm.

    Historical Background

    alen, a Greek anatomist, first described the ACL in 170 AD. He recognized that G ligaments are joint stabilizers and sup-

    porters.' During the next 1,600 years, this structure was largely ignored, and the first recorded treatment of a ruptured ACL was in 1850. Two patients were managed with braces, and although they recovered, they experienced some ongoing disability.2

    The first surgical repair of a torn ACL was performed in 1885 in Leeds, England. The patient was a 41-year-old miner who was injured at work. His surgery was performed 36 weeks after the injury, and in spite of the delay, it was considered a success. Eight years later, the miner described his leg as perfectly strong. He was able to work a full day, and he was able to run. His physician

    determined that his knee was capable of full extension, normal mobility, and only slightly less than normal flexion?

    Between 1917 and 1950, the ACL received much attention from orthopedists. Many reviews and discussions were published and presented. They described various techniques that borrowed and rerouted almost every structure surrounding the knee in an attempt to create a suitable substitute for the injured ACL.4 By 1950, most methods of reconstruction had been attempted. More importantly, basic principles that today govern the management of the tom ACL had been identified and established. These include early diagnosis, early treatment, and the value of examination under anesthesia in obtaining an accurate diagnosis.

    In 1950, D. H. O'Donoghue, MD, an ortho- pedic surgeon from Oklahoma City, studied a large series of ACL tears in college athletes.5 Some believe that his work, which outlined the methods of diagnosis, operative procedure, and rehabili- tation of the injured athlete, provided the

    Anna L. Hales, RN, is a nursing coordinator, orthopedics, University Hospital, London, Ontario. She has a diploma in nursing from St Joseph's Hospital School of Nursing, North Bay, Ontario.

    The author acknowledges Peter Fowler, MD, Janet Purcell PI: and Betty Rutledge for their assistance, and George Moogk, Department of Audiovisual Services, University Hospital, London, Ontario, for the illustrations.

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    anterior cruciate

    lateral meniscus

    Fig 1. The anatomy of the knee joint,

    patella

    posterior cruciate ligament

    medial meniscus

    tibia

    momentum for todays extensive interest in ACL deficiency.6

    Professional athletes have always been prey to knee injuries, but with the increasing number of amateur and weekend athletes, the incidence of torn ACLs has increased. In fact, studies show that the ACL is the most frequently torn ligament.7

    An increased awareness of sports-related trauma has accompanied the fitness boom, and modern research has enhanced knowledge of the physi- ology and biomechanics of the ACL. These factors have improved the competence of orthopedic surgeons, general practioners, coaches, and trainers in recognizing a torn ACL and the events that may cause an ACL tear.

    The objective of any treatment of a torn ACL is to restore the knee to optimum stability and function. Scientific and clinical research have provided the orthopedic surgeon with a selection

    of options. Treatment can be conservative or surgical. Surgical treatment can be intraarticular or extraarticular. A number of autogenous structures borrowed from the knee can be used alone or augmented, and prosthetic devices can be used.

    At University Hospital, London, Ontario, the torn ACL is reconstructed using autogenous tissue that routinely is augmented with a Kennedy LAD, a polypropylene braid ligament augmen- tation device. This method is based on 15 years of research in both animals and humans that has established the following principles.

    An active person who receives no treatment for an ACL deficiency may experience serious complications. Repeated giving way of the knee leads to meniscal tears and instability that hampers the integrity of support structures such as the lateral and

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    medial collateral ligaments. The eventual result is degenerative joint disease. Reha- bilitation alone generally results in these problems more frequently than surgical treatment does. Substituting a tom ACL with autogenous tissue alone has considerable shortcomings? Autografts require six months to one year for revascularization and strengthening. This establishes the desirability of an augmen- tation device to enhance the autograft and protect it from stretching or rupturing during the regenerative period. Prosthetic ligaments are mechanically attached to bone at both ends. They are subject to frequent failure and therefore are not considered successful.

    Mechanism of Injury

    ost knee ligament injuries are sports related, and soccer, football, and M basketball are the major offenders. The

    most common cause of ACL tear is a decelerating and twisting motion when an athlete attempts to abruptly stop his or her forward movement. With sudden deceleration, the quadriceps muscles contract and pull the tibia forward on the femur. The athlete may turn his or her leg at the same time. Such simultaneous anterior and rotational stresses can result in a torn ACL. Although complete disruptions can occur at any point along the length of the ligament, they most often occur in the middle. Also, the ACL can avulse from either its femoral or tibial attachment.

    Diagnosis

    s the ligament tears, the individual feels his or her knee giving way. Pain and A swelling occur almost immediately. Any

    effusion within 24 hours of injury is considered to be a hemarthrosis, and 75% of knees with an acute hemarthrosis will have a ruptured ACL.9

    The patients history is the most important factor in making a correct diagnosis. Careful notation of the events leading up to the injury will provide the most relevant information for an accurate

    diagnosis. A clinical examination of the knee is mandatory. This is most effective when done immediately after the injury wherever the incident occurred. If too much time elapses between the injury and examination, pain and spasm may affect the quality of the examination.

    A routine examination always includes the anterior drawer test, the Lachmans test, and the pivot-shift test. If the patient cannot tolerate these, an examination under anesthesia is arranged to confirm anterior cruciate tear. These tests help the physician assess the anterior displacement of the tibia on the femur. Each of these can be positive or negative to various degrees. Complete and incomplete ligament disruptions will allow abnormal movement of the knee joint. The opposite leg is routinely examined for comparison.

    Anterior drawer test. This is done with the patients knee flexed to 90 degrees. His or her hamstrings are relaxed. The physician pulls the tibial condyles forward and away from the femur. Any excessive movement is a positive indication of ACL damage.

    Lachmns test. This is done in a similar fashion to the anterior drawer test but with the knee minimally flexed. It evaluates anterior subluxation of the tibia on the femur, and a positive result suggests an ACL disruption.

    Pivot-shift test. This maneuver begins with the knee extended (Fig 2). If the anterior cruciate ligament is torn, the tibia will be dislocated anteriorly. As the physician bends the patients knee, the tibia will jerk back into alignment with the femur at 20 to 30 degrees of flexion.

    Arthroscopy plays a major role in the diagnosis of ACL lesions. It rules out or confirms a suspected ACL disruption and exposes other injuries within the knee joint, such as meniscal tears or osteochondral fractures. Arthroscopy also allows the surgeon to see the extent and location of the tear. Any meniscal surgery, either partial meniscectomy or meniscal suturing, can be performed during arthroscopy. Much reconstruc- tive surgery can be performed arthroscopically as well.

    When an ACL ruptures, its fibers are stretched beyond the limits of their elasticity. The term mop-ended best describes the appearance of the

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    Fig 2. Position and movement of the knee during the pivot- shift test.

    torn ligament. This makes primary repair of the ACL impossible; however, in many cases if the diagnosis is made close to the time of injury, sutures can be placed in a stump of the ligament. These sutures bring the torn ends of the ligament together. In theory, the approximation of these ends will preserve the proprioceptive properties of the ACL.

    If a diagnosis is not made within two weeks of injury, the stump of ligament which may have been suitable for sutures will shrink, retract, and virtually disappear. This is why early diagnosis and treatment are ideal.

    Preoperative Preparation