الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The knee is one of the frequently injured joints because of its anatomical structure, exposure to external forces, and the functional demands placed on it. The stability of the knee joint depends on bones, muscles and ligaments. The cruciate ligaments are a pair of very strong ligaments connecting tibia to femur. They are indispensable to the AP stability of the knee, backward displacement of the tibia on the femur is prevented by The PCL. The PCL is twice as strong as the ACL. It contains a larger cross-sectional area and possesses a higher tensile strength. It has an average length of 38 mm and an average width of 13 mm. Its tibial attachment is to a depression behind the intra-articular upper surface of the tibia, its femoral attachment to the lateral surface of the medial femoral condyle and extends up onto the anterior part of the roof of the intercondylar notch . The ligament consists of a long, thick anterolateral fiber system and a shorter posteromedial fiber system. The ALB tightens in flexion whilst the PMB is tight in extension of the knee, The PCL may be accompanied by two ligaments; The anterior MFL (of humphrey) passes over the front of the PCL, Behind the PCL the posterior MFL (of wrisberg) descends to the posterior horn of the lateral meniscus. Its major vascular supply is the (MGA), it is supplied by nerve fibers from the popliteal plexus. Biomechanical investigations have provided us with an improved understanding of the pathomechanics of the PCL-deficient knee. It has been shown that PCL deficiency has both acute and long-term implications for knee function. At time zero, posterior tibial translations, in situ forces in the popliteus complex, and joint contact pressures all increase substantially, thereby predisposing the joint to degenerative articular changes, meniscal tears, and an increase in knee laxity over time. Biomechanical studies have also advanced markedly our understanding of the synergistic relationship between the PCL and PLS, revealing that the adverse effects of PCL deficiency are magnified even further if there is an associated injury of the PLS. To compare the results of operative and non operative treatment, one must first know the natural history of the injury. The natural history of isolated PCL tears is relatively benign. The authors concluded that most athletes with isolated PCL injuries who are able to maintain quadriceps strength are able to successfully return to sports without surgery. In contrast to isolated PCL injuries, there has been considerable agreement in the literature that combined ligamentous injuries fair poorly with conservative treatment and that degenerative changes noted on radiographs were more common in patients with combined instability patterns than in those with isolated PCL injuries. PCL tears have historically been underdiagnosed because they are often asymptomatic. It now appears that PCL tears occur more frequently than has been previously appreciated, accounting for one fifth or more of all knee ligament injuries, The rate may be higher because acute tears often go undiagnosed. More than one half of PCL injuries occur through traffic and industrial accidents, and less than one half occur through sports related injuries. The most common mechanisms of PCL injury typically involves one of the following events: A posteriorly directed force on the anterior aspect of the flexed knee as the dashboard striking the knee in a motor vehicle accident, The second mechanism is a fall on to the flexed knee, A common mechanism of injury is a posteriorly directed force applied to a fully hyperextended knee or Hyperflexion alone, The PCL is sometimes torn when an athlete is running and suddenly decelerates, And with Rotational injuries with associated varus or valgus stress. The PCL tears are classified into 3 grades according to the posterior tibial subluxation as follows: Grade I - Posterior tibial subluxation of 1-5 mm on the posterior drawer test. Grade II - Posterior subluxation of 5-10 mm. Grade III - Posterior subluxation greater than 10 mm. To diagnose a PCL deficient knee, The most reliable, and informative means remains the history and physical examination, Careful history taking is an essential part of evaluating the patient with a PCL injury. In acute isolated PCL injuries to the knee the patient usually present with a mild to moderate effusion with anterior and posterior soreness. In chronic PCL Insufficiency the main symptoms are pain or instability, pain over the posterolateral aspect of the knee In cases of acute PLRI, patients with chronic PLRI may describe pain localized along the lateral joint line. The physical examination begin by observing gait and checking static weight-bearing alignment, The skin is assessed for signs of external trauma, tenderness at the dorsal aspect of the knee, then doing the special tests such as; posterior drawer test, posterior sagging of the knee, quadriceps active test, and others. There are many types of investigations to diagnose PCL deficiency; X-rays, MRI, arthroscopy, but the MRI is the preferred examination for evaluating PCL injuries. MRI is the most sensitive and widely used modality for evaluating the PCL and the other cartilaginous and ligamentous structures of the knee, it should be obtained in all patients with suspected PCL tears because of the high incidence of injury to other structures of the knee, such as the ACL, MCL, lateral collateral ligament (LCL), and menisci. In treatment of a PCL deficient knee, the general consensus has been that isolated PCL tears do well when treated non surgically and that multiple ligament injuries about the knee should be surgically stabilized. With the advent of arthroscopic techniques has substantially reduced surgical morbidity from this procedure, permitting reconstruction as a single-day procedure and allowing for an earlier and more aggressive rehabilitation program. Non operative treatment is currently recommend for the acute isolated PCL injury grade (1 or 2), for the chronic isolated PCL injury that is newly diagnosed and has had no prior rehabilitation therapy, and for the acute or chronic isolated PCL injury or combined PCL injury in a patient who is either noncompliant or incapable of complying with the post operative rehabilitation course. Operative treatment is generally considered for acute injury with grade 3 or for multiple ligament injuries. In chronic situation, the symptomatic grade 3 posterior knee instability or multiple ligament injury and osseous avulsion injuries is considered an appropriate indication for the need of surgical intervention. The goals of operative treatment of the PCL injuries include restoration of normal tibiofemoral stability and kinematics, return to pre-injury levels of activity without pain or instability, and reduction in the likelihood or severity of long term osteoarthrosis of the knee. A variety of techniques for PCL reconstruction have been proposed and tested such as tunneling or inlay techniques (single-bundle or double-bundle) using autograft, allograft as (quadriceps tendon graft, hamstring tendon graft, Patellar tendon bone graft), prosthetic ligament and graft with prosthetic augmentation, and many fixation methods as staples, endobutton, screw used as a post, interferrence fixation, biodegradable interferrence screw, And newely Transtibial tubercle fixation without hardware for ACL and PCL reconstruction. The decision whether to use single anterolateral replacement or double-bundle reconstruction depends on the pathology in each patient. A double bundle is preferred if there is no former PCL tissue remaining, such as during revisional procedures or when the initially treating institution removed the PCL, But it is a highly vascularized and proprioceptive structure so the surgeon should try to preserve as much of the PCL tissue as possible during reconstruction. The double tunnel technique appears at this time to provide reconstruction most similar in function and anatomy to that of the natural PCL. The most common method (traditional) of PCL replacement uses a transtibial tunnel in which the graft must pass around an acute angle at the posterior aspect of the tibia. The high local tissue stresses experienced by the graft as it passes around the acute angle can cause graft thinning and permanent elongation, which in turn is expressed in increased posterior knee laxity. Loss of graft pretension because of friction at this corner, potentially high local tissue strains because of the severe bend, and non anatomic graft orientation are all possible explanations for the failure of this procedure to restore posterior laxity in clinical settings. The tibial inlay technique, described by many authors is an alternative reconstruction methods that may avoid some of the potential problems encountered when using the standard transtibial tunnel technique. This technique involves performing a posterior arthrotomy (can be done totally arthroscopic.) and creating a small bone recess in the posterior tibia at the anatomic insertion site of the PCL. The previous choice of the graft in the inlay technique was patellar tendon autograft. But due to its disadvantages, the use of the quadriceps tendon autografts in PCL reconstruction has replaced it. The essential step in reaching a good result is An adequate after-treatment. By neutralizing of posterior gravity loads with the use of a PTS splint and careful mobilization of the knee joint is performed by a physiotherapist while the patient is in the prone position.