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During the last few years, major advances have been achieved in our understanding and treatment of chronic instability of the knee joint. The central hub (ACL and PCL) is the most important stabilizing element, and its rupture usually results in slipping knee, pain and recurrent hydrarthrosis, which are particularly frequent and severe in athletes. However, in some circumstances the loss of the anterior cruciate ligament can be compensated for by other stabilizing elements or by an excellent musculature. In patients with slipping knee, clinical, radiological and even arthroscopic examinations are necessary to decide on the treatment to be applied. This treatment depends on the importance and type of laxity, on the presence or absence of meniscal and cartilaginous lesions, on the degree of functional impairment and on the patient's life style. Several methods can be used, from rehabilitation alone to the replacement of the deficient ligament(s) by autografts or artificial ligaments. Treatment should not be stereotyped, and only specialist can determine the best method for each individual patient.
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PMID:[Chronic instability of the knee]. 260 78

PCL injuries are major injuries of the knee. Most of the literature on PCL injury has focused on mechanism of injury, diagnosis, and treatment. We are presenting a review of the anatomy of the PCL. Different portions of the PCL are taut at different degrees of knee flexion and extension. The PCL, thus, along with the ACL, contributes to the "screwhome mechanism" of the knee. The anatomy of the meniscofemoral ligaments (ligaments of Wrisberg and Humphrey) reveals the intimate relationship among the PCL, the popliteus muscle, and the lateral meniscus. Understanding the anatomy of the PCL is important in the diagnosis and treatment of ligamentous injuries and also in total knee arthroplasty.
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PMID:Anatomy of the posterior cruciate ligament. A review. 264 73

A prospective study was performed on 50 patients who were thought or suspected to have cruciate ligament tears. Each patient had a clinical examination preoperatively and under anesthesia and instrumented examination using the MedMetric KT-1000 arthrometer, Stryker knee laxity tester, and Genucom knee analysis. The diagnosis was confirmed by arthrotomy or arthroscopy. Thirty had acute knee injuries (within 2 weeks), 9 had subacute (2 weeks to 3 months), and 11 had chronic injuries. The surgical findings demonstrated that five had other maladies, but no cruciate ligament tears. Two had a partial ACL tear, and the remaining 43 patients had at least one cruciate tear. The preoperative clinical examination for cruciate ligament integrity was completely correct in 92%, correct but incomplete in 6%, and incorrect in 2%. Examination under anesthesia was correct in 98%, the KT-1000 was correct in 75% (involved knee minus noninvolved knee was greater than or equal to 3 mm laxity equal to ACL tear), the Stryker was correct in 75%, and Genucom in 70%. The average laxity of those with ACL tears was 4.4 mm with the KT-1000, 4.6 mm with the Stryker, and 2.0 mm with the Genucom. The methods of testing with the Stryker and the KT-1000 are similar and the laxity recorded in patients with a torn ACL were almost identical. However, the KT-1000 can be used to identify the quadriceps neutral position and therefore more accurately determine PCL instability. The Genucom has the most versatility, but the laxity recorded in patients with a torn ACL was significantly lower than the other devices.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Preoperative instrumented testing of anterior and posterior knee laxity. 272 89

Computed tomography (CT) with arthrography, a method not requiring anesthesia, has worked well in cruciate ligament damage diagnosis, particularly in the detection of PCL damage and in differentiation between ACL and PCL lesions. Evidence has been produced of its superior accuracy by comparison, in the study of 40 patients, among clinical findings, findings obtained from initial radiography, and diagnostic data produced by CT alone. Reference is also made to false interpretations in the context of clinical examination and CT.
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PMID:Noninvasive diagnosis of cruciate ligament damage with particular reference to computed tomography with arthrography. 278 34

Magnetic resonance imaging (MRI) is an accepted non-invasive modality for evaluation of soft tissue pathology without exposure to ionizing radiation. Current applications demonstrate excellent visualization of the anatomy and pathology of various organs. Preliminary studies in the knee reveal fine resolution of anatomy and pathology involving the meniscus. The purpose of this study is to determine a prospective correlation between MRI scans and actual meniscal pathology as documented at the time of arthroscopy. MRI scans were obtained in 155 patients, on 156 knees (one patient with bilateral scans), with 86 patients (87 knees) eventually undergoing diagnostic and operative videoarthroscopy performed by the same surgeon (DWJ). All images were obtained on the same high-resolution 1.5 Tesla GE Signa Magnetic Resonance Scanner with the same radiologist performing all readings (PEB). The knees were studied in the coronal and sagittal plane using a spin echo sequence and 5 mm slice thicknesses. The menisci were described as having Grade 1, 2, or 3 changes, with Grade 3 reserved for complete tears. Using arthroscopy as the diagnostic standard, the accuracy of MRI in diagnosing medial and lateral meniscal tears was 93.1% and 96.6%, respectively with a Grade 3 MRI reading. For tears of the ACL, the accuracy was 96.6% as confirmed at arthroscopy. Five tears of the PCL were also documented by MRI and correlated with clinical evaluation. Other abnormalities seen were articular cartilage and osteochondral defects, bone tumors, tibial plateau fractures, Baker's cysts, and meniscal cysts. The MRI scan is a highly accurate, noninvasive modality for documentation of meniscal pathology as well as cruciate ligament tears in the knee.
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PMID:Magnetic resonance imaging of the knee. 334 77

Over a 10 year period, 24 of 54 acute PCL tears in cases of straight medial instability demonstrated an absent or an equivocal posterior drawer test. Most of these (22, 91.6%) were contact injuries, and in the 11 cases where the mechanism of injury was known (45.8%), were incurred by a blow to the outer aspect of the leg while the foot was planted. The ACL was normal in 6 of the 24 knees. The abduction stress test at 0 degree extension was severely positive (2+ or more) in 21 of the 24 knees (87.5%). The phenomenon of an absent or equivocal posterior drawer test in the situation of acute straight medial instability is felt to occur when the mechanism of injury does not stress, strain, or tear the arcuate complex. If the PCL tear is not discovered and repaired, repeated stressful activity stretches the arcuate complex, and the chronically unstable knee subsequently presents with a positive posterior drawer test.
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PMID:The absent posterior drawer test in some acute posterior cruciate ligament tears of the knee. 334 78

Tensions generated in selected bands of the four major ligaments of the flexed knee (40-90 degrees) have been measured in vitro when the tibia is subjected to passive anterior translation and axial rotation with and without a compressive preload. The measurements were made in 30 fresh-frozen specimens using the buckle transducer attached to the anteromedial band of the anterior cruciate ligament [ACL (am)], the posterior fibres of the posterior cruciate ligament [PCL (pf)], the superficial fibres of the medial collateral ligament [MCL (sf)], and in the total lateral collateral ligament (LCL). Particular attention was placed on the evaluation of the performance of the transducer specific to such measurements in order to minimize the errors associated with the use of this transducer. The results indicate that, among the measured ligaments, substantial tension (greater than 20 N) is generated only in the ACL (am) in tibial anterior translation up to 5 mm. The tension pattern generated in response to tibial axial rotation, however, is complex and exhibits considerable variation between specimens. In general, both the MCL (sf) and LCL are tensed at all tested flexion angles, with the tension in external rotation being significantly greater than in internal rotation. At 40 degrees of flexion, the ACL (am) bears tension mainly in internal rotation, while at 90 degrees of flexion the PCL (pf) is tensed in both senses of rotation. The response of the LCL shows marked variation among specimens; very small tension (less than 15 N) is generated in internal rotation in 48% of the specimens, and in either sense of rotation in 20% of the specimens. The tension in the ACL (am) in internal rotation is invariably greater in those specimens in which LCL tension is negligible. This correlation between increased ACL (am) function and inadequate LCL restraint appears significant in terms of ACL injury and repair.
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PMID:In-vitro ligament tension pattern in the flexed knee in passive loading. 357 91

The fascicle material properties in bone-fascicle-bone units were determined for the anterior and posterior cruciate ligaments (ACL, PCL), the lateral collateral ligament (LCL) and the patellar tendon (PT) from three young human donor knees. Groups of fascicles from each tissue were isolated with intact bone ends and failed at a high strain rate in a saline bath at 37 degrees C. In each knee tested the load related material properties (linear modulus, maximum stress and energy density to maximum stress) for the patellar tendon were significantly larger than corresponding values for the cruciate and collateral ligaments. Bundles from different ligaments in the same knee were similar to each other in their mechanical behavior. In addition, no significant differences were present in the maximum strains recorded for any of the four tissue types examined. The results presented have implications in studies of ligament injury. They are also important in the design and use of synthetic and biological ligament replacements and in tissue and whole knee modeling.
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PMID:Comparison of material properties in fascicle-bone units from human patellar tendon and knee ligaments. 374 19

Eleven acutely injured knees and 13 normal knees were examined by magnetic resonance imaging (MRI) to assess the value of this modality in detecting acute ligamentous injury of the knee. The presence of torn ligaments in the injured knees was determined by arthroscopy and/or arthrotomy in ten cases and clinical follow-up in one case. The anterior and posterior cruciate ligaments (ACL and PCL) were demonstrated by sagittal spin echo (SE) images through the intercondylar notch (TE = 30 ms; TR = 2,000 ms). The tibial and fibular collateral ligaments (TCL and FCL) were evaluated on coronal SE images (TE = 30 ms, TR = 200 or 530 ms; TE = 120 ms, TR = 2,000 or 2,120 ms). The ACL and PCL were considered torn on MR if they appeared disrupted or were not seen in their normal anatomical positions. The collateral ligaments were considered torn if abnormal high-intensity signal was noted in adjacent soft tissues on TE = 120 ms images or if disruption of a ligament was apparent. Eleven of 15 torn ligaments and 80 of 81 normal ligaments were correctly identified by these criteria. It is concluded that MR imaging may be useful in detecting acute injury of ligaments of the knee.
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PMID:Acute injury of the ligaments of the knee: magnetic resonance evaluation. 396 76

A computer graphics technique was employed to investigate the ligament constraints in the knee joint. A computer-assisted tomography scan system was employed to obtain the geometry of the knee and the ligament insertion locations. A cadaver knee was mounted in a special rig that kept the femur and the tibia in a specified position. The scans of the knee at 5-mm distances were recorded. These scans were projected in the computer to generate a data base for the tibia, the femur, and the tibial and femoral insertion locations for the various ligaments. The computer graphics analysis provides realistic views of the bone structures. The views compare favorably with the original CT scans. Interestingly, the scans near the ligament insertion site were clearly observed to have a higher bone density. Higher density was also observed at the intercondylar notch below the patella. The analysis was used to simulate ACL and PCL insufficiencies. A Lachman test at 25 degrees of flexion is a sensitive test for ACL insufficiency, whereas the 90 degrees drawer test may not be a sensitive indicator of PCL insufficiency. This computer graphics technique may prove useful in the design and development of artificial ligaments as well as in planning surgical procedures.
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PMID:Computer-assisted analysis of ligament constraints in the knee. 399 34


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