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Twenty knee dislocations in 19 patients (one bilateral) occurred over a period of 20 years. The age range was 21 to 65 years, with an average age of 40.8 years. There were two popliteal artery and eight peroneal nerve injuries in the group. All patients were managed by early closed reduction at the scene of the accident or at the admitting hospital. Treatment consisted of 13 acute arthrotomies with complete ligamentous repair, one partial ligament repair, two delayed repairs, and four cast applications. Both anterior and posterior cruciate ligaments were torn in each knee surgically examined. In contrast to cruciate injuries in nondislocated knees, avulsion of bone of the PCL was present in 14 of 16 and of the ACL in ten of 16. Complete follow-up study including examination and radiographic evaluation was obtained on 18 knees in 17 patients. Special investigations of 13 with acute complete ligament repair, followed from 12 months to 48 months (average of 24 months), showed loss of joint motion following this injury. Clinical instability was generally not a problem, but chronic pain and discomfort were present in 46%. The average knee diagnostic score was 43. Seventy-seven percent of the patients returned to vigorous sports activities. Early operative repair followed by cast bracing and manipulation at three months (if flexion was less than 90 degrees) is recommended in young, active patients.
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PMID:Complete knee dislocation. A follow-up study of operative treatment. 402 70

Delineation of the cruciate ligaments in 112 patients using the computed tomography under arthrographic conditions was reported. Special position were used allowing for the demonstration of both cruciate ligaments in their complete lengths. In 6.2% of the examinations a reliable demonstration of the cruciates was not possible for technical reasons. Demonstration of normal cruciate ligaments in CT arthrography was described and normal values were tabulated. Recent cruciate ligament injuries were seldom examined by CT arthrography since the clinical symptoms were mostly unequivocal. The old ruptures of the ACL were divided into 4 different types: Type I: Rupture of the femoral origin that adjoins the PCL. Type II: Attenuation of the intraligamentary ruptured ligament with a preservation of origin and insertion. Type III: Complete rupture with shrinking and retraction of the fragments. Type IV: Osseous involvement of the femoral origin or tibial insertion. In 36 old cruciate ligament ruptures, the sensitivity of this method of investigation was 97%, the specificity 100%. After reconstructive surgery, CT arthrography allows for an objective analysis of the operative results and permits the comparison of different techniques of surgical repair.
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PMID:Evaluation of the cruciate ligaments by CT. 733 29

In order to evaluate the contribution of the knee ligaments to restrain joint motions, knowledge about their structural properties is required. Due to the variable relative insertion orientation of the ligaments during knee motion, however, different fiber bundles are recruited, each with their specific mechanical properties. Hence, the structural properties vary as a function of knee motion. For this reason, a relationship between the structural tensile properties and the relative insertion orientation is required in order to define the role of the ligaments in knee mechanics. In the present study, this relationship is determined by performing a series of tensile tests in which the relative orientations of the insertion sites of human knee bone-ligament-bone preparations were varied systematically. The experimentally obtained stiffness was significantly affected by the relative orientation of the insertion sites, but more profoundly for the anterior and posterior cruciate ligaments (ACL and PCL) as compared to the medial and lateral collateral ligaments (MCL and LCL). The average decreases in stiffness per 5 degrees tilt of the insertion sites were estimated at -11.6 +/- 3.5 N mm-1 (ACL), -20.9 +/- 2.7 N mm-1 (PCL), -2.6 +/- 0.9 N mm-1 (MCL) and -3.7 +/- 0.3 N mm-1 (LCL). For the PCL and the MCL these changes in stiffness with tilt were rather insensitive to the side of the femoral insertion site which was lifted. The ACL and the LCL, conversely, displayed significant differences in stiffness changes between the different tilt directions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effect of variable relative insertion orientation of human knee bone-ligament-bone complexes on the tensile stiffness. 760 74

This paper describes a novel modeling technique for simulating the motion of the knee joint in three dimensions. For a given range of flexion, the envelope of passive knee joint motion is determined by applying additional translations and rotations necessary to maintain Force Balance in the joint. An initial application of this Force Balance technique has been implemented in MATLAB on a Sparc 10. Results of this application, which describes the knee's motion in the sagittal plane based on the ACL, PCL, MCL, and LCL, are presented here. This model is applicable to the analysis of ligament loss, damage, and repair, and can be adapted to include muscle forces in order to simulate joint motion under load.
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PMID:A technique for simulating the motion of the knee in three dimensions. 765 82

This study was performed to make a normal standard by analyzing normal knee movement in detail. An open low-field unit was used for 23 healthy knee joints. With three-dimensional Fourier transformation (3DFT) gradient echo sequence, 50 sagittal slices of 4.5 mm in thickness were obtained at four flexion angles: 0, 30, 60, and 90 degrees (lateral position). Although the tension ratio of the anterior and posterior cruciate ligaments (ACL, PCL) increased during knee flexion, the change in the tension ratio was significantly different between the ACL and PCL. The femur-ACL angle and femur-PCL angle were parallel with the knee flexion angle, but the tibia-ACL angle and tibia PCL angle changed complexly. The lateral and medial condyles rolled and slid during knee flexion, and the medial side moved more than the lateral side, consistent with rotation of the lower thigh. The difference in backward movement distance on the tibia between the two condyles was significantly larger in females than in males. This might explain the dominance of knee osteoarthritis in women. Although the lateral position is not completely physiological, we could show initial cinematic data of up to 90 degrees of knee flexion using open-type MRI, which is impossible with high- and middle-field machines.
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PMID:Analysis of knee movement with low-field MR equipment--a normal volunteer study. 780 8

At the present time, our understanding of the PCL still lags behind that of the ACL. This knowledge gap has narrowed over the past few years, however, as more basic research has shed new light on the complex anatomy and functional mechanical behavior of the PCL and the nearby capsuloligamentous structures. Recent insights have included recognition that the PCL is composed of a fiber continuum rather than morphologically separate bands or bundles, a better appreciation of the predominantly nonisometric behavior of the intact PCL, and a greater awareness of the PCLs importance in preserving normal articular kinematics. Continued advances in the basic science of the PCL are a prerequisite for improvements in the treatment and rehabilitation of its injury.
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PMID:Anatomy and function of the posterior cruciate ligament. 795 79

PCL reconstruction is often a necessary procedure to regain functional knee stability. The procedures used are not able to precisely recreate normal anatomy but are able to provide functional stability to posteriorly destabilized knees when properly performed. Our arthroscopic-assisted procedure limits the soft tissue dissection required and enables the best possible visualization for accurate graft placement. This limits scarring and maximizes the ability of the surgeon to provide posterior knee stability. Allograft tissue, when used as an ACL substitute, was initially believed to be as good as autogenous tissue. It is now believed to be inferior because of slower healing and a tendency to attenuate. PCL allograft reconstructions have not been adequately studied to determine if this same tendency of graft attenuation occurs. In many knees, however, adequate autogenous tissue may not be available, and the only chance to regain stability requires using an allograft. It is in these circumstances that the authors recommend allograft reconstructions.
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PMID:Reconstruction of the posterior cruciate ligament with allograft. 795 85

In conclusion, PCL injuries occur more commonly than previously noted. The PCL-deficient knee is a serious pathology; it is one of functional disability, not functional instability as seen with an ACL disruption. This functional disability is secondary to pain and inflammation from articular cartilage degeneration. The degeneration process occurs over a period of time normally greater than 5 years; eventually knee function is seriously limited. The rehabilitation of the PCL reconstructive or nonoperative patient is greatly dependent on dynamic quadriceps stability. The biomechanics of the PCL and PLC during various exercises are not well understood; however, research is being performed to advance the clinical management following these injuries. The clinician must realize that tremendous tibiofemoral shear forces are created during various knee exercises, in both the closed and open chain. In particular, various knee exercises, in both the closed and open chain. In particular, there are tremendous stresses applied to the PCL during OKC-resisted knee flexion. The clinician must also realize the role of the hamstrings during most closed chain exercises; therefore the author recommends an early program emphasizing isolated open chain quadriceps strengthening progressing to closed chain drills once adequate quadriceps strength has been established. The numerous clinical challenges for the rehabilitation team to hurdle when treating a PCL-injured knee patient have been discussed in this article. The PCL rehabilitation program can no longer be thought of an an ACL rehabilitation program "turned around." The anatomy, biomechanics, and natural history of the PCL-deficient knee differs dramatically from the ACL-deficient knee, and the treatment approach should reflect these considerations.
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PMID:Rehabilitation of isolated and combined posterior cruciate ligament injuries. 795 89

In reconstructing the ACL, ideal tibial tunnel placement requires an understanding of the unique anatomy of the ACL tibial footprint and its relationship to the PCL, lateral meniscus, and medial tibial part of the spine. In addition to precise placement of the tibial tunnel, its length and angulation are factors to consider. Using consistent anatomic landmarks with attention to detail, the tibial tunnel can be reproducibly placed in a manner that is not detrimental to the graft.
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PMID:Tibial tunnel placement in ACL reconstruction. 800 37

Surgical reconstruction of the PCL has not yet gained the acceptance that ACL reconstruction has achieved. However, in selecting an autograft to restore PCL function in symptomatic posterior knee instability, the free patellar tendon autograft is commonly used at present. Knowledge of the basics in graft healing and of factors regulating this healing process are still limited. It is of interest to determine the biologic response and final morphology of a patellar tendon autograft after PCL replacement. Based on morphological studies in PCL replacement in a sheep model the patellar tendon autograft under-goes necrosis and degeneration followed by a gradual healing process comprising revitalization (i.e. revascularization and cellular proliferation), formation of extracellular matrix components and remodeling. The autograft bone pegs become osseointegrated by 6 weeks. After 2 years, the autograft tissue differs structurally from a ligament, suggesting that the autograft may never approach normal ligament characteristics. Degenerative alterations in the core region of the autograft, the widespread presence of type III collagen and fibronectin, as well as the predominance of thin collagen fibrils do not favor a ligamentization process. The understanding of the autograft healing process remains the prerequisite for a realistic assessment of the biologic PCL replacement and will be a baseline of studies with the goal of influencing the healing process and thus improving the clinical results.
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PMID:The patellar tendon graft for PCL reconstruction. Morphological aspects in a sheep model. 805 42


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