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Savio L. C. Woo - One of the best experts on this subject based on the ideXlab platform.

  • biomechanical analysis of an anatomic Anterior Cruciate Ligament reconstruction
    American Journal of Sports Medicine, 2002
    Co-Authors: Masayoshi Yagi, Eric K. Wong, Akihiro Kanamori, Richard E Debski, Savio L. C. Woo
    Abstract:

    Background:The focus of most Anterior Cruciate Ligament reconstructions has been on replacing the anteromedial bundle and not the posterolateral bundle.Hypothesis:Anatomic two-bundle reconstruction restores knee kinematics more closely to normal than does single-bundle reconstruction.Study Design:Controlled laboratory study.Methods:Ten cadaveric knees were subjected to external loading conditions: 1) a 134-N Anterior tibial load and 2) a combined rotatory load of 5-N·m internal tibial torque and 10-N·m valgus torque. Resulting knee kinematics and in situ force in the Anterior Cruciate Ligament or replacement graft were determined by using a robotic/universal force-moment sensor testing system for 1) intact, 2) Anterior Cruciate Ligament deficient, 3) single-bundle reconstructed, and 4) anatomically reconstructed knees.Results:Anterior tibial translation for the anatomic reconstruction was significantly closer to that of the intact knee than was the single-bundle reconstruction. The in situ force normalize...

  • the biomechanical interdependence between the Anterior Cruciate Ligament replacement graft and the medial meniscus
    American Journal of Sports Medicine, 2001
    Co-Authors: Christos D Papageorgiou, Jorge E Gil, Akihiro Kanamori, James A Fenwick, Savio L. C. Woo
    Abstract:

    To establish a quantitative biomechanical relationship between the Anterior Cruciate Ligament graft and the medial meniscus, 10 human cadaveric knees were examined using the robotic/universal force-moment sensor testing system. In response to a combined 134-N Anterior and 200-N axial compressive tibial load, the resulting kinematics of the knee and the in situ forces in the Anterior Cruciate Ligament, the Anterior Cruciate Ligament graft, and the medial meniscus were measured. Anterior tibial translation significantly increased after Anterior Cruciate Ligament transection, between 6.8±2.3 mm at full extension and 12.6±3.3 mm at 30° of flexion. Consequently, the resultant forces on the medial meniscus, ranging from 52±30 N to 63±51 N between full extension and 90° of knee flexion in the intact knee, were doubled as a result of Anterior Cruciate Ligament deficiency. However, after Anterior Cruciate Ligament reconstruction, Anterior tibial translations were restored to the levels of the intact knee, and thus...

  • importance of the medial meniscus in the Anterior Cruciate Ligament deficient knee
    Journal of Orthopaedic Research, 2000
    Co-Authors: Christina R. Allen, Eric K. Wong, Glen A. Livesay, Masataka Sakane, Savio L. C. Woo
    Abstract:

    The incidence of meniscal tears in the chronically Anterior Cruciate Ligament-deficient knee is increased, particularly in the medial meniscus because it performs an important function in limiting knee motion. We evaluated the role of the medial meniscus in stabilizing the Anterior Cruciate Ligament-deficient knee and hypothesized that the resultant force in the meniscus is significantly elevated in the Anterior Cruciate Ligament-deficient knee. To test this hypothesis, we employed a robotic/universal force-moment sensor testing system to determine the increase in the resultant force in the human medial meniscus in response to an Anterior tibial load following transection of the Anterior Cruciate Ligament. We also measured changes in the kinematics of the knee in multiple degrees of freedom following medial meniscectomy in the Anterior Cruciate Ligament-deficient knee. In response to a 134-N Anterior tibial load, the resultant force in the medial meniscus of the Anterior Cruciate Ligament-deficient knee increased significantly compared with that in the meniscus of the intact knee; it increased by a minimum of 10.1 N (52%) at full knee extension to a maximum of 50.2 N (197%) at 60 degrees of flexion. Medial meniscectomy in the Anterior Cruciate Ligament-deficient knee also caused a significant increase in Anterior tibial translation in response to the Anterior tibial load, ranging from an increase of 2.2 mm at full knee extension to 5.8 mm at 60 degrees of flexion. Conversely, coupled internal tibial rotation in response to the load decreased significantly, ranging from a decrease of 2.5 degrees at 15 degrees of knee flexion to 4.7 degrees at 60 degrees of flexion. Our data confirm the hypothesis that the resultant force in the medial meniscus is significantly greater in the Anterior Cruciate Ligament-deficient knee than in the intact knee when the knee is subjected to Anterior tibial loads. This indicates that the demand on the medial meniscus in resisting Anterior tibial loads is increased in the Anterior Cruciate Ligament-deficient knee compared with in the intact knee, suggesting a mechanism for the increased incidence of medial meniscal tears observed in chronically Anterior Cruciate Ligament-deficient patients. The large changes in kinematics due to medial meniscectomy in the Anterior Cruciate Ligament-deficient knee confirm the important role of the medial meniscus in controlling knee stability. These findings suggest that the reduction of resultant force in the meniscus may be a further motive for reconstructing the Anterior Cruciate Ligament, with the goal of preserving meniscal integrity.

Wilson C Hayes - One of the best experts on this subject based on the ideXlab platform.

  • Anterior Cruciate Ligament graft fixation comparison of hamstring and patellar tendon grafts
    American Journal of Sports Medicine, 1994
    Co-Authors: Mark E Steiner, Aaron T Hecker, Charles H Brown, Wilson C Hayes
    Abstract:

    This study assessed the tensile properties of hamstring and patellar tendon Anterior Cruciate Ligament recon structions in older cadaveric knees (age range, 48 to 79 years). Mechanical testing to failure was conducted by translating the tibia Anteriorly at 1 mm/sec with the knee in 20° of flexion. The strongest gracilis-semitendinosus graft fixation technique (103% of intact Anterior Cruciate Ligament) had the tendons doubled and secured with soft tissue washers (P < 0.01 ). However, all reconstruc tions using gracilis-semitendinosus grafts were signifi cantly less stiff than the intact Anterior Cruciate Ligament specimens regardless of fixation technique (P< 0.01 ). The highest strength patellar tendon graft fixation tech nique (84% of intact Anterior Cruciate Ligament) was ob tained with a combination interference screw and suture technique. The difference in stiffness between a patellar tendon graft and an intact Anterior Cruciate Ligament was not significant when interference screws were placed at bot...

  • Anterior Cruciate Ligament graft fixation comparison of hamstring and patellar tendon grafts
    American Journal of Sports Medicine, 1994
    Co-Authors: Mark E Steiner, Aaron T Hecker, Charles H Brown, Wilson C Hayes
    Abstract:

    This study assessed the tensile properties of hamstring and patellar tendon Anterior Cruciate Ligament reconstructions in older cadaveric knees (age range, 48 to 79 years). Mechanical testing to failure was conducted by translating the tibia Anteriorly at 1 mm/sec with the knee in 20 degrees of flexion. The strongest gracilis-semitendinosus graft fixation technique (103% of intact Anterior Cruciate Ligament) had the tendons doubled and secured with soft tissue washers (P 0.05). Both types of grafts failed most often on the tibial side. With appropriate fixation, both grafts approximated the intact Anterior Cruciate Ligament in strength, but only patellar tendon grafts secured with interference screws were comparable in stiffness.

Gregory W Rennirt - One of the best experts on this subject based on the ideXlab platform.

  • correlation of anthropometric measurements strength Anterior Cruciate Ligament size and intercondylar notch characteristics to sex differences in Anterior Cruciate Ligament tear rates
    American Journal of Sports Medicine, 2001
    Co-Authors: Allen F Anderson, David Dome, Shiva Gautam, Mark H Awh, Gregory W Rennirt
    Abstract:

    We performed a prospective study based on the hypothesis that physiologic differences exist between men and women in strength after adjustments for body weight; that the size of the Anterior Cruciate Ligament is proportionate to the strength of its antagonists, the quadriceps muscles; and that women have a relatively small Anterior Cruciate Ligament, thus predisposing them to a disproportionate number of Anterior Cruciate Ligament injuries. One hundred matched high school basketball players, 50 male and 50 female, were evaluated with anthropometric measurements, body fat analysis, muscle strength evaluation, and magnetic resonance imaging measurements of the intercondylar notch and cross-sectional area of the Anterior Cruciate Ligament at the outlet. The male players were taller and heavier than their female counterparts, although they had 11% less body fat. Male players had statistically greater quadriceps and hamstring muscle strength than female players, even when adjustments were made for body weight. With adjustments for body weight, the size of the Anterior Cruciate Ligament in girls was found to be statistically smaller than in boys. There was no statistically significant difference in the notch width index between the sexes. The study data support our hypothesis that sex differences in Anterior Cruciate Ligament tear rates are caused primarily by several interrelated intrinsic factors. Most importantly, stiffness and muscular strength increase stress on the Anterior Cruciate Ligament in female athletes. The Anterior Cruciate Ligament, when adjustments have been made for body weight, is smaller in female athletes, and therefore, probably does not compensate for the lack of stiffness and strength.

  • correlation of anthropometric measurements strength Anterior Cruciate Ligament size and intercondylar notch characteristics to sex differences in Anterior Cruciate Ligament tear rates
    American Journal of Sports Medicine, 2001
    Co-Authors: Allen F Anderson, David Dome, Shiva Gautam, Gregory W Rennirt
    Abstract:

    We performed a prospective study based on the hypothesis that physiologic differences exist between men and women in strength after adjustments for body weight; that the size of the Anterior Cruciate Ligament is proportionate to the strength of its antagonists, the quadriceps muscles; and that women have a relatively small Anterior Cruciate Ligament, thus predisposing them to a disproportionate number of Anterior Cruciate Ligament injuries. One hundred matched high school basketball players, 50 male and 50 female, were evaluated with anthropometric measurements, body fat analysis, muscle strength evaluation, and magnetic resonance imaging measurements of the intercondylar notch and cross-sectional area of the Anterior Cruciate Ligament at the outlet. The male players were taller and heavier than their female counterparts, although they had 11% less body fat. Male players had statistically greater quadriceps and hamstring muscle strength than female players, even when adjustments were made for body weight....

Leo A Pinczewski - One of the best experts on this subject based on the ideXlab platform.

  • fifteen year outcome of endoscopic Anterior Cruciate Ligament reconstruction with patellar tendon autograft for isolated Anterior Cruciate Ligament tear
    American Journal of Sports Medicine, 2011
    Co-Authors: Catherine Hui, Lucy J Salmon, James Linklater, A Kok, Shinichi Maeno, Leo A Pinczewski
    Abstract:

    Background: Few studies report the long-term results of Anterior Cruciate Ligament rupture and single-incision endoscopic reconstructive surgery. Outcomes are often clouded by concomitant meniscal, chondral, or Ligament injuries.Purpose: To determine the 15-year outcomes of Anterior Cruciate Ligament ruptures treated with endoscopic Anterior Cruciate Ligament reconstruction using middle-third patellar tendon autograft.Study Design: Case series; Level of evidence, 4.Methods: Between January 1993 and April 1994, 333 consecutive patients underwent Anterior Cruciate Ligament reconstruction. Patients with associated Ligamentous injury requiring surgery, previous meniscectomy, or meniscal injury requiring more than one-third meniscectomy; chondral injury diagnosed at arthroscopy; and an abnormal contralateral knee were excluded. Ninety patients met the inclusion criteria. Outcomes included range of motion, Lachman and pivot-shift tests, instrumented Ligament testing, single-legged hop test, Lysholm Knee Score, ...

  • revision Anterior Cruciate Ligament reconstruction with hamstring tendon autograft 5 to 9 year follow up
    American Journal of Sports Medicine, 2006
    Co-Authors: Lucy J Salmon, Vivianne J Russell, Leo A Pinczewski, Kathryn M Refshauge
    Abstract:

    BackgroundThe results of revision Anterior Cruciate Ligament reconstruction are limited in the current literature, and no studies have previously documented the outcome of revision Anterior Cruciate Ligament reconstruction using solely hamstring tendon grafts.HypothesisRevision Anterior Cruciate Ligament reconstruction with 4-strand hamstring tendon graft affords acceptable results and is comparable to reported outcomes with the bone–patellar tendon–bone graft.Study DesignCase series; Level of evidence, 4.MethodsFifty-seven consecutive revision Anterior Cruciate Ligament reconstructions with the hamstring tendon graft and interference screw fixation were assessed a mean time of 89 months (range, 60-109 months) after surgery. Assessment included the International Knee Documentation Committee knee Ligament evaluation, instrumented laxity testing, and radiologic examination.ResultsOf the 50 knees reviewed, 5 (10%) had objective failure of the revision Anterior Cruciate Ligament reconstruction. Of the 45 pati...

  • gender differences in outcome after Anterior Cruciate Ligament reconstruction with hamstring tendon autograft
    American Journal of Sports Medicine, 2006
    Co-Authors: Lucy J Salmon, Kathryn M Refshauge, Vivianne J Russell, Justin P Roe, James Linklater, Leo A Pinczewski
    Abstract:

    BackgroundIt is now well documented that women are more likely to suffer Anterior Cruciate Ligament injuries than are men. A few studies have examined gender differences in the outcome of Anterior Cruciate Ligament reconstruction with patellar tendon graft and hamstring tendon with Endo Button fixation, but no well-controlled studies have specifically compared men and women after Anterior Cruciate Ligament reconstruction with hamstring tendon graft and interference screw fixation.HypothesisThere is no difference in outcome between men and women after Anterior Cruciate Ligament reconstruction with hamstring tendon autograft and interference screw fixation.Study DesignCohort study; Level of evidence, 3.MethodsThere were 100 men and 100 women who underwent isolated Anterior Cruciate Ligament reconstruction by a single surgeon. Patients were assessed preoperatively and at 1, 2, and 7 years after surgery. Variables were compared between female and male patients.ResultsLaxity on physical evaluation was greater ...

Thomas J Gill - One of the best experts on this subject based on the ideXlab platform.

  • the effect of Anterior Cruciate Ligament deficiency and reconstruction on the patellofemoral joint
    American Journal of Sports Medicine, 2008
    Co-Authors: Samuel K Van De Velde, Thomas J Gill, Louis E Defrate, Ramprasad Papannagari
    Abstract:

    BackgroundLittle is known about the effect of Anterior Cruciate Ligament deficiency and reconstruction on the patellofemoral joint.HypothesisAnterior Cruciate Ligament deficiency changes the patellofemoral joint biomechanics. Reconstruction of the Ligament does not restore the altered patellofemoral joint function.Study DesignControlled laboratory study.MethodsEight patients with an acute Anterior Cruciate Ligament injury in 1 knee and the contralateral side intact were included in the study. Magnetic resonance and dual-orthogonal fluoroscopic imaging techniques were used to compare the patellofemoral joint function during a single-leg lunge between the intact, the Anterior Cruciate Ligament–injured, and the Anterior Cruciate Ligament–reconstructed knee. Data on the patellar tendon apparent elongation and orientation, patellar tracking and patellofemoral cartilage contact location were collected preoperatively and at 6 months after reconstruction.ResultsAnterior Cruciate Ligament deficiency caused a signi...

  • in vivo kinematics of the knee after Anterior Cruciate Ligament reconstruction a clinical and functional evaluation
    American Journal of Sports Medicine, 2006
    Co-Authors: Ramprasad Papannagari, Thomas J Gill, Louis E Defrate, Jeremy M Moses, Alex Petruska
    Abstract:

    BackgroundRecent follow-up studies have reported a high incidence of joint degeneration in patients with Anterior Cruciate Ligament reconstruction. Abnormal kinematics after Anterior Cruciate Ligament reconstruction have been thought to contribute to the degeneration.HypothesisAnterior Cruciate Ligament reconstruction, which was designed to restore Anterior knee laxity under Anterior tibial loads, does not reproduce knee kinematics under in vivo physiological loading conditions.Study DesignControlled laboratory study.MethodsBoth knees of 7 patients with complete unilateral rupture of the Anterior Cruciate Ligament were magnetic resonance imaged, and 3D models were constructed from these images. The Anterior Cruciate Ligament of the injured knee was arthroscopically reconstructed using a bone–patellar tendon–bone autograft. Three months after surgery, the kinematics of the intact contralateral and reconstructed knees were measured using a dual-orthogonal fluoroscopic system while the subjects performed a s...

  • the effect of Anterior Cruciate Ligament reconstruction on knee joint kinematics under simulated muscle loads
    American Journal of Sports Medicine, 2005
    Co-Authors: Louis E Defrate, Ramprasad Papannagari, Jae Doo Yoo, Sang Eun Park, Thomas J Gill
    Abstract:

    BackgroundNumerous studies have investigated Anterior stability of the knee during the Anterior drawer test after Anterior Cruciate Ligament reconstruction. Few studies have evaluated Anterior Cruciate Ligament reconstruction under physiological loads.PurposeTo determine whether Anterior Cruciate Ligament reconstruction reproduced knee motion under simulated muscle loads.Study DesignControlled laboratory study.MethodsEight human cadaveric knees were tested with the Anterior Cruciate Ligament intact, transected, and reconstructed (using a bone–patellar tendon–bone graft) on a robotic testing system. Tibial translation and rotation were measured at 0 °, 15 °, 30 °, 60 °, and 90 ° of flexion under Anterior drawer loading (130 N), quadriceps muscle loading (400 N), and combined quadriceps and hamstring muscle loading (400 N and 200 N, respectively). Repeated-measures analysis of variance and the Student-Newman-Keuls test were used to detect statistically significant differences between knee states.ResultsAnte...

  • In Vivo Elongation of the Anterior Cruciate Ligament and Posterior Cruciate Ligament During Knee Flexion
    The American journal of sports medicine, 2004
    Co-Authors: Louis E Defrate, Hao Sun, Thomas J Gill
    Abstract:

    BackgroundMost knowledge regarding Cruciate Ligament function is based on in vitro experiments.PurposeTo investigate the in vivo elongation of the functional bundles of the Anterior Cruciate Ligament and posterior Cruciate Ligament during weightbearing flexion.HypothesisThe biomechanical role of functional bundles of the Anterior Cruciate Ligament and posterior Cruciate Ligament under in vivo loading is different from that measured in cadavers.Study DesignIn vivo biomechanical study.MethodsElongation of the Anterior Cruciate Ligament and posterior Cruciate Ligament was measured during a quasi-static lunge using imaging and 3-dimensional computer-modeling techniques.ResultsThe Anterior-medial bundle of the Anterior Cruciate Ligament had a relatively constant length from full extension to 90° of flexion. The posterior-lateral bundle of the Anterior Cruciate Ligament decreased in length with flexion. Both bundles of the posterior Cruciate Ligament had increased lengths with flexion.ConclusionThe data did not...

  • tibial plateau fracture following Anterior Cruciate Ligament reconstruction
    Knee Surgery Sports Traumatology Arthroscopy, 2004
    Co-Authors: Kai Mithofer, Thomas J Gill, Mark S Vrahas
    Abstract:

    A case is presented of a tibial plateau fracture after previous Anterior Cruciate Ligament reconstruction using patellar tendon autograft. The tibial plateau fracture occurred through the transosseous tibial tunnel and followed a torsional injury to the involved extremity. The stress riser effect of the transosseous tibial tunnel and the anatomic location of the cortical defect probably facilitated development of the fracture. Minimally invasive fixation of the fracture was effective in preserving knee stability without need for revision Anterior Cruciate Ligament reconstruction.