ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Injury to the anterior cruciate ligament (ACL) of the knee is common in both recreational and competitive athletes. Complete tears of the ACL do not heal, therefore surgeons have turned to autografts and allografts in an attempt to recreate the function of the intact ACL. Choice of graft material and graft-fixation device are highly debated topics. This article provides a brief description of some basic bio-mechanical principles followed by a discussion of the application of these concepts to the evaluation of various ACL replacement grafts and ACL graft-fixation devices. The functional behavior of normal, ACL-deficient, and ACL-reconstructed knees under various external loading conditions is also discussed. The information presented in this article should provide an understanding of biomechanical factors that can aid surgeons in choosing the appropriate graft and graft-fixation construct for their patients.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

The fixation of soft tissue grafts used in anterior cruciate ligament reconstruction (ACL) is a determining factor for the long-term success of the ACL reconstruction. This article provides an overview of the mechanical test methods used in our laboratory and the biomechanics literature to compare methods of soft tissue fixation that are available to the practicing orthopaedic surgeon. The basics of uniaxial tensile testing are reviewed with particular attention to the differences between the structural properties of the reconstructed graft and the material properties of the graft itself. The effects of the stiffness of individual components on the overall structural response of the system are studied in the context of a simple series spring model. Techniques used to measure graft cross-sectional area, overall elongation, and graft strain are reviewed. The importance of controlling temperature and hydration during and between tests is emphasized. Failure testing, cyclic loading, andin vitroevaluation of joint kinematics are reviewed with specific attention to factors that affect the overall test results. The final section provides a brief overview of the factors that contribute to a well-designed experiment and statistical analysis. It is hoped that the information in this article will provide the reader with the information necessary to critically evaluate the multitude of experimental studies that compare the mechanical characteristics of different ligament fixation techniques.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Many reconstructive procedures require healing of a tendon graft in a bone tunnel (for example, reconstruction of the anterior cruciate ligament [ACL]) or to the surface of bone (for example, rotator cuff tendon repair). Tendons and ligaments attach to bone by one of two methods: a fibrocartilaginous interface (direct insertion) or by Sharpey's fibers (indirect insertion). Basic science studies have demonstrated that tendon-to-bone healing can occur by formation of either a direct or an indirect insertion, most likely because of differences in species examined, local mechanical environment, and intra-articular versus extra-articular location. Healing occurs by ingrowth of bone and soft tissue into the interface zone that forms between the tendon and bone. Recent studies have demonstrated the potential to enhance tendon-to-bone healing using cytokines such as bone morphogenetic proteins. Augmentation techniques may be especially useful in clinical situations in which healing between tendon and bone may be impaired, such as may occur in the setting of excessive motion at the graft-tunnel interface; in bone tunnel enlargement such as may be encountered during revision cruciate ligament reconstruction; or during rotator cuff tendon healing in elderly patients with osteoporosis. This article also discusses some of the fundamental questions that remain unanswered about the basic biologic and biomechanical characteristics of devices currently used for fixation of tendon grafts into bone tunnels or to the surface of bone.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Interference fixation for anterior cruciate ligament reconstruction is a common technique and can be used for patellar tendon and hamstring autografts and allografts. Bioabsorbable materials offer several advantages over metal interference screws. This study examines the in vivo histology of one biodegradable interference screw (PLLA) and reports the long-term clinical outcome of the same screw in a randomized, prospective study. The histology was investigated in a series of adult sheep undergoing patellar tendon autografts secured by either Bioscrew (PLLA) or metal interference screws. Nineteen sheep were radiologically and histologically assessed at intervals up to nearly 4 years. In the human clinical trial, a prospective randomized study was conducted of patellar tendon autografts also secured by either Bioscrew or metal interference screws. With an average follow up of 35 months (range, 24–65 months), Lachman's, pivot shift, Lysholm, Tegner, KT, motion, and radiographic evaluations were made. None of these variables showed a statistically significant difference between groups. No radiographic evidence of lytic change or bone resorption around the Bioscrews was observed in either human or sheep studies. No complications related to the bioabsorbable material (PLLA) occurred. We conclude that the Bioscrew is comparable to metal screw fixation and is safe and effective for interference graft fixation.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

For a knee ligament to be reconstructed successfully so that it is supportive through a full range of motion, it must be placed in a near-isometric or “physiometric” position. The most appropriate placement for the anterior cruciate ligament is a central tibial attachment site and a femoral attachment site high and to the extreme back of the intercondylar notch. The posterior cruciate ligament (PCL) is not an isometric ligament, but functions as at least two ligaments, an anterolateral band, which resists posterior tibial displacement when the knee is flexed, and a posteromedial band, which resists posterior tibial displacement when the knee is near full extension. When one graft is used for the posterior cruciate ligament, the anterolateral band is most appropriately reconstructed. For an anterolateral band PCL reconstruction, the tibial attachment point is near the distal-most and lateral-most fibers within the anatomic footprint, and the optimal femoral attachment point is in the anterior and distal-most aspect of the anatomic footprint. Techniques have been developed to reconstruct both the anterolateral and posteromedial bundles of the PCL. Appropriate tensioning of ligament grafts is dictated by the laxity of the normal knee and depends on the isometricity of attachment points and the biomechanical characteristics of the graft tissue and fixation devices being used.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Deciding which fixation device is the “best” depends on a number of variables. Some of them are under the control of the surgeon; some of them are under the patient's control; and others are uncontrollable. Therefore, the best fixation device is the one chosen by a knowledgeable surgeon and an informed patient. Together, they make the proper selection. No fixation device is infallible. All devices bring to the operating suite some morbidity during insertion, retrieval, or revision.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

A number of devices and techniques have been developed for fixation of soft tissue to cortical bone. This article summarizes the various aspects of soft tissue fixation techniques currently available to the orthopaedic surgeon.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

There is no doubt that complications will be with us as long as surgery is performed. However, many reported complications of anterior cruciate ligament (ACL) surgery are, in fact, errors in surgical or rehabilitation techniques. Greater awareness of the “pitfalls” associated with ACL surgery and of the “tips” to avoid them leads to improved surgical outcomes. What follows are some observations regarding problems associated with ACL reconstruction. They represent the authors' opinions and are intended only for discussion among qualified practitioners of surgical reconstructions of the human knee.

ISSN:0885-9698    

出版商:OVID    

年代:1999

数据来源: OVID