Isometry testing for anterior cruciate ligament reconstruction revisited

The purpose of this study was to determine the effect, if any, that varying the distal testing position (tibial level) has on isometry data produced with a common anatomic proximal testing position at the native anterior cruciate ligament (ACL) origin. During ACL reconstruction in 25 knees, in vivo isometry measurements were recorded using two different isometry testing methods, which differed in the tibial level of the distal fixation testing point. Method 1 tested distally at a point 13 cm peripheral to the native aCL insertion on a vector in line with the tibial tunnel. Method 2 tested distally at a point central in the native ACL insertion at the level of the intercondylar floor. All tibial tunnels were standardized with similar sagittal tunnel-plateau angles and similar tunnel lengths. The proximal testing point was standardized at a point that was anatomically located at or near the central ACL origin 7 mm anterior to “over the top” in all knees. Using these methods, length changes between the proximal and distal testing points were recorded in each knee with each testing method, with the knee ranged from 70° of flexion to full extension and from 70° to 140° of flexion. From these data, a total excursion from 0° to 140° of flexion was calculated. A nonanatomic distal testing point (Method 1) produced a 6 mm ± 1 mm total excursion, whereas anatomic testing points (Method 2) in the same knees produced a 1 mm ± 1 mm total excursion. From these data, the authors conclude that the tibial level of the distal isometry testing point has a significant effect on the resultant isometry measurement such that anatomic testing points are most isometric. Isometers that produce data between nonanatomic testing points should not be used to position tunnels for ACL reconstruction and should not be used to assume the elongation forces an ACL substitute will see when fixed at different points. Conversely, the clinical relevance of this study is that both anatomic graft position and anatomic graft fixation position are important and, when achieved, should result in minimal graft elongation with early postoperative range of motion, leading to a more stable long-term result.     

The anterior cruciate ligament

Our knowledge of the anterior cruciate ligament has expanded rapidly over the last decade. Recent advances in arthroscopic techniques, the development and release of synthetic stents and prostheses, increasing laboratory and clinical data involving allograft implantation, and biomechanical research in knee rehabilitation have led to a bewildering array of choices for treatment of anterior cruciate ligament deficiency. As new information and techniques are presented, and new synthetic and biological materials become available, orthopedic surgeons must judge their value and modify treatment recommendations accordingly. A thorough knowledge of the basic science and clinical information is necessary to appropriately evaluate these new advances. A review of our current knowledge of the anterior cruciate ligament is presented to facilitate this evaluation process.     

Arthroscopic anterior cruciate ligament repair: preliminary results and instrumented testing for anterior stability

The authors present their preliminary results of arthroscopic primary repair of anterior cruciate ligament tears performed on five patients, with a mean follow-up time of 9.2 months. All patients were re-evaluated by subjective questionnaire and clinical examination, and tested for anterior drawer at 20 degrees flexion using the KT-1000 Knee Ligament Arthrometer and the UCLA Instrumented Clinical Knee Testing Apparatus. Subjectively, four patients were rated as fair and one as good. The Lachman test was negative in two and trace or mildly positive in three patients. Pivot shift test was negative in all. Instrumented testing demonstrated three patients with increased anterior laxities outside the normal range, and two of these patients also showed reduced anterior stiffnesses which were beyond the normal range. Based on these results, the authors question the feasibility of arthroscopic repair of anterior cruciate ligament tears and suggest a more objective evaluation of this procedure.     

Revision anterior cruciate ligament reconstruction

Revision ACL surgery is indicated in patients who present with pathologic anterior laxity on clinical examination that reproduces their symptoms of instability during activities of daily living or athletic activities. The goals of the revision ACL surgery are to stabilize the knee, prevent further injury to the articular cartilage and menisci, and maximize the patient's function. Successful revision ACL surgery requires a thorough preoperative evaluation, including a detailed history, physical examination, and radiographic evaluation. Preoperative planning begins with a determination of the mechanisms of failure for the initial ACL reconstruction. Often a primary, as well as secondary cause, for failure can be identified. The determination of the cause of failure is the first step in a carefully-constructed treatment plan, which includes consideration of skin incisions to be used, method of graft removal, hardware removal, the need for a staged procedure or concomitant surgery, graft material selection, tunnel placement, graft fixation, and postoperative rehabilitation protocol. Despite the most meticulous planning, unanticipated findings may be encountered in the operating room, and the preoperative plan should have enough flexibility to accommodate these developments. Finally, it is crucial to counsel the patient preoperatively to limit his or her expectations regarding their surgical outcome. Given the complexity of revision ACL reconstruction, patient expectations must be adjusted to realistically match the potential for success. With proper planning, attention to detail, and appropriate patient expectations, revision ACL surgery can result in a beneficial and satisfying patient outcome.     

Imaging the anterior cruciate ligament

MR imaging has surpassed all other imaging modalities to become the "gold standard" for imaging evaluation of ACL injury. The accuracy and sensitivity of MR imaging for evaluation of ACL tears is excellent when correlated with clinical tests and arthroscopic findings, and is improved in equivocal cases with assessment of secondary signs for ACL tear. The MR imaging assessment of partial and chronic ACL tears is less accurate but is clinically useful. MR imaging provides information about associated injuries prior to surgery. Radiologic diagnostic methods for the assessment of ACL tears on MR images are well established; recent techniques such as dedicated cartilage imaging offer new information of use to clinicians about the sequelae of ACL injuries.     

Proprioception in anterior cruciate ligament deficient knees and its relevance in anterior cruciate ligament reconstruction

Injury to the anterior cruciate ligament (ACL) not only causes mechanical instability but also leads to a functional deficit in the form of diminished proprioception of the knee joint. “Functional” recovery is often incomplete even after “anatomic” arthroscopic ACL reconstruction, as some patients with a clinically satisfactory repair and good ligament tension continue to complain of a feeling of instability and giving way, although the knee does not sublux on clinical testing. Factors that may play a role could be proprioceptive elements, as the intact ACL has been shown to have significant receptors. Significant data have come to light demonstrating proprioceptive differences between normal and injured knees, and often between injured and reconstructed knees. ACL remnants have been shown to have proprioceptive fibers that could enhance functional recovery if they adhere to or grow into the reconstructed ligament. Conventionally the torn remnants are shaved off from the knee before graft insertion; modern surgical techniques, with remnant sparing methods have shown better outcomes and functional recovery, and this could be an avenue for future research and development. This article analyzes and reviews our understanding of the sensory element of ACL deficiency, with specific reference to proprioception as an important component of functional knee stability. The types of mechanoreceptors, their distribution and presence in ACL remnants is reviewed, and suggestions are made to minimize soft tissue shaving during ACL reconstruction to ensure a better functional outcome in the reconstructed knee.     

Replacement of the anterior cruciate ligament with a bone-ligament-bone anterior cruciate ligament allograft in dogs

Acute replacement of the canine anterior cruciate ligament (ACL) with a frozen, bone-ligament-bone anterior cruciate ligament preparation was studied using biochemical, immunologic, and biomechanical testing methods. Nine dogs were used for the study, six dogs received allografts and three received autografts. No tissue antigen matching was performed. All nine dogs were killed nine months after surgery. Necropsy examination revealed that the ACL was not present in three joints (one autograft, two allografts). The two autograft and four allograft ligaments available for mechanical testing sustained mean maximum loads that were 10% and 14%, respectively, of the mean maximum loads sustained by the contralateral ACL. Autoradiography indicated that cellular activity was more pronounced in the autograft specimens. Hydroxyproline uptake was 200% and 45% of normal in the autograft and allograft ligaments, respectively. Both autograft and allograft specimens were producing Type I collagen at the time of killing. Antidonor dog leukocyte antigen (DLA) antibody was detected in the synovial fluid taken at the time of killing from six of six dogs that received allografts and in zero of three dogs that received autografts.     

Rehabilitation of anterior cruciate ligament injuries

The previously outlined exercise program for the knee is for the instability that results from the loss of the anterior cruciate ligament and/or capsular ligaments laterally. Its success depends on communication between surgeon, therapist, and trainer. Each must understand what the other is doing and must follow the biomechanical and healing restraints of the surgery. The understanding of soft tissue healing is ongoing. Research in this field will greatly enhance the rehabilitation programs of the future.     

Rehabilitation after anterior cruciate ligament reconstruction

The "Frankfurt rehabilitation regimen" following anterior cruciate ligament reconstruction is presented. ACL rehabilitation is discussed in the light of knowledge on knee biomechanics and proprioception as well as clinical results of reconstruction. Special emphasis is given to exercise therapy.     

Anatomic double-bundle anterior cruciate ligament reconstruction

Objective: To retrospectively evaluate the early results of anatomic double-bundle anterior cruciate ligament (ACL) reconstruction and compare with the results of native ACL of the contralateral knee.M...     

Biomechanics and anterior cruciate ligament reconstruction

For years, bioengineers and orthopaedic surgeons have applied the principles of mechanics to gain valuable information about the complex function of the anterior cruciate ligament (ACL). The results of these investigations have provided scientific data for surgeons to improve methods of ACL reconstruction and postoperative rehabilitation. This review paper will present specific examples of how the field of biomechanics has impacted the evolution of ACL research. The anatomy and biomechanics of the ACL as well as the discovery of new tools in ACL-related biomechanical study are first introduced. Some important factors affecting the surgical outcome of ACL reconstruction, including graft selection, tunnel placement, initial graft tension, graft fixation, graft tunnel motion and healing, are then discussed. The scientific basis for the new surgical procedure, i.e., anatomic double bundle ACL reconstruction, designed to regain rotatory stability of the knee, is presented. To conclude, the future role of biomechanics in gaining valuable in-vivo data that can further advance the understanding of the ACL and ACL graft function in order to improve the patient outcome following ACL reconstruction is suggested.     

Guideline on anterior cruciate ligament injury

The Dutch Orthopaedic Association has a long tradition of development of practical clinical guidelines. Here we present the recommendations from the multidisciplinary clinical guideline working group for anterior cruciate ligament injury.The following 8 clinical questions were formulated by a steering group of the Dutch Orthopaedic Association.

• What is the role of physical examination and additional diagnostic tools?
• Which patient-related outcome measures should be used?
• What are the relevant parameters that influence the indication for an ACL reconstruction?
• Which findings or complaints are predictive of a bad result of an ACL injury treatment?
• What is the optimal timing for surgery for an ACL injury?
• What is the outcome of different conservative treatment modalities?
• Which kind of graft gives the best result in an ACL reconstruction?
• What is the optimal postoperative treatment concerning rehabilitation, resumption of sports, and physiotherapy?

These 8 questions were answered and recommendations were made, using the “Appraisal of Guidelines for Research and Evaluation” instrument. This instrument seeks to improve the quality and effectiveness of clinical practical guidelines by establishing a shared framework to develop, report, and assess. The steering group has also developed 7 internal indicators to aid in measuring and enhancing the quality of the treatment of patients with an ACL injury, for use in a hospital or practice.Anterior cruciate ligament injury is a common sports injury with a worldwide reconstruction rate of more than 200,000 per year (Meuffels et al. 2011). Clinically practical guidelines have been used for a long time; the Dutch Orthopaedic Association has a long experience of guideline development, since the 1980s. This is the recommendation from the multidisciplinary clinical guideline “anterior cruciate ligament injury”, set up and aimed at all the members of the medical disciplines concerned with diagnosis and treatment of anterior cruciate ligament injury. This injury is seen by a large number of diverse medical caregivers, and the importance of a team approach to injury treatment with a view to reintegration in sport has been established. This guideline was set up using the “Appraisal of Guidelines for Research and Evaluation (AGREE)” instrument (www.agreecollaboration.org).     

Imaging of the anterior cruciate ligament

The anterior cruciate ligament (ACL) is an important structure in maintaining the normal biomechanics of the knee and is the most commonly injured knee ligament. However, the oblique course of the ACL within the intercondylar fossa limits the visualization and assessment of the pathology of the ligament. This pictorial essay provides a comprehensive and illustrative review of the anatomy and biomechanics as well as updated information on different modalities of radiological investigation of ACL, particularly magnetic resonance imaging.     

Complications in anterior cruciate ligament surgery

There are many potential problems associated with ACL surgery; however, careful attention to detail can prevent problems from occurring or provide corrective options in the event they do occur. Multiple backup options are not only desirable but also essential to a successful outcome. By following these guidelines, ACL surgery can have good long-term results and return the recreational or higher-level athlete to sports participation.