Arthrometric Aspects of Anterior Cruciate Ligament Surgery Before and After Reconstruction With Patellar Tendon Grafts

Abstract

Summary: Instrumented arthrometry is an important treatment adjunct for anterior cruciate ligament (ACL)-deficient patients before and after patellar tendon reconstruction, which provides objectivity to other subjective outcome measures and allows for accurate comparison between studies. Increasing numbers of clinical reports are using arthrometry to objectively report anterior displacements. Arthrometry measurements allow the worldwide orthopaedic community to accurately compare and evaluate reported subjective results. It should be noted that patient satisfaction and subjective evaluations by the examiner and patient may overestimate the presumed ligamentous stability, and in these cases, the KT arthrometer provides important objectivity. This objective data may be the only means of early detection of laxity after ACL reconstruction. In this article, a review of the available data regarding arthrometry before and after patellar tendon ACL reconstruction is presented as well as a rationale for selecting a maximum manual side-to-side difference of 3 mm or an absolute laxity of 10 mm as the diagnostic criteria for ACL deficiency. Knee laxity testing data should be incorporated into the objective preoperative and postoperative evaluation of the ACL-deficient patient, and the goal of reconstruction should be to match the contralateral normal knee. Arthrometry data are important to the researcher for objective evaluation and comparison of populations and to clinicians for objective outcomes in individual patients after patellar tendon ACL reconstruction. Key Words: Arthrometry—KT—Laxity—Patellar tendon graft—ACL reconstruction—Outcomes. During the last 4 decades, advances in the understanding and treatment of knee instability have progressed at a rapid rate. Refinements in physical examination techniques, improved radiographic modalities, advances in the principles of ligament healing and rehabilitation, improved surgical techniques, and the constant integration of new technology as it becomes validated have contributed to an improved ability to care for the patient with an anterior cruciate ligament (ACL)-deficient knee. During the 1980s, several ligament testing devices were developed in an attempt to quantitate anteroposterior (AP) displacement of the knee joint. The Lachman, pivot shift, and anterior drawer physical examination tests often vary from examiner to examiner, making comparison difficult. Objective, quantitative ligament testing devices provide the opportunity to compare populations of patients more accurately, and allow for objective evaluation of individual patients before and after ACL reconstruction. Clinical studies that evaluate the results of ACL reconstruction should use objective quantifiable instrumented ligament testing in addition to the subjective clinical grading reported by various authors. This is especially true when evaluating new technology or methods. The KT-2000 and its predecessor, the KT-1000 arthrometer, have most often been reported in the literature and will provide the basis for most of this article.