Document Title: Jarvinen-AJSM-Sep04.shtml
Article Title: Bone Density and Insertion Torque as Predictors of Anterior Cruciate Ligament Graft Fixation Strength
Authors: Teppo L. N. Järvinen, MD, PhD*, Janne T. Nurmi, DVM, PhD, and Harri Sievänen, ScD
Publication: American Journal of Sports Medicine, Baltimore, Maryland
Date: September 2004
Volume 32, pages 1421-1429
Keywords: soft-tissue ACL grafting, autografting, graft anchorage, fixation

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Comments: Jarvinen et al. found that the anchorage (fixation) strength of a soft-tissue ACL autograft cannot be foretold by the person's native local bone-mineral density, nor by the torque exerted on the interference screws during the installation process. (This is a cadaver-type study.)

ABSTRACT

Background: Bone mineral density and interference screw insertion torque are thought to be useful predictors of anterior cruciate ligament graft fixation strength.

Hypothesis: Bone mineral density and insertion torque are reliable predictors of anterior cruciate ligament graft fixation strength.

Study Design: Randomized experimental study.

Methods: The volumetric bone mineral density, maximum insertion torque, and initial fixation strength (determined both as cyclic-loading-induced displacement and yield load) were recorded on 21 pairs of anterior cruciate ligament reconstructions. To assess the accuracy of bone mineral density and insertion torque in predicting the fixation strength, half of the specimens were first used to determine the regression equations between the variables, and then the data from the remaining specimens were used to validate the prediction equations.

Results: Despite the relatively high group correlations, the ability of bone mineral density and insertion torque to predict the strength of graft fixation was poor. Errors ranging from –150% to 92%, –22% to 50%, –56% to 121%, and –23% to 50% were observed when bone mineral density and insertion torque were used to predict individual cyclic-loading-induced displacement and yield load, respectively.

Conclusions: Neither bone mineral density nor insertion torque provides a sufficiently accurate prediction of the fixation strength of an individual soft tissue anterior cruciate ligament graft.

Clinical Relevance: Bone mineral density and insertion torque cannot be used to estimate the strength of interference screw fixation in anterior cruciate ligament reconstruction.

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