Treatment of Acute Proximal Anterior Cruciate Ligament Tears—Part 2: The Role of Internal Bracing on Gap Formation and Stabilization of Repair Techniques

Abstract

Background: The latest biomechanical studies on some form of internal bracing have shown improved stabilization for anterior cruciate ligament (ACL) repair, but gap formation and load-sharing function have not yet been reported. Hypothesis: Internal bracing of an adjustable ACL repair construct provides improved stabilization with reduced gap formation and higher residual loading on the ACL. Study Design: Controlled laboratory study. Methods: Internally braced ACL repair constructs with single– and double–cinch loop (CL) cortical buttons, a knotless suture anchor, and a single-CL cortical button with adjustable loop fixation (CLS-ALD) were tested (n = 20 each) in a porcine model at 4 different loads (n = 5 each) over 4000 cycles at 0.75 Hz (n = 80 total). The CLS-ALD technique allowed for additional preconditioning (10 cycles at 0.5 Hz). Test results of the isolated internal brace groups served as a baseline for comparison. Lastly, specimens were pulled to failure (50 mm/min) with a cut internal brace. Final loading and gap formation on the ACL repair construct as well as ultimate strength were analyzed. Results: A statistical significance for peak loads over peak elongation was found between the CLS-ALD and all other reinforced groups (analysis of covariance, P < .001). Accordingly, the adjustable repair technique showed improved load-bearing capability with the internal brace compared with all other fixed repair groups and revealed significantly higher loads than the knotted single-CL group. Also, significantly reduced gap formation was found for the CLS-ALD compared with all other groups ( P < .001), with no gap formation up to 150 N with a final gap of 0.85 ± 0.31 mm at 350 N. A significantly higher ultimate failure load (866.2 ± 104.0 N; P < .001) was found for the button-fixed internal brace group compared with all other groups. Conclusion: Internal bracing had a crucial role in improving the stabilization potential of ACL repair at loads occurring during normal daily activity. The added strength of the internal brace allowed for reducing peak loads on the ACL repair construct as well as restricting gap formation to below 3 mm at loads up to 350 N. Clinical Relevance: Improvements in the mechanical characteristics of current ACL repair techniques that enable reduced gap formation and allow for early range of motion and accelerated rehabilitation may strengthen the self-healing response with the formation of stable scar tissue.

Good to Excellent Functional Short-Term Outcome and Low Revision Rates Following Primary Anterior Cruciate Ligament Repair Using Suture Augmentation

“…Thus, it remains unclear whether these results can be reproduced for injuries due to non-winter sports injuries. (2) The mean age of the patients treated in our study is high, also in comparison to other studies on ACL repair using SA [ 12 , 13 , 40 ]. This is possibly due to the higher patient age in the ski region where this study was conducted.…”

Knotless Primary Anterior Cruciate Ligament Repair with Adjustable Loop Device and Internal Brace Augmentation

“… 26 The use of an ALD for primary ACL repair was tested in an experimental model compared to use of either a single cinch or double cinch suture, or the use of a suture anchor. 15 This recent study found the ALD with retensioning was superior to the other three techniques and led to significantly improved stabilization and reduced gap formation, along with the highest ultimate strength compared with the other tested techniques.…”

“…Correlating with these two published clinical papers on use of the IB was a recent biomechanical study which showed the benefit of adding an IB to either a single or double cinch type suture configuration for a primary repair relative to decreasing overall displacement and gap formation. 15 …”

“… 1 A promising technique not previously clinically described is a knotless technique that employs adjustable loop fixation, which was recently shown in a biomechanical study to be superior to both suture tying and anchor fixation for primary repair. 15 This is the focus of this technique paper for primary ACL repair, along with IB augmentation.…”

The healing potential of an acutely repaired ACL: a sequential MRI study

“…In the present series there was no augmentation with suture nor scaffold due to the desire to optimize the favorable healing environment. However, some authors have suggested the use of an internal brace (IB) at the time of ACL repair to protect the biological environment and prevent displacement of the tissue in the healing phase by controlling anterior translation [ 13 , 21 , 25 , 26 ]. Other authors, in cases of delayed surgery, have promoted the use of biological scaffold or stimulation, especially when a shorter retracted stump is found, to optimize the healing environment between the torn ends of the ligament [ 27 ].…”