Bridge-enhanced ACL Repair: Mid-term Results of the First-in-human Study

OBJECTIVES: Bridge-enhanced ACL repair (BEAR) is a new technique for treating midsubstance ACL injuries. The technique involves placing a scaffold loaded with the patient’s own blood between the torn ligament ends prior to using suture to realign the ends of the ligament (Fig. 1). Preclinical studies in large animal models found that the mechanical properties of the bridge-enhanced repaired ligaments were similar to reconstructed grafts, and that animals receiving the repair had less osteoarthritis compared to those receiving traditional ACL reconstruction. In this first-in-human study, our goal was to determine if bridge-enhanced ACL repair would be safe in humans and to compare the early outcomes of this new technique with ACL reconstruction in a small cohort of patients. METHODS: Nonrandomized controlled trial (Level 2). Both FDA Investigational Device Exemption Approval and IRB approval was obtained prior to starting the study. Twenty patients were enrolled in this study; ten undergoing the bridge-enhanced repair and ten patients having an ACL reconstruction with hamstring autograft. The inclusion criteria were patients ages of 18 to 35, surgery performed within 30 days for the BEAR technique and within 90 days for ACL reconstruction. All surgeries were performed by a single surgeon (LJM). RESULTS: At this time, we have six month follow-up data for 10 of the BEAR patients and 5 of the ACL reconstruction control patients. To date, no patients have had any infection or other serious adverse reaction to the implanted scaffold. At three months and six months post-operatively, there was no significant difference in IKDC scores for the two groups, and effusion and range of motion recovered similarly in both groups. The average side-to-side difference in AP laxity at three and six months post-operatively as measured by manual Lachman testing was also similar for the two groups. MRI showed presence of tissue in the region of the torn ACL in all ten BEAR patients at three and six months. CONCLUSION: Bridge-enhanced ACL repair can be performed in patients and early results show a low risk of adverse reactions to the implant. Early results suggest the knees are stable and recover motion after bridge-enhanced ACL repair. Whether these results will hold up in the longer term requires further study and we will plan to present additional data, good or bad, at the meeting in July.