Double bundle acl repair system

Abstract

A system for single tunnel, double bundle anterior cruciate ligament reconstruction includes implant constructs and instruments. The implant constructs provide a combination of cortical fixation and bone tunnel aperture fixation. The implant constructs separate a graft into distinct bundles. The instruments are used to prepare shaped bone tunnels to receive the implant constructs and graft bundles. Methods for reconstructing the antero-medial and postero-lateral bundles of the anterior cruciate ligament may rely on single femoral and tibial tunnels and a single strand of graft.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of:[0002]U.S. application Ser. No. 13 / 221,723, filed Aug. 30, 2011, entitled DOUBLE BUNDLE ACL REPAIR, Attorney's docket no. MYE-1 CIP1, which is pending.[0003]U.S. patent application Ser. No. 13 / 221,723 is a continuation-in-part of:[0004]U.S. application Ser. No. 12 / 751,072, filed Mar. 31, 2010, entitled DOUBLE BUNDLE ACL REPAIR, Attorney's docket no. MYE-1, which is pending.[0005]U.S. application Ser. No. 12 / 751,072 claims the benefit of:[0006]U.S. Application No. 61 / 164,980, filed Mar. 31, 2009, entitled DOUBLE BUNDLE ACL REPAIR, Attorney's docket no. MYE-1 PROV, which is expired.[0007]U.S. patent application Ser. No. 13 / 221,723 also claims the benefit of:[0008]U.S. Application No. 61 / 378,754, filed Aug. 31, 2010, entitled DOUBLE BUNDLE METHOD WITH MODULAR POROUS DOUBLE BUNDLE ACL IMPLANT AND ASSOCIATED INSTRUMENTS, Attorney's docket no. MYE-2 PROV, which is expired; and[0009]U.S. Application No. 61 / 4...

AI Technical Summary

Benefits of technology

The present patent provides a new system and method for repairing damaged knee ligaments using a single tunnel and double bundle graft. The system uses a combination of cortical and aperture fixation to secure the graft to bone. The graft bundles are anatomically oriented to restore natural knee motion. The system also includes a single tunnel in both the femur and the tibia, which may be shaped differently to match the natural path of the ACL. The system can deliver therapeutic agents to the graft implantation site. Overall, this new system simplifies the surgery, reduces complications, and restores more natural knee dynamics.

Problems solved by technology

Initial attempts at repair of this ligament resulted in nearly uniform failure of the ligament to stabilize the knee joint.

Tibial and femoral bone tunnel placement has been a very controversial topic.

Anterior placement of the femoral tunnel has become generally accepted as a technical cause of graft failure.

However, among surgeons who prefer soft tissue grafts, a wide variety of fixation devices are used with little consensus as to what is best.

There may be biomechanical evidence that aperture fixation may lead to increased graft stiffness.

The use of an interference screw alone may cause tunnel widening and may prevent circumferential tendon-tunnel healing, which may result in inferior strength and stiffness at 4 weeks compared with cortical fixation.

The high stiffness provided by distal cortical fixation may reduce the graft tension required to restore stability and may lower graft tension during open-chain exercise.

Although cross-pin fixation on the tibial side may be popular among surgeons, there is a paucity of clinical data pertaining to it, and the clinical series that have been published to date have shown mixed results.

Despite advancements in single bundle ACL reconstruction, a review of the literature demonstrates that between 10% and 30% of patients report persistent instability following single bundle ACL reconstruction surgery.

These studies suggest that conventional single bundle ACL reconstruction may successfully restore anteroposterior knee stability, but the reconstructed knee may be unable to resist combined rotatory loads.

The most common cause of failure of any kind of ACL reconstruction is improper bone tunnel position.

The double bundle procedure, which is more complex than the single bundle technique, may be expected to have more misplaced tunnels.

For example, dual tunnels can interfere with each other when they are not meticulously positioned.

In particular, a poorly positioned PL tunnel may displace a subsequently formed AM tunnel too far anteriorly, resulting in roof impingement and potential graft rupture.

The greater complexity of double bundle repair results in longer surgical time.

Suitable femoral fixation options may be limited.

Cross-pin femoral fixation may not be feasible for double bundle ACL reconstruction due to anatomical constraints in the vicinity of the femoral tunnel apertures.

This may result in PCL impingement as well as notch impingement simply due to the size of the grafts.

Vertical placement of the ACL graft at the apex of the femoral notch may cause the graft to wrap around the PCL, which may cause high tension in the graft when the knee is flexed.

High graft tension in flexion may cause the graft to stretch out or may prevent the patient from regaining full knee flexion.

Notch or PCL impingement, loss of knee flexion and eventual stretching and failure of the tissue may result.

Revision is also more difficult with double bundle ACL reconstruction than with single bundle ACL reconstruction.

It may be problematic to place revision tunnels anatomically if there is no bone into which to drill.

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