Advances in Performance Medicine

The anterior cruciate ligament (ACL) is one of four major ligaments connecting the tibia to the femur.

Rupture of ACL is common, especially amongst active people and those participating in sports. Approximately 1 in 3,000 Americans tear their ACL annually (Davarinos et al.)

Body’s healing response is so poor due to limited blood supply to the ligament.

Without surgery the ACL deficient knee limits patients ability to perform, specifically movement in lateral plane. Continued performance

on torn ACL often leads to damage to medial meniscus and other ligaments.

Most isolated ACL tears are non-contact. Depending on severity meniscus/MCL are more commonly

involved here.

Usually a result of hyperextension or abnormal rotation, cause by rapid deceleration following or leading into a jump or cut. (Petterborg et. al) Rapid deceleration w/ hyperextension ex: Soccer player Rapid deceleration w/external tibia to internal femur rotation

ex: Running back cutting left, basketball player landing poorly.

Contact ACL tears – forced hyperextension Most common instance results after contact from medial

(inside) or lateral (outside) side w/ foot planted and involve multi-ligament tear.

Forced Hyperextension: Hits from anterior side w/ planted foot + near-full or full extension result in knee dislocation + multi-ligament/meniscus tears.

~3000 B.C. – Cruciate ligaments first described in Smith Papyrus

~150 A.D. – Roman Physician Claudius Galen recognized that cruciate ligaments were a structure supporting joints of knee, not an element of the nervous system as previously believed.

1903 – Medical reports of ACL repaired using catgut sutures to reattach torn ends of ligament. Reported as a success. (Davarinos et al.)

1934 – Riccardo Galeazzi first to describe ACL reconstruction using graft of hamstring tendon, 18 month recovery.

1985 – Arthroscopic ACL Reconstruction – less invasive, small incision in knee, use of fiber optics and small instruments (Warren et al.)

1990s to Present – Patella tendon/hamstring graft method.

Torn ends of ligament are removed

Holes drilled where ligament ends existed.

1/3 of patella tendon is shaved off along with small sections of bone.

Patella tendon is threaded through holes drilled in tibia and femur and screwed in. The bone sections on the patella are healed together with the tibia and femur bones.

Same process with hamstring

Drawbacks of this surgery include

80% occurrence of osteoarthritis 15 years removed from surgery (Boston Children’s Hospital)

Risk of fracturing/over-shaving tendons

Post-surgery rehab includes rehab of patella tendon/hamstring

It is questionable whether or not hamstring ever regains full strength

BEARTM surgery involves the placement of a sponge, created with specialized proteins, in between the torn ends of the ligament. (Boston Children’s Hospital)

The torn ends are sutured to the sponge, which has been injected with blood.

The blood acts as a stimulus for healing of the ligament.

Healing ACL tissue grows into the sponge and replaces it.

Initial testing was done on pig’s knees. 64 pigs were used and at the 3, 6, and twelve month marks, similar strength seen in ACL with less evidence of osteoarthritis/cartilage damage (Murray PhD et al.)

Results of a 10 patient safety trial approved in 2014 saw all 10 patients develop full and healthy ACLs at the 10 month mark, full activity after 1 year.

Less scar formation

No risk of damaging patella tendon or hamstring

Tendons preserved, no rehab necessary for patella/hamstring

Less pain due to absence of osteoarthritis or tendinitis post surgery.

Highly experimental, long-term risks unknown as 10 patient study is only a year and a half removed

Not yet approved so not yet publicly available

Gold standard procedure is proven

Rehabilitation length in 10 patient study was same as with gold standard.

Following the success of the 10 patient safety trial, a 100 person clinical trial was approved for phase 2 of trials. (The Boston Globe)

In this trial 2/3 of patients will receive BEAR surgery while 1/3 will receive grafting reconstruction.

If BEARTM is found to be more successful, it will likely be accepted within 4 to 5 years. (Murray et al.)

Davarinos, Nikolaos, Barry James O'Neill, and William Curtin. "A Brief History of Anterior Cruciate Ligament Reconstruction." A Brief History of Anterior Cruciate Ligament Reconstruction. Hindawi Publishing Corporation, 17 Apr. 2014. Web. 25 Oct. 2016.

Warren, Russell F., and Teresa Lamb. "Anterior Cruciate Ligament (ACL) Injuries – Then and Now." Hospital for Special Surgery. Hospital for Special Surgery, 16 Mar. 2012. Web. 25 Oct. 2016.

Petterborg, Larry J., Jennifer Beasley, and Alison Gooch. "Anterior Cruciate Ligament." : Mechanism of Injury. University of Missouri-Columbia, n.d. Web. 25 Oct. 2016.

Murray, Martha, PhD. "Use of a Bioactive Scaffold to Stimulate Anterior Cruciate Ligament Healing Also Minimizes Posttraumatic Osteoarthritis after Surgery." National Center for Biotechnology Information. U.S. National Library of Medicine, 15 July 2013. Web. 25 Oct. 2016.

Boston Children's Hospital. "Bridge-Enhanced (TM) ACL Repair Clinical Trial Overview." ACL Program. Boston Children's Hospital, 2013. Web. 30 Oct. 2016. Picture also from Boston Children’s Hospital

Springer, Shira. "The Future of Treating ACL Tears: Less Invasive Surgery." The Boston Globe. The Boston Globe, 8 Nov. 2014. Web. 25 Oct. 2016

Greenhouse, Pat. "Children's Hospital Develops New Surgery That Could Revolutionize Knee Repairs - The Boston Globe." BostonGlobe.com. The Boston Globe, 23 Mar. 2016. Web. 25 Oct. 2016.

Webmd.com. Web MD, n.d. Web. 25 Oct. 2016.