aaosnow.org February 2013 AAOS Now

“We believe this occurred sec-ondary to the difference in the bony anatomy between the me-dial and lateral compartments of the knee,” they write. “The two convex opposing surfaces of the femur and tibia in the lateral com-partment have an inherent bony instability, which is likely a major contributing factor for the lack of soft-tissue healing with posterolat-eral knee injuries in both the rab-bit and canine models and human clinical experience.”

They also confirmed that insta-bility due to an injured PLC led to early onset arthritis in the medial compartment.

The studies led to a number of important clinical advancements in the treatment of complex knee injuries. For example, patients who need either a ACL or PCL reconstruction should be carefully assessed for posterolateral knee injuries, because not treating the posterolateral injury concurrent with the reconstruction increases the risk for failure.

From their anatomic and biome-chanical studies, the researchers developed anatomic techniques for reconstructing the FCL, pop-liteus tendon, and popliteofibular ligament using an Achilles tendon allograft, divided into two limbs with two separate bone plugs (Fig. 1). Biomechanical testing showed that the technique restored

static stability to the knee for all applied loads.

Finally, they noted that in some PCL tears, the FCL remains intact, but the popliteus tendon needs to be reconstructed. The anatomic reconstruction they developed uses a semitendinosus autograft and restores stability to knees with this injury.

In summarizing the clinical les-sons of their work, Dr. LaPrade and his coauthors wrote that “proper treatment of grade 3 PLC injuries requires a comprehensive understanding of the anatomy and clinically relevant biomechanics to synthesize the various clinical exams utilized to diagnose these injuries.” Stress radiographs, MRI scans, and arthroscopy may also be indicated.

In patients with chronic postero-lateral knee instability and varus alignment, the varus alignment should be corrected before soft tis-sue reconstruction to prevent graft failure. For acute injuries, out-comes are best when intervention is performed in the first few weeks following injury; a combined hy-brid repair of the biceps or lateral capsule, along with anatomic re-constructions of the FCL and/or popliteus tendon, provides excel-lent patient clinical and objective outcomes. For chronic PLC inju-ries, an anatomic PLC reconstruc-tion restores objective stability to

the knee and significantly improves patient outcomes.

For links to additional information, see the online version of this article at www.aaosnow.org

Dr. LaPrade’s coauthors include Steinar Johansen, MD; Lars Engebretsen, MD, PhD; Chad J. Griffith, MD; Benjamin R. Coobs, MD; and Andrew G. Geeslin, MD.

Disclosure information: Dr. LaPrade—Arthrex; Knee Surgery;

Sports Traumatology; Arthroscopy; American Journal of Sports Medicine; Dr. Engebretsen—DePuy, Arthrex, Nycomed, Smith & Nephew, British Journal of Sports Medicine, Acta Orthopaedica, Knee; Knee Surgery, Sports Traumatology, Arthroscopy, Journal of Bone and Joint Surgery–American. The other authors report no conflicts.

Terry Stanton is senior science writer at AAOS Now. He can be reached at tstanton@aaos.org

47Research and Quality

fold (ie, bridge across the wound site) inhibits ACL healing.

2. Placement of a substitute provi-sional scaffold can restore func-tional healing.

3. Growth factor delivery systems can be specifically designed for use in the joint.

If these findings hold up in clini-cal trials, a less-invasive method for treating patients with ACL tears would be available. This new technique could also decrease the risk of premature OA after ACL injury, but verifying this will take much longer.

Dr. Murray’s proposal to com-plete the needed preclinical studies of safety and efficacy in prepara-tion for clinical trials has been accepted into the FDA’s Early Feasibility Pilot program. Trials will begin once these studies are completed and the approved docu-mentation is in place.

Because most of the 400,000 pa-tients with ACL tears in the United

States are young and otherwise healthy and active, “there is a need for improved treatment of these in-juries,” said Dr. Murray. “We hope to begin to shift some of the focus for research in this area from resec-

tion and replacement to repair and regeneration of ACL injuries.”

Disclosure information: Dr. Murray—National Institutes of Health (NIH); Dr. Fleming: NIH; American Journal

of Sports Medicine; Journal of Applied Biomechanics.

Terry Stanton is senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Fig. 1 Schema of bio-enhanced ACL repair. (A) Defect model. (B) Femoral and tibial tunnels (dashed lines) and EndoButton pulled through femoral tunnel and placed on femoral cortex. The EndoButton is loaded with 3 sutures, resulting in 6 free-ending strands (4 red and 2 green). (C) A Kessler suture is placed in the tibial ACL stump, and a collagen scaffold is threaded onto 4 strands (red), pushed into the notch, and saturated with 3 mL of platelet-rich plasma. (D) The 4 suture strands running through the scaffold (red) are passed through the tibial tunnel, while the remaining suture (green) is tied to the tibial Kessler suture, using it as a pulley to reduce and stabilize the tibial ACL stump. (E) The transtibial sutures (red) are tightened and tied over an extracortical button. The free ends of the ACL suture pulley (green) are knotted to secure the reduced ACL in the collagen-platelet composite.REPRODUCED WITh PERMISSIOn FROM VAVkEn P, FLEMInG BC, MASTRAnGELO An, MAChAn JT, MURRAy MM: BIOMEChAnICAL OUTCOMES AFTER BIO-EnhAnCED AnTERIOR CRUCIATE LIGAMEnT REPAIR AnD AnTERIOR CRUCIATE LIGAMEnT RECOnSTRUCTIOn ARE EqUAL In A PORCInE MODEL. Arthroscopy 2012;28(5):672-680.

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Next month in AAOS Now

• Chicago Welcomes AAOS

• New Public Service Campaign

• Women in Orthopaedics

• Obesity and Osteoarthritis

AAOS Now_2013 February.indd 47 1/23/2013 2:39:16 PM