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Surgeons debate merits of transtibial vs anteromedial portal drilling in ACL surgery
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In a debate at Orthopedics Today Hawaii 2012, Nicholas A. Sgaglione, MD, argued that anteromedial portal drilling leads to a more anatomic ACL reconstruction than transtibial tunneling. But, Jack M. Bert, MD, countered that shorter tunnels often seen with the anteromedial technique may compromise graft incorporation and lead to posterior wall blowout.
Less laxity, tunnel expansion
“The literature [has] shown that the low accessory anteromedial portal is the way to go,” Sgaglione said. “[We] want more anatomic femoral footprints.”
He cited an MRI study by Abebe and colleagues which showed that the independent tibial-tunnel technique was more anatomic than transtibial (TT) drilling. Research by Steiner and colleagues highlighted the superior biomechanics of using the anteromedial portal (AMP), and found less AP and rotational laxity with the technique compared to the transtibial approach.
“By trying to get to the femoral footprint through your TT tunnel, you are doing two things […],” Sgaglione said. “You are posteriorizing your tibial tunnel to get to that position. But secondly, you are changing the obliquity of your tunnel aperture. You have tibial tunnel expansion that is much less significant than with independent accessory portal drilling.”
Nicholas A. Sgaglione
Tips for the AM portal
Sgaglione warned that surgeons should use caution when using the AM portal in cases of shorter tunnels in smaller knees. In these cases, he advised surgeons to drill at about 110° in flexion. Hyperflexion and limited vision can be an issue. It is therefore necessary to do a “definitive fat pad excision” and use a pump, Sgaglione said.
To avoid cartilage and medial meniscal injuries, he suggested the use of a monofluted reamer to get into the femoral footprint. For posterior cortical breakdown, “mark the pilot hole,” view it twice and come in with knee flexion, Sgaglione said. When navigating the “killer turn” coming in lower anatomically, “use a probe as a pulley and an small Freer elevator to guide the tone block in,” he recommended.
“My opinion about this is, go for the most anatomic approach,” Sgaglione said. “Use independent drilling of the femoral tunnel.”
Complications with AM portals
Bert argued that the transtibial method can produce an anatomic reconstruction. He highlighted a study by Piasecki and colleagues which found that insertional overlap on the tibia was 98% and 88% on the femur using the technique.
Jack M. Bert
Bert, who is Section Editor of Orthopedics Today’s Business of Orthopedics, cautioned that complications using the AM portal include smaller tunnels and risk of posterior wall blowout. He cited a cadaver study by Miller and colleagues which found that the AM portal created an ellipse shape with a volume shorter and smaller than the tunnels made using the transtibial technique. The researchers also found an increased risk of blowout in 19% of cadavers treated using the AM portal. A study by Bedi and colleagues also found that the approach resulted in greater femoral tunnel obliquity, shorter tunnels and posterior wall blowout.
Correct positioning
Bert recommended “more distalization of the external tibial starting point as opposed to changing the tibial guide angle, which is what most [orthopedists] want to do.” He also suggested that surgeons avoid tunnel lengths less than 15 mm “because there is greater pullout.”
“AMP is a slight improvement in anatomic position in the ACL graft,” Bert said. “There is no question about that. There is no evidence that if the graft is placed in the 9:30/10:00 position, the clinical result, including the instability exam, is worse using the TT approach. Make certain when doing the TT approach, that a vertical graft is avoided and that a PCL impingement does not occur. In vitro, there appears to be a higher incidence of shorter tunnels, which can compromise graft incorporation and posterior wall blowout with the AMP approach.” – by Renee Blisard
References:
- Bert JM. So how and where do I really place my tunnels?
- Sgaglione N. Why you should use an accessory AM portal.
- Both presented at the Orthopedics Today Hawaii 2012. Jan. 15-18. Wailea, Hawaii.
- Abebe ES, Moorman CT III, Dziedzic TS, et al. Femoral tunnel placement during anterior cruciate ligament reconstruction: An in vivo imaging analysis comparing transtibial and 2-incision tibial tunnel–independent techniques. Am J Sports Med. 2009; 37:1904-1911.
- Bedi A, Raphael B, Maderazo A, et al. Transtibial versus anteromedial portal drilling for anterior cruciate ligament reconstruction: A cadaveric study of femoral tunnel length and obliquity. Arthroscopy. 2010; 26:342-350.
- Piasecki DP, Bach BR, Alejandro AA, et al. Anterior cruciate ligament reconstruction: Can anatomic femoral placement be achieved with a transtibial technique? Am J Sports Med. 2011; 39:1306-1315.
- Steiner ME, Battaglia TC, Heming JF, et al. Independent drilling outperforms conventional transtibial drilling in anterior cruciate ligament reconstruction. Am J Sports Med. 2009; 37:1912-1919.
For more information:
- Jack M. Bert, MD, can be reached at the University of Minnesota School of Medicine in Minneapolis, 420 Delaware St. SE # 806, Minneapolis, MN 55455; 612-347-2663; email: bertx001@gmail.com.
- Nicholas A. Sgaglione, MD, can be reached at the University Orthopaedic Associates and the Department of Orthopedic Surgery, North Shore Long Island Jewish Medical Center, 611 Northern Blvd., Great Neck, NY 11021; 516-723-2663; email: nas@optonline.net.
- Disclosures: Bert is a consultant for Smith & Nephew, Exactech, Wright Medical Technology, Tornier, Genzyme and Exscribe, is on the board of trustees of the Arthroscopy Journal. Sgaglione receives royalties from Biomet Sports Medicine and is president-elect of the Arthroscopy Association of North America.