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Registry: Anteromedial ACL drilling technique associated with revisions
Further study may help determine why revision rates are higher than with the traditional transtibial method.
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GENEVA — Results from the Danish Knee Ligament Reconstruction Registry indicate the introduction of the anteromedial technique for drilling femoral tunnels for ACL reconstruction was associated with a 4.7% revision rate at 3-year follow-up compared with a 2.6% revision rate for the traditional transtibial technique.
According to a presentation by
Rahr-Wagner and colleagues identified a 2.01 risk of revision for the AM femoral drilling technique compared with the TT technique. After adjusting for confounders, the risk of revision they calculated for the AM method increased to 2.04, according to the abstract.
Based on the Kaplan-Meier revision curve, the investigators calculated there was a 2% revision rate with the TT technique compared to a 4.7% revision rate in the AM model after 3 years of follow-up, Rahr-Wagner said.
The results are even more pronounced at 4 years, she said.
Preoperatively and postoperatively, Rahr-Wagner and colleagues recorded objective and subjective data and injury data, and on the day of surgery they recorded operative data, such as implant and graft choice, use of deep vein thrombosis prophylaxis and the presence of meniscus and cartilage tears.
The tunnel shown in this arthroscopic intercondylar view was drilled in the femur using the transtibial technique.
Image: Rahr-Wagner L
“Based on this national cohort study, a higher revision rate is seen in the AM group compared to the TT group,” Rahr-Wagner said. “A higher rate of positive pivot shift was seen in the AM group. These results are surprising and future studies need to look into causality of this.”
Rahr-Wagner noted she and colleagues analyzed gender, patient age less than 20 years, cartilage damage, prior knee surgery and meniscus treatment as additional relevant confounders, but they did not alter the results.
Lene Rahr-Wagner
“In this study, we are aware of the risk of unmeasured confounders, which we cannot adjust for,” Rahr-Wagner said. “We suggest a learning curve as one of the explanations of our results since the AM drilling technique has been introduced within the last 5 years as a necessity for the new trend for anatomical ACL reconstruction, and most Danish surgeons are trained in TT ACL reconstruction.”
Rahr-Wagner told Orthopaedics Today Europe this is her study’s key take-home message: “The introduction of the AM technique for femoral tunnel drilling for ACL reconstruction in Denmark has resulted in an increased risk of revision compared to the traditional TT technique. The risk of revision is generally low and a slight increase in technical failures due to introduction of a new and more complex technique may explain the present findings. Whether revision rates and clinical outcomes improve when the surgeons gain experience with AM portal techniques needs to be determined in future national registry-based studies. Further, the ongoing monitoring of the results with the AM approach is necessary and exemplifies the importance of a national registry.” – by Jeff Craven
Reference:
Rahr-Wagner L, Thillemann T, Mehnert F, et al. Increased risk of ACL revision after anteromedial compared to transtibial technique for femoral drill hole placement during ACL reconstruction. Result from the Danish registry of knee ligament reconstruction. Paper #AW10-516. Presented at the European Society of Sports Traumatology, Knee Surgery and Arthroscopy Congress 2012. May 2-5. Geneva.
For more information:
Lene Rahr-Wagner, MD, can be reached at the Department of Orthopaedic Surgery at Aarhus University Hospital, Olof Palmes Allé 43-45, DK-8200 Aarhus, Denmark; email: lrw@dce.au.dk.
Disclosure: Rahr-Wagner has no relevant financial disclosures.