HSS Tackles Best Approach for ACL-Deficient Knees

When it comes to anterior cruciate ligament (ACL)-deficient knees, orthopedic surgeons are revisiting an old friend. A new laboratory study from Hospital for Special Surgery (HSS) in New York set out to compare the effect of lateral closing-wedge (LCW) and medial opening-wedge (MOW) high tibial osteotomy (HTO) on tibiofemoral and patellofemoral alignment in the ACL-deficient knee. Researchers, led by Anil Ranawat, M.D., performed anterior drawer, Lachman, and pivot-shift tests on 16 cadavers, and measured anterior tibial translation and tibial rotation for the native and ACL-sectioned knee.

Dr. Ranawat, sports medicine surgeon at HSS, told OTW, “There is a renewed interest in the role of high tibial osteotomy within orthopaedic surgery. Recently, neutralization of posterior tibial slope has been associated with decreased anterior tibial translation. Thus, HTO can be considered an effective treatment for the ACL-deficient knee. Prior studies looking at the impact of HTO in the ACL-deficient knee have suggested that HTO can produce knee stability, however the ideal osteotomy type has yet to be determined. As such, we wanted to directly compare medial opening wedge versus lateral closing wedge for providing stability to the ACL-deficient knee. Additionally, we felt that osteotomy type may influence coronal and sagittal plane tibiofemoral alignment, while also affecting tibial rotation and patellar mechanics. As such, we wanted to formally investigate these parameters. Finally, because the importance of posterior tibial slope in ACL-deficiency is increasingly well recognized, we wanted to investigate how osteotomies about the knee influence posterior tibial slope.”

“Prior to our study, the comparative impact of medial opening wedge versus lateral closing wedge on sagittal knee alignment (i.e., tibial slope) has not been studied. Posterior tibial slope neutralization has been recommended for revision ACL procedures and the impetus to perform these procedures to manipulate posterior tibial slope has increased. However, we do not know how different osteotomies about the knee impact posterior tibial slope. In addition, the relationship between tibial and patellofemoral alignment and kinematics had not been well studied when comparing the two osteotomies types.”

“Both medial opening and lateral closing wedge osteotomies are effective at correcting coronal plane deformities, however when looking to also neutralize posterior tibial slope, a lateral closing wedge osteotomy may be the most reliable osteotomy type. However, it should be noted that the slope neutralization benefits of lateral closing wedge osteotomies comes at the price of altered patellofemoral mechanics more so than medial opening wedge osteotomies. The clinical impact of these altered patellofemoral mechanics still remains unclear.”

“The study findings were in line with our prior hypotheses and are not very surprising to study investigators. We knew from historic data that closing wedge tibial osteotomy was an effective treatment for the ACL-deficient knee. This study corroborated it.”