Tension within a medial patellofemoral ligament graft increases with the lateral position of the tibial tuberosity, leading to better graft function and decreased patellar maltracking, according to published results.
Miho J. Tanaka, MD, and colleagues simulated flexion angles in knees with lateral patellar instability using 15 multibody dynamic models. The models were simulated in both a preoperative state and following medial patellofemoral ligament (MPFL) reconstruction, according to the study abstract.
“Maximum graft tension was significantly correlated with a parameter characterizing lateral position of the tibial tuberosity (maximum lateral tibial tuberosity to posterior cruciate ligament attachment distance, r 2=0.73, P<.001),” Tanaka and colleagues wrote in their abstract.
Tanaka and colleagues also found that low flexion angles allowed for optimal graft tension and decreased lateral patellar shift, as measured by the bisect offset index (0.81 after MPFL reconstruction, 0.71 in the preoperative condition).
“The results indicate that tension within an MPFL graft increases with the lateral position of the tibial tuberosity. The graft tension peaks at low flexion angles and decreases lateral patellar maltracking,” the researchers wrote in the abstract. “The factors that influence graft function following MPFL reconstruction need to be understood to limit patellar maltracking without overloading the graft or over constraining the patella.” – by Max R. Wursta
Disclosure: Tanaka reports she received grants from the Arthroscopy Association of North America during the conduct of the study; is an American Academy of Orthopaedic Surgeons committee member; and is on the American Journal of Sports Medicine electronic media editorial board, as well as the board of directors of the Patellofemoral Foundation.