2015 ISAKOS Biennial Congress ePoster #1107

The Biomechanical Effect of Simulated Trochlear Dysplasia in Cadaver Knees

Annemieke Van Haver, PhD, MSc, Antwerp BELGIUM
Karel De Roo, BSc BELGIUM
Luc Labey, Leuven BELGIUM
Tom Claessens, PhD, Ghent BELGIUM
Peter Verdonk, MD, PhD, Zwijnaarde BELGIUM
Ghent University / Monica Orthopaedic Research Institute, Ghent / Antwerp, BELGIUM

FDA Status Not Applicable

Summary: Trochlear dysplasia (TD) was simulated in 4 cadaver knees by implanting 3D printed TD implants. Experimental testing demonstrated that TD significantly affects patellofemoral biomechanics and that the trochlear bump is a key provocative factor for severely deviating patellofemoral biomechanics.

Abstract:

Trochlear dysplasia (TD) is presented in many variations which can be classified as Dejour type A, B, C and D. How these variations affect the patellofemoral biomechanics is unknown and difficult to investigate in a patient population given the multifactorial character of the condition. The objective of this study was to simulate different types of TD in cadaver knees to investigate how these types affect the patellofemoral biomechanics
TD was simulated in 4 cadaveric knees using cadaver-specific trochlear implants and cutting guides. For each knee, 5 trochlear implants were manufactured; 4 different trochlear dysplastic implants and 1 implant which replicated the native cadaver trochlea. The implants were printed with a multi-material 3D printer.
This permitted printing the cartilage layer in a softer material, allowing for articular shape adaptation. The 3D models of the modified cadavers were graded with the Dejour classification. Patellofemoral biomechanics was evaluated during a squat simulation, open chain extension simulation and a patellar stability test.
TD affected the patellofemoral kinematics, contact area, contact pressure and stability significantly.
The four Dejour types did not demonstrate four different patterns in patellofemoral biomechanics. However, within the trochlear dysplastic group, the implants graded as Dejour type D showed the largest deviations for the kinematical parameters and the implants graded as Dejour type B and D showed the largest deviations for the patellofemoral contact areas and pressures.
Investigating the relation between the trochlear shape and patellofemoral biomechanics improved our understanding of short-term (maltracking, increased pressure and instability) as well as long-term (osteoarthritis) effects of different types of trochlear dysplasia. The trochlear bump is a key provocative factor for severely deviating patellofemoral biomechanics, explaining a higher incidence of osteoarthritis and a better outcome of trochleoplasty in Dejour type B and D, both characterised by a trochlear bump.