Groove‐deepening trochleoplasty reduces lateral patellar maltracking and increases patellofemoral contact pressures: Dynamic simulation

Abstract

Groove‐deepening trochleoplasty is performed to restore patellar stability by increasing the lateral constraint applied to the patella by the trochlear groove. Multibody dynamic simulation of knee function was used to characterize the influence of groove‐deepening trochleoplasty on patellar tracking and patellofemoral contact pressures. Computational models were created to represent seven knees with trochlear dysplasia, indicated by a flat trochlear groove and supratrochlear spur. The models were manipulated to remove the spur and deepen the trochlear groove to represent the average shape following a trochleoplasty. Knee squatting was simulated for the preoperative and postoperative conditions. Statistically significant (p < 0.05) differences in output parameters were identified with repeated measures comparisons at every 5° of knee flexion. Trochleoplasty significantly decreased lateral patellar tracking, particularly at low knee flexion angles. Trochleoplasty decreased the peak lateral shift of the patella (bisect offset index) with the knee extended from 0.87 ± 0.14 to 0.75 ± 0.12. Trochleoplasty also significantly decreased the contact area and increased the maximum contact pressure at multiple flexion angles. Trochleoplasty decreased the average contact area by approximately 10% in mid‐flexion, with a corresponding increase in the average maximum contact pressure of 13%–23%. Decreased contact area and increased contact pressures are related to altered patellofemoral congruity due to reshaping the femur without a corresponding change to the patella. Clinical significance: The results indicate groove‐deepening trochleoplasty decreases lateral patellar maltracking, reducing the risk of patellar dislocations, but can elevate patellofemoral contact pressures, which could contribute to long‐term degradation of cartilage.

Computational comparison of medializing tibial tubercle osteotomy and trochleoplasty in patients with trochlear dysplasia

“…Joint mechanics and cartilage stress are also important considerations for the long‐term clinical outcome of a joint stabilizing procedure. A recent computational study evaluated the effect of TP on both lateral patellar tracking and contact mechanics, showing decreased lateral tracking but 13%–23% increase in peak contact pressure 49 . Previous cadaveric and computational studies have reported increases in mean medial trochlear contact pressure with tibial tubercle anteriomedialization, 45,50 while in a cadaveric study, Stephen et al 51 reported attachment location and tensioning during MPFLR altered medial joint contact pressure.…”

“…A recent computational study evaluated the effect of TP on both lateral patellar tracking and contact mechanics, showing decreased lateral tracking but 13%-23% increase in peak contact pressure. 49 Previous cadaveric and computational studies have reported increases in mean medial trochlear contact pressure with tibial tubercle anteriomedialization, 45,50 while in a cadaveric study,…”

The Influence of Surgical Realignment Procedures on Dynamic Patellar Tracking: A Dynamic Magnetic Resonance Imaging-Controlled Feasibility Study

“…Another computational study identified trochlear dysplasia as a direct cause of lateral patellar maltracking [ 53 ]. Accordingly, trochleoplasty was found to decrease lateral patellar shift [ 54 ] and restore patellofemoral congruency [ 55 ]. Despite the consistent findings of these in vitro studies, they are only partially transferable to real patients [ 56 , 57 , 58 ].…”

Adding Tibial Tuberosity Medialization to Medial Patellofemoral Ligament Reconstruction Reduces Lateral Patellar Maltracking During Multidirectional Motion in a Computational Simulation Model

“…The multibody dynamic simulation models and simulated motion (RecurDyn, FunctionBay, Seongnam, Korea) have been described in detail previously. 21 , 25 , 32 , 34 Models were reconstructed from 3.0 T MRI scans of the extended and unloaded knee (proton density weighted, slice thickness ranging from 0.5 mm to 1.5 mm). The femur, patella, and tibia of each model were merged with the corresponding articular cartilage surfaces and represented as separate rigid bodies ( Fig 1 A).…”

“…Loading and boundary conditions were applied to represent a pivot landing on one foot while turning toward the opposite foot 25 (multiplanar unstable motion) and a dual-limb knee squat 21 , 32 , 34 (single-plane stable motion). The loading and boundary conditions were based on in vitro knee flexion rigs.…”