Computational approach to correcting joint instability in patients with recurrent patellar dislocation

Abstract

Patellar dislocation is a debilitating injury common in active adolescents and young adults. Conservative treatment after initial dislocation is often recommended, but almost half of these patients continue to suffer from recurrent dislocation. The objective of this study was to compare preoperative patellofemoral joint stability with stability after a series of simulated procedures, including restorative surgery to correct to pre‐injury state, generic tibial tubercle osteotomy, patient‐specific reconstructive surgery to correct anatomic abnormality, less invasive patient‐specific surgery, and equivalent healthy controls. Three‐dimensional, subject‐specific finite element models of the patellofemoral joint were developed for 28 patients with recurrent patellar dislocation. A 50 N lateral load was applied to the patella to assess the lateral stability of the patellofemoral joint at 10° intervals from 0° to 40° flexion. Medial patellofemoral ligament reconstruction, along with reconstructive procedures to correct anatomic abnormality were simulated. Of all the simulations performed, the healthy equivalent control models showed the least patellar internal–external rotation, medial–lateral translation, and medial patellofemoral ligament restraining load during lateral loading tests. Isolated restorative medial patellofemoral ligament reconstruction was the surgery that resulted in the most patellar internal–external rotation, medial–lateral translation, and medial patellofemoral ligament reaction force across all flexion angles. Patient‐specific reconstruction to correct anatomic abnormality was the only surgical group to have non‐significantly different results compared with the healthy equivalent control group across all joint stability metrics evaluated. Statement of clinical significance: This study suggests patient‐specific reconstructive surgery that corrects underlying anatomic abnormalities best reproduces the joint stability of an equivalent healthy control when compared with the pre‐injury state, generic tibial tubercle osteotomy, and less invasive patient‐specific surgery. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:768‐776, 2020

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

“…Knee geometry for each subject was aligned to a local femoral coordinate system using an iterative closest point algorithm implemented in MATLAB (Mathworks). A dynamic three-dimensional FE model, based on previous publications, 23,24 was developed in Abaqus/Explicit (Simulia). In brief, the model includes femur, tibia, and patella bones, femoral, tibial, and patellar articular cartilage, patellar tendon and quadriceps tendon and muscle.…”

“…MPFLR force (where applicable), patella M-L shift and I-E rotation were compared between surgical groups. MPFL representation and mTTO and TP simulation were implemented as described previously 24 and summarized briefly here.…”

“…8,35 TP was simulated using radial basis functions (RBF) to morph the femoral trochlear geometry to deepen the sulcus. 24,36 The sulcus angle was measured in the axial plane at the level of the most anterior prominence of the lateral ridge of the trochlear groove. The sulcus angle at this part of the groove was morphed to create a sulcus angle of 138°, the average angle reported in a control population.…”

“…17,38,39 The results from this analysis support that approach-patellar stability after both mTTO and TP simulations benefited significantly from the inclusion of the MPFL. Most computational evaluations of patellar stability have used a single kinematic condition per knee 18,24,40 -however, this study assesses the robustness of patellar joint stability to kinematic variability. When performing cadaveric or computational analyses to quantify the effectiveness of a particular procedure on patellar stability, it is important to evaluate this procedure over a variety of kinematic and loading conditions, rather than a single deterministic set of conditions, to ensure that the procedure is robust to variation encountered across the patient population.…”

Anatomical Components Associated With Increased Tibial Tuberosity–Trochlear Groove Distance

“…Recurrent lateral patellar dislocation (LPD) is a debilitating musculoskeletal disorder among children and adolescents, especially in young female patients. 2 The incidence of LPD ranges up to 43 per 100,000, accounting for 2% to 3% of knee injuries. 4 The reported anatomical risk factors for LPD include trochlear dysplasia, patellar alta, increased tibial tuberosity–trochlear groove (TT-TG) distance, rotational deformity, and medial patellofemoral ligament insufficiency.…”