Transpatellar bone tunnels perforating the lateral or anterior cortex increase the risk of patellar fracture in MPFL reconstruction: a finite element analysis and survey of the International Patellofemoral Study Group

Abstract

Purpose (1) To determine applied patellar drilling techniques for medial patellofemoral ligament (MPFL) reconstruction among members of the International Patellofemoral Study Group (IPSG) and (2) to evaluate the risk of patellar fracture for various patellar bone tunnel locations based on a inite element analysis (FEA) model. Methods In the irst part of the study, an online survey on current MPFL reconstruction techniques was conducted among members of the IPSG. In the second part of the study, a three-dimensional FEA model of a healthy knee joint was created using a computed tomography scan. Patient-speciic bone density was integrated into the patella, and cartilage of 3 mm thickness was modeled for the patellofemoral joint. According to the survey's results, two diferent types of patellar bone tunnels (bone socket and transpatellar bone tunnel) were simulated. The risk of patellar fracture was evaluated based on the fracture risk volume (FRV) obtained from the FEA. Results Finite element analysis revealed that subchondral bone socket tunnel placement is associated with the lowest FRV but increased with an anterior ofset (1-5 mm). Transpatellar bone tunnels violating the lateral or anterior cortex showed a higher FRV compared to bone socket, with the highest values observed when the anterior cortex was penetrated. Conclusion Violation of the anterior or lateral patellar cortex using transpatellar bone tunnels increased FRV compared to a subchondral patellar bone socket tunnel. In MPFL reconstruction, subchondral patellar bone socket tunnels should be considered for patellar graft ixation to avoid the risk of postoperative patellar fracture. Level of evidence Survey; Descriptive laboratory study/Level V.

Computational evaluation of wire position using separate vertical wire technique and candy box technique for the fixation of inferior pole patellar fractures: a finite element analysis

“…The results of the second part of this study indicate that the steel wire experienced minimal stress in both the steel wire and patellar when passing through position p6, which aligns with previous biomechanical research ( Wierer et al, 2022 ). Additionally, it was observed that p1 had the smallest maximum displacement value under different forces.…”

Candy box technique for the fixation of inferior pole patellar fractures: finite element analysis and biomechanical experiments

“…Because the internal fixation method in the CB technique goes through the patellar tunnel, it is noteworthy that a 2018 cadaver study showed that when penetrating the bone tunnel, destruction of the anterior cortex increases the risk of patellar fracture [ 35 ]. This was subsequently confirmed in a finite element analysis of the patellar tunnel [ 36 ]. In addition, a finite element analysis of the insertion position of the Kirschner wire showed that the more backward the Kirschner wire, the more stable the fracture [ 37 ].…”

Previous Extensor Mechanism Repair Is Associated With Increased Rates of Surgical Complications Following Total Knee Arthroplasty: A Propensity-matched Analysis

“…Notably, previous, aforementioned studies did not find an increase in fracture risk following TKA in cohorts of patients with prior soft-tissue or bony periarticular knee procedure. One possible etiology for an increased risk of fracture may be associated with the fixation since many extensor mechanism repairs rely on bone tunnels which can be prone to fracture and cortical wall blowout [ 16 , 17 ].…”