Locking compression plate breakage and fracture non-union: a finite element study of three patient-specific cases

Abstract

Background & purpose The locking compression plate (LCP) system oVers a number of advantages in fracture Wxation combining angular stability through the use of locking screws with traditional Wxation techniques. However, the system is complex, requiring careful attention to biomechanical principles and good surgical technique. Methods From a series of clinical cases, where locking plate Wxation was used in fractures of long bones, three were selected. Patient-speciWc geometric information was obtained from AP and lateral plain radiographs, and the Finite Element (FE) models were generated manually. Results The Wrst case study highlighted the importance of the working length on the construct stability. By increasing the working length, the construct became more Xexible. The resulting increase in interfragmentary motion promoted indirect healing with the formation of callus. In the second case study, plate breakage occurred as a result of an inappropriate Wxation technique. The Wxation involved the use of locked screws at the level of the fracture passing the fracture line. This reduced the Xexibility of the implant which hindered the micro-motion needed for callus formation. Fatigue failure eventually occurred due to cyclic loading past the yield stress of the LCP. In the third case study, the long working length of the construct made it relatively Xexible. The larger area of stress distribution on the plate reduced the local strain, resulting in a protective eVect against fatigue failure of the implant. Interpretation In Conclusion, successful application of the LCP demands a good understanding of the biomechanics and careful preoperative planning.

Bringing computational models of bone regeneration to the clinic

“…Similarly, Moazen et al concluded that the bridging length made a more substantial difference to the stiffness and interfragmentary movement than varying the plate material, plate thickness, or screw‐plate fixation . Also Nassiri et al have recently reported similar findings . The calculations of Boccaccio et al indicated that the presence of percutaneous fixation devices significantly shortened the healing times of the fractured body of the L4 vertebra .…”

Computational modelling of long bone fractures fixed with locking plates – How can the risk of implant failure be reduced?

“…Hardware failure (plate failure, or screw breakage) is a complication that has been reported to occur in as many as 18% of plate fixations, 17 often as a result of an inappropriate fixation technique, rather than the choice of plate.…”

“…The use of locked screws at the level of the fracture passing through the fracture line and short working lengths are examples of such inappropriate techniques, 17 as it reduces the flexibility of the implant 8 which hinders the micromotion needed for callus formation.…”

Locked Compression Plating for Peri‐ and Intra‐articular Fractures Around the Knee

“…They give excellent clinical and functional results in management of peri‐ and intra‐articular fractures provided they are applied with proper understanding of biomechanics; however, their advantages appear to be offset by difficulties in fracture reduction and plate application. Working length and position of screws are the most crucial factors for preventing implant failure and nonunion. An increase in working length increases inter fragmentary motion in comminuted fractures and also distributes stress over a large area.…”