Periprosthetic femoral fracture fixation: A biomechanical comparison between proximal locking screws and cables

Abstract

Background: The incidence of periprosthetic femoral fractures (PFF) around a stable stem is increasing. The aim of this biomechanical study is to examine how three different methods of fixation, for Vancouver type B1 PFF, alter the stiffness and strain of a construct under various configurations in order to gain a better insight into the optimal fixation method. Methods:Three different combinations of proximal screws and Dall-Miles cables were used: (A) proximal unicortical locking screws alone; (B) proximal cables and unicortical locking screws; (C) proximal cable alone, each in combination with distal bicortical locking screws, to fix a stainless steel locking compression plate to five synthetic femora with simulated Vancouver type B1 PFFs. In one synthetic femora there was a 10mm fracture gap, in order to simulate a comminuted injury. The other four femora had no fracture gap, to simulate a stable injury. An axial load was applied to the constructs, at varying degrees of adduction and the overall construct stiffness and surface strain were measured.Results: With regards to the stiffness, in both the gap and no gap models, method of fixation A was the stiffest form of fixation. The inclusion of the fracture gap reduced the stiffness of the construct quite considerably for all methods of fixation. The strain, across both the femur and the plate, was considerably less for method of fixation C, compared to A and B at the locations considered in this study. Conclusion:This study highlights that the inclusion of cables appears to damage the screw fixations and does not aid in the construct stability. Furthermore, the degree of fracture reduction affects the whole construct stability and the bending behaviour of the fixation.

Combined Surgical And Medical Treatment For Periprosthetic Femoral Fractures Over A Stable Stem (Vancouver Type B1 And C): A Proposal Of A Therapeutic Algorithm To Reduce The Risk Of Nonunion.

“…As for mechanical criteria, these are already well known. Characteristics of the fracture and type of hardware have been evaluated, with biomechanical studies [60,[62][63][64][65][66][67][68][69] con rming clinical remarks. The use of bicortical screws around the stem is preferable over cerclages alone or cerclages plus monocortical screws, even if a recent clinical study showed no differences in results when only proximal cables where used with a non-locking plate [70].…”

Periprosthetic fracture fixation of the femur following total hip arthroplasty: A review of biomechanical testing – Part II

“…In respect to loading modes and surrounding conditions, higher loading modes have been used by several authors. In previous studies (Moazen et al, 2011), only 500 N could be seen used repeatedly for non-destructive monotonic tests; in present studies, loads of 700 N (Choi et al, 2010;Graham et al, 2015) to 2500 N (Pletka et al, 2011) have been used. A loading mode not seen in previous papers is fourpoint bending (Lenz et al, 2016a(Lenz et al, , 2016bLever et al, 2010;Lochab et al, 2017) and in one case three-point bending (Choi et al, 2010); examples of these can be seen in Fig.…”

“…Distal part of femur is potted in PMMA cement (Lenz et al, 2012a). (Choi et al, 2010;Giesinger et al, 2014;Graham et al, 2015;Griffiths et al, 2015;Gwinner et al, 2015;Konstantinidis et al, 2010;Lochab et al, 2017;Sariyilmaz et al, 2014;Shah et al, 2011). B) No gap (Brand et al, 2014;Frisch et al, 2015;Griffiths et al, 2015;Hoffmann et al, 2014;Konstantinidis et al, 2017;Lehmann et al, 2010;Lenz et al, 2012aLenz et al, , 2012bLenz et al, , 2016aLever et al, 2010;Pletka et al, 2011).…”

“…In many studies, no fracture gap was left after the osteotomy, in order to simulate a stable fracture pattern (Brand et al, 2014;Frisch et al, 2015;Griffiths et al, 2015;Hoffmann et al, 2014;Konstantinidis et al, 2017;Lehmann et al, 2010;Lenz et al, 2012aLenz et al, , 2012bLenz et al, , 2016aLever et al, 2010;Pletka et al, 2011). Other studies implemented a fracture gap (where the femur was not fixed as if anatomically reduced, and a gap was left between the fracture), typically below the tip of the hip stem prosthesis; fracture gap implemented ranged from 5 mm to 20 mm (Choi et al, 2010;Giesinger et al, 2014;Graham et al, 2015;Griffiths et al, 2015;Gwinner et al, 2015;Konstantinidis et al, 2010;Lochab et al, 2017;Sariyilmaz et al, 2014;Shah et al, 2011). Fracture gaps were typically used to mimic a fragmented fracture model (Sariyilmaz et al, 2014).…”

Proximale periprothetische Femurfrakturen: Klassifikation und Therapie

“…Inwieweit zusätzlich kortikale Allografts, die an einigen Zentren zur Anwendung kommen, notwendig sind, hängt von der Verfügbarkeit, der Defektsituation, aber auch von der Erfahrung und dem Zugang des Chirurgen ab. Zudem sind diese Allografts kritisch zu bewerten, sie führen zu einer Erhöhung der kortikalen Dicke und erhöhen auch das Infektionsrisiko[20,[50][51][52][53][54][55][56][57][58][59].Mögliche weitere Entwicklungen zur Versorgung von periprothetischen FrakturenSpeziell die periprothetischen Frakturen beim alten Patienten mit Osteoporose, aber stabilen Vancouver-B1-und -C-Frakturen zeigen oft nur eine eierschalenartige, dünne Knochenschicht im Bereich der Prothese. In dieser Situation ist es sehr schwierig, stabile Schrauben zu setzen, Cerclagen alleinwie zuvor ausgeführtsind oft unzureichend.…”