Biomechanical comparison of dynamic condylar screw and locking compression plate fixation in unstable distal femoral fractures: An in vitro study

Abstract

Background:Distal femur fractures are difficult to manage and the selection of implant for internal fixation remains controversial. The objective of this study is to establish the relative strength of fixation of a distal femoral locking plate (DFLP) compared with the dynamic condylar screw (DCS) in the distal femur fractures.Materials and Methods:Study was conducted on 16 freshly harvested cadaveric distal femoral specimens, eight implanted with DCS and other eight with DFLP. The construct was made unstable by removing a standard sized medial wedge of 1 cm base (gap-osteotomy) beginning 6 cm proximal to the lateral joint line in distal metaphyseal region with the loss of medial buttress. Fatigue test was conducted under load control mode at the frequency of I Hz. Specimens were subjected to cyclic loading of 2 kN, under observation for 50,000 cycles or until failure/cutout, which ever occurred earlier.Results:In DFLP group, there was no implant failure and the average number of cycles sustained was 50,000. Six out of eight specimens completed 50,000 cycles and two failed in DCS group. The average number of cycles sustained by DCS was 46150. Though the bone quality as assessed by dual energy X-ray absorptiometry DEXA was comparable in both DFLP and DCS group (P = 0.06), none failed in DFLP group and subsidence was 1.02 ± 0.34 mm (range: 0.60-1.32 mm), which was significantly 43% lower (P = 0.006) than subsidence in DCS group (1.82 ± 0.58; range: 1.20-3.08 mm). The average stiffness of DCS group was 52.8 ± 4.2 N/mm, which was significantly lower than average stiffness of locked condylar plate group (71.2 ± 5.1 N/mm) (P = 0.02).Conclusions:DFLP fixation of the distal femur fractures resulted in stronger construct than the DCS fixation in both cyclic loading and ultimate strength in biomechanical testing of a simulated A3 distal femur fracture.

Estudo comparativo da resistência mecânica da força de compressão entre biomateriais naturais, sintéticos e mistos

“…Para isso, torna-se necessário a realização de ensaios mecânicos específicos, que depende do tipo de material a ser testado, da finalidade a que se destina, do tipo de esforço ao qual será submetido e, também, das propriedades do biomaterial (França et al 2008, Singh et al 2013, Ueno et al 2015. Como o esqueleto apendicular dos animais está sob ação de um conjunto de forças, dentre elas a de compressão, o teste mecânico de compressão axial, atualmente, é o mais utilizado para avaliar a resistência mecânica de biomaterial, principalmente os cilíndricos (Amendola et al 2008, Alves et al 2010, Sonagli et al 2011.…”

Assessment of Outcomes of Treatment of Fractures of Distal Femur with a Locking Plate Taking into Account Factors Influencing the Result

“…Locking plates, together with angled blade plates, intramedullary nails and DCS plates, have become one of the most commonly used fixation devices in DFFs [5]. A biomechanical comparison of locking plates and DCS plates shows locking plates to be more stable [6]. Biomechanical studies of digital models have shown that the stability of a DFF fixa tion ły, że sta bil ność ze spo le nia ZKD KU pły ta mi blo kowa ny mi, po zwa la na wdro że nie czyn nych ćwi czeń sta wu ko la no we go w pierw szych dniach po ope ra cji bez ry zy ka za bu rze nia zro stu i de sta bi li za cji ze spo lenia [7].…”

“…Pły ty blo ko wa ne sta ły się obok płyt ką to wych, gwoź dzi śród sz pi ko wych i płyt DCS, jed nym z częściej sto so wa nych ma te ria łów do ze spo le nia ZKD -KU [5]. Bio me cha nicz ne po rów na nie płyt blo ko wanych i płyt DCS wy ka zu je, że pły ty blo ko wa ne są sta bil niej szą kon struk cją [6]. Ba da nia bio me cha niczne prze pro wa dzo ne na mo de lach cy fro wych wy ka za -returning to work.…”

Effects of smoking on healing of distal femur intra-articular fractures, treated with distal femur locking compression plate

“…Locking plates provides an additional advantage of angular stability of locked screws by which applied load is evenly distributed amongst the component screws and avoids significant load concentration at a single screw bone interface [4,6,7]. This leads to the overall Original Article fixation strength of the locked plate system, equaling the sum of fixation strengths of all screw bone interfaces instead of that of a single component screw as in conventional plating [8].…”

“…Voluminous literature [8][9][10] is available showing good to excellent results of locking plates for the treatment of distal femur fracture however none of study has compared the outcome of patients in smoker and nonsmoker. Since smoking affects the bone union time therefore this study was carried out to assess the long term functional outcome of distal femur fracture treated with locking plates and compared the outcome results among smokers and nonsmokers.…”