Cement augmentation of an angular stable plate osteosynthesis for supracondylar femoral fractures - biomechanical investigation of a new fixation device

Martin Bäumlein,Christine Klötzer,Benjamin Bücking,Matthias Knobe,Antonio Klasan,Steffen Ruchholtz,Daphne Eschbach,Christopher Bliemel,Benjamin Bockmann

doi:10.1186/s12891-020-03215-3

Abstract

BackgroundImplant anchorage in highly osteoporotic bone is challenging, since it often leads to osteosynthesis failure in geriatric patients with supracondylar femoral fractures. Cementation of screws is presumed to prevent such osteosynthesis failure. This study aimed to investigate the effect of a newly designed, cementable fenestrated condylar screw for plate fixation in a biomechanical setting.MethodsEight pairs of osteoporotic cadaver femora with an average age of 77 years, ranging between 62 and 88 years, were randomly assigned to either an augmented or a non-augmented group. In both groups an instable 33-A3 fracture according to the AO / OTA classification was fixed with an angular stable locking plate. All right samples received a cement augmentation of their fenestrated condylar screws with calcium phosphate bone cement (CPC). Mechanical testing was performed at a load to failure mode by cyclic axial loading, using a servohydraulic testing machine.ResultsWith a mean of 2475 N (95% CI: 1727–3223 N), the pressure forces resulting in osteosynthesis failure were significantly higher in specimen with cemented condylar screws as compared to non-cemented samples (1875 N (95% CI: 1320–2430 N)) (p = 0.024). In both groups the deformation of the constructs, with the distal screws cutting through the condylar bone, were the most frequent cause for failure. Analysis of axial stiffness (p = 0.889) and irreversible deformity of the specimens revealed no differences between the both groups (p = 0.161). No cement leakage through the joint line or the medial cortex was observed.ConclusionBased on the present study results, the newly introduced, cementable condylar screw could be an encouraging feature for the fixation of supracondylar femoral fractures in patients with reduced bone quality in terms of load to failure accuracy of the cement application.

Highlights

Implant anchorage in highly osteoporotic bone is challenging, since it often leads to osteosynthesis failure in geriatric patients with supracondylar femoral fractures
As a further step to previous research [5, 6], the present study focused on a safer and more suitable cement augmentation technique, resulting in the development of a fenestrated condylar screw, suitable for the cement augmentation of angular stable locking plates
Specimens The bones originated from three male and five female adults, with an average age of 77 years

Summary

Introduction

Implant anchorage in highly osteoporotic bone is challenging, since it often leads to osteosynthesis failure in geriatric patients with supracondylar femoral fractures. Cementation of screws is presumed to prevent such osteosynthesis failure. An osteoporotic bone structure often contributes to the occurrence of such distal femoral fractures in these patients [2, 3]. To improve fracture fixation in the old aged, polyaxial, angular stable implants as well as new, minimally invasive operation techniques have been developed. Notwithstanding such innovations in implant technology and soft tissue management, the fixation of far distally located femoral factures still remains problematic, especially in severely osteoporotic bone [4]. In the last few years, cement augmentation of implants gained more and more popularity to improve implant anchorage

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