Abstract
Background and Objectives: Hip fractures constitute the most debilitating complication of osteoporosis with steadily increasing incidences in the aging population. Their intramedullary nailing can be challenging because of poor anchorage in the osteoporotic femoral head. Cement augmentation of Proximal Femoral Nail Antirotation (PFNA) blades demonstrated promising results by enhancing cut-out resistance in proximal femoral fractures. The aim of this study was to assess the impact of augmentation on the fixation strength of TFN-ADVANCEDTM Proximal Femoral Nailing System (TFNA) blades and screws within the femoral head and compare its effect when they are implanted in centre or anteroposterior off-centre position. Materials and Methods: Eight groups were formed out of 96 polyurethane low-density foam specimens simulating isolated femoral heads with poor bone quality. The specimens in each group were implanted with either non-augmented or cement-augmented TFNA blades or screws in centre or anteroposterior off-centre positions, 7 mm anterior or posterior. Mechanical testing was performed under progressively increasing cyclic loading until failure, in setup simulating an unstable pertrochanteric fracture with a lack of posteromedial support and load sharing at the fracture gap. Varus-valgus and head rotation angles were monitored. A varus collapse of 5° or 10° head rotation was defined as a clinically relevant failure. Results: Failure load (N) for specimens with augmented TFNA head elements (screw/blade centre: 3799 ± 326/3228 ± 478; screw/blade off-centre: 2680 ± 182/2591 ± 244) was significantly higher compared with respective non-augmented specimens (screw/blade centre: 1593 ± 120/1489 ± 41; screw/blade off-centre: 515 ± 73/1018 ± 48), p < 0.001. For both non-augmented and augmented specimens failure load in the centre position was significantly higher compared with the respective off-centre positions, regardless of the head element type, p < 0.001. Augmented off-centre TFNA head elements had significantly higher failure load compared with non-augmented centrally placed implants, p < 0.001. Conclusions: Cement augmentation clearly enhances the fixation stability of TFNA blades and screws. Non-augmented blades outperformed screws in the anteroposterior off-centre position. Positioning of TFNA blades in the femoral head is more forgiving than TFNA screws in terms of failure load.
Highlights
The high morbidity and mortality rates of osteoporotic fracture patients are wellknown
The specimens were assigned to eight study groups consisting of twelve specimens each (n = 12) and differing in blade or screw cephalic implantation, centre or anteroposterior off-centre implant positioning, and bone cement augmentation (Table 1)
No further significant differences were identified among the off-centre position, the TM Proximal Femoral Nailing System (TFNA) screw demonstrated a 420% increase in failure load studyIngroups
Summary
The high morbidity and mortality rates of osteoporotic fracture patients are wellknown. Despite the recent advances in implant design development, the reported rates of implant-related failures remain in the range of 2.0–16.5% [7,8] Most of these failures are due to the underlying poor bone stock or cephalic implant malposition leading to cut-out and varus collapse [9]. These types of complications often require a reintervention and need to be avoided in an already vulnerable population of hip fracture patients. Hip fractures constitute the most debilitating complication of osteoporosis with steadily increasing incidences in the aging population Their intramedullary nailing can be challenging because of poor anchorage in the osteoporotic femoral head.
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