A Biomechanical Study Comparing Helical Blade with Screw Design for Sliding Hip Fixations of Unstable Intertrochanteric Fractures

Abstract

Dynamic hip screw (DHS) is a well-established conventional implant for treating intertrochanteric fracture. However, revision surgery sometimes still occurs due to the cutting out of implants. A helical blade instead of threaded screw (DHS blade) was designed to improve the fixation power of the osteoporotic intertrochanteric fracture. In this study, the biomechanical properties of DHS blade compared to the conventional DHS were evaluated using an unstable AO/OTA 31-A2 intertrochanteric fracture model. Fifty synthetic proximal femoral bone models with such configuration were fixed with DHS and DHS blade in five different positions: centre-centre (CC), superior-centre (SC), inferior-center (IC), centre-anterior (CA), and centre-posterior (CP). All models had undergone mechanical compression test, and the vertical and rotational displacements were recorded. The results showed that DHS blade had less vertical or rotational displacement than the conventional DHS in CC, CA, and IC positions. The greatest vertical and rotational displacements were found at CP position in both groups. Overall speaking, DHS blade was superior in resisting vertical or rotational displacement in comparison to conventional DHS, and the centre-posterior position had the poorest performance in both groups.

A biomechanical comparison of two cephalomedullary nails; one using a single lag screw with antirotator blade and a nail using two lag screws for unstable intertrochanteric fractures

“…13,17,18 But we believe that this situation doesn't simulate the real stance. Because load to failure under such a condition eventually leads a failure from femoral head.…”

“…Theoretically it offers the potential of resisting rotation and a better holding power in osteoporotic femoral head with compaction of cancellous bone and can decrease the rate of cutting out. 13,14 As a matter of fact, several clinical and experimental studies were published after ıntroduction of the single helical blade. Although studies comparing two lag screws with a single helical blade concluded the biomechanical and clinical superiority of single helical blade.…”

“…Although studies comparing two lag screws with a single helical blade concluded the biomechanical and clinical superiority of single helical blade. 3,[13][14][15] There are still unresolved problems like lack of compression with blade and more lateral migration when compared with telescoping screws. 16 The aPFN have been developed from this point of view.…”

“…First, although third generation synthetic bones are validated in use of biomechanical tests comparing biomechanical properties of two different implants, it would be better if the test was done using cadaveric bones. 13 Although study reflects the biomechanical properties of two different designs of cephalomedullary nails, it should have been better if the failure test was done using cyclical loading which had been more similar to physiological loading of daily activities. Only axial loading was performed which makes it harder to draw conclusions about endurance and biomechnical properties of implants under bending and torsional forces.…”

Extra- vs. intramedullary treatment of pertrochanteric fractures: a biomechanical in vitro study comparing dynamic hip screw and intramedullary nail

“…Since the DHS blade shows a higher rotational stability and resistance to push out compared to the conventional screw [16,17], we decided to use the helical blade to achieve the most stable conditions for the extramedullary osteosynthesis. Furthermore, an additional, angular stable, trochanteric stabilization plate was implanted to ensure maximum stability.…”