A Mechanical Comparison of the Compressive Force Generated by Various Headless Compression Screws and the Impact of Fracture Gap Size

Abstract

Background: There is evidence that interfragmentary fracture gap size may affect the compression achievable with a modern headless compression screw (HCS). This mechanical study compared the compression achieved by 3 commercial HCS systems through various fracture gaps: CAPTIVATE Headless (Globus Medical, Inc, Audubon, Pennsylvania), Synthes (DePuy Synthes, Westchester, Pennsylvania), and Acumed Acutrak 2 (Acumed LLC, Hillsboro, Oregon). Methods: Screws were inserted into a custom test fixture composed of polyurethane synthetic bone foam fragments, separated by a layer of easily compressible polyurethane foam simulating a fracture gap. Compression was measured after final insertion and countersinking. The effect of the interfragmentary fracture gap size on the compression generated was also investigated. Results: The CAPTIVATE Headless 3.0 mm screw (70.1 ± 5.7 N) and the Synthes 3.0 mm screw (64.9 ± 7.3 N) achieved similar compressive forces after final countersink. Similar comparisons were found for the CAPTIVATE Headless 2.5 mm and Synthes 2.4 mm screws, and the CAPTIVATE Headless 4.0 mm and Acutrak 2 Standard screws. The final compression of the CAPTIVATE Headless 2.5 mm and Synthes 2.4 mm screws was not significantly affected when the fracture gap was doubled from 2 to 4 mm, but was reduced significantly by 95.9% with the Acutrak 2 Micro screw. Conclusion: When comparing like-sized screws, the CAPTIVATE, Synthes, and Acutrak 2 HCS systems demonstrated similar potential compressive forces. However, compared with the CAPTIVATE Headless and Synthes HCS systems, which are inserted with a compression sleeve that is not gap distance–dependent, the Acutrak 2 HCS system demonstrated less compression when the simulated fracture gap size was increased to 4 mm.

Experimental Characterization and Numerical Modeling of the Corrosion Effect on the Mechanical Properties of the Biodegradable Magnesium Alloy WE43 for Orthopedic Applications

“…According to Ilyas, Mahoney and Bucklen [ 35 ], the compressive force involved in fracture fixation when it is using Ø2.4 mm orthopedic screws, equivalent to the screw object of the present case study, is of the order of 65 to 70 N; thus, it is assumed that the screw is able to sustain the loads necessary for the correct stabilization of fractures until a degradation of approximately 30% to 35% of mass loss [ 22 ]. However, it is important to emphasize that the model in question does not take into account the regeneration and adhesion of bone tissue in the regions adjacent to the orthopedic screw, which could result in changes in the pull-out forces found in vivo.…”

Biomechanical comparison of headless compression screws versus independent locking screw for intra-articular fractures

“…In our study, we maintained a short fracture gap (0.8 mm) to ensure that the impact of fracture gap was limited from affecting the results. Previous studies have shown that Acutrak screws will generate less compression force with larger fracture gaps [ 1 , 6 , 8 ].…”

“…However, peri-articular bone has a mixture of hard subchondral bone as well as cancellous bone. Previous studies have also acknowledged this as a limitation of bone model studies [ 1 , 8 ].…”

“…The Acutrak screw (Acumed LLC, Hillsboro, Oregon) is a tapered cannulated HCS with a variable pitch along the full length of the screw [ 7 ]. Other second-generation screws evolved on the principles of increased compressive strength and improved versatility such as the CAPTIVATE HCS (Globus Medical Inc, Audubon, Pennsylvania) [ 8 ] and Synthes HCS (DePuy Synthes, West Chester, Pennsylvania) [ 1 , 5 , 9 ]. These second-generation HCSs allow for good compressive forces and percutaneous fixation which is important for smaller intra-articular fractures, such as fractures of the scaphoid [ 3 , 10 , 11 ].…”

“…Our hypothesis is that locking screws generate comparable compressive forces to HCSs. Previous studies have been conducted comparing various HCSs available [ 1 , 3 , 8 , 11 , 15 – 17 ] and a previous study by Felstead et al [ 12 ] demonstrated that locking screws can be used for intra-articular elbow fractures. However, biomechanical studies have not been conducted comparing the compression forces generated between a second-generation HCS and an independent locking screw of similar specifications.…”