Metacarpal shaft fixation: a biomechanical comparison of dorsal plating, lag screws, and headless compression screws

Abstract

Background Metacarpal shaft fractures are common and can be treated nonoperatively. Shortening, angulation, and rotational deformity are indications for surgical treatment. Various forms of treatment with advantages and disadvantages have been documented. The purpose of the study was to determine the stability of fracture fixation with intramedullary headless compression screws in two types of metacarpal shaft fractures and compare them to other common forms of rigid fixation: dorsal plating and lag screw fixation. It was hypothesized that headless compression screws would demonstrate a biomechanical stronger construct. Methods Five matched paired hands (age 60.9 ± 4.6 years), utilizing non-thumb metacarpals, were used for comparative fixation in two fracture types created by an osteotomy. In transverse diaphyseal fractures, fixation by headless compression screws (n = 7) and plating (n = 8) were compared. In long oblique diaphyseal fractures, headless compression screws (n = 8) were compared with plating (n = 8) and lag screws (n = 7). Testing was performed using an MTS frame producing an apex dorsal, three point bending force. Peak load to failure and stiffness were calculated from the load-displacement curve generated. Results For transverse fractures, headless compression screws had a significantly higher stiffness and peak load to failure, means 249.4 N/mm and 584.8 N, than plates, means 129.02 N/mm and 303.9 N (both p < 0.001). For long oblique fractures, stiffness and peak load to failure for headless compression screws were means 209 N/mm and 758.4 N, for plates 258.7 N/mm and 518.5 N, and for lag screws 172.18 N/mm and 234.11 N. There was significance in peak load to failure for headless compression screws vs plates (p = 0.023), headless compression screws vs lag screws (p < 0.001), and plates vs lag screws (p = 0.009). There was no significant difference in stiffness between groups. Conclusion Intramedullary fixation of diaphyseal metacarpal fractures with a headless compression screw provides excellent biomechanical stability. Coupled with lower risks for adverse effects, headless compression screws may be a preferable option for those requiring rapid return to sport or work. Level of evidence Basic Science Study, Biomechanics.

Intramedullary K-wires versus Alternate Techniques for Metacarpal Shaft and Neck Fractures: A Systematic Review and Meta-analysis

“…45 Purported advantages of IMS are early mobilization and no pin-site or soft tissue morbidity. 47 49 50 Compared with plate fixation, IMS may also allow for a faster return to work or sports, with reduced risk of adverse events because of a rigid fixation. 49 While both clinical and biomechanical studies support the utilization of IMS for unstable metacarpal fractures, 46 47 48 49 50 51 more prospective clinical trials are needed to provide evidence for IMS over IMKW and to investigate the effect of tendon, capsule, and cartilage injury during screw insertion.…”

“…2,[45][46][47][48] However, metacarpophalangeal joint stiffness and extension lag are the reported complications with IMS 45. Purported advantages of IMS are early mobilization and no pin-site or soft tissue morbidity 47,49,50. Compared with plate fixation, IMS may also allow for a faster return to work or sports, with reduced risk of adverse events because of a rigid fixation 49.…”

Comparison of the fixation ability between lag screw and bone plate for oblique metacarpal shaft fracture

“…Previous studies have adopted in vitro experiments for metacarpal fracture fixation, human cadaveric bones [ 22 ], animal bones [ 7 ], or artificial bones [ 8 , 12 – 14 ]. We employed artificial metacarpal bone because fresh human metacarpal bones were difficult to obtain and because some literature and the American Society for Testing and Materials had used artificial bones for experiments.…”

“…The load to failure of the experiment was 72.31 N, which was much lower than that of double lag screw fixation in the present study (153.6 N). [ 22 ] compared the fixation strength of dorsal plating, lag screw fixation, and headless compression screw fixation and revealed that headless compression screw fixation offered the most satisfactory fixation. The maximum fracture force and stiffness of the double lag screw fixation were 234.1 N and 172.18 N/mm, respectively, which were much higher than our results (153.6 N and 57.0 N/mm, respectively).…”

Biomechanical study on fixation methods for horizontal oblique metacarpal shaft fractures

“…Therefore, most hand surgeons do not consider K-wire fixation to be suitable for the treatment of oblique metacarpal fractures. Lag screw fixation is a less invasive surgical procedure and typically results in favorable outcomes [ 27 ]. However, the uncertain mechanical stability of fixing by using only lag screws and the precise surgical technique required to place lag screws are major concerns for surgeons [ 27 ].…”