A Biomechanical and Clinical Comparison of Midshaft Clavicle Plate Fixation: Are 2 Screws as Good as 3 on Each Side of the Fracture?

Abstract

Background:The standard of care for plating displaced midshaft clavicle fractures has been 6 cortices of purchase on each side of the fracture. The use of locking plates and screws may afford equivalent biomechanical strength with fewer cortices of purchase on each side of the fracture.Purpose:To compare the biomechanical and clinical performance of 3- versus 2-screw constructs for plating displaced midshaft clavicle fractures.Study Design:Controlled laboratory study/cohort study; Level of evidence, 3.Methods:Lateral fragments of simulated midshaft fractures in 10 pairs of cadaveric clavicles were randomly assigned to plate fixation with either 3 nonlocking screws or 2 locking screws. Cyclic tensile loads were applied along the long axis of the clavicle. The constructs were then loaded to failure with pullout forces applied parallel to the long axis of the screws. Additionally, clinical outcomes of patients who had midshaft clavicle fractures that were surgically repaired were retrospectively identified and compared; 21 patients were treated with 3-screw constructs and 20 with 2-screw constructs.Results:Biomechanically, there were no significant differences for cyclic displacement, stiffness, yield load, or ultimate load between groups. Forces required for screw pullout were considerably higher than physiologic forces experienced by a healing clavicle in vivo. Clinically, there were no significant differences in American Shoulder and Elbow Surgeons, Constant, visual analog scale, and Single Assessment Numeric Evaluation scores; complications; or mean time to union. Additionally, we found that the plates used in the 2-screw group were consistently shorter.Conclusion:Plate fixation of displaced midshaft clavicle fractures with 4 cortices of purchase with 2 locking screws demonstrated no significant differences biomechanically when compared with fixation with 6 cortices of purchase and 3 nonlocking screws. Clinically, there were no significant differences in outcomes or complications seen in patients receiving 2- or 3-screw constructs.Clinical Relevance:Clinical benefits of using the 3-screw construct for plate fixation include decreased surgical exposure, morbidity, and cost, and the use of shorter and noncontoured straight plates eliminates the extra time and technical difficulty associated with matching longer contoured plates to the complex morphology of the clavicle.

Evaluation and Management of Midshaft Clavicle Fractures in Adolescents

“…Open reduction and internal fixation with plate and screw constructs (Figure 2) remain the most frequent choice of operative fixation. There is ongoing investigation [36][37][38][39][40][41] into optimal plate location (superior vs. anteroinferior), screw type (locking vs. nonlocking), screw placement (unicortical vs. bicortical), screw number (4 cortices vs. 6 cortices), plate number (single vs. dual-plating), and plate size (2.7 mm vs. 3.5 mm), with minimal rigorous comparisons in the pediatric and adolescent literature. Manufacturer pre-contoured specialty clavicle plates may lead to decreased plate prominence and subsequent lower rates of implant removal.…”

Comparing internal fixation constructs for scapular spine insufficiency fractures following reverse shoulder arthroplasty

“…7 As such, in our study, we chose to test several different locking plate constructs that varied in plate positioning and in the presence or absence of a lateral acromial supporting hook. 2,4,5,8,12,15 When examining our results for medial fixation, placing the locking plate on the dorsal subcutaneous border of the scapular spine was less likely to fail than plate placement within the supraspinatus fossa. In retrospect, this is intuitive given that the placement of the plate over the dorsal subcutaneous border allowed for longer locking screws that were directed intracortically along the height of the scapular spine to reach the anterior cortex of the scapula body.…”

Biomechanical and clinical evaluation of minimal invasive plate osteosynthesis for two-part clavicle shaft fractures

“…However, human motion is more complex, which might make this model considered unfavorable. Screw pullout, a common clinical complication, cannot be adequately simulated and fractures often occur adjacent to the plate [ 27 ]. This was also the finding in our study, where in the most cases a fracture occurred at the medial edge of the plate.…”

“…There are also several studies that have investigated biomechanical differences between 2- and 3-screw treatments per fracture side. Larsen et al examined the question by using a 7-hole midshaft clavicle plate (Arthrex) and biomechanically found no significant differences for cyclic displacement, stiffness, yield load or ultimate load between the groups [ 27 ]. However, the study used a different experimental setup on one hand and a different type of fixation and implant (3 non-locking vs. 2 locking screws per fracture side; stainless steel implant) on the other hand.…”