Biomechanical Performance of 4-Leg Sustained Dynamic Compression Staples in First Tarsometatarsal Arthrodesis

BackgroundThis study investigates the biomechanical efficacy of new 4-leg Sustained Dynamic Compression (SDC) NiTiNOL staples, hypothesized to offer superior stability and resilience to loading before fusion completion, compared with conventional hardware.MethodsTwenty sawbones left full foot models were divided into 4 treatment groups: (1) 4-leg Inline Staple, (2) 4-leg Inline Staple + 2-leg Staple, (3) 4-leg Inline Staple + Screw, and (4) Plate + Screw. An osteotomy was performed to simulate a Lapidus procedure, and the respective fixation methods were applied. Mechanical testing was conducted using a servo-hydraulic testing machine to evaluate constructs' load, contact force, contact area, and plantar gap.ResultsThe 4-leg Inline Staple + Screw group demonstrated significantly increased joint contact force, joint contact area, and decreased plantar gap compared with the Plate + Screw group, both before and after cyclic testing. All SDC-containing constructs exhibited post-cyclic joint contact areas that were 2.36×, 3.87×, and 5.49× greater than the post-cyclic plate + screw group. Most notably, the 4-leg Inline Staple + Screw group maintained a plantar gap of less than 3 mm throughout the testing, unlike other groups.ConclusionsThe 4-leg Inline SDC Staple, particularly when combined with a static screw, demonstrated biomechanical superiority over traditional plate and screw constructs in Lapidus procedures. These findings suggest a promising avenue for enhanced post-operative stability, which could translate into quicker patient recovery, improved fusion rates, and potentially lower non-union rates. Further clinical trials are warranted to validate these biomechanical advantages in patient outcomes.Level of Evidence:Therapeutic, Level V: Bench Testing.