A model for evaluating the biomechanics of rib fracture fixation.

INTRODUCTION: High rates of morbidity and mortality following flail chest rib fractures are well publicized. Standard of care has been supportive mechanical ventilation, but serious complications have been reported. Internal rib fixation has shown improvements in pulmonary function, clinical outcomes, and decreased mortality. The goal of this study was to provide a model defining the biomechanical benefits of internal rib fixation. METHODS: One human cadaver was prepared with an actuator providing anteroposterior forces to the thorax and rib motion sensors to define interfragmentary motion. Cadaveric model was validated using a prior study which defined costovertebral motion to create a protocol using similar technology and procedure. Ribs 4-6 were fixed with motion sensors anteriorly, laterally and posteriorly. Motion was recorded with ribs intact before osteotomizing each rib anteriorly and laterally. Flail chest motion was record with fractures subsequently plated and analyzed. Motion was recorded in the sagittal, coronal and transverse axes. FINDINGS: Compared to the intact rib model, the flail chest model demonstrated an 11.3 times increase in sagittal plane motion, which was reduced to 2.1 times the intact model with rib plating. Coronal and sagittal plane models also saw increases of 9.7 and 5.1 times, respectively, with regards to flail chest motion. Both were reduced to 1.2 times the intact model after rib plating. INTERPRETATION: This study allows quantification of altered ribcage biomechanics after flail chest injuries and suggests rib plating is useful in restoring biomechanics as well as contributing to improving pulmonary function and clinical outcomes.

Sternotomy closure using rigid plate fixation: a paradigm shift from wire cerclage.

BACKGROUND: Rigid plate fixation (RPF) is the cornerstone in managing fractures and osteotomies except for sternotomy, where most cardiac surgeons continue to use wire cerclage (WC). Results of a multicenter randomized trial evaluating sternal healing, sternal complications, patient reported outcome measures (PROMs), and costs after sternotomy closure with RPF or WC are summarized here. METHODS: Twelve US centers randomized 236 patients to either RPF (n=116) or WC (n=120). The primary endpoint, sternal healing at 6 months, was evaluated by a core laboratory using computed tomography and a validated 6-point scale (greater scores represent greater healing). Secondary endpoints assessed through 6 months included sternal complications and PROMs. Costs from the time of sternal closure through 90 days and 6 months were analyzed by a health economic core laboratory. RESULTS: RPF compared to WC resulted in better sternal healing scores at 3 (2.6±1.1 vs. 1.8±1.0; P<0.0001) and 6 months (3.8±1.0 vs. 3.3±1.1; P=0.0007) and higher sternal union rates at 3 [41% (42/103) vs. 16% (16/102); P<0.0001] and 6 months [80% (81/101) vs. 67% (67/100); P=0.03]. There were fewer sternal complications with RPF through 6 months [0% (0/116) vs. 5% (6/120); P=0.03] and a trend towards fewer sternal wound infections [0% (0/116) vs. 4.2% (5/120); P=0.06]. All PROMs including sternal pain, upper extremity function (UEF), and quality-of-life scores were numerically better in RPF patients compared to WC patients at all follow-up time points. Although RPF was associated with a trend toward higher index hospitalization costs, a trend towards lower follow-up costs resulted in total costs that were $1,888 less at 90 days in RPF patients compared to WC patients (95% CI: -$8,889 to $4,273; P=0.52) and $1,646 less at 6 months (95% CI: -$9,127 to $4,706; P=0.61). CONCLUSIONS: Sternotomy closure with RPF resulted in significantly better sternal healing, fewer sternal complications, improved PROMs and was cost neutral through 90 days and 6 months compared to WC.