Fixation augmentation using calcium-phosphate bone substitute improves outcomes of complex tibial plateau fractures. A matched, cohort study.

Introduction: Injectable cements have been developed to improve fixation's stability and thus obtain early return to adequate joint function. We aimed to compare post-operative radiographic and clinical outcomes of patients suffering from a complex tibial plateau fracture (TPF) fixed with calcium-phosphate bone substitutes (CPBS) augmentation to a matched group of patients with identical fracture pattern, treated with the same fixation's type, but augmented with bone grafting.

Methods: After local ethic committee approval, we retrospectively identified in a prospectively collected database, patients with complex comminuted metaphyseal and epiphysial bicondylar TPF (Schatzker type VI) admitted in our emergency department between January 2011 and December 2013. From those, 23 patients (14 males, 9 females) were treated with CPBS (Quickset-CP®, Graftys, Aix-en-Provence, France) fixation augmentation. Patients' mean age were 44.4 years. We then created a control group using a 1:1 matching process on gender, age, fracture pattern, and method of fixation. Patients were evaluated prospectively at 3, 6, and then every six  months using radiographic (AP/ML views) and clinical criteria (knee osteoarthritis outcomes score (KOOS) and EuroQOL-5D).

Results: Articular step-off and variation of articular step-off were significantly lower in the CPBS groups (mean step-off 1.4 ± 1.9 (0.5-6.5 mm) and mean step-off Δ = 0.3 ± 0.4 (0.5-2.2 mm)) than in the control group (mean step-off 3.6 ± 2.1 (1-7.5 mm) and mean step-off Δ = 2.2 ± 2 (0.5-7 mm) p < 0.01). At last follow-up, patients of the control group presented a higher rate of step-off > 2 mm and step-off Δ > 2 mm (respectively, 56 and 35%) than patients of the CPBS group (26 and 9%). Odd ratio of, respectively, 3.6 (95% CI (1.08-12.7) and p = 0.03) and 5.6 (95% CI (1.04-30.1) and p = 0.03).At mean follow-up of 29 months, KOOS pain subscore was significantly better in patients of the CPBS group (85.3 ± 12.1) than in control patients (74.2 ± 10.4 and p = 0.03).

Conclusion: The present study demonstrates that calcium-phosphate bone substitute used as synthesis augmentation improves mid-term radiological outcomes of patients suffering from complex tibial plateau fracture. Series reporting outcomes from a larger number of patients and longer follow-up must confirm clinical benefits and safety of this method.