Superior compressive strength of a calcaneal fracture construct augmented with remodelable cancellous bone cement

Twenty-six paired, fresh-frozen cadaveric feet were disarticulated at the a nkle joint, and the dome of the talus was potted. Stress-risers were placed along the medial, lateral, and posterior aspects of the calcaneus, and the specimen was loaded rapidly to failure in a testing machine: to produce a type-IIB displaced intra-articular fracture according to the classification system of Sanders et al. One specimen of each pair was treated with standa rd internal fixation with bone-grafting (the control group), and the other was treated with similar fixation but with SRS (Skeletal Repair System) cal cium phosphate bone cement placed in any osseous defect. All of the specime ns were cured for twenty-four hours in a bath of saline solution at 37 degr ees Celsius. The specimens were tested cyclically for ten cycles from zero to 100 newtons at one hertz and for 1010 cycles from zero to 350 newtons at one hertz. The deformation per cycle (millimeters per cycle), first-cycle deformation (millimeters), number of cycles to failure, and number of speci mens withstanding the cyclical testing were calculated. The specimens were examined radiographically before and after fracture and after reconstructio n and testing. A large difference in the results of the cyclical testing was noted. The sp ecimens that had been augmented with the SRS bone cement had an average def ormation of 0.00195 millimeter per cycle compared with 1.013 millimeters pe r cycle in the control group (p < 0.005). A similar magnitude of difference was noted when the results were stratified for good and poor-quality bone. Visual examination and radiographs demonstrated that a type-IIB displaced intra-articular fracture had been created reproducibly, and computed tomogr aphic scans showed that nearly anatomical reconstruction had been achieved in all of the specimens. The computerized tomographic scans revealed good f illing of the osseous voids and no evidence of failure of the cement after cyclical loading. CLINICAL RELEVANCE: We noted a large increase in the stability and compress ive strength of the fixation of the calcaneal fracture constructs that had been augmented with the SRS bone cement. Clinical use of this new bone ceme nt could considerably increase the initial strength of the fracture constru ct, which could lead to more rapid rehabilitation after this difficult frac ture. In addition, the bone cement may obviate the need for autogenous bone -grafting.