The effect of cement restrictors on the occlusion of the humeral canal - An in vitro comparative study of 2 devices

An in vitro study investigated the efficacy of cement restrictor devices on cement containment and penetration within the humerus. Eight pairs of pres erved humeri were prepared using advanced cementing technique followed by i nsertion of 1 of 2 cement restrictors. Low-viscosity cement was injected fo llowed by sham humeral stem insertion. Each specimen was sectioned into tra nsverse 10-mm slices. slices were photographed and digitized to quantify th e cement/stem and canal cross-sectional area. Cement penetration was determ ined from the ratio of cement area to canal area. A significant increase in cement penetration was observed among slices from distal to proximal for b oth restrictors (P =.02). There was no significant difference in cement pen etration, leakage, or migration between restrictors. Five of the 8 specimen s migrated, with means of 21.5 +/- 25.0 mm and 24.0 +/- 36.0 mm for the pol yethylene and silicone restrictors. Leakage or migration resulted in a sign ificant decrease in cement penetration with the polyethylene restrictors (P =.001). In the silicone restrictor group, migration resulted in decreased cement penetration (P =.04). When using advanced cementing techniques, intr amedullary restrictors allow improved cement penetration; however, they do not ensure cement containment.