Factors influencing the intrusion of methylmethacrylate into human tibiae

Three commonly used bone cements were inserted into tibiae from human cadavers to investigate techniques for optimal intrusion with manual pressurization. In each tibia the medial plateau was cleansed by pulsating water lavage, and the lateral plateau was cleansed by syringe only. Acrylic was inserted at one-minute intervals through four minutes, at which time intrusion decreased steeply. Intrusion was superior in bone prepared by pulsating lavage. Mixing the acrylic for no longer than three minutes prior to insertion by manual pressurization into bone prepared by pulsating lavage is suggested. Clinical use of this technique has improved intrusion, as evidenced by postoperative roentgenograms. As compared with interfacial strengths and depth of intrusion as reported in the literature, the penetration achieved with this technique gives an optimal depth of intrusion (2-4 mm) for adequate strength of the bone-cement composite. A new photographic computer technique is introduced for study of the intrusion of methylmethacrylate into bone. Differences in bone density can be accounted for by this technique, and the correlation coefficient to direct bone biopsy is 0.92.