Introduction: Scant amount of information is available on mechanical properties of composite specimens of old and new cement. In previous studies evaluating this, old samples were only few days old, unlike clinical situation, where the old cement is a few years old.

We evaluated short-term mechanical properties of composite specimens and compared these with new uniform specimens.

Material and Methods: Uniform and composite specimens were fabricated and were tested for bending, tensile and shear strength. Seventeen beams and eight cylindrical specimens fabricated earlier (median age 11.8 years) using same moulds were available to form composite specimens. Specimens were stored in saline at 37 °C for 6 weeks before testing.

Results: Bending tests: Load and bending stress for new specimen was 82.9N and 49.5MPa as compared with 74.3N and 40.3MPa for composite specimens. 4 composite specimens failed though old cement, 3 through junction and 1 through new cement. There was no statistical difference in maximum load (p, 0.3) or stress (P, 0.06) between uniform and composite specimens.

Tensile tests: Load and tensile stress for new specimen was 941.5N and 29.5MPa as compared with 726.9N and 22.1MPa. There was difference in the load and stress of uniform specimens as compared with composite specimens.

Shear tests: Load and shear stress for new specimen was 2692.9N and 34.5MPa as compared with 2009.9N and 25.3MPa. There was significant difference in load as well as stress in uniform specimens as compared with composite specimens.

Discussion: This study demonstrates that composite specimens fail at 89.6% of bending load, 77.2% of tensile and 74.6% of shear load as compared with uniform new cement specimens. Of more importance is the fact that only four of these composite specimens (23.5%) failed at the junction and the rest thirteen failed either through old cement (64.7%) or through new cement (11.8%).

Introduction: Pressurization of PMMA can lead to cement extrusion. Although rare, the complications related to cement extrusion (‘CE’) are serious such as neurological, urological and vascular injuries. In a recent study the incidence of CE from acetabulum was found to be 42–50%, most of which was under transverse ligament. We advocate a technique of applying cancellous autograft on the medial floor and under the transverse ligament to provide cancellous surface for cement pressurisation, and to prevent CE. The aim of this study was to review our incidence of CE and radiolucent lines (‘RLL’).

Methods: Study group included 380 consecutive patients undergoing primary implantation of flanged cemented cup with spacers during 2002–2003. The mean age was 68 years. Surgeons of all grades, including junior doctors under supervision, performed the procedure. Early postoperative radiographs were reviewed to identify the incidence, site and extent of CE and incidence of RLL.

Results: We identified CE in 46 radiographs, 35 being inferior, 6 pelvic and 5 along retractors. The mean size of the CE was 240.5 mm². Radiolucent lines (RLL) in any of the Charnley zone were present in 58 cases. Two zone RLL were seen in seven cases (1.8%) and a circumferential radiolucency in one case (0.3%). There was no significant correlation between the grade of the operating surgeon and the incidence of CE (p, 0.15). There was no significant correlation between the grade of operating surgeon and the presence of RLL (p, 0.18).

Discussion: Results of this study confirm that incidence of CE with this technique is significantly less as compared with historic data (12% vs. 42%). Incidence of RLL is also less especially in zone 2 and 3. These findings support our hypothesis that use of autograft to convert acetabulum in contained hemisphere reduces incidence of CE and improves pressurization.