Abstract
Introduction Considerable advances have been made in improving cementing techniques in total hip replacement. Recently, the increasing need to minimize healthcare costs has led to the development of methods to reduce surgical time. It has been proposed that the curing time for bone cement can be markedly reduced by preheating the femoral component before insertion. A reduction of the period between insertion of the implant and ultimate curing decreases operative time, bleeding into the bone-cement interface and the likelihood of accidental loss of position. In a previous in-vitro study, preheating the femoral component to a temperature of about 50° resulted in a reduction in the bone cement curing time of approximately 50%. No adverse changes of the mechanical properties of cement were found. E-modulus, fracture toughness and fatigue strength were unaffected by increased temperature. A uniform trend of decreasing porosity of bone cement with increased temperature of the implant was also observed. To-date, there have been no reports on the in-vivo outcome of the preheating cementing technique. The aim of this prospective study was to assess the clinical and radiological five year follow-up results of the preheating cementing technique used for the fixation of the femoral stem (Lubinus, Link, Germany).
Methods One hundred consecutive patients (100 hips) with osteoarthritis and an average age of 72 years (range 65 to 85) have been operated on by one surgeon in a single institution. In a cohort of 50 hips a conventional cementing technique was used. The cement used was Cemex (Tecres, Italy). The anterior-posterior and lateral radiographs have been evaluated with a computer-aided system. The quality of cement mantle was assessed on the radiographs according to the A-B-C1-C2-D classification.
Results The curing time of the bone cement was markedly reduced (average five minutes, range four to seven minutes) by preheating the femoral component (40° to 50°). The estimated reduction of intra-operative blood loss was 75 ml (range 45 to 130). The mean Harris Hip Score was 94.8 points at follow-up (range 79 to 100). The clinical status of 92% of hips was rated good or excellent, eight percent was rated fair. A satisfactory cementing technique was obtained in 96% of hips. Small voids in the cement mantle (grade C1) were present in four percent of hips. Non-progressive radiolucent lines at the bone-cement interface were observed at Gruen zone one in four hips, at zone eight in three hips and at zone 14 in three hips. No signs of osteolysis were observed at follow-up, all stems were rated radiologically stable.
Conclusion A reduction in curing time of bone cement provides a significant time saving without compromising implant performance. We recommend preheating of femoral components to surgeons experienced in joint replacement and have a skilled surgical team, because of the potential risk of premature polymerization before complete seating of the implant.
In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.
The abstracts were prepared by Mr Jerzy Sikorski. Correspondence should be addressed to him at the Australian Orthopaedic Association, Ground Floor, William Bland Centre, 229 Macquarie Street, Sydney NSW 2000, Australia.
