Osteonecrosis with the use of polymethylmethacrylate cement for hip replacement: thermal-induced damage evidenced in vivo by decreased osteocyte viability.

Thermal damage to host bone is a possible source of compromise of fixation in patients undergoing cemented total hip replacement (THR). Data on the subject to date are derived from mathematical modelling powered by animal studies. The aim of this study was to assess the effect of cement thickness on osteocyte viability in a population of patients undergoing cemented THR. An in vivo model was designed and validated by means of a finite element analysis. During standard hip joint replacement in 14 patients, the femoral necks were exposed before final resection to the heat of a curing cement mantle equivalent to 2.5 (Group 1) or 5 mm (Group 2) in vivo in the cemented acetabulum. Matched controls were collected for each patient. Osteocyte counts and viability were assessed by means of haematoxylin and eosin (H&E) stain and lactate dehydrogenase (LDH) assay. Ex vivo experiments were performed to determine the extent of thermal insult. H&E staining proved unreliable for assessing thermal insult in the short term. The LDH assay was reliable and demonstrated a significant reduction in osteocyte viability to a depth of 2.19 mm in group 1 and 9.19 mm in group 2. There was a significant difference between the groups at all depths. The ex vivo experiments revealed thermoclines indicating that host bone in the population undergoing cemented THR is more sensitive to the thermal insult delivered by curing polymethylmethacrylate cement than previously believed. This thermal insult may weaken the fixation between bone and cement and contribute towards aseptic loosening, the commonest cause of failure of THRs.

Salvage of a failed Sauve-Kapandji procedure using a total distal radio-ulnar joint replacement.

This is the first report in the literature of a patient treated with a DRUJ replacement after Sauvé-Kapandji procedure failed due to pain and instability. The DRUJ replacement is an unconstrained, biomechanically more advantageous implant which can confer stability in cases where soft tissues are inadequate. We describe the treatment and outcome of persistent ulnar instability with a distal radio-ulnar joint replacement following failed salvage procedures for a malunion of a distal radius fracture.

Publication rates for hip surgery-related abstracts presented at national and international meetings.

Presentation at national and international meetings is a useful way to disseminate new information. Publication in a peer-reviewed journal remains the gold standard. We analyzed the publication rates of oral presentations from the British and European Hip Society, British Orthopaedic Association, and European Federation of Orthopaedics and Traumatology between 2003 and 2006. Multiple databases were used to identify publication of work presented as an abstract at these meetings. The publishing journal, time until publication, impact factor of publishing journal, and rate of publication identified by each database were analyzed. The overall mean publication rate across the 4 meetings was 23.4%; there were no significant differences between the meetings. Google Scholar (P<.01) and Medline (P<.05) identified significantly more publications than EMBASE. There were no significant differences between the mean impact factors of the publishing journals (P=.18). There were no significant differences in abstract publication rate or impact factor between meetings. The overall mean subsequent publication rates for presented abstracts related to hip surgery were low, and data presented but not yet published should be treated with caution. Google Scholar and Medline are superior to EMBASE for identification of peer-reviewed research.

Large diameter femoral head uncemented total hip replacement to treat fractured neck of femur.

The aim of this study was to investigate the use of large diameter head THR to treat fractured neck of femur, and to demonstrate if this conferred greater stability. Forty-six independent, mentally alert patients with displaced intracapsular fractures underwent THR. Mean age was 72.1 years. Outcome measures were dislocation, reoperation/revision rate, Oxford hip score (OHS), EuroQol (EQ-5D) and residential status. At mean follow-up (13.5 months) there were no dislocations. Reoperation, revision and infection rate were all 0%. Two patients died (4.3%). Mean pre-injury and postoperative OHS were 12.1 and 17.6, respectively. Mean pre-injury and postoperative EQ-5D index scores were 0.97 and 0.83, respectively. Mean postoperative walking distance was 2.5miles. There were no changes in residential status. This is the first published series using 36-mm diameter metal-on-metal THR for the treatment of fractured neck of femur. We have demonstrated that it affords patients excellent stability with no recorded dislocations.

Management of blood loss in periacetabular osteotomy.

The aim of this study was to determine the efficacy and cost-effectiveness of the use of predonation of autologous blood for the periacetabular osteotomy. We carried out a retrospective single surgeon series study looking at patient demographics, intraoperative blood loss, volume of red cells returned (by cell salvage and allogenic/autologous transfusion), and comparing pre- and postoperative haemoglobin levels in those that predonated and those that did not. One hundred and twenty-two procedures were performed on 107 patients between 1996 and 2005. An initial audit (22 procedures) revealed high wastage (45% returned) of allogenic blood. A predonation protocol was initiated and subsequently 100 procedures in 91 patients were performed. In 82 procedures, the patients were eligible for predonation. A total of 226 units of autologous blood were predonated and 92% was used. Only 13 of these patients (16%) required additional allogenic transfusion for unforeseen excessive blood loss intraoperatively. A set protocol for predonation reduces the need for allogenic transfusion and involves minimal wastage. In a procedure which has significant blood loss, we suggest that preoperative autologous donation is a safe and cost effective method of managing blood loss.