Aims: To determine the usefulness of preoperative CRP, ESR, WCC and joint aspirate in the diagnosis of infective loosening before revision TKA.

Methods and Materials: Retrospective review of patients undergoing revision TKA for the period May 1998 to May 2008 was performed, examining the results of preoperative CRP, ESR, WCC, joint aspirate and intra-operative microbiological samples. Positive results were CRP ≥10 mg/dL, ESR ≥ 22mm/hr, WCC ≥11 g/dL and positive growth on culture unless stated as contaminant. The data was analysed to determine sensitivity, specificity, negative and positive predictive values of the tests for single stage and staged revisions.

Results: 51 patients underwent single stage revision with 10 positive cultures. CRP and WCC were highly specific for infection (84%, 98%) with low sensitivities (10%). ESR was 66% specific and 25% sensitive. All had high negative predictive values (76–86%).

23 patients underwent staged revision. 17 cases had positive cultures at 1st stage and 8 at 2nd stage. 1st stage CRP, ESR and WCC had low sensitivity (67%, 59%, 17%). WCC was 80% specific whereas CRP and ESR had low specificity (25%, 20%). All had high positive predictive value (71–80%). 2nd stage CRP and ESR were specific for infection (71%) but had low sensitivities (22 and 44%). WCC was 0% sensitive but 87% specific. Negative predictive values of CRP, ESR and WCC were 63, 71 and 62%.

For both single stage and 1st stage staged revisions, pre-operative joint aspirate was 100% specific with sensitivities of 0% for single stage and 50% in staged revisions.

Conclusion: All patients undergoing both staged and single stage revision arthroplasty should routinely have preoperative inflammatory markers and joint aspirate. However, positive intraoperative cultures may still be obtained despite negative preoperative investigations.

Aims: To determine the rate of early and late infection amongst patients with renal disease undergoing TKA.

Methods and Materials: Review was undertaken of the Scottish National Arthroplasty Project data for the period from April 1985 to March 2008. Data was examined for the rate of infection amongst patients under-going TKA with a diagnosis of renal transplant, renal dialysis or renal failure. Early infection was classed as occurring within 90 days of the index procedure and late infection as occurring after 90 days. Renal failure, dialysis and transplant were identified using ICD 9 and 10 codes. The 4th revision of the OPCS codes was used to search for renal transplant, renal dialysis and knee arthroplasty.

Results: In total, 59288 TKAs were performed in Scotland over the period analysed. There were 651 early infections and 1296 late infections giving overall early and late infection rates of 1.1% and 2.2% respectively. 10 patients had renal transplant prior to TKA with 1 early infection (infection rate 1%) and no late infections. 44 patients had a renal transplant before or after TKA with 1 early and 6 late infections giving an early infection rate of 2.27% and late infection rate of 13.64% for this group. 17 patients undergoing renal dialysis underwent TKA with no early infections but a single late infection, giving a late infection rate of 5.8%. 2920 patients had a diagnosis of renal failure prior to or after TKA with 48 early and 138 late infections. Infection rates for this group were 1.64% early and 4.73% late.

Conclusions: TKA patients with renal transplant, renal failure or undergoing dialysis are at increased risk of infection. In particular, renal transplant patients are most at risk of late infection. Renal patients must be counselled of these increased risks prior to orthopaedic or transplant surgery.

The aim of this work was to compare the oxygen saturations in patients in the early period following total knee joint replacement surgery performed using either computer navigation or conventional intramedullary mechanical jigs.

Between August and November 2007 twelve consecutive patients who had computer navigated total knee joint replacements were prospectively reviewed. A comparison group from the same period was made of twenty patients who had knee replacements performed with conventional jigs in this same period. Non-invasive oxygen saturations were measured and recorded as a percentage. Preoperative oxygen saturations measured at the assessment clinic were used a baseline. For the duration of the patients postoperative hospital stay oxygen saturations were measured five times a day as well as their oxygen requirements.

We found that the patients in the computer navigation group on average reached oxygen saturation levels on air equal to those measured in the assessment earlier than the intramedullary jig group (2.2 days versus 2.8 days). There was also a lower need for oxygen and shorter length of stay in the computer navigated group during this early post operative period (4.6 versus 6.0 days).

Previous studies using transcranial Doppler and transoesophageal echocardiograms have shown a reduction of systemic emboli with computer navigated total knee joint replacements. Using oxygen saturation monitoring we have shown there may be a considerable clinical advantage using computer navigated surgery over conventional intramedullary jigs in knee replacement surgery.

The aim of this work was to compare the oxygen saturations in patients in the early period following total knee joint replacement surgery performed using either computer navigation or conventional intramedullary mechanical jigs.

Between August and November 2007 twelve consecutive patients who had computer navigated total knee joint replacements were prospectively reviewed. A comparison group from the same period was made of twenty patients who had knee replacements performed using conventional jigs. Non-invasive oxygen saturations were measured and recorded as a percentage. Preoperative oxygen saturations measured at the assessment clinic were used a baseline. For the duration of the patients postoperative hospital stay oxygen saturations were measured five times a day as well as their oxygen requirements.

We found that the patients in the computer navigation group on average reached oxygen saturation levels on air equal to those measured in the assessment earlier than the intramedullary jig group. There was also a lower need for oxygen in the computer navigated group during this early post operative period.

Previous studies using transcranial Doppler and transoesophageal echocardiograms have shown a reduction of systemic emboli with computer navigated total knee joint replacements. Using oxygen saturation monitoring we have shown there may be a considerable clinical advantage using computer navigated surgery over conventional intra-medullary rod jigs in knee replacement surgery.

Introduction: We hypothesised that a stemmed hybrid total hip replacement with a large metal head, (LMOM), with the same bearing technology, would give early functional results as good as hip resurfacing (HR) with fewer contraindications and reduced morbidity due to a less invasive approach.

Methods: We performed a 12 month observational study of consecutive patients undergoing LMOM (n=40) and HR (n=60). Patients’ age, sex, blood loss, hospital stay and early complications were compared as well as pre and post-op Oxford scores and range of movement.

Results: The HR group was younger with more normal hip morphology. Mean age 54years HR/ 59years LMOM, BMI 28 and 29 respectively. Diagnosis of primary osteoarthritis 77% HR compared to 47% in LMOM group. Operation time, blood loss and haemoglobin drop were similar in both groups. The LMOM group achieved an earlier discharge of 5.5 days compared to 6.3 (p< 0.12). Complications included 2 aseptic wound leakages in the LMOM group. In the HR group an aseptic wound leakage, superficial infection and a sciatic nerve palsy was observed. At 6 week and 3 month follow up, the range of moment of both groups was very similar. Mean Oxford hip scores were 44 preoperatively and 22 postoperatively in the HR group and 45 falling to 24 in the LMOM group.

Discussion: LMOM compared to HR is preferable in respect to hospital stay and reduced perioperative complications despite an older cohort with a wider variety of arthritic pathologies. However longer follow up is required to conclude further.