The metabolic response of trauma may mimic infection and the reliability of serological parameters for diagnosing infection may be questionable. We prospectively assessed the changes in the acute inflammatory markers, febrile response and the immune profiles of 101 patients following primary hip arthroplasty and their association with infection. Method: The clinical outcome of 101 patients was monitored. Serological analysis was performed pre-operatively and on the second and 8th post-operative day as well as in an out patient clinic 6 weeks following surgery. The serological markers included total white blood cell count along with T and B lymphocyte function. Levels of CD4, CD8 and CD56 were analysed for T helper, T Cytotoxic cell and Natural Killer cell activity. Inflammatory makers included plasma viscosity and CRP. Serological titres of Staph. Aureus and Staph. Epidermis were performed preoperatively and on day 8 and week 6 following surgery. Results: post-operative complications included 19 UTI, 11 chest infections and three URTI and six a confirmed deep vein thrombosis. Twenty patients had elevated ASO titres and 19 patients had raised Staph. Epidermis titres. Statistical comparison of WBC, Plasma viscosity, temperature profiles and T helper, T cytotoxic cell and NK cell assays is not different between patients with and without systemic infection or raised titres of Staph. Aureus or Staph. Epidermis. Conclusion: The acute phase responses following surgery and metabolic response to trauma obscures the changes seen in infective complications up to six weeks post-operatively. Their use in diagnosing infection appears unjustified.

It has been proposed that scoring systems could be nationally used, initially on a secondary care level as a method of prioritising patients on waiting lists for hip and knee arthroplasty. If this were to be successful, scoring systems could be used as a way of tackling the ever increasing waiting list times for surgery which currently stand at around 15 months on the NHS.

I studied and compared the New Zealand and Oxford Hip and Knee Scores, collecting data from 79 patients over a period of seven weeks.

I found that generally, patients who scored highly were recommended for surgery; however I also found that in the group of patients recommended for surgery there was a wide range of scores obtained. There was also a great deal of overlap between the scores obtained by those who were recommended for surgery and those who were not. This means that it would be very difficult to predict a decision for an individual patient based purely on their scores. In addition, many confounding variables can affect the wide range of scores obtained.

I concluded that there was too much variation between the scores obtained by patients undergoing surgery to be able to consistently and fairly prioritise them. In order to implement the use of scoring systems in this country, nationally approved criteria and priority banding categories need to be established. Scoring systems need to be modified to be clearer and to cover more variables. Larger studies need to be conducted with more patients and over a longer period of time; and further work could be done into the proposal that GP’s could use these systems as a tool for referral to consultant out-patient clinics.

Purpose: The purpose of this study was to assess preoperative bone stock and immediate postoperative cement-bone interface as factors affecting infection control and mechanical outcome after one stage revision total hip replacement (THR) for deep infection.

Material and methods: This study included 115 cases which satisfied following conditions; a) One stage revision THRs for deep infection were carried out by a single surgeon (BMW). b) Follow-up of more than five years was possible. c) Complete series of radiographs were available including preoperative, immediate postoperative and the latest follow-up ones. Preoperative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localized cavitation, Grade 3: Significant bone loss). Immediate postoperative cement-bone interface was also graded into four categories (Grade A: White-out, obscure interface, Grade B: Clear line, no measurable gap, Grade C: Gap> 1mm, Grade D< 1mm). These two factors were analysed in view of infection control and mechanical survival of implants after surgery.

Results: Preoperative bone stock did not show significant influence on infection control while it affected mechanical outcome. Immediate postoperative cement-bone interface was an affecting factor for not only mechanical survival of implants but cure of infection.

Conclusion: Preoperative bone stock and immediate postoperative cement-bone interface were assessed as influential factors in one stage revision THR for deep infection. There was a good chance of cure of infection even in cases with significant bone loss. Good cement fixation appeared to be important in view of infection control as well as mechanical survival of implants.

Pyrexia in the post-operative setting has often been associated with a possible systemic or wound infection. We assessed whether there is any justification for our concern regarding post-operative pyrexia following hip arthroplasty and subsequent deep prosthetic infection.

We undertook an assessment of the clinical outcome of 97 sequential patients who underwent 103 primary hip arthroplasty for primary osteoarthritis replacements. Daily temperature and systemic complications in the post-operative period were recorded. Clinical outcome was measured using an Oxford hip questionnaire.

Patients had a mean follow-up of 5.2 years (range 3.5–7.2years)

We reviewed the postoperative temperature records of 80 patients who had undergone primary total hip replacement. Thirty-one patients had required revision surgery at a mean time interval of 37.2 months (range 5–74 months) for confirmed deep prosthetic infection. The remaining Forty-nine patients were asymptomatic at a mean follow-up of 31.5 months.

Study 1

Post-operative pyrexia of 38 degrees Celsius was present in 51% of patients undergoing primary hip replacement in the first post-operative week but in 21.1% no etiological cause could be identified. Clinical outcome measured by an Oxford hip questionnaire was not influenced by the post-operative temperature pattern.

Study 2

The mean peak temperature on the first post-operative day was significantly lower in patients with deep prosthetic infection then patients with a clinically normal outcome (p=0.01).

Post-operative pyrexia is clearly not uncommon following primary arthroplasty and its presence should not be regarded as detrimental. Pyrexia in the postoperative setting is a component of the acute phase response to trauma and study 2 demonstrates patients who develop a low-grade infection following arthroplasty may have a diminished febrile response to surgical trauma which may be an indirect representation of a diminished immune response to surgical trauma or infection

Deep infection is one of the most serious complications after total hip replacement (THR). The aim of this study is to evaluate the efficacy of one stage revision THR for deep infection with a long-term follow-up.

One stage revision THR for deep infection was carried out in 285 joints on 274 patients by a single surgeon (BMW) between 1974 and 2001. All infected hip replacements are primarily treated with one stage revision THR at the authors’ unit unless bone stock is extremely poor. This study included a review of 162 revisions in 154 for which a minimum follow-up of five years had been done. The mean duration of follow-up was 12.3 years.

Trochanteric osteotomy was done for extensive resection of infected tissue and removal of cement. Both cups and stems were revised with bone cement. Antibiotic-loaded cement was used in 152 cases (93.8%). Further antibiotics were commenced systemically for 6–12 weeks postoperatively.

Failure of infection control was defined as a) reoperation for recurrent infection or b) clinically persistent infection. Infection control. One hundred and thirty eight hips (85.2%) were free of infection at the time of the latest follow-up. 1) No sinus group (N=110): Success rate was 82.7 %. 2) Sinus group (N=52): Success rate was 90.4 %.

This study presents the longest follow-up with a large number of cases in revision THR for deep infection. At least, history of discharging sinus was not considered as a contraindication. The results suggested that one stage revision was an effective treatment for deep infection of hip replacement in the long term.

We retrospectively analysed three hundred and one infected total hip replacements. Infection was defined on the basis of the surgeons clinical impression. This included a thorough history and physical examination, laboratory and radiographic evaluation. Peri operative findings were also taken into consideration.

Despite the overt appearances of sepsis fifty seven of these three hundred and one cases demonstrated no bacterial growth. These were excluded from the microbiological analysis.

The remaining two hundred and forty four cases oven bacteriological evidence of deep infection. Thirty seven cases grew two different organisms both of which were felt to be clinically significant. The remainder grew a single organism. Hence a total two hundred and eighty one bacteriological isolates were grown.

Coagulase negative staphylococcus accounted for 54.8%, staphylococcus aureus 13.5%, streptococci 8.9%, Escherichia coli 6.1% and diptheroids 2.5%.These organisms were plated out in a standard fashion against a variety of antimicrobial agents.

We analysed ten antibiotics and their sensitivity profiles against the spectrum of organisms demonstrated by this series.

Best antimicrobial coverage by a single antibiotic was afforded by fucidic acid (85.3%) and erythromycin (79.6%). Gentamicin was found to be sensitive to only 76.1% of the bacteria present at the time of revision for deep infection.

Combining gentamicin with other antibiotics improved the theoretical coverage. A combination of gentamicin and fucidic acid demonstrated a 97.5% coverage. Gentamicin with erythromycin gave 95.2%.

When treating the infected arthroplasty it may be beneficial to add extra antibiotics to bone cement. This may either be to the cement spacer in a two stage revision or to the definitive cement in a single stage revision. We would suggest that fucidic acid or erythromycin would be good candidates for this. These candidates should also be considered when designing the next generation of combination antibiotic acrylic bone cements.

Bacterial resistance in joint replacement surgery is an emerging problem. A review of the bacteriology from infected revisions performed at Wrightington over the past 5 years has shown that the most common organism is coagulase negative staphylococcus (59%), followed by staphylococcus aureus (17%).

The sensitivity profiles are shown below.

Gentamicin is the most commonly pre formulated antibiotic added to acrylic bone cement. The above data clearly demonstrates that for 32% of infected cases gentamicin alone is inadequate prophylaxis. As a consequence of this the use of additional antibiotics for resistant cases is becoming commonplace.

The aim of this study was to investigate the mechanical properties of additional antibiotics in acrylic bone cement.

The 7 antibiotics listed above were selected on the basis of sensitivity to organisms isolated at revision for deep infection. Each was added at a loading of 1g active to CMW1 RO (plain) and CMW1 G (gentamicin). The antibiotics were mixed with the polymer by hand. The cement was then mixed as per manufacturer’s instructions.

Dough and setting times were noted. Standard samples were produced using ISO approved moulds. Each antibiotic/cement combination was tested for compression strength, impact strength and flexural strength.

All antibiotic/cement combinations performed as well as the control mix when tested for compression and impact strength. The flexural strength results for fusidic acid and erythromycin when added to acrylic cement were comparable to the control mix. Flucloxacillin, clindamycin and teicoplanin did lower the flexural strength to just below acceptable limits. However Vancomycin when added at 1g active reduced the flexural strength of acrylic bone cement significantly.

Although vancomycin may remain one of the last bastions of antibiotic therapy our study suggests that’s its addition to acrylic bone cement significantly weakens its mechanical properties. We would advise caution in its use as this may reduce the chances of long term success when undertaking revision for deep infection.

Objective: To study the incidence of MRSA (Methicillin resistant Staphylococcus aureus) at pre-operative screening and relate this to positive cultures of the tissue in joint replacement surgery.

Setting: Elective joint replacement centre with routine MRSA screening facility.

Design: Retrospective review of MRSA screening and positive tissue samples taken during one year period from 1.11.99 to 31.10.00 in hip and knee replacements.

Results: Eighteen (18) out of the 2867(0.7%) screens performed on patients undergoing joint replacement surgery had MRSA isolated from one source or other. However, no MRSA was found from tissue samples taken during the surgery. But 63 isolates from 499 tissue samples (12.6%) were reported as coagulase negative staphylococcus, out of which 28(44%) were resistant to Methicillin.

After observing the incidence of Methicillin resistant coagulase negative staphylococcus during one year, we reviewed the tissue culture reports in revision hip replacements from May 1974 till July 1999. Two hundred ninety-one (291) positive organisms were isolated from 337 cultures, out of which 57.5% were coagulase negative staphylococcus 11.9% staphylococcus aureus. Methicillin resistance was noted in 30.8% of coagulase negative staphylococcus as opposed to 6% of staphylococcus aureus.

Conclusion: Staphylococcus epidermidis is the most prevalent and persistent species on human skin and mucous membranes, constituting 65–90% of all staphylococci (Mandell, Douglas & Bennett, 2000). Since a majority of isolation in tissue samples constitute methicillin resistant coagulase negative staphylococcus, would it be more appropriate to screen for Methicillin resistant Staphylococcus epidermidis (MRSE), rather than MRSA, in patients undergoing joint replacement surgery?

The aim of this randomised prospective study was to establish whether the use of knee splints following total knee replacement is necessary.

The study included 81 patients undergoing total knee replacement who were randomised into a ‘splint’ and a ‘no splint’ group postoperatively. Patients in the ‘splint’ group had their knee splinted in extension in the early post-operative period but the splint was removed for the patients to do exercise. Splintage was completely removed when the patient could straight leg raise. Patients in the ‘no splint’ group had a wool and crepe bandage applied around their knee and allowed to fully mobilise from the first postoperative day. The following parameters were recorded: The range of movement preoperatively, 5 days post-operatively and 6 weeks postoperatively; the length of time to straight leg raise; the blood drained from the wound. and the amount of postoperative analgesia required.

Using the unpaired 2 tailed t-test it was found that patients in the four ‘no splint’ group achieved significantly greater flexion at 5 days and 6 weeks post-operatively but drained significantly more blood from the wound. Transfusion requirements were similar in the two groups. There was no other significant difference in the parameters measured between the two groups.

In conclusion we found no evidence to advocate the use of knee splints following total knee arthroplasty.