Introduction: Since the introduction of joint arthroplasty major advances including the introduction of laminar airflow, have been made in reducing infection to current rates of 1 to 2%. Nonetheless infection remains a devastating complication, with major implications in terms of patient suffering, duration of hospital stay and financial burden. We undertook a study to examine the incidence of bacterial wound contamination occurring in the intra-operative period.

Materials and Methods: All patients admitted to our unit for elective hip and knee arthroplasty were entered into the study. On arrival in theatre a skin swab was taken. The patient was then prepared and draped in the anaesthetic room before final draping by the surgical team in the operating theatre. All procedures were performed in theatres equipped with laminar airflow, and all surgical personnel wore isolator suits. During the course of the procedure swabs were taken from the anterior aspect of the femur at 30-minute intervals. In addition the skin and inside blades and the suction tip were harvested at the end of the procedure. All samples were then sent for culture. Patient data including age, comorbid conditions and history of previous surgery were noted on a standardised pro forma. In addition, operative data including duration of the procedure, operating surgeon and type of drape and skin preparation used were noted.

Results: 65 patients have been examined to date. An incidence of contamination of 14% has been noted (9 patients) with the skin blade and suction tip being the most common source of contaminating organisms. Staphylococcus epidermis was cultured in 5 cases, with Gram negative organisms being cultured in the remaining samples. In all 9 cases only small numbers of organisms were identified. None of the patients with positive cultures developed clinical signs of deep or superficial wound sepsis, and all had an uncomplicated postoperative course.

Conclusions: While low levels of contamination are unavoidable in theatre, it is important that strict discipline be maintained in order to minimise this risk. In particular, careful attention to patient skin preparation, the use of prophylactic antibiotics and minimising use of the suction tubing help decrease contamination rates.

This study examines patient characteristics, indications for conversion, surgical and anaesthetic technique, peri-operative management and complications of surgery in this small and challenging group of patients. In the six years from 1994 to 1999, 33 conversion arthroplasties were performed for failed femoral hemiarthroplasty. The average age at conversion surgery was 75.5 years (range 65–90). The female to male ratio was 6:1. Primary hemiarthroplasties comprised 24 Austin-Moore, 6 Thompson & 3 Bipolar prostheses. The average interval from primary to conversion surgery was 50 months (6 months to 17 years). The average age at primary surgery was 71.2 years (62–88) – AMP:71.4 years, Thompson’s: 74.2 years, Bipolar: 63.5 years. All hemiarthroplasties were performed for fractured femoral necks. 62% of patients came from the Eastern Health Board area, while 38% were tertiary are referrals from other Health Boards. The average length of stay was 17.5 days (3–24). Indications for conversion included gross loosening/acetabular erosion in 9 cases, suspected infection in 4 cases and abscess/septicaemia in 1 case. All but 3 patients had significant pain (night pain etc.) and/or severely impaired mobility.

We also looked at anaesthetic and analgesic practice, surgical technique and prostheses used.

Post-operatively, mean total blood loss was 1430 ml (420–2280) with an average of 1.4 units of blood transfused (0–5). Intraoperative complications included acetabular & femoral perforation, periprosthetic fracture and cement reactions. Complications post-op (in hospital) included cardiac arrhythmia’s, cerebrovascular accidents, pulmonary embolus, myocardial infarct, respiratory & urinary tract infections, constipation, nausea & vomiting.

The elderly nature of these patients and the physiological stress of what is major surgery allied with multiple co-morbidities make their care especially challenging. A conversion arthroplasty is a procedure with a significant risk of considerable morbidity. Primary total hip replacement or bipolar hemiarthroplasty are options which, therefore, should be seriously considered in the case of fractured femoral necks to minimise the need for further surgery in the future, with all its attendant risks.

The longevity of total joint arthroplasty relies on articulating surfaces that are durable and produce little polyethylene debris and consequent osteolysis and loosening. In an effort to improve wear characteristics of the acetabular line, Hylamer (Du Pont Depuy Orthopaedics, Warsaw, Indiana) was produced as an alternative to ultra high molecular weight polyethylene. To date however reports using Hylamer with Cobalt chrome, stainless steel and alumina ceramic femoral heads have yielded results that have not reached the potential of initial in vitro trials. No study has examined the outcome following a Zirconia femoral head and a Hylamer acetabular shell. The tribological properties of Zirconia make it an ideal countersurface with low friction and long term durability. This study examines the outcome when these components were used in combination with a select cohort of patients and evaluates the benefit of their continued use.

From 1994 to 1997 fifty one patients had Hylamer cup with zirconia femoral head elite total joint arthroplasty performed. Forty-seven patients with fifty-eight arthroplasties were included in this study. All patients were less that fifty years with a male preponderance. There were eleven bilateral arthroplasties all of which had the second procedure at least two months from the index procedure. The principle diagnosis was osteoarthritis in forty-three hips with rheumatoid disease in twelve hips. The remaining two patients were operated on for end stage osteonecrosis.

The Elite total joint arthroplasty (DePuy, Warsaw in.) was used in all cases. The 22.225mm zirconia head was used exclusive in this study. The Hylamer shell used was a solid polyethylene block with a minimum depth of 6mm. Both the acetabular and femoral component were cemented with Palacos polymethylmethacrelate (Howmedica, Rutherford NJ) using third generation cementing techniques.

Patients were evaluated both clinically and radiographically three months and six months following surgery and thereafter at yearly intervals. Both the SF36 questionnaire and Mayo score were used to evaluate subjectively and objectively patient outcome. Regression analysis was used to determine if the age, sex and weight of the patient as well as the angle of inclination of the acetabular cup correlated with polyethylene wear and outcome. Kaplan Meir survival analysis was used to calculate the probability of survival of the original prosthesis.

There was no correlation between age, weight nor sex of the patient and outcome. The angle of inclination was correlated with a poorer ourcome but this did not reach statistical significance. The mean linear wear rate was 0.021mm year (range 0.011–0.055). Ten year survivalship analysis was calculated at 97%. SF 36 scores were standardised and the mean post operative score was 89 (range 62–97).

The results presented are significantly better than previously described in clinical trials using Hylamer liners. The reasons for this are multifactorial. This study used 22.225 mm heads in association with a solid cemented polyethylene acetabular block. Both have been associated with lower volumetric wear but neither have been used on previous studies of Hylamer. In addition the tribological properties of Hylamer may have been undermined in previous studies by poorly conforming countersurfaces using a different manufacturer for femoral and acetabular components. Finally the use of a second generation ceramic, zirconia with a Hylamer liner has produced medium term outcomes that confound previous reports and that exceed many published reports on traditional polyethylene liners.