HIP International

One reason why otherwise well-functioning total hip replacements have a finite service life is eventual aseptic loosening of the implants because of osteolysis induced by wear particles from the artificial bearing. Pain and osteolysis from wear debris can manifest even in the absence of aseptic loosening. Total hip replacements with ceramic-on-ceramic articulations have shown less wear both in vitro and in vivo. A randomized prospective clinical trial was conducted to compare the outcomes of ceramic-on-ceramic articulations to ceramic-on-polyethylene articulations. Two-year data are of interest because premature failures of ceramic femoral heads usually occur by this time interval. Of 500 patients enrolled in this trial, half received total hip replacements with alumina-on-alumina bearings, while the other half had ceramic-on-polyethylene bearings. At the two-year follow-up, 444 patients (217 study group and 227 control group) were available for review. The clinical and radiographic outcomes between the groups were comparable, and reflected the typical results of primary total hip replacements. No complications related to spontaneous failures of the ceramic bearings were observed at this early follow-up period. Further follow-up is needed to confirm these findings over the long-term, but the short-term safety of alumina ceramic bearings in hip replacements reported in other recent reports is further validated by our findings.

We obtained postoperative blood concentrations of Co, Cr, Mo, Ti, Al and Nb in 75 patients undergoing primary THA at our institution between January 1998 and December 2000. All patients were treated with the same prosthetic device (Alloclassic^® VARIALL™, Zimmer, Winterthur, Switzerland) using three types of articulations: metal-on-metal (METASUL^™), ceramic-on-ceramic (CERASUL^™) and metal-on-cross linked polyethylene (DURASUL^™). 25 patients out of each articulation-group were evaluated by blood analysis 24–38 months after surgery. The patients were submitted to strict criteria of inclusion. Comparing the three articulation-groups there were no significant differences in the categories age, follow-up time and preoperative blood level of creatinine. The Al-, Ti- and Nb-blood levels were all below their detection limit. Regarding the median blood concentrations of Mo, we found no statistically significant differences comparing the three articulations (p>0.05). The median Co blood concentration in the ceramic group was 0.19 ng/mL, 0.69 ng/mL in the metal group and 0.19 ng/mL in the cross-linked PE group. The difference between the metal and ceramic group and between the metal and polyethylene group is statistically significant (p=0.001 in both comparisons). The median blood concentration of Cr was 0.19 ng/mL in the ceramic and in the cross-linked PE group, and 0.47 ng/mL in the metal group, the difference being statistically significant (p=0.003 and p=0.0002). Although the blood concentrations of Co and Cr were significantly higher in patients with a metal-on-metal articulation they were far from reaching toxic levels.

In order to reduce the final stages of cementing time and intra-operative time, we analysed the behaviour pattern of a quick-setting cement. Quick-setting cement permits easy and adequate manipulation, which reduces surgical time and also the technical problems caused by waiting for setting to be completed. In order to verify the efficacy of faster cement, a double-blind randomised study was carried out comparing a type of traditional cement with quick-setting cement. Two groups of 20 patients were compared. The results show that the fast cement reduces setting time by an average of one minute and 55 seconds (p < 0.01) and presents similar manipulation characteristics to those of conventional cement.

Change of tribological properties has been the main goal in the effort to augment the longevity of total hip arthroplasty, while the reduction of forces acting across the artificial joint space has received little attention. Spurred by recent reports of wear behaviour and good clinical results of the offset low friction arthroplasty cups, the authors, using the simplified free body technique, estimated the resultant hip joint reaction force and the angle of its application on 100 individual anteroposterior pelvic radiographs, by templating on the same hip a conventional concentric cup and an offset eccentric one. The results showed a highly significant reduction (p<0.0001) of the resultant hip joint reaction force in the offset group by 28.8% or 1.02 body weight and of the angle of the hip joint reaction force by 2.8 degrees. The authors believe that the reduction of the resultant hip joint reaction force in the offset cup group is the result of lowering and medialising the centre of rotation of the hip, a previously reported fact on non-clinically applicable conditions. They are also tempted to propose the generalized use of the offset type acetabular cup, since adverse events are not anticipated.

Between 1996 and 2002, we treated 60 patients (65 hips) by hip resurfacing. The notes and radiographs of these cases were studied retrospectively and the modalities of failure identified. At a mean follow-up of 51 months, 14 of these cases (22%) required revision surgery. One patient had died from unrelated causes and one was lost to follow-up. At the time of primary surgery, the mean age of the patients in our series was 55 years. The commonest mechanism of failure in our series was fractured neck of femur (six cases). Four of these occurred in females over the age of 60. None of the fractured necks of femur were associated with trauma. There were four cases of loose acetabular components and one case of progressive AVN (avascular necrosis). Two patients required revision surgery for ongoing hip pain and one required a two-stage revision for early deep infection.

Approximately 10% of primary hip replacements performed each year for osteoarthritis are in patients aged 55 or younger. These patients have a longer life expectancy and a higher activity level than an older cohort, which may translate to higher revision rates.

We utilized a regional hip register (Trent and Welsh Arthroplasty Audit Group (TWAAG)) to review current surgical practice in this age group.

From 01/01/2000 – 31/12/2002, we were notified of 7,678 primary THRs for osteoarthritis. Of these 911 (11.7%) were performed on patients aged 55 or less. Age, gender, grade of lead operating surgeon, type of femoral and acetabular prostheses implanted, fixation method, femoral head size and bearing surfaces were recorded. There were 434 males and 477 females, with an age range of 16–55. Thirty-five femoral and 33 acetabular components were identified: 61.7% of femoral prostheses were cemented; 67.4 % of acetabular prostheses were uncemented. Fifty per cent of implants had a metal/UHMWPE bearing. Other bearing surfaces comprised ceramic/UHMWPE 28.7%, metal/metal resurfacing 13.8% and ceramic/ceramic 7.5%. Consultants performed 84.5% of procedures.

The study indicates that there does not appear to be a clear consensus as to component choice or optimum fixation method in the younger patient.

The aims were to prospectively assess the mortality risk following proximal hip fractures, identify factors predictive of increased mortality and to investigate the time trends in mortality with comparison to previous studies.

Prospectively collected data from 68 consecutive patients who had been admitted to a regional hospital from May 2001 to September 2001 were reviewed. The mean age of the patients was 79.3 years old (range, 55–98) and 72.1% females. Patients were followed prospectively to determine the mortality risk associated with hip fracture over a two-year follow-up period.

The acute in-hospital mortality rate at six months, one year and two years was 5.9% (4/68), 14.7% (10/68), 20.6% (14/68) and 25% (17/68) respectively. One-year and two-year mortality for those patients who were 80 or older was significantly higher than for other patients and the number of co-morbid illnesses also had significant effect. Cox regression was performed to determine the significant predictors for survival time. It was noted that patients 80 years or older were at higher risk of death compared with those less than 80 years as well as those with higher number of co-morbid illnesses. Our mortality rates have not declined in the past 10 years when compared with previous local studies. We conclude that for this group of patients studied, their mortality at one year and two years could be predicted by their age group and their number of co-morbid illnesses.

Deep infection complicating arthroplasty surgery carries a heavy financial and emotional burden on any orthopaedic service. The cost of hospital acquired infection is estimated at £1 billion per year by the National Audit Office. Healthcare associated infection is an area currently under great scrutiny.

The Alexandra Hospital, Redditch, has developed a dedicated elective orthopaedic ward free from methicillin-resistant Staphylococcus aureus (MRSA) that delivers high quality and high volume major joint replacement surgery through rigorous infection control.

Between October 2001 and December 2002, the Alexandra Hospital had an infection rate of 0.21% for total knee replacements compared to the national rate of 2.1% p= 0.002 (CI 0.00005-0.01) The infection rate for total hip replacements was 1.31% compared to 3.8% nationwide. p= 0.01 (CI 0.004- 0.03).

The total number of joint replacements performed per year, utilising the same number of elective beds, increased from 482 in 2001 to 629 in 2002.

We believe that the MRSA screening policy and subsequent altered bed utilisation have contributed to lowering the rate of infection and improved efficiency.

We have developed a safe, effective and efficient orthopaedic unit within the framework of an acute NHS trust. We believe the practical changes and modest investment that have been made within our department can be repeated in other units around the country with relative ease.

Arthrography is useful in the evaluation and treatment of developmental dysplasia of the hip. The authors describe the additional diagnostic value obtained from a “false profile” arthrogram. The “false profile” arthrogram allows assessment of anterior acetabulum cover, femoral neck anteversion and hip joint subluxation (instability), which may not be apparent on other views.

Acetabular extrusion of cement during total hip arthroplasty is a well-recognised occurrence. We report a case of femoral neuropathy secondary to an extruded cement mass nine years after primary cemented total hip arthroplasty. Removal of the cement resulted in resolution of the patient's symptoms.