Introduction: A major concern with cemented hip resurfacing arthroplasty (HRA) femoral components is the thermal damage to femoral head during cement curing; this maybe linked to fracture (reported incidence ~2%) and early failure. We investigated the effect of a modifid surgical technique using pulse lavage, lesser trochanter suction and early reduction on the maximum temperature recorded in the femoral head during HRA, compared to manual lavage and reduction after cement curing.

Methods: Patients undergoing total hip replacement (THR) were given a dummy HRA procedure, during which a temperature probe was inserted into the femoral head and the measuring tip placed close to the reamed surface; the position of the probe was confirmed by inter-operative xray. Four subjects received a dummy HRA femoral component using manual lavage and Simplex cement. The implanted femur was kept dislocated until the cement cured. The implanted heads were then removed and sectioned to locate the temperature probes, the THR surgery was then performed. Five patients receiving a definitive HRA were also measured; for these subjects suction on the lesser trochanter was used, pulse lavage given for 30 seconds prior to cementing with Simplex, and pulse lavage of the femoral head for 2 minutes, applied 1 minute after cementing the femoral component. The implanted joint was then immediately reduced and a further two minutes of pulse lavage applied to the reduced joint. Temperatures were recorded until the cement finally cured. In every case the cement was hand mixed for 1 minute and the component implanted at 2 minutes 30 seconds after mixing began.

Results: Sectioning showed that probe tips were < 0.5mm from cement mantle. The maximum temperature recorded in the femoral head was significantly (p=0.014) greater for the manual technique, median value of 47.2°C (37.0 to 67.9°C), than for the pulse lavage technique, median value of 32.7°C (31.7 to 35.6°C).

Discussion: The results show that excessive bone temperatures can occur during hip resurfacing. Temperatures above 45°C kill bone cells, the manual technique may lead to substantial thermal necrosis. Technique modification, with the use of suction on the lesser trochanter, generous use of pulse-lavage and joint reduction prior to cement curing, significantly reduced the temperatures recorded. With the modified technique, the maximum temperatures were well below the threshold of thermal damage. This modified technique is recommended as the potential for thermal bone necrosis is significantly reduced.

We examined the relationships between the serum levels of chromium and cobalt ions and the inclination angle of the acetabular component and the level of activity in 214 patients implanted with a metal-on-metal resurfacing hip replacement. Each patient had a single resurfacing and no other metal in their body. All serum measurements were performed at a minimum of one year after operation. The inclination of the acetabular component was considered to be steep if the abduction angle was greater than 55°.

There were significantly higher levels of metal ions in patients with steeply-inclined components (p = 0.002 for chromium, p = 0.003 for cobalt), but no correlation was found between the level of activity and the concentration of metal ions. A highly significant (p < 0.001) correlation with the arc of cover was found. Arcs of cover of less than 10 mm were correlated with a greater risk of high concentrations of serum metal ions. The arc of coverage was also related to the design of the component and to size as well as to the abduction angle of the acetabular component. Steeply-inclined acetabular components, with abduction angles greater than 55°, combined with a small size of component are likely to give rise to higher serum levels of cobalt and chromium ions. This is probably due to a greater risk of edge-loading.

Dislocation rates after total hip arthroplasty vary from 1% to 8% and approximately 1% will require revision surgery to treat hip instability. From these revisions only 60% is successful with redislocation frequencies from 8.2% to 39%. A full-constrained acetabular cup can be used by hip surgeons as a measure of salvage. The purpose of this paper is to describe the complications the authors have encountered in a short postoperative period with the use of three different types of full-constrained acetabular cups.

Over a period of three years, between January 1999 and December 2001, 25 full-constrained acetabular components were implanted. Three different types of full-constrained prostheses were used: the Osteonics Bipolar Constrained Insert (Osteonics Corp., Allendale, NJ), the Ringloc Constrained Liner (Biomet Inc., Warsaw, IN) and the Trilogy Constrained Liner (Zimmer Inc., Warsaw, IN). In 14 cases the full-constrained cups were used in revision hip arthroplasty and in 4 cases as revision for failed full-constrained implants. Seven patients received a primary constrained acetabular prosthesis.

Of the 23 patients one woman died after a follow-up period of 25.5 months. The other 22 patients had an average clinical follow-up of 22.5 months, ranging from 16 to 47.5 months. In 8 prostheses 6 different postoperative problems were encounterd, resulting in a total of 32 % failures. Seven of the complications were different types of constrained acetabular cup disassembly and one complication was due to a failure at the interface between bone and the porous-metal surface. As alternative treatment option, the authors have used the Birmingham Hip Resurfacing (Midland Medical Technologies, Birmingham) Dysplasia cup with modular head in seven patients who sustained recurrent dislocations after multiple revision surgery, with only one failure (1/7 - recurrent dislocation) after a mean follow-up of two years.

In view of the high short-term complication rate (32%) in a follow-up period of three years, the authors strongly recommend judicious use of the constrained acetabular prosthesis. The component should only be applied as a salvage tool in selected patients in whom no other treatment options would be successful. In these cases the use of a constrained acetabular prosthesis might solve the problems encountered in the majority of patients, but it can never guarantee a problem-free course of this cup. Alternative options such as the use of large diameter femoral heads with a resurfacing cup, using a metal-on-metal friction couple should be considered as a worthwhile alternative in those cases.

Postoperative dislocations are known to be a big problem in revision surgery. In literature dislocation rates vary from 4.8% to 33% after previous surgery. In revision surgery, impingement of the implant components, the capsular and soft tissue release, muscular weakness and greater trochanter problems can give additional instability. The reason for revision is important, where instability, infection and tumour cases will lead to a higher percentage of dislocations. The use of big metal heads on polyethylene should be avoided because of the higher volumetric wear. With the new developments of metal-on-metal hip resurfacing and the production of big modular metal heads, the metal-on-metal bearing should guarantee a low-wear result without osteolysis.

Between November 2000 and December 2003 45 patients requiring a revision were treated with a Birmingham Hip Resurfacing cup (MMT, UK) and a big metal-on-metal modular head. All surgery was done with a posterolateral approach. Cup sizes range from 44 to 66 mm, head sizes range from 38 to 58 mm. The head sizes most often used were 58 mm, 54 mm and 50 mm. All patients were prospective followed using the Orthowave software (CRDA France).

In this series of 45 revisions (mean age 56.17) with large modular heads we encountered 2 dislocations, which give us a dislocation rate of 4.4%. One of these dislocations became recurrent and was revised to a full-constrained acetabular component.

Our own dislocation rate in revision hip surgery is 13% (21/159) in the anterolateral approach. Dislocations using the posterolateral approach increased this percentage to 14.8% (21/141). Taking in account that 31% of the causes of revision were infection and recurrent dislocation, this trial demonstrates that large diameter ball heads give beside a better range of movement also a statistically proven reduction in the dislocation rate in revision hip surgery.

The difference in outcome after uncemented ceramic-on-ceramic total hip and metal-on-metal resurfacing is looked at in comparable patient groups. Theoretical advantages in resurfacing are less bone resection, normal femoral loading, avoidance of stress shielding and restoration of normal anatomy. In addition, reduced risk of dislocation, less leg lengthening and easier revision should convince us to perform metal-on-metal resurfacing. These advantages of resurfacing, the subjective “better feeling” and having a more “normal” joint is illustrated by objective proof with functional scores and activity.

The first 250 cases of 1067 (September 1998 –March 2004) performed Birmingham Hip resurfacings (MMT, UK) (follow up 2–5 years, mean age 49.54) were scored clinically and functionally. In the same period (July 1996 – September 2003) 164 ceramic-on-ceramic Ancafit total uncemented prostheses (Wright Medical, US) were implanted inthe same age and activity group as the resurfacings. The first group of 126 patients (follow up 2 – 6 years, mean age 46.76) was compared with the resurfacing group. All the data were collected intra operatively and postoperatively, mostly in a prospective way.

At the most recent follow-up there was a significant statistical difference in Harris Hip Scores (global and total), and activity function between the 2 types of pros-theses. Resurfacing scored a Harris Hip Total of 97.9 (ceramic THA 92.1). Of the resurfacing patients 60.71 had a strenuous activity (ceramic THA 30.43). Dislocation rate in resurfacing group was 0.4% (ceramic THA 3%).

The early clinical results in the group of metal-on-metal resurfacing are very satisfactory with Harris and PMA scores indicating early clinical success. The high percentage of strenuous activity in this young patient group satisfies the expectations of the resurfacing. The difference with a normal uncemented hip is stated with a better outcome in Harris Hip Scores and a better activity level.

A prospective study of serum and urinary ion levels was undertaken in a triathlete who had undergone a metal-on-metal resurfacing arthroplasty of the hip four years previously. The one month study period included the final two weeks of training, the day of the triathlon, and the two weeks immediately post-race. Serum cobalt and chromium levels did not vary significantly throughout this period, including levels recorded on the day after the 11-hour triathlon. Urinary excretion of chromium increased immediately after the race and had returned to pre-race levels six days later. The clinical implications are discussed.

Introduction: The purpose of this retrospective study is to compare long-term whole blood metal ion concentrations (Co, Cr, Ni, Mo) between two different metal-on-metal total hip arthroplasties and a metal-on-polyethylene control group, in relationship with physical activity.

Materials and methods: Between 1996 and 2000, different conventional prosthetic designs were implanted at our hospital. For this study, three groups were chosen according to the bearing surfaces used. Patients who had undergone other surgical interventions with implantation of potential sources of Cr/Co were excluded. Patients taking medication or dietary supplements containing Cr/Co were also excluded. In group 1, 17 patients with a 28 mm metal-on-metal bearing, type Metasul (Zimmer), were included. Group 2 comprised 11 patients with a 28 mm metal-on-metal bearing, type M2a (Biomet). The control group consisted of 9 patients with a 28 mm metal-on-polyethylene bearing in combination with a cemented CoCr stem. The three groups were demographically comparable. The postoperative clinical performance was evaluated using the Harris hip score and the Merle-dAubigne score. The activity level was measured using the Baecke questionnaire. Whole blood samples were taken in a standardized way and analysed by high resolution inductively coupled plasma mass spectrometer analysis.

Results: At an average follow-up of 4 years, the mean Harris Hip Score was 88.35 in group 1, 82.64 in group 2 and 90.89 in the control group. The mean Baecke Activity Score was 7.32 in group 1, 5.51 in group 2 and 6.49 in the control group. The mean Cr level was 0.27 in group 1, 0.63 in group 2 and 0.19 in the control group. The mean Co level was 0.63 in group 1, 1.06 in group 2 and 0.51 in the control group. The mean Ni level was 1.11 in group 1, 1.10 in group 2 and 1.31 in the control group. The mean Mo level was 0.65 in group 1, 0.77 in group 2 and 0.56 in the control group.

Conclusions: At a minimum follow-up of 4 years, no statistically significant differences were seen in clinical outcomes among the three groups. The only statistically significant difference in metal ion concentration among the three groups was observed for the Cr concentration between the M2a group and the metal-on-polyethylene group. There is also a positive correlation between the ion concentrations (Cr and Co) on the one hand and the activity level and Body Mass Index on the other.

We present the results of our initial experience with the use of the Birmingham metal-on-metal Hip Resurfacing. The Birmingham Hip Resurfacing(BHR) consists of a high carbon chrome cobalt uncemented hydroxyapatite cupand a cemented femoral component. For patients with severe dysplasia adysplasia cup with screws was used. We utilise this kind of prosthesis for the younger patients (< 65 year). Excellent clinical results are encountered; none of the early problems aswith the old Wagner resurfacing (metal-on-poly) are seen. Our early results are similar to the encouraging results of the series of D.McMinn/R.Treacy.

From September 1998 through April 2001, 185 BHR arthroplasties were performed. The mean age was 49.7 year (16–75). More male patients were operated with this method than female patients (64%–36%). The aetiology was osteoarthritis (81%), necrosis (9%), dysplasia (CDH) (6.6%).

Results: The last 115 patients were reviewed with a follow up from 1 month to 2.5year. Only two patients were lost for follow-up because of death. There was no pain in 92.3% of the cases. The total Harris Hip Score had a mean of97.91, a median score of 100 (71–100). Merle d’Aubigné total Score was 17.36 (12–18). There was a strenuous activity in 70.2% of the patients.

The mean length of stay in hospital was six days (range: 2–26). Complications were: One fractured neck of femur, one ischial nerve palsy and one guide pin was left in the femur. All patients were followed on regular basis and the X-rays were studied for angle of preoperative neck of femur, postoperative angle of the femoral component, angle of cup placement and the parallelism of both components.

Conclusion: Performing only alternate bearings in patients under the age of 75, the metal-on-metal Birmingham Hip Resurfacing looks a good alternative in young active patients and the results are promising.