Aims. Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors. Methods. Between January 2006 and June 2007, a total of 121 patients underwent THA using either an uncemented (Accolade I, made of Ti. 12. Mo. 6. Zr. 2. Fe; Stryker, USA) or a cemented (ABG II, made of cobalt-chrome-molybdenum (CoCrMo); Stryker) femoral component, both with a V40 taper (Stryker). Uncemented acetabular components (Trident; Stryker) with crosslinked polyethylene liners and CoCr femoral heads of 36 mm diameter were used in all patients. At a mean folllow-up of 10.8 years (SD 1.1), 94 patients (79%) were eligible for follow-up (six patients had already undergone a revision, 15 had died, and six were lost to follow-up). A total of 85 THAs in 80 patients (mean age 61 years (24 to 75); 47 (56%) were female) underwent clinical and radiological evaluation, including the measurement of whole blood levels of cobalt and chrome. Metal artifact reduction sequence MRI scans of the hip were performed in 71 patients. Results. A total of 20 ALTRs were identified on MRI, with an incidence of 26%. Patients with ALTR had significantly higher median Co levels compared with those without ALTR (2.96 μg/l (interquartile range (IQR) 1.35 to 4.98) vs 1.44 μg/l (IQR 0.79 to 2.5); p = 0.019). Radiological evidence of osteolysis was also significantly associated with ALTR (p = 0.014). Median Cr levels were not significantly higher in those with ALTR compared with those without one (0.97 μg/l (IQR 0.72 to 1.9) v 0.67 μg/l (IQR 0.5 to 1.19; p = 0.080). BMI, sex, age, type of femoral component, head length, the inclination of the acetabular component, and heterotopic ossification formation showed no significant relationship with ALTR. Conclusion. Due to the high incidence of local ALTR in our cohort after more than ten years postoperatively, we recommend regular follow-up investigation even in asymptomatic patients with V40 taper and metal heads. As cobalt levels correlate with ALTR occurrence, routine metal ion screening and consecutive MRI investigation upon elevation could be discussed. Cite this article: Bone Joint J 2022;104-B(7):852–858

Aims. Dual mobility (DM) implants have been shown to reduce the dislocation rate after total hip arthroplasty (THA), but there remain concerns about the use of cobalt chrome liners inserted into titanium shells. The aim of this study was to assess the clinical outcomes, metal ion levels, and periprosthetic femoral bone mineral density (BMD) at mid-term follow-up in young, active patients receiving a modular DM THA. Methods. This was a prospective study involving patients aged < 65 years, with a BMI of < 35 kg/m. 2. , and University of California, Los Angeles activity score of > 6 who underwent primary THA with a modular cobalt chrome acetabular liner, highly cross-linked polyethylene mobile bearing, and a cementless titanium femoral stem. Patient-reported outcome measures, whole blood metal ion levels (μg/l), and periprosthetic femoral BMD were measured at baseline and at one, two, and five years postoperatively. The results two years postoperatively for this cohort have been previously reported. Results. A total of 43 patients were enrolled. At minimum follow-up of five years, 23 (53.4%) returned for clinical and radiological review, 25 (58.1%) had metal ion analysis performed, 19 (44.2%) underwent dual energy x-ray absorptiometry scans, and 25 (58%) completed a pain-drawing questionnaire. The mean modified Harris Hip Scores improved significantly from 54.8 (SD 19) preoperatively to 93.08 (SD 10.5) five years postoperatively (p < 0.001). One patient was revised for aseptic acetabular loosening. The mean cobalt levels increased from 0.065 μg/l (SD 0.03) to 0.08 (SD 0.05) and the mean titanium levels increased from 0.35 (SD 0.13) to 0.78 (SD 0.29). The femoral BMD ratio decreased in Gruen Zone 1 (91.9%) at five years postoperatively compared with the baseline scores at six weeks potoperatively. The femoral BMD ratio was maintained in Gruen zones 2 to 7. Conclusion. The use of a modular DM component and a cementless, tapered femoral stem shows excellent mid-term survivorship with minimal concerns for corrosion and metal ion release in a cohort of young, active patients undergoing primary THA. Cite this article: Bone Joint J 2021;103-B(7 Supple B):73–77

Aims. This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads. Methods. In all, six 28 mm and six 36 mm titanium stem-cobalt chrome head pairs with polyethylene sockets were tested in a novel instrumented hip simulator. Samples were tested using simulated gait data with incremental increasing loads to determine corrosion onset load and electrochemical activity. Half of each head size group were then cycled with simulated gait and the other half with gait compression only. Damage was measured by area and maximum linear wear depth. Results. Overall, 36 mm heads had lower corrosion onset load (p = 0.009) and change in open circuit potential (OCP) during simulated gait with (p = 0.006) and without joint movement (p = 0.004). Discontinuing gait’s joint movement decreased corrosion currents (p = 0.042); however, wear testing showed no significant effect of joint movement on taper damage. In addition, 36 mm heads had greater corrosion area (p = 0.050), but no significant difference was found for maximum linear wear depth (p = 0.155). Conclusion. Larger heads are more susceptible to taper corrosion; however, not due to frictional torque as hypothesized. An alternative hypothesis of taper flexural rigidity differential is proposed. Further studies are necessary to investigate the clinical significance and underlying mechanism of this finding. Cite this article: Bone Jt Open 2021;2(11):1004–1016

Aims

Radiostereometric analysis (RSA) is the most accurate radiological method to measure in vivo wear of highly cross-linked polyethylene (XLPE) acetabular components. We have previously reported very low wear rates for a sequentially irradiated and annealed X3 XLPE liner (Stryker Orthopaedics, USA) when used in conjunction with a 32 mm femoral heads at ten-year follow-up. Only two studies have reported the long-term wear rate of X3 liners used in conjunction with larger heads using plain radiographs which have poor sensitivity. The aim of this study was to measure the ten-year wear of thin X3 XLPE liners against larger 36 or 40 mm articulations with RSA.

Aims

In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced corrosion can lead to elevated serum metal ions, a local inflammatory response, and formation of pseudotumours, ultimately requiring revision. The size and diametral clearance of anatomical (ADM) and modular (MDM) dual-mobility polyethylene bearings match those of Birmingham hip MoM components. If the acetabular component is satisfactorily positioned, well integrated into the bone, and has no surface damage, this presents the opportunity for revision with exchange of the metal head for ADM/MDM polyethylene bearings without removal of the acetabular component.

Aims

To evaluate the concurrent use of vancomycin and ε-aminocaproic acid (EACA) in primary total hip arthroplasty (THA).

Aims

The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA).

Aims

To establish the survivorship, function, and metal ion levels in an unselected series of metal-on-metal hip resurfacing arthroplasties (HRAs) performed by a non-designer surgeon.

Aims

To achieve the functional benefits of the direct anterior (DA) approach and the fixation benefits of cemented replacement, this study combined the two techniques posing the following questions: does the limited access of the DA approach adversely affect the cement technique?; and does such a cementing technique reduce the incidence of cementless complications?

Aims

The aims of this study were to develop an in vivo model of periprosthetic joint infection (PJI) in cemented hip hemiarthroplasty, and to monitor infection and biofilm formation in real-time.

Aims

Vitamin E-infused highly crosslinked polyethylene (VEPE) has been introduced into total hip arthroplasty (THA) with the aim of further improving the wear characteristics of moderately and highly crosslinked polyethylenes (ModXLPE and HXLPE). There are few studies analyzing the outcomes of vitamin E-infused components in cemented arthroplasty, though early acetabular component migration has been reported. The aim of this study was to measure five-year polyethylene wear and acetabular component stability of a cemented VEPE acetabular component compared with a ModXLPE cemented acetabular component.

Aims

Studying the indications for revision total hip arthroplasty (THA) may enable surgeons to change their practice during the initial procedure, thereby reducing the need for revision surgery. The aim of this study was to identify and describe the potentially avoidable indications for revision THA within five years of the initial procedure.

Aims

We have previously demonstrated raised cobalt and chromium levels in patients with larger diameter femoral heads, following metal-on-polyethylene uncemented total hip arthroplasty. Further data have been collected, to see whether these associations have altered with time and to determine the long-term implications for these patients and our practice.

Aims

We evaluated a large database with mechanical failure of a single uncemented modular femoral component, used in revision hip arthroplasty, as the end point and compared them to a control group treated with the same implant. Patient- and implant-specific risk factors for implant failure were analyzed.

Aims

To present a surgically relevant update of trunnionosis.

Aims

Instability continues to be a troublesome complication after total hip arthroplasty (THA). Patient-related risk factors associated with a higher dislocation risk include the preoperative diagnosis, an age of 75 years or older, high body mass index (BMI), a history of alcohol abuse, and neurodegenerative diseases. The goal of this study was to assess the dislocation rate, radiographic outcomes, and complications of patients stratified as high-risk for dislocation who received a dual mobility (DM) bearing in a primary THA at a minimum follow-up of two years.

Aims

We sought to determine whether cobalt-chromium alloy (CoCr) femoral stem tapers (trunnions) wear more than titanium (Ti) alloy stem tapers (trunnions) when used in a large diameter (LD) metal-on-metal (MoM) hip arthroplasty system.

Aims

Surgeons have commonly used modular femoral heads and stems from different manufacturers, although this is not recommended by orthopaedic companies due to the different manufacturing processes.

We compared the rate of corrosion and rate of wear at the trunnion/head taper junction in two groups of retrieved hips; those with mixed manufacturers (MM) and those from the same manufacturer (SM).

Aims

The aim of this study was to report the initial results of the Exeter V40 stem, which became available in 2000.

Aims

We present a case series of ten metal-on-polyethylene total hip arthroplasties (MoP THAs) with delayed dislocation associated with unrecognised adverse local tissue reaction due to corrosion at the trunnion and pseudotumour formation.

Aims

Femoral stems with exchangeable (modular) necks were introduced to offer surgeons an increased choice when determining the version, offset and length of the femoral neck during total hip arthroplasty (THA). It was hoped that this would improve outcomes and reduce complications, particularly dislocation. In 2010, the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) first reported an increased rate of revision after primary THA using femoral stems with an exchangeable neck. The aim of this study was to provide a more comprehensive up-to-date analysis of primary THA using femoral stems with exchangeable and fixed necks.

Aims

One method of femoral head preservation following avascular necrosis (AVN) is core decompression and insertion of a tantalum rod. However, there may be a high failure rate associated with this procedure. The purpose of this study was to document the clinical and radiological outcomes following total hip arthroplasty (THA) subsequent to failed tantalum rod insertion.

Objectives

This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion.

Aims

To investigate the longevity of uncemented fixation of a femoral component in total hip arthroplasty (THA) in patients with Dorr type C proximal femoral morphology.

Aims

The long-term functional outcome of total hip arthroplasty (THA) performed by trainees is not known. A multicentre retrospective study of 879 THAs was undertaken to investigate any differences in outcome between those performed by trainee surgeons and consultants.

Aims

The purpose of this study was to compare the long-term results of primary total hip arthroplasty (THA) in young patients using either a conventional (CPE) or a highly cross-linked (HXLPE) polyethylene liner in terms of functional outcome, incidence of osteolysis, radiological wear and rate of revision.

We present a series of 35 patients (19 men and 16 women) with a mean age of 64 years (36.7 to 75.9), who underwent total hip replacement using the ESKA dual-modular short stem with metal on-polyethylene bearing surfaces. This implant has a modular neck section in addition to the modular head. Of these patients, three presented with increasing post-operative pain due to pseudotumour formation that resulted from corrosion at the modular neck-stem junction. These patients underwent further surgery and aseptic lymphocytic vaculitis associated lesions were demonstrated on histological analysis.

Retrieval analysis of two modular necks showed corrosion at the neck-stem taper. Blood cobalt and chromium levels were measured at a mean of nine months (3 to 28) following surgery. These were compared with the levels in seven control patients (three men and four women) with a mean age of 53.4 years (32.1 to 64.1), who had an identical prosthesis and articulation but with a prosthesis that had no modularity at neck-stem junction. The mean blood levels of cobalt in the study group were raised at 50.75 nmol/l (5 to 145) compared with 5.6 nmol/l (2 to 13) in control patients.

Corrosion at neck-stem tapers has been identified as an important source of metal ion release and pseudotumour formation requiring revision surgery. Finite element modelling of the dual modular stem demonstrated high stresses at the modular stem-neck junction. Dual modular cobalt-chrome hip prostheses should be used with caution due to these concerns.

We describe the clinical and radiological results of cementless primary total hip replacement (THR) in 25 patients (18 women and seven men; 30 THRs) with severe developmental dysplasia of the hip (DDH). Their mean age at surgery was 47 years (23 to 89). In all, 21 hips had Crowe type III dysplasia and nine had Crowe type IV. Cementless acetabular components with standard polyethylene liners were introduced as close to the level of the true acetabulum as possible. The modular cementless S-ROM femoral component was used with a low resection of the femoral neck.

A total of 21 patients (25 THRs) were available for review at a mean follow-up of 18.7 years (15.8 to 21.8). The mean modified Harris hip score improved from 46 points pre-operatively to 90 at final follow up (p < 0.001).

A total of 15 patients (17 THRs; 57%) underwent revision of the acetabular component at a mean of 14.6 years (7 to 20.8), all for osteolysis. Two patients (two THRs) had symptomatic loosening. No patient underwent femoral revision. Survival with revision of either component for any indication was 81% at 15 years (95% CI 60.1 to 92.3), with 21 patients at risk.

This technique may reduce the need for femoral osteotomy in severe DDH, while providing a good long-term functional result.

Cite this article: Bone Joint J 2014;96-B:1449–54.

This study reports the mid-term results of a large-bearing hybrid metal-on-metal total hip replacement in 199 hips (185 patients) with a mean follow-up of 62 months (32 to 83).

Two patients died of unrelated causes and 13 were lost to follow-up. In all, 17 hips (8.5%) have undergone revision, and a further 14 are awaiting surgery. All revisions were symptomatic. Of the revision cases, 14 hips showed evidence of adverse reactions to metal debris. The patients revised or awaiting revision had significantly higher whole blood cobalt ion levels (p = 0.001), but no significant difference in acetabular component size or position compared with the unrevised patients. Wear analysis (n = 5) showed increased wear at the trunnion-head interface, normal levels of wear at the articulating surfaces and evidence of corrosion on the surface of the stem.

The cumulative survival rate, with revision for any reason, was 92.4% (95% confidence interval 87.4 to 95.4) at five years. Including those awaiting surgery, the revision rate would be 15.1% with a cumulative survival at five years of 89.6% (95% confidence interval 83.9 to 93.4).

This hybrid metal-on-metal total hip replacement series has shown an unacceptably high rate of failure, with evidence of high wear at the trunnion-head interface and passive corrosion of the stem surface. This raises concerns about the use of large heads on conventional 12/14 tapers.

We report on 397 consecutive revision total hip replacements in 371 patients with a mean clinical and radiological follow-up of 12.9 years (10 to 17.7). The mean age at surgery was 69 years (37 to 93). A total of 28 patients (8%) underwent further revision, including 16 (4%) femoral components. In all 223 patients (56%, 233 hips) died without further revision and 20 patients (5%, 20 hips) were lost to follow-up. Of the remaining patients, 209 (221 hips) were available for clinical assessment and 194 (205 hips) for radiological review at mean follow-up of 12.9 years (10 to 17.7).

The mean Harris Hip Score improved from 58.7 (11 to 92) points to 80.7 (21 to 100) (p <  0.001) and the mean Merle d’Aubigné and Postel hip scores at final follow-up were 4.9 (2 to 6), 4.5 (2 to 6) and 4.3 (2 to 6), respectively for pain, mobility and function. Radiographs showed no lucencies around 186 (90.7%) femoral stems with stable bony ingrowth seen in 199 stems (97%). The survival of the S-ROM femoral stem at 15 years with revision for any reason as the endpoint was 90.5% (95% confidence interval (CI) 85.7 to 93.8) and with revision for aseptic loosening as the endpoint 99.3% (95% CI 97.2 to 99.8).

We have shown excellent long-term survivorship and good clinical outcome of a cementless hydroxyapatite proximally-coated modular femoral stem in revision hip surgery.

Cite this article: Bone Joint J 2014;96-B:730–6.

Large-head metal-on-metal (MoM) total hip replacements (THR) have given rise to concern. Comparative studies of small-head MoM THRs over a longer follow-up period are lacking. Our objective was to compare the incidence of complications such as infection, dislocation, revision, adverse local tissue reactions, mortality and radiological and clinical outcomes in small-head (28 mm) MoM and ceramic-on-polyethylene (CoP) THRs up to 12 years post-operatively.

A prospective cohort study included 3341 THRs in 2714 patients. The mean age was 69.1 years (range 24 to 98) and 1848 (55.3%) were performed in women, with a mean follow-up of 115 months (18 to 201). There were 883 MoM and 2458 CoP bearings. Crude incidence rates (cases/1000 person-years) were: infection 1.3 vs 0.8; dislocation 3.3 vs 3.1 and all-cause revision 4.3 vs 2.2, respectively. There was a significantly higher revision rate after ten years (adjusted hazard ratio 9.4; 95% CI 2.6 to 33.6) in the MoM group, and ten of 26 patients presented with an adverse local tissue reaction at revision. No differences in mortality, osteolysis or clinical outcome were seen.

In conclusion, we found similar results for small-head MoM and CoP bearings up to ten years post-operatively, but after ten years MoM THRs had a higher risk of all-cause revision. Furthermore, the presence of an adverse response to metal debris seen in the small-head MOM group at revision is a cause for concern.

Cite this article: Bone Joint J 2014; 96-B:868–75.

Femoroacetabular impingement (FAI) is commonly associated with early hip arthritis. We reviewed our series of 1300 hip resurfacing procedures. More than 90% of our male patients, with an average age of 53 years, had cam impingement lesions. In this condition, there are anterior femoral neck osteophytes, and a retroverted femoral head on a normally anteverted neck. It is postulated that FAI results in collision of the anterior neck of the femur against the rim of the acetabulum, causing damage to the acetabular labrum and articular cartilage, resulting in osteoarthritis. Early treatment of FAI involves arthroscopic or open removal of bone from the anterior femoral neck, as well as repair or removal of labral tears. However, once osteoarthritis has developed, hip replacement or hip resurfacing is indicated. Hip resurfacing can re-orient the head and re-shape the neck. This helps to restore normal biomechanics to the hip, eliminate FAI, and improve range of motion. Since many younger men with hip arthritis have FAI, and are also considered the best candidates for hip resurfacing, it is evident that resurfacing has a role in these patients.

Large femoral heads have been used with increasing frequency over the last decade. The prime reason is likely the effect of large heads on stability. The larger head neck ratio, combined with the increased jump distance of larger heads result in a greater arc of impingement free motion, and greater resistance to dislocation in a provocative position. Multiple studies have demonstrated clear clinical efficacy in diminishing dislocation rates with the use of large femoral heads. With crosslinked polyethylene, wear has been shown to be equivalent between larger and smaller heads. However, the stability advantages of increasing diameter beyond 38 mm have not been clearly demonstrated. More importantly, recent data implicates large heads in the increasing prevalence of groin pain and psoas impingement. There are clear benefits with larger femoral head diameters, but the advantages of diameters beyond 38 mm have not yet been demonstrated clinically.

A total of 219 hips in 192 patients aged between 18 and 65 years were randomised to 28-mm metal-on-metal uncemented total hip replacements (THRs, 107 hips) or hybrid hip resurfacing (HR, 112 hips). At a mean follow-up of eight years (6.6 to 9.3) there was no significant difference between the THR and HR groups regarding rate of revision (4.0% (4 of 99) vs 5.8% (6 of 104), p = 0.569) or re-operation rates without revision (5.1% (5 of 99) vs 2.9% (3 of 104), p = 0.428). In the THR group one recurrent dislocation, two late deep infections and one peri-prosthetic fracture required revision, whereas in the HR group five patients underwent revision for femoral head loosening and one for adverse reaction to metal debris. The mean University of California, Los Angeles activity scores were significantly higher in HR (7.5 (sd 1.7) vs 6.9 (sd 1.7), p = 0.035), but similar mean Western Ontario and McMaster Universities Osteoarthritis Index scores were obtained (5.8 (sd 9.5) in HR vs 5.1 (sd 8.9) in THR, p = 0.615) at the last follow-up. Osteolysis was found in 30 of 81 THR patients (37.4%), mostly in the proximal femur, compared with two of 83 HR patients (2.4%) (p < 0.001). At five years the mean metal ion levels were < 2.5 μg/l for cobalt and chromium in both groups; only titanium was significantly higher in the HR group (p = 0.001). Although revision rates and functional scores were similar in both groups at mid-term, long-term survival analysis is necessary to determine whether one procedure is more advantageous than the other.

Cite this article: Bone Joint J 2013;95-B:1464–73.

We reviewed the seven- to ten-year results of our previously reported prospective randomised controlled trial comparing total hip replacement and hemiarthroplasty for the treatment of displaced intracapsular fracture of the femoral neck. Of our original study group of 81 patients, 47 were still alive.

After a mean follow up of nine years (7 to 10) overall mortality was 32.5% and 51.2% after total hip replacement and hemiarthroplasty, respectively (p = 0.09). At 100 months postoperatively a significantly greater proportion of hemiarthroplasty patients had died (p = 0.026). Three hips dislocated following total hip replacement and none after hemiarthroplasty. In both the total hip replacement and hemiarthroplasty groups a deterioration had occurred in walking distance (p = 0.02 and p < 0.001, respectively). One total hip replacement required revision compared with four hemiarthroplasties which were revised to total hip replacements. All surviving patients with a total hip replacement demonstrated wear of the cemented polyethylene component and all hemiarthroplasties had produced acetabular erosion.

There was lower mortality (p = 0.013) and a trend towards superior function in patients with a total hip replacement in the medium term.

Peri-articular soft-tissue masses or ‘pseudotumours’ can occur after large-diameter metal-on-metal (MoM) resurfacing of the hip and conventional total hip replacement (THR). Our aim was to assess the incidence of pseudotumour formation and to identify risk factors for their formation in a prospective cohort study.

A total of 119 patients who underwent 120 MoM THRs with large-diameter femoral heads between January 2005 and November 2007 were included in the study. Outcome scores, serum metal ion levels, radiographs and CT scans were obtained. Patients with symptoms or an identified pseudotumour were offered MRI and an ultrasound-guided biopsy.

There were 108 patients (109 hips) eligible for evaluation by CT scan at a mean follow-up of 3.6 years (2.5 to 4.5); 42 patients (39%) were diagnosed with a pseudotumour. The hips of 13 patients (12%) were revised to a polyethylene acetabular component with small-diameter metal head. Patients with elevated serum metal ion levels had a four times increased risk of developing a pseudotumour.

This study shows a substantially higher incidence of pseudotumour formation and subsequent revisions in patients with MoM THRs than previously reported. Because most revision cases were identified only after an intensive screening protocol, we recommend close monitoring of patients with MoM THR.

In 2004 we described the ten-year prospective results of 38 total hip replacements using the Furlong hydroxyapatite-ceramic-coated femoral component in 35 patients < 50 years old. We have now reviewed the surviving 35 arthroplasties in 33 patients at a mean of 16 years (10.3 to 19.9). The mean age of the surviving patients at the time of operation was 41.3 years (26.0 to 49.0). Of these, eight have undergone revision of their acetabular component for aseptic loosening. None of the femoral components has had revision for aseptic loosening giving a survival rate of 100% at 16 years (95% confidence interval 89% to 100%).

The Furlong hydroxyapatite-ceramic-coated femoral component gives excellent long-term survival in young and active patients.

Narrowing of the femoral neck after resurfacing arthroplasty of the hip has been described previously in both cemented and uncemented hip resurfacing. The natural history of narrowing of the femoral neck is unknown. We retrospectively measured the diameter of the femoral neck in a series of 163 Birmingham hip resurfacings in 163 patients up to a maximum of six years after operation to determine the extent and progression of narrowing.

There were 105 men and 58 women with a mean age of 52 years (18 to 82). At a mean follow-up of five years, the mean Harris hip score was 94.8 (47 to 100) and the mean flexion of the hip 112.5° (80° to 160°). There was some narrowing of the femoral neck in 77% (125) of the patients reviewed, and in 27.6% (45) the narrowing exceeded 10% of the diameter of the neck. A multiple logistic regression analysis showed a significant association (chi-squared test (derived from logistic regression) p = 0.01) of narrowing with female gender and a valgus femoral neck/shaft angle. There was no significant association between the range of movement, position or size of the component or radiological lucent lines and narrowing of the neck (chi-squared test; p = 0.10 (flexion), p = 0.08 (size of femoral component), p = 0.09 (size of acetabular component), p = 0.71 (femoral component angulation), p = 0.99 (lucent lines)). There was no significant difference between the diameter of the neck at a mean of three years (2.5 to 3.5) and that at five years (4.5 to 5.5), indicating that any change in the diameter of the neck had stabilised by three years (sign rank test, p = 0.60).

We conclude that narrowing of the femoral neck which is found with the Birmingham hip resurfacing arthroplasty is in most cases associated with no adverse clinical or radiological outcome up to a maximum of six years after the initial operation.

We retrospectively reviewed 175 patients (191 hips) who had undergone primary cemented total hip replacement between November 1992 and November 1995 using a collarless polished double-tapered femoral component after a minimum of ten years (mean 11.08; 10 to 12.8). All stems were implanted using contemporary cementing techniques with a distal cement restrictor, pressurised lavage, retrograde cementing with a gun and proximal pressurisation. Clinical outcome was assessed using the Harris Hip score. Radiological analysis was performed on calibrated plain radiographs taken in two planes. Complete radiological data on 110 patients (120 hips) and clinical follow-up on all the surviving 111 patients (122 hips) was available. The fate of all the hips was known.

At final follow-up, the mean Harris Hip score was 86 (47 to 100), and 87 of 116 patients (75%) had good or excellent scores. Survival with revision of the stem for aseptic loosening as the endpoint was 100%; and survival with revision of the stem for any reason was 95.9% (95% confidence interval 87.8 to 96.8) at ten years. All the stems subsided vertically at the stem-cement interface in a predictable pattern, at an overall mean rate of 0.18 mm per year (0.02 to 2.16), but with a mean rate of 0.80 mm (0.02 to 2.5) during the first year. The mean total subsidence was 1.95 mm (0.21 to 24). Only three stems loosened at the cement-bone interface. There was excellent preservation of proximal femoral bone stock. There was a high incidence of Brooker III and IV heterotopic ossification affecting 25 patients (22%).

The collarless polished tapered stem has an excellent clinical and radiological outcome at a minimum of ten years’ follow-up. The pattern and magnitude of subsidence of the stem within the cement mantle occurred in a predictable pattern, consistent with the design philosophy.

There have been no large comparative studies of the blood levels of metal ions after implantation of commercially available hip resurfacing devices which have taken into account the effects of femoral size and inclination and anteversion of the acetabular component. We present the results in 90 patients with unilateral articular surface replacement (ASR) hip resurfacings (mean time to blood sampling 26 months) and 70 patients with unilateral Birmingham Hip Resurfacing (BHR) implants (mean time 47 months).

The whole blood and serum chromium (Cr) and cobalt (Co) concentrations were inversely related to the size of the femoral component in both groups (p < 0.05). Cr and Co were more strongly influenced by the position of the acetabular component in the case of the ASR, with an increase in metal ions observed at inclinations > 45° and anteversion angles of < 10° and > 20°. These levels were only increased in the BHR group when the acetabular component was implanted with an inclination > 55°.

A significant relationship was identified between the anteversion of the BHR acetabular component and the levels of Cr and Co (p < 0.05 for Co), with an increase observed at anteversion angles < 10° and > 20°. The median whole blood and serum Cr concentrations of the male ASR patients were significantly lower than those of the BHR men (p < 0.001). This indicates that reduced diametral clearance may equate to a reduction in metal ion concentrations in larger joints with satisfactory orientation of the acetabular component.

We describe the results at five years of a prospective study of a new tri-tapered polished, cannulated, cemented femoral stem implanted in 51 patients (54 hips) with osteoarthritis. The mean age and body mass index of the patients was 74 years and 27.9, respectively. Using the anterolateral approach, half of the stems were implanted by a consultant orthopaedic surgeon and half by six different registrars. There were three withdrawals from the study because of psychiatric illness, a deep infection and a recurrent dislocation. Five deaths occurred prior to five-year follow-up and one patient withdrew from clinical review.

In the remaining 51 hips the mean pre-operative Oxford hip score was 47 points which decreased to 19 points at five years (45 hips). Of the stems 49 (98%) were implanted within 1° of neutral in the femoral canal. The mean migration of the stem at five years was 1.9 mm and the survivorship for aseptic loosening was 100%. There was no significant difference in outcome between the consultant and registrar groups. At five years, the results were comparable with those of other polished, tapered, cemented stems. Long-term surveillance continues.

We carried out a clinical and radiological review of 103 cementless primary hip arthroplasties with a tapered rectangular grit-blasted titanium press-fit femoral component and a threaded conical titanium acetabular component at a mean follow-up of 14.4 years (10.2 to 17.1).

The mean Harris hip score at the last follow-up was 89.2 (32 to 100). No early loosening and no fracture of the implant were found. One patient needed revision surgery because of a late deep infection. In 11 hips (10.7%), the reason for revision was progressive wear of the polyethylene liner. Exchange of the acetabular component because of aseptic loosening without detectable liner wear was carried out in three hips (2.9%).

After 15 years the survivorship with aseptic loosening as the definition for failure was 95.6% for the acetabular component and 100% for the femoral component.

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26).

At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision.

Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.