Aims. Despite higher rates of revision after total hip arthroplasty (THA) being reported for uncemented stems in patients aged > 75 years, they are frequently used in this age group. Increased mortality after cemented fixation is often used as a justification, but recent data do not confirm this association. The aim of this study was to investigate the influence of the design of the stem and the type of fixation on the rate of revision and immediate postoperative mortality, focusing on the age and sex of the patients. Methods. A total of 333,144 patients with primary osteoarthritis (OA) of the hip who underwent elective THA between November 2012 and September 2022, using uncemented acetabular components without reconstruction shells, from the German arthroplasty registry were included in the study. The revision rates three years postoperatively for four types of stem (uncemented, uncemented with collar, uncemented short, and cemented) were compared within four age groups: < 60 years (Young), between 61 and 70 years (Mid-I), between 71 and 80 years (Mid-II), and aged > 80 years (Old). A noninferiority analysis was performed on the most frequently used designs of stem. Results. The design of the stem was found to have no significant influence on the rate of revision for either sex in the Young group. Uncemented collared stems had a significantly lower rate of revision compared with the other types of stem for females in the Mid-I group. There was a significantly higher rate of revision for uncemented stems in females in the Mid-II group compared with all other types of stem, while in males the rate for uncemented stems was only significantly higher than the rate for cemented stems. Cemented stems had a significantly lower revision rate compared with uncemented and short stems for both sexes in the Old cohort, as did females with collared stems. The rate of immediate postoperative mortality was similar for all types of stem in the Old age group, as were the American Society of Anesthesiologists grades. Conclusion. In patients aged > 80 years, uncemented and short stems had significantly higher revision rates compared with cemented and collared stems, especially in females. The design of the stem and type of fixation have to be analyzed in more detail than only considering cemented and uncemented fixation, in order to further improve the success of THA. Cite this article: Bone Joint J 2024;106-B(3 Supple A):130–136

Total hip and knee arthroplasty (THA, TKA) are largely successful procedures; however, both have variable outcomes, resulting in some patients being dissatisfied with the outcome. Surgeons are turning to technologies such as robotic-assisted surgery in an attempt to improve outcomes. Robust studies are needed to find out if these innovations are really benefitting patients. The Robotic Arthroplasty Clinical and Cost Effectiveness Randomised Controlled Trials (RACER) trials are multicentre, patient-blinded randomized controlled trials. The patients have primary osteoarthritis of the hip or knee. The operation is Mako-assisted THA or TKA and the control groups have operations using conventional instruments. The primary clinical outcome is the Forgotten Joint Score at 12 months, and there is a built-in analysis of cost-effectiveness. Secondary outcomes include early pain, the alignment of the components, and medium- to long-term outcomes. This annotation outlines the need to assess these technologies and discusses the design and challenges when conducting such trials, including surgical workflows, isolating the effect of the operation, blinding, and assessing the learning curve. Finally, the future of robotic surgery is discussed, including the need to contemporaneously introduce and evaluate such technologies. Cite this article: Bone Joint J 2024;106-B(2):114–120

Aims

The primary outcome was investigating differences in wear, as measured by femoral head penetration, between cross-linked vitamin E-diffused polyethylene (vE-PE) and cross-linked polyethylene (XLPE) acetabular component liners and between 32 and 36 mm head sizes at the ten-year follow-up. Secondary outcomes included acetabular component migration and patient-reported outcome measures (PROMs) such as the EuroQol five-dimension questionnaire, 36-Item Short-Form Health Survey, Harris Hip Score, and University of California, Los Angeles Activity Scale (UCLA).

Aims

BoneMaster is a thin electrochemically applied hydroxyapatite (HA) coating for orthopaedic implants that is quickly resorbed during osseointegration. Early stabilization is a surrogacy marker of good survival of femoral stems. The hypothesis of this study was that a BoneMaster coating yields a fast early and lasting fixation of stems.

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

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.

Aims

Of growing concern in arthroplasty is the emergence of atypical infections, particularly Cutibacterium (formerly Propionibacterium) sp. infections. Currently, the dermal colonization rate of Cutibacterium about the hip is unknown. Therefore, the aim of this study was to investigate colonization rates of Cutibacterium sp. at locations approximating anterior and posterolateral approaches to the hip joint.

Aims

Radiostereometric analysis (RSA) studies of vitamin E-doped, highly crosslinked polyethylene (VEPE) liners show low head penetration rates in cementless acetabular components. There is, however, currently no data on cemented VEPE acetabular components in total hip arthroplasty (THA). The aim of this study was to evaluate the safety of a new cemented VEPE component, compared with a conventional polyethylene (PE) component regarding migration, head penetration, and clinical results.

It is estimated that approximately 3.1 – 7.7% of the general population suffers from primary osteoarthritis of the hip, with up to 42% of these cases being bilateral. The odds of undergoing a contralateral THA after index unilateral THA range from 16–85%. Up to 20% of these patients have the contralateral THA within 5 years. For this patient population, simultaneous bilateral THA may be an appealing option but it remains controversial. Proponents of bilateral simultaneous THA cite advantages such as a single anesthetic exposure, overall shorter length of hospital stay, quicker recovery, earlier return to function, less time off of work, and potential economic advantages. Only recently has there been more data emerging on patients undergoing simultaneous bilateral THA through the direct anterior approach (DAA). The DAA has the distinct advantage of supine positioning that facilitates easy exposure to both hips without the need to reposition the patient onto a fresh surgical incision while performing the second operation. Recent publications suggest that bilateral simultaneous DAA is a safe procedure and may have economic benefits as well. At our institution between 2010 and 2016, a consecutive series of 105 patients (210 hips) undergoing simultaneous bilateral DAA THA and a matched group of 217 patients undergoing unilateral DAA THA by the same surgeon at a single institution were reviewed. The two groups were matched by gender, age, body mass index and date of surgery. There were no significant differences between the two groups in terms of early complications. There were 2 complications in the unilateral group that were intraoperative nondisplaced calcar fractures that were treated with a single cerclage cable and 50% weight bearing for four weeks. There were 6 in-hospital systemic complications in the unilateral group compared to 7 in the bilateral group (p = 0.129). In-hospital systemic complications were similar between the two groups and included urinary retention, cardiopulmonary abnormalities, alcohol withdrawal, and nausea / vomiting. There were a total of 14 30-day follow-up hip-related complications in the unilateral group compared to 5 in the bilateral group (p = 0.06) These complications were similar between the two groups and included wound healing issues, tendinitis / bursitis, deep infection, nerve palsy, stem subsidence, and instability. Intraoperative estimated blood loss (EBL) was 360cc in the unilateral group compared to 555cc in the bilateral group (p < 0.001). The bilateral group had lower postoperative day one (POD1) hemoglobin (9.5 g/dl vs. 10.2 g/dl; p < 0.001). Four percent of unilateral patients required blood transfusion compared to 11% in the bilateral group. There were significant differences between the two groups in terms of distance ambulated on POD1 and length of stay (LOS). On average, the unilateral patients walked 235 feet on POD1 compared to 182 feet for the bilateral patients (p < 0.001). Length of stay was significantly longer in the bilateral group (1.95 days vs. 1.12 days; p < 0.001). All 322 patients involved in the study were discharged to home except for a single patient in the bilateral group who was discharged to a skilled nursing facility. In conclusion, we found no difference in in-hospital or 30-day complication rates when comparing the simultaneous bilateral group to the unilateral group. The main difference when compared to unilateral surgery is increased blood loss yet this did not directly result in specific complications. Simultaneous bilateral DAA THA can be performed safely and without an unacceptably high perioperative complication rate

Introduction. Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of THA, as well as surgical approach, on gait kinetics and kinematics. Purpose. The purpose of this study was to determine the impact of surgical approach for THA on quantitative gait analysis. Methods. Thirty patients undergoing THA for primary osteoarthritis of the hip were assigned to one of three surgical approaches (10 anterior, 10 posterior, and 10 lateral). A single surgeon performed each individual approach. Each patient received standardized implants at the time of surgery (cementless stem and acetabular component, cobalt chrome femoral head, highly cross-linked liner). Patients underwent 3D gait analysis pre-operatively, and at 6- and 12-weeks following the procedure. At each time point, temporal gait parameters, kinetics, and kinematics were compared. Statistical analysis was performed using one-way analysis of variance. Results. All three groups were similar with respect to age (p=0.27), body mass index (p=0.16), and the Charlson Comorbidity Index (p=0.66). Temporal parameters including step length, stride length, gait velocity, and percent stance and swing phase were similar between the groups at all time points. The lateral cohort had higher pelvic tilt during stance on the affected leg than the anterior cohort at 6-weeks (p=0.033). Affected leg ipsilateral trunk lean during stance was higher in the lateral group at 6-weeks (p=0.006) and 12-weeks (p=0.037) compared to the other cohorts. The anterior and posterior groups demonstrated an increased external rotation moment at 6-weeks (p=0.001) and 12-weeks (p=0.005) compared to the lateral group. Discussion. Although temporal parameters were similar across all groups, some differences in gait kinematics and kinetics exist following THA using different surgical approaches. However, the clinical relevance based on the small magnitude of the differences remains in question

Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of surgical approach on gait kinetics and kinematics. The purpose of this study was to determine the impact of surgical approach for THA on quantitative gait analysis. Thirty patients undergoing THA for primary osteoarthritis of the hip were assigned to one of three surgical approaches (10 anterior, 10 posterior, and 10 lateral). A single surgeon performed each individual approach. Each patient received standardised implants at the time of surgery (cementless stem and acetabular component, cobalt chrome femoral head, highly cross-linked liner). Patients underwent 3D gait analysis pre-operatively, and at 6- and 12-weeks following the procedure. At each time point, temporal gait parameters, kinetics, and kinematics were compared. Statistical analysis was performed using one-way analysis of variance. All three groups were similar with respect to age (p=0.27), body mass index (p=0.16), and the Charlson Comorbidity Index (p=0.66). Temporal parameters including step length, stride length, gait velocity, and percent stance and swing phase were similar between the groups at all time points. The lateral cohort had higher pelvic tilt during stance on the affected leg than the anterior cohort at 6-weeks (p=0.033). Affected leg ipsilateral trunk lean during stance was higher in the lateral group at 6-weeks (p=0.006) and 12-weeks (p=0.037) compared to the other cohorts. The anterior and posterior groups demonstrated an increased external rotation moment at 6-weeks (p=0.001) and 12-weeks (p=0.005) compared to the lateral group. Although temporal parameters were similar across all groups, some differences in gait kinematics and kinetics exist following THA using different surgical approaches. However, the clinical relevance based on the small magnitude of the differences remains in question

Aims

Femoroacetabular impingement (FAI) has been highlighted and well documented primarily in Western countries and there are few large studies focused on FAI-related morphological assessment in Asian patients. We chose to investigate this subject.

Introduction. Dislocation is one of the most important complications after primary total hip replacement (THR). The low incidence of this finding makes it difficult to analyse the possible risk factors. The surgical technique can also influence this rate through cup position or an adequate reconstruction of the hip. We assessed the demographic data and radiological reconstruction of the hip related to the appearance of dislocation after primary THR. Material and Methods. 1414 uncemented THRs were recorded from our Local Joint Registry. The mean age of the patients was 60.1 years old (range, 14 to 95), and the mean weight was 73.3 kg (42 to 121). There were 733 men and 974 patients were classified with an activity level of 4 or 5 according to Devane. The most frequent diagnosis was primary osteoarthritis, 795 hips, followed by avascular necrosis 207 hips. An alumina-on-alumina THR was implanted in 703 hips and a metal-on-polyethylene THR in 711 hips. A femoral head size of 28 mm was used in 708 hips and 32 mm in 704. Radiological cup position was assessed using the acetabular abduction angle, the height of the center of the hip, and the horizontal distance of the cup. Cup anteversion was measured according to Widmer and the reconstruction of the center of rotation of the hip according to Ranawat. The radiographic reconstruction of the abductor mechanism was measured using two variables: the lever arm and the height of the greater trochanter. Results. There were 38 dislocations (2.6%) and 11 hips were revised for recurrent instability (0.8%). The probability of not having a dislocation at 20 years was 97.3%. 22 hips that had dislocated were within a box for a cup position of a version between 10º to 25º and an acetabular abduction angle between 35º to 55º (p<0.001). The probability of not having a dislocation at 20 years was 98.48% for the cups within the box and 93.9% for cups outside the box (p<0.001, Log Rank test). 21 hips that had dislocated were within a box for a height of the greater trochanter between −2 mm to 5 mm and a lever arm between 56 to 64 mm (p<0.001). The probability of not having a dislocation at 20 years was 98.33% for the hips within the box and 94.6% for hips outside the box (p<0.001, Log Rank test). Adjusted Cox regression analysis showed that alumina-on alumina THR tended to dislocate less than metal-on-polyethylene THRs (p=0.061, Hazard Ratio: 2.238, Confidence Interval 95% 0.964–5.195), and hips outside the box evaluated for cup position and outside the lever arm and height of the greater trochanter box) had a higher risk for dislocation (p<0.001, HR: 3.418, CI 95% 1.784–6.549, and, p<0.001, HR:2.613, CI 95% 1.357–5.032, respectively). Conclusions. A proper reconstruction of the hip is essential to decrease the risk for dislocation after primary THR. The choice of the bearing surface may affect this risk. The weakness of the abductor muscles of the hip may be one of the most important causes for dislocation

Puropose. Three-dimensional (3D) templating based on computed tomography (CT) in total hip arthroplasty improves the accuracy of implant size. However, even when using 3D-CT preoperative planning, getting the concordance rate between planned and actual sizes to reach 100% is not easy. To increase the concordance rate, it is important to analyze the causes of mismatch; however, no such studies have been reported. This study had the following two purposes: to clarify the concordance rate in implant size between 3D-CT preoperative planning and actual size; and to analyze risk factors for mismatch. Materials and Methods. A single surgeon performed 149 THAs using Trident Cup and Centpillar Stem (Stryker) with CT-based navigation between September 2008 and August 2011. Minimal follow-up was 2 years. Patients with incomplete postoperative CT were excluded from this study. Based on these criteria, the study examined 124 hips in 111 patients (mean age, 60 years, mean BMI 23.2 kg/m2). The preoperative diagnosis was primary osteoarthritis in 8 hips, secondary osteoarthritis in 102 hips, osteonecrosis in 9 hips, rapidly destructive coxopathy in 4 hips and rheumatoid arthritis in 1 hip. We compared cup and stem sizes between preoperative planning and intraoperatively used components. Radiological evaluations were cortical index and canal flare index on preoperative X-rays. We evaluated preoperative planning and postoperative components for cup orientation, cup position, and stem alignment (anteversion, flexion and varus angle) on the CT-navigation system. Fixation of the stem was evaluated by X-ray radiography at 2 years postoperatively according to Engh's criteria. Statistical analysis was performed with the Mann-Whitney U test, and values of P<0.05 were considered statistically significant. Results and Discussion. The concordance rate in cup size between preoperative planning and used implants was 94.4% (117/124 hips) (CS group). A one-size larger cup was used in 4 hips (CO group), and a one-size smaller cup was implanted in 3 hips (CU group). No significant difference was seen between the CS group and the CO or CU groups in change of cup orientation and cup position from planning (P>0.05) (Table 1). The concordance rate of stem size between preoperative planning and used stem was 85.5% (106/124 hips) (SS group). A one-size larger stem than the plan was used in two hips (SO group), and a one-size smaller stem than the plan was implanted in 16 hips (SU group). Significant differences were seen between the SU and SS groups in flexion angle, varus angle, and canal flare index (P<0.05, Table 2). Extension or varus of the stem, or an increase in canal flare index, were risk factors for the used stem size being smaller than planned. On the latest follow-up X-rays, all 124 hips showed bone ingrown stability of the implants. Conclusion. The accuracy of implant size selection was 94.4% and 85.5% for the cup and stem, respectively. No factors associated with cup size mismatch were identified. Flexion angle, varus angle, and canal flare index were associated with stem size mismatch between preoperative planning and the actual used size

Introduction. Female gender, old age (men >60y and women > 55y), severe acetabular dysplasia, poor proximal femoral bone geometry, large (>1cm) femoral head cysts, limb-length discrepancy (> 2cm) and small prosthetic head size (less than 50mm for men and less than 46mm for women) are risk factors for hip resurfacing arthroplasty (HRA). Purpose. To present clinical and radiographic results of HRA in patients having risk factors. Patients and methods: A total of 39 HRA was inserted in 33 patients (11 men and 22 women). Birmingham hip resurfacing (Smith & Nephew, UK) was used in 9 hips and Adept (Finsbury, UK) was used in 30 hips. Among the 30 hips inserted Adept, 11 cups were fixed with rim screws. The mean age of the patients at the time of operation was 52 years. The mean weight and height of the male and female patients were 70.4kg and 167cm, 58.5kg and 154.4cm, respectively. The median head size of the male and female patients was 50mm and 42mm, respectively. Preoperative diagnosis was primary osteoarthritis in 6 hips and secondary osteoarthritis due to aceatbular dysplasia (DDH) in 33 hips. Risk factors of HRA were listed for each patient. The Harris hip score and visual analogue pain scale (VAS) were measures of clinical outcome. Radiographic review was performed retrospectively. MRI and CT images were acquired in 29 hips and 2 hips, respectively, at a mean of 4.8 years after HRA to find periprosthetic soft tissue abnormality such as a psedotumor. Kaplan-Meier method was used to calculate implant survivorship. Results. Two hips had no risk factor, whereas 37 hips had at least one risk factor. Risk factors were listed as follows: female gender in 27, old age in nine, severe acetabular dysplasia in 25, poor proximal femoral bone geometry in 11, head cysts in 13, limb-length discrepancy in three and small head size in 21. There were two revisions in two men. One hip was revised because of acute infection. The patient had a risk factor (old age). Another hip was revised because of cup loosening. The patient had two risk factors (severe acetabular dysplasia and small head size). The mean follow-up period for unrevised hips was 5 years (range, 2 to 8 years). The Harris hip score improved from 47.3 points preoperatively to 96.5 points at the latest follow-up (p<0.001). VAS improved from 65 preoperatively to 5 at the latest follow-up (p<0.001). Using revision for any reason as the endpoint, the Kaplan-Meier survivorship was 94.9% at 5years. No implant was loose at the latest radiographic examination. MRI and CT of the hip revealed no pseudotumor. Discussion. In this series, only two patients had no risk factor for HRA. Although majority of our patients were women with acetabular dysplasia and small head size, clinical and radiographic results of HRA were good up to five years (Figs 1 and 2: pre- and post-operative X-ray of 49y women having five risk factors). Conclusion. Clinical and radiographic results of HRA were good in patients who have risk factors

We present the results of 62 consecutive acetabular revisions using impaction bone grafting and a cemented polyethylene acetabular component in 58 patients (13 men and 45 women) after a mean follow-up of 27 years (25 to 30). All patients were prospectively followed. The mean age at revision was 59.2 years (23 to 82).

We performed Kaplan–Meier (KM) analysis and also a Competing Risk (CR) analysis because with long-term follow-up, the presence of a competing event (i.e. death) prevents the occurrence of the endpoint of re-revision.

A total of 48 patients (52 hips) had died or had been re-revised at final review in March 2011. None of the deaths were related to the surgery. The mean Harris hip score of the ten surviving hips in ten patients was 76 points (45 to 99).

The KM survivorship at 25 years for the endpoint ‘re-revision for any reason’ was 58.0% (95% confidence interval (CI) 38 to 73) and for ‘re-revision for aseptic loosening’ 72.1% (95% CI 51 to 85). With the CR analysis we calculated the KM analysis overestimates the failure rate with respectively 74% and 93% for these endpoints. The current study shows that acetabular impaction bone grafting revisions provide good clinical results at over 25 years.

Cite this article: Bone Joint J 2015;97-B:1338–44.

We examined the risk of thrombotic and major bleeding events in patients undergoing total hip and knee replacement (THR and TKR) treated with thromboprophylaxis, using nationwide population-based databases. We identified 83 756 primary procedures performed between 1997 and 2011. The outcomes were symptomatic venous thromboembolism (VTE), myocardial infarction (MI), stroke, death and major bleeding requiring hospitalisation within 90 days of surgery.

A total of 1114 (1.3%) and 483 (0.6%) patients experienced VTE and bleeding, respectively. The annual risk of VTE varied between 0.9% and 1.6%, and of bleeding between 0.4% and 0.8%. The risk of VTE and bleeding was unchanged over a 15-year period. A total of 0.7% of patients died within 90 days, with a decrease from 1% in 1997 to 0.6% in 2011 (p < 0.001). A high level of comorbidity and general anaesthesia were strong risk factors for both VTE and bleeding, with no difference between THR and TKR patients. The risk of both MI and stroke was 0.5%, which remained unchanged during the study period.

In this cohort study of patients undergoing THR and TKR patients in routine clinical practice, approximately 3% experienced VTE, MI, stroke or bleeding. These risks did not decline during the 15-year study period, but the risk of dying fell substantially.

Cite this article: Bone Joint J 2014;96-B:479–85.

Patients with acetabular dysplasia commonly undergo peri-acetabular osteotomy after skeletal maturity to reduce the risk of the late development of osteoarthritis. Several studies have suggested that deformity of the femoral head influences the long-term outcome. We radiologically examined 224 hips in 112 patients with acetabular dysplasia and early-stage osteoarthritis. There were 103 women and nine men with a mean age of 37.6 years (18 to 49). A total of 201 hips were placed in the acetabular dysplasia group and 23 in a normal group. The centre–edge angle and acetabular head index were significantly smaller (both p < 0.001), and the acetabular angle, acetabular roof angle and roundness index were significantly greater in the acetabular dysplasia group than those in the normal group (all p < 0.001). There were significant correlations between the roundness index and other parameters. Femoral head shape may be influenced by the severity of the acetabular dysplasia.

Cite this article: Bone Joint J 2013;95-B:1192–6.

Progressive retroversion of a cemented stem is predictive of early loosening and failure. We assessed the relationship between direct post-operative stem anteversion, measured with CT, and the resulting rotational stability, measured with repeated radiostereometric analysis over ten years. The study comprised 60 cemented total hip replacements using one of two types of matt collared stem with a rounded cross-section. The patients were divided into three groups depending on their measured post-operative anteversion (< 10°, 10° to 25°, >  25°). There was a strong correlation between direct post-operative anteversion and later posterior rotation. At one year the < 10° group showed significantly more progressive retroversion together with distal migration, and this persisted to the ten-year follow-up. In the < 10° group four of ten stems (40%) had been revised at ten years, and an additional two stems (20%) were radiologically loose. In the ‘normal’ (10° to 25°) anteversion group there was one revised (3%) and one loose stem (3%) of a total of 30 stems, and in the > 25° group one stem (5%) was revised and another loose (5%) out of 20 stems. This poor outcome is partly dependent on the design of this prosthesis, but the results strongly suggest that the initial rotational position of cemented stems during surgery affects the subsequent progressive retroversion, subsidence and eventual loosening. The degree of retroversion may be sensitive to prosthetic design and stem size, but < 10° of anteversion appears deleterious to the long-term outcome for cemented hip prosthetic stems.

Cite this article: Bone Joint J 2013;95-B:23–30.

In a double-blinded randomised controlled trial, 83 patients with primary osteoarthritis of the hip received either a ceramic-on-metal (CoM) or metal-on-metal (MoM) total hip replacement (THR). The implants differed only in the bearing surfaces used. The serum levels of cobalt and chromium and functional outcome scores were compared pre-operatively and at six and 12 months post-operatively. Data were available for 41 CoM and 36 MoM THRs (four patients were lost to follow-up, two received incorrect implants). The baseline characteristics of both cohorts were similar. Femoral head size measured 36 mm in all but two patients who had 28 mm heads. The mean serum cobalt and chromium levels increased in both groups, with no difference noted between groups at six months (cobalt p = 0.67, chromium p = 0.87) and 12 months (cobalt p = 0.76, chromium p = 0.76) post-operatively. Similarly, the mean Oxford hip scores, Western Ontario and McMaster Universities Osteoarthritis index and University of California, Los Angeles activity scores showed comparable improvement at 12 months. Our findings indicate that CoM and MoM couplings are associated with an equivalent increase in serum cobalt and chromium levels, and comparable functional outcome scores at six and 12-months follow-up.