Results of metal-on-metal hip resurfacing in patients 40 years old and younger

The prevalence of total hip arthroplasty in young patients is small but increasing. We analyzed the results of metal-on-metal hip resurfacing (MMHR) in patients aged 40 years or less. In total 74 operations were performed on 64 patients. Mean age at operation was 33.2 years. HHS averaged 92.3 points at latest follow-up, mean UCLA activity was 8.2. Patients with comorbidity evinced lower scores in HHS, in UCLA activity and in quality of life than patients without comorbidities. Eight revisions (10.8 %) were performed, of which seven due to adverse reaction to metal debris. Seven-year survival was 90.5 %. The functional outcome of hip resurfacing in this cohort was excellent, but overall survival was unsatisfactory. Further analysis is required to verify the role of hip resurfacing among young and active patients.     

Higher Prevalence of Mixed or Solid Pseudotumors in Metal-on-Polyethylene Total Hip Arthroplasty Compared With Metal-on-Metal Total Hip Arthroplasty and Resurfacing Hip Arthroplasty

Background

Pseudotumors are a common finding in metal-on-metal (MoM) total hip arthroplasty (THA) and resurfacing hip arthroplasty (RHA). However, information on pseudotumors in metal-on-polyethylene (MoP) THA is limited.

Bearing exchange in the management of pseudotumours

Introduction

Soft tissue reactions following metal-on-metal (MoM) arthroplasty of the hip have been under considerable discussion. These reactions are seen following both hip resurfacing and MoM total hip arthroplasty (THA). The phenomenon may arise owing to shedding of metal particles in high wear states, hypersensitivity with normal metal wear rates or a combination of the two.

Methods

Three patients were identified who had developed a soft tissue reaction (pseudotumour) following MoM hip resurfacing procedures. The prostheses were revised to ceramic-on-ceramic (CoC) THA with only minimal debridement of the pseudotumour. Pre and postoperative magnetic resonance imaging was performed to assess the size of the lesions.

Results

Progressive and satisfactory resolution of the associated pseudotumours was identified following revision of the prostheses to CoC THA.

Conclusions

In the early stages of pseudotumour formation following MoM hip resurfacing, this potentially devastating condition can be managed adequately with revision to a CoC bearing THA with minimal soft tissue excision.     

(iv) Metal-on-metal hip resurfacing

The management of an arthritic hip in young active patients represents a challenge to the treating orthopaedic surgeon. Results of the conventional hip arthroplasty in male patients under 55 have been shown to approach 70% survivorship at 10 years.¹ Hip resurfacing has many theoretical advantages including bone preservation, reduced risk of dislocation and increased range of movement that can benefit this particular group of patients. The results of early hip resurfacing prototypes did not meet expectations and failures were seen early on as a result of cup loosening and femoral collapse. Recently, hip resurfacing has been reintroduced with improved design, engineering and metallurgy. The early clinical results of the new Metal-on-Metal (MoM) resurfacing prostheses are encouraging. In its new design with hard MoM bearing surfaces, hip resurfacing can provide a valuable alternative in the armamentarium of the hip surgeon.     

Femoral head resurfacing in the treatment of osteonecrosis: 3 to 5-year follow-up

We reviewed the clinical and radiological results of 32-cemented femoral head resurfacing arthroplasty, performed by a single surgeon in 25 patients with femoral head osteonecrosis at a mean age of 36.2 years. All patients received a cemented conserve (Wright Medical Technology Inc., Arlington, TN, USA) femoral hemiresurfacing arthroplasty. Data were complete on 16 patients with 21 hips at a mean follow-up period of 50.8 months. Five patients had bilateral procedures. The Harris hip score, and the Merle d’Aubigné score improved significantly from 54.7 to 72.3 (P = 0.0001), and from 12.1 to 13.9 (P = 0.01), respectively. Seven hips had undergone revision to total hip arthroplasty at the time of follow-up while one hip is scheduled for revision surgery, representing a 38% failure rate. When clinical failure is defined as a Harris Hip Score of less than 70 at follow-up, clinical failure was 81% at 4.25 years.     

Narrowing of the neck in resurfacing arthroplasty of the hip: a radiological study

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 degrees (80 degrees to 160 degrees ). 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.     

Do the Potential Benefits of Metal-on-Metal Hip Resurfacing Justify the Increased Cost and Risk of Complications?

Background  

Metal-on-metal hip resurfacing arthroplasty (MoM HRA) may offer potential advantages over total hip arthroplasty (THA) for certain patients with advanced osteoarthritis of the hip. However, the cost effectiveness of MoM HRA compared with THA is unclear.     

Accuracy of a computer-assisted navigation system in resurfacing hip arthroplasty

We developed a method to assess the accuracy of an image-free resurfacing hip arthroplasty navigation system in a proximal femur with normal and abnormal anatomy. A phantom lower limb allowed deformation in varus/valgus and ante-retroversion. At specific points during the simulated surgical procedure, information was compared between a digital caliper and the computer navigation system angular measurements. Repeated serial tests were undertaken. In the setting of normal anatomical alignment of the proximal femur, the mean error of the system characterised as the difference between the measured computer navigation and caliper angles was 0.6 degrees in the frontal plane and 3.4 degrees in the lateral plane. In the setting of abnormal anatomical alignment, the mean error was 0.4 degrees in the frontal plane and 2.1 degrees in the lateral plane. This is the first study designed to assess the accuracy of a femoral navigation system for resurfacing hip arthroplasty in normal settings and in the presence of angular deformity. The study demonstrates satisfactory in-vitro accuracy.     

Update Metall-Metall-Gleitpaarungen

Increasing data are available describing risk factors for the development of local and systemic adverse events following operations using metal-on-metal (MoM) hip implants. The prevalence and clinical relevance of metal-associated problems are, however, still under debate. They can be influenced by type and position of implant as well as patient-specific factors. Patients with small MoM heads (maximum diameter 32 mm) and subgroups of resurfacing arthroplasty can achieve good long-term survival. The use of large head MoM implants (diameters greater than 36 mm), however, is currently not advised due to the unsatisfactory results.     

A multinational assessment of metal-on-metal bearings in hip replacement

There is emerging evidence that many metal-on-metal (MoM) bearings, when used with large femoral heads in conventional hip replacement and some resurfacing prostheses, are associated with increased rates of revision arthroplasty. Registries are the main sources of data on MoM prostheses. At the recent International Consortium of Orthopaedic Registries (ICOR) meeting, data were presented from the Australian, England and Wales, and New Zealand registries. All registries reported an increased rate of revision for large femoral head MoM prostheses when prostheses were aggregated compared with the aggregated data of hip prostheses with other bearing surfaces. There was also evidence, however, that the outcome varied, depending on the type of prostheses used, in both large femoral head MoM conventional hip replacement as well as resurfacing hip replacement.The relevance of the recent isolated case reports on systemic metal toxicity was also discussed at the ICOR meeting. Although systemic metal toxicity appears to be a rare occurrence, there is a need to undertake appropriately designed studies to define the true prevalence of this phenomenon. There may be advantages in nesting these studies within registries. The ICOR meeting highlighted the implications of the MoM experience for the orthopaedic industry, regulators, and surgeons.     

A five-year radiostereometric follow-up of the Birmingham Hip Resurfacing arthroplasty

The early designs of hip resurfacing implants suffered high rates of early failure, making it impossible to obtain valuable mid-term radiostereophotogrammetric (RSA) results. The metal-on-metal Birmingham Hip Resurfacing arthroplasty has shown promising mid-term results and we present here the first mid-term RSA analysis of a hip resurfacing implant. The analysis was performed in 19 hips at five years post-operatively. The mean acetabular component translation and rotation, and femoral component translation were compared with the previous RSA measurements at two and six months, and one and two years. There was no statistical significance (t-test, p < or = 0.05) between these consecutive movements, indicating the mid-term stability of the implant.     

Results of metal-on-metal hybrid hip resurfacing for Crowe type-I and II developmental dysplasia

BACKGROUND: Modern hip resurfacing implants may increase stability and preserve more bone than conventional total hip arthroplasty. The purpose of this retrospective study was to analyze the mid-term results in a consecutive series of middle-aged patients with developmental dysplasia of the hip treated with hybrid resurfacing joint arthroplasty. METHODS: Metal-on-metal hip resurfacing was performed in fifty-one patients (fifty-nine hips), forty-two of whom were female and nine of whom were male. The average age at the time of surgery was 43.7 years. Radiographic and clinical data were collected at six weeks, at three months, and at yearly follow-up visits. Seven hips had Crowe type-II developmental dysplasia of the hip and fifty-two had type-I. RESULTS: The follow-up period ranged from 4.2 to 9.5 years (average, 6.0 years). Initial stability was achieved in all but three hips. The clinical outcomes, as rated with the University of California at Los Angeles (UCLA) hip score, improved significantly compared with the preoperative ratings. On the average, the pain rating improved from 3.2 to 9.3 points; the score for walking, from 6.0 to 9.7 points; the score for function, from 5.7 to 9.6 points; and the score for activity, from 4.6 to 7.3 points (all p = 0.0001). The mean Short Form-12 (SF-12) mental score increased from 46.6 to 53.5 points, and the mean SF-12 physical score increased from 31.7 to 51.4 points (both p < 0.0001). The mean postoperative Harris hip score was 92.5 points. On the average, the range of flexion improved from 106 degrees to 129.6 degrees ; the abduction-adduction arc, from 41.9 degrees to 76.9 degrees ; and the rotation arc in extension, from 32.1 degrees to 84.8 degrees (all p = 0.0001). Four patients delivered a total of six healthy babies since the time of implantation of the prosthesis. Radiographic analysis showed a decrease in the mean body weight lever arm from 118.5 mm preoperatively to 103.9 mm postoperatively (p = 0.007). There were five femoral failures requiring conversion to a total hip arthroplasty. One hip showed a radiolucency around the metaphyseal femoral stem. There were no complete acetabular radiolucencies, and all sockets remained well fixed. CONCLUSIONS: The mid-term results of metal-on-metal resurfacing in patients with Crowe type-I or II developmental dysplasia of the hip were disappointing with respect to the durability of the femoral component. However, the fixation of the porous-coated acetabular components without adjuvant fixation was excellent despite incomplete lateral acetabular coverage of the socket. More rigorous patient selection and especially meticulous bone preparation are essential to minimize femoral neck fractures and loosening after this procedure.     

金属对金属髋关节表面置换术的短期随访研究

目的探讨金属对金属(MOM)混合固定型髋关节表面置换术(HRA)的近期疗效,分析手术技术要点。方法 2004年10月至2008年6月,对52例(58髋)股骨头缺血性坏死、骨关节炎、髋关节发育不良、强直性脊柱炎患者行MOM-HRA。其中男32例,女20例;年龄16～65岁,平均42.6岁。手术方法按照K.De.Smet标准方法进行,术后对Harris评分、关节活动度和X线片进行随访。结果失访7例(8髋),45例(50髋)获得随访,随访时间平均22个月(12～54个月)。术前平均Harris评分(37.0±1.2)分,术后22个月平均(93.0±1.0)分;术前屈髋度平均(25.3±1.6)°,术后22个月平均(105.0±1.8)°;术前外展度平均(18.8±0.8)°,术后22个月平均(40.6±1.0)°。评价:46髋优,3髋良,1髋差。无股骨颈骨折,无松动,无脱位,无感染,无翻修,1例异位骨化BrookerⅢ型。结论 HRA具有保留股骨头骨量、术后关节活动度恢复快、近期结果好等优点,对于获得优良的术后结果,严格的患者选择和精确的手术技术至关重要。     

Primary total hip replacement versus hip resurfacing - hospital considerations

Multiple factors regarding surgical procedures and patient selection affect hospital staffing needs as well as hospital revenues. In order to better understand the potential impact on hospitals that hip arthroplasty device selection (standard total hip arthroplasty vs. resurfacing) creates, a review of all primary hip arthroplasties performed at one institution was designed to identify factors that impacted hospital staffing needs and revenue generation. All primary hip arthroplasties undertaken over three fiscal years (2008 to 2010) were reviewed, utilizing only hospital business office data and medical records data that had been previously extracted prior for billing purposes. Analysis confirmed differing demographics for two hip arthroplasty populations, with the resurfacing patients (compared to the conventional total hip arthroplasty population) consisting of younger patients (mean age, 50 vs. 61 years), who were more often male (75% vs. 45%), were more likely to have osteoarthritis as their primary diagnosis (83 vs. 67%) and were more often covered by managed care or commercial insurance (83 vs. 34%). They also had shorter hospital stays (mean length of stay, 2.3 vs. 4.1 days) and consequently provided a more favorable financial revenue stream to the hospital on a per patient basis. Several trends appeared during the study periods. There was a steady increase in all procedures in all groups except for the resurfacings, which decreased 26% in males and 53% in females between 2009 and 2010. Differences were observed in the demographics of patients presenting for resurfacing, compared to those presenting for conventional total hip arthroplasty. In addition to the revenue stream considerations, institutions undertaking a resurfacing program must commit the resources and planning in order to rehabilitate these patients more expeditiously than is usually required with conventional hip arthroplasty patients.     

Surface arthroplasty in young patients with hip arthritis secondary to childhood disorders

Legg-Calvé-Perthes disease (LCP) and slipped capital femoral epiphysis (SCFE) may result in alterations of the proximal femoral morphology, leading to the development of hip osteoarthritis as a young adult. Hip surface arthroplasty presents special technical challenges in these patients because of the abnormal anatomy of the head and neck. The authors reviewed the radiographic and clinical results of patients with a history of LCP or SCFE who underwent hip resurfacing between 1996 and 2002. Despite the challenges in performing hip resurfacing in this patient population and the inability to completely normalize hip anatomy, biomechanics, and leg length discrepancy, the results to date have been encouraging.     

Previous Bernese periacetabular osteotomy does not compromise the results of total hip arthroplasty

It is not known if a previous periacetabular osteotomy poses technical difficulties and may increase the incidence of complications after total hip arthroplasty. The records of 41 patients who had THA after periacetabular osteotomy were evaluated. Followup averaged 6.9 years (range, 2-14 years). The average interval from osteotomy to total hip arthroplasty was 6.3 years (range, 4 months-14 years). Total hip arthroplasty provided significant relief of pain and improvement in function for all the patients. The acetabulum was judged to be retroverted in 23 patients and special attention to component positioning was needed. An abnormal proximal femoral anatomy secondary to previous intertrochanteric osteotomy or underlying dysplasia, or trochanteric overgrowth necessitated the use of trochanteric osteotomy for exposure in 24 patients. There were an acceptable number of complications and two revisions in the series. Aseptic loosening of the femoral component in one patient (one hip) and acetabular component in another patient (one hip) were the reasons for the two revisions. Total hip arthroplasty with technical consideration and careful evaluation of the acetabular version and relocated teardrop can be done safely in patients with a previous periacetabular osteotomy and should provide excellent results.     

Removal of acetabular bone in resurfacing arthroplasty of the hip: a comparison with hybrid total hip arthroplasty

Resurfacing arthroplasty of the hip is being performed more frequently in the United Kingdom. The majority of these patients are younger than 55 years of age, and in this group the key benefits include conservation of femoral bone stock and the potential reduction in the rate of dislocation afforded by the larger resurfacing head. Early aseptic loosening is well recognised in patients younger than 55 years of age, and proponents of resurfacing believe that the improved wear characteristics of the metal-on-metal bearing may improve the long-term survival of this implant. There has been some concern, however, that resurfacing may not be conservative of acetabular bone.We compared a series of 33 consecutive patients who had a hybrid total hip arthroplasty with an uncemented acetabular component and a cemented femoral implant, with 35 patients undergoing a Birmingham hip resurfacing arthroplasty. We compared the diameter of the implanted acetabulum in both groups and, because they were not directly comparable, we corrected for patient size by measuring the diameter of the contralateral femoral head. The data were analysed using unpaired t-tests and analysis of covariance.There was a significantly larger acetabulum in the Birmingham arthroplasty group (mean diameter 56.6 mm vs 52.0 mm; p < 0.001). However, this group had a significantly larger femoral head diameter on the contralateral side (p = 0.03). Analysis of covariance revealed a significant difference between the mean size of the acetabular component implanted in the two operations. The greatest difference in the size of acetabulum was in those patients with a larger diameter of the femoral head. This study shows that more bone is removed from the acetabulum in hip resurfacing than during hybrid total hip arthroplasty, a difference which is most marked in larger patients.