Large-diameter Head Research Articles

Failure rates of stemmed metal-on-metal hip replacements: analysis of data from the National Joint Registry of England and Wales

Total hip replacement (THR) is extremely common. Some prostheses fail, particularly in younger patients, and need to be revised, most commonly for loosening secondary to wear or dislocation. Surgeons have tried to address these problems by implanting large diameter metal-on-metal bearing surfaces. Our aim was to assess if metal-on-metal bearing surfaces lead to increased implant survival compared with other bearing surfaces in stemmed THR and, additionally, if larger head sizes result in improved implant survival. We analysed the National Joint Registry of England and Wales for primary hip replacements (402,051, of which 31,171 were stemmed metal-on-metal) undertaken between 2003 and 2011. Our analysis was with a multivariable flexible parametric survival model to estimate the covariate-adjusted cumulative incidence of revision adjusting for the competing risk of death. Metal-on-metal THR failed at high rates. Failure was related to head size, with larger heads failing earlier (3·2% cumulative incidence of revision [95% CI 2·5-4·1] for 28 mm and 5·1% [4·2-6·2] for 52 mm head at 5 years in men aged 60 years). 5 year revision rates in younger women were 6·1% (5·2-7·2) for 46 mm metal-on-metal compared with 1·6% (1·3-2·1) for 28 mm metal-on-polyethylene. By contrast, for ceramic-on-ceramic articulations larger head sizes were associated with improved survival (5 year revision rate of 3·3% [2·6-4·1] with 28 mm and 2·0% [1·5-2·7] with 40 mm for men aged 60 years). Metal-on-metal stemmed articulations give poor implant survival compared with other options and should not be implanted. All patients with these bearings should be carefully monitored, particularly young women implanted with large diameter heads. Since large diameter ceramic-on-ceramic bearings seem to do well we support their continued use. National Joint Registry of England and Wales.

Chinese Experience With Metal-on-Metal Hip Resurfacing

The aim of this study was to study the actual clinical and laboratory results of metal-on-metal resurfacing hip arthroplasties by comparing with other implants. A total of 127 cases were operated on at the Department of Orthopaedics of Wuhan Union Hospital from 2005 to 2011. An important cause of failure is the fracture of the femoral neck. The chromium and cobalt levels of resurfacing hip arthroplasty and large-diameter head total hip arthroplasty (THA) are higher than those of a conventional metal-on-polyethylene total hip arthroplasty. There was a high ion level associated with an abduction angle of more than 45° and repetitive extreme hip motion in the 3 revision cases. The findings of this study are novel and quite controversial with that of the previously published literature.

Cobalt and Chromium Ion Release After Large-Diameter Metal-on-Metal Total Hip Arthroplasty

Seventy-five patients underwent unilateral metal-on-metal total hip arthroplasty using a large-diameter head. Serum levels of cobalt and chromium were determined. Significant increases in both cobalt and chromium were observed at 3 months (cobalt, 1.4 μg/L; chromium, 1.4 μg/L) compared with preoperative values (P < .001). At 1 year, the median cobalt and chromium levels were 2.3 and 2.1 μg/L, respectively, and the levels had increased significantly compared with 3 months (P < .001). There were no significant differences between levels of either metal at 1 or 2 years (cobalt, 2.3 μg/L; chromium, 1.6 μg/L). Pseudotumor occurred in 2 hips. Patients with large-diameter metal-on-metal total hip arthroplasty had higher circulating metal ion levels at 3 months and 1 year, with no additional significant increases at 2 years.

Association between seed yield and some morphological characteristics in sunflower

Objective of this study was to determine the divergence and association between seed yield and three morphological characteristics that are very important in sunflower breeding (plant height, head diameter and days to flowering) in order to identify the most valuable trait for seed yield improvement. Forty new hybrid combinations were evaluated. Cluster analysis was used to determine genetic diversity in new hybrid combinations by classifying genotypes based on average values of the studied characteristics. Genotypes were classified into three homogenous groups and six individuals. Pearson's correlation coefficients were used to examine association between the studied characteristics, among which days to flowering showed negative correlation while plant height and head diameter showed positive correlation with seed yield, on both genotypic and phenotypic levels. Our study showed that there is genetic variability among new hybrids and bearing in mind that hybrids should be grown in different agro-ecological environments, our attention should be focused on developing inbred lines with lower stem resistant to lodging, larger head diameter and earlier flowering.

Reliability of Ceramic Components

As we enter the 4th decade of use, ceramic-on-ceramic total hip arthroplasty remains a viable bearing surface for young and active patients requiring hip replacement. Improvements in manufacturing and component design have continually improved reliability and safety of these implants. Furthermore, the latest iteration of ceramics, which allows for larger head diameters and more head and liner combinations, has further leveled the playing field when it comes to hard-on-hard bearing surfaces. Finally, with recent reports of early failures and unexplained idiosyncratic reactions in patients with metal-on-metal arthroplasty, we suggest that surgeons faced with young and active patients should consider ceramics, with its excellent wear characteristics and biocompatibility, as the only safe hard-on-hard bearing surface suitable for implantation.

Perspectives in Managing an Implant Recall: Revision of 94 Durom Metasul Acetabular Components

The Metasul LDH Large Diameter Head with Durom Acetabular Component (Zimmer, Warsaw, Indiana) was launched in Europe in 20031 and was approved by the United States Food and Drug Administration (FDA) in April 20062. The Durom acetabular component was designed as a monoblock, truncated hemispherical cup with a 165° arc, and had performed well in the Swedish Arthroplasty Registry and in early European studies3,4. The senior author (M.A.M.), a fellowship-trained surgeon specializing in adult reconstruction who had more than twenty years’ experience with total hip arthroplasty, performed approximately 400 primary total hip arthroplasties annually during the past five years and 100 to 150 annually during the preceding years. Prior to October 2006, he utilized the Trabecular Metal Modular Acetabular System (Zimmer) with good success. Utilization of the Durom cup began in October 2006 because of the good results that had been reported internationally and the purported benefits of increased range of hip motion, enhanced stability, and greater durability. The senior author implanted 297 Durom acetabular cups during the subsequent two years. All procedures were performed at a large community hospital with a company representative present in the operating room. None of the patients was part of a clinical trial, and the surgeon had no current industry ties. All cups were inserted according to the manufacturer's instructions. The learning curve was rapid, and no obvious intraoperative complications developed. A minority of patients (seventy-six of 297, 26%) progressed slowly with therapy, reporting vague symptoms of groin discomfort, mild pain with initial weight-bearing, and difficulty with ambulation. Furthermore, several patients who had a non-Durom cup on the contralateral side reported worse performance on the side with the Durom cup. Nevertheless, there was little objective evidence to support the existence of a widespread problem. Because there were …

Cushion bearings versus large diameter head metal-on-metal bearings in total hip arthroplasty: a short-term metal ion study

Metal-on-metal total hip arthroplasty (MOM THA) has the advantage of replicating the femoral head size, but the postoperative elevation of serum metal ion levels is a cause for concern. Metal-on-polycarbonate-urethane is a new cushion bearing featuring a large diameter metal head coupled with a polycarbonate-urethane liner. The aim of this study was to assess and compare serum cobalt (Co) and chromium (Cr) levels in a group of 15 patients treated with a cushion bearing THA system (Group A) and a group of 15 patients treated with a MOM THA system (Group B) at short-term. At a mean follow-up of 27.3 months (18-35 months), in Group A the median Cr and Co serum levels were significantly lower than in Group B, measuring 0.24 μg/L (0.1-2.1 μg/L) and 0.6 μg/L (0.29-2.3 μg/L) compared to 1.3 μg/L (0.1-9 μg/L, p < 0.001) and 2.9 μg/L (0.85-13.8 μg/L, p < 0.001) respectively. All patients demonstrated an excellent clinical result, as shown by the Harris and Oxford hip scores. The cushion bearing THA studied in this paper showed clinical outcomes similar to the MOM THA bearing, with the advantage of no significant metal ion elevation in the serum. These findings warrant the continued clinical study of compliant bearing options.

Large Diameter Femoral Heads Impose Significant Alterations on the Strains Developed on Femoral Component and Bone: A Finite Element Analysis

Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost’s law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used.

Surface Replacement Conversion: Ensuring an Optimal Total Hip Replacement Outcome

Although hip resurfacing is becoming established as a treatment of hip arthritis in younger, active patients, there has been a greater failure rate in the short term when compared with traditional total hip replacement (THR). Failure modes of hip resurfacing include femoral neck fracture, osteonecrosis of the femoral head, metal hypersensitivity, component malposition leading to metal ion reactivity, and unexplained pain. It is essential to perform a proper workup of these potential failure mechanisms to correct the problem and ensure an optimal THR outcome. Acetabular component condition must be assessed at the time of conversion to THR. If the acetabular socket is well-fixed and well-positioned, a conversion to a stemmed femoral component with a matching large-diameter metal head is an easy, reproducible solution to femoral neck fracture or femoral loosening. Conversion to THR with a large diameter metal ball can also be a solution to impingement by improving the head–neck ratio. If the acetabular component is malpositioned, there can be edge-loading leading to the production of high levels of metal ion. Blood metal ions assessment can be helpful preoperatively to determine the condition of the implants; if substantially elevated, the resurfacing components are likely damaged and should be fully revised. Finally, metal hypersensitivity is a possible failure mechanism. This should be a diagnosis of exclusion, but if thought to be the culprit, the components should be fully revised to a non-metal articulation. Conversion to THR after failed hip resurfacing has been shown to have results comparable with primary THR in most cases. Performing an algorthmic workup preoperatively will help ensure an optimal THR outcome.

Residual Groin Pain at a Minimum of Two Years After Metal-on-Metal THA with a Twenty-eight-Millimeter Femoral Head, THA with a Large-Diameter Femoral Head, and Hip Resurfacing

Groin pain may persist in up to 4.3% of patients after total hip arthroplasty and up to 18% of patients one year after hip resurfacing. The incidence of this problem after total hip arthroplasty with a large-diameter femoral head is unknown. We analyzed the natural history of groin pain and its clinical consequences during the first two years after three types of hip arthroplasty. Data were collected prospectively on 279 patients. Eighty-five patients had a polyethylene sandwich metal-on-metal total hip arthroplasty with a 28-mm-diameter femoral head, 105 had hip resurfacing, and eighty-nine had a total hip arthroplasty with a large-diameter femoral head component with three other cup designs (forty-nine in this group had the same monoblock acetabular cup design as those who had hip resurfacing). At the twenty-four-month follow-up evaluation, seventy-seven patients (28%) reported at least one painful area around the hip and thirty-four patients (12.2%) had pain at more than one location. At three months, the incidence of groin discomfort was significantly increased in those who had hip resurfacing (30.5%) and in those who had total hip arthroplasty with a large-diameter femoral head (30%) compared with those who had total hip arthroplasty with a 28-mm femoral head (18.3%). This incidence decreased at two years (14.9%, 16.9%, and 12.9%, respectively). At twenty-four months postoperatively, eleven (four who had hip resurfacing, six who had total hip arthroplasty with the large-diameter head, and one who had total hip arthroplasty with the 28-mm head) of forty-one patients who had groin pain had not reported groin pain at previous follow-up evaluations. Of the forty-one patients reporting groin pain at the time of the last follow-up, twenty-three patients (56%) did not seek further evaluation or treatment, nine had revision surgery (22%), and the remaining nine patients thought the pain was substantial enough to warrant further evaluation and treatment. When the exact source of groin pain cannot be found after total hip arthroplasty, careful follow-up should be done as local reactions to metal-on-metal implants and component loosening may take time to become apparent clinically or on imaging studies.

Update - “Big-head”: The solution to the problem of hip implant dislocation?

New friction couples, initially intended to limit osteolysis risk due to debris, have enabled larger implant head diameters to be developed to resolve the problem of hip implant dislocation. The Symposium demonstrated that, whatever the configuration, increased head diameter significantly reduced the incidence of dislocation, but that none of the friction couples fulfilled the mechanical and/or biomechanical charge-book for consistently reliable use of large diameter heads. The greatest caution is therefore recommended in their implementation.

Center of Mass Compensation during Gait in Hip Arthroplasty Patients: Comparison between Large Diameter Head Total Hip Arthroplasty and Hip Resurfacing

Objective. To compare center of mass (COM) compensation in the frontal and sagittal plane during gait in patients with large diameter head total hip arthroplasty (LDH-THA) and hip resurfacing (HR). Design. Observational study. Setting. Outpatient biomechanical laboratory. Participants. Two groups of 12 patients with LDH-THA and HR recruited from a larger randomized study and 11 healthy controls. Interventions. Not applicable. Main Outcome Measures. To compare the distance between the hip prosthetic joint center (HPJC) and the COM. The ratio (RHPJC-COM) and the variability (CVHPJC-COM) were compared between groups. Hip flexor, abductor, and adductor muscle strength was also correlated between groups while radiographic measurements were correlated with the outcome measures. Results. In the frontal plane, HR shows less variability than healthy controls at push-off and toe-off and RHPJC-COM is correlated with the muscle strength ratios (FRABD) at heel contact, maximal weight acceptance, and mid stance. In the sagittal plane, LDH-THA has a higher RHPJC-COM than healthy controls at push-off, and CVHPJC-COM is significantly correlated with FRFLEX. Conclusions. One year after surgery, both groups of patients, LDH-THA and HR, demonstrate minor compensations at some specific instant of the gait cycle, in both frontal and sagittal planes. However, their locomotion pattern is similar to the healthy controls.

Range of motion of large head total hip arthroplasty is greater than 28 mm total hip arthroplasty or hip resurfacing

Background Reduced range of motion of the hip has a detrimental influence on lower limb function. Large diameter head total hip arthroplasty may theoretically have a greater potential for restoring normal hip range of motion due to greater head–neck diameter ratio, and hence provide better function compared to conventional or hip resurfacing arthroplasty. Method At minimum one year follow-up, range of motion of the operated and contra lateral hips was clinically assessed using digital photographs and bony landmarks in a clinical comparative study. We assessed if 1) large diameter head total hip arthroplasty (55 patients) restores better hip range of motion compared to 28 mm total hip arthroplasty (50 patients) or hip resurfacing (60 patients) 2) large diameter head total hip arthroplasty achieves same hip range of motion as contra lateral normal hips and 3) hip range of motion correlates with the WOMAC score. Findings The large diameter head total hip arthroplasty group had significantly greater total arcs of motion (approximately 20°), mostly due to an increase of hip flexion and external rotation, but did not reach normal hip motion. The hip range of motion showed significant correlation with the WOMAC score, especially the flexion arc. Interpretation The better hip range of motion of large diameter head total hip arthroplasty is likely due to the greater head to neck diameter ratio and hence seems to be the best option to optimize range of hip motion and improve function after hip arthroplasty.

Total hip replacement in acute displaced intracapsular proximal femoral fractures—the role of large diameter heads & their effect on dislocation rates

Total hip replacement in acute displaced intracapsular proximal femoral fractures—the role of large diameter heads & their effect on dislocation rates

Do Large Heads Enhance Stability and Restore Native Anatomy in Primary Total Hip Arthroplasty?

Dislocation remains a serious complication in hip arthroplasty. Resurfacing proponents tout anatomic femoral head restoration as an advantage over total hip arthroplasty. However, advances in bearings have expanded prosthetic head options from traditional sizes of 22, 26, 28, and 32 mm to diameters as large as 60 mm. Large heads reportedly enhance stability owing to increased range of motion before impingement and increased jump distance to subluxation. Available larger diameter material combinations include metal- or ceramic-on-highly crosslinked polyethylene and metal-on-metal, each with distinct advantages and disadvantages. We sought to determine (1) if using larger diameter heads has lowered our dislocation rate; and (2) how closely an anatomic metal-on-metal bearing with diameters to 60 mm replicates native femoral head size. We retrospectively reviewed 2020 primary arthroplasties performed with large heads (≥ 36 mm) in 1748 patients and noted dislocation incidence. In a prospective subset of 89 cases using anatomic heads, native femoral head diameter was measured intraoperatively with calipers by an independent observer and later compared with implanted size. One dislocation has occurred in 2020 hips for an incidence of 0.05%. The prosthetic head averaged 0.7 mm larger than the native head with 68 of 89 (76%) reconstructed to within ± 2 mm of native size. Larger diameter heads have contributed to lower dislocation rates and large-diameter metal-on-metal articulation can provide close anatomic restoration in primary THA.

大径骨頭を用いたMetal-on-metal THA後の血中金属イオン濃度

大径骨頭を用いたMetal-on-metal THA後の血中金属イオン濃度

Complications of Hip Arthroplasty: Editorial Comment

Total hip arthroplasty has become one of the most predictable and reproducible procedures in medicine; however, while uncommon, complications continue to occur and remain potentially devastating to both patient and surgeon alike. Therefore, as we strive to improve an already reliable surgical procedure, it has become increasingly important that these improvements target the prevention and treatment of complications in order to achieve better short- and long-term outcomes. Furthermore, as the economics of rising costs continue to drive healthcare reform to optimize outcomes while promoting efficiency, it is imperative that arthroplasty surgeons focus on minimizing complications to enhance the value of hip arthroplasty within our society and the healthcare market. Therefore, we believe the content of this symposium timely and relevant to any orthopaedic surgeon who performs hip arthroplasty today. Recently, modern surgical techniques and implant biomaterials have been developed with claims of improving outcomes, yet conflicting reports of increased and occasionally unique complications have emerged. This has created controversy and tempered enthusiasm for these new technologies, as well as advising caution for rapid acceptance and utilization. As physicians and as a profession, we are obligated to critically evaluate new techniques and technologies with strict scientific rigor and make informed treatment decisions in an evidence-based fashion. Some of the current and most relevant issues that arthroplasty surgeons are facing include hip resurfacing arthroplasty, alternative bearing surfaces and minimal incision surgical techniques. Of particular interest are the unique complications of metal-on-metal bearings and hip resurfacing that have recently followed a period of increased usage by surgeons. Metal-on-metal bearings have the benefit of decreased wear and large-diameter heads that provide added stability, yet complications related to metal hypersensitivity and wear have tempered enthusiasm for this bearing surface and have called into question whether the proposed benefits of this new technology will truly decrease complications and improve patient outcomes. We are fortunate to have all of these modern issues addressed critically by various articles in this symposium. I would like to personally thank all of the contributing authors for their excellent research presented in this symposium. The topics are timely and relevant and the quality of the work is exceptional. I would also like to thank the reviewers who contributed their time and expertise to critically review all the manuscripts and uphold strict scientific rigor. Finally, I would like to extend my sincere appreciation and personal gratitude to Paul Lotke and Dick Brand. Their tireless efforts and talents brought this symposium from concept to reality and it would not have been possible without them. I am hopeful the readership of CORR will enjoy and benefit from the outstanding works presented in this symposium and appreciate the critical scientific review involved. It is our goal that the information presented here allows the orthopaedic surgeon to make more informed and evidence-based decisions regarding the prevention and treatment of hip arthroplasty complications, improving safety and outcomes for patients. Fig. 1 R. Michael Meneghini, MD is shown.

Primary Hip Arthroplasty With 28-mm Metasul Articulation

This follow-up study reports on 69 patients at mean 13 years with total hip arthroplasty using 28-mm Metasul (Zimmer, Winterthur, Switzerland) metal-on-metal articulation. These results are not transferable to large–diameter head metal-on-metal articulations. Four new revisions, 3 for disassociation of the liner and 1 for mechanical loosening of the acetabulum, occurred since the previous report of mean 7.3 years. The prevalent cause of late revision is disassociation, which suggests a high frictional torque or impingement in these articulation surfaces. No revision was done for osteolysis. Overall, of the original 127 hips, 116 (91%) were known to have maintained their original components.

Metal Ion Release With Large-Diameter Metal-on-Metal Hip Arthroplasty

Preoperative and postoperative ion concentrations were measured in 29 metal-on-metal, large-diameter head total hip arthroplasty (LDH-THA) patients. Mean chromium, cobalt (Co), and titanium levels from LDH-THA were 1.3, 2.2, and 2.7 μg/L at 12 months. The open femoral head design showed significantly higher Co concentrations than the closed design (3.0 vs 1.8 μg/L, P = .037). Compared with previously published ion levels from a hip resurfacing system presenting the same bearing characteristics, Co levels were significantly higher in LDH-THA (2.2 vs 0.7 μg/L, P < .001). This study has demonstrated that the addition of a sleeve with modular junctions and an open femoral head design of LDH-THA causes more Co release than bearing surface wear (157% and 67%, respectively). Even if no pathologic metal ion threshold level has been determined, efforts should be made to minimize its release. We recommend modification or abandonment of the modular junction and femoral head open design for this specific LDH-THA system.

Metal-on-Metal Total Hip Arthroplasty Adverse Local Tissue Reaction

Metal-on-metal (MOM) bearings with large head diameter are commonly used for total hip arthroplasty (THA). They provide low wear and a reduced risk of dislocation. Since 2001, we have done 1327 primary THAs using this bearing surface. Using revision as an endpoint, survivorship is 94% at 8 years. Of the 17 revisions (1.3%), none have been for dislocation. Five patients (0.3%) have shown evidence of a local reaction to the MOM bearing which contributed to their failure and ultimate revision. All 5 presented with elevated inflammatory indexes and had a purulent-appearing joint effusion at revision. Two showed a necrotic periarticular tissue mass (pseudotumor). The presumed diagnosis of infection and the delay in diagnosis of reaction to the MOM with pathology complicated management.