Birmingham hip resurfacing: the prevalence of failure

Is there still an indication for the Birmingham Hip Resurfacing in femoral head osteonecrosis?

PURPOSE

Osteonecrosis of the femoral head (ONFH) is a progressive hip disease. Hip resurfacing arthroplasty (HRA) is a preferred surgical procedure among hip arthroplasty performed in young patients. The aim of this study is to show the long-term clinical and radiological results of HRA procedures performed for patients suffering from ONFH.

METHODS

Forty-five patients who underwent hip resurfacing with the diagnosis of femoral head osteonecrosis were included in the study. The Harris Hip Score (HHS) was used for clinical scoring of the patients. The blood chromium, cobalt, white blood cell (WBC) count, and CRP levels of patients were checked. Ultrasonography (USG) was performed for all patients at mid-term control checked for pseudo-tumours. For the radiological evaluation, acetabular inclination, stem shaft angle, prothesis-to-neck ratio, osteolysis zones, and heterotopic ossification were used.

RESULTS

The mean age of the patients was 46.6 ± 9.3 years, and the mean follow-up period was 11.83 ± 2.9 years. The mean HHS was 90.3 ± 12.8 for final follow-up. The mean WBC value was 8.2 109/L, mean CRP value was 6.3 mg/L, mean chromium value was 4.9 µg/L, and mean cobalt value was 1.8 µg/L. Inclination changing 0.2°(p = 0.788), stem shaft angle changing 0.7°(p = 0.424), and neck-to-prosthesis ratio changing 0.01°(p = 0.075). No pseudo-tumours were detected in any patients in USG examination.

CONCLUSION

HRA provides long-term implant survival and excellent clinical outcomes for end-stage ONFH patients with low complication rates.

Metallosis in Total Hip Arthroplasty

» Metallosis is a rare but significant complication that can occur after total hip arthroplasty (THA) for a variety of reasons but most commonly in patients with metal-on-metal implants.» It is characterized by the visible staining, necrosis, and fibrosis of the periprosthetic soft tissues, along with the variable presence of aseptic cysts and solid soft tissue masses called pseudotumors secondary to the corrosion and deposition of metal debris.» Metallosis can present with a spectrum of complications ranging from pain and inflammation to more severe symptoms such as osteolysis, soft tissue damage, and pseudotumor formation.» Workup of metallosis includes a clinical evaluation of the patient's symptoms, imaging studies, serum metal-ion levels, and intraoperative visualization of the staining of tissues. Inflammatory markers such as erythrocyte sedimentation rate and C-reactive protein along with intraoperative frozen slice analysis may be useful in certain cases to rule out concurrent periprosthetic joint infection.» Management depends on the severity and extent of the condition; however, revision THA is often required to prevent rapid progression of bone loss and tissue necrosis.

Strategies for fixation of periprosthetic fragility fractures of the neck of femur below a well-functioning hip resurfacing arthroplasty: A case-series

Introduction

Metal-on-metal Hip Resurfacing (HR) was performed in many young individuals as it conserved bone stock and had low wear rates, before it became less popular due to the detection of Adverse Reactions to Metal Debris. As such, many patients in the community have well-functioning HRs and as they age, the incidence of fragility fractures of the neck of femur around the existing implant is expected to increase. These fractures are amenable to surgical fixation as adequate bone stock remains in the head of the femur and the implants are well fixed.

Case-series

We present a series of six cases which were treated by fixation using locked plates (3), dynamic hip screws (2) and cephalo-medullary nail (1). Four cases achieved clinical and radiographic union with good function. One case had a delayed union, though union was finally achieved at 23 months. One case had an early failure necessitating revision to a Total Hip Replacement after 6 weeks.

Discussion

We highlight the geometrical principles of placing fixation devices under an HR femoral component. We have also conducted a literature search and present details of all case reports to date.

Conclusion

Fragility per-trochanteric fractures under a well-fixed HR with good baseline function are amenable to fixation using a variety of methods including large screw devices that are commonly used in this location. Locked plates including variable angle locking designs should be kept available if needed.

Dislocation of a McMinn-Like Prosthesis with Distinctive Metallosis and Fracture of the Os Ilium

Osteoarthritis of the hip joint (coxarthrosis) is the most common hip disease in adults. Since the 1960s, total hip arthroplasty (THA) has made great progress and is nowadays one of the most frequently used procedures in orthopedic surgery. Different bearing concepts exist in various implant designs. A metal-on-metal bearing can create metal debris and lead to metallosis. We present a unique case of a 78-year old woman, who received hip resurfacing with a McMinn-like prosthesis 15 years ago. Over the cause of time, metallosis developed and created a bone cyst in the Os ilium, and osteolysis led to a dislocation of the femoral implant. A minor stumble fall led to a fracture of the Os ilium. We present our treatment method with implantation of a cemented THA and refill of the bone cyst with bone from allogene femoral heads. The surgery led to a reconstruction of the physiological center of rotation in the hip. Consequently, to the inpatient stay, the patient took part in a follow-up treatment with intensive physiotherapy. Taken together, the results after total hip arthroplasty are more superior to other hip surface replacements in terms of longevity and patient satisfaction. Especially, metal-on-metal bearing couples carry a great risk of metallosis, which goes a long with pseudotumors, osteolysis, and the elevated metal ions in the blood. Since this case is unique in the literature, no guidelines are noted for surgical treatment. In our opinion, a periprosthetic fracture of this type should be performed in a hospital using extensive endoprosthetic expertise.

Evaluating Alternate Registration Planes for Imageless, Computer-Assisted Navigation During Total Hip Arthroplasty

BACKGROUND

Imageless computer navigation improves component placement accuracy in total hip arthroplasty (THA), but variations in the registration process are known to impact final accuracy measurements. We sought to evaluate the registration accuracy of an imageless navigation device during THA performed in the lateral decubitus position.

METHODS

A prospective, observational study of 94 patients undergoing a primary THA with imageless navigation assistance was conducted. Patient position was registered using 4 planes of reference: the patient's coronal plane (standard method), the long axis of the surgical table (longitudinal plane), the lumbosacral spine (lumbosacral plane), and the plane intersecting the greater trochanter and glenoid fossa (hip-shoulder plane). Navigation measurements of cup position for each plane were compared to measurements from postoperative radiographs.

RESULTS

Mean inclination from radiographs (41.5° ± 5.6°) did not differ significantly from inclination using the coronal plane (40.9° ± 3.9°, P = .39), the hip-shoulder plane (42.4° ± 4.7°, P = .26), or the longitudinal plane (41.2° ± 4.3°, P = .66). Inclination measured using the lumbosacral plane (45.8° ± 4.3°) differed significantly from radiographic measurements (P < .0001). Anteversion measured from radiographs (mean: 26.1° ± 5.4°) did not differ significantly from the hip-shoulder plane (26.6° ± 5.2°, P = .50). All other planes differed significantly from radiographs: coronal (22.6° ± 6.8°, P = .001), lumbosacral (32.5° ± 6.4°, P < .0001), and longitudinal (23.7° ± 5.2°, P < .0001).

CONCLUSION

Patient registration using any plane approximating the long axis of the body provided a frame of reference that accurately measured intraoperative cup position. Registration using a plane approximating the hip-shoulder axis, however, provided the most accurate and consistent measurement of acetabular component position.

Fixation and Implant Retention of Extracapsular Femoral Neck Periprosthetic Fractures Around Hip Resurfacing Arthroplasty - A Case Series

BACKGROUND

Extracapsular femoral neck fractures in the presence of a resurfacing hip arthroplasty (RHA) appear to be independent of suboptimal technique during the initial implantation of the RHA and present with a similar etiology as native hip fractures - that is, a fragility fracture related to pathological or age-related osteoporosis, as a consequence of trauma. In the presence of a well-fixed and previously well-functioning RHA, the options for management include revision arthroplasty or open reduction and internal fixation (ORIF). In the absence of loosening through mechanisms of wear, infection, metallosis, or suboptimal prosthesis positioning, many authors have advocated ORIF with implant retention. However, there is often debate regarding the use of total hip arthroplasty in these cases.

CASE SERIES

The authors conducted a thorough assessment of the literature followed by a retrospective review of outcomes for three patients treated by ORIF with implant retention for extracapsular femoral neck fractures around a RHA, using a standardized technique. All patients were independently mobile and active with well-fixed and well-functioning RHAs before the date of injury. All patients suffered low-energy trauma resulting in the fracture. There were no intraoperative or perioperative complications. All patients achieved full weight-bearing status and independent mobility. Two patients achieved radiographic union and returned to full range of movement and independent mobilization comparable to their preoperative state. One patient was lost to follow-up.

CONCLUSION

The authors believe that fixation of extracapsular proximal femoral fractures distal to a well-fixed, well-functioning RHA is a good management option in an independent and active patient. A higher level of evidence is needed to investigate the surgical management options of these injuries comparing osteosynthesis with revision arthroplasty.

Quadrilateral Surface Restoration by Medial Buttressing Before Revision in Periprosthetic Acetabular Fracture: A Case Report

CASE

We report a case of periprosthetic acetabular fracture with pelvic discontinuity (PAFPD) classified Paprosky IIIb around an infected hip resurfacing prosthesis. A 3-stage revision was performed with (1) implants removal and surgical debridement to treat the infection; (2) open reduction and internal fixation using a medial buttress plate to treat pelvic discontinuity; and (3) custom-made total hip replacement with acetabular-ring reinforcement. The patient recovered with excellent clinical and radiographic results at 4-year follow-up.

CONCLUSIONS

In complex cases of PAFPD, a collaboration between pelvic trauma surgeons and orthopaedic hip surgeons allows to provide stability for revision surgeries with good outcomes.

Routine Fracture Fixation for a Periprosthetic Hip Fracture Below Birmingham Hip Resurfacing: A Case Report

CASE

We present a case of a 56-year-old man who sustained a basal cervical periprosthetic fracture around a well-fixed metal-on-metal hip resurfacing arthroplasty (MoMHRA). Although several fixation methods have been described, there seems to be no consensus about the optimal fixation method for fractures around MoMHRAs. This fracture could be regarded as a Vancouver type-B1 or -C periprosthetic fracture, so we successfully treated our patient in a standard way with a dynamic hip screw (DHS) and one cannulated hip screw.

CONCLUSION

We describe DHS fixation as a successful treatment option for periprosthetic hip fractures around well-fixed MoMHRA.

Return to sports after hip resurfacing versus total hip arthroplasty: a mid-term case control study

BACKGROUND

Hip resurfacing (HR) is an alternative to conventional total hip arthroplasty (THA) for the treatment of osteoarthritis (OA) in very active, young male patients. However, there is no study in the literature that has proven its benefits for high-impact sport over standard primary THA. The aim of the current study was to investigate the return to sport and function level of male patients after THA vs. HR.

MATERIALS AND METHODS

This prospective study is based on a telephone questionnaire for general health and sports activities. 40 HRs were matched with 40 THAs based on preoperative University of California Arthroplasty Score (UCLA), BMI, age at time of surgery and age at follow-up. The mean follow-up period was 56 months (range 24-87 months).

RESULTS

HR patients showed a significantly higher High-activity arthroplasty score (HAAS) (14.9 vs. 12.9, p < 0.001) and Lower extremity activity scale (LEAS) (15.9 vs. 14.1, p < 0.001) and reached significantly higher values in the Hip cycle score (HCS) (44.7 vs. 35.7 p = 0.037) and Impact score (IS) (40.9 vs. 29.6, p < 0.002) than THA patients. No significant differences were found in the HOOS function section (91.4 vs. 90.3, p = 0.803) and the Pain numeric rating scale (NRS)-11 (0.6 vs. 0.9 p = 0.169). Patients with HR had a slightly higher Harris hip score (HHS) (97.8 vs. 95.6, p = 0.015) CONCLUSION: The current study suggests that young male patients are able to engage in higher activity levels after HR compared to standard THA.

Acetabular Fracture Around a Birmingham Hip Resurfacing Prosthesis: A Case Report

CASE

A traumatic displaced transverse periprosthetic acetabular fracture around a well-functioning Birmingham hip resurfacing prosthesis was treated with open reduction and internal fixation. The acetabular component was found to be well-fixed intraoperatively and did not require revision. The patient recovered with excellent clinical and radiographic results at the 1-year follow-up with a Harris Hip Score of 94.

CONCLUSIONS

Internal fixation, rather than revision arthroplasty, offers acceptable outcomes in patients with periprosthetic acetabular fractures about well-fixed hip resurfacing prostheses. Radiographic and intraoperative assessment of stability is critical in guiding treatment.

Femoral Fixation Methods in Hip Resurfacing Arthroplasty: An 11-Year Retrospective Comparison of 4013 Cases

BACKGROUND

The optimal femoral fixation method remains unclear. To evaluate the role of femoral fixation techniques in hip resurfacing, we present a comparison of 2 consecutive groups: group 1 (739 hips) with cemented femoral components; group 2 (3274 hips) with uncemented femoral components.

METHODS

We retrospectively analyzed our clinical database to compare failures, reoperations, complications, clinical results, and radiographic measurements. Groups were consecutive, so cemented cases had longer follow-up. However, all patients from both groups were at least 2 years out from surgery. Two-year clinical and radiographic data were compared. Longer-term comparison data as well as Kaplan-Meier implant survivorship curves specifically focusing on femoral failure modes were analyzed.

RESULTS

Kaplan-Meier 10-year implant survivorship using nontraumatic femoral failure as an end point was 98.9% for the cemented and 100% for the uncemented femoral component. The uncemented, group 2 cases showed a significantly lower raw failure rate (1.1% vs 4.6%), 2-year failure rate (0.8% vs 2.8%), 2-year femoral failure rate (0.4% vs 0.9%), and a lower combined rate of femoral complications and failures (0.6% vs 1.8%). In cases that did not fail, patient mean clinical scores, pain scores, and combined range of motion were all significantly better for group 2.

CONCLUSION

We have demonstrated that in the fully porous-coated ReCap device, uncemented femoral fixation is superior to cemented fixation at 11 years follow-up (0.0% vs 1.1% late femoral loosening) in this single-surgeon cohort. Early femoral fractures also reduced from 0.8% to 0.3%, but this may be partially or completely due to a new bone density management program. This study demonstrates better femoral implant survivorship for the uncemented device compared to the cemented femoral resurfacing component for this implant design.

Computer-assisted navigation in Birmingham hip resurfacing: A case report

Component malpositioning during Birmingham hip resurfacing increases the risk for component wear, metallosis, component loosening, and the likelihood of dislocation and revision surgery. Computer-assisted navigation can increase the accuracy to which components are placed, and the utilization of this technology in Birmingham hip resurfacing is increasing. The present report summarizes the accuracy of acetabular component positioning in a Birmingham hip resurfacing case utilizing navigation. Intraoperative C-arm fluoroscopy following the use of the navigation tool confirmed excellent seating, positioning, and stability of the acetabular component. In addition, post-operative antero-posterior radiographs confirmed device accuracy and revealed a stable joint with no evidence of acetabular loosening or femoral fracture. Computer-assisted navigation may therefore be an effective tool to improve the accuracy of component positioning during Birmingham hip resurfacing.

Mid- to long-term results of resurfacing hip arthroplasty in Japanese patients: a comparison of osteoarthritic vs non-osteoarthritic patients

Past reports showed good mid-term results of RHA for Japanese patients. However, few reports have compared the mid- to long-term results for RHA in Japanese patients with and without osteoarthritis. Therefore, this study investigated the mid- to long-term results of RHA in Japanese patients with osteoarthritis compared to those without. We conducted a retrospective review of a consecutive series of 92 hips in 80 patients (59 men and 21 women). The minimum follow-up period was 5 years. The JOA hip scoring system was used to clinically evaluate hip function. In the radiological assessment, stem-shaft angle, inclination of the acetabular component, postoperative complications, and adverse reactions around RHA were evaluated. The 10-year survival rate using the Kaplan-Meier method was investigated to compare patients with and without osteoarthritis. A significant difference was observed between the preoperative and postoperative JOA hip scores of either group. Also, the radiological assessment revealed no significant changes in either group. All three revision THAs were performed on patients in the only non-osteoarthritis group. In the osteoarthritis group, the 10-year survival rate was 94% (95% CI 81.8-100) in males and 100% (95% CI 100) for females; in the non-osteoarthritis group, the rate was 80% (95% CI 55.1-100) in males and 66.7% (95% CI 13.3-100) for females. In conclusion, this study showed good mid- to long-term clinical results for young Japanese osteoarthritis patients, with less satisfactory mid- to long-term results in patients without osteoarthritis.

Stress Fracture of Proximal Femur after Hip Resurfacing Treated with Cannulated Screw

Stress fractures of the proximal femur are described in athletes and military personnel. In most cases, they are not treated surgically, except when they are at the top of the femoral neck and with cortical involvement. The return to sports is not recommended in patients with hip replacement, especially for the high rate of revision of implants in the younger patients. One of the major complications of hip resurfacing (HR) is the medial fracture of the femoral neck, which usually occurs within 9 weeks after surgery. The causes have to be attributed to a malposition of the femoral component or to an insufficient bone density. The case reported herein is unique because it describes a stress fracture on patient operated with HR, treated with screw fixation. Two years after surgery, the patient returned to his normal life, practicing sports, without progression of varus angulation of the stem.

CoCrMo alloy vs. UHMWPE Particulate Implant Debris Induces Sex Dependent Aseptic Osteolysis Responses In Vivo using a Murine Model

Background:

The rate of revision for some designs of total hip replacements due to idiopathic aseptic loosening has been reported as higher for women. However, whether this is environmental or inherently sex-related is not clear.

Objective:

Can particle induced osteolysis be sex dependent? And if so, is this dependent on the type of implant debris (e.g. metal vs polymer)? The objective of this study was to test for material dependent inflammatory osteolysis that may be linked to sex using CoCrMo and implant grade conventional polyethylene (UHMWPE), using an in vivo murine calvaria model.

Methods:

Healthy 12 week old female and male C57BL/6J mice were treated with UHMWPE (1.0um ECD) or CoCrMo particles (0.9um ECD) or received sham surgery. Bone resorption was assessed by micro-computed tomography, histology and histomorphometry on day 12 post challenge.

Results:

Female mice that received CoCrMo particles showed significantly more inflammatory osteolysis and bone destruction compared to the females who received UHMWPE implant debris. Moreover, females challenged with CoCrMo particles exhibited 120% more inflammatory bone loss compared to males (p<0.01) challenged with CoCrMo implant debris (but this was not the case for UHMWPE particles).

Conclusion:

We demonstrated sex-specific differences in the amount of osteolysis resulting from CoCrMo particle challenge. This suggests osteo-immune responses to metal debris are preferentially higher in female compared to male mice, and supports the contention that there may be inherent sex related susceptibility to some types of implant debris.

Intraoperative Complications and Mid-Term Follow-Up of Large-Diameter Head Metal-on-Metal Total Hip Arthroplasty and Hip Resurfacing Arthroplasty

BACKGROUND AND AIMS

Large-diameter head total hip arthroplasty and hip resurfacing arthroplasty were popular in Finland from 2000 to 2012 for the treatment of hip osteoarthritis. The aim of this retrospective study was to investigate the mid-term survival of large-diameter head total hip arthroplasty patients operated on in three university hospitals and to compare these results to the survival of hip resurfacing arthroplasty patients.

MATERIAL AND METHODS

A total of 3860 hip arthroplasties (3029 large-diameter head total hip arthroplasties in 2734 patients and 831 hip resurfacing arthroplasties in 757 patients) were operated on between January 2004 and December 2009. The mean follow-up was 4.3 years (range: 0.3-8.0 years) in the total hip arthroplasty group and 5.1 years (range: 1.7-7.9 years) in the hip resurfacing arthroplasty group. Cox multiple regression model and Kaplan-Meier survival analysis were used to study the survival of the total hip arthroplasties and the hip resurfacing arthroplasties. Intraoperative complications and reasons for revisions were also evaluated.

RESULTS

In Cox regression analysis, the hazard ratio for revision of hip resurfacing arthroplasty was 1.5 compared with large-diameter head total hip arthroplasty (95% confidence interval: 1.0-2.2) ( p = 0.029). The cumulative Kaplan-Meier survival rate was 90.7% at 7.7 years for the large-diameter head total hip arthroplasty (95% confidence interval: 86.8-94.6) and 92.2% at 7.6 years for hip resurfacing arthroplasty (95% confidence interval: 89.9-94.6). There were a total of 166/3029 (5.5%) intraoperative complications in the large-diameter head total hip arthroplasty group and 20/831 (2.4%) in the hip resurfacing arthroplasty group ( p = 0.001). Revision for any reason was performed on 137/3029 (4.5%) of the arthroplasties in the large-diameter head total hip arthroplasty group and 52/831 (6.3%) in the hip resurfacing arthroplasty group ( p = 0.04).

CONCLUSION

The mid-term survival of both of these devices was poor, and revisions due to adverse reactions to metal debris will most likely rise at longer follow-up. There were more intraoperative complications in the large-diameter head total hip arthroplasty group than in the hip resurfacing arthroplasty group.

Improving registration accuracy during total hip arthroplasty: a cadaver study of a new, 3-D mini-optical navigation system

INTRODUCTION

Maintaining accuracy of component placement is an important step in ensuring the long-term stability of components during total hip arthroplasty (THA). Computer-assisted navigation has improved accuracy but errors associated with the registration process are known to impact the accuracy of final measurements. The purpose of this cadaver study was to determine the registration error associated with a novel mini-navigation system.

METHODS

3 board-certified orthopaedic surgeons performed 4 THA procedures each via the posterolateral approach on 6 cadavers (12 hips) using the mini-navigation tool. Pre- and post-operative radiographs and post-operative computed tomography (CT) images were obtained. Image analysis was performed by 2 radiologists not involved in the surgical procedures. During registration, surgeons aligned the alignment rod with the anterior pelvic plane (APP) to provide a reference plane for comparison with traditional navigation. Cup position from the device was compared with measurements gathered from post-op imaging.

RESULTS

The mean difference between CT and device measurements for inclination was -1.7° (standard deviation [SD] 4.9°), while the mean absolute difference was 4.2° (SD 3.2°). The mean difference between anteversion angles calculated from CT scans and from the device was -3.5° (SD 4.5°), with an absolute difference of 4.0° (SD 4.0°). 100% (12/12) of inclination measurements and 92% (11/12) of anteversion measurements fell within both the clinical and statistical limits of agreement when analyzed via the Bland-Altman technique.

CONCLUSIONS

This study demonstrates that the registration error associated with this new mini-navigation system compares favourably with the known registration error associated with traditional navigation systems.

Interventions for Improving Hip Resurfacing Outcomes in Women: A High-Volume, Retrospective Study

BACKGROUND

Women seeking surgical intervention for their hip disorders will often find total hip arthroplasty (THA) presented as their only option. THA, when compared with hip resurfacing arthroplasty, removes substantially more bone-stock, limits range-of-motion, exhibits increased dislocation risk, and presents greater overall 10-year mortality rate. Despite these risks, most surgeons continue to select against women for hip resurfacing because registries notoriously report inferior survivorship when compared with men and THA.

METHODS

We investigated the reasons for why resurfacing arthroplasty devices survive poorly in women to develop interventions which might improve hip resurfacing outcomes in women. Using these findings, we developed a series of surgical interventions to treat the underlying issues. Herein, we compare 2 study groups: women who received hip resurfacings before (group 1) and after (group 2) these interventions.

RESULTS

Eight-year implant survivorship substantially improved from 89.6% for group 1 to 97.7% for group 2. Adverse wear-related failure, femoral component loosening, and acetabular component loosening were all significantly reduced in group 2, which we attribute to the implementation of our relative acetabular inclination limit guidelines, use of uncemented femoral fixation, and selection of the Tri-Spike acetabular component for supplemental fixation, respectively. Kaplan-Meier implant survivorship curves, grouped into 2-year time intervals, show that the disparity in failure rates between men and women is diminishing.

CONCLUSION

When experienced surgeons use refined and proper surgical technique, women show promise as excellent candidates for hip resurfacing as an alternative treatment for their debilitating hip conditions.

Bone preserving level of osteotomy in short-stem total hip arthroplasty does not influence stress shielding dimensions - a comparing finite elements analysis

Background

The main objective of every new development in total hip arthroplasty (THA) is the longest possible survival of the implant. Periprosthetic stress shielding is a scientifically proven phenomenon which leads to inadvertent bone loss. So far, many studies have analysed whether implanting different hip stem prostheses result in significant preservation of bone stock. The aim of this preclinical study was to investigate design-depended differences of the stress shielding effect after implantation of a selection of short-stem THA-prostheses that are currently available.

Methods

Based on computerised tomography (CT), a finite elements (FE) model was generated and a virtual THA was performed with different stem designs of the implant. Stems were chosen by osteotomy level at the femoral neck (collum, partial collum, trochanter sparing, trochanter harming). Analyses were performed with previously validated FE models to identify changes in the strain energy density (SED).

Results

In the trochanteric region, only the collum-type stem demonstrated a biomechanical behaviour similar to the native femur. In contrast, no difference in biomechanical behaviour was found between partial collum, trochanter harming and trochanter sparing models. All of the short stem-prostheses showed lower stress-shielding than a standard stem.

Conclusion

Based on the results of this study, we cannot confirm that the design of current short stem THA-implants leads to a different stress shielding effect with regard to the level of osteotomy. Somehow unexpected, we found a bone stock protection in metadiaphyseal bone by simulating a more distal approach for osteotomy. Further clinical and biomechanical research including long-term results is needed to understand the influence of short-stem THA on bone remodelling and to find the optimal stem-design for a reduction of the stress shielding effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1702-2) contains supplementary material, which is available to authorized users.

Adverse reaction to metal debris in a consecutive series of DUROM™ hip resurfacing: pseudotumour incidence and metal ion concentration

INTRODUCTION

The aim of this study was to evaluate the incidence of adverse reactions to metal debris (ARMD) in a consecutive series of DUROM™ Hip Resurfacing Arthroplasty (HRA) at mid-term follow-up.

METHODS

Between October 2003 and March 2007 a total of 134 consecutive DUROM™ HRA in 121 patients were performed at our institution. Follow-up could be obtained in 101 unrevised patients (83%) at a mean time of 8.51 ± 0.97 years postoperatively and included patient-related outcome measurement, plain radiographs, MARS-MRI as well as whole blood metal ion assessment.

RESULTS

17 (16.5%) out of 103 hips revealed pseudotumour occurrence in MRI investigation, 1 (10.6%) with a diameter of ≥2 cm. Higher incidence of pseudotumours was found patients with femoral component size <50 mm. 38 patients had elevated cobalt levels, 36 of them (35%) in the range of 2-7 μg/l and 2 patients (1.9%) at a rate of >7 μg/l. In contrast to cobalt determination, only elevated chromium values showed a positive association with pseudotumour occurrence and size.

DISCUSSION

A significant proportion of patients developed pseudotumours and metal ion elevation in a consecutive cohort of DUROM™ HRA after mid-term follow-up. The incidence, however, seems not to differ from results of other well performing resurfacing brands; clinical relevance of our findings is unclear. Regarding potential local as well as systemic effects of metal particle release, close follow-up of patients is essential, even with clinically well-performing implants.

Metal-on-metal hip resurfacing in patients younger than 50 years: a retrospective analysis : 1285 cases, 12-year survivorship

BACKGROUND

The Nordic registry reports patients under 50 years old with total hip replacements realize only 83% 10-year implant survivorship. These results do not meet the 95% 10-year survivorship guideline posed by the UK's National Institute for Health and Care Excellence (NICE) in 2014.

METHODS

The purpose of this study is threefold: First, we evaluate if metal-on-metal hip resurfacing arthroplasty meets these high standards in younger patients. Next, we compare outcomes between age groups to determine if younger patients are at higher risk for revision or complication. Lastly, we assess how outcomes between sexes changed over time. From January 2001 to August 2013, a single surgeon performed 1285 metal-on-metal hip resurfacings in patients younger than 50 years old. We compared these to an older cohort matched by sex and BMI.

RESULTS

Kaplan-Meier implant survivorship was 96.5% at 10 years and 96.3% at 12 years; this did not differ from implant survivorship for older patients. Implant survivorship at 12 years was 98 and 93% for younger men and women, respectively; survivorship for women improved from 93 to 97% by using exclusively Biomet implants. There were four (0.3%) adverse wear-related failures, with no instances of wear or problematic ion levels since 2009. Activity scores improved from 5.4 ± 2.3 preoperatively to 7.6 ± 1.9 postoperatively (p < 0.0001), with 43% of patients reporting a UCLA activity score of 9 or 10.

CONCLUSIONS

Hip resurfacing exceeds the stricter 2014 NICE survivorship criteria independently in men and women even when performed on patients under 50 years old.

Birmingham Hip Resurfacing in Patients 55 Years or Younger: Risk Factors for Poor Midterm Outcomes

BACKGROUND

Birmingham hip resurfacing (BHR) is the only Food and Drug Administration-approved hip resurfacing system available in the United States and is used as an alternative to conventional total hip arthroplasty in younger patients. The purpose of this study is to report on the midterm outcomes of BHR in patients 55 years and younger, and specifically to examine the risk factors for aseptic failure, all-cause revision, and complications in this patient population.

METHODS

Four hundred forty-two consecutive patients with 5-year follow-up were retrospectively reviewed. Multivariate analyses were conducted to control for potential confounding factors identified by univariate analyses.

RESULTS

Mean follow-up was 71.68 ± 10.24 months. Among the potential risk factors, only female gender and smaller head sizes had a significant univariate relationship with aseptic revision, all-cause revision, and all-cause complications. When both risk factors were included in a multivariable logistic regression model, analyses showed both variables were closely related, with female gender a better predictor of adverse outcomes than head size (ie, small head size can be thought of as a proxy for female gender). The 5-year implant survival is 95.1% females compared to 99.0% in males.

CONCLUSION

Hip resurfacing with BHR has excellent survival rates in young patients with degenerative hip disease. Although this study suggests that females with small templated head sizes may not be suitable candidates for BHR, further studies are needed to better understand the underlying differences in gender.

Females with Unexplained Joint Pain Following Total Joint Arthroplasty Exhibit a Higher Rate and Severity of Hypersensitivity to Implant Metals Compared with Males: Implications of Sex-Based Bioreactivity Differences

BACKGROUND

Recent studies indicate that females demonstrate an increased risk of experiencing adverse local tissue reactions, aseptic loosening, and revision after primary metal-on-metal hip resurfacing arthroplasty compared with males; the underlying biological mechanisms responsible for sex discrepancies in implant failure remain unclear. In addition to anatomical and biomechanical sex differences, there may be inherent immunological disparities that predispose females to more aggressive adaptive immune reactivity to implant debris, i.e., metal sensitivity.

METHODS

In this retrospective study, we analyzed sex-associated rates and levels of metal sensitization in 1,038 male and 1,575 female subjects with idiopathic joint pain following total joint arthroplasty (TJA) who were referred for in vitro metal-sensitivity testing.

RESULTS

Females demonstrated a significantly higher rate and severity of metal sensitization compared with males. The median lymphocyte stimulation index (SI) among males was 2.8 (mean, 5.4; 95% confidence interval [CI], 4.9 to 6.0) compared with 3.5 (mean, 8.2; 95% CI, 7.4 to 9.0) among females (p < 0.05). Forty-nine percent of females had an SI of ≥4 (reactive) compared with 38% of males, and the implant-related level of pain was also significantly (p < 0.0001) higher among females (mean, 6.8; 95% CI, 6.6 to 6.9) compared with males (mean, 6.1; 95% CI, 6.0 to 6.3).

CONCLUSIONS

In a select group of patients who had joint pain following TJA and no evidence of infection and who were referred for metal-sensitivity testing, females exhibited a higher level of pain and demonstrated a higher rate and severity (as measured by lymphocyte SI) of metal sensitization compared with males.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Bilateral fixation of a periprosthetic intertrochanteric hip fracture below Birmingham hip resurfacing

This case report involves a 59-year-old woman with a traumatic right intertrochanteric hip fracture below a previous Birmingham hip resurfacing (BHR). This woman had almost an identical fracture on the left hip 3 years before which was treated with a proximal femoral locking compression plate. Of note periprosthetic fractures following hip resurfacing are usually subcapital and treated with a revision or conservative management. We present an unusual surgical problem that has occurred twice in the same patient and has been treated effectively on both occasions using proximal femoral plating. To the best of our knowledge, there have been no other reports of bilateral periprosthetic fractures being treated in this way.

Mid-Term Results and Predictors of Patient-Reported Outcomes of Birmingham Hip Resurfacing

BACKGROUND

Birmingham hip resurfacing (BHR) is the only Food and Drug Administration approved resurfacing option currently available in the United States. While adequate BHR outcomes are established, there is a paucity of US-based literature demonstrating factors critical to improve patient reported outcomes (PROs). This study answers: (1) What is the implant survivorship in a large US cohort? (2) Which preoperative factors result in higher PRO scores over 5 years postoperatively?

METHODS

A retrospective 541 hip single-surgeon cohort with mean of 6.2 years follow-up (range 5-8.1) was collected. Preoperative patient/implant variables, including postoperative radiographic acetabular inclination and femoral component position, clinical outcomes, and follow-up PRO questionnaire information were collected. Validated PROs included the Hip Disability and Osteoarthritis Outcome Score (HOOS), Veterans Rand-12, and University of California Los Angeles (UCLA) activity. PROs were modeled with ordinary least squares then used to create nomograms.

RESULTS

Average patient age was 53 years with 391 (72%) males. Seven hips were revised, resulting in an overall survival of 98.8% at 5 years. Predictive modeling identified preoperative variables (sex, body mass index, smoking, and comorbidity) that had statistically significant associations with HOOS pain (P = .049), HOOS activities of daily living (P = .017), UCLA activity (P < .001), and Veterans Rand-12 physical (P < .001) PROs at latest follow-up. Nomograms predicted follow-up PROs using preoperative patient-specific variables.

CONCLUSION

This study documents excellent survival of the largest reported single-center cohort of BHRs in the United States with a mean 6.2 years follow-up. Multivariate modeling shows male nonsmokers with low body mass index, and no comorbidities will have less hip pain, better function in daily life, higher activity, and better general physical health after BHR arthroplasty.

The Diagnosis of Infection in Metal-on-Metal Hip Arthroplasties

BACKGROUND

Distinction of aseptic from septic hip arthroplasty failure can be challenging. Some studies report an increased incidence of septic failure with metal-on-metal (MoM) hip arthroplasties. The Musculoskeletal Infection Society (MSIS) have formulated criteria to facilitate the diagnosis of periprosthetic joint infection (PJI). In this study, we determined the prevalence and histologic features of septic MoM hip failure.

METHODS

Overall, 104 cases of failed MoM hip arthroplasty, classified as septic or aseptic by MSIS microbiological criteria, were analyzed. The overall prevalence of septic failure was determined and the nature of the causative organisms noted. The extent of the neutrophil polymorph (NP) infiltrate in periprosthetic tissue in all cases was analyzed by hematoxylin-eosin and chloroacetate esterase staining.

RESULTS

The prevalence of septic MoM hip arthroplasty failure was 6.7%. Infective organisms were coagulase-negative Staphylococcus in 4 cases; Staphylococcus aureus, Streptococcus, and Propionibacterium species were isolated in the remaining cases. Chloroacetate esterase staining facilitated identification of NPs. All cases of PJI contained more than 5 NPs per high-power field (HPF) on average. Four cases of aseptic MoM implant failure contained scanty or scattered NPs (less than 5 per HPF on average).

CONCLUSION

The prevalence of PJI as a cause of MoM hip arthroplasty failure was relatively high compared to other hip bearing combinations; however, the organisms responsible were similar. Histologically, a minority of aseptic MoM implant failures contained some NPs, but the MSIS criteria for the histologic diagnosis of PJI (>5 NPs/HPF) correctly identified all microbiologically confirmed cases of septic failure.

Predicting high blood metal ion concentrations following hip resurfacing

PURPOSE

To determine whether gender, femoral head size, acetabular inclination, and time since surgery predicted high blood metal ion concentrations following Birmingham Hip Resurfacing (BHR).

METHODS

BHR patients with unilateral bearings at one specialist centre with blood cobalt and chromium concentrations measured up to May 2013 were included. This comprised a mixed (at-risk) group including symptomatic patients and asymptomatic individuals with specific clinical and/or radiological findings. Blood sampling was at a mean of 7.5 years (range 1-15.4 years) postoperatively.

RESULTS

Of 319 patients (mean age 49.3 years; 53% male), blood metal ions greater than 7 µg/l were observed in 9% (n = 28). Blood metal ions were significantly higher in females (p&lt;0.001), femoral head sizes ≤48 mm (p&lt;0.01), and cup inclinations &gt;55° (p&lt;0.001). Linear regression demonstrated femoral head size was responsible for the highest proportion of variance in blood metal ions (cobalt p&lt;0.001, R2 = 8%; chromium p&lt;0.001, R2 = 11%). Analysis of femoral head size and inclination together demonstrated 36% of BHRs with head sizes of 38-44 mm and inclination &gt;55° had blood metal ions &gt;7 µg/l. BHR 10-year survival for this at-risk group was 91% (95% confidence intervals 86.0%-95.0%) with 30 hips revised.

CONCLUSIONS

If blood metal ions are used to screen hip resurfacing patients for adverse reactions to metal debris it is recommended those with small femoral head sizes (38-44 mm) and high acetabular inclinations (&gt;55°) are targeted. These findings require validation in other cohorts as they may not be applicable to all hip resurfacing devices given the differences in radial clearance, coverage arc, and metallurgy.

Sequelae of large-head metal-on-metal hip arthroplasties: Current status and future prospects

Large-head metal-on-metal (MoM) bearings were re-popularised in the late 1990s with the introduction of modern hip resurfacing (HR), followed closely by large metal head total hip arthroplasty (THA). A worldwide increase in the use of MoM hip arthroplasty subsequently saw a sharp decline, due to serious complications.MoM was rapidly adopted in the early 2000s until medical device alerts were issued by government regulatory agencies and national and international organisations, leading to post-marketing surveillance and discontinuation of these implants.Guidelines for MoM hip implant follow-up differ considerably between regulatory authorities worldwide; this can in part be attributed to missing or conflicting evidence.The authors consider that the use of large-head MoM THA should be discontinued. MoM HR should be approached with caution and, when considered, should be used only in patients who meet all of the recommended selection criteria, which limits its indications considerably.The phased introduction of new prostheses should be mandatory in future. Close monitoring of outcomes and long-term follow-up is also necessary for the introduction of new prostheses. Cite this article: van Lingen CP, Zagra LM, Ettema HB, Verheyen CC. Sequelae of large-head metal-on-metal hip arthroplasties: current status and future prospects. EFORT Open Rev 2016;1:345-353. DOI: 10.1302/2058-5241.1.160014.

Prevalence of and Risk Factors for Hip Resurfacing Revision: A Cohort Study Into the Second Decade After the Operation

BACKGROUND

Most metal-on-metal hip resurfacing (MoMHR) designs have experienced high short-term failure rates because of pseudotumors. The impact of this complication into the second decade after the procedure is unknown. We investigated (1) the prevalence of, and risk factors for, all-cause and pseudotumor-related revision at up to 15 years following MoMHR and (2) whether risk factors were sex-specific.

METHODS

This single-center prospective cohort study included 1,429 MoMHRs (1216 patients; 40% female) implanted between 1999 and 2009. Patients were contacted in 2010 and 2012 as per national recommendations. Patients with symptoms related to the hip and/or suboptimal Oxford Hip Scores (≤41 of 48 points) underwent cross-sectional imaging and blood metal-ion sampling. Revision diagnoses were established using operative and histopathological findings. Multivariate Cox proportional hazard models were used to assess the association of predictor variables with the time to all-cause and pseudotumor-related revisions.

RESULTS

One hundred and eighty MoMHRs (12.6%) were revised for all causes, and 111 (7.8% of the series and 61.7 % of all revisions) were revised because of pseudotumor. Survival analysis showed the 15-year cumulative revision rate for all causes to be 19.5% (95% confidence interval [CI] = 16.2% to 23.2%) and the 15-year rate of revision due to pseudotumor to be 14.0% (95% CI = 11.0% to 17.7%). Small femoral head size (hazard ratio [HR] per 2 mm = 0.92, 95% CI = 0.88 to 0.97; p = 0.003) and certain implant designs (HR = 1.55 to 3.01; p ≤ 0.029) significantly increased the all-cause revision risk. Female sex (HR = 2.03, 95% CI = 1.19 to 3.44; p = 0.009) and young age (HR per year = 0.98, 95% CI = 0.96 to 1.00; p = 0.020) significantly increased the pseudotumor-related revision risk but not the all-cause revision risk. Risk factors for all-cause and pseudotumor-related revision were sex-specific. In females, small femoral head size (p = 0.014) increased the all-cause revision risk, and young age was the only predictor of pseudotumor-related revision (p = 0.019). In males, implant design was the only predictor of all-cause revision (p ≤ 0.015) and pseudotumor-related revision (p = 0.001).

CONCLUSIONS

The prevalence and rates of revision for all causes and pseudotumor were high at up to 15 years following MoMHR. Predictors of revision differed between all-cause and pseudotumor-related revisions and were sex-specific. These factors must be appropriately weighted when risk-stratifying patients with MoMHRs for surveillance.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Identifying the procedural gap and improved methods for maintaining accuracy during total hip arthroplasty

Osteoarthritis is a ubiquitous condition, affecting 26 million Americans each year, with up to 17% of adults over age 75 suffering from one variation of arthritis. The hip is one of the most commonly affected joints and while there are conservative options for treatment, as symptoms progress, many patients eventually turn to surgery to manage their pain and dysfunction. Early surgical options such as osteotomy or arthroscopy are reserved for younger, more active patients with less severe disease and symptoms. Total hip arthroplasty offers a viable solution for patients with severe degenerative changes; however, post-surgical discrepancies in leg length, offset and component malposition are common and cause significant complications. Such discrepancies are associated with consequences such as low back pain, neurological deficits, instability and overall patient dissatisfaction. Current methods for managing leg length and offset during hip arthroplasty are either inaccurate and susceptible to error or are cumbersome, expensive and lengthen surgical time. There is currently no viable option that provides accurate, real-time data to surgeons regarding leg length, offset and cup position in a cost-effective manner. As such, we hypothesize that a procedural gap exists in hip arthroplasty, a gap into which fall a large majority of arthroplasty patients who are at increased risk of complications following surgery. These complications and associated treatments place significant stress on the healthcare system. The costs associated with addressing leg length and offset discrepancies can be minor, requiring only heel lifts and short-term rehabilitation, but can also be substantial, with revision hip arthroplasty costs of up to $54,000 per procedure. The need for a cost-effective, simple to use and unobtrusive technology to address this procedural gap in hip arthroplasty and improve patient outcomes is of increasing importance. Given the aging of the population, the projected increases in the volume of procedures over the coming decades and the economic pressures associated with downward pricing pressure and bundled payments, the need to address this gap is underscored.

Medium-term results following large diameter metal-on-metal total hip arthroplasty: increasing failure after 6 years

PURPOSE

The main aim of our study is to report the medium-term survivorship of Birmingham Hip Resurfacing (BHR) cup and a large modular metal head (MMT) on an uncemented Freeman femoral stem. No results have been reported till date with these implants combinations.

METHODS

A total of 205 metal-on-metal total hip replacements (MoM THRs) were performed on 190 patients from October 2002 to November 2004. Prior to the Medicines and Healthcare Products Regulatory Agency (MHRA) guidelines, the patients were followed up at 3, 6 and 12 months postoperatively and annually thereafter. Following the MHRA alert in 2010, the patients were followed-up as per the MHRA guidelines.All statistical analyses were conducted using Stata 13.

RESULTS

At a mean follow-up of 10.5 years, a total of 42 out of 205 hips were revised for reasons related to ALTR. The failure rates increased significantly over time (7% at 6 years and 29% at 10-year follow-up). The analysis showed no statistically significant association to age, gender, side, BMI or component size or position (p&lt;0.05). Blood metal ions showed a poor discriminant ability to separate failed from well-functioning MoM hip replacements.

CONCLUSIONS

Large head MoM BHR on an uncemented stem has extremely high failure rate. The authors do not recommend the use of large head MoM articulation in total hip arthroplasty in the wake of this report and similar findings across the world. Continued surveillance of these implants is required as the failure rates increase with time.

Birmingham hip resurfacing in patients who are seventy years of age or older

There is no published literature to support mid to long term results of hip resurfacing (HR) arthroplasty in patients over the age of 70 years. The purpose of our study was to evaluate the function HR in this age group (70 or older at the time of surgery) at medium to long term follow-up. Between July 1997 and November 2002, the Oswestry Outcome Centre independently and prospectively collected data on 5000 Birmingham Hip Resurfacings (BHRs). 106 had been implanted in elderly patients who were 70 years of age or older. The post-operative Harris and Merle D'Aubigné and Postel (MDP) hip scores and causes for revision were used to ascertain function and implant survival. Hip scores for the older BHR patients were compared with those from younger patients. The average age at surgery of the elderly BHR cohort was 73.2 years (range, 70.0 to 87.9 years) with a mean follow-up of 7.1 years (range, 0.5 to 10.9 years). Four patients had a femoral neck fracture and required conversion to a conventional total hip replacement. There were no patients lost to follow-up and no dislocations in this series. The median Harris hip score (HHS) was significantly better in the younger BHR group compared with the elderly BHR group, (96 vs. 94 p=0.008). There was no significant difference in recovery rates after surgery. There was a significantly higher rate of revision in women than men among the elderly patients (male= 1 of 65 (1.5%); women = 3 of 19 (15.8%), p=0.03). At latest follow-up the elderly patients continued to function well when compared with the younger BHR patients. There was a high mid to long term success rate after HR in patients who were 70 years of age or older, without the failure burden possibly anticipated. Elderly patients had a poorer functional outcome, but a difference in HHS of two points may be of only minor clinical significance.

Conversion of a failed hip resurfacing arthroplasty to total hip arthroplasty: pearls and pitfalls

Surface replacement arthroplasty (SRA) remains a viable alternative to total hip arthroplasty (THA) in appropriately selected, active adults with degenerative hip disease. However, orthopedic surgeons are facing a number of scenarios where revision of one or both components of an SRA is indicated. Indications for revision vary and impact the potential outcomes of conversion of a SRA to THA. While clinical outcomes are generally favorable, a growing body of data illustrates patients who undergo conversion of a SRA to THA to be at increased risk of requiring a repeat revision surgery and experiencing functional outcomes inferior to that of a primary THA. The results of patients undergoing conversion of a SRA to THA highlight the need for careful patient selection, thorough preoperative counseling, and technical precision when performing a SRA. Furthermore, a systematic approach to the failed SRA is necessary to ensure optimal clinical results.

Combined Vascular and Orthopaedic Approach for a Pseudotumor Causing Deep Vein Thrombosis after Metal-on-Metal Hip Resurfacing Arthroplasty

Introduction. Metal-on-metal (MoM) hip resurfacings have been associated with a variety of complications resulting from adverse reaction to metal debris. Pseudotumors have rarely been reported to cause deep venous thrombosis (DVT). Study Design. A case report and a review of the literature. Case Presentation. A 75-year-old female who had left metal-on-metal hip resurfacing 6 years ago presented with left groin pain associated with unilateral lower limb edema and swelling. By duplex and MRI studies, our patient had an extensive soft tissue necrosis associated with a large pelvic mass causing extensive DVT of the lower limb secondary to mechanical compression of the left iliac vein. Results. Our case was initially treated for DVT followed by dual surgical approach. The pseudotumor was excised through a separate iliofemoral approach and revision of the hip implant was undertaken through a posterior approach in the same setting. An inferior vena cava (IVC) filter was inserted to minimise the perioperative risks of handling the iliac veins. Conclusion. A combined approach with vascular surgeons is required. Combined resection of the pseudotumor and revision of the metal bearing surfaces is essential, in order to achieve a good surgical outcome in this rare complication.

Are There Long-term Benefits to Cementing the Metaphyseal Stem in Hip Resurfacing?

BACKGROUND

Cementing the metaphyseal stem during hip resurfacing surgery improves the initial fixation of the femoral component. However, there may be long-term detrimental effects such as stress shielding or an increased risk of thermal necrosis associated with this technique.

QUESTIONS/PURPOSES

We compared (1) long-term survivorship free from radiographic femoral failure, (2) validated pain scores, and (3) radiographic evidence of component fixation between hips resurfaced with a cemented metaphyseal stem and hips resurfaced with the metaphyseal stem left uncemented.

METHODS

We retrospectively selected all the patients who had undergone bilateral hip resurfacing with an uncemented metaphyseal stem on one side, a cemented metaphyseal stem on the other side, and had both surgeries performed between July 1998 and February 2005. Forty-three patients matched these inclusion criteria. During that period, the indications for cementing the stem evolved in the practice of the senior author (HCA), passing through four phases; initially, only hips with large femoral defects had a cemented stem, then all stems were cemented, then all stems were left uncemented. Finally, stems were cemented for patients receiving small femoral components (< 48 mm) or having large femoral defects (or both). Of the 43 cemented stems, two, 13, 0, and 28 came from each of those four periods. All 43 patients had complete followup at a minimum of 9 years (mean, 143 ± 21 months for the uncemented stems; and 135 ± 22 months for the cemented stems; p = 0.088). Survivorship analyses were performed with Kaplan-Meier and Cox proportional hazards ratios using radiographic failure of the femoral component as the endpoint. Pain was assessed with University of California Los Angeles (UCLA) pain scores, and radiographic femoral failure was defined as complete radiolucency around the metaphyseal stem or gross migration of the femoral component.

RESULTS

There were four failures of the femoral component in the press-fit stem group while the cemented stem group had no femoral failures (p = 0.0471). With the numbers available, we found no differences between the two groups regarding pain relief or radiographic appearance other than in patients whose components developed loosening.

CONCLUSIONS

Cementing the metaphyseal stem improves long-term implant survival and does not alter long-term pain relief or the radiographic appearance of the proximal femur as had been a concern based on the results of finite element studies. We believe that patients with small component sizes and large femoral head defects have more to gain from the use of this technique which adds surface area for fixation, and there is no clinical downside to cementing the stem in patients with large component sizes.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Hip Resurfacing Implants

EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Describe the advantages of hip resurfacing. 2. Describe the disadvantages of hip resurfacing. 3. Identify the population in which hip resurfacing is most often indicated. 4. Demonstrate how to properly postoperatively manage patients with metal-on-metal prostheses. Hip resurfacing offers a suitable solution for young patients affected by hip disease who have high function demands and good bone quality. Bone stock preservation, restoration of the normal proximal femur anatomy, the lack of stress shielding, and the possibility of resuming sporting activity are proven advantages of hip resurfacing. However, there are some disadvantages, such as fracture of the femoral neck, onset of neck narrowing, and possible complications due to the metal-on-metal bearings, including pseudotumors, peri-implant osteolysis, and chronic elevation of metal ions in serum levels. Recent data suggest that the ideal candidate for hip resurfacing is an active male, younger than 65 years, with primary or posttraumatic osteoarthritis, and with a femoral head diameter larger than 50 to 54 mm. Based on these selection criteria, the literature reports implant survival to be similar to that of total hip arthroplasty. The current authors' experience confirms a low failure rate and excellent functional outcomes, with metal ion serum levels becoming stable over time in well-functioning implants. Proper surgical technique, correct patient selection, and the right choice of a well-established prosthetic model are essential elements for the long-term success of these implants.

Do Complication Rates Differ by Gender After Metal-on-metal Hip Resurfacing Arthroplasty? A Systematic Review

BACKGROUND

Although metal-on-metal (MoM) bearing surfaces provide low rates of volumetric wear and increased stability, evidence suggests that certain MoM hip arthroplasties have high rates of complication and failure. Some evidence indicates that women have higher rates of failure compared with men; however, the orthopaedic literature as a whole has poorly reported such complications stratified by gender.

QUESTIONS/PURPOSES

This systematic review aimed to: (1) compare the rate of adverse local tissue reaction (ALTR); (2) dislocation; (3) aseptic loosening; and (4) revision between men and women undergoing primary MoM hip resurfacing arthroplasty (HRA).

METHODS

Systematic MEDLINE and EMBASE searches identified all level I to III articles published in peer-reviewed journals, reporting on the outcomes of interest, for MoM HRA. Articles were limited to those with 2-year followup that reported outcomes by gender. Ten articles met inclusion criteria. Study quality was evaluated using the Modified Coleman Methodology Score; the overall quality was poor. Heterogeneity and bias were analyzed using a Mantel-Haenszel statistical method.

RESULTS

Women demonstrated an increased odds of developing ALTR (odds ratio [OR], 5.70 [2.71-11.98]; p<0.001), dislocation (OR, 3.04 [1.2-7.5], p=0.02), aseptic loosening (OR, 3.18 [2.21-4.58], p<0.001), and revision (OR, 2.50 [2.25-2.78], p<0.001) after primary MoM HRA.

CONCLUSIONS

A systematic review of the currently available literature reveals a higher rate of complications (ALTR, dislocation, aseptic loosening, and revision) after MoM HRA in women compared with men. Although femoral head size has been frequently implicated as a prime factor in the higher rate of complication in women, further research is necessary to specifically probe this relationship. Retrospective studies of data available (eg, registry data) should be undertaken, and moving forward studies should report outcomes by gender (particularly complications).

LEVEL OF EVIDENCE

Level III, therapeutic study.

Short-term Results of Birmingham Hip Resurfacing in the United States

Previous data on the survivorship of the Birmingham Hip Resurfacing (BHR) implant have come from design surgeons and large national databases outside of the United States, and there is a lack of reported outcomes of surface replacement arthroplasty from US centers. A retrospective study was undertaken of 1271 hips treated with a BHR system (Smith & Nephew, Memphis, Tennessee) between June 2006 and September 2008 at 6 high-volume total joint centers in the United States. Demographic features, Harris Hip Score (HHS), and radiographic findings were recorded. Patients who did not have a 2-year follow-up visit were contacted by telephone. All patients were asked about complications, reoperations, or failure of the implants. Of the treated hips, 1144 (90%) had a minimum of 2 years of clinical follow-up (mean, 2.9 years; range, 1.8-4.2 years). Mean age was 52.3 years, and 75% of patients were men. Mean HHS improved from 55.8 preoperatively to 97.4 at the most recent follow-up (P<.001). There were 16 (1.4%) revisions to total hip arthroplasty (THA) for fracture (7), early dislocation (3), acetabular component malpositioning with pain (3; 1 with metallosis), infection (1), femoral loosening (1), and pseudotumor (1). There were 9 additional complications (0.8%) that did not require revision, including 3 dislocations treated with closed reduction, 2 fractures, 3 nerve injuries, and 1 pseudotumor. At 2 to 4 years of follow-up, the revision rate and the major complication rate with the BHR system were similar to those in previous reports of primary THA. Excellent clinical results were observed, but further follow-up is necessary to assess mid- and long-term results with the BHR system in US patients.

A prospective comparative study of cementless total hip arthroplasty and hip resurfacing in patients under the age of 55 years: a ten-year follow-up

The aim of this study was to evaluate the ten-year clinical and functional outcome of hip resurfacing and to compare it with that of cementless hip arthroplasty in patients under the age of 55 years. Between 1999 and 2002, 80 patients were enrolled into the study: 24 were randomised (11 to hip resurfacing, 13 to total hip arthroplasty), 18 refused hip resurfacing and chose cementless total hip arthroplasty with a 32 mm bearing, and 38 insisted on resurfacing. The mean follow-up for all patients was 12.1 years (10 to 14). Patients were assessed clinically and radiologically at one year, five years and ten years. Outcome measures included EuroQol EQ5D, Oxford, Harris hip, University of California Los Angeles and University College Hospital functional scores. No differences were seen between the two groups in the Oxford or Harris hip scores or in the quality of life scores. Despite a similar aspiration to activity pre-operatively, a higher proportion of patients with a hip resurfacing were running and involved in sport and heavy manual labour after ten years. We found significantly higher function scores in patients who had undergone hip resurfacing than in those with a cementless hip arthroplasty at ten years. This suggests a functional advantage for hip resurfacing. There were no other attendant problems.

The effect of osteoarthritis on the regional anatomical variation of subchondral trabecular bone in the femoral head

BACKGROUND

The subchondral trabecular bone is located deep inside the articular cartilage, with the subcapital region carrying up to 70% of the diurnal loads occurring in the hip joint. This leads to severe regional anatomical variations of subchondral trabecular bone in the femoral head and the purpose of this study was to examine whether osteoarthritis affects these topographic characteristics.

METHODS

60 femoral heads were harvested during hip replacement and studied by osteopenetration at 8 pre-defined angles, at a penetration rate of 1mm/s. Twenty-eight of the donors underwent surgery due to osteoarthritis, whereas the remaining were trauma patients with hip fractures. To correlate these measurements to non-invasive data, all specimens were scanned by micro Computed Tomography (μCT) prior to experimentation. A cross-sectional area, perpendicular to the needle penetration pathway, was analyzed and the deviations compared to the recorded osteopenetration energy.

FINDINGS

The experiments revealed significant topographical deviations in the trabeculae. These were more pronounced in the osteoarthritic samples which also required overall higher osteopenetration energy. A notable dependency of the directional bone strength to its cross-sectional characteristics was observed. Although the effect of "gender" on osteopenetration energy was proven to be significant, gender was not considered an independent variable in a regression model correlating osteopenetration energy to 2D trabecular bone density as this did not improve the value of the adjusted R(2).

INTERPRETATION

The investigation provided refined insight into femoral head load-bearing capacity of patients suffering from osteoarthritis, as a comparison of osteoarthritic to healthy samples illustrated that subchondral trabecular bone in the femoral head region is subjected to increased remodeling and demineralization, reflected in higher osteopenetration values.

Cement applicator use for hip resurfacing arthroplasty

We compared the manufacturer recommended cementing technique for a femoral hip resurfacing implant (BHR, S&N) to a newly designed cement applicator on 20 porous carbon foam specimens. Substantial design changes and improvements of the cement applicator were necessary: The diameter and number of the cement escaping holes at the top of the applicator were optimized for medium viscosity cement. It was necessary to add four separate air inlet holes with large diameters. The inner shape of the applicator had to be adapted to the BHR design with a circular extending chamfer in the proximal region, a parallel inner wall and a second chamfer distally. The interface temperatures showed no risk for heat necrosis using both techniques. The cement penetration depth was more uniform and significantly reduced for the applicator cementing technique (4.34 ± 1.42 mm, 6.42 ± 0.43 mm, p = 0.001). The cement-applicator showed no cement defects compared to a large defect length (0.0 ± 0.0 mm, 10.36 ± 1.10 mm, p < 0.001) with the manufacturer recommended cementing technique. The cement applicator technique appears to be effective for a homogenous cement distribution without cement defects and safe with a lower risk of polar over-penetration.

Hip resurfacing arthroplasty in treatment of avascular necrosis of the femoral head

Background

Hip resurfacing is a conservative type of total hip arthroplasty but its use is controversial, especially in patients with osteonecrosis. The aim of this study was analysis of the clinical and radiographic outcomes of hip resurfacing in patients with osteonecrosis.

Material/Methods

Between 2007 and 2008, 30 hip resurfacing arthroplasties were performed due to osteoarthritis secondary to avascular necrosis of femoral head staged as Ficat III and IV.

Patients were qualified to resurfacing arthroplasty when the extent of avascular necrosis using Kerboul’s method was <200° and the angle between avascular necrosis and head-neck junction was >20°. All patients were evaluated clinically and radiologically before and 60 months after the operation.

Results

The mean Harris Hip Score (HHS) score increased from 47.8 to 94.25 (p<0.05). Physical activity level (University of California, Los Angeles activity score – UCLA activity score) improved from 3.7 to 7.55 (p<0.05). No implant migration was observed.

Conclusions

Management of osteonecrosis of the hip with resurfacing arthroplasty seems to be effective in strictly-selected patients.

A case series of 35 hip revisions for adverse reactions to metal debris following Cormet hip resurfacing

The primary aim of this study was to analyse our painful metal-on-metal (MoM) hip resurfacing revisions with evidence of 'adverse reactions to metal debris' (ARMD). In our series of 35 revisions the median whole blood Cobalt levels were 58 nmols/l (range 12-1407 nmols/l), and whole blood Chromium levels were 73 nmols/l (range 2-353 nmols/l). Thirty-four of our 35 patients had abnormal imaging on Ultrasound scanning (USS). The mean histological Campbell grading of ARMD was 4, and ranged from 0-9. The mean Oxford Hip Score (OHS) increased from 19 pre-revision (range 4-46) to 33 post-revision surgery (range 23-47).We found no correlation between the preoperative metal ion levels, and the severity of the disease or the outcome.Pain following hip resurfacing may arise from a number of causes and when groin pain arises in conjunction with abnormal cross sectional imaging we have offered our patients revision surgery regardless of raised metal ions or grossly abnormal imaging, with good results.

The immunobiology of cobalt: demonstration of a potential aetiology for inflammatory pseudotumours after metal-on-metal replacement of the hip

Abnormal wear of cobalt-containing metal-on-metal joints is associated with inflammatory pseudotumours. Cobalt ions activate human toll-like receptor 4 (TLR4), which normally responds to bacterial lipopolysaccharide (LPS) in sepsis. Activation of TLR4 by LPS increases the expression of chemokines IL-8 and CXCL10, which recruit leukocytes and activated T-cells, respectively. This study was designed to determine whether cobalt induces a similar inflammatory response to LPS by promoting the expression of IL-8 and CXCL10. A human monocytic cell line, derived from acute monocytic leukaemia, was treated with cobalt ions and expression of IL-8 and CXCL10 measured at mRNA and protein levels. Cobalt-treated macrophages showed a 60-fold increase in IL-8 mRNA, and an eightfold increase in production of the mature chemokine (both p < 0.001); expression of the CXCL10 gene and protein was also significantly increased by cobalt (both p < 0.001). Experiments were also performed in the presence of CLI-095, a TLR4-specific antagonist which abrogated the cobalt-mediated increase in IL-8 and CXCL10 expression. These findings suggest that cobalt ions induce inflammation similar to that observed during sepsis by the simultaneous activation of two TLR4-mediated signalling pathways. These pathways result in increased production of IL-8 and CXCL10, and may be implicated in pseudotumour formation following metal-on-metal replacement.

Fixation of a Periprosthetic Intertrochanteric Hip Fracture below a Birmingham Hip Resurfacing

This case report involves a 56-year-old female (Mrs X) with a traumatic intertrochanteric hip fracture with subtrochanteric extension below a previous Birmingham hip resurfacing. Periprosthetic fractures following hip resurfacing are usually subcapital and treated with a revision or conservative management. We present an unusual surgical problem with an interesting solution stabilising the fracture using a proximal femoral locking compression plate (LCP). Eight months following surgery the patient is able to walk pain free and there is good fixation and stability.

Hip resurfacing versus total hip arthroplasty: a systematic review comparing standardized outcomes

BACKGROUND

Metal-on-metal hip resurfacing was developed for younger, active patients as an alternative to THA, but it remains controversial. Study heterogeneity, inconsistent outcome definitions, and unstandardized outcome measures challenge our ability to compare arthroplasty outcomes studies.

QUESTIONS/PURPOSES

We asked how early revisions or reoperations (within 5 years of surgery) and overall revisions, adverse events, and postoperative component malalignment compare among studies of metal-on-metal hip resurfacing with THA among patients with hip osteoarthritis. Secondarily, we compared the revision frequency identified in the systematic review with revisions reported in four major joint replacement registries.

METHODS

We conducted a systematic review of English language studies published after 1996. Adverse events of interest included rates of early failure, time to revision, revision, reoperation, dislocation, infection/sepsis, femoral neck fracture, mortality, and postoperative component alignment. Revision rates were compared with those from four national joint replacement registries. Results were reported as adverse event rates per 1000 person-years stratified by device market status (in use and discontinued). Comparisons between event rates of metal-on-metal hip resurfacing and THA are made using a quasilikelihood generalized linear model. We identified 7421 abstracts, screened and reviewed 384 full-text articles, and included 236. The most common study designs were prospective cohort studies (46.6%; n = 110) and retrospective studies (36%; n = 85). Few randomized controlled trials were included (7.2%; n = 17).

RESULTS

The average time to revision was 3.0 years for metal-on-metal hip resurfacing (95% CI, 2.95-3.1) versus 7.8 for THA (95% CI, 7.2-8.3). For all devices, revisions and reoperations were more frequent with metal-on-metal hip resurfacing than THA based on point estimates and CIs: 10.7 (95% CI, 10.1-11.3) versus 7.1 (95% CI, 6.7-7.6; p = 0.068), and 7.9 (95% CI, 5.4-11.3) versus 1.8 (95% CI, 1.3-2.2; p = 0.084) per 1000 person-years, respectively. This difference was consistent with three of four national joint replacement registries, but overall national joint replacement registries revision rates were lower than those reported in the literature. Dislocations were more frequent with THA than metal-on-metal hip resurfacing: 4.4 (95% CI, 4.2-4.6) versus 0.9 (95% CI, 0.6-1.2; p = 0.008) per 1000 person-years, respectively. Adverse event rates change when discontinued devices were included.

CONCLUSIONS

Revisions and reoperations are more frequent and occur earlier with metal-on-metal hip resurfacing, except when discontinued devices are removed from the analyses. Results from the literature may be misleading without consistent definitions, standardized outcome metrics, and accounting for device market status. This is important when clinicians are assessing and communicating patient risk and when selecting which device is most appropriate for individual patients.

Acetabular component thickness does not affect mid-term clinical results in hip resurfacing

BACKGROUND

The benefits of using thin acetabular components for hip resurfacing have been shown in terms of bone conservation, but there currently are little data available in the literature addressing the mid-term clinical results of these devices.

QUESTIONS/PURPOSES

We aimed to determine whether thinner acetabular components altered mid-term postoperative clinical scores, complication rates, survivorship, radiographic appearance, and metal ion levels.

METHODS

Two hundred eighty-one patients with unilateral disease received a 5-mm thick acetabular shell and 223 received a 3.5-mm shell. The femoral component implanted in both groups was identical. We compared clinical scores, complication rates, survivorship, radiographic results, and ion levels between these two groups.

RESULTS

UCLA hip scores were similar (pain, p = 0.0976; walking, p = 0.9571; function, p = 0.9316; activity, p = 0.2085). Complications were higher in the 5-mm group (6.4% versus 1.8%, p = 0.0431). Both groups were similar regarding survivorship (p = 0.3181), cup radiolucency at 5 years (p = 0.107), and metal ion levels (cobalt p = 0.404, chromium p = 0.250).

CONCLUSIONS

With comparable mid-term clinical results, there is no tangible reason to abstain from using the 3.5-mm acetabular component.

LEVEL OF EVIDENCE

Level III, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.

Hip resurfacing arthroplasty at a non-specialist centre

INTRODUCTION

Few studies have reported the outcome of hip resurfacing arthroplasty (HRA) with respect to implant characteristics from non-specialist centres. We report the survival, clinical and radiological outcomes of a single surgeon series of HRA with an average follow-up duration of five years.

METHODS

All consecutive HRAs performed by a single surgeon between 2003 and 2011 at a district general hospital were retrospectively examined clinically and radiologically.

RESULTS

A total of 85 patients underwent 109 HRAs (58 male [53.2%] and 51 female patients [46.8%]) with a mean follow-up period of 62 months (range: 12-102 months). The median age was 57 years (range: 25-75 years). The mean acetabular and femoral head component sizes were 54 mm (range: 48-64 mm) and 48 mm (range: 42-58 mm) respectively with a mean acetabular inclination angle of 42.9° (range: 20-75°). The survival rate was 95% with five revisions due to aseptic loosening (n=3) and fracture (n=2): these were predominantly for female patients (n=4), with significantly smaller mean acetabular (51 mm, p=0.04) and femoral (44 mm, p=0.02) implant sizes. Furthermore, they had a higher mean acetabular inclination angle of 48.1° (p=0.74). The mean Oxford hip score was 43.8 (range: 25-48) and the mean University of California Los Angeles (UCLA) activity score was 6.8 (range: 3-10). Radiological findings included heterotopic ossification in 13 (11.9%), radiolucent lines in 6 (5.5%), femoral neck thinning in 2 (1.8%) and femoral neck notching in 5 patients (4.6%).

CONCLUSIONS

We have shown that HRA at a non-specialist centre has short to medium-term outcomes comparable with those at specialist centres. HRA therefore remains a viable option although vigilance is required in case selection and follow-up according to national guidance.