Clinical Outcome of the Metal-on-Metal Hybrid Corin Cormet 2000 Hip Resurfacing System : An up to 11-Year Follow-Up Study

This report extends the follow-up for the largest center of the first multicenter US Food and Drug Administration investigational device exemption study on metal-on-metal hip resurfacing arthroplasty up to 11 years. A single surgeon performed 373 hip resurfacing arthroplasties using the hybrid Corin Cormet 2000 system. The Kaplan-Meier survivorship at 11 years was 93% when revision for any reason was used as an end point and 91% if radiographic failures were included. The clinical results demonstrate an acceptable failure rate with use of this system. Loosening of the cemented femoral components was the most common source of failure and occurred at all follow-up intervals. A learning curve that persisted for at least 200 cases was confirmed. All femoral neck fractures occurred before 6 months postoperatively.     

Comparison of Bone Removed During Total Hip Arthroplasty With a Resurfacing or Conventional Femoral Component : A Cadaveric Study

We sought to examine the amount of bone removed during total hip arthroplasty with a resurfacing femoral component, compared to with a conventional, stemmed femoral component, by using 6 male and 4 female cadaveric pelves with attached bilateral proximal femora. Using randomized assignment and order, a total hip arthroplasty with a resurfacing femoral implant was performed on one side, and total hip arthroplasty with a cementless, stemmed femoral implant was performed on the contralateral side. The relationship between native femoral head diameter and the implanted acetabular socket was on average within 2 mm for both procedures. No significant difference was observed in the amount of acetabular bone removed (9.8 g for hip resurfacing vs 8.8 g). However, a resurfacing component resulted in approximated 3 × less bone removal from the femur (25.8 g vs 75.1 g). This study shows that the preservation of femoral bone with a resurfacing femoral component does not result in an increased removal of acetabular bone when compared to the use of a conventional, stemmed femoral component.     

Sciatic Nerve Injury in Total Hip Resurfacing : A Biomechanical Analysis

The condition of the gluteal sling was a significant factor in determining the pressure experienced by the sciatic nerve during acetabular exposure in total hip resurfacing via a posterior approach. The position of the knee did not play a significant role at this stage of the procedure. Average pressures were not elevated above a predefined injury level during positioning for femoral preparation. During hip reduction, knee positioning seemed to play a significant role in pressures placed on the sciatic nerve. These findings suggest that releasing the gluteal sling during a posterior approach for total hip resurfacing may help to prevent postoperative sciatic nerve palsies. Consideration should also be given to at least partially flexing the knee during hip reduction in this procedure.     

The Birmingham Hip Resurfacing Prosthesis : An Independent Single Surgeon's Experience at 7-Year Follow-Up

An independent single surgeon's 7-year experience with Birmingham hip resurfacing is presented. The study also involved investigation of the significance of pedestal sign in patients requiring revision. A consecutive 117 hips in 101 patients (59 male and 42 female patients) operated on by the senior author (VGJ) were assessed at a mean follow-up of 7 years (range, 5-9.4 years). Mean age at surgery was 54 years (range, 20-74 years). Seventy-three hips had a preoperative diagnosis of primary osteoarthritis, and secondary osteoarthritis was seen in 44 hips. Failure was defined as revision for any reason. Revision of the femoral component alone was undertaken in 8 hips (6.8%): 5 within first year for periprosthetic fracture neck of femur and in 3 hips after 5 years of follow-up. In 2 patients who were known to have osteonecrosis of the femoral head preoperatively, the femoral component progressively collapsed into varus after 5 years of follow-up. Pedestal sign was the earliest radiologic sign noted in these 2 patients and progressed rapidly within 1 year on serial radiographs well before the onset of clinical symptoms. Kaplan-Meier survival with revision as end point at 7 years was 91.5% (95% confidence interval, 97.6%-85.4%).     

Hip Resurfacing With the Biomet Hybrid ReCap-Magnum System: 7-Year Results

The purpose of this study was to report our clinical outcome of a large series of metal-on-metal hip resurfacing arthroplasty (HRA) using the hybrid Biomet ReCap-Magnum system. This is a single-designer surgeon series with an average of 5 ± 1 years. Seven hundred forty consecutive hybrid HRAs were performed in 653 patients. Kaplan-Meier survivorship with any revision as an end point was 96.4% at 7 years. Twenty-five (3.4%) cases were revised: 8 due to acetabular component loosening, 6 due to femoral neck facture, 4 due to failure of femoral component fixation, 2 due to deep infection, 2 due to adverse wear, 1 due to psoas tendonitis, 1 due to recurrent dislocation, and 1 due to unexplained pain. Biomet ReCap and Magnum HRA components with hybrid fixation methods showed excellent survivorship for a minimally selected young patient cohort at 7 years.     

Computer Navigation vs Conventional Mechanical Jig Technique in Hip Resurfacing Arthroplasty : A Meta-Analysis Based on 7 Studies

The studies on the accuracy of femoral component in hip resurfacing arthroplasty with the help of computer-assisted navigation were not consistent. This study aims to assess at the functional outcomes after computer navigation in hip resurfacing arthroplasty by systematically reviewing and meta-analyzing the data, which were searched up to December 2011 in PubMed, MEDLINE, EMBASE, MetaMed, EBSCO HOST, and the Web site of Google scholar. Totally, 197 articles about hip resurfacing arthroplasty were collected; finally, 7 articles met the inclusion criteria and were included in this meta-analysis (520 patients with 555 hip resurfacing arthroplasty). The odds ratio for the number of outliers was 0.155 (95% confidence interval, 0.048-0.498; P < .003). In conclusion, this meta-analysis suggests that the computer-assisted navigation system makes the femoral component positioning in hip resurfacing arthroplasty easier and more precise.     

Squeaking Hip Arthroplasties : A Tribological Phenomenon

The clinical incidence of squeaking has been reported with increasing frequency, with ceramic-on-ceramic bearings seemingly most affected. This study investigated potential causes of squeaking in hard-on-hard hip bearings through 2 sets of experimental conditions. Bearing clearance appeared to affect the incidence of squeaking in metal-on-metal surface arthroplasties. The addition of third-body particles to the interface for total hip arthroplasties also affected the incidence of squeaking. In both studies, the incidence of squeaking correlated well with elevated friction. The findings of this study suggest that a likely cause of squeaking in the hip arthroplasty is adverse tribological conditions caused by suboptimal lubrication. There are numerous factors that may cause the suboptimal lubrication, and therefore, it is unlikely that an individual cause for squeaking will be identified.     

A Painful Metal-on-Metal Total Hip Arthroplasty : A Diagnostic Dilemma

Infection, loosening, osteolysis, or other causes can lead to the development of pain about a previously well-functioning total hip arthroplasty. An inflammatory reaction unique to metal on metal arthroplasty can lead to a painful total hip. A synovial biopsy is needed to make this specific diagnosis, and included in the differential diagnosis is infection. The workup of infection includes obtaining a C-reactive protein and erythrocyte sedimentation rate. Elevations of both the C-reactive protein and erythrocyte sedimentation rate are felt to indicate possible infection. This case report describes both of these findings and the treatment rendered in a painful subluxing metal-on-metal total hip arthroplasty presenting with ongoing pain and a large effusion.     

Femoral Neck Fracture After Birmingham Hip Resurfacing Arthroplasty : Prevalence,Time to Fracture,and Outcome After Revision

A consecutive cohort of 3076 Birmingham Hip Resurfacings from a single institution was analyzed. The prevalence of femoral neck fracture, the time to fracture, and the outcome after revision were investigated. Fractures occurred in 34 hips (prevalence, 1.1%). Median time to fracture was 0.27 year (range, 0.014-11.2 years). Mean operation time for revision was 59 minutes, and 71% underwent isolated femoral component revision. At a mean follow-up of 5.5 years since revision, 3 patients required re-revision (2 aseptic loosening, 1 for sepsis) giving a survival of 95.7% (confidence interval, 86.9%-100%) at 5 years for the revision. Median Oxford Hip Score was 12.5% (interquartile range, 3.2%-32.3%). There were no cases of radiologic failure during follow-up. Most fractures occur early after hip resurfacing and were straightforward to revise.     

Arthrodesis of the Hip and Conversion to Total Hip Arthroplasty : A Systematic Review

A systematic review of the literature was performed in order to evaluate the outcomes following arthrodesis of the hip and subsequent conversion to total hip arthroplasty. Eight studies regarding primary hip arthrodesis evaluating 249 hips revealed variable union rates (37.5%–100%) and patient satisfaction rates (69%–100%). Adjacent joint pain was commonly seen in the lower back (up to 75%) and ipsilateral knee (up to 57%) and complications were reported in 8.4%. Eleven studies regarding conversion arthroplasty evaluating 579 patients revealed inconsistent results regarding relief of pain. Complications were seen in up to 54%, most commonly due to mechanical failure, deep infection and nerve palsy. Whilst hip arthrodesis can provide pain relief and patient satisfaction, conversion arthroplasty is associated with an unacceptably high complication rate.     

“Asymptomatic” Pseudotumors After Metal-on-Metal Hip Resurfacing Arthroplasty : Prevalence and Metal Ion Study

Symptomatic abnormal periprosthetic soft-tissue reactions (“pseudotumors”) have been reported after metal-on-metal hip resurfacing arthroplasty (MoMHRA). The aims of this study were (1) to determine the prevalence of asymptomatic pseudotumors after MoMHRA and (2) to measure metal ion levels in these patients. A total of 201 hips in 158 patients were evaluated at a mean follow-up of 61 months (range, 36-88) using ultrasound/magnetic resonance imaging and serum/hip aspirate cobalt and chromium measurements. Pseudotumors found in 7 patients (4%) were associated with significantly higher cobalt and chromium levels and inferior functional scores. Elevated levels of cobalt and chromium ions suggest that pseudotumors are associated with increased wear generated from metal-on-metal articulations. Clinicians need to be aware of pseudotumors as a differential diagnosis during clinical evaluation of MoMHRA patients, and further imaging such as ultrasound or magnetic resonance imaging is recommended to confirm the diagnosis.     

National Trends in Primary Total Hip Arthroplasty in Extremely Young Patients : A Focus on Bearing Surface Usage

The purpose of this study was to present national trends in primary total hip arthroplasty (THA) and bearing surface usage for patients 30 years and younger. Using the Healthcare-Cost-and-Utilization-Project Nationwide Inpatient Sample for the years 2006 to 2009, 8919 primary THA discharges (4454 coded by bearing surface) were identified in patients 30 years and younger. The most commonly used bearing surface was metal-on-metal (MoM), representing 37.6% of cases, followed by ceramic-on-ceramic (CoC) (24.6%), metal-on-polyethylene (MoP) (22.1%) and ceramic-on-polyethylene (15.7%). From 2006 to 2009, the percentage of THAs that used hard-on-hard bearing surfaces decreased (MoM: 42.9%-29.4%; CoC: 34.0%-19.7%).This decrease in hard-on-hard bearing surface usage presents a challenge for surgeons treating young patients to find other acceptable durable bearings that do not have the potential problems associated with MoM or CoC.     

Two-Stage Exchange for Infected Resurfacing Arthroplasty : Use of a Novel Cement Spacer Technique

Infection after total hip arthroplasty is a devastating complication. A 2-stage reimplantation with antibiotic-impregnated interval spacer is typically recommended. We present a case of infected resurfacing hip arthroplasty treated with a novel cement spacer technique. The aim was to avoid the introduction of the infection into the femoral medullary canal with the use of a conventional stemmed antibiotic cement spacer. Reimplantation was accomplished routinely, and the patient remains infection-free at 9 months.     

Interprosthetic Fractures of the Femur : Treatment With a Single-Locked Plate

Interprosthetic fractures of the femur, those between an ipsilateral hip and knee arthroplasty, are challenging to treat secondary to limited bone available for fixation, osteopenic bone, a compromised intramedullary blood supply, and an often elderly patient population. From 2002 to 2006, 22 consecutive patients with an interprosthetic femur fracture were treated with a single-locking plate. Follow-up averaged 17.7 months, with fracture union achieved an average of 13.8 weeks postoperatively. All patients regained their preoperative ambulatory status and subjectively reported unchanged function of their hip and knee arthroplasties. Single-locked plating is an effective method of treatment of interprosthetic fractures of the femur. Emphasis on preservation of the soft tissue envelope and sufficient cortical purchase both above and below the fracture is of paramount importance.     

Joint Replacement Access in 2016 : A Supply Side Crisis

Demand for primary and revision arthroplasty is expected to double in 10 years. Coincident with this is a decreased interest in arthroplasty by residents. Retirement of arthroplasty surgeons further threatens access. This study determines if supply will meet demand. Survey data were used to calculate the 2016 workforce. Demand in 2016 was estimated using the Nationwide Inpatients Sample. Between 2008 and 2016, 400 arthroplasty specialists and 1584 generalists will enter the workforce. By 2016, 1896 arthroplasty surgeons will retire using 65 years as a conservative retirement age, whereas 4239 will retire using 59 years as a baseline retirement age. In 2016, the model estimated a procedural shortfall ranging from 174?409 (↓18.6%) using conservative retirement assumptions (age, 65 years) to 1?177?761 (↓69.4%) using baseline retirement assumptions (age, 59 years). This economic model predicts a supply side crisis that threatens patient access to specialty care. Immediate steps to stimulate supply must be taken.     

Bulk Femoral Head Autograft Without Decortication in Uncemented Total Hip Arthroplasty : Seven- to Ten-Year Results

Superolateral acetabular bone defect is a serious challenge in uncemented total hip arthroplasty for acetabular dysplasia. We report a bulk bone autografting technique without decortication of the acetabulum and femoral head contact surfaces in 22 joints. Mean follow-up time was 8.3 years, and survival rates were 100% for loosening and revision end points. The preoperative Japanese orthopedic association hip score increased from 49.5 to 94.0. Although trabecular bridging and graft remodeling occurred in all cases, complete trabecular reorientation was observed in only 15 joints. Eccentric polyethylene wear was observed in 8 of 22 joints, and osteolysis, in 1 joint. Our technique is easy to perform, and midterm results were favorable; thus, we conclude that it may be an effective option for bulk bone autografting.     

Hip Flexion After Birmingham Hip Resurfacing : Role of Cup Anteversion,Anterior Femoral Head-Neck Offset,and Head-Neck Ratio

We aimed to investigate the factors affecting range of flexion after hip resurfacing. A total of 82 cases, operated by a single surgeon, were assessed at a mean of 43 months. The Einzel-Bild-Roentgen-Analysis for the acetabular cup software was used to measure socket orientation. Range of flexion had a moderate positive correlation with cup anteversion (R = 0.26, P = .017), weak but significant negative correlation with neck diameter (R = −0.23, P = .042), and none with anterior femoral head-neck offset. Using multivariate analysis that adjusted for age, sex, cup anteversion and inclination, head-neck offset ratio, head-neck ratio, and neck diameter, the only significant correlate of flexion was cup anteversion (P = .017). Care should be taken during cup placement to allow adequate anteversion to be maintained in Birmingham hip resurfacing because this can affect flexion range of motion.     

Retroperitoneal Hematoma : An Unusual Cause of Pain After Total Hip Arthroplasty

Pain following total hip arthroplasty due to impingement of the iliopsoas is a recognized complication of the procedure with a reported incidence as high as 4.3%. The pain is most often due to direct mechanical irritation of the iliopsoas due to a malpositioned or oversized acetabular cup. Definitive treatment of iliopsoas impingement often requires surgical revision or iliopsoas tenotomy, although many cases remain undiagnosed or are managed conservatively. We present an unusual case of pain after total hip arthroplasty due to a large retroperitoneal hematoma secondary to acetabular cup irritation of the iliopsoas tendon. This case represents a potentially important complication of undiagnosed or conservatively managed iliopsoas impingement, particularly in patients taking anticoagulants or antiplatelet medications.     

Large-Diameter Modular Metal-on-Metal Total Hip Arthroplasty : Incidence of Revision for Adverse Reaction to Metallic Debris

Large-diameter modular metal-on-metal (MOM) total hip arthroplasty (THA) may offer reduction in wear debris and improved stability. Four studies are summarized here that used a large-diameter modular MOM system. A total of 1076 THAs were performed. This article presents data from 779 of these THAs with minimum 2-year follow-up (mean, 4.2 years) or revision since index THA (21 hips, with 1 more pending). Overall survivorship at 2 years was 98.6%; at 5 years, it was 97.0%. Seven revisions for an adverse reaction to metallic debris (ARMED), and 1 additional pending revision for ARMED, showed marked variability in presenting symptoms and intraoperative and postoperative findings. Data show good clinical performance of the modular MOM system, but suggest that surgeons must be diligent in monitoring MOM THA patients and aggressive in diagnosing and revising patients with a potential ARMED.     

Clinical Outcome,Survival and Polyethylene Wear of an Uncemented Total Hip Arthroplasty : A 10- to 12-Year Follow-Up Study of 81 Hips

A complete 10- to 12-year follow-up of an uncemented total hip arthroplasty (THA) was performed regarding survival, clinical outcome, polyethylene wear and influencing factors on wear. Seventy-two patients (75 Mallory Head uncemented THA) with primary osteoarthritis operated on in 1999 or 2000 were included in the survival study. Mean age at the time of operation was 57.9 years (range 37–70). The survival rate after 11.9 years was 96% (95% CI 0.89–1.01). In three cases the acetabular component was revised because of extensive polyethylene wear. Fifty-four patients with 57 THAs were available for clinical and radiological analysis. At a mean follow-up time of 10.7 years (range 10–12) the clinical outcome can be considered comparable to other uncemented THA. Mean polyethylene wear was 1.8 mm (range 0.4–3.8) with an annual wear rate of 0.15 mm/y. There was a significant correlation between polyethylene wear and inclination of the cup as well as male gender.