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.     

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.     

Characterization of Progression of Pelvic Osteolysis After Cementless Total Hip Arthroplasty : Computed Tomographic Study

A retrospective analysis of 63 primary total hip arthroplasty cases was done using repeated computed tomography scans to evaluate the pelvic osteolytic lesions in early stage. The progression rate of osteolysis of hips with small osteolytic volume less than 766.97 mm³ in initial CT was 85.82 mm³/year, and that of hips with osteolysis more than 766.97 mm³ was 456.3 mm³/year (P < 0.001). Younger patients less than 52 years old with good Harris Hip Scores (more than 80) frequently showed much faster progression in volume of osteolytic lesions. The rate of osteolysis was accelerated when the amount of osteolysis reached a certain threshold volume in active young patients in a cascade manner even in early stage.     

Total Hip Arthroplasty Using Imageless Computer-Assisted Hip Navigation: A Prospective Randomized Study

In a prospective randomized study of two groups of 65 patients each, we compared the acetabular component position when using the imageless navigation system compared to the freehand conventional technique for cementless total hip arthroplasty. The position of the component was determined postoperatively on computed tomographic scans of the pelvis. There was no significant difference for postoperative mean inclination (P = 0.29), but a significant difference for mean postoperative acetabular component anteversion (P = 0.007), for mean deviation of the postoperative anteversion from the target position of 15° (P = 0.02) and for the outliers regarding inclination (P = 0.02) and anteversion (P < 0.05) between the computer-assisted and the freehand-placement group. Our results demonstrate the importance of imageless navigation for the accurate positioning of the acetabular component.     

Highly Cross-Linked Polyethylene in Total Hip Arthroplasty for Osteonecrosis of the Femoral Head : A Minimum 5-Year Follow-Up Study

We evaluated 162 hips with osteonecrosis of the femoral head that had undergone THA using highly cross-linked polyethylene liner after a minimum follow-up of 5 years. Neither femoral nor acetabular components displayed radiographic evidence of mechanical loosening or osteolysis, and no components had been revised at the latest follow-up. The mean rate of linear liner wear was 0.038 mm/year. Univariate regression analysis did not demonstrate that age, gender, weight, activity level or cup inclination had any influence on penetration. While the long term effects of altered mechanical properties of highly cross-linked PE remain unknown, the clinical and radiographic results at a minimum of 5 years are promising for this high-risk population.     

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.     

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.     

Primary Total Hip Arthroplasty With Duraloc Cup in Patients Younger Than 50 Years : A 5- to 7-Year Follow-Up Study

We evaluated the clinical and radiographic results of 67 (64 patients) cementless Duraloc-300 cups for young active patients after a mean follow-up period of 6.2 years. The preoperative mean Harris hip score improved from 46.24 to 96.5 points at 5 years. The survivorship of the cup, using radiographically confirmed aseptic loosening as the end point, was 100% at 5 years. The mean rate of liner wear was 0.125 mm/y (00-0.39 mm/y). Acetabular osteolysis was found in 14% (9 hips) of the 67 hips, and the osteolysis is related to polyethylene wear (P = .0024) and sex (P = .001). Although there was no aseptic loosening of the components, there was a high rate of liner wear of the polyethylene liner and acetabular osteolysis.     

Total Hip Arthroplasty For Femoral Neck Fracture : Comparing In-Hospital Mortality,Complications, and Disposition to an Elective Patient Population

Patients treated with total hip arthroplasty (THA) for osteoarthritis (OA) and femoral neck fracture (FNF) between 1990–2007 were compared using the National Hospital Discharge Survey (NHDS). In-hospital, post-operative complications and disposition were compared at six-year intervals to establish trends over time. A total of 2,160,061 THAs were performed for OA, while 174,641 were performed for FNF. Peri-operative mortality and pulmonary embolism rates following elective THA were lower at each interval when compared to THA performed for FNF (P < 0.001). Hematomas, infections, and dislocations were also higher in the traumatic group. The FNF group showed improvements with respect to mortality and rates of pulmonary embolism, infection, and dislocation over time. During the most recent interval, there was no difference in dislocation rates between the two groups. The length of stay and the percentage of patients discharging to a rehab facility were significantly higher in the FNF group at each time interval.     

Effect of Zoledronic Acid on Reducing Femoral Bone Mineral Density Loss following Total Hip Arthroplasty : Preliminary Results of a Prospective Randomized Trial

This randomized trial evaluated the effect of zoledronic acid on femoral bone mineral density (BMD) following primary total hip arthroplasty. Bone mineral density was compared for up to 2 years in 27 patients receiving 5 mg zoledronic acid intravenous infusion and in 24 patients receiving placebo at 2 weeks and 1 year after surgery. Zoledronic acid prevented loss of bone mineral density at 1 year (+ 13.8% vs + 1.4%, P = .0065) and 2 years (+ 14.3% vs − 4.0%, P < .0001) in Gruen zone 1, at 1 year (− 8.4% vs − 25.4%, P < .0001) and 2 years (− 9.6% vs − 27.3%, P < .0001) in Gruen zone 7, at 6 weeks, 6 months, and 1 or 2 years in Gruen zones 4 and 6. For all Gruen zones, prevention of BMD loss by ZOL was significant at 6 weeks, 6 months, 1 year (+ 0.80% vs − 6.03%, P < .0001) and 2 years (-0.16% vs − 7.13%, P < .0001).     

Metal-on-Metal vs Conventional Total Hip Arthroplasty : A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Metal-on-metal (MOM) hip articulations represent a potential alternative to conventional metal-on-polyethylene total hip arthroplasty (THA). We performed a systematic review of the peer-reviewed literature in search of studies comparing MOM with conventional primary THA with regard to functional outcomes, radiographic outcomes, and complication rates. Four Level I randomized controlled trials remained following our screening process. The data published in these studies were extracted and aggregated using a Mantel-Haenszel cumulative fixed effects meta-analysis. We found no significant difference between MOM and conventional THA with regard to functional outcomes as measured by Harris hip scores and radiographic outcomes as measured by radiolucent lines. Patients with MOM THA did however demonstrate a 3.37 times greater complication rate (1.57, 7.26). In light of the lack of superiority, the increased complication rate, the greater cost, and the potential for adverse medical consequences associated with MOM THA, these bearing surfaces should be used with caution.     

“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.     

Revision Total Hip Arthroplasty Using a Modular Tapered Stem With Distal Fixation : Good Short-Term Results in 125 Revisions

After 2 to 7 years we reviewed 125 prosthetic hip arthroplasty stem revisions using a modular tapered stem with distal fixation. Median age of these patients was 68 (33-92) years. Baseline and follow-up data were registered prospectively according to the Danish Hip Arthroplasty Registry. Survival, free of any rerevision, was 94%. Harris Hip Score improved from average 44 to 85. Bony regeneration was an early and significant finding in most cases. Complications included 4 (3%) fractures intraoperatively and 8 (6%) dislocations, 4 (3%) deep infections, and 1 (1%) stem fracture. This modular taper system is very versatile, can be used in most femoral revision cases, and allows rapid bone remodeling. We did not find an increased number of complications compared to the literature. Further long-term follow-up, however, is essential.     

Revision Total Knee Arthroplasty for Component Malrotation is Highly Beneficial : A Case Control Study

Component malrotation is a recognized cause of post total knee arthroplasty (TKA) pain. We reviewed 24 patients who had TKA revision due to component malrotation as the only objective abnormality. Mean combined component rotation was 6.8° excessive internal rotation, as documented by computed tomography. Twenty-four matched control patients had TKA revision due to aseptic loosening. Mean follow-up was 37 months. Preoperative Knee Society Score improved by 49 points at 6 months postoperatively for the malrotation patients and by 39 for the loosening patients. At last follow-up, Knee Society Score was 80 for the malrotation group and 75 for the loosening group. We recommend the use of computed tomography scans in evaluation of all patients with early painful TKAs and no objective evidence of infection. When component malrotation is demonstrated, early revision should be considered.     

The 6-Year Migration Characteristics of a Hydroxyapatite-Coated Femoral Stem : A Radiostereometric Analysis Study

A prospective cohort of 30 patients undergoing primary total hip arthroplasty for treatment of osteoarthritis was enrolled in a study to characterize the migration behavior of a clinically successful cementless stem. At 6 years, the mean subsidence of the stem was 0.63 mm (range, −0.33 to 3.68 mm); the mean rotation into retroversion was 1.41° (range, −1.33° to 7.48°). No stems had additional subsidence of more than 0.25 mm between 6 months and 6 years. The resultant mean subsidence between 2 and 6 years was 0.03 mm, which is below the limit measurable by radiostereometric analysis. The data demonstrate that subsidence of this cementless stem occurs within the first 6 months, after which there is persistent stabilization.     

The Cementless Anatomic Benoist Girard (ABG) II Total Hip Arthroplasty : A Minimum 8-Year Follow-Up Study

We have evaluated 90 consecutive primary cementless ABG II total hip replacements. The bearings combined metal-on-polyethylene in 64 hips, and alumina-on-alumina in 26 hips. At the minimum 8-year follow-up, ten patients had died, seven had been lost to follow-up, two had undergone revision of either or both components, and 68 were still alive and had not been revised. With revision for any reason as the endpoint, the cumulative survival rate at 10 years was 97.5% ± 1.7%, and 98.7% ± 1.3% for the metal-back cup and the femoral component, respectively. No hip showed peri-acetabular osteolysis. The ABG II total hip arthroplasty has demonstrated favourable clinical and radiological outcomes as well as survival in the current series. Further follow-up is needed to confirm these mid-term results.     

Adjustable Cutting Blocks for Computer-Navigated Total Knee Arthroplasty : A Cadaver Study

Computer-navigation in total knee arthroplasty has been reported to increase accuracy but also procedure duration. We compared surgical time and precision using a novel adjustable cutting block vs freehand navigation with conventional blocks on 12 bilateral cadaver tibiae. The mean time required was significantly less to position the adjustable block than the conventional block (2 minutes 10 seconds vs 6 minutes 35 seconds, P = .006). Guide positioning precision (standard deviation) for the adjustable block vs conventional block was as follows: varus/valgus, 0.24° vs 1.16° (P = .015); posterior slope, 0.35° vs 0.74° (P = .13); and cut height, 0.37 vs 1.41 mm (P = .010). There were no significant differences in the final bone cut accuracy between the 2 groups. The use of adjustable cutting blocks simplifies navigated procedures and may reduce the time required to perform a navigated total knee arthroplasty.     

Bilateral Total Joint Arthroplasty : The Early Results from the New Zealand National Joint Registry

This study evaluated the mortality rate, major complications, and early outcomes of single anesthetic bilateral total hip and knee arthroplasty compared with unilateral and staged procedures. A total of 37 828 total hip and knee arthroplasties were evaluated with 6-month Oxford 12 scores. Major complications and mortality rates were recorded. Analysis of variance tables were used for statistical analysis. The single anesthetic bilateral group were significantly younger (P < .001), with their age-adjusted postoperative Oxford 12 scores significantly better (P < .001) than the other 2 groups. The surgeons involved, in general, performed more than 25 total knee and hip arthroplasties per year. There was 1 death within the first 6 months occurring in the staged bilateral group and was unrelated to the surgery. The complication rate as reported by patients was low in all groups, and there was no significant difference. The results show that, in selected patients, single anesthetic bilateral total knee or hip arthroplasty is a safe, low-risk procedure with very good patient-generated outcome scores at 6 months when performed by an experienced surgeon.     

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.     

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.