Geode of the femur: an uncommon manifestation potentially reflecting the pathogenesis of rheumatoid arthritis

Geodes are noted frequently in rheumatoid arthritis (RA), but large geodes of the femur are uncommon. We describe a patient with RA and a large geode in his femur; histological findings were consistent with a rheumatoid nodule and chronically inflamed synovium. We review the literature of large femoral geodes and what this particular manifestation may reflect about the pathogenesis of RA.

The natural history of asymptomatic osteonecrosis of the femoral head in adults with sickle cell disease

BACKGROUND

Osteonecrosis of the femoral head is a frequent complication in adult patients with sickle cell disease. However, little is known about the natural history of asymptomatic lesions.

METHODS

One hundred and twenty-one patients (121 hips) with sickle cell disease and asymptomatic osteonecrosis of the femoral head that was contralateral to a hip with symptomatic osteonecrosis were identified with magnetic resonance imaging between 1985 and 1995. The lesions were graded with use of the Steinberg classification system. The patients were followed with annual plain radiographs. The mean duration of follow-up was fourteen years.

RESULTS

At the time of the initial evaluation, fifty-six hips were classified as Steinberg stage 0, forty-two hips were classified as Steinberg stage I, and twenty-three hips were classified as Steinberg stage II. At the time of the most recent follow-up, pain had developed in 110 previously asymptomatic hips (91%) and collapse had occurred in ninety-three hips (77%). Symptoms always preceded collapse. Of the fifty-six hips that were classified as Steinberg stage 0 at the time of the initial evaluation, forty-seven (84%) had symptomatic osteonecrosis and thirty-four (61%) had collapse at the time of the most recent follow-up. Of the forty-two asymptomatic stage-I hips, forty (95%) became symptomatic within three years and thirty-six (86%) had collapse of the femoral head. Of the twenty-three asymptomatic stage-II hips, all became symptomatic within two years and all collapsed; the mean interval between the onset of pain and collapse was eleven months. At the time of the final follow-up, ninety-one hips (75%) had intractable pain and required surgery.

CONCLUSIONS

Untreated asymptomatic osteonecrosis of the femoral head in patients with sickle cell disease has a high likelihood of progression to pain and collapse. Because of the high prevalence of complications after total hip arthroplasty in patients with this disease, consideration should be given to early surgical intervention with other procedures in an attempt to retard progression of the disease.

Computed tomographic evaluation of component position on dislocation after total hip arthroplasty

True proper position after total hip arthroplasty was determined by measuring the cup and stem anteversion using computed tomography. We compared 20 dislocated hips (14 posterior and 6 anterior) with 18 non-dislocated hips. Both the cup anteversion and the stem anteversion showed no differences among the groups. The sum of cup and stem anteversion in posterior dislocated hips was significantly lesser than that in non-dislocated hips and the sum in anterior dislocated hips was significantly greater than that in non-dislocated hips. These results suggested even if the cup alone or the stemalone is at proper position, dislocation might occur.

Functional pelvic orientation measured from lateral standing and sitting radiographs

We prospectively obtained preoperative and 3-month postoperative lateral pelvic radiographs in the standing and sitting positions from 84 patients who underwent total hip arthroplasty. We measured pelvic orientation (flexion extension) using the anterior pelvic plane as defined by the anterior superior iliac spines and pubic tubercles as references. There was a trend towards upright pelvic alignment when standing, with a mean anterior pelvic plane angle of 1.2 degrees (range, -22 degrees - +27 degrees). In the sitting position the pelvis tended to extend posteriorly, with a mean anterior pelvic plane angle of -36.2 degrees (range, -64 degrees - +4 degrees). There was a wide variation in the arc of pelvic flexion extension as patients moved from standing to sitting, with are of pelvic motion in some patients as mobile as 70 degrees and in others as stiff as 5 degrees. There was no significant variation between males and females or between preoperative and postoperative pelvic flexion extension. There were substantial variations in pelvic orientation when comparing standing and sitting for an individual patient and between different patients. This variation can be unpredictable, and may influence implant alignment and stability after total hip arthroplasty.

Surgical treatment of displaced femoral neck fractures in the elderly: a survey of the American Association of Hip and Knee Surgeons

A survey was distributed to the American Association of Hip and Knee Surgeons (AAHKS) membership to evaluate surgical treatment preferences for displaced femoral neck fractures (DFNFXs). Of 718 members, 381 (54%) responded to the 16-question survey that was an adjunct to a multicenter, randomized study (funded by AAHKS/OREF) designed to prospectively evaluate efficacy of hemiarthroplasty vs total hip for treatment of DFNFXs. Hemiarthroplasty (85%) was the most preferred treatment option for DFNFXs (reduction with internal fixation 2%, total hip arthroplasty 13%). Prefracture hip pain/osteoarthritis, poor bone quality, and fracture comminution were the main reasons why arthroplasty was chosen over reduction with internal fixation. Ambulatory status and dislocation risk after arthroplasty were the main factors in choosing between unipolar (48%) and bipolar (52%) hemiarthroplasty. Total hip arthroplasty is used by 88% of responders. Dislocation risk and ambulatory status were influential factors against performing total hip arthroplasty. Arthroplasty is the preferred method of surgical intervention for the treatment of DFNFXs for AAHKS members.

The effect of spinal anesthesia on blood transfusion rate in total joint arthroplasty

BACKGROUND

Total joint arthroplasty (TJA) patients often receive allogeneic blood transfusion. The use of regional anesthesia (RA) is thought to protect against the need for blood transfusion, but many randomized trials of RA in TJA have not reached this conclusion unanimously. We sought to describe the effect of RA on allogeneic transfusion in a large retrospective TJA series.

METHODS

We examined data from all TJAs performed in Edmonton, Alberta, in the year 2000 (n = 1875) and used logistic regression modelling to determine the relation between the use of RA and allogeneic transfusion.

RESULTS

Twenty-eight percent of TJA subjects received an allogeneic transfusion. Transfusion was independently associated with increasing age, decreasing body mass, decreasing preoperative hemoglobin, female sex, increased comorbidity and prolonged operative time. After controlling for these factors, we found that the use of RA (in the form of spinal anesthesia) compared with general anesthesia reduced the odds ratio (OR) for transfusion to 0.729 (95% confidence interval [CI] 0.559-0.949). This represents the combination of a strong relation between RA and transfusion prevention in hip arthroplasty (OR 0.646, 95% CI 0.443-0.944) and a nonsignificant relation in knee arthroplasty (OR 0.825, 95% CI 0.564-1.208).

CONCLUSION

The use of spinal anesthesia protects against allogeneic transfusion in arthroplasty of the hip but not the knee. This is consistent with what is known about the hemodynamic consequences of spinal anesthesia.

Fast track in total hip and knee arthroplasty--experiences from Hvidovre University Hospital, Denmark

This study investigated whether unselected patients operated on with total hip arthroplasty (THA) or total knee arthroplasty (TKA) could accomplish a self-developed accelerated track, ANORAK-HH, with a planned length of stay (LOS) of maximum 5 days and patient satisfaction at all parts of the track. 307 patients who sustained 329 hip and knee arthroplasties were included in the study with the main material constituted from 243 primary unilateral THA and TKA arthroplasties. ANORAK-HH includes pre-operative patient clinic, patient motivation, dedicated staff, unchanged criteria for discharge and a planned LOS of maximum 5 days. 22 patient characteristics and 11 satisfaction parameters were registered as well as readmissions within 3 months. 95% of patients had a LOS of maximum 5 days with a mean of 3.9 days. Median and mean values of satisfaction for the entire track were 10 and 9.4 out of 10, respectively. Participation in patient clinic did not influence LOS or satisfaction. Operations at the beginning of the week and lack of blood transfusion were associated with shorter LOS. Finally, ANORAK-HH could be effectively accomplished in unselected THA and TKA patients without having an adverse effect on patient readmission rate.

The value of anteroposterior pelvic radiographs for evaluating pelvic osteolysis

We investigated the role of conventional radiographs and computed tomography scans for the routine followup of total hip arthroplasty patients. Among 92 total hip arthroplasties with a mean followup of 8.5 years, 94 acetabular lesions were detected among 63 hips using computed tomography and 42 of these hips had osteolysis diagnosed on radiograph. Using computed tomography as a gold standard, the sensitivity of anteroposterior pelvic radiographs for the detection of acetabular osteolysis was 67% and the specificity was 72%. Although smaller lesions were more frequently missed, osteolysis was diagnosed on radiograph in 20 of 22 total hip arthroplasties with lesion volumes of at least 10 mL. Because larger osteolytic lesions were generally detected on radiograph, two-dimensional and three-dimensional lesion sizes correlated. However, the limits of agreement for the volume estimates based on the radiograph area were -14.6 to 18.7 mL. Although radiographs can be useful to screen for clinically important pelvic osteolysis, computed tomography images are necessary to accurately measure lesion volumes.

Improved preoperative iron status assessment by soluble transferrin receptor in elderly patients undergoing knee and hip replacement

A poor preoperative haemoglobin (Hb) status is frequently encountered among adult patients scheduled for corrective surgery of the locomotive system, representing the main risk factor for blood transfusion. The soluble transferrin receptor (sTfR) has become a highly specific parameter for the detection of iron deficits as it can differentiate between iron deficiency anaemia and anaemia of chronic disease, because of the lack of effect by associated inflammation, unlike ferritin. The objectives of this study were to evaluate patients with the prevalence of risk for transfusion, the effect of inflammation on ferritin (F) values and functional iron deficiency in elderly patients with advanced degenerative arthropathy scheduled for hip or knee replacement. This observational, prospective study included patients over 50 years, operated for hip or knee replacements between April and June 2004. Of 218 patients studied, 87 (39%) presented with Hb levels between 10 and 13 g/dl. The prevalence of functional iron deficit was 27% (sTfR > 1.76 mg/l), while only 8.6% of patients displayed F levels below normal. As expected, C-reactive protein levels were elevated in 24.8% of patients and erythrocyte sedimentation rate was elevated in 50%. These inflammatory markers did not correlate with levels of either F or sTfR. Multiple factors can affect F levels, such as the inflammatory status of osteoarthritis in the elderly, obesity, nonsteroidal anti-inflammatory drugs therapy and low physical performance. As sTfR is not affected by inflammation, it has emerged as a primary parameter for the evaluation of iron status during preoperative assessment among patients scheduled for arthroplasty surgery. Our data strongly suggest that sTfR measurement contributes to improve patient management.

Massive retroperitoneal hematoma during enoxaparin treatment of pulmonary embolism after primary total hip arthroplasty: case reports and review of the literature

In light of the increasing use of enoxaparin for both prophylaxis and treatment of thromboembolic disease, the number of potential complications from this anticoagulant will also continue to increase. This article presents the first case of massive retroperitoneal hematoma during enoxaparin treatment of pulmonary embolism after a primary total hip arthroplasty and discusses several unique sequelae of the retroperitoneal hematoma. Retroperitoneal hematomas are often fatal, and treatment involves aggressive fluid resuscitation with possible surgical decompression.

Improved outcome in femoral revision arthroplasty with tapered fluted modular titanium stems

Many techniques have been advanced to achieve reliable femoral stem fixation in revision total hip arthroplasty. In a cross-sectional study, we compared quality of life in 220 patients with two femoral stem designs: a modular tapered and fluted titanium stem design and a cylindrical extensively coated chrome-cobalt stem with single modularity (head size and neck length alone). We matched cohorts based on age decade and gender. The minimum followup was 1 year with a median of 2 years. Subjective outcome assessment and patient satisfaction were measured using the WOMAC Osteoarthritis Index, the Oxford Hip Score, the SF-12, and the Arthroplasty Satisfaction Scale. At followup, all quality of life measures favored the tapered titanium stem. WOMAC pain, function, and overall scores all were higher in this group. The Oxford Hip Score and the Satisfaction score reflected a greater difference in outcome between the two stem designs. We presume reduced stiffness of the titanium stem, coupled with the intraoperative modularity, resulted in the improved patient outcomes observed in this study.

2006 Otto Aufranc Award Paper: significance of in vivo degradation for polyethylene in total hip arthroplasty

Our research group developed an implant retrieval program to study in vivo degradation of polyethylene. We now have evidence to support our hypothesis that degradation of radiation-sterilized polyethylene occurs in the body for not only historical gamma air sterilized liners, but also for conventional gamma inert sterilized (ArCom) and annealed highly crosslinked polyethylene (Crossfire) liners as well. Our research has also led to the discovery that the most severe manifestations of in vivo oxidation typically occur in regions of the liner experiencing minimal wear, such as the rim of the component, where the body fluids (containing oxidizing species) have access to the polyethylene. Our data from historical, ArCom, and Crossfire retrievals all point to a similar scenario in which the femoral head limits the in vivo oxidation of polyethylene at the bearing surface. Consequently, provided rim impingement does not occur, and the polyethylene locking mechanisms remain relatively isolated from oxidizing fluid, in vivo oxidation does not seem to be clinically important in the first 10 years of implantation for conventional gamma sterilized polyethylene. We conclude that in vivo degradation should be included among the list of potential long-term failure modes for modular polyethylene components for total hip arthroplasty.

Multimodal analgesia without routine parenteral narcotics for total hip arthroplasty

Methods for managing pain after a total hip replacement have changed substantially in the past 5 years. We documented the outcome of patients treated with a multimodal pain program designed to avoid parenteral narcotics. Avoidance of parenteral narcotics can essentially eliminate the complications of respiratory depression, ileus, and narcotic-induced hypotension. It can minimize nausea and vomiting which cause dissatisfaction with an operation. Twenty-one of 140 patients (15%) needed parenteral narcotics postoperatively with only nine patients (6.4%) using parenteral narcotics after the day of surgery. Mean pain scores were below 3 of 10 on all postoperative days. There were no patients with respiratory depression or ileus, and four (2.9%) with urinary retention. Nausea occurred with 35 patients (25%) in the recovery room and in 28 patients (20%) thereafter. Emesis occurred in five patients (3.6%) with two incidences in the recovery room. One hundred and thirty-eight patients (98.6%) were discharged home at a mean of 2.7 seven days postoperatively with 98 (70%) on a single assistive device. The multimodal pain management program, which avoided parenteral narcotics, was effective in providing pain relief, nearly eliminating emesis, and eliminating the severe complications of respiratory depression, urinary tract infection and ileus, as well as accelerating function.

Factors affecting survival of uncemented total hip arthroplasty in patients 50 years or younger

Providing a long-lasting total hip arthroplasty for patients younger than 50 years remains one of the greatest challenges for modern arthroplasty surgery. We retrospectively reviewed 221 patients younger than 50 years who underwent 299 uncemented total hip arthroplasties from 1983 to 2000. We assessed 5- to 15-year survival with revision as the endpoint. Femoral stem survival was 99.3% (range, 98.4-100%), 98.9% (range, 97.7-100%), and 96.8% (92.5-100%) at 5, 10, and 15 years, respectively. Including all component designs acetabular survival was 98.7% (range, 97.4-100%), 84.6% (78.8-90.4%), and 52.5% (40.7-64.3%) at 5, 10, and 15 years, respectively. Overall survival was 46.8% (33.5-58.1%) at 15 years. Total hip arthroplasties performed for hip dysplasia had lower 10-year and 15-year survival. Zirconium-on-polyethylene articulations had lower acetabular revision rates compared with cobalt-chrome-on-polyethylene. Sixty-nine revisions were performed, most commonly for polyethylene wear. Uncemented femoral stems resulted in 90% survival at 15 years followup in patients younger than 50 years at index operation. Contemporary bearing surfaces in association with such stems may provide long-lasting total hip arthroplasties, even in young, active patients.

Surgical variables affect the mechanics of a hip resurfacing system

Recent clinical studies have linked failure to surgical variables of stemmed hip resurfacing systems. We used finite element analysis to investigate the effects of implant position, stem orientation, and extent of fixation both on the local stresses and strains associated with implant loosening, neck fracture, and stem fracture, as well as on the load transfer distribution in the bone-implant system. The range of peak stress in the cement was reduced from 11 to 13 MPa for the varus stem to 3.2 to 4.2 MPa for the valgus stem. The range of peak strain in the bone was also reduced from -0.35% to -0.45% strain for the varus stem to -0.19% to -0.27% strain for the valgus stem, but only when reamed cancellous bone remained exposed. Peak stresses in the stem were low for all cases. Additionally, the implant's load transfer distribution was generally insensitive to all variables examined and the femoral head was substantially unloaded. Our data indicate the local stresses and strains associated with implant loosening and neck fracture were reduced by placing the implant in a valgus orientation and covering reamed cancellous bone, but unloading of the femoral head, found for all variables examined, may lead to adverse bone remodeling.

A Multicenter Clinical Study of the Safety and Activity of Maleimide-Polyethylene Glycol–modified Hemoglobin (Hemospan®) in Patients Undergoing Major Orthopedic Surgery

Background

Hemospan (Sangart Inc., San Diego, CA), a polyethylene glycol-modified hemoglobin with unique oxygen transport properties, has successfully completed a phase I trial in healthy volunteers. Because adverse events are expected to increase with age, the authors conducted a phase II safety study of Hemospan in elderly patients undergoing elective hip arthroplasty during spinal anesthesia.

Methods

Ninety male and female patients, American Society of Anesthesiologists physical status I-III, aged 50-89 yr, in six Swedish academic hospitals were randomly assigned to receive either 250 or 500 ml Hemospan or Ringer's acetate (30 patients/group) before induction of spinal anesthesia. Safety assessment included vital signs and Holter monitoring from infusion to 24 h, evaluation of laboratory values, and fluid balance. The hypothesis to be tested was that the incidence of adverse events would be no more frequent in patients who received Hemospan compared with standard of care (Ringer's acetate).

Results

Three serious adverse events were noted, none of which was deemed related to study treatment. Liver enzymes, amylase, and lipase increased transiently in patients in all three groups. There were no significant differences in electrocardiogram or Holter parameters, but there was a suggestion of more bradycardic events in the treated groups. Hypotension was less frequent in the treated patients compared with controls.

Conclusions

In comparison with Ringer's acetate, Hemospan mildly elevates hepatic enzymes and lipase and is associated with less hypotension and more bradycardic events. The absence of a high frequency of serious adverse events suggests that further clinical trials should be undertaken.

Physical therapy alone compared with core decompression and physical therapy for femoral head osteonecrosis in sickle cell disease. Results of a multicenter study at a mean of three years after treatment

BACKGROUND

Osteonecrosis of the femoral head is a common complication in patients with sickle cell disease, and collapse of the femoral head occurs in 90% of patients within five years after the diagnosis of the osteonecrosis. However, the efficacy of hip core decompression to prevent the progression of osteonecrosis in these patients is still controversial.

METHODS

In a prospective multicenter study, we evaluated the safety of hip core decompression and compared the results of decompression and physical therapy with those of physical therapy alone for the treatment of osteonecrosis of the femoral head in patients with sickle cell disease. Forty-six patients (forty-six hips) with sickle cell disease and Steinberg Stage-I, II, or III osteonecrosis of the femoral head were randomized to one of two treatment arms: (1) hip core decompression followed by a physical therapy program or (2) a physical therapy program alone. Eight patients withdrew from the study, leaving thirty-eight who participated.

RESULTS

Seventeen patients (seventeen hips) underwent decompression combined with physical therapy, and no intraoperative or immediate postoperative complications occurred. Twenty-one patients (twenty-one hips) were treated with physical therapy alone. After a mean of three years, the hip survival rate was 82% in the group treated with decompression and physical therapy and 86% in the group treated with physical therapy alone. According to a modification of the Harris hip score, the mean clinical improvement was 18.1 points for the patients treated with hip core decompression and physical therapy compared with 15.7 points for those treated with physical therapy alone. With the numbers studied, the differences were not significant.

CONCLUSIONS

In this randomized prospective study, physical therapy alone appeared to be as effective as hip core decompression followed by physical therapy in improving hip function and postponing the need for additional surgical intervention at a mean of three years after treatment.

Polyethylene sterilization and production affects wear in total hip arthroplasties

Production and package sterilization techniques for the polyethylene used in acetabular components for total hip arthroplasties are known to affect wear. We considered three combinations of techniques: sterilization by radiation in inert gas with isostatically molded polyethylene, in inert gas and ram-extruded polyethylene, and in air with extruded polyethylene. The intent of this study was to confirm that molded polyethylene and polyethylene radiated in inert environments reduce wear rates in vivo, to determine the combination of methods with the least wear, and to determine how much variance in wear is attributable to these methods. We reviewed 150 consecutive total hip arthroplasties done in 133 patients using 28-mm cobalt-chrome femoral heads and polyethylene-lined, titanium, ring-locked acetabular components. The least wear occurred in gamma inert-molded polyethylene components. The mean volumetric wear rates were 52.12 mm3/year for gamma inert-molded, 62.32 mm3/year for gamma inert-extruded, and 66.09 mm3/year for gamma air-extruded polyethylene components. Relative risk assessment found gamma air-extruded and gamma inert-extruded polyethylene components to wear 16% and 11% more than gamma inert-molded polyethylene components, respectively. Gender, body mass index, and age accounted for the greatest amount of the explained variance in volumetric wear (57.5%, 21.6%, and 14.4, respectively), followed by angle of wear (3.4%), and sterilization and production technique (3.2%).

[Computed tomography assessment of incorporation bone grafts after cemented acetabular revision]

The aim of the study was assessment, on the basis of computed tomography (CT) examination, of remodelling of compacted frozen bone sliver grafts used in acetabular revision arthroplasty.

MATERIAL AND METHOD

The study involved ten patients treated in the years 1998-2000 for aseptic loosening of hip joint prosthesis elements. Eight women and two men were studied. The mean age of the patients was 69.6 years (from 52 to 74 years). The mean time between primary and revision arthroplasty was 6.8 years. Spiral CT examination was performed 6 weeks and 3, 6, 12, 24, 36 months after the operation. Density measurement was done using ROI (region of interest) function including spongy bone area from 50 to 80 mm2. The studied layer thickness was 3.2 mm. In the examination both hip joints were assessed, accepting the joint not operated on as standard for a given patient. The measurement was done in six zones according to DeLee, Charnley.

RESULTS

Progressing reduction of graft density was found in relation to healthy bone density. During the first three months most rapid density reduction was observed in all patients. The lowest density decrease was seen in the postero-superior part of the acetabulum while the highest density reduction occurred in the lower part. Trabeculation change was observed from that resembling compact bony tissue to that corresponding to spongy tissue. In two patients after six months a significant graft density reduction occurred both in the lower and upper parts of the acetabulum. In these patients acetabular loosening was confirmed, requiring reoperation.

CONCLUSIONS

CT examination of bone density makes possible quantitative assessment of bone graft remodelling and qualitative assessment imaging the structure of the grafts. The non-invasive method of CT examination of bone graft density allows for prognostication as to stability of the seated acetabulum.

Conversion of failed proximal femoral internal fixation to total hip arthroplasty in osteopetrotic bone

Osteopetrosis is a rare disease. When fractures are encountered, fixation is extremely difficult. A 38-year-old man with osteopetrosis who sustained a displaced Pauwels type IV fracture with 3 failed internal fixations required total hip arthroplasty. Two main problems were perceived during preoperative planning: the removal of failed and broken metalwork and reaming of the tight intramedullary canal to allow seating of the femoral stem. We present technical solutions to aid the surgeon in the management of this difficult type of case using custom-made tungsten carbide instrumentation.

Gluteus maximus flap transfer for greater trochanter reconstruction in revision THA

We evaluated the results of an operative technique used in five patients (five hips) to reconstruct the greater trochanter with a gluteus maximus flap transfer during revision total hip arthroplasty. We exposed the hip through a posterior approach that split the gluteus maximus in its midsubstance. We then raised a flap from the posterior portion of the gluteus muscle that was elevated proximally to create a triangular muscle flap. The flap was sewn into the gap between the greater trochanter and lateral cortex of the femur and secured to the inner surface of the anterior capsule of the hip. With the hip abducted 10 degrees to 15 degrees, the edges of the gluteus maximus were closed over the flap and the greater trochanter. We compared the results of these patients with those of five patients (five hips) who had the trochanter left unrepaired and those of four patients (four hips) who had excision of the greater trochanter and suture closure of the intervening gap. The flap group had less pain, lower incidence of limp and Trendelenburg sign, and less need for support than the other two groups, but range of motion decreased.

Preliminary results of tantalum acetabular components for THA after pelvic radiation

Total hip arthroplasty after previous therapeutic pelvic radiation has been associated with high acetabular component loosening rates. We report 12 total hip arthroplasties performed in 11 patients who had therapeutic pelvic radiation to treat an underlying malignancy. The total hip arthroplasties were performed with porous tantalum trabecular metal acetabular components. No clinical failures occurred at a mean of 31 months followup (range, 24-48 months) and there were no reoperations. Harris hip scores improved from average of 46 points preoperatively to 88 points postoperatively. There was no radiographic evidence of component migration or implant loosening. Five hips had incomplete radiolucencies on immediate postoperative radiographs, and all remained unchanged or regressed on subsequent radiographs. These early clinical and radiographic results with a porous tantalum trabecular metal acetabular component are encouraging, but long-term followup studies are needed to validate durability.

Failure mechanisms of total hip resurfacing: implications for the present

In the past decade, there has been a renewed interest in hip resurfacing due to recent design improvements. It is unclear whether the recent improvements have accounted for all of the previous failure mechanisms. We determined the long-term performance of hip resurfacing, while paying special attention to the mechanisms of failure. We retrospectively reviewed 62 patients (65 hips) who had Indiana conservative hip prostheses implanted between 1977 and 1981. Forty-one of 62 joints had failed, representing a failure rate of 66%. The time to failure averaged 9.7 years with a range of 6 months to 21.5 years. There were 23 femoral failures (37%). Eleven were caused by femoral fracture, and 12 were caused by femoral loosening. All late femoral failures (greater than 10 years postoperatively) showed narrowing of the femoral neck secondary to stress shielding. There were 18 acetabular failures (29%) with 10 failing secondary to polyethylene wear and eight failing secondary to acetabular loosening. Failure of the Indiana conservative hip prosthesis continues over time related to femoral and acetabular failure mechanisms. These data should be considered in the context of growing enthusiasm for resurfacing with new bearing surfaces and cementless fixation.