Acetabular revisions using trabecular metal cups and augments

The purpose of this study is to evaluate the efficacy of trabecular metal (TM) shells and augments in acetabular revisions with significant pelvic bone loss. We retrospectively reviewed 97 cases of consecutive loose total hip arthroplasty with a minimum of Paprosky grade IIA pelvic bone loss treated with a TM revision acetabular component with or without modular augments. The average Harris hip score improved from 55 preoperatively to 76 postoperatively. At the most recent radiographic evaluation, 88 cups demonstrated no lucent lines, 1 cup had lucent lines but remained well fixed, and 8 cups underwent resection arthroplasty for infection. One cup was revised for chronic instability. There were no aseptic failures in this series. Trabecular metal acetabular cups and shells with or without the use of modular augments can be effectively used to revise failed acetabular components in patients with substantial pelvic bone loss.

Gains and losses of small incision lateral total hip arthroplasty: what the patients want and its index case result

OBJECTIVE

A poll was initially attempted to elucidate what type of skin incision would be preferred by the patients. The retrospective analysis of index cases was preformed to reveal the gains and losses of small incision transgluteal THA.

MATERIALS AND METHODS

We performed a poll on the preferred type of skin incision to the patients, their families and the medical personnel in orthopedic department in a face-to-face manner. According to the result of the poll, we changed approaches from a standard transgluteal to a small incision transgluteal approach. Each 20 consecutive index patients that underwent standard or small-incision transgluteal THA were followed and compared for more than 2 years.

RESULTS

The small incision THA group showed more rapid mobilization, shorter hospital stay, and better early satisfaction. However, no clinical benefits of small incision were observed after 6-weeks postoperatively. There were significant variations in implant alignments. More early major complications such as dislocation, intraoperative femoral fracture or leg length inequalities occurred in the small incision group.

CONCLUSIONS

The use of a small incision in THA resulted in subtle and temporary gains, at the cost of several major early complications. Now we perform THA with definitely smaller incision than before but we do believe that performing a stable and well-aligned THA is far more important than the length or amount of surgical dissection.

A comparison between total hip replacement for osteonecrosis and degenerative joint disease

There has been some reluctance to perform total hip replacement on younger patients with osteonecrosis because of the poor results reported in the earlier literature. To determine the extent to which advances in surgical technique and prosthesis design have led to improved results, we evaluated 203 total hip replacements performed for osteonecrosis and compared them to 300 performed for degenerative joint disease. The failure rate for all femoral and acetabular components combined was 3.7% (22 of 600), in degenerative joint disease and 10.1% (41 of 406) in osteonecrosis. However, results with the most recently used acetabular component, the noncemented HGP-1, were markedly improved over earlier components in both conditions, with only 1 failure in 235 hips (0.4%). The increased survivorship of THR in osteonecrosis with improved component design and surgical technique is encouraging. Total hip replacement is a good option for patients with advanced stages of osteonecrosis, and similar surgical indications should be used for patients with degenerative joint disease and other disorders.

Clinical applications of oxidized zirconium

Total joint arthroplasty is being performed in younger, more active patients, which necessitates improved implant longevity and enhanced component performance. Over the past decade, there has been an increased focus on alternative bearing materials as a potential solution to these issues. Historically, cobalt-chromium has been the material of choice as a bearing surface for both the femoral component in total knee arthroplasty (TKA) and the femoral head articulation in total hip arthroplasty (THA). In recent years, oxidized zirconium (OxZr) has been introduced as a bearing surface with superior resistance to surface roughening, improved frictional characteristics, and excellent biocompatibility as compared with cobalt-chrome. This article demonstrates the use of OxZr as an alternate bearing in the setting of TKA, THA, and hip hemi-arthroplasty based on its biomaterial properties as it applies to polyethylene and native cartilage surface articulation.

Determining lesion size in osteonecrosis of the femoral head

BACKGROUND

Several studies have documented that the size of the osteonecrotic lesion in the femoral head is an essential parameter in determining prognosis and treatment. There are several methods currently available to measure lesion size, but no general agreement as to which is most useful. In the present study, three different radiographic methods for determining lesion size were evaluated and compared.

METHODS

Anteroposterior and lateral radiographs of forty-two hips with osteonecrosis were examined. The extent of osteonecrotic involvement of the femoral head was determined through the use of three different methods: the volume of necrosis by quantitative digital image analysis, and the angular measurements described by Kerboul et al. and Koo and Kim. Graphs were constructed to demonstrate these relationships.

RESULTS

Volumetric measurement appeared to be the most reliable. There was only a rough correlation with angular measurements. Several sources of error were noted when simple angular measurements of irregular, three-dimensional lesions were used. The Kerboul method routinely overestimated lesion size and designated 81% of the lesions as "large." The modified Koo and Kim method provided a more even distribution of lesion size and correlated with volumetric measurements in 74% of hips (thirty-one of forty-two hips).

CONCLUSIONS

Quantitative volumetric measurements appear to be the most reliable method to measure the true size of a three-dimensional osteonecrotic lesion of the femoral head. Volumetric measurement is more accurate than angular measurement and can be performed easily with modern technology. Angular measurements, although somewhat simpler to use than volumetric measurements, may provide only a rough estimate of lesion size, partly due to the considerable differences in outline or location of the necrotic segments. Nevertheless, determination of lesion size must be part of a comprehensive system of staging of this disease, which includes the evaluation of other parameters, such as the extent and degree of articular surface involvement and the status of the hip joint and the acetabulum.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Comparison of fluorodeoxyglucose positron emission tomography and (111)indium-white blood cell imaging in the diagnosis of periprosthetic infection of the hip

We aimed to compare the accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET) with technetium-99m sulfur colloid (111)indium-labeled white blood cell scintigraphy (TcSC-Ind BM/WBC) in diagnosis of periprosthetic infection. Eighty-nine patients with 92 painful hip prostheses were recruited prospectively and given the option of undergoing either combined FDG-PET and TcSC-Ind BM/WBC or FDG-PET only. FDG-PET correctly diagnosed 20 of the 21 infected cases (sensitivity, 95.2%) and ruled out infection in 66 of the 71 aseptic hips (specificity, 93%) corresponding to a positive predictive value of 80% (20/25) and a negative predictive value of 98.5% (66/67). TcSC-Ind BM/WBC correctly identified 5 of the 10 infected cases (sensitivity, 50%) and 39 of 41 aseptic cases (specificity, 95.1%) corresponding to a positive and negative predictive values of 41.7% (5/12 cases) and 88.6% (39/44 cases), respectively. Based on these preliminary results, FDG-PET appears to be a promising diagnostic tool for distinguishing septic from aseptic painful hip prostheses.

Impaction allografting for massive femoral defects in revision hip arthroplasty using collared textured stems

We present a prospective study of impaction grafting using collared textured stems in femurs with massive defects (defined as requiring >150 cm(3) of cancellous allograft). Eighteen hips were followed for a minimum of 2 years. Average Harris hip scores increased from 50 preoperatively to 83 at most recent follow-up. Seventeen hips were functioning well at the time of most recent follow-up and exhibited no stem subsidence or aseptic loosening. One hip was associated with visible subsidence and required further revision. Single-photon emission computed tomography analyses performed at an average of 37 months indicated active graft reorganization in all cases studied. Impaction allografting with collared textured stems for massive defects demonstrates good intermediate-term clinical results and may be a useful alternative to allograft stem composites and megaprostheses.

Ceramic-on-ceramic versus ceramic-on-polyethylene bearings in total hip arthroplasty: Results of a multicenter prospective randomized study and update of modern ceramic total hip trials in the United States

One reason why otherwise well-functioning total hip replacements have a finite service life is eventual aseptic loosening of the implants because of osteolysis induced by wear particles from the artificial bearing. Pain and osteolysis from wear debris can manifest even in the absence of aseptic loosening. Total hip replacements with ceramic-on-ceramic articulations have shown less wear both in vitro and in vivo. A randomized prospective clinical trial was conducted to compare the outcomes of ceramic-on-ceramic articulations to ceramic-on-polyethylene articulations. Two-year data are of interest because premature failures of ceramic femoral heads usually occur by this time interval. Of 500 patients enrolled in this trial, half received total hip replacements with alumina-on-alumina bearings, while the other half had ceramic-on-polyethylene bearings. At the two-year follow-up, 444 patients (217 study group and 227 control group) were available for review. The clinical and radiographic outcomes between the groups were comparable, and reflected the typical results of primary total hip replacements. No complications related to spontaneous failures of the ceramic bearings were observed at this early follow-up period. Further follow-up is needed to confirm these findings over the long-term, but the short-term safety of alumina ceramic bearings in hip replacements reported in other recent reports is further validated by our findings. (Hip International 2005; 15: 129-35).

Hemoglobin substitutes

Orthopaedic patients frequently require blood transfusions to treat peri-operative anemia. Research in the area of hemoglobin substitutes has been of great interest since it holds the promise of reducing the reliance on allogeneic blood transfusions. The three categories of hemoglobin substitutes are (1) cell-free, extracellular hemoglobin preparations made from human or bovine hemoglobin (hemoglobin-based oxygen carriers or HBOCs); (2) fluorine-substituted linear or cyclic carbon chains with a high oxygen-carrying capacity (perfluorocarbons); and (3) liposome-encapsulated hemoglobin. Of the three, HBOCs have been the most extensively studied and tested in preclinical and clinical trials that have shown success in diminishing the number of blood transfusions as well as an overall favorable side-effect profile. This has been demonstrated in vascular, cardiothoracic, and orthopaedic patients. HBOC-201, which is a preparation of cell-free bovine hemoglobin, has been approved for clinical use in South Africa. These products may well become an important tool for physicians treating peri-operative anemia in orthopaedic patients.

Alternative bearing surfaces in total hip arthroplasty

Polyethylene wear and extension of indications of total hip arthroplasty into younger and younger age groups have pushed manufacturers to develop more durable bearing surfaces. Standard polyethylene, the plastic used for the first 3 decades of hip replacement, virtually ceases to exist in its original form. Modifications of the processing, including sterlization in an inert environment and cross-linking, have demonstrated some improvements in wear. Hard-on-hard bearings such as ceramic-on-ceramic and metal-on-metal also have demonstrated extremely low wear. This article reviews the pros and cons of the alternative bearing options available to assist in the proper bearing selection for a particular patient.

Regulation of BMP-induced transcription in cultured human bone marrow stromal cells

BACKGROUND

Adherent bone marrow stromal cells are inducible osteoprogenitors, giving rise to cells expressing osteoblast markers including alkaline phosphatase, osteopontin, osteocalcin, and bone sialoprotein. However, the potency of inducers varies in a species-specific manner. Glucocorticoids such as dexamethasone induce alkaline phosphatase activity in both human and rat mesenchymal stem cells, while mouse bone marrow stromal cells are refractory to dexamethasone-induced alkaline phosphatase activity. In contrast, BMP induces alkaline phosphatase activity in both mouse and rat bone marrow stromal cells, while BMP effects on human bone marrow stromal cells are poorly characterized.

METHODS

Bone marrow samples were isolated from patients undergoing hip replacement. Mononuclear marrow cells were cultured and grown to confluence without or with 10 (-7) M dexamethasone. Cells from each isolate were passaged into medium containing 100 micro g/mL ascorbate phosphate and treated with dexamethasone, 100 ng/mL BMP, or no inducer. At day 6, alkaline phosphatase activity was assayed, and RNA was prepared for mRNA analyses by real-time polymerase chain reaction.

RESULTS

Bone marrow stromal cells from twenty-four of twenty-six patients showed no significant osteogenic response to BMP-2, 4, or 7 as determined by alkaline phosphatase induction. However, BMPs induced elevated levels of other genes associated with osteogenesis such as bone sialoprotein and osteopontin as well as BMP-2 and noggin. If primary cultures of human bone marrow stromal cells were pretreated with dexamethasone, BMP-2 treatment of first-passage cells induced alkaline phosphatase in approximately half of the isolates, and significantly greater induction was seen in cells from males. Dexamethasone treatment, like BMP treatment, also increased expression of the BMP-binding protein noggin.

CONCLUSIONS

Most human femur bone marrow stromal cell samples appear incapable of expressing elevated alkaline phosphatase levels in response to BMPs. Since BMP treatment induced expression of several other BMP-regulated genes, the defect in alkaline phosphatase induction is presumably not due to impaired BMP signaling. We hypothesize that the mechanism by which BMPs modulate alkaline phosphatase expression is indirect, involving a BMP-regulated transcription factor for alkaline phosphatase expression that is controlled differently in humans and rodents.

Persistent non-specific FDG uptake on PET imaging following hip arthroplasty

Hip arthroplasty is a common surgical procedure, but the diagnosis of infection associated with hip arthroplasty remains challenging. Fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) has been shown to be a promising imaging modality in settings where infection is suspected. However, inflammatory reaction to surgery can result in increased FDG uptake at various anatomic locations, which may erroneously be interpreted as sites of infection. The purpose of this study was to assess the patterns and time course of FDG accumulation following total hip replacement over an extended period of time. Firstly, in a prospective study nine patients with total hip replacement were investigated to determine the patterns of FDG uptake over time. Three FDG-PET scans were performed in each patient at about 3, 6 and 12 months post arthroplasty. Secondly, in a retrospective analysis, the medical and surgical history and FDG-PET imaging results of 710 patients who had undergone whole-body scans for the evaluation of possible malignant disorders were reviewed. The history of arthroplasty and FDG-PET findings in the hip region were reviewed for this study. Patients with symptomatic arthroplasties or related complaints during FDG-PET scanning were excluded from the analysis. During the entire study period, all nine patients enrolled in the prospective study were demonstrated to have increased FDG uptake around the femoral head or neck portion of the prosthesis that extended to the soft tissues surrounding the femur. Among the patients reviewed in the retrospective study, 18 patients with a history of 21 hip arthroplasties who were asymptomatic at the time of FDG-PET scan met the criteria for inclusion. The time interval between the hip arthroplasty and the FDG-PET study ranged from 3 months to 288 months (mean+/-SD: 80.4+/-86.2 months). In 81% (17 of 21) of these prostheses, increased FDG uptake could be noted around the femoral head or neck portion of the prosthesis. The average time interval between arthroplasty and FDG-PET scan in these patients was 71.3 months. In only four prostheses (19%, 4 of 21) was no abnormally increased FDG uptake seen around the prostheses or adjacent sites. The average time interval in these patients was 114.8 months. It is concluded that following hip arthroplasty, non-specifically increased FDG uptake around the head or neck of the prosthesis persists for many years, even in patients without any complications. Therefore, to minimize the number of false-positive results for infection with PET studies obtained to evaluate a painful hip prosthesis, caution should be exercised when interpreting FDG uptake around the head or neck portion of the prosthesis.

The use of impaction grafting in revision total knee arthroplasty

Impaction grafting has been used successfully in revision total knee arthroplasty. Histology and preliminary clinical results show that this technique may be useful in situations in which bone loss is extensive. In contrast to bulk allografts, morcellized graft remodels and incorporates with the host. The preliminary results and technique are reviewed briefly.

Early failure of precoated femoral components in primary total hip arthroplasty

BACKGROUND

In an effort to decrease the rate of aseptic loosening, certain cemented femoral components were designed to have a roughened or textured surface with a methylmethacrylate precoating. Reports differ as to whether this step has increased or decreased the rate of failure. This study was designed to evaluate this issue.

METHODS

Five hundred and fourteen hips treated with a cemented Harris Precoat stem (Zimmer, Warsaw, Indiana) were evaluated clinically and radiographically and compared with 254 hips treated with an uncoated Harris Design-2 stem (Howmedica, East Rutherford, New Jersey). Prostheses that had been removed at revision were examined. The cementing and surgical techniques were identical and the population demographics were similar for these two groups.

RESULTS

The mean durations of follow-up were 8.4 and 13.5 years for the Precoat and uncoated Design-2 stems, respectively. At those times, at least forty-nine (9.5%) of the 514 Precoat components and at least ten (3.9%) of the 254 uncoated Design-2 stems had failed (p = 0.006). Five Precoat stems fractured, and no uncoated Design-2 stems fractured. Component failure was associated with use in young, active, heavy men with a diagnosis of avascular necrosis and generally with the use of smaller components. The cementing technique was satisfactory in the majority of the patients, and there were no qualitative differences in cementing technique between the hips that failed and those that did not. The mechanisms of failure of the Precoat prostheses included bone-cement loosening, focal osteolysis, stem fracture, and prosthesis-cement debonding. Fractures of smaller components occurred as a result of fatigue failure and were associated with good distal fixation but proximal stem loosening.

CONCLUSIONS

The rate of failure of roughened, precoated, cemented femoral components was considerably higher and occurred earlier than that of femoral components that were neither textured nor precoated with methylmethacrylate. Younger patients with avascular necrosis had a higher risk of failure; however, this factor alone did not completely explain the differences in outcome between these two components. The causes of aseptic loosening are multifactorial and may be related to component design and size as well as to precoating and surface finish.

Independent contribution of elevated-rim acetabular liner and femoral head size to the stability of total hip implants

The use of an elevated-rim acetabular liner in total hip arthroplasty is widely accepted. We sought to determine quantitatively the amount of additional stability provided by the elevated-rim liner compared with the standard nonelevated liner. The stability of the hip with a 32-mm femoral head was compared with the standard 28-mm head. Our results show that a 15 degrees elevated-rim acetabular liner placed in the posterior quadrant increased hip stability by an additional 8.9 degrees of internal rotation. Similarly the 32-mm head provided 8.1 degrees of additional internal rotation. The increases were statistically significant (P<.0001). We did not encounter increased anterior dislocation intraoperatively. The findings of this study indicate that the 32-mm head may contribute to hip stability in primary total hip arthroplasty, and in instances in which a posterior approach is used, an elevated-rim liner placed in the posterior quadrant may contribute independently to hip stability.

Prevertebral abscess with extension into the hip joint

We present a case of a paravertebral abscess with extension into the hip joint. The presumed conduit of infection in this case is the iliopsoas bursa, which has been shown to provide direct communication between the retroperitoneal space and the hip joint in up to 15% of cadaveric specimens. The patient was treated with emergent open irrigation and debridement of the hip joint, as well as percutaneous drainage of the prevertebral abscess. The patient remains minimally symptomatic at the 2-year follow-up.

The promising role of 18F-FDG PET in detecting infected lower limb prosthesis implants

The purpose of this study was to evaluate the feasibility of using 18F-FDG and PET for the detection of infection associated with lower limb arthroplasty.

METHODS

Seventy-four prostheses in 62 patients in whom infection was suspected after artificial hip or knee placement were studied with this technique. Images were obtained 60 min after an intravenous injection of FDG. The images were interpreted as positive for infection if tracer uptake was increased at the bone-prosthesis interface. A final diagnosis was made by surgical exploration or clinical follow-up for 1 y. PET results were compared with the follow-up outcome in all patients.

RESULTS

The sensitivity, specificity, and accuracy of PET for detecting infection associated with knee prostheses were 90.9%, 72.0%, and 77.8%, respectively. The sensitivity, specificity, and accuracy of PET for detecting infection associated with hip prostheses were 90%, 89.3%, and 89.5%, respectively. Overall, the sensitivity was 90.5% and the specificity was 81.1% for detection of lower limb infections.

CONCLUSION

FDG PET is a useful imaging modality for detecting infections associated with lower limb arthroplasty and is more accurate for detecting infections associated with hip prostheses than for detecting infections associated with knee prostheses.

Modern ceramic-on-ceramic total hip systems in the United States: early results

In 1997, two manufacturers began Food and Drug Administration approved investigations of a ceramic-on-ceramic (alumina) articulation total hip replacement in the United States. Osteonics (Allendale, NJ) and Wright Medical Technology (Arlington, TN) enrolled more than 500 and 300 patients, respectively, when their studies ended in the middle part of 1998. The author presents detailed early results of the series by Wright Medical Technology. Three hundred thirty-three patients were enrolled in 11 centers around the country in a prospective series. All patients received the Transcend ceramic-on-ceramic articulation and have a minimum of 18 months followup with a range of 18 to 36 months. Harris hip scores increased on average from 44 to 97 points. Four patients underwent revision surgery; one for deep infection, one for early migration of the cup, one for dislocation, and one for liner malplacement. Overall, there were 42 complications. Seven were systemic and 35 were related to the total hip replacement. Four of the 35 complications were ceramic related and included three chipped liners and one eccentric seating of the cup liner. To date, no patient underwent revision surgery for aseptic loosening. Seven technical guidelines are suggested to enhance the quality of the intraoperative and postoperative results: a conservative femoral neck cut; horizontal cup placement (< 45 degrees); increased anteverted cup placement (> 20 degrees); use of trial liners; impaction of ceramic pieces; hand placement of the liner; and removal of osteophytes and/or part of the anterior wall of the acetabulum to avoid impingement. Alternate bearing articulations, particularly ceramics, have important technical aspects to be considered at the time of implantation to minimize intraoperative and postoperative complications. To date, there have been no postoperative fractures of the ceramic pieces in any of the completed or ongoing ceramic-on-ceramic investigations by all involved manufacturers. These preliminary results are satisfactory at this time. One can look to the future with cautious optimism.

Predonated autologous blood transfusions after total knee arthroplasty: immediate versus delayed administration

Efforts to avoid complications associated with transfusion of allogeneic blood have increased the use of preoperatively donated autologous blood (PAB). A major controversy has arisen: Should the same criteria be used for transfusion of autologous as allogeneic red cells? This study prospectively and randomly compared giving PAB immediately after total knee arthroplasty (TKA), beginning in the recovery room or delaying a transfusion until the patient's hemoglobin had fallen to less than a 9.0 g/dL transfusion trigger point. The results show that patients who received immediate transfusion had fewer nonsurgical complications (P < .002). Because TKAs are associated with an average blood loss of 1,400 mL, we recommend that PAB be used in the immediate postoperative period, especially in the elderly, in whom the risk for cardiac or nonsurgical complications is inherently increased.

Revision total hip arthroplasty in patients with avascular necrosis

This retrospective study compared the results of revision total hip arthroplasty (THA) in patients with avascular necrosis to patients with osteoarthritis. Twenty-two revision THAs (34 components) in 19 patients with avascular necrosis were compared with 35 revision THAs (55 components) in 31 patients with osteoarthritis. All of the procedures were performed by a single surgeon between 1981 and 1994, and all patients had a minimum of 2 years of follow-up. At the time of revision surgery, the average age was 54 years for the avascular necrosis patients and 67 years for the osteoarthritis patients (P=.002). Clinical and radiographic follow-up was performed for an average of 7 years (range: 2-12 years). Six (18%) components in the avascular necrosis group and nine (16%) components in the osteoarthritis group required re-revision for aseptic loosening an average of 7 years after the original revision (range: 2-11 years). Statistical analysis demonstrated no significant difference between the two groups in regard to the incidence of failure, time to failure, Harris Hip Score, and radiographic appearance. Contrary to expectations derived from the literature on primary THA, no difference was found between the outcome and survivorship of revision THA in patients with avascular necrosis and patients with osteoarthritis, despite a significant difference in age.

Total hip arthroplasty in patients with avascular necrosis of the femoral head: a 2- to 10-year follow-up

One hundred twenty-three total hip arthroplasties were performed in 85 patients with osteonecrosis of the femoral head. There were 51 males and 34 females with an average age of 45 years. The average followup time was 4.6 years with a range of 2 to 10 years. All femoral stems and 71 sockets were fixed with acrylic cement. Fifty-two of the sockets used were placed without cement. The average Harris hip score improved from 45 points preoperatively to 92 points at the time of last followup. Of the 246 components used, 6 acetabular and 4 femoral prostheses in 7 patients have been revised (4%). Two components (0.8%) were revised for infection, 2 (0.8%) for repeated dislocation, and 6 (2.5%) for aseptic loosening. There is current radiographic loosening in 3 acetabular and 2 femoral components (2%). None of the noncemented acetabular components was either radiographically loose or revised. Within the subset of the 36 patients (52 hips) with a minimum 5-year followup (average, 6.6 years), 5 components (5%) were revised and 4 (4%) components are radiographically loose. The overall revision rate for cemented and hybrid hips at 2 to 10 years followup was 4%. The revision rate for hybrid hips alone was 2.5% in the entire series and 2% for hips with a minimum followup of 5 years. These results seem significantly better than previously reported. Using modern cement techniques and components, total hip arthroplasty can give excellent results in the young patient with avascular necrosis and may be the treatment of choice when reconstructive surgery is required.