The acetabulum: a prospective study of three-phase bone and indium white blood cell scintigraphy following porous-coated hip arthroplasty

Although few studies address the use of three-phase bone scanning (TPBS) and indium-111-labeled white blood cell scintigraphy (111In-WBC) in hip arthroplasty utilizing a porous-coated prosthesis, the literature suggests that scintigraphic patterns in the uncomplicated patient may differ form that seen with the cemented prosthesis. In an attempt to determine the scintigraphic natural history, 25 uncomplicated porous-coated hip arthroplasties in 21 patients were prospectively studied with serial TPBS and 111In-WBC at approximately 7 days, and 3, 6, 12, 18, and 24 mo postoperatively. This report deals with findings related to the acetabulum. All 25 prostheses (144 of 144 scans) demonstrated increased uptake on the bone-phase images. Although this activity decreased with time, 76% had persistent uptake at 24 mo. Twenty-three of 25 prostheses (126 of 140 scans) showed increased uptake on 111In-WBC scintigraphy, invariably decreasing with time, but with 37% having significant uptake at 24 mo. Scintigraphic patterns in the uncomplicated porous-coated hip arthroplasty patient appear to differ from patterns described in cemented prostheses.     

Alloarthroplasty of the hip joint. Radiologic diagnosis of loosening and infection in cemented total endoprostheses

Patients with problems following implantation of cemented total hip prostheses must be clinically examined. This examination is followed by a series of diagnostic imaging procedures. These include X-ray diagnosis, 3-phase 99mTc-MDP bone scans, scintigraphy for inflammation, and arthrography, performed singly or as sequential studies. X-ray findings and scintigraphic patterns arousing or confirming a suspicion of aseptic (mechanical) or septic (infectious) loosening of the prosthesis are evaluated and discussed.     

Immunoscintigraphy of septic loosening of knee endoprosthesis: a retrospective evaluation of the antigranulocyte antibody BW 250/183

Immunoscintigraphy with the use of the antigranulocyte antibody BW 250/183 is a reliable method for detecting infection, especially in septic loosening of hip prostheses, for which purpose quantitative interpretation of the time-activity course is employed. Therefore, we retrospectively studied whether similar results could be achieved in knee prostheses. We verified 28 scintigraphic examinations in 26 patients by histology. Scintigraphy was performed during an early (4–6 h post injection) and a late phase (23–25 h post injection). Infection was diagnosed when activity around the knee prosthesis increased by more than 10% compared with bone marrow. We found a sensitivity and a negative predictive value of 100%, a specificity of 80%, a positive predictive value of 81% and an accuracy of 89%. Specificity and accuracy are lower than in the evaluation of hip prostheses; however, in comparison to other scintigraphic modalities, scintigraphy with the antigranulocyte antibody BW 250/183 is superior in excluding infection and has better specificity and accuracy. Therefore, as in the case of hip prostheses, the described methodology appears to be the scintigraphic modality of choice for knee prostheses.     

Antigranulocyte scintigraphy in infected hip prosthesis: the diagnostic importance of delayed 20-24-h imaging and semiquantitative analysis

AIM: To evaluate clinical efficacy of a dual-time acquisition protocol, which included 4 and 20/24-h imaging with antigranulocyte antibody scintigraphy (LeukoScan) combined with semiquantitative analysis in the diagnosis of infection in painful hip prosthesis. METHODS: Sixty-seven consecutive patients with hip prosthesis were enrolled in this research project: 35 females, 32 males, mean age of 56.3 years. All patients had clinical and biochemical suspicious of infection. Each prosthesis had been implanted 3 months to 12 years before enrollment in this study. Twenty-four patients were on antibiotic therapy at the time of scintigraphy. Seven patients had bilateral hip prosthesis, one painful and the other painless: the seven painless prostheses were considered controls. LeukoScan examination was performed both at early (4 h) and delayed (20/24 h) times. The scintigraphic data were assessed both by visual and semiquantitative methods by three experienced nuclear medicine physicians blinded to clinical, laboratory and radiographic results. The uptake was graded visually by a 4-point scale: intense=3, moderate=2, mild=1 and absent=0. The semiquantitative analysis was obtained by a region of interest (ROI) analysis used in the anterior views to measure the ratio between the mean radioactivity in the prosthesis and the background radioactivity in the early and delayed images. An increase in the intensity of uptake of at least one scale-step at visual analysis and 20% at semiquantitative ROI analysis at the dual-time (early vs. delayed) LeukoScan was considered consistent with infection, whereas a stable or decreasing pattern was judged a negative result. Three-phase 99mTc-hydroxymethane diphosphonate bone scan was also performed routinely. Final diagnosis was determined at surgery and/or long-term clinical and imaging follow-up. RESULTS: At visual analysis, sensitivity for both early and delayed imaging was 94%, whereas specificity was 71% for early imaging and 83% for early and delayed imaging approach. At semiquantitative ROI analysis, sensitivity remained 94%, whereas specificity rose slightly to 73% for early imaging and to 90% for early and delayed imaging combined. Of note, four false-positive early scans were diagnosed correctly as negative on delayed imaging showing a decreasing pattern in uptake intensity. Sensitivity and specificity were similar whether patients were on or off antibiotic therapy. CONCLUSION: Our data show that early imaging LeukoScan is highly sensitive in evaluating septic prosthesis, but it is not optimally specific. Although the dual-time LeukoScan is capable of significantly increasing specificity for detecting infection. The semiquantitative ROI analysis further increased the specificity. Concomitant antibiotic treatment did not seem to influence the diagnostic efficacy of LeukoScan scintigraphy in detecting infected hip prosthesis.     

Scintigraphic assessment of the acetabulum after arthroplasty with reference to cup geometry

A unique scintigraphic appearance has been noted in uncomplicated hip prostheses which have the acetabular component inserted after under-reaming or where a cone-shaped cup is inserted. We hypothesized that the pattern of increased uptake around the superior and inferior third of the cup with relatively reduced uptake in the medial third is due to preferential loading of the rim of the cup. A prospective study of ten patients with uncomplicated hip prostheses supports the hypothesis.     

Cemented total hip prosthesis: radiographic and scintigraphic evaluation

Conventional radiographs, technetium-99m bone scans, and gallium-67 scans were reviewed in 44 patients who had undergone cemented total hip joint replacement and were imaged because of suspicion of prosthesis loosening or infection. A complete radiolucent line of 2 mm or wider along the bone-cement interface or metal-cement lucency on conventional radiographs was used as the criterion for prosthetic loosening with or without infection and proved to be 54% sensitive and 96% specific. Scintigraphic criteria for prosthetic loosening were increased focal uptake of the radiopharmaceutical for the femoral component and increased focal or diffuse uptake for the acetabular component. For bone scintigraphy, sensitivity was 73% and specificity was 96%. Combining the results of conventional radiographs and bone scans increased sensitivity to 84% and decreased specificity to 92% for the diagnosis of loosening, infection, or both. The study also showed that Ga-67 scintigraphy has a low sensitivity for the detection of infection.     

99Tcm-nanocolloid imaging in inflammatory bowel disease

We have used 99Tcm-labelled nanocolloid in an attempt to locate areas of inflamed bowel wall or abscesses in five patients with ulcerative colitis and nine with Crohn's disease. The scintigraphic findings were evaluated by comparison with those of recent barium studies and, in three patients, with surgical findings at laparotomy. It proved difficult to localize segments of inflamed bowel accurately with 99Tcm-nanocolloid because of the accumulation of radioactivity in the gut lumen, especially 2 or more hours after injection. However, there was little uptake of the labelled nanocolloid by areas of inflamed gut wall in the period before 2 h. When 99Tcm-nanocolloid scans were compared with 111In-WBC scans in eight patients who had both investigations, 99Tcm-nanocolloid scintigraphy was considerably less sensitive than 111In-WBC scintigraphy. One abscess was located correctly; the other was obscured by nearby bladder and bone marrow radioactivity. We conclude that 99Tcm-nanocolloid scanning is neither sensitive nor reliable enough for assessing the location of inflamed bowel wall or the presence of abscess in patients with inflammatory bowel disease.     

The use of [18 F]fluorodeoxyglucose positron emission tomography to differentiate between synovitis,loosening and infection of hip and knee prostheses

Pain is a common unspecific symptom in orthopaedic prosthetics. The accurate differentiation between synovitis, loosening or infection is often difficult with conventional X-rays, arthrography or bone scintigraphy. Because of the high glucose uptake of inflammatory cells, [18F]fluorodeoxyglucose (18F-FDG) is an appropriate tracer for the evaluation of suspected inflammation or infection. In this preliminary study we describe 18F-FDG PET findings in patients referred for evaluation of painful hip or knee prostheses. We studied 23 patients with 28 prostheses, 14 hip and 14 knee prostheses, who had a complete operative or clinical follow-up. 18F-FDG PET scans were obtained with an ECAT EXACT HR+ PET scanner. High glucose uptake in the bone prostheses interface was considered as positive for infection, an intermediate uptake as suspect for loosening, and uptake only in the synovia was considered as synovitis. The imaging results were compared with operative findings or clinical outcome. PET correctly identified three hip and one knee prostheses as infected, two hip and two knee prostheses as loosening, four hip and nine knee prostheses as synovitis, and two hip and one knee prostheses as unsuspected for loosening or infection. In three patients covered with an expander after explantation of an infected prosthesis PET revealed no further evidence of infection in concordance with the clinical follow-up. PET was false negative for loosening in one case. Our preliminary results suggest that FDG PET could be a useful tool for differentiating between infected and loose orthopaedic prostheses as well as for detecting only inflammatory tissue such as synovitis.     

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.     

Asymptomatic total hip prosthesis: natural history determined using Tc- 99m MDP bone scans

A prospective study was performed with 97 patients who had undergone total hip replacement surgery and who were not experiencing pain or other symptoms or problems. The study was intended to determine the normal postoperative appearance of radionuclide scans of the hip following administration of technetium-99m methylene diphosphonate. Five areas of the prostheses were evaluated. Results showed that 6 months after implantation activity around the lesser trochanter and prosthesis shaft became insignificant. Activity around the acetabulum, greater trochanter, and prosthesis tip stabilized approximately 2 years after surgery; approximately 10% of patients in the study had persistent activity in these areas. Familiarity with this normal progression is fundamental to interpretation of postoperative bone scans in patients with total hip prosthesis.     

Bone scintigraphy in patients with bipartite patella

This study was performed to assess the diagnostic value of bone scintigraphy to differentiate symptomatic bipartite patella from asymptomatic bipartite patella. Thirty-seven bipartite patellae (15 symptomatic and 22 asymptomatic) were evaluated by bone scintigraphy. Bone scintigraphic activity in bipartite patella was classified into the following four groups. Group A: Eleven bipartite patellae (10 symptomatic and 1 asymptomatic) demonstrated physiological and marked uptake at the epiphysio-metaphysial junction of the distal femur in bone scintiscans. Therefore, high scintigraphic uptake in the bipartite patella was difficult to distinguish from such uptake due to overlap. Group B: Five bipartite patellae (4 symptomatic and 1 asymptomatic) demonstrated both physiologically high scintigraphic uptake at the epiphysio-metaphysial junction of the distal femur and high scintigraphic uptake in the bipartite patella. Group C: Seventeen bipartite patellae (1 symptomatic and 16 asymptomatic) demonstrated abnormally high scintigraphic uptake in the bipartite patella. Group D: Four asymptomatic bipartite patellae did not demonstrate an abnormally high scintigraphic uptake. After excluding Group A, the proportion of positive bone scans in bipartite patella was 84.6% (22 of 26 patellae). Similarly, after excluding Group A, the proportion of positive bone scans in symptomatic bipartite patella was 100% (5 of 5 patellae) and in asymptomatic bipartite patella 81.0% (17 of 21 patellae). Statistical analysis using Fisher's exact test showed no significant differences in the proportion of positive bone scans between both groups (P = 0.5457). In conclusion, abnormally high scintigraphic uptake is frequent findings in both symptomatic and asymptomatic bipartite patella, and bone scintigraphy is not useful to differentiate between them. Therefore, surgical treatment should not be considered based only on scintigraphic findings.     

Detection of osteomyelitis at fracture nonunion sites: comparison of two scintigraphic methods

Forty-nine patients with 50 fracture nonunions 4-48 months after injury underwent technetium-99m methylene diphosphonate (99mTc-MDP) scintigraphy on day 1, combined 99mTc-MDP and indium-111 leukocyte (111In-WBC) scintigraphy on day 2, and gallium-67 (67Ga) scintigraphy on day 3. The results were compared to evaluate the relative abilities of these scintigraphic techniques to detect osteomyelitis. Nine patients had clinical evidence of infection at the time of imaging, and 40 patients (41 fractures) did not. Open-biopsy cultures were performed at all fracture sites and were positive at 21 (42%) of the 50 sites. Combined 99mTc-MDP/111In-WBC images were interpreted with the use of two criteria. A positive study by the first criterion required 111In-WBC localization in the region of the nonunion fracture. A positive study by the second criterion required 111In-WBC localization in bone at the fracture site. The first criterion yielded a sensitivity of 84%, specificity of 72%, and accuracy of 74%; the specificity improved to 97% with an accuracy of 88% when the second criterion was used. Ten (25%) of the 40 patients thought not to have osteomyelitis by clinical criteria at the time of imaging had true-positive 99mTc-MDP/111In-WBC studies by biopsy culture results. Gallium-67 studies were interpreted as nondiagnostic if localization of radioisotope at fracture sites was equal to that with 99mTc-MDP, positive if 67Ga localization was greater than that of 99mTc-MDP, and negative if it was less than that of 99mTc-MDP. Twenty-one 67Ga studies were interpreted as nondiagnostic; 11 (52%) of the 21 had culture-positive fracture sites. The accuracy of 67Ga/99mTc-MDP imaging was 39%. Combined 99mTc-MDP/111In-WBC imaging is useful in the detection of osteomyelitis at fracture nonunion sites and improves the specificity of 111In-WBC imaging by differentiating inflammation/infection in adjacent soft tissue from osteomyelitis at the fracture site. Gallium-67 with 99mTc-MDP imaging is not sufficiently reliable in this clinical setting to be useful as an indicator for osteomyelitis.     

99mTc-HMPAO-leukocyte scintigraphy in patients with symptomatic total hip or knee arthroplasty: improved diagnostic accuracy by means of semiquantitative evaluation.

The aim of this study was to evaluate the diagnostic value, in suspected infectious prostheses, of (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) leukocyte scintigraphy interpreted with the addition of a semiquantitative analysis. METHODS: By means of a retrospective review, we included a group of 78 consecutive patients with suspected hip or knee prosthesis infection. We performed 91 (99m)Tc-HMPAO-leukocyte scintigraphies and examined 95 localizations that were suspect. Images were acquired at 3 different time points after the injection of the labeled leukocytes: 50 min (early images), 4 h, and 24 h (late images). The scintigraphic examinations were independently evaluated by 3 observers; qualitative and semiquantitative analyses were performed. The final diagnosis of infection was based on surgical, histologic, and bacteriologic data and follow-up. RESULTS: On qualitative analysis, sensitivity, specificity, and accuracy were 80.4%-87%, 65.3%-71.4%, and 75.8%-77.9%, respectively. On semiquantitative analysis, sensitivity, specificity, and accuracy were 95.6%, 95.8%, and 95.8%, respectively. The analysis of 95% confidential intervals showed statistically significant differences in specificity and accuracy between semiquantitative and qualitative analyses. CONCLUSION: In those patients who underwent (99m)Tc-HMPAO-leukocyte scintigraphy for suspected hip or knee prosthesis infection, the addition of a semiquantitative evaluation to the qualitative analysis of early and late images leads to a significant improvement in both specificity and accuracy.     

Indium-111-leukocyte imaging in acute cholecystitis

Eleven patients with suspected acute cholecystitis underwent sequential 99mTc-iminodiacetic derivative (IDA) and 111In-white blood cell (WBC) imaging to determine if 111In-WBCs accumulate within an acutely inflamed hemorrhagic gallbladder wall and, thus, could be employed as a reasonable alternative to 99mTc-IDA scintigraphy in detecting acute cholecystitis. Seven patients had surgically confirmed acute cholecystitis. Of these cases, five had a true-positive 99mTc-IDA and 111In-WBC, one an indeterminate 111In-WBC and true-positive 99mTc-IDA, and one a true-positive 111In-WBC and false-negative 99mTc-IDA scan. The remaining four patients did not have acute cholecystitis. All visualized their gallbladder within 1 hr after 99mTc-IDA administration and none had 111In-WBC gallbladder wall uptake. Both 111In-WBC and 99mTc-IDA scintigraphy accurately detected acute cholecystitis: hepatobiliary scintigraphy demonstrated a cystic duct obstruction and 111In-WBC imaging detected the inflammatory infiltrate within the gallbladder wall. The sensitivity and specificity of each was 86% and 100%, respectively.     

Radiological evaluation of painful total hip replacement

Ninety-four cases of clinically failed, cemented, total hip prostheses requiring surgery were reviewed to determine the accuracy of preoperative plain radiography, culture of aspirated fluid, arthrography, and bone scanning. When radiopaque cement had been used to embed the prosthesis, plain radiography was highly accurate in detecting a loose femoral component, less so in detecting a loose acetabular component. Culture of aspirated fluid was accurate in diagnosing infection. A positive arthrogram identified loosening with good accuracy; however, a negative arthrogram did not reliably exclude loosening. 99mTc bone scans frequently differentiated loosening from loosening with infection. The suggested sequence of diagnostic tests is plain radiography followed by bone scanning. If the bone scan shows diffuse augmented uptake, culture of aspirated fluid followed by arthrography is indicated.     

99mTc-PEG liposomes for the scintigraphic detection of infection and inflammation: clinical evaluation.

Polyethyleneglycol (PEG) liposomes have been shown to be excellent vehicles for scintigraphic imaging of infection and inflammation in various experimental models. In this article we report on a series of patients with possible infectious and inflammatory disease in whom the performance of 99mTc-PEG liposomes was evaluated. The results of 99mTc-PEG liposome scintigraphy were directly compared with those of 111In-immunoglobulin G (IgG) scintigraphy. METHODS: Thirty-five patients (22 men, 13 women; mean age, 51 y; range, 20-76 y), suspected of having infectious or inflammatory disease, received 740 MBq 99mTc-PEG liposomes intravenously. Imaging was performed at 4 and 24 h after injection. Patients received 75 MBq 111In-IgG 24 h after administration of the liposomes. The scintigraphic results were compared and verified by culture, biopsy, surgery, and follow-up of at least 6 mo. RESULTS: Of the 16 proven infections and inflammations, 15 were detected by 99mTc-PEG liposome scintigraphy: soft-tissue infection (n = 3), septic arthritis (n = 3), autoimmune polyarthritis (n = 2), infected hip prosthesis (n = 1), infected osteosynthesis (n = 1), spondylodiscitis (n = 1), infected aortic prosthesis (n = 1), colitis (n = 1), abdominal abscess (n = 1), and pneumonia (n = 1). 99mTc-PEG liposome and 111In-IgG scintigraphy both missed 1 case of endocarditis. In addition, an 111In-IgG scan of a patient with mild soft-tissue infection was false-negative. Concordantly false-positive scans were recorded from 2 patients, both with uninfected pseudarthrosis and focal signs of sterile inflammation. During liposomal administration, 1 patient experienced flushing and chest tightness, which rapidly disappeared after lowering the infusion rate. No other adverse events were observed. CONCLUSION: This clinical evaluation of 99mTc-PEG liposomes shows that focal infection and inflammation can be adequately imaged with this new agent. The performance of 99mTc-PEG liposomes is at least as effective as that of 111In-IgG. With the simple and safe preparation and the physical and logistic advantages of a 99mTc label, 99mTc-PEG liposomes could be an attractive agent for infection or inflammation imaging.     

Bone-ingrowth hip prostheses in asymptomatic patients: radiographic features

The radiographic changes of 85 bone-ingrowth femoral prostheses in 77 asymptomatic patients were reviewed. The average postoperative follow-up time was 21.8 months. In decreasing order of frequency, the alterations included (a) remodeling of the proximal medial edge of the cut femoral neck (stress shielding) (98%), (b) linear lucency with a thin sclerotic margin at the prosthesis-bone interface (that may increase in width or length with time) (79%), (c) endosteal sclerosis at the prosthesis tip (36%), (d) heterotopic bone (24%), (e) cortical thickening at the tip of the prosthesis (12%), (f) prosthetic subsidence (7%), (g) intraoperative fracture (7%), and (h) periosteal reaction (4%). In this study, radiographic evidence of these findings was not associated with clinical failure. This is in distinction to the findings in cemented prostheses, in which many of these phenomena (especially the development of increasing width of the lucent line adjacent to the cement or prosthesis) have been associated with failure. Long-term investigations of porous-coated prostheses are necessary. Currently, however, an awareness of the radiographic alterations that occur with asymptomatic bone-ingrowth prostheses can prevent their misinterpretation as abnormal.     

False-positive radionuclide arthroscintigraphy with a porous-coated total hip prosthesis.

The evaluation of a painful hip prosthesis for suspected loosening frequently requires a multi-modality approach. Radionuclide arthroscintigraphy is a valuable adjunct to contrast arthrography, demonstrating greater sensitivity than contrast arthrography in detecting loosening of the femoral component of the prosthesis. Despite its reliability in the evaluation of cemented hip prostheses, the value of arthroscintigraphy in patients with uncemented or porous-coated prostheses is undetermined. The case of a false-positive radionuclide arthroscintigram in a patient with an uncemented prosthesis is reported. The literature is briefly examined, and the potential implications regarding interpretation of arthroscintigraphy in patients with porous-coated prostheses are discussed.     

Scintigraphic abnormalities in patients with painful hip replacements treated conservatively.

A retrospective review of the scintigraphic appearances of 98 painful hip replacements was made. 16 patients (16%) underwent revision surgery whereas in the remaining 82 hips (84%), symptoms settled with conservative management. 73 of these (89%) had at least one area of increased activity on delayed diphosphonate scintigraphy with 27% having increased activity in three or more areas around the femoral component. Hips with increased activity at the lesser trochanter and tip were less likely to undergo spontaneous resolution of symptoms. Uncemented prostheses were more likely to have multiple areas of increased activity. Abnormalities in dynamic bone scintigraphy and gallium studies were also seen in patients whose symptoms resolved without surgery. Whereas a normal bone scintigram indicates that loosening or infection is most unlikely, the presence of increased activity does not necessarily indicate a need for revision surgery, even when multiple areas are present. A period of conservative management should be considered before operative intervention is undertaken.     

Quantitative analysis of radiophosphate uptakes in asymptomatic porous-coated hip endoprostheses

A quantitative analysis of the uptake of radiophosphate adjacent to the femoral component of a porous-coated cementless prosthesis was undertaken in asymptomatic patients in order to establish normal temporal changes. The group consisted of 55 patients with 62 arthroplasties of 1.6-49-mo duration. Ratios of the stem, stem tip, greater trochanter, lesser trochanter and calcar, and normal femur to the reference sacroiliac joint were obtained, as well as tip-to-stem, and stem-to-normal femur in unilateral arthroplasties. The ratios remained stable at 12 months and beyond, except for the tip and lesser trochanter. Tip-to-stem and tip-to-sacroiliac joint ratios decreased by 24% and 33%, respectively, between 12 and 49 mo. There was also a decrease in the relative uptakes at the lesser trochanter and calcar in the same time interval. Evidence is given that different designs of prostheses may not have the same normal temporal uptakes of radiophosphate.