So Kubota

Comparison of 18F-fluoride positron emission tomography and magnetic resonance imaging in evaluating early-stage osteoarthritis of the hip.

ObjectiveThe imaging diagnosis of osteoarthritis (OA) of the hip, especially in its early stages, is a technically challenging but essential aspect of our increased understanding of the pathophysiology of this disorder. We recently applied 18F-fluoride PET for the detection of abnormal bone turnover in early-stage OA. In our current study, we have compared the diagnostic and analytical capabilities of 18F-fluoride PET and MRI modalities in a hip OA patient series. Patients and methodsA total of 85 hip joints, including hips at various stages of OA as well as painful, dysplastic, and normal contralateral hips, were analyzed. The average age of our study patients was 50 (range 24–75) years. The Kellgren and Lawrence (K/L) grade was used for radiographic evaluations. Hip pain was graded on the basis of pain severity. 18F-Fluoride PET and MRI data obtained during the same period (within 3 months) were compared for all joints in the study. ResultsWe identified PET positivity (i.e. SUVmax>6.5) in 47 joints, whereas MRI-positive findings were evident in 25 joints. Most (96%) of the MRI-positive joints were also PET positive. The percentage of MRI-positive joints and PET uptake-positive joints was 6 and 18% in K/L grade 0, 16 and 48% in K/L grade 1, 27 and 65% in K/L grade 2, 73 and 87% in K/L grade 3, and 100 and 100% in K/L grade 4, respectively. Among the 23 MRI-negative but PET-positive joints, 21 joints had a K/L grade below 2, and 12 joints showed greater than moderate hip pain. Conclusion18F-Fluoride PET can detect bone abnormalities earlier than MRI in OA of the hip. This probably reflects accelerated bone remodeling due to high stress and may be followed by the appearance of bone marrow edema on MRI.

Teriparatide Versus Alendronate for the Preservation of Bone Mineral Density After Total Hip Arthroplasty – A randomized Controlled Trial

In this study, the effect of teriparatide for the prevention of bone mineral density (BMD) loss after THA was compared with alendronate in a randomized controlled trial. Forty-eight patients were assigned to three groups, namely, the teriparatide, alendronate, and no medication groups. Dual-energy x-ray absorptiometry (DEXA) was performed at 1 week post-surgery as a baseline reference, followed by subsequent measurements at 12, 24, and 48 weeks postoperatively. For periprosthetic BMD loss, a significant effect of teriparatide was demonstrated, though its effect was similar to alendronate. On the other hand, higher lumbar BMD was observed in the teriparatide group than in the alendronate group at 48 weeks post-surgery. Teriparatide administration may be one reasonable option for osteoporotic patient to preserve the periprosthetic BMD after THA.

Influence of Pelvic Tilt on Polyethylene Wear after Total Hip Arthroplasty

We aimed to evaluate the effects of pelvic tilt on polyethylene wear after total hip arthroplasty (THA). A total of 105 joints treated with primary THA were included; conventional polyethylene (CPE) liners were used in 43 hips and highly cross-linked polyethylene (HXLPE) liners were used in the remaining 62 hips. The pelvis was tilted 6° posteriorly in the standing position as compared to the supine position, which resulted in significant increases of 1.7° and 2.8° in cup inclination in the CPE and HXLPE groups, respectively. Moreover, the change in pelvic tilt resulted in significant increases of 3.6° and 4.9° in cup anteversion in the CPE and HXLPE groups, respectively. For the CPE group, multiple regression analysis showed a significant association between the angle of pelvic tilt (PTA) and cup inclination and the polyethylene wear ratio. The adjusted R 2 of the regression model was larger for measures obtained in the standing position as compared to the supine position. For the HXLPE group, there was no significant relationship between radiographic parameters and polyethylene wear. Close observation of polyethylene wear is recommended for patients with severe posterior pelvic tilt who have undergone THA with conventional polyethylene.

Effects of hip joint center location and femoral offset on abductor muscle strength after total hip arthroplasty

Abstract Objectives. The purposes of this study were 1) to examine the changes in the hip joint center (HJC) position and the femoral offset (FO) after total hip arthroplasty (THA) and 2) to investigate the effects of the HJC and FO on isometric abductor muscle strength. Methods. We evaluated 51 patients who underwent unilateral primary THA. The FO, and horizontal and vertical distances from the HJC to the tip of the teardrop were measured and isometric hip abductor muscle strength was measured. Results. The HJC of the affected side moved medially postoperatively compared with that of the unaffected side (p < 0.05), and the FO was reconstructed similarly to the unaffected side. There were significant negative correlations between the changes in the horizontal distance from the HJC and FO to the tip of the teardrop. An increase in the FO and infero-medial cup position optimized hip abductor muscle strength. Conclusion. The HJC was reconstructed medially and superiorly, and the change in the FO after THA was influenced by the change in the horizontal distance of the HJC. Multiple regression analysis revealed that the medial and inferior HJC and increase in the FO constitute an effective procedure for restoring abductor strength.

Computer-Assisted Rotational Acetabular Osteotomy for Patients with Acetabular Dysplasia

Rotational acetabular osteotomy (RAO) is a well-established surgical procedure for patients with acetabular dysplasia, and excellent long-term results have been reported. However, RAO is technically demanding and precise execution of this procedure requires experience with this surgery. The usefulness of computer navigation in RAO includes its ability to perform three-dimensional (3D) preoperative planning, enable safe osteotomy even with a poor visual field, reduce exposure to radiation from intraoperative fluoroscopy, and display the tip position of the chisel in real time, which is educationally useful as it allows staff other than the operator to follow the progress of the surgery. In our results comparing 23 hips that underwent RAO with navigation and 23 hips operated on without navigation, no significant difference in radiological assessment was observed. However, no perioperative complications were observed in the navigation group whereas one case of transient femoral nerve palsy was observed in non-navigation group. A more accurate and safer RAO can be performed using 3D preoperative planning and intraoperative assistance with a computed tomography-based navigation system.

Difference in Postoperative Periprosthetic Bone Mineral Density Changes Between 3 Major Designs of Uncemented Stems: A 3-Year Follow-Up Study.

BACKGROUND Although few studies have examined the direct effect of stress shielding on clinical outcomes, periprosthetic bone loss due to stress shielding is still an issue of concern, especially when physicians perform uncemented total hip arthroplasty (THA) in younger patients. Differences in femoral stem design may affect the degree of postoperative stress shielding. Therefore, the characteristics of the behavior for stress shielding of each type of femoral stem should be determined. This study compares differences in bone mineral density (BMD) change in the femur after primary THA between 3 major types of uncemented stems. METHODS Among a total of 89 hips, 26 hips received THA with a fit-and-fill type stem (VerSys Fiber Metal MidCoat; Zimmer, Inc, Warsaw, IN), 32 hips received a tapered rectangular Zweymüller-type stem (SL-Plus; Smith & Nephew Inc, Memphis, TN), and 31 received a tapered wedge-type stem (Accolade TMZF; Stryker Orthopaedics, Mahwah, NJ). BMD measurements were performed with a HOLOGIC Discovery device (Hologic Inc, Waltham, MA). RESULTS BMD in the medial-proximal femur was maintained for 3 years after THA in the group with the tapered wedge-type stem. BMD in the lateral-proximal femur was maintained for 3 years after THA in the group with the Zweymüller-type stem. There were no significant differences in the Harris Hip Score among the 3 stem groups preoperatively and 1, 2, and 3 years after surgery. CONCLUSION There are clear differences in postoperative BMD loss of the proximal femur among these 3 commonly used uncemented stems.

Prediction of femoral head collapse in osteonecrosis using 18F-fluoride positron emission tomography.

ObjectiveWe investigated the usefulness of 18F-fluoride PET as a predictor of femoral head collapse in patients with osteonecrosis (ON) before radiographic changes occur. Patients and methodsSixty-six hips of 42 patients diagnosed with ON of the femoral head were included in this study. We evaluated the relationship between the maximum standardized uptake value (SUVmax) in 18F-fluoride PET and the Ficat classification. We evaluated the relationship between SUVmax and the presence of femoral head collapse on plain radiography at 12 months after 18F-fluoride PET in 23 hips of 18 patients with Ficat classification stage 1 or 2. A receiver operating characteristic analysis was carried out to calculate the cut-off SUVmax for the prediction of femoral head collapse. We analyzed the relationship between SUVmax and femoral head collapse on plain radiography in the 23 hips using a logistic regression model. ResultsSUVmax increased according to the progression of the Ficat classification stage. The mean SUVmax was 12.3±5.9 in the collapse group and 4.9±1.3 in the noncollapse group (P<0.01). The cut-off SUVmax of 6.45 (sensitivity: 0.80, specificity: 0.92) was used for the prediction of femoral head collapse. In the univariate analysis, SUVmax, type classification, and ring sign were related significantly to femoral head collapse. ConclusionWe showed that the quantitative assessment of SUVmax in 18F-fluoride PET was useful to predict femoral head collapse in ON. 18F-Fluoride PET might reflect accelerated bone metabolism because of microcollapse of the femoral head, which is undetectable on plain radiography.

Use of 18F-fluoride positron emission tomography as a predictor of the hip osteoarthritis progression

Objective. The prediction of hip osteoarthritis (OA) progression is still a difficult issue. We have adopted 18F-fluoride positron emission tomography (PET) for the evaluation of hip osteoarthritis, and investigated the prediction utility of 18F-fluoride PET for both pain worsening and OA progression using a logistic regression model. Materials and methods. A total of 57 hip joints were analyzed for progression risk factors for pain worsening and minimum joint space (MJS) narrowing by logistic regression analysis. Sex, age, BMI, existence of pain, the PET maximum standardized uptake value (SUVmax), Kellgren and Lawrence grade, MJS, and follow-up period were used as explanatory variables. Receiver operating characteristic analysis was performed to calculate the cutoff value of the SUVmax. Results. Multivariate logistic regression analysis revealed significant differences only in the SUVmax values for pain worsening and MJS narrowing. The odds ratio of the SUVmax for pain worsening was 1.89, and for MJS narrowing it was 11.02. The SUVmax cutoff value was 7.2 (sensitivity: 1.00, specificity: 0.84) for pain worsening and 6.4 (sensitivity: 0.92, specificity: 0.83) for MJS narrowing. Conclusions. Our results indicate that the PET SUVmax is a best predictor of pain worsening and MJS narrowing. This imaging modality has a great potential for the prediction of OA progression.

A new multiplex real-time polymerase chain reaction assay for the diagnosis of periprosthetic joint infection

Abstract Objectives: A new multiplex real-time polymerase chain reaction (PCR) assay was developed to detect methicillin-resistant Staphylococcus (MRS) and to distinguish between gram-positive and gram-negative bacteria. In this study, we validated the sensitivity and specificity of this assay with periprosthetic joint infections (PJIs) and evaluated the utility of PCR for culture-negative PJI. Methods: Forty-five samples from 23 infectious PJI cases and 106 samples from 64 non-infectious control cases were analyzed by real-time PCR using a LightCycler Nano® system. Twenty-eight clinical samples, comprising bacteria of known species isolated consecutively in the microbiological laboratory of our hospital, were used to determine the spectrum of bacterial species that could be detected using the new multiplex primers and probes. Results: The sensitivity and specificity of the MRS- and universal-PCR assays were 92% and 99%, and 91% and 88%, respectively. Twenty-eight species of clinically isolated bacteria were detected using this method and the concordance rate for the identification of gram-positive or gram-negative organisms was 96%. Eight samples were identified as PCR-positive despite a culture-negative result. Conclusion: This novel multiplex real-time PCR system has acceptable sensitivity and specificity and several advantages; therefore, it has potential use for the diagnosis of PJIs, particularly in culture-negative cases.

Evaluation of local bone turnover in painful hip by 18F-fluoride positron emission tomography.

ObjectiveThe diagnosis of painful hip without remarkable radiographic findings is still challenging. In recent years, femoroacetabular impingement (FAI) has been recognized as an important cause of painful hip. The hypothesis of this study was that local bone turnover may be accelerated in painful hip, especially in FAI lesions. To test this, patients with unilateral symptomatic hip underwent 18F-fluoride PET, which directly correlates with osteoblast activity and therefore bone turnover. Patients and methodsIn total, 27 patients with unilateral symptomatic painful hip were enrolled. The diagnosis included 15 cam-type FAI cases, six labral tear cases, and six early-stage osteoarthritis cases. The region of interest for cam and pincer lesions was identified and the maximum standardized uptake value (SUVmax) in these regions and the contralateral asymptomatic regions were measured by 18F-fluoride PET. The SUVmax ratio was defined as symptomatic side SUVmax/asymptomatic side SUVmax. The &agr; angle and center-edge angle were measured by plain radiograph. ResultsThe SUVmax of both cam and pincer lesions were significantly higher than the SUVmax of the contralateral regions (P<0.0001). The cam SUVmax ratio correlated positively with the &agr; angle (r=0.5, P=0.007). Patients with an &agr; angle of more than or equal to 60° had a significantly higher cam SUVmax ratio than the less than 60° group (P=0.017). ConclusionThis study showed the accelerated local bone turnover in painful hip, partly in FAI cases. Accelerated bone turnover may play a significant role in FAI pathophysiology; therefore, its recognition by imaging modality may contribute toward a more sensitive diagnosis in painful hip.