Well-established nucleon resonances revisited by double-polarization measurements

The first measurement is reported of the double-polarization observable G in the photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. The new results are compared to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of the long-lasting efforts to understand γp→pπ(0) as the simplest photoproduction reaction, surprisingly large differences between the new data and the latest predictions are observed which are traced to different contributions of the N(1535) resonance with spin parity J(P)=1/2(-) and N(1520) with J(P)=3/2(-). In the third resonance region, where N(1680) with J(P)=5/2(+) production dominates, the new data are reasonably close to the predictions.

[The operative treatment of rhizarthrosis for patients with extreme exposure of the hand by athletic activities--is the trapeziectomy with interposition of an pyrocarbon spacer a option for treatment?]

PURPOSE

The rhizarthrosis is the most common degenerative joint disease of the hand. Incidence is detected around 10 %. For the treatment of rhizarthrosis different conservative and surgical methods are available. As many publications deal with the outcome of different surgical procedures. However there are no experiences in possibility of resuming an extreme exposure of the hand by athletic activities and the relevant timeframe between surgical treatment and the resumption as well as which of the competing surgical procedures you should suggest the patient.

CASE REPORT

A female 46-year-old tennis player went to hospital in January 2005 with rhizarthrosis in stage 3 according to Eaton of the dominant right hand with pain during rest and exertion in the right basal joint. She was treated with trapeziectomy and interposition of a pyrocarbon spacer. Since the last clinical and radiological check in spring 2009, the patient is completely free of complaints and has resumed to play tennis 1 - 2 hours per day at tournament level. The correct position of the pyrocarbon spacer is radiologically verified while the joint space in the carpo-metacarpal joint is constant.

CONCLUSION

The trapeziectomy with interposition of an pyrocarbonspacer is a worthfull alternative compared to other established operative techniques. The demonstrated casuistic proves that this treatment matches both the high and multiaxial stress on the first ray of athletes. Four dislocations in the examined collective and the price of the implant of 930 Euro has to be discussed critically.

Impact on postoperative pain of long-lasting pre-emptive epidural analgesia before total hip replacement: a prospective, randomised, double-blind study

Clinical studies on pre-emptive analgesia have produced inconsistent results. We conducted a clinical study investigating the effect of long-lasting pre-emptive epidural analgesia on consumption of analgesics and acute pain. Forty-two patients scheduled for elective hip replacement for osteo-arthritis were randomly assigned to receive, on the day before operation, either 5 ml.h(-1) ropivacaine 0.2% (study group, n = 21) or 5 ml.h(-1) saline (control group, n = 21). Postoperative analgesia was achieved in both groups by patient-controlled epidural analgesia (PCEA) with ropivacaine 0.2%. The main outcome measure was consumption of local anaesthetics. Additional parameters included visual analogue pain scale (VAS) scores, consumption of rescue analgesics, requests for PCEA boluses, and side-effects. The pre-operative parameters and pain scores were similar in the two groups. Epidural blocks provided sufficient operative analgesia in all patients. Pre-emptive analgesia was continued for 11-20 h and led to significantly decreased pain scores before surgery. The consumption of local anaesthetics was decreased postoperatively in the study group (194 mg vs. 284 mg in the postoperative period). Furthermore, bolus requests occurred more frequently in the control group. VAS scores did not differ significantly between groups. Long-lasting "pre-emptive" epidural analgesia decreases postoperative pain with improved pain control.

Stufendiagnostik bei postinfektiöser Hüft- und Knie-TEP-Implantation: Aussagekraft von Laborparametern und Antigranulozytenszintigraphie

AIM

In the case of two-stage infect revision arthroplasties of hip and knee joint, of primary resection arthroplasties and before implantation of arthroplasties after septic arthritis the accuracy of preoperative laboratory parameters and antigranulocyte scintigraphy was analysed. Furthermore, we stained the intraoperatively taken joint synovial samples with hematoxylin-eosin and also with antibodies against human neutrophil elastase in order to investigate if immunohistological examination provides further or different information.

METHOD

In 24 patients with intraoperative verification of infection we calculated sensitivity, specificity, positive and negative predictive values for laboratory tests, antigranulocyte scintigraphy and the most suitable combination of both. The joint synovial samples stained with antibodies against human neutrophil elastase were compared to those stained with hematoxylin-eosin according to the criteria of Mirra.

RESULTS

We observed the best results for the combination of C-reactive protein and antigranulocyte scintigraphy with a sensitivity of 1, a specificity of 0.92, a positive predictive value of 0.75 and a negative predictive value of 1. No additional or different information was observed by the immunohistological stained samples.

CONCLUSION

Stage diagnostic using C-reactive protein and antigranulocyte scintigraphy provides accurate information to assess the status of infection before hip and knee replacement after infect revision. Additional immunohistological staining besides the routinely taken hematoxylin-eosin staining of joint synovial samples is not recommended.

Die Schenkelhalsfraktur beim alten Menschen ? Bipolare Hemiendoprothese vs. Totalendoprothese

INTRODUCTION

In this study surgical risk and functional outcome of bipolar hemiarthroplasty and total hip replacement in elderly patients with femoral neck fractures were compared.

METHODS

In a prospective study 54 patients with femoral neck fractures (median age: 80.5 years) were treated by implanting a total hip replacement (group I). Group II comprised 52 patients with 55 femoral neck fractures (median age: 81 years) who underwent bipolar hemiarthroplsty. Pre- and postoperative mobility and social history, perioperative parameters such as duration of surgery, blood loss, and number of transfused blood units as well as postoperative complications and mortality were compared. Function was ascertained by a scoring system.

RESULTS

Duration of surgery, blood loss, and numbers of transfused blood units were significantly lower in group II, and mortality rate was lower. Postoperative mobility and medium-term functional score were comparable, whereas in the longer-term follow-up after 8 years group I had a significantly better functional score.

CONCLUSION

In elderly patients with femoral neck fracture and high comorbidity, we recommend the implantation of hemiarthroplasty and in healthy, active patients with longer life expectancy the total hip replacement.

[Osteochondritis dissecans - an easy classification in MRI]

AIM

For the diagnosis of osteochondritis dissecans (OD) MRI is used besides X-ray. However, there is no consensus about the necessity of MRI or the interpretation of MRI. The aim of this prospective study was to find a diagnostic concept for OD which is simple and practicale for daily routine.

METHOD

In 90 patients with OD of the knee or ankle MRI (T1- and T2-w SE) was carried out before arthroscopy. According to the interface between the osteochondral fragment and the parent bone, MRI was classified in 2 stages ("stable" or "unstable") and compared with the arthroscopic findings.

RESULTS

With the 2-stage classification of MRI, a prediction of the stability of the osteochondral fragment was possible in 92 %. Out of the 90 patients 7 (8 %) differed regarding preoperative stability in MRI compared to stability in arthroscopy. Incorrect diagnosis in MRI was only found among the patients with unstable fragments.

CONCLUSION

The chosen 2-stage classification in MRI is well suitable for the planning of stage-related therapy.

Regional hemostatic status and blood requirements after total knee arthroplasty with and without tranexamic acid or aprotinin

Antifibrinolytics seem to reduce postoperative blood loss after total knee arthroplasty. Few studies have shown the impact of these drugs on the mechanisms of coagulation. The purpose of this study was to examine coagulation/fibrinolysis variables as well as blood loss after total knee arthroplasty with and without antifibrinolytics in the operated limb on a regional level. Thirty-six patients were randomized into one of three groups to receive aprotinin, tranexamic acid, or no medication. We took blood samples of the femoral vein before deflating the tourniquet and after 5, 10, 30, 60, 120 min and on the first postoperative day. The implantation of a knee prosthesis in artificial ischemia caused a significant activation of coagulation and fibrinolysis in the regional circulation. Tranexamic acid and aprotinin did not cause a significant modulation of fibrinolysis variables or a significant reduction of postoperative bleeding and transfusion requirements. One of the differences in comparison to other studies was the decreased total blood loss. The use of bone cement as well as surgical hemostasis before wound closure may be regarded as reasons for this. Therefore, primarily these methods should be used because there is no increased risk of adverse drug effects.

IMPLICATIONS

After total knee arthroplasty total blood loss may be kept in a low range if methods such as cemented knee prosthesis and surgical hemostasis are used. In this case aprotinin and tranexamic acid did not cause a significant modulation of fibrinolysis variables or a significant reduction of postoperative bleeding.

[The value of magnetic resonance imaging in the clinical course of osteochondrosis dissecans in the knee and ankle joints]

PURPOSE

Definition of the prognostic value of clinical and morphological findings in the mid-term follow-up of OCD of the femoral condyle and talus. Demonstration of the consolidation of OCD on MRI depending on different therapies.

MATERIALS AND METHODS

76 patients were examined before and at an average of 30 months after conservative or surgical therapy using T1 and T2 weighted SE and 3D-FISP sequences and contrast enhanced studies. Six clinical (age, gender, site, duration and severity of symptoms, therapy) and six morphological (size, signal intensity, fragmentation, contrast enhancement, condition of cartilage, staging) data were registered on first MRI and correlated with the degree of consolidation of OCD (partial and complete remission, no change and progression) on control MRI.

RESULTS

Patients under 17 years showed partial or complete remissions in 73%, those of 17 years or older in 33%. Conservatively treated patients had a higher remission rate (54%) than those treated with different surgical techniques (drilling 50%, refixation 43%, abrasio 38%). Small OCDs had a higher remission rate than large lesions (63% vs. 33%). OCDs covered with intact cartilage healed better than lesions with chondral defects (61% vs. 26%). Contrast enhancing fragments had a better prognosis than non-enhancing lesions (100% vs. 40%).

CONCLUSIONS

Prognosis of OCD can be better estimated when size of OCD, condition of cartilage and enhancement of contrast agent is graduated with MRI and patient age is registered. The consequences for therapy planning are great.

[The diagnostic accuracy and therapeutic relevance of CT arthrography and MR arthrography of the shoulder]

PURPOSE

In glenohumeral instability, CT arthrography and MR arthrography of the shoulder joint were compared to assess accuracy in diagnosis of labral lesions and other internal derangements of the joint, and to evaluate relevance of both imaging methods for therapy.

METHODS

38 patients with symptoms of shoulder instability were examined clinically, arthrographically with CT and MRI, and arthroscopically. Arthrography with CT and MRI was performed in a double-contrast technique after single puncture and simultaneous injection of the contrast agents for both imaging methods. Type and extent of lesions on arthrographic imaging were criteria for planning therapy to a conservative, sole arthroscopic, or open surgical approach.

RESULTS

Sensitivity in diagnosis of labral lesion (26 defects) was 85% in CT, 88% in MRI and 100% if both methods were used. Full-thickness tears of the rotator cuff were visualised in CT in 73%, and in MRI in 100%. Diagnostic accuracy increased from partial to complete to total defects. An open surgical approach was correctly predicted on MRI in 90% and on CT in 71%. A sole arthroscopic therapy was correctly foreseen on both arthrographic techniques in only 38% due to difficulties to assess glenohumeral ligaments.

CONCLUSIONS

CT arthrography and MR arthrography were excellent for diagnosing labral lesions. MRI is superior to CT in the imaging of all joint structures. Surgical approach can be accurately predicted with both imaging methods but special surgical techniques cannot be effectively planned to replace diagnostic arthroscopy in all cases.

[Comparison of different MRT techniques in the diagnosis of degenerative cartilage diseases. In vitro study of 50 joint specimens of the knee at T1.5]

PURPOSE

An experimental study was performed on joint specimens of the knee to assess the advantages and disadvantages of 14 generally available sequences in cartilage imaging.

METHODS

Each of the 50 surgically exposed cadaveric joints of the knee was examined by the following sequences: T1, proton- and T2 weighted spin echo(SE) sequences, proton- and T2 weighted Turbo-SE, T1 weighted SE with fat suppression, MTC combined with T1-weighted SE and T2 weighted FLASH-2 D, STIR, FISP-3 D, FLASH-3 D (with fat suppression), and MR arthrography. We assessed the image quality by a scale, signal to noise-ratio of cartilage and joint fluid, and the accuracy in detection of cartilage lesions. Pathology and arthroscopy were reference methods to MRI, and demonstrated grade 1-4 lesions on 186 of 300 joint facettes.

RESULTS

Advanced stages of cartilage lesions (65 grade 3 and 4 lesions) were detected by standard SE sequences in 67-94%. Application of volume techniques (FISP-3 D, FLASH-3 D), high definition matrix (512 pixel), MTC with FLASH-2 D and MR-arthrography improved the sensitivity up to 82-100%. Superficial lesions (65 grade 2 lesions) were demonstrated in 3-38%, and on MR arthrography in 45%. Structural changes (56 Grade 1 lesions) were recorded on MR) in only 10%.

CONCLUSIONS

With regard to standard SE sequences, the detectability of cartilage lesions can be improved by techniques that use 512 matrices, selective cartilage imaging, and volume acquisition.

[Value of arthro-CT in decision for arthroscopic or open stabilization in ventral shoulder instability]

A prospective study was performed on 30 patients with anterior instability of the shoulder to assess the diagnostic value of preoperative arthro-CT. One special diagnostic problem was the definition of diagnostic criteria for arthroscopic or open surgery. Arthro-CT of the shoulder was performed with a double-contrast technique. Visualization of labral tears, bony lesions, glenohumeral ligaments and disruption of the rotator cuff was registered. Findings of arthro-CT were verified by diagnostic arthroscopy. Therapy consisted of either arthroscopic or open surgery depending on the lesion pattern found in diagnostic arthroscopy. The most common cause of anterior instability (90% of cases) was damage of the ventro-caudal labral complex, which was diagnosed by arthro-CT with a sensitivity of 93% and a positive predictive value of 93%. Specificity and negative predictive value were reduced to 33%; the overall accuracy was 87%. In all, 16 patients were successfully treated using arthroscopic stabilization because whereas 14 patients required open surgery because diagnostic arthroscopy contraindicated an arthroscopic approach. The preoperative arthro-CT failed to define all criteria mandatory for the decision for arthroscopic or open surgery because pathoanatomy of the joint was not sufficiently demonstrated with the current technique of arthro-CT.

[Clinical value of conventional radiology and MRI in assessing osteochondrosis dissecans stability]

A prospective study was performed on 72 patients with osteochondritis dissecans (OD) of the knee and ankle to compare plane radiography, MRI and arthroscopy before therapeutic procedures. Special interest was placed on the assessment of fragment stability with radiological methods for staging related therapy. OD was localized in 46 cases on the femoral condyle and in 26 cases on the talus. Radiological methods were performed simultaneously and shortly before definite arthroscopical therapy. Using conventional radiography, OD of the condyles was staged according to the classification of Rodegerdts and Gleissner and OD of the talus suggested by Berndt and Harty. MRI staging was performed by morphology of the interface of the OD. Arthroscopical staging based on the classification of Guhl. There was an excellent correlation between the stages in MRI and arthroscopy, showing correct prediction of stable and unstable fragments in 92%. In contrast, fragment stability could not be efficiently assessed by conventional radiology because fragments could be stably fixed in cases of bony separation. MRI is indicated before performance of staging-related therapy of OD to select patients with stable fragments for conservative therapy and those with unstable OD for surgical therapy.

[MRI in hemarthrosis of the knee joint: assessment of cause of bleeding, injury pattern and therapy]

PURPOSE

Patients with hemarthrosis of the knee were examined by MRI and arthroscopy to identify the bleeding source and to determine surgical or conservative therapy.

METHODS

A prospective study was performed on 120 patients who underwent MRI and arthroscopy. Joint lesions and bleeding sources were documented separately on a standardised form.

RESULTS

Arthroscopy demonstrated a ruptured anterior cruciate ligament in 86%, meniscal tears in 55%, disruption of collateral ligaments in 17%, osteochondral lesions in 5% and tears of capsule or plicae in 13%. Disruption of cruciate ligaments caused haemorrhage in all but three cases. In contrast, only meniscal tears located very adjacent to the meniscal basement had bled. Those types of osteochondral lesions caused haemorrhage characterised on MRI by destruction of the subchondral plate and overlying cartilage. Severe lesions of the knee were diagnosed by MRI in 71% to 100%, slight lesions in 13% to 40% of the cases. Single, combined and bland lesions were accurately diagnosed in MRI which permitted a correct prediction of surgical and conservative therapy in 96% and 80%.

CONCLUSIONS

Morphological criteria in MRI permit identification of bleeding sources in hemarthrosis of the knee. Different lesion patterns can be separated for the planing of therapy.

[Traumatic hemarthrosis of the knee joint--clinical significance of nuclear magnetic resonance tomography]

A prospective study was performed on 94 patients with hemarthrosis of the knee to assess the value of MR imaging (MRI) in detection of bleeding sources and selection of therapy modalities. Patients were examined clinically within a week after knee trauma; the investigations performed included puncture of the joint to confirm hemarthrosis, a conventional X-ray to exclude fractures, MRI and arthroscopy. MRI was performed for diagnosis of acute lesions, definition of bleeding sources by morphological criteria, and allocation of patients to conservative or surgical therapy. Arthroscopy was performed to control MRI, to visualize bleeding sources, and to maintain therapy if necessary. The 94 patients were found on arthroscopy to have a total of 123 bleeding sources, which were correctly defined by MRI in each of 107 cases as an acute lesion communicating with the joint space; 16 bleeding sources were not found and there were 10 false-positive reports. In keeping with our treatment strategies, arthroscopy disclosed lesions requiring surgical therapy in 77 of 94 patients (82%) and lesions that would be adequately treated by conservative therapy in 17 of 94 patients (18%). MRI predicted surgical or conservative therapy correctly before arthroscopy in 83 of 94 patients (88%). In conclusion, MRI has a high predictive value in definition of acute lesions that will lead to hemarthrosis of the knee. This noninvasive method allows screening out of the relatively small portion of patients without severe lesions, who then do not have to be subjected to further invasive therapy.

[The staging of osteochondritis dissecans in the knee and ankle joints with MR tomography. A comparison with conventional radiology and arthroscopy]

PURPOSE

A prospective study was performed on 50 patients suffering from osteochondritis dissecans of the knee and ankle to define criteria for stability and fixation of osteochondral lesions.

METHODS

Morphological parameters in MRI (size, fragmentation, cartilage, interface) and conventional radiology (separation, fragmentation) were registered and compared with arthroscopic staging. MRI staging based on different types of interfaces was demonstrated on T1- and T2-weighted images.

RESULTS

MRI could correctly predict a Grade 1 lesion in 50%, a Grade 2 lesion in 90%, a Grade 3 lesion in 0%, and a Grade 4 lesion in 79%. Stable lesions were differentiated from unstable lesions in 90%. Radiographic findings corresponded with arthroscopic staging in only 56% of the cases because fibrotic connection may guarantee stability in cases of bony separation.

CONCLUSION

MRI should be performed before therapy to select those patients who do not need surgical therapy or arthroscopy.