Analysis of 18F-FDG uptake patterns in PET for diagnosis of septic and aseptic loosening after total hip arthroplasty

Aim: Identification of typical patterns for fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) to detect aseptic loosening of hip prosthesis (ace-tabular and/or femoral component) and prosthetic infection. Methods: 18 patients with painful hip prosthesis underwent PET using a dedicated full ring scanner after application of 200-300 MBq FDG. The interface between bone and surrounding soft tissue or bone as displayed on coronal slices was divided into 12 segments in accordance with the classifications of Delee and Gruen. FDG uptake in each of the segments was scored (0-3) by two independent observers. Intraoperative findings were regarded as the gold standard. Results: After surgical revision 14 acetabular components and 9 femoral components were found to be loose and prosthetic infection was present in 7 prostheses. Loosening of the acetabular component was correlated to enhanced uptake in the middle of the acetabular interface, while loosening of the femoral component was correlated to enhanced uptake in the proximal and middle segment of the lateral femoral interface and the proximal segment of the medial femoral interface. A similar pattern was found in prosthetic infection with high uptake along the middle portion of the lateral fe-moral interface. In 6 of 7 infected prostheses loosening of the acetabular and of the femoral component was present. Taking the typical uptake patterns as criteria for loosening and grade 3 uptake as an additional criterion for septic loosening the accuracy of PET imaging in the detection of loosening of the acetabular or the femoral component and of prosthetic infection was 72, 78 and 89%, respectively. Conclusion: This pilot study presents FDG-PET as a promising diagnostic tool for patients with painful hip prostheses. Its clinical value should be evaluated in a larger patient population.

[Perioperative management in outpatient arthroscopy of the knee joint]

AIM

Nowadays, complex arthroscopic procedures of the knee joint, such as ACL reconstruction, are routinely carried out on an outpatient basis. The reduced time spent with the patient places high demands on the surgeon with regard to the management of such cases. The aim of this study was to evaluate the current standards of perioperative management following outpatient arthroscopic surgery of the knee in Germany.

METHODS

A questionnaire consisting of 18 questions was sent to 215 members of the German Association of Outpatient Arthroscopy (BVASK e. V.), dealing with the following topics: antibiotic prophylaxis, DVT prophylaxis, use of a tourniquet and suction drain, physical therapy, physiotherapy, analgesia, anaesthesia and emergency management. More than 51% of the forms were returned and considered suitable for statistical analysis.

RESULTS

A total of 62% of the surgeons reported the use of an antibiotic prophylaxis (i. v. single shot) in every arthroscopic case, while 19% administer antibiotics only occasionally, especially in ACL reconstruction. Postoperative antibiotic treatment was reserved for special situations, such as prior joint infection. Prophylaxis of DVT by means of low molecular weight heparin was carried out in 96% of the cases. 51% prescribed anticoagulant agents for 1 week, 39% for the duration of reduced weight bearing. Half of the surgeons used a tourniquet cuff, 22% exsanguinate the limb prior to cuff inflation. A suction drainage was applied by 36% of the surgeons regularly and by 45% occasionally. The drain is left for one day by 79% of the surgeons, while 11% reported a shortened use of only several hours. With regard to analgesia, 66% of all surgeons apply some kind of local anaesthetic into the knee joint post surgery. Systemic preoperative analgesics or anti-inflammatory agents are given regularly in 56 % of the cases. A total of 92% of the procedures are carried out under general anaesthesia. In 36% of the cases, some kind of additional regional peripheral anaesthesia is used. With regard to postoperative care, cryotherapy is considered standard (97%) and 64% of the surgeons recommend physiotherapy. Nearly all surgeons (97%) offer the patients the opportunity to reach them personally via mobile phone during the first night following arthroscopic surgery.

CONCLUSIONS

DVT prophylaxis with LMWH, general anaesthesia, postoperative cryotherapy and personal availability by phone can be considered part of the standard perioperative management following outpatient knee arthroscopy in Germany. However, a wide variety of treatment options can be found regarding topics such as analgesia, antibiotic prophylaxis, tourniquet, knee drainage and physiotherapy.

Trackerless ultrasound-integrated bone cement detection using a modular minirobot in revision total hip replacement

Medical robots are superior to freehand manipulation if an accurate, precise, and time-efficient implementation of a preplanned intervention is required. In the first part of this contribution a new modular minirobot for automatic ultrasound-based bone cement detection followed by subsequent cement milling in revision total hip replacement is presented. A minirobot integrated ultrasound module eliminates the need for external position tracking (e.g. by an optical system) as well as patient registration since the scanned contours can be directly provided within the robot's coordinate system. Further, the modular minirobot concept allows kinematics, workspace, and mechanical parameters to be easily adapted to the requirements of related or even new surgical applications. In the experimental part, the impact of ultrasound module integration on the implementation of optimized scanning strategies is investigated and evaluated in a laboratory set-up. As wave mode conversion and refraction artefacts due to angular sound incidence influence the detection accuracy, the transducer alignment can be optimized with respect to the number of degrees of freedom (DOFs) provided by the minirobot. A model-based scanning approach using two degrees of freedom (2DOFs), three degrees of freedom (3DOFs), and four degrees of freedom (4DOFs) respectively is presented. For automated scanning path calculation, a 2DOF distal-proximal prescan has been performed to estimate the principal components of the cement cavity's geometry using either a model-based or a statistical approach. In a cadaver study, the model-based approach consistently outperformed the statistical approach. The 3DOFs and 4DOFs scanning strategies yielded a significantly higher scanning accuracy if compared with the 2DOFs approach whereas the 3DOFs approach represents a trade-off between system complexity and detection accuracy.

[Periprosthetic bone cement allocation at the femoral durom hip prosthesis. a pilot study: artificial bone models versus ex-vivo femura]

INTRODUCTION

Despite controversial discussions, hip resurfacing at the moment seems to be the most bone-sparing surgical procedure of the femoral bone when implanting hip endoprostheses. Main risks are septic and aseptic loosening and necroses of the coxal end of the femoral bone mainly influenced by the periprosthetic allocation of bone cement. Because of a lack of radiation transparency of the hip resurfacing implant, this cement allocation cannot be sufficiently evaluated by common radiological procedures. A pilot study was conducted to describe and validate the macromechanical interdigitation of bone cement with spongy bone of anatomic specimens compared to artificial bone models and to evaluate whether artificial bones may be used for further interdigitation studies of different implantation techniques.

METHODS

Plastic models of polyoxymethylene (POM) according to the inside geometry of the Metasul Durom hip prosthesis were implanted on ex vivo femora (n = 14) versus artificial bone models (n = 24) (Sawbones) of three different spongy densities (0.16; 0.20; 0.32 g/cm(3)) (each n = 8) in a clinically standardised surgical procedure and reproduced by highly resolving computed tomography. Afterwards a computer-based analysis of the cement allocation was accomplished.

RESULTS

It could be shown that the Sawbones of the lower spongy densities (0.16 and 0.20 g/cm(3)) were similar to the ex vivo femora regarding the bone penetration of cement. No significant differences could be shown regarding interdigitation. According to our data, both groups of Sawbones may be used for further studies.

[Analysis of 18F-FDG uptake pattern in PET for diagnosis of aseptic loosening versus prosthesis infection after total knee arthroplasty. A prospective pilot study]

The AIM of this prospective study was to identify a typical pattern for fluorodeoxyglucose (18F-FDG) uptake in positron emission tomography (PET) to differentiate aseptic loosening (tibial and / or femoral component) from prosthesis infection in painful knee prosthesis.

PATIENTS, METHODS

20 patients with painful knee prosthesis underwent PET imaging to evaluate aseptic loosening / prosthesis infection of their knee prosthesis. The interface between bone and surrounding soft tissue or bone was divided into 3 segments each for both the femur and the tibia and in addition for 4 segments reflecting the surrounding periprosthetic soft tissue. FDG uptake in each of the segments was scored (0-3) by two independent observers. The final diagnosis was based on operative findings with subsequent microbiological culture and histological examination.

RESULTS

After surgical revision 6 femoral components and 5 tibial components were found to be loose and prosthetic infection was present in 9 prostheses. In 8 of 9 infected prostheses loosening of the femoral und tibial component occurred. There was no statistically significant correlation between the standardised uptake within each of the segments and the diagnosis of aseptic loosening or prosthesis infection. A differentiated qualitative and quantitative FDG-PET result interpretation divided into five categories was developed. Specificity / sensitivity / positive predictive value / negative predictive value were 93% / 83% / 83% / 93% for aseptic loosening of the femoral component, 87% / 80% / 67% / 93% for aseptic loosening of the tibial component and 82% / 89% / 80% / 90% for infection.

CONCLUSION

This pilot study shows that FDG-PET is a promising diagnostic tool for patients with painful knee prostheses. There is a good correlation between PET images and the intraoperative and pathology findings. Its clinical value, however, warrants further evaluation in a larger patient population.

[Evaluation of the efficiency of the zero-dose-C-arm navigation approach]

BACKGROUND

The efficiency and success of computer-assisted fluoroscopic navigation systems mainly depend on the quality of the process of image acquisition: obtaining the correct view of anatomic structures, relative orientation of multiplanar X-ray images and the necessary amount of radiation dose. These systems may be optimised by using a system called zero-dose c-arm navigation (ZDCAN). We investigate whether the available computer-assisted systems may be used to navigate the c-arm before image acquisition to obtain X-ray images with maximised accuracy and minimal radiation exposure.

METHODS

Based on position data of an optical tracking system combined with statistical deformable bone models, ZDCAN is able to generate a real-time preview of expected X-ray images of the lower extremities without using radiation. We performed a cadaver study on six full-body specimens comparing the zero-dose approach to conventional positioning of the c-arm in order to evaluate efficiency and accuracy. Eight users acquired two perpendicular X-ray images of the hip, the knee and the femoral diaphysis.

RESULTS

The number of X-ray images required to get a satisfying picture could be reduced to seven using the zero-dose approach; the conventional approach needed 11 images. The mean time did not differ significantly. Regarding the image quality, using ZDCAN quasi-orthogonality could be reached while the conventional approach showed a large variation of the relative orientation.

CONCLUSION

Using ZDCAN, the amount of radiation can be reduced by requiring less X-ray images as well as reaching better accuracy.

Evaluation of a new fluoroscopy-based navigation system in the placement of the femoral component in hip resurfacing

Prosthesis-specific mechanical alignment instruments for the precise and reproducible positioning of the femoral component constitute one of the major improvements in modern hip resurfacing prostheses. However, mechanical failure of the femoral component is mostly attributable to the surgical technique, and in particular to notching of the femoral neck. In order to evaluate a novel computer-assisted fluoroscopy-based planning and navigation system, six DUROMTM hip resurfacing prostheses were implanted into artificial femurs by means of computer-assisted fluoroscopy-based navigation and prosthesis-specific mechanical alignment instruments. Subsequently, the planning and navigation system was tested within the scope of a cadaver study on three fixed whole-body preparations (six femurs). The average difference between planned and actual angle of the prosthesis was 0±0.7° for fluoroscopy-based navigation versus 6.5±7.8° for the in-vitro use of the prosthesis-specific mechanical alignment instruments, and 1±1.4° for fluoroscopic navigation in the cadaver study. The average discrepancy between planned and actual anterior offset was −1.2±1.2 mm versus 0.8±4 mm, and 0.3±2.2 mm in the cadaver study, and the time required for the total of five planning and navigation steps was 17.2±1.5 min versus 14±0.8 min and 20.2±2.5 min respectively. No notching of the femoral neck occurred under fluoroscopy nor under conventional treatment. During in-vitro studies, use of the computer-assisted fluoroscopy-based planning and navigation system resulted in enhanced accuracy compared with conventional prosthesis-specific mechanical alignment instruments. The system has yielded initial promising results within the scope of the cadaver study.

[Silicate coating of cemented titanium-based shafts in hip prosthetics reduces high aseptic loosening]

AIM

For cemented hip prostheses, all requirements can be fulfilled by using forged Co/Cr/Mo stems. Co/Cr/Mo alloys, however, are contraindicated for allergy sufferers. For these patients, a cemented prosthesis made of titanium (alloy) would be indicated. Cemented stems from titanium (alloy), depending on the geometry of the prosthesis and its specific surface texture, however, may have loosening rates which are clinically not tolerable. In comparison to Co/Cr/Mo alloys, the greater roughness in conjunction with lesser abrasion resistance of titanium-based alloys leads to high loosening rates caused by abrasion. On the other hand, the greater surface roughness permits good mechanical retention of bone cement to the surface. Good mechanical retention enhances migration behaviour and reduces micromotions. However, there is no stable hydrolytic bond between bone cement and metallic surface; intermediate-term debonding between metal and bone cement is predictable. This debonding results in relative movements, consequently in wear particles which have their origin both from the rough metallic surface and from the PMMA cement. The roughness of the metallic surface operates as emery and with that, a rubbing wear from the PMMA.

METHOD

For the above reasons, a low or moderate roughness is essential for easily abradable implants such as shafts made of titanium (alloy) because low roughness provides a fail-safe running function in case of debonding. Thus, one must allow for inappropriate migration behaviour accompanied by greater micromotions due to insufficient mechanical retention in the case of low roughness. This can be accomplished by a silicate layer coating applied to the metal shaft surface via electrochemical "ECD" or physical vapour deposition "PVD". For analysis, specimens (screws for pull-out, cones for push-out tests) were sand-blasted, so that roughnesses between Ra = 0.8 microm (Rz = 4 microm) and Ra = 2.0 microm (Rz = 9 microm) were generated.

RESULTS

The bond strengths observed in tensile tests for roughnesses of Ra = 1.7 mm were always well above 25 MPa for all periods of hydrolytic load. Therefore, the investigation shows that surfaces of moderate roughness (Ra = 1.7 microm), however coated, provide a steady retention. Cave-in and micromotions should widely be prevented.

CONCLUSION

The abrasion, which is a consequence of and reason for debonding and loosening at the same time, should be avoidable if the bonding of cement on the metallic shaft is stabilised with the help of a suitable chemical bond system.

[Perineural cysts causing severe back pain and pathological fracture of the massa lateralis of the sacrum]

We report on the case of an 81-year-old woman who was hospitalised because of severe pain at the sacro-iliacal joint radiating into the left leg without any accompanying neurological defect. X-rays demonstrated a step in the left massa lateralis of the sacrum, thus CT scans and MRI were performed, and multiple perineural cysts (Tarlov's cysts) were found. The patient underwent microsurgical treatment by fenestration of the cyst wall and evacuation of the fluid content in order to avoid further expansion of the cysts. Under consequent treatment with pain killers, complete mobilisation of the patient could be achieved. Ambulant follow-up by clinical controls and X-rays demonstrated a substantial resolution of the patient's preoperative symptoms. Symptomatic perineural cysts should be included into differential diagnosis of severe low back pain, thus CT or MRI scans should be performed in case of long-lasting or intrackable pain.

[Intravertebral pressure during vertebroplasty - an in-vitro study]

INTRODUCTION

Extravasation of bone cement into the vertebral venous system during cement injection has been reported to be a major complication of percutaneous vertebroplasty. Therefore, high injection pressures during cement application into the fractured vertebral body are considered as one possible cause of cement leakage or extravasation. The aim of the current study was to measure the increase in intravertebral pressure caused by cement injection during vertebroplasty compared to the baseline venous pressure for the ascending lumbar vene.

MATERIAL AND METHODS

In context of a cadaver study of 19 unfixed lumbar cadaver spines (L2-L5) [9 female, 10 male, 72 +/- 4.1 years] 19 vertebroplasties have been performed under operative conditions through a transpedicular approach. A manometer was placed in the lateral corticalis of each vertebral body for dynamic pressure measurement during 4 cement application cycles. Average and maximal intravertebral pressures as well as the average intravertebral pressure over the time of cement application ["area under the curve" (AUC)] were calculated.

RESULTS

Average intravertebral pressure (10.9 +/- 12.6 kPa [min.: - 15.2 +/- 24.7 kPa; max.: 56.1 +/- 70.1 kPa]) showed a 13.6-fold increase compared to the baseline venous pressure for the ascending lumbar vein and a 70-fold increase compared to maximal pressure. During the 4 cement application cycles a continuous increase of the average intravertebral pressure over the application cycle (AUC) occurred.

CONCLUSION

The 13.6-fold increase in intravertebral body pressure caused by cement injection during percutaneous vertebroplasty in comparison to the baseline venous pressure for the ascending lumbar vein might be one possible cause of the high rate of extravasation of bone cement reported in the current literature.

[Optical coherence tomography (OCT) to evaluate cartilage tissue engineering]

AIM

The aim of this study was to investigate hyaline cartilage defects treated with cell-seeded artificial matrix systems (two different collagen type I gels) with the method of optical coherence tomography (OCT) and to correlate the results with conventional histological and immunocytochemical staining.

METHOD

Osteochondral blocks were harvested from 20 patients undergoing total knee replacement and trimmed to 2 x 2 cm. Under sterile conditions, chondral defects of 8 mm diameter were either filled with a collagen type I gel plug seeded with autologous chondrocytes (2 x 10 (5)/mL gel), or with a corresponding gel plug which was stabilised by a 20-fold compression. Of each group, 5 specimens were cultivated for 6 weeks under standardised in vitro conditions (37 degrees C, 5 % CO (2), humidified atmosphere), while the remaining 5 specimens were implanted subcutaneously in nude mice (BALBc -/-). Immediately after recovery, the repair tissue and bonding zones were investigated by OCT. Subsequently, specimens were decalcified and investigated by H&E staining and collagen type II immunostaining. The results of OCT and conventional staining were correlated.

RESULTS

By OCT, repair tissue could be investigated up to 1.6 mm in depth, physically limited by the utilised OCT system. In the denser hyaline cartilage regions, OCT resolution was reduced. Regardless of cultivation (in vitro or nude mouse), ultrastructural features of the repair tissue could be demonstrated. In particular, ultrastructural differences between the two investigated collagen gels could be detected. Moreover, the bonding region between repair tissue and hyaline cartilage could be evaluated by OCT investigation. The results of the OCT measurements were confirmed by H&E and collagen type II immunostaining.

CONCLUSION

By OCT, repair tissue generated by the treatment of cartilage defects with tissue-engineered matrix systems could be evaluated in vitro. Future studies may show if repair tissue quality may be monitored in situ by OCT.

Surface coating to improve the metal-cement bonding in cemented femur stems

INTRODUCTION

Hydrolytic debonding of the metal-cement interface is one of the main reasons for aseptic loosening in cemented hip arthroplasty.

MATERIALS AND METHODS

BiContact femur stems (CoCrMo-/TiAl6V4-alloy) were coated by a silica/silane interlayer coating system. The stems were cemented into artificial femurs. The cyclical loading (DIN ISO 7206-4) was performed within a hip-simulator. Uncoated stems (CoCrMo-/TiAl6V4-alloy) were prepared and loaded the same way. After loading, the metal-cement and the bone-cement interfaces were analysed. Unloaded uncoated and unloaded coated BiContact stems served as a control.

RESULTS

The coated loaded stems showed a significant reduction in debonding and cement failure (P < or = 0.05). A high correlation was documented between debonding and cement failure (rSpear> or = 0.9). There was no significant difference between CoCrMo- and TiAl6V4-stems (P > or = 0.05).

CONCLUSION

The silica/silane coating significantly decreased hydrolytic debonding at the metal-bone cement interface with consecutively less cement failure.

[Surface pretreatment of endoprostheses by silica/silane to optimise the hydrolytic stability between bone cement and metal. Total hip and knee arthroplasty]

BACKGROUND

The aseptic loosening of cemented total hip and knee arthroplasties is still an unsolved problem. In this regard, the hydrolytic resistance in the metal-to-bone cement interface is of major importance.

METHODS

Cemented pretreated femur stems and tibia components coated by means of a silica/silane interlayer system were dynamically loaded with the help of a hip and knee simulator similar to DIN ISO Norm. After loading, the components were microscopically analysed concerning both debonding in the metal-to-bone cement interface and cement mantle defects. These data were matched with uncoated components. Unloaded coated and uncoated femur and tibia components acted as controls.

RESULTS

Compared with uncoated components, the pretreated and coated ones yielded a significant reduction in cement defects as well as of debonding in the metal-to-bone cement interface.

CONCLUSION

Using the silica/silane interlayer system for cemented femur and tibia components, hydrolytic debonding in the metal-to-bone cement interface with following cement mantle failure can be reduced. This could help increase the long-term stability of the metal-to-bone cement compound, with decreased aseptic loosening.

[Functionality and accuracy of a fluoroscopic navigation system in the placement of the femoral component for hip resurfacing - a cadaver study]

INTRODUCTION

Resurfacing arthroplasty represents an alternative method to total hip replacement especially for the young and active patient. The main reasons for early implant failure are mal-positioning of the femoral component and notching of the femoral neck during femoral head preparation.

MATERIAL AND METHODS

In the context of a cadaver study of formalin-fixed cadaveric full body specimens 6 DUROM -Hip-Resurfacing prosthesis have been implanted under navigation control. The aim of the study was an evaluation of the functionality and accuracy of the computer-assisted planning and navigation system on the basis of a navigation module library from Surgitaix AG Aachen, Germany.

RESULTS

The main angulation error between planning (135.2 +/- 3.6 degrees ) and navigation (136.2 +/- 2.8 degrees ) was 1.9 +/- 1.1 degrees , the main anterior offset error between planning (2.2 +/- 1.3 mm) and navigation (2.7 +/- 2.3 mm) was 1.2 +/- 1.9 mm. The main distance error between planning and navigation was 2.7 +/- 1.3 mm. The mean time for all five planning and navigation steps was 20.2 +/- 2.5 min. Against the background of a acetabular bone-saving approach in all 6 cases the smallest possible femoral component could be implanted.

CONCLUSION

The computer-assisted fluoroscopic planning and navigation system for hip resurfacing showed within the scope of this cadaver study first promising results. The system approaches a practicable intraoperative planning with a high accuracy in operative implementation. Nevertheless, the potential benefit has to be evaluated in further clinical studies, especially from the perspective of a possible integration of this navigation system into the clinical work-flow. Further studies should consider a fluoroscopic-assisted range of motion assessment under consideration of an additional cup-module to enhance the postoperative range of motion after hip resurfacing procedures.

[Clinical results after three years use of matrix-associated ACT for the treatment of osteochondral defects of the knee]

AIM

The aim of this study was to examine the clinical results after the treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation (ACT).

METHOD

In this study 13 patients with osteochondral defects of the knee (12 femoral, 1 tibial) with OCD ICRS grade IV or ICRS grade IV B were included. The osteochondral defects were reconstructed simultaneously with autologous monocortical cancellous bone cylinders or chips from cancellous bone and matrix-supported autologous chondrocyte transplantation (CaReS). Data were analysed in accordance with the ICRS criteria and the Brittberg score. Patients were followed up to 36 months after the operation.

RESULTS

The average age of the patients was 34.9 (16 - 47) years at the time of surgery. The size of the defect was 8.1 (3.8 - 13.5) cm(2). The subjective and objective IKDC scores, the Brittberg and the ICRS function score were statistically significantly improved during the observation time. In one patient the transplantation failed and another patient was not available for the follow-up at 36 months. The objective IKDC score and the ICRS function score increased from 0/13 (0 %) to 11/12 (91.7 %) in categories A and B, or I and II, respectively, after 3 years. At this point of time 83.4 % (10/12) of the patients voted the treatment as excellent or good. The subjective IKDC score improved from 38.4 (+/- 12.7) preoperatively to 66.1 (+/- 17.0) after 3 years.

CONCLUSION

The treatment of osteochondral defects of the knee with autologous bone grafting and matrix-supported autologous chondrocyte transplantation shows promising results even for larger defects. But for a final decision about this therapy the present sample size was too small. There is a need for further long-term investigation with a larger number of patients.

A novel rat tail collagen type-I gel for the cultivation of human articular chondrocytes in low cell density

Collagen type-I matrix systems have gained growing importance as a cartilage repair device. However, most of the established matrix systems use collagen type-I of bovine origin seeded in high cell densities. Here we present a novel collagen type-I gel system made of rat tail collagen for the cultivation of human chondrocytes in low cell densities. Rat tail collagen type-I gel (CaReS, Arthro Kinetics, Esslingen, Germany) was seeded with human passage 2 chondrocytes in different cell densities to evaluate the optimal cell number. In vitro, the proliferation factor of low density cultures was more than threefold higher compared with high density cultures. After 6 weeks of in vitro cultivation, freshly prepared chondrocytes with an initial cell density of 2x10(5) cells/mL showed a proliferation factor of 33. A cell density of 2x10(5) cells/mL was chosen for in vitro and in vivo cultivation using the common nude mouse model as an in vivo system. Chondrocytes stayed viable as a Live/Dead fluorescence assay and TUNEL staining revealed. During in vitro cultivation, passage 0 cells partly dedifferentiated morphologically. In vivo, passage 0 cells maintained the chondrocyte phenotype and demonstrated an increased synthesis of collagen type-II protein and gene expression compared to passage 2 cells. Passage 2 cells did not redifferentiate in vivo. Cultivating a cell-seeded collagen gel of bovine origin as a control (AtelocollagenTM, Koken, Tokyo, Japan) did not lead to superior results with regard to cell morphology, col-II protein production and col-II gene expression. With the CaReS collagen gel system the best quality of repair tissue was obtained by seeding freshly isolated chondrocytes.

[Mechanical bending strength of explanted ex vivo bone cements compared with in vitro samples]

INTRODUCTION

The mechanical properties of acrylic bone cements are an important factor in determining an efficient load transmission between prosthesis and bone to guarantee the long-term stability in cemented hip arthroplasty.

MATERIAL AND METHODS

Palacos and Refobacin Palacos specimens from 21 aseptically loosened femoral compoments of cemented hip arthroplasties manufactured by the first to third generation cementing technique have been mechanically tested in a standardised four-point bending test (ISO 5833). In vitro manufactured Palacos and Refobacin Palacos specimens served as a control group. The fatigue fracture surfaces were morphologically analysed with light microscopy.

RESULTS

Under in vitro conditions manufactured specimens had higher values of bending strength, with the exception of blood contaminated ones, compared to ex vivo specimens. Ex vivo specimens of the second and third generation cementing technique had higher values than specimens of the first generation.

CONCLUSIONS

Acrylic bone cements are subjected to a multifactorial material fatigue in vivo. Here, the art and quality of cementing technique is of eminent importance in determining the long-term stability of cemented hip arthroplasty.

[Soft-tissue management in primary knee arthroplasty: common techniques, navigation and force-sensing devices]

Soft-tissue management is essential for the outcome in total knee arthroplasty. In combination with osseous resections and component positioning, correction of the underlying ligamentous dysbalance should yield a stable joint throughout the flexion arc. Different "philosophies" with regard to technique, timing and tactics in ligament balancing are described. So far, surgeons have not been provided with standardised devices that allow the objective measurement of this complex issue. Moreover, knowledge concerning the "ideal" soft-tissue stability following knee arthroplasty is still sparse. As part of the scientific project "OrthoMIT" (minimal invasive orthopaedic therapy) an approach to combine conventional soft-tissue management with navigation and force-sensing devices should be realized technically. The aim is to develop an instrument for the objective measurement of soft-tissue management in scientific and clinical applications.

[Application of an amphiphilic bonder in a goat model to increase the femoral cement-bone adhesion in cemented hip arthroplasty]

AIM

Cemented revision of femoral components in total hip arthroplasty has shown high rates of early loosening due to reduced micro- and macroretention of the cement to the endostal bone stock. Enhanced stability can be reached by an amphiphilic bonder, which offers a covalent bonding of the hydrophobic cement to the hydrophilic bone. The aim of this study is to evaluate the biocompatibility of such a bonder and its effects on the mechanical stability of cemented hip arthroplasty stems in vivo.

METHODS

Total cemented hip arthroplasties were performed in 20 sheep. In the verum group (n = 10) the implant bed was preconditioned by application of the bonder prior to femoral stem implantation. To study the biocompatibility around the bone-cement interface fluorescent marking of osteoblasts was applied in vivo throughout the observation period of 9 months. Native X-rays of the hip joints were obtained immediately after implantation and after euthanasia. The bone-cement interface was examined histologically.

RESULTS

All stems of the verum group showed firm bonding of cement to bone in manual testing, while in 7 of the 10 controls the stems with adherent cement could be easily pulled out off the bony implant bed. This was coherent with significantly higher rates of progredient radiolucent lines and soft-tissue interpositions between bone and cement in the control group. The bonder was biocompatible.

CONCLUSION

When preconditioned with an amphiphilic bonder, cemented stems showed a markedly higher adhesive strength to the cancellous bone without signs of inflammation or neoplasia. This procedure might offer enhanced longevity of cemented femoral revision stems in hip arthroplasty.

Computer-assisted single- or double-cut oblique osteotomies for the correction of lower limb deformities

Corrective osteotomy interventions on lower extremities are widely accepted procedures for restoring axial alignment of lower limbs. However, some studies reveal failure rates of up to 70 per cent in a 10 year time frame, which indicates that the success of corrective osteotomies depends on multiple factors. Based on a comprehensive review of error sources among conventional correction osteotomy interventions, a novel approach was developed in order to reduce these error sources among all clinical working steps (deformity determination, planning, and intra-operative realization). The article describes the implemented methodology for realizing optimal correction osteotomies based on a six-dimensional or 12-dimensional optimization module for single- and double-cut oblique osteotomies. The results show that the realized planning and navigation concept enables reduction in the error sources among the clinical working steps of correction osteotomy interventions.

[Correction osteotomies near the knee and navigation: state of the art within the scope of the "OrthoMIT" project for the development of an integrated platform for smart interventional orthopaedic surgery and traumatology]

INTRODUCTION

"OrthoMIT--minimal invasive orthopaedic therapy" is a project to develop an integrated platform for less invasive operative procedures in hip, knee and spine surgery, supported by the German Federal Ministry for Education and Research (BMBF). Twenty-seven industrial and clinical partners under the management of the Orthopaedic Department of the University Hospital Aachen (Prof. Dr. F. U. Niethard) intend to develop in 10 subprojects innovative aspects and modules of the "OrthoMIT" system.

MATERIALS AND METHODS

Within the project and amongst other procedures, joint-preserving correction osteotomies have been analysed to develop planning and navigation tools on the basis of improved and less invasive surgery. Therefore, the reproducibility and validity of the conventional methods were investigated and compared with the technical possibilities in computer-guided planning and navigated surgery for correction osteotomies of the upper extremities. Clinical needs, necessary innovative aspects and modules were defined out of these consolidated findings and passed on to the industrial partners of the "OrthoMIT" project to develop innovative techniques in the field of planning and navigation.

CONCLUSION

The present article reports in a concise way about the essentials of the available current techniques in correction osteotomies of the upper extremities with the main focus being placed on navigation.

Durom™-Hip-Oberflächenersatz am Hüftgelenk: Erste klinische Ergebnisse mit dem lateralen Zugang

INTRODUCTION

We present the first clinical and radiographic results of the Durom Hip Resurfacing prosthesis with a lateral approach.

MATERIALS AND METHODS

52 patients (n = 59 protheses) with a mean follow-up of 25.4 +/- 10 month were evaluated. Clinical evaluation was done using the Harris hip score (HHS), a modified University of California at Los Angeles (UCLA) Activity Level Scale and the Merle d'Aubigné Score pre- and postoperatively. Radiographic evaluation included the preoperative femoral neck-shaft angle, the pre- and postoperative femoral offset, the postoperative stem-shaft angle as well as postoperative periprosthetic radiolucencies.

RESULTS

Within the clinical follow-up the postoperative mean HHS (93 +/- 4.3 vs. 41.2 +/- 7.1 points), the modified UCLA (8.8 +/- 2.8 vs. 4.8 +/- 1.9) as well as the Merle d'Aubigné Score (17.1 +/- 1.7 vs. 7.5 +/- 2.1) indicated a significant improvement (p <or= 0.05) compared to the preoperative evaluation. In 98.2 % a firm bony ingrown of the components without any radiolucency was observed. The average deviation of the preoperative physiological femoral neck-shaft angle (135.5 +/- 3.4 degrees) compared to the postoperative stem-shaft angle (141.3 +/- 4.8 degrees) was 5.8 +/- 2.6 degrees. The mean postoperative femoral offset was reduced by 2.5 mm. At follow-up 2 hips (3.5 %) were revised due to femoral neck fracture (n = 1) and to heterotopic ossifications (Brooker III) (n = 1).

CONCLUSION

The Durom Hip Resurfacing prosthesis is a promising alternative for the young and active patient. The real medical and economical benefit has to be evaluated in further examinations.

Improvement of the long-term adhesive strength between bone cement and bone in cemented cup arthroplasty: ex-vivo study

INTRODUCTION

One of the main causes of cup loosening in cemented total hip replacement is the lack of a hydrolysis stable compound between the hydrophobic bone cement and the hydrophilic acetabular bone stock. Thus, the long-term adhesive strength between bone and bone cement is decreased resulting in premature aseptic loosening. Accordingly, an amphiphilic bonding system was developed to prevent hydrolytic debonding in the interface bone-to-bone cement.

MATERIALS AND METHODS

Polyethylene cups were cemented in cadaver sheep hips. The hips were prepared with (n = 10) a multilayer bonding system as well as with an improved monolayer bonding system with (n = 10) and without (n = 10) UV-light hardening. The hips were dynamically loaded (10(6) cycles; 3 Hz; upper/lower load 1,500/200 N) and afterwards turned out with a defined strength to determine the interface compound strength. Dynamically loaded cemented cups without using the bonding system (n = 10) function as a control group.

RESULTS

The interface adhesive strength improved significantly by a factor of 1.9 (using the multilayer bonding system) compared to the unconditioned ones (P < or = 0.05); for the monolayer bonding system without (with) UV-light hardening the compound strength was 11.9-fold (> or =22.2-fold) higher (P < or = 0.001).

CONCLUSION

The bonding system significantly improves the adhesive strength between bone and bone cement in cemented cup arthroplasty.

[Immunohistochemical analysis of periprosthetic osteolysis in aseptic loosening of hip arthroplasty]

AIMS

The main complication in total hip arthroplasty is aseptic loosening. Wear-induced inflammatory processes lead to periprosthetic granulation tissue, which induces bone degradation due to aseptic osteolysis. At the site of bone degradation,the cell populations have not been further analysed so far. Therefore, the present study was designed to analyse bone degradation tissue in comparison to periprosthetic granulation tissue.

METHODS

Tissue specimens of 14 patients with failed modular cup components of cementless total hip arthroplasties were obtained during revision surgery. Immunohistochemistry was performed by using anti-CD 31 (endothelial cells),anti-CD 45 (granulocytes and lymphocytes) and anti-CD 68 antibodies (mononuclear phagocyte system, MPS). Fibroblasts and osteoblasts were immunohistochemically distinguished as CD 31/45/68-negative cells. Semiquantitative analyses,including a morphometric study, were then performed both in the bone degradation zone and in the periprosthetic granulation tissue.

RESULTS

At the site of bone degradation, the majority of cells belonged to MPS (73.6 +/- 3.31%),while fibroblasts were significantly less frequent (9.6 +/-1.67%). A distinct population of endothelial cells (7.75+/- 1.4%) as well as lymphoplasmacellular cells (5.75+/-2.35%) were observed. In addition,only a small amount of neutrophilic granulocytes (0.7 +/- 0.4 %) were detected. In the periprosthetic granulation tissue, findings were very similar to those of the bone degradation zone,with the exception of higher amounts of fibroblasts (15.69 +/- 2.74%).

CONCLUSIONS

This study confirms that, in aseptic hip arthroplasty loosening, the majority of cells detected at the site of bone degradation are of the MPS, which are predominantly involved in osteolytic processes. There is no pathologically significant difference between the cell population of periprosthetic granulation tissue and granulation tissue at the sites of bone degradation.

[The morse taper junction in modular revision hip replacement]

Morse taper junctions of modular hip revision replacements are predilection sites for fretting, crevice corrosion, dissociation and breakage of the components. In this report we present the results of a retrieval analysis of a morse taper junction of a MRP-titanium modular revision replacement (MRP-Titanium, Peter Brehm GmbH, Weisendorf, Germany) after 11.5 years of in vivo use. In the context of this case report the significance of morse taper junctions in modular hip revision replacement under consideration of the current literature is also discussed.

Die Behandlung femoropatellarer Knorpelschäden mit einem dreidimensionalen Kollagengel: Klinische Ergebnisse im Zwei-Jahres-Verlauf

AIM

Here we present first clinical results of the treatment of patellofemoral cartilage lesions with a 3D collagen gel (CaReS).

METHODS

Isolated patellofemoral cartilage lesions in 14 patients (13 patellar, 1 trochlear) were treated by matrix-based ACT using a collagen gel seeded with autologous chondrocytes. In this study, only those patients were taken into account who complied with the inclusion criteria of the German working group "tissue regeneration and tissue substitutes". Data were analysed in accordance with the ICRS criteria and the Brittberg score. We present the 2-year postoperative clinical follow-up.

RESULTS

After 2 years the ICRS-IKDC and Brittberg scores revealed a statistically significant improvement. The preoperative rating of the objectiveIKDC and functional ICRS score improved from 0/14 and 2/14 (14.3%) to 11/14 (78.6%) in the categories A/B and I/II, respectively. 11 Patients(78.6%) judged the clinical outcome as excellent or good. The subjective IKDC score improved from 32.4 +/- 8.4 prior to operation to 67.8 +/- 27.4 at the 2-years follow-up.

CONCLUSION

The use of 3D matrix systems could represent a promising improvement of conventional ACT in the treatment of patellofemoral cartilage lesions, but the results have to be verified by long-term investigations.

In vivo cultivation of human articular chondrocytes in a nude mouse-based contained defect organ culture model

The nude mouse model is an established method to cultivate and investigate tissue engineered cartilage analogues under in vivo conditions. One limitation of this common approach is the lack of appropriate surrounding articular tissues. Thus the bonding capacity of cartilage repair tissue cannot be evaluated. Widely applied surgical techniques in cartilage repair such as conventional and three-dimensional autologous chondrocyte implantation (ACI) based on a collagen gel matrix cannot be included into nude mouse studies, since their application require a contained defect. The aim of this study is to apply an organ culture defect model for the in vivo cultivation of different cell-matrix-constructs. Cartilage defects were created on osteochondral specimens which had been harvested from 10 human knee joints during total knee replacement. Autologous chondrocytes were isolated from the cartilage samples and cultivated in monolayer until passage 2. On each osteochondral block defects were treated either by conventional ACI or a collagen gel seeded with autologous chondrocytes, including a defect left empty as a control. The samples were implanted into the subcutaneous pouches of nude mice and cultivated for six weeks. After retrieval, the specimens were examined histologically, immunohistochemically and by cell morphology quantification. In both, ACI and collagen gel based defect treatment, a repair tissue was formed, which filled the defect and bonded to the adjacent tissues. The repair tissue was immature with low production of collagen type II. In both groups redifferentiation of chondrocytes remained incomplete. Different appearances of interface zones between the repair tissue and the adjacent cartilage were found. The presented contained defect organ culture model offers the possibility to directly compare different types of clinically applied biologic cartilage repair techniques using human articular tissues in a nude mouse model.

Das Verletzungsmuster nach Einführung der A-Junioren-Fußball-Bundesliga in Deutschland im Vergleich zum Senioren-Profi-Fußball

In 2003 the junior soccer premier league (U19) has been introduced in Germany to increase the competitive level in this group of age (16 - 18 years). It is the aim of this study to compare the injury pattern accompanying this new league of semi-professional junior soccer with a professional senior team. In a retrospective study all traumatic and overuse injuries, responsible for absence from practice or matches, which occurred in two seasons of one junior premier league team were recorded and analyzed. These data were compared to the injury pattern of a professional senior team based on a one-season survey. Overall, more traumatic than overuse injuries were seen. The lower extremity was predominantly affected by both. The ankle joint was the most injured joint. An injury rate of 2.89 per 1000 hours of soccer was calculated for the juniors and 2.35 for the seniors. Junior players missed 15.8 days and seniors 17.1 days of practice or match as result of an injury. Semi-professional junior and professional senior soccer share the same injury patterns with regard to injury rates and types of injuries. Therefore a professional medical care with special emphasis on prophylaxis is warranted in semi-professional junior soccer.

[First clinical experiences with a novel 3D-collagen gel (CaReS) for the treatment of focal cartilage defects in the knee]

AIM

In this prospective study we present a novel technique of matrix-based chondrocyte transplantation for the treatment of focal cartilage defects.

METHOD

22 patients with chondral or osteochondral femoral defects were treated with 3D-collagen type-I gel seeded with autologous chondrocytes (CaReS). Overall handling of this novel method is described, and results after 2 years follow-up with regard to the ICRS-score are presented.

RESULTS

14 patients were treated because of a focal chondral lesion, in 8 cases subchondral bone had to be reestablished. The average defect size was 6 cm(2). In all cases cell-seeded matrix samples could be fixed with fibrin glue without any problems. The average surgery time was 69 min, length of the surgical approach was 8.2 cm. No surgery-specific problems had to be observed. A significant improvement in IKDC-score, functional score and overall rating after 3 or 6 months up to 2 years follow-up was detected. After 2 years post-OP 13 Patients were evaluated and matrix-based defect treatment by CaReS was rated good to excellent by 84.6 % of the patients.

CONCLUSION

Defect treatment with cell-seeded 3D-collagen gel is easy to handle with a good clinical outcome after 2 years follow-up. Further investigations with higher patient number, longer follow-up time and histological and biomechanical sample analysis are needed in order to establish this method as an improvement of conventional ACT.

[Cemented total knee arthroplasties]

INTRODUCTION

The aseptic loosening of cemented total knee arthroplasties is still an unsolved problem. In this regard, the hydrolysis resistance in the metal-to-bone cement interface is of major importance.

MATERIAL AND METHODS

Cemented pre-treated tibia components coated by means of a silica/silane interlayer system of the model "Columbus PS" were dynamically loaded with the help of a knee-simulator similar to DIN ISO 14243. After loading, the components were microscopically analysed concerning debonding in the metal-to-bone cement interface as well as with regard to cement mantle defects. These data were matched with uncoated "Columbus PS" components. Unloaded coated and uncoated tibia components acted as a control.

RESULTS

In comparison with uncoated tibia components, the pre-treated and coated ones yielded a highly significant reduction of cement defects (p < 0.01) as well as a significant reduction of debonding in the metal-to-bone cement interface (p < 0.05).

CONCLUSION

By means of the silica/silane interlayer system for cemented tibia components, a hydrolytic debonding in the metal-to-bone cement interface with subsequent mechanical loosening and consecutive early cement mantle failure can be significantly reduced. This could lead to an increased long-term stability of the metal-to-bone cement compound with decreased aseptic loosening in clinical use.

[Liver laceration following a kick in a soccer game]

Severe intraabdominal injuries in soccer are very rare. We present the case of an 18 year old soccer player who suffered from a grad IV liver laceration following a kick during a soccer game. After primary explorative laparatomy and liver packing in a hospital nearby the patient was transferred to our clinic. Following CT scan the injury was treated by suture of liver parencym lacerations, argon laser coagulation and pile duct repair. In soccer severe intraabdominal injuries should be expected following players collision at high velocity or kicking with the foot or the knee.

[Isolated bilateral Sternocostoclavicular Hyperostosis (SCCH) with a pathological clavicular fracture--a 10-year follow-up]

The presented case demonstrates the clinical and radiological course of a woman suffering from bilateral sternocostoclavicular hyperostosis (SCCH) from early changes to a spontaneous clavicula fracture after 10 years. SCCH is characterised by a chronic recurrent painful swelling of the sternoclavicular region due to an aseptic inflammation and hyperostosis of the clavicula, sternum, upper ribs and the adjacent soft tissues. Frequently the picture is accompanied by cutaneous and other skeletal symptoms. The disease can be part of the SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome. The chronic process is represented by the typical "bull horn sign" in a bone scan. NSAIDS should represent the first line treatment.

[Coxitis fugax--the beginning of Perthes' disease?]

We present the clinical case of a decennial boy with acute leftsided hip pain without appropriate trauma. The initial diagnosis of coxitis fugax was verified in this case with inconspicuous blood parameters and X-ray by a sonographically proven intraarticular effusion. An immediate magnet resonance imaging (MRI) study of the affected hip joint was done. Here, a complete "necrosis" of the proximal femur epiphysis was verified. With knowledge of these results, an immediate operation of the hip joint with a ventral capsule incision and consecutive intraarticular decompression was performed. A complete reperfusion of the femur head was evident in the MRI scan seven days postoperatively. In accordance with this clinical case report, we would like to point out the necessity for the immediate diagnosis of indifferent hip pain by means of MRI, especially for patients in the atypical "critical age" (> or = 8 years) for coxitis fugax. This is discussed under consideration of the possible aetiopathogenesis and the current literature.

Comparison of modern marker proteins in serum and synovial fluid in patients with advanced osteoarthrosis and rheumatoid arthritis

Numerous studies have focused on the significance of modern marker proteins in the synovial fluid of the knee joint and in the serum both, for osteoarthritis (OA) and rheumatoid arthritis (RA). The relationship between the serum concentrations and the concentrations in the synovial fluid is still unclear. Synovial fluid and serum samples were obtained from 13 patients with advanced OA and from 8 patients with severe RA and concentrations of MMP-1, MMP-3, MMP-13, TIMP-1, COMP and MIA/CD-RAP were determined. All values were normalized against the total protein concentrations. Serum concentrations of MMP-13 in the RA-group were statistically higher than the synovial values (P<0.05). MMP-13 was the only marker protein that revealed distinct higher levels in the serum than in the synovial fluid. The study design allows only conclusions about advanced stages of RA and OA. Longitudinal investigations may provide further information about the value of MMP-13 as a potential marker to monitor the course of RA and OA.

Diagnostic values of positron emission tomography versus triple-phase bone scan in hip arthroplasty loosening

INTRODUCTION

The most frequent complications of total hip arthroplasty are septic and aseptic wear-induced loosening. A reliable differentiation between septic and aseptic loosening with current diagnostic tools is not possible. Therefore, we examined the diagnostic valency of positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) in cases of septic or aseptic hip arthroplasty loosening compared with conventional triple-phase bone scan (TPBS).

MATERIALS AND METHODS

Fifty patients with 70 total hip replacements (symptomatic n=50, asymptomatic n=20) were examined by means of FDG-PET and TPBS to detect septic and aseptic loosening and differentiate between the two. A differentiated algorithm subdivided into categories I-V was developed for FDG-PET. Additionally, standardized uptake values (SUV) were calculated from the lesion with the highest FDG uptake. Interpretations of the TPBS were done according to the criteria described by Wilson. The final diagnosis was based on operative findings including microbiological and histological examinations (n=50), while the remaining asymptomatic arthroplasties (n=20) were integrated into a clinical follow-up (> or =9 months).

RESULTS

Sensitivity/specificity of FDG-PET was 91%/92% (accuracy 91%) compared with 78%/70% (accuracy 74%) for TPBS. A high correlation could be proved between FDG-PET investigation and operative histopathological findings (r(Spear)> or =0.9). No significant differences were found regarding cemented and uncemented implanted hip arthroplasties (p> or =0.05). Calculation of the SUV turned out to be inappropriate as a sole criterion for image interpretation.

CONCLUSION

FDG-PET is a promising, highly accurate examination method to detect polyethylene and metal wear-induced chronic inflammation followed by periprosthetic osteolysis. In addition, FDG-PET has a significantly higher sensitivity and specificity than TPBS for differentiating between aseptic loosening and infection.

Radionuclide imaging of the painful hip arthroplasty: positron-emission tomography versus triple-phase bone scanning

Two major complications of hip replacement are loosening and infection. Reliable differentiation between these pathological processes is difficult since both may be accompanied by similar symptoms. Our aim was to assess the diagnostic ability of triple-phase bone scanning (TPBS) and positron-emission tomography (PET) to detect and differentiate these complications in patients with a hip arthroplasty. Both TPBS and PET were performed in 63 patients (92 prostheses). The radiotracer for PET imaging was (18)F-fluorodeoxyglucose (FDG). Image interpretation was performed according to qualitative and quantitative criteria although the final diagnosis was based upon either surgical findings or clinical follow-up. The sensitivity, specificity and accuracy of PET was 0.94, 0.95 and 0.95 respectively, compared with 0.68, 0.76 and 0.74 for TPBS. We found that an image interpretation based exclusively upon quantitative criteria was inappropriate because of its low selectivity. The histological examination indicated that increased periprosthetic uptake of FDG in patients with aseptic loosening was caused by wear-induced polyethylene particles and the subsequent growth of aggressive granulomatous tissue.

Das Verletzungsrisiko im Jugend- und Juniorenwettkampfkarate

Increasing professionalism in competitive karate has led to a specific injury pattern. The aim of our study was to investigate the injury pattern in junior competitive karate and to evaluate the prophylactic effect of fist padding. During the 4 (th) Junior World Championships of the World Karate Confederation (WKC) 2004 235 karate fights were observed and injury-related data were recorded. Fist padding was used in 183 fights, 52 fights were carried out without. In 22 % of all fights we saw an injury. Most of them were mild injuries of the head and face: 32 bruises of the face (13 with epistaxis), 7 facial lacerations and 3 concussions (mild brain injury). 14 fights were stopped due to an injury. Only in the category male 18 - 20 years a higher rate of injuries was seen without fist padding (shobu ippon) compared to shobu sanbon (with fist padding). The injury pattern of junior competitive karate is comparable to senior karate. Fist padding does not generally reduce the incidence or severity of injuries.

Welche Faktoren beeinflussen das Ergebnis der ACT bei Überschreiten der Indikationsgrenzen?

AIM

The present study evaluates the results of ACT at the knee joint with transgression of the usual spectrum of indications and points out the possible limits of the method.

METHODS

In 20 of a total of 71 patients the indication limits of ACT were exceeded. The clinical follow-up over two years was related to the localisation, size, adjacent cartilage, previous and additional operations and the quality of the transplanted chondrocytes.

RESULTS

The average patient age at time of operation was 41.1 years (24 to 55 years). The average defect size was 7.9 cm (2) (3.75 to 14 cm (2)). In the analysed group outside of the indication limits of ACT half of the patients showed good or excellent results at clinical follow-up after 2 years. 10 patients, however, assessed the clinical situation as fair or poor. Within this group 5 patients showed a minimum of two lesions. In 6 patients the treated defect was not completely surrounded by an adjacent cartilage shoulder. In 7 cases the meniscus at the site of the lesion had been partially removed in a previous operation and osteoarthrosis or kissing lesions were detected in 4 cases. The persistent good cell quality had no negative influence on the postoperative results.

CONCLUSION

The results after ACT are influenced by the adjacent cartilage shoulder, kissing lesions, previous meniscectomy and osteoarthrosis. This may limit the indications of the method.

[Meniscus replacement: current aspects in the field of tissue engineering]

Tissue engineering offers new opportunities for meniscus repair and replacement. In this field different approaches are being studied to genererate a meniscus subsitute by a combination of a matrix scaffold, cells and specific stimuli. MENISCUS REPLACEMENT BY ACELLUAR MATRICES: For meniscus replacement the matrix material has to meet high biomechanical demands. Besides implant geometry, the material properties and a secure intraarticular attachment are important preconditions for implant function. A collagen scaffold has already been applied clinically for partial meniscus replacement. Scaffolds made of synthetic, bioabsorbable polymers and small intestine submucosa have been employed in animal studies. Following implantation, matrices are invaded by cells and undergo a process of remodeling. Formation of fibrocartilage repair tissue has been observerd. The biomechanical quality of implants and their effect on cartilage preservation have to be studied further. CELLULAR SEEDING OF MATRICES FOR MENSICUS REPLACEMENT: Advanced biological and biomechanical implant quality might be achieved by seeding matrices with cells in vitro. However, the ideal type of cell for this purpose has not yet been identified. Autologous mensicus cells, articular chondrocytes and mesenchymal stem cells represent possible cellular sources. Additional stimuli, such as cytokines and mechanical forces, and techniques of genetic engineering might further contribute to enhance the quality of engineered tissue.

Die zementfreie modulare MRP-Hüftrevisionsschaftendoprothese im „klinischen Follow-up”

INTRODUCTION

We present prospective medium-term results of the modular revision prostheses "MRP-TITANIUM".

MATERIAL AND METHODS

45 patients (n = 48 prostheses) were evaluated. The mean follow-up was 4.7 years (min.-max.: 1.0-9.0 years). Pre- and postoperatively the Harris hip score (differentiated to Paprosky I-III) was examined. 66.67 % of the cases had extensive bony defects (> or = Paprosky II b). By means of X-ray examinations, the stability of the prostheses, periprosthetic bone remodelling, the presence of radiolucent lines as well as bone defect regeneration were assessed postoperatively.

RESULTS

The mean Harris hip score improved from 25.6 preoperative to 71.4 postoperative (p < or = 0.05). In 44 cases the X-ray showed stable fixation without secondary migration. In one case the stem (stand time 2.36 years) was revised due to secondary migration (> or = 5 mm). The survival rate (Kaplan-Meier) was 97 %. Bone transplantation with consecutive defect regeneration was (n = 30) complete in all cases. In six cases (12.5 %) a postoperative dislocation occurred with subsequent successful closed reposition four times (8.3 %). In two cases (4.2 %) an open reposition was done with correction of the antetorsion angle of the prostheses.

CONCLUSION

The "MRP-TITANIUM modular revision prostheses" has proved to be reliable in cases of revision surgery with extensive bony defects. The failure rate was 2.1 % for 48 prospectively examined prostheses.

[[F-18]-fluorodeoxyglucose (FDG) positron emission tomography (PET) as a diagnostic for hip endoprosthesis loosening]

AIM

The purpose of this study was to examine the FDG-PET in respect of its diagnostic valency with regard to septic/aseptic loosening of lower limb prostheses.

METHOD

28 patients with 41 lower limb prostheses were examined by means of FDG-PET to evaluate septic/aseptic loosening of their hip prostheses. Therefore, a differentiated FDG-PET result interpretation subdivided into five categories was developed. The final diagnosis was based on operative findings with following culture and histological outcome.

RESULTS

The worked-out categories showed a high agreement to the intraoperative macroscopic and histological results (n = 23 correctly positive, n = 1 false positive, n = 1 correctly negative and n = 3 false negative).

CONCLUSION

With a subtly differentiated interpretation (categories I - V) of the qualitative glucose metabolism safe statements can be made regarding septic/aseptic endoprostheses loosening. This was impressively confirmed by the agreement of the FDG results with the histological results.

[Competitive karate and the risk of HIV infection--review, risk analysis and risk minimizing strategies]

Bleeding facial injuries are not uncommon in competitive karate. Nevertheless, the risk of an infection with HIV is extremely low. Guidelines about the prevention of HIV infections are presented. Especially in contact sports and martial arts the athletes, judges and staff have to recognize and employ these recommendations. Bleeding wounds of the hands due to contact with the opponents teeth can be minimized by fist padding.

[Teutschländer disease. A rare benign differential diagnosis of proliferative space-occupying lesions in the periarticular soft tissue]

The tumoral calcinosis (synonym: Teutschländer disease) is a very rare benign metabolic dysfunction of unknown etiology. It manifests principally as massive subcutaneous soft tissue deposits of calcium phosphate near the large joints and is also characterized by slow progressive growth. Causally, a disturbance of the calcium and phosphate metabolism/balance with, among others, autosomal dominant heredity is suspected. It appears frequently in the black African population in all age groups, but preferentially in the 1st and 2nd decades of life. Medical help is most frequently sought because of increasing tumor size causing displacement and consecutive pain as well as decreased joint play. We present here a case of Teutschländer disease in a 50-year-old woman on long-term hemodialysis and describe the clinical, radiological, and pathological signs of this rare disease. Subsequently, speculative etiology, differential diagnostic considerations as well as the therapeutic interventions for tumoral calcinosis are discussed taking into consideration the current literature.

[Analysis of (18)F-FDG uptake patterns in PET for diagnosis of septic and aseptic loosening after total hip arthroplasty]

AIM

Identification of typical patterns for fluorodeoxy-glucose (FDG) uptake in positron emission tomography (PET) to detect aseptic loosening of hip prosthesis (ace-tabular and/or femoral component) and prosthetic infection.

METHODS

18 patients with painful hip prosthesis underwent PET using a dedicated full ring scanner after application of 200-300 MBq FDG. The interface between bone and surrounding soft tissue or bone as displayed on coronal slices was divided into 12 segments in accordance with the classifications of Delee and Gruen. FDG uptake in each of the segments was scored (0-3) by two independent observers. Intraoperative findings were regarded as the gold standard.

RESULTS

After surgical revision 14 acetabular components and 9 femoral components were found to be loose and prosthetic infection was present in 7 prostheses. Loosening of the acetabular component was correlated to enhanced uptake in the middle of the acetabular interface, while loosening of the femoral component was correlated to enhanced uptake in the proximal and middle segment of the lateral femoral interface and the proximal segment of the medial femoral interface. A similar pattern was found in prosthetic infection with high uptake along the middle portion of the lateral femoral interface. In 6 of 7 infected prostheses loosening of the acetabular and of the femoral component was present. Taking the typical uptake patterns as criteria for loosening and grade 3 uptake as an additional criterion for septic loosening the accuracy of PET imaging in the detection of loosening of the acetabular or the femoral component and of prosthetic infection was 72, 78 and 89%, respectively.

CONCLUSION

This pilot study presents FDG-PET as a promising diagnostic tool for patients with painful hip prostheses. Its clinical value should be evaluated in a larger patient population.

[FDG PET as an early nuclear medical diagnostic tool for aseptic wear-induced loosening of hip joint endoprostheses--a report of two cases]

To date, 2-[F-18]fluoro-2-deoxy-D-glucose PET (FDG PET) is used as a tool in oncology as well as myocardiological and cerebral functional diagnostics in the clinical routine. False positive results of tumor search imply new possibilities for use in diagnostics of inflammation. The two case reports presented here on aseptic loosening of endoprostheses caused by the rub of polyethylene with histological and immunohistological refurbishing call attention to the possible diagnostic valency of FDG PET as an early warning system regarding aseptic artificial limb loosening induced by the rub of polyethylene. By quantification of glucose metabolism with the "standard uptake value" (SUV) as well as specific storage samples from around the artificial limb, it is the aim of our study group in further examinations to develop an algorithm which permits to distinguish between septic and aseptic loosening.

[Acute retrocecal appendicitis caused by an Actinomyces israelii mixed infection]

We report the rare case of a retrocecal appendicitis in an adult caused by an Actinomyces israelii mixed infection. Suspecting an acute appendicitis the explorative laparotomy was performed. Appendectomy with extensive drainage of the abscess and subsequent high-dose penicillin therapy over several months were the definitive treatment, resulting in complete healing. Special features of clinical symptomatology and problems concerning diagnosis and differential diagnosis are discussed.