[Extension first technique for TKA implantation]. / Die Extension-First-Technik bei der Knie-TEP-Implantation.

OBJECTIVE: Surgical technique in total knee arthroplasty (TKA) to combine the femur first and tibia first techniques in order to reduce surgical mistakes regarding rotation and alignment. INDICATIONS: Symptomatic arthritis of the knee. CONTRAINDICATIONS: General contraindications for TKA. SURGICAL TECHNIQUE: Osseous preparation starting with a distal femur cut. Then the proximal tibia cut is accomplished and the knee is balanced in extension after checking for correct alignment. Bone-referenced positioning of the femoral cutting block for further preparation of the femur. Finally, the rotation of the femur is checked in 90° of flexion by means of ligament tension. If required, the rotation is checked and the flexion gap balanced, respectively. POSTOPERATIVE MANAGEMENT: Mobilization with weight bearing and range of motion as tolerated. RESULTS: In a prospective study, 267 knees (160 women, 107 men, average age of 69.3 [46-89] years) were followed up preoperatively and after 6 weeks. The clinical results were based on the American Knee Society score. The scores were 48.9 (32-68) preoperatively and 86.5 (75-100) at follow-up. Radiologically 92.1% of the knees showed a malposition <3°.

The role of the transverse acetabular ligament for acetabular component orientation in total hip replacement: an analysis of acetabular component position and range of movement using navigation software.

Orientation of the native acetabular plane as defined by the transverse acetabular ligament (TAL) and the posterior labrum was measured intra-operatively using computer-assisted navigation in 39 hips. In order to assess the influence of alignment on impingement, the range of movement was calculated for that defined by the TAL and the posterior labrum and compared with a standard acetabular component position (abduction 45°/anteversion 15°). With respect to the registration of the plane defined by the TAL and the posterior labrum, there was moderate interobserver agreement (r = 0.64, p < 0.001) and intra-observer reproducibility (r = 0.73, p < 0.001). The mean acetabular component orientation achieved was abduction of 41° (32° to 51°) and anteversion of 18° (-1° to 36°). With respect to the Lewinnek safe zone (abduction 40° ±10°, anteversion 15° ±10°), 35 of the 39 acetabular components were within this zone. However, there was no improvement in the range of movement (p = 0.94) and no significant difference in impingement (p = 0.085). Alignment of the acetabular component with the TAL and the posterior labrum might reduce the variability of acetabular component placement in total hip replacement. However, there is only a moderate interobserver agreement and intra-observer reliability in the alignment of the acetabular component using the TAL and the posterior labrum. No reduction in impingement was found when the acetabular component was aligned with the TAL and the posterior labrum, compared with a standard acetabular component position.

[TKA revision of semiconstraint components using the 3-step technique]. / Knie-TEP-Revision auf ein halbgekoppeltes Prothesensystem mit der 3-Schritt-Technik.

OBJECTIVE: The surgical goal is to achieve a pain free and stable knee joint after revision total knee arthroplasty in three steps. An important component of the technique is the reproducible restoration of the joint line. INDICATIONS: Revision total knee arthroplasty. CONTRAINDICATIONS: Complete bone loss at the knee joint (epicondyles and tibia plateau), persistent joint infection, loss of the extension apparatus, and neurological disease with progressive ligament instability. SURGICAL TECHNIQUE: Implantation of revision components is performed in three steps. The first step is the positioning of the tibia component at the correct height and rotation. As the position of the tibial articular surface is independent of the knee position, the tibia serves as a reference both in extension and in flexion. The second step consists of balancing the knee joint in flexion and, thereby, definition of the flexion gap and the rotation of the femoral component. In the third step, the reconstruction and balancing of the knee joint in extension is performed. POSTOPERATIVE MANAGEMENT: Mobilization with weight bearing and range of motion as tolerated depending on osseous and soft tissue condition at surgery. The surgical technique does not influence the further treatment. RESULTS: In a prospective study, 168 consecutive knee revisions operated by the first author were examined clinically and radiologically preoperatively and at a mean follow-up of 38 months (range 22-61 months). There were 96 knees from women and 72 were from men with an average age of 74.6 years (range 51-92 years). Clinical results were based on the American Knee Society score. The score showed 47.6 (range 32-63) preoperatively and 81.5 (range 62-95) at follow-up. Radiologically, 92.7% of the knees showed a malposition <3°. The joint line was correctly reconstructed in 86.3% based on the preoperative plan; 89% of the patella showed correct tracking in the patella tangential view.

[Toxicity of antiseptics on chondrocytes in vitro]. / Toxizität lokaler Antiseptika auf Chondrozyten in vitro.

AIM: Local antiseptics are commonly used for perioperative skin and wound disinfection and as solutions for joint lavage. Therefore, we examined if an intra-articular use of these antiseptics is possible by using an IN VITRO chondrocyte model. MATERIAL AND METHODS: Articular chondrocytes harvested from 7 patients were cultured. After reaching 80% confluency different concentrations (0%, 1%, 10%, 50%, 100%) of polyhexanide, hydrogen peroxide and povidone-iodine were added for 5 minutes. Afterwards, the solution was removed and the chondrocytes were cultured for 24 hours. Subsequently the vitality and proliferation rate (DNA synthesis) were analysed with the WST-1 and BrdU tests. RESULTS: 1% povidone-iodine and 1% hydrogen peroxide solutions significantly (p=0.001) decreased the chondrocyte vitality as compared to our control group. There was no significant difference (p=0.71) after the application of 1% polyhexanide in the vitality ratios. A significant decrease in vitality was also observed after the application of 10% polyhexanide solution (p=0.001). Application of 1% povidone-iodine solution, 1% hydrogen peroxide solution and 10% polyhexanide revealed a decrease in the metabolic cell activity of 80% compared to our control group, whereas the activity was 65% (p=0.026) compared to the control group after application of 1% polyhexanide solution. CONCLUSION: Our results demonstrate the chondrotoxic effect of the tested antiseptic solutions in clinical used concentrations within short time points. Polyhexanide in a low concentrated solution (1%) was the antiseptic with the lowest influence on the vitality and the DNA synthesis of chondrocytes. Thus, this antiseptic solution seemed to be the best choice for intra-articular application. But overall, our study showed general limitations for the intra-articular use of local antiseptics.

Precision of computer-assisted core decompression drilling of the femoral head.

INTRODUCTION: Osteonecrosis of the femoral head is a local destructive disease with progression into devastating stages. Left untreated it mostly leads to severe secondary osteoarthrosis and early endoprosthetic joint replacement. Core decompression by exact drilling into the ischemic areas can be performed in early stages according to Ficat or ARCO. Computer-aided surgery might enhance the precision of the drilling and lower the radiation exposure time of both staff and patients. The aim of this study was to evaluate the precision of the fluoroscopically based VectorVision navigation system in an in vitro model. MATERIALS AND METHODS: Thirty sawbones were prepared with a defect filled up with a radiopaque gypsum sphere mimicking the osteonecrosis. Twenty sawbones were drilled by guidance of an intraoperative navigation system VectorVision (BrainLAB, Munich, Germany) and 10 sawbones by fluoroscopic control only. RESULTS: No gypsum sphere was missed. There was a statistically significant difference regarding the three-dimensional deviation (Euclidian norm) as well as maximum deviation in x-, y- or z-direction (maximum norm) to the desired mid-point of the lesion, with a mean of 0.51 and 0.4 mm in the navigated group and 1.1 and 0.88 mm in the control group, respectively. Furthermore, significant difference was found in the number of drilling corrections as well as the radiation time needed: no second drilling or correction of drilling direction was necessary in the navigated group compared to 1.4 in the control group. The radiation time needed was less than 1 s compared to 3.1 s, respectively. CONCLUSION: The fluoroscopy-based VectorVision navigation system shows a high feasibility of computer-guided drilling with a clear reduction of radiation exposure time and can therefore be integrated into clinical routine. The additional time needed is acceptable regarding the simultaneous reduction of radiation time.

Precision of computer-assisted core decompression drilling of the knee.

INTRODUCTION: Core decompression by exact drilling into the ischemic areas is the treatment of choice in early stages of osteonecrosis of the femoral condyle. Computer-aided surgery might enhance the precision of the drilling and lower the radiation exposure time of both staff and patients. The aim of this study was to evaluate the precision of the fluoroscopically based VectorVision-navigation system in an in vitro model. MATERIALS AND METHODS: Thirty sawbones were prepared with a defect filled up with a radiopaque gypsum sphere mimicking the osteonecrosis. 20 sawbones were drilled by guidance of an intraoperative navigation system VectorVision (BrainLAB, Munich, Germany). Ten sawbones were drilled by fluoroscopic control only. RESULTS: A statistically significant difference with a mean distance of 0.58 mm in the navigated group and 0.98 mm in the control group regarding the distance to the desired mid-point of the lesion could be stated. Significant difference was further found in the number of drilling corrections as well as radiation time needed. CONCLUSION: The fluoroscopic-based VectorVision-navigation system shows a high feasibility and precision of computer-guided drilling with simultaneously reduction of radiation time and therefore could be integrated into clinical routine.

[Postoperative autologous retransfusion of collected shed blood after total knee arthroplasty with the cell saver]. / Postoperative Drainageblutretransfusion mit dem Cellsaver bei endoprothetischem Kniegelenkersatz.

AIM: The purpose of this study was to examine if it is possible to reduce transfusion of blood units by collecting shed blood with the Cell Saver for autologous retransfusion in total knee arthroplasty (TKA). METHOD: In 186 patients drainage blood was collected over a 6-h period after total knee arthroplasty with a Cell Saver system in order to make retransfusions if necessary. A tourniquet was used routinely throughout the operation. No preoperative blood donation was performed. In 19 patients preoperative haemoglobin levels were below 12 g/dL (group A, anaemic patients). In the other 167 patients (group B) the preoperative haemoglobin levels were higher. RESULTS: 4 patients (21 %) in group A received a homologous blood transfusion. Only 1 patient (0.6 %) in group B received one unit of erythrocyte concentrate (difference statistically significant, P < 0.001). In group A 8 patients (42 %) received 284 ml (145-621 ml) Cell-Saver concentrate on average, 38 patients (23 %) in group B received 358 mL (147-776 ml) Cell-Saver concentrate on average. CONCLUSION: With a risk lower than 1 % for patients without anaemia to get a homologous blood transfusion one can do without the more expensive preoperative blood donation in total knee arthroplasty if a tourniquet is used for the operation and a Cell Saver is used for facultative retransfusion of drainage blood.

Imageless navigation for insertion of the acetabular component in total hip arthroplasty: is it as accurate as CT-based navigation?

In a prospective randomised clinical study acetabular components were implanted either freehand (n = 30) or using CT-based (n = 30) or imageless navigation (n = 30). The position of the component was determined post-operatively on CT scans of the pelvis. Following conventional freehand placement of the acetabular component, only 14 of the 30 were within the safe zone as defined by Lewinnek et al (40 degrees inclination sd 10 degrees ; 15 degrees anteversion sd 10 degrees ). After computer-assisted navigation 25 of 30 acetabular components (CT-based) and 28 of 30 components (imageless) were positioned within this limit (overall p < 0.001). No significant differences were observed between CT-based and imageless navigation (p = 0.23); both showed a significant reduction in variation of the position of the acetabular component compared with conventional freehand arthroplasty (p < 0.001). The duration of the operation was increased by eight minutes with imageless and by 17 minutes with CT-based navigation. Imageless navigation proved as reliable as that using CT in positioning the acetabular component.

[Changes in muscle torque in patients after total knee arthroplasty]. / Veränderungen der muskulären Leistungsfähigkeit bei Trägern von Kniegelenkstotalendoprothesen.

AIM: The purpose of this study was to compare muscle torque during isokinetic knee movements of patients after total knee arthroplasty (TKA) with a similar healthy group. METHOD: 43 patients were examined 3 years after primary total knee arthroplasty with an isokinetic dynamometer (Cybex 340). Torque measurements were evaluated for extension and flexion with 4 different velocities. The results were compared with a group of 43 people without knee disease. Bouth groups consist of 29 women and 14 men. The mean age was also comparable (66.4 vs. 65.8 years). RESULTS: A mean peak torque of 65.9 Nm was measured during extension with low velocity (60 degrees /s) in the group of patients with TKA -- 84.3 % of the control group (p = 0.079). At the highest velocity the patients produced 30.2 Nm. This was 72.8 % of the control group (difference statistically significant, p = 0.006). No differences were found in the Extension/Flexion ratio between the two groups. CONCLUSION: The deficites of knee strength in patients after TKA are more distinct in high velocities of motion.

Greater accuracy in positioning of the acetabular cup by using an image-free navigation system.

In a prospective and randomised clinical study, acetabular cups were implanted free-hand (control group n=22) or with computer assistance using an image-free navigation system (study group n=23). The cup position was determined postoperatively on pelvic CT. An average inclination of 42.3 degrees (range: 30 degrees -53 degrees ; SD+/-7.0 degrees ) and an average anteversion of 24.0 degrees (range: -3 degrees to 51 degrees ; SD+/-15.0 degrees ) were found in the control group, and an average inclination of 45.0 degrees (range: 40 degrees -50 degrees ; SD+/-2.8 degrees ) and an average anteversion of 14.4 degrees (range: 5 degrees -25 degrees ; SS+/-5.0 degrees ) in the computer-assisted study group. The deviations from the desired cup position (45 degrees inclination, 15 degrees anteversion) were significantly lower in the computer-assisted study group (p<0.001 each). While only 11/22 of the cups in the control group were within the Lewinnek safe zone, 21/23 of the cups in the study group were placed in this target region (p=0.003).

Adenocarcinoma of the rectum in childhood following chemotherapy and radiotherapy for a rhabdomyosarcoma--a case report.

We report a case of rectal adenocarcinoma in a 9-year-old boy, which took the form of a second malignant neoplasm following treatment for an early childhood malignancy. The abdominal complaints were for a long time interpreted as an infectious disease. At the time of diagnosis of the rectal carcinoma, the tumor had already progressed to the stage of metastatic disease. Therapy consisted of deep anterior rectal resection and regional arterial chemotherapy for liver metastases. The child died 18 months after the diagnosis of rectal carcinoma. As survival for childhood tumors improves, rare second malignant neoplasms will become increasingly common in children and adolescents. This phenomenon emphasizes the need for continued clinical surveillance of patients who have been treated with chemotherapy or irradiation for childhood tumors. The increased risk of second malignant neoplasms and an early onset of adult-type tumors has to be considered.

Particles of all sizes provoke inflammatory responses in vivo.

The aim of this study was to investigate whether all sizes of wear particles are capable of provoking inflammatory responses and whether there are different responses among different particle sizes. The knees of 40 female Balb/c mice were injected with polystyrene particles of three different diameters, 0.5 microm, 2.0 microm, and 75 microm, using a 0.1% vol/vol concentration. Seven days after particle injection, assessment of the synovial microcirculation using intravital microscopy, and histologic examination, were done. All the mice injected with polystyrene particles had enhanced leukocyte-endothelial cell interactions and histologic scores regardless of particle size when compared with control animals injected with sterile phosphate buffered saline. Polystyrene particles 0.5 microm in size provoked stronger membrane thickening and increased leukocyte-endothelial cell interactions than 75-microm particles. The fraction of rolling leukocytes was enhanced in the 2.0-microm particle group when compared with the 75-microm particle group. These results indicate that polystyrene particles of all sizes (0.5 microm, 2.0 microm, and 75 microm) are capable of inducing an inflammatory response. Small particles (0.5 microm, 2.0 microm) seem to provoke a stronger inflammatory response than larger particles (75 microm) in conditions with equal particle volume.

[Acute tissue toxicity of PMMA bone cements]. / Akute Gewebetoxizität von PMMA-Knochenzementen.

AIM: Local toxic reactions are one possible reason for fibrous tissue formation at the interface between bone and PMMA bone cement. Most of the numerous in vitro studies have shown severe cytotoxicity of bone cements and their components. However, in vivo investigations of the local tissue toxicity of bone cements have so far seldom been performed. METHODS: The in-vivo hens-egg chorion-allantoic-membrane test (HET-CAM), a well established replacement procedure for experiments with higher vertebrates, is used for the testing of potentially toxic solid and fluid substances. It was performed with PMMA bone cements, their components and their monomer extracts to measure in vivo biocompatibility. RESULTS: We showed that local toxic tissue reactions occurred, especially at the beginning of the processing phase of PMMA bone cements. We also proved that certain components of PMMA bone cements have poor tissue compatibility and sometimes cause severe local tissue changes. CONCLUSIONS: In the development of PMMA bone cements and when drafting the recommendations for their use, attention should be paid to their biocompatibility as well as their mechanical properties.

[Accuracy of an image-free cup navigation system--an anatomical study]. / Genauigkeit eines bildfreien Navigationssystemes für die Hüftpfannenimplantation--eine anatomische Studie.

The position of the acetabular cup is of decisive importance for the function of a total hip replacement (THR). Using the conventional surgical technique, correct placement of the cup often fails due to a lack of information about pelvic tilt. With CT-based and fluoroscopically-assisted navigation procedures the accuracy of implantation has been significantly improved. However, additional radiation exposure, high cost and the increased time requirement have hampered the acceptance of these techniques. The present anatomical study evaluates the accuracy of an alternative procedure--image-free navigation. This method requires little extra effort, does not substantially delay surgery, and needs no additional imaging. Press-fit cups were implanted in 10 human cadaveric hips with the help of the image-free navigation system, and the position of the cups was checked intraoperatively with a CT-based navigation system and postoperatively by computed tomography. All cups were implanted within the targeted safe zone with an average inclination of 44 degrees (range 40 degrees-48 degrees, SABW 2.7 degrees) and an average anteversion of 18 degrees (range 12-24 degrees, SABW 4.1 degrees). Analysis of accuracy of the image-free navigation software revealed only a small, clinically tolerable deviation in cup anteversion and cup inclination in comparison with the CT-based navigation system and the post operative CT scans. The evaluated image-free navigation system appears to be a practicable and reliable alternative to the computer-assisted implantation of acetabular cups in total hip arthroplasty.

[Plantar fibromatosis: therapy by total plantarfasciectomy]. / Plantarfibromatose: Therapie mit totaler Plantarfasziektomie.

Morbus Ledderhose is a rare fibromatous disease of the plantar fascia. Clinical features include palpable solitary or multiple nodules and cords, mainly affecting the medial part of the plantar fascia. When clinical symptoms occur, conservative options include stretching, orthotics, nonsteroidal antirheumatic drugs, local cortisone-injections and physiotherapy. Operative treatment is indicated in case of persistent pain or if conservative measures fail. The standard procedure includes a partial fasciectomy of the plantar aponeurosis. There is a high recurrence rate with an increased risk of complications and more aggressive ingrowth into anatomical structures after partial resection. Therefore we recommend a complete fasciectomy not only in recurrent disease, but also as the primary procedure of choice.

Tunnel enlargement and changes in synovial fluid cytokine profile following anterior cruciate ligament reconstruction with patellar tendon and hamstring tendon autografts.

There is growing evidence that cytokines such as tumor necrosis factor (TNF) alpha, interleukin (IL) 1beta, IL-6, bone morphogenetic proteins (BMP), and nitric oxide (NO) play an important role in the pathogenesis of bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction. Furthermore, the release of these mediators has been considered a possible reason for the higher incidence of bone tunnel enlargement following hamstring tendon (HST) than following patellar tendon (PT) ACL reconstruction observed in several studies. In this investigation synovial fluid samples from 13 patients were collected immediately before (24+/-7 days after ACL rupture) and 7 days after ACL surgery and values of TNF-alpha, IL-1beta, IL-6, NO, and BMP-2 were analyzed. Furthermore, the incidence of bone tunnel enlargement was assessed using radiographs 38+/-7 weeks after surgery. Six patients underwent autologous HST ACL reconstruction, and in seven patients an PT autograft was used. In the overall patient population there were significantly higher synovial fluid concentrations of IL-6 and BMP-2 postoperatively than preoperatively; TNF-alpha showed a trend towards lower postoperative levels while IL-1beta and NO remained unchanged. The concentrations of NO, TNF-alpha, and IL-6 found in the present study were clearly higher than normal values given in the literature. Assessment of bone tunnel enlargement revealed an average increase in tibial tunnel width of 28.4+/-3.1% with comparable values for HST and PT ACL reconstructions. There was no significant correlation between bone tunnel enlargement and postoperative synovial fluid concentrations of TNF-alpha, IL-1beta, IL-6, NO, and BMP-2. However, all patients with bone tunnel enlargement had higher postoperative concentrations of TNF-alpha, IL-6, and NO in the synovial fluid. There were no significant differences in concentrations between HST and PT groups. In conclusion, we observed an association between tibial bone tunnel enlargement and elevated synovial fluid concentrations of IL-6, TNF-alpha, and NO 7 days after ACL surgery indicating the potential involvement of these biological mediators in the pathogenesis of bone tunnel enlargement. However, there was no difference between HST and PT ACL reconstructions regarding synovial fluid contents of IL-6, TNF-alpha, IL-1beta, NO, and BMP-2, suggesting a comparable biological response between these autografts following their use in ACL reconstruction.

Prosthetic joint infections with osteomyelitis due to Candida albicans.

We report the case of a 78-year-old woman who suffered from a severe soft tissue and bone infection of her left knee 3 years after a total knee-joint replacement without loosening of her endoprosthesis. Cultures from joint aspiration and tissue specimen identified Staphylococcus aureus and Candida albicans. Direct microscopic examination of vital spongy bone and fibrous tissue revealed microabscesses and seeds of yeasts inside the fatty marrow and interface. After removal of the prosthesis several soft tissue and bone specimens were taken during planned re-operations. The histological examination showed no morphological changing, no reduction or extinction of the yeast cells under fluconazole therapy with a dosage of 6 mg kg(-1) body weight (400 mg daily). Curing of the fungal infection with eradication of the yeasts in the bony specimens was achieved with higher doses of 12 mg kg(-1) body weight (800 mg day(-1)) over a 2 month regimen in combination with repeated surgical debridements.

[CT-based and CT-free navigation in knee prosthesis implantation. Results of a prospective study]. / CT-basierte und CT-freie Navigation in der Knieendoprothetik. Ergebnisse einer prospektiven Studie.

INTRODUCTION: Accurate leg alignment is one important factor for long-term survival in total knee arthroplasty (TKA). The classical surgeon-controlled technique is associated with a deviation of the leg axis of more than 3 degrees in up to 30% of cases, regardless of the surgeon's experience. The aim of this study was to test the efficiency of a CT-based and CT-free navigation system in restoration of the leg axis. METHOD: 100 TKA (PFC-Sigma, DePuy) were implanted either using the CT-based or CT-free module of the Vector-Vision navigation System (BrainLAB). There were no significant differences between the groups in preoperative leg deformity. Accuracy of implantation was determined on postoperative long-leg coronal and lateral X-rays. RESULTS: A postoperative leg axis between 3 degrees varus and 3 degrees valgus was obtained in 46 patients (92%) in the CT-based group (A) and in 48 patients (96%) in the CT-free group (B). No significant differences were found for varus / valgus orientation (+/-3 degrees ) of the femoral (A=96%; B=94%) and tibial (A and B each 98%) components. CONCLUSION: The use of the CT-based and CT-free Vector-Vision system allows a significant improvement in the accuracy of implantation in TKA. The CT-based module has the advantage of precise preoperative planning. On the other hand there are additional costs and time-consuming logistics. The advantages of the CT-free module are the intraoperative visualisation of the leg axis, the ligament balancing and joint kinematics. Cutting errors can be detected and corrected with both modules.

[Tissue toxicity of local anesthetics. An in vivo trial]. / Gewebetoxizität lokaler Anästhetika im HET-CAM-Test. Ein In-vivo-Experiment.

AIM: Local anesthetics are often administered intra-articularly after knee surgery. The aim of this study was to determine differences in irritancy of local anesthetics in an in vivo test performed on the chorioallantoic membrane of hen's eggs (HET-CAM test) to evaluate the specific irritation score. METHOD: After incubation for 9 days, the chorioallantoic membrane was prepared and then exposed to different local anesthetics (Naropin, Scandicain,Carbostesin,Xyloneural). RESULTS: We found no irritating values for the tested substances. No vascular injuries of the chorioallantoic membrane could be detected. Therefore, the irritation score was measured according to the standard protocol with an irritation score=0. CONCLUSION: Our results show that local anesthetics often used in clinics do not provoke severe vascular injuries as a sign of tissue toxicity. Therefore, the customary concentrations can be recommended for clinical use.