Biomechanical analysis of polyaxial locking vs. non-locking plate fixation of unstable fractures of the distal fibula: A cadaver study with a bone only model.

BACKGROUND: Open reduction and internal fixation is the current standard of treatment of displaced distal fibula fractures, whereupon using a lag screw often is impossible because of a multifragmantary fracturezone. This study investigates in what extend polyaxial-locking plating is superior to non-locking constructs in unstable distal fibula fractures. METHODS: Seven pairs of human cadaver fibulae were double osteotomized in standardized fashion with a 5mm gap. This gap simulated an area of comminution, where both main fragments were no longer in direct contact. One fibula of the pair was managed using a 3.5-mm screw in a polyaxial-locking construct and the other fibula in a non-locking construct.

[Injuries of the peroneal tendons : Often overlooked]. / Verletzungen der Peronealsehnen : Häufig übersehen.

CLINICAL ISSUE: Injuries of the peroneal tendons are rare and often overlooked. Typical pathologies are tendinitis, tears and dislocation. Accompanying injuries are fractures. They are often associated with instability in the ankle and rearfoot deformities; therefore, these pathologies should be excluded or taken into consideration in the treatment. The clinical examination is crucial for the diagnosis. DIAGNOSTIC WORK-UP: Ultrasound and magnetic resonance imaging (MRI) examinations are very helpful; however, the true extent of the tendon pathology is often first seen during surgery. Bony injuries and deformities are assessed radiographically and by computed tomography (CT). PERFORMANCE: Although conservative treatment is generally used at the beginning of therapy, progression is more likely to occur in the case of tears; therefore, the correct timing for an operative therapy should not be missed. Dislocations are the domain of operative therapy. Acute tendinitis, on the other hand, is usually accessible to conservative therapy if it is not the result of a gross deformity. ACHIEVEMENTS: Rehabilitation after operative treatment is demanding and prolonged especially after operative therapy of peroneal tendon tears. The results to be expected appear promising.

Gentamicin coating of plasma chemical oxidized titanium alloy prevents implant-related osteomyelitis in rats.

Implant related infection is one of the most feared and devastating complication associated with the use of orthopaedic implant devices. Development of anti-infective surfaces is the main strategy to prevent implant contamination, biofilm formation and implant related osteomyelitis. A second concern in orthopaedics is insufficient osseointegration of uncemented implant devices. Recently, we reported on a macroporous titanium-oxide surface (bioactive TiOB) which increases osseointegration and implant fixation. To combine enhanced osseointegration and antibacterial function, the TiOB surfaces were, in addition, modified with a gentamicin coating. A rat osteomyelitis model with bilateral placement of titanium alloy implants was employed to analyse the prophylactic effect of gentamicin-sodiumdodecylsulfate (SDS) and gentamicin-tannic acid coatings in vivo. 20 rats were randomly assigned to four groups: (A) titanium alloy; PBS inoculum (negative control), (B) titanium alloy, Staphylococcus aureus inoculum (positive control), (C) bioactive TiOB with gentamicin-SDS and (D) bioactive TiOB plus gentamicin-tannic acid coating. Contamination of implants, bacterial load of bone powder and radiographic as well as histological signs of implant-related osteomyelitis were evaluated after four weeks. Gentamicin-SDS coating prevented implant contamination in 10 of 10 tibiae and gentamicin-tannic acid coating in 9 of 10 tibiae (infection prophylaxis rate 100% and 90% of cases, respectively). In Group (D) one implant showed colonisation of bacteria (swab of entry point and roll-out test positive for S. aureus). The interobserver reliability showed no difference in the histologic and radiographic osteomyelitis scores. In both gentamicin coated groups, a significant reduction of the histological osteomyelitis score (geometric mean values: C = 0.111 ± 0.023; D = 0.056 ± 0.006) compared to the positive control group (B: 0.244 ± 0.015; p < 0.05) was observed. The radiographic osteomyelitis scores confirmed these histological findings.

Does a polyaxial-locking system confer benefits for osteosynthesis of the distal fibula: A cadaver study.

BACKGROUND: In plate osteosynthesis involving the distal fibula, antiglide plating is superior to lateral plating in terms of the biomechanical properties. The goal of this study was to examine whether polyaxial-locking implants confer additional benefits in terms of biomechanical stability. METHODS: Seven pairs of human cadaveric fibulae were subjected to osteotomy in a standardized manner to simulate an uncomplicated Weber B fracture. The generated fractures were managed with a dorsolateral antiglide plate. To this end, one fibula of the pair was subjected to non-locking plating and the other to polyaxial-locking plating. Biomechanical tests included quantification of the primary bending and torsional stiffness. In addition, the number of cycles to failure in cyclic bending loading were determined and compared. Bone mineral density was measured in all specimens. RESULTS: Bone mineral density was comparable in both groups. Primary stability was higher in the polyaxial-locking group under torsional loading, and higher in the non-locking group under bending loading. The differences, however, were not statistically significant. All specimens except for one fixed-angle construct failed the cyclic loading test. The number of cycles to failure did not differ significantly between polyaxial-locking and non-locking fixation. CONCLUSION: In a cadaveric Weber B fracture model, we observed no differences in biomechanical properties between polyaxial-locking and non-locking fixation using an antiglide plate. Based on the biomechanical considerations, no recommendation can be made regarding the choice of the implant. Further biomechanical and clinical studies are required. CLINICAL RELEVANCE: Information on the behavior of polyaxial-locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.

[Plantar approach to hindfoot arthrodesis with compressed angle stable locking option]. / Plantarer Zugang zur Rückfußarthrodese mit komprimierter winkelstabiler Verriegelungsoption.

BACKGROUND: Tibiotalocalcaneal arthrodesis is indicated in severe combined arthritis of the upper and lower ankle joints and otherwise untreatable malpositioning of the hindfoot. CONCLUSION: Currently available arthrodesis nails have a hindfoot valgus bend which allows the anatomy to be more faithfully reproduced and respected. Anatomical investigations show the endangered structures during retrograde arthrodesis nailing. The valgus bend of the arthrodesis nail necessitates a corresponding correctly placed opening in the calcaneus and talus as the entry point for the nail. A locking screw in the calcaneus running from posterior to anterior increases the stability and is now taken into consideration for nearly all designs of arthrodesis medullary nails. The compression mechanism can be used for apposition and pressing the arthrodesis surfaces together and locking in the hindfoot should be carried out in an angle stable fashion. Augmentation of the locking screws in the calcaneus with bone cement can be an option as a salvage procedure in revision cases.

[Diagnosis and treatment of periprosthetic infections]. / Diagnose und Therapie periprothetischer Infektionen.

The differentiation of periprosthetic infections into early onset and late onset infections is the determining factor fores the therapeutic strategy. The diagnosis of chronic unapparent infections is sometimes difficult. The therapeutic success, especially in early onset infections, is essentially influenced by a well-timed diagnosis and an immediate therapy. Surgical wound debridement with preservation of the prosthesis, one-stage replacement and two-stage replacement all with concomitant appropriate systemically administered double combined antibiotics are therapeutic options depending on factors, such as the duration of the infection. Prosthesis replacement is currently the only option to treat biofilm colonization of endoprosthetic surfaces. The bacterial adhesion on polyethylene can be extremely resistant. Due to the therapeutic consequences, periprosthetic infections remain one of the worst complications in endoprosthetic joint replacement.

[Therapy of acute ankle sprain: one-year results of primary conservative treatment]. / Therapie der fibulotalaren Bandverletzung: Ein-Jahres-Ergebnisse nach primär konservativer Behandlung.

INTRODUCTION AND AIM: Ankle sprains (supination-eversion injury) have a high incidence. Conservative treatment is generally the method of choice. This study is intended to evaluate the 1-year results of a standardised treatment protocol. MATERIAL AND METHODS: A total of 416 patients who had suffered an ankle sprain were included into this study. All of them had undergone primary conservative treatment. A total of 66 of them (15.9 %) had undergone operative treatment within one year after injury. The indications for operation were persistent pain, swelling or persistent instability. In 33 patients an arthroscopy for evaluation of the joint and debridement was used. In the case of a persistent instability 22 ligament augmentations (Kuner periostal flap) and 11 peroneus tenodesis (Watson-Jones) were performed. The evaluation was done by using the AOFAS score ("Ankle Hindfoot Scale" of the American Orthopedic Foot and Ankle Society). RESULTS: A 1-year follow-up was possible in 96.4 % of the patients. The mean AOFAS score was 77.1 ± 10.5 points after conservative treatment. Those patients who needed an arthroscopic debridement had a slightly better outcome (AOFAS score 79.5 ± 10.2 points). Patients who had undergone stabilisation operations tended to have the best outcome (p = 0.093). The AOFAS score was 79.6 ± 15.4 points in patients after periostal flap augmentation, respectively, 83.0 ± 7.4 points after peroneus tenodesis. CONCLUSIONS: The results confirm the benefit of conservative treatment in acute ankle sprain. Even so about 15 - 20 % of the patients still suffer from persistent pain, swelling or instability. The indication for operative intervention should be made relatively broadly. Most of these patients profit from the operation. Above all, after ankle sprain patients need a continuous re-evaluation by a specialised centre during the first post-injury year.

In vitro phenotypic modulation of chondrocytes from knees of patients with osteochondritis dissecans: implications for chondrocyte implantation procedures.

We attempted to characterise the biological quality and regenerative potential of chondrocytes in osteochondritis dissecans (OCD). Dissected fragments from ten patients with OCD of the knee (mean age 27.8 years (16 to 49)) were harvested at arthroscopy. A sample of cartilage from the intercondylar notch was taken from the same joint and from the notch of ten patients with a traumatic cartilage defect (mean age 31.6 years (19 to 52)). Chondrocytes were extracted and subsequently cultured. Collagen types 1, 2, and 10 mRNA were quantified by polymerase chain reaction. Compared with the notch chondrocytes, cells from the dissecate expressed similar levels of collagen types 1 and 2 mRNA. The level of collagen type 10 message was 50 times lower after cell culture, indicating a loss of hypertrophic cells or genes. The high viability, retained capacity to differentiate and metabolic activity of the extracted cells suggests preservation of the intrinsic repair capability of these dissecates. Molecular analysis indicated a phenotypic modulation of the expanded dissecate chondrocytes towards a normal phenotype. Our findings suggest that cartilage taken from the dissecate can be reasonably used as a cell source for chondrocyte implantation procedures.

[Comparative study on the strength of different mechanisms of operation of multidirectionally angle-stable distal radius plates]. / Vergleichende Studie zur statischen Festigkeit unterschiedlicher Verblockungsmechanismen multidirektional winkelstabiler Verriegelungen distaler Radiusplatten.

INTRODUCTION: Polyaxial angle-stable plating is thought to be particularly beneficial in the management of complex intra-articular fractures of the distal radius. The present study was performed to investigate the strength of polyaxial locking interfaces of distal radius plates. MATERIAL AND METHODS: We tested the polyaxial interfaces of 3 different distal radius plates (2.4 mm Variable Angle LCP Two-Column Volar Distal Radius Plate, Synthes, Palmar Classic, Königsee Implantate and VariAx Plate Stryker). The strength of 0° and 10° screw locking angle was obtained during static loading. RESULTS: The strength of Palmar Classic with a 0° locking angle is significantly the best of all tested systems. With a 10° locking angle there is no significant difference between Palmar Classic, Two column Plate and VariAx Plate. CONCLUSION: The strength of polyaxial interfaces differs between the tested systems. A reduction of ultimate strength is due to increases of screw locking angle. The design of polyaxial locking interfaces should be investigated in human bone models.

Navigation in femoral-shaft fractures--from lab tests to clinical routine.

INTRODUCTION: This study evaluates the use of a navigation system (BrainLAB, Feldkirchen, Germany) to intra-operatively check for correct length, axis and rotation in intramedullary nailing of femoral-shaft fractures in an experimental setting and in clinical routine. MATERIALS AND METHODS: We tested the navigation system in two experimental settings before introducing it into clinical routine. In the first experiment, 10 osteotomised model femora were fixed with intramedullary nails by using a navigation system. The goal was a locking fixation in predefined values for length and rotation. In the second experiment, eight examiners assessed values for rotation and length of one femur 10 times to examine the accuracy and reproducibility of that determination. Following this, we navigated 40 femoral nailing procedures in our department. Preoperatively, we assessed values of femur geometry on the contralateral side in a computed tomography (CT) scan and reproduced these values intra-operatively on the fractured side, guided by the navigation system. During the intervention, we recorded the length of the procedure steps and the fluoroscopy time. We verified the intra-operative values achieved with the navigation system in a postoperative CT scan and documented differences in rotation and length. After the assessment, we analysed the data for different findings on femur geometry, fluoroscopy time and procedure duration. RESULTS: The experimental evaluation showed a range of ±5° for anteversion differences and ±2.3 mm for length differences. We estimated this accuracy as sufficient to use the system in clinical routine. The navigation system was used for 40 fracture fixations. All our criteria for restoring femoral geometry could be achieved by navigation guidance in these procedures. Setting up the system took on average 33±11.5 min. An additional fluoroscopy time of 36±22 s was needed to acquire the reference X-rays and to verify pin placement. The differences between anteversion values assessed in intra-operative planning steps on the navigation system and values assessed with a postoperative CT were on average 5.4±3.5°, whilst femur length differed on average by 4±4 mm. DISCUSSION: Many authors judge intra-operative control of anteversion in femoral-shaft fracture fixation as problematic. Neither our experimental navigation assessment nor our clinical navigated evaluation showed relevant anteversion differences to a postoperative CT assessment of femur geometry. After initial training, guidance by a navigation system achieves consistent results in a clinical situation. CONCLUSIONS: The use of a navigation system to align axis, length and rotation led to a secure way of avoiding any relevant malalignment in complex femur-shaft fractures whilst exposing patients to an acceptable amount of additional procedure sequences. Malalignment can be avoided by using a navigation system in the operative treatment of femoral-shaft fractures and may be integrated into clinical routine in specialised centres.

[Vacuum-assisted closure therapy for the treatment of acute postoperative osteomyelitis]. / Vakuumtherapie bei akuter postoperativer Osteitis.

AIM: Vacuum-assisted closure is used frequently for the treatment of posttraumatic osteomyelitis of the extremities. After debridement and repeated VAC dressing changes, the wounds are closed by secondary suture, split-thickness skin grafts or local flaps. However, no objective parameters describe the time point for secondary wound closure. Our thesis was that negative microbiological results from bone specimens can indicate the time for secondary wound closure. Moreover, treatment course and clinical outcome after 3.4 years should be compared to those of other surgical approaches for acute postoperative osteomyelitis from the literature. PATIENTS AND METHODS: 43 patients with acute postoperative osteomyelitis of the extremities and the pelvis were treated by serial bone and soft tissue debridements and VAC therapy and analysed prospectively. Debridements were repeated until the wounds were macroscopically free from signs of infection (good granulation/no necrosis). During each revision a bone specimen was taken for microbiological analysis. Number of revisions, bacterial cultures, type of wound closure and recurrence of infection after 3 years and 5 months on average after the last surgery was analysed. RESULTS: 9.8 debridements on average were performed until eradication of infection and secondary wound closure. Despite the absence of macroscopic infection, bacteria were still found in bone samples from 15 of 43 patients. Three biopsies were free of bacteria for the first time right before wound closure, 25 samples had become negative during the treatment. Six recurrences (19.3 %) were noted after 3.4 years on average. Four patients from the group of negative bone biopsies (19 %) and two patients from the group of persisting bacteria before secondary closure (20 %) had a recurrence of infection. CONCLUSION: In about one third of the bone biopsies bacteria persisted. This bacterial load had no correlation to wound healing and rate of recurrence after over 3 years. In conclusion, microbiological bone samples are not suitable as an indicator for the time point of secondary wound closure. Compared to other treatment options in acute postoperative osteomyelitis from the literature (especially implantation of local antibiotics), no advantage of vacuum-assisted closure could be shown concerning number of debridements and rate of recurrences.

[Vacuum-assisted closure therapy for the treatment of skin and soft-tissue infections. Are wound specimens of use in planning secondary wound closure?]. / Vakuumtherapie bei Haut- und Weichgewebsinfektionen der Extremitäten. Nutzen des Wundabstrichs bei der Planung des sekundären Wundverschlusses?

AIM: Vacuum-assisted closure is used frequently for the treatment of skin and soft-tissue infections (SSTI) of the extremities. After debridement and repeated VAC dressing changes, the wounds are closed by secondary suture, split-thickness skin grafts or local flaps. However, no objective parameters describe the time point for secondary wound closure. Our thesis was that negative microbiological results from wound specimens can indicate the time for secondary wound closure. PATIENTS AND METHODS: 24 patients with SSTI of the extremities were treated by serial debridements and VAC therapy and analysed prospectively. Debridements were repeated until the wounds were macroscopically free from signs of infection (good granulation/no necrosis). During each revision specimens were taken for microbiological analysis. Moreover, number of revisions, bacterial cultures, type of wound closure and wound status after 3 years and 5 months on average after the last surgery were analysed. RESULTS: 6.3 revisions on average were performed until secondary wound closure was possible. In spite of the absence of macroscopic infection, bacteria were still found in tissue samples from 14 of 24 wounds. 6 wounds were free of bacteria for the first time right before wound closure, 3 wounds had become negative during the treatment. After 3.4 years on average, the wounds of all 18 patients available for examination had healed well and were free from signs of infection. CONCLUSION: Vacuum-assisted closure resulted in clean, good granulating wounds without necrosis. However, in more than half of the wounds bacteria persisted. This bacterial load had no correlation to wound healing and outcome after over 3 years. In conclusion, microbiological tissue samples are not suitable as indicator for the time point of secondary wound closure in SSTI.

[The use of DensiProbe™ in hindfoot arthrodesis. Can fusion failure be predicted by mechanical bone strength determination?]. / Zur Nutzung von DensiProbe™ bei der Rückfußarthrodese. Kann das Versagen durch eine mechanische Bestimmung der Knochenfestigkeit vorhergesagt werden?

AIM: Bone quality is a main factor in implant fixation. After having shown promising results, we have further investigated the use of the DensiProbe™ as an intraoperative measurement tool for evaluation of calcaneal bone quality and prediction of nailed hindfoot arthrodesis failure. METHOD: In this add-on study 19 nail arthrodeses were performed using a conventional screw plus a locked blade (n = 6) or plus a locked screw (n = 13) in the calcaneus. A specially devised tool was inserted at the fixation sites of the screws and the cancellous break-away torque was measured. The constructs were then cyclically loaded to failure. RESULTS: We saw a wide range of BMD (1.9-185.9 mgHA/cm³, mean 102.4 mg/cm³, SD 53.5). The peak torque was 0.47-1.78 Nm (mean 0.92 Nm, SD 0.46) at the proximal screw site (PSS) and 0.24 and 1.2 Nm (mean 0.63 Nm, SD 0.37) at the distal screw site (DSS), respectively, and 0.42 and 1.52 Nm (mean 1.00 Nm, SD 0.36) in the screw plus blade group (PSS). The number of cycles correlated with peak torque (two screws group PSS: p = 0.002, r² = DSS: 0.61 p = 0.001, r² = 0.90; screw plus blade group PSS: p = 0.001, r² = 0.99). Peak torque also correlated with BMD in both groups (two screws group PSS: p = 0.01, r² = 0.71; DSS: p = 0.001; r² = 0.83; screw plus blade group PSS: 0.42 and 1.52 Nm, mean 1.00 Nm, SD 0.36). CONCLUSION: A mechanical bone measurement tool like the DensiProbe™ seems to be suitable for predicting tibiotalocalcaneal arthrodesis failure in a biomechanical test set-up. As a restriction in clinical practice failure is multifactorial and prediction cannot be based upon these measurements only.

[Sustentaculum tali screw placement for calcaneus fractures--different navigation procedures compared to the conventional technique]. / Sustentaculum-tali-Schraubenplatzierung bei der Versorgung von Kalkaneusfrakturen--verschiedene Navigationsverfahren im Vergleich zur konventionellen Technik.

AIM: Precise placement of the sustentaculum tali screw is essential for fixation of calcaneus fractures to achieve the best fixation strength. In the clinical practice, this procedure is demanding due to the complex anatomic configuration of the calcaneus and the limited visualisation in the intraoperative fluoroscopic images. The aim of this study was an evaluation of the accuracy for the sustentaculum tali screw placement by using different navigation procedures compared to the standard procedure. The different navigation specific workflows were evaluated and the feasibility of each procedure proven in clinical applications. METHOD: Eight sustentaculum screws per group were placed in an artifical Synbone model. Different navigation procedures were evaluated: 2D-fluoroscopy (group I), 3D-fluoroscopy (group II), fluoro-free (group III) and compared to the conventional screw placement without navigation (group IV). For each screw the time of fluoroscopy and the duration of the procedure were measured. The accuracy was evaluated postoperatively by computed tomography using axial slices and coronary as well as sagittal reformations. Furthermore, the workflow of each navigation procedure was analysed and proven in clinical applications. RESULTS: In the experimental setup, no radiation exposure was mandatory for the conventional and fluoro-free procedures, whereas mean fluoroscopy times of 17 +/- 1.03 und 66.8 +/- 0.9 were measured for 2D- and 3D-navigation procedures. In line with this, the overall mean procedure times for the screw placement were 1.26 +/- 0.05 (group IV), 3.49 +/- 0.26 (group III), 13.32 +/- 0.49 (group I) und 19.04 +/- 1.41 minutes (group II). No significant differences were observed for the accuracy of screw placement. In the clinical practice a better orientation was achieved by use of a navigation system. The fluoro-free procedure can be easily integrated into the common operation workflow, whereas the workflow of both image-based navigation procedures is technically demanding. CONCLUSION: Navigation procedures seem to be helpful for the precise placement of sustentaculum tali screws in cases of operative calcaneus fracture fixation. The kind of application to be used depends on the infrastructure of the department and the navigation-experience of the operating room team. Whereas the fluoro-free procedure is intuitive in use, the 2D-navigation does not justify the extra efforts. The 3D-procedure is the recommended application for surgeons familiar with navigation, providing the best orientation due to the slice image visualisation in all three dimensions.

[Necrotizing fasciitis after "banal" back pain. An unusual course of a retrocoecal appendicitis and its sequellae]. / "Banale" Rückenschmerzen als erstes Symptom einer nekrotisierenden Fasziitis : Ungewöhnlich verlaufende retrozökale Appendizitis und ihre Folgen.

Necrotizing fasciitis is a life-threatening disease which can only be successfully treated by an interdisciplinary team. An immediate and radical debridement with opening of all compartments and debridement of the affected fascia is the basis for a successful therapy. We report about the treatment of a 21-year-old man who was taken to hospital due to "banal" back pain which was caused by a perforated appendicitis. In only 2 days necrotizing fasciitis developed which spread out over the complete right leg.

[Tibiotalocalcaneal arthrodesis using a compressive retrograde locking nail with hindfoot valgus]. / Die tibiotalokalkaneare Arthrodese mit einem winkelstabilen Marknagel mit Rückfussvalgus und Kompressionsmöglichkeit.

AIM: The purpose of this study was to evaluate the first clinical experiences with the newest generation retrograde arthrodesis nail. METHODS: 28 patients who had tibiotalocalcaneal arthrodesis between 2005 and 2007 using a retrograde compression nail fixation (T2 AAN, Stryker, Duisburg, Germany) were retrospectively reviewed. Complications, functional outcome scores, and patient satisfaction were determined and the radiographs were evaluated for bony healing. RESULTS: The mean time interval until follow-up was 16 months (range: 7-27). All but 1 ankle showed a radiographically healed arthrodesis. 25 patients (89 %) were satisfied with the outcome. The average functional scores at follow-up were 64 (38-86 points) points for the American Orthopedics Foot and Ankle Score (AOFAS) and 65 points for the Mazur Ankle Scoring System (30-83 points). We recorded complications in 7 patients (25 %) including 1 deep infection with breakage of the calcaneus screw, 3 reinfections, 1 deep vein thrombosis, 1 intraoperative fracture of the tibia, 1 delayed union and 1 non-union. CONCLUSION: Tibiotalocalcaneal arthrodesis is a salvage procedure. Using a specifically designed retrograde intramedullary nail is a reliable method to achieve fusion. Patient satisfaction is high, but the procedure is demanding and complications are frequent. After infections the indication for nail arthrodesis should be evaluated carefully in each case.

[Navigation-assisted nailing of femoral shaft fractures--experimental and clinical results]. / Navigationsgestützte Marknagelung von Femurschaftfrakturen - experimentelle und klinische Ergebnisse.

AIM: The aim of the study was to evaluate the application of a navigation system (Brainlab) to control length and torsion intraoperatively while nailing a femoral shaft fracture. METHOD: At first the system was tested with 10 fractured synthetic bones. The postoperatively reached length and torsion were measured and the difference to the envisioned values statistically evaluated. Clinically we used the navigation system for patients with complex femoral shaft fractures. We always performed a preoperative computed tomography of the opposite leg to analyse the axis and fixed the fractured leg on these parameters using the navigation system. We noticed as improvement opportunities, the duration of the operative steps and the radiation exposure. The operative result was radiologically controlled and the torsion and length differences to the intraoperative measurement evaluated. Furthermore, we analysed the duration of the operation steps including the additional radiation exposure. RESULTS: There were no technical problems during operations on the synthetic bones. The accuracy was with +/- 5 degrees or +/- 2 mm good enough to use the already approved system clinically. The navigation system was used for 17 operations. All navigation-assisted operations were completed successfully. It took an average time of 32 min to install the navigation system and required an additional X-ray time of 44 sec. The average postoperative rotational deviation was 5.5 degrees . The average difference in length was 2 mm. CONCLUSION: The application of a navigation system for repositioning of femoral shaft axes and controlling the length and torsion while nailing complex femoral shaft fractures is associated with some additional work. Nevertheless, in our study a relevant rotational deviation can be avoided by using the navigation system. To prove the advantage of the navigation system over the conventional technique, clinical studies with larger number of cases are necessary.

[2D-fluoroscopic navigated screw osteosynthesis of acetabular fractures: A preliminary report]. / 2D-fluoroskopisch navigierte perkutane Schraubenosteosynthese von Azetabulumfrakturen: Erste Ergebnisse einer neuen Methode.

INTRODUCTION: The current gold standard for operatively treated acetabular fractures is open reduction and internal fixation. In this study we report the early results of percutaneous screw osteosynthesis of acetabular fractures in 14 cases, using a computer navigation system to reduce screw misplacement, approach associated risks and radiation exposure. RESULTS: All 36 acetabular screws were placed correctly without any perioperative complication. The mean operation time per screw was 54 min, the mean fluoroscopic time per screw was 87 s. In the follow-up examinations (current rate: 71 %, mean follow-up: 13.1 +/- 1.8 months) no fixation failure or development of post-traumatic osteoarthritis was seen. One wound infection occured. CONCLUSION: Our first experience with this novel approach is promising and serious advances of fluoroscopic navigated percutaneous screw osteosynthesis of well selected acetabular fractures can be expected.

[Preservation of hip prosthesis with local surgical revision and creation of a fistula persistens : an option for palliative treatment of periprosthetic infection in old, polymorbid patients?]. / Hüftprothesenerhalt mit lokaler chirurgischer Revision und Anlage einer Fistula persistens : Ausnahmeoption zur palliativen Therapie des periprothetischen Infekts bei alten polymorbiden Patienten?

BACKGROUND: The number of implanted hip prostheses is increasing constantly. At the same time the patients are becoming older and older. Thus, also patients with periprosthetic infections are older and therefore sicker. Uniform guidelines for the treatment of infected arthroplasties are controversial. Empirical studies show that the explantation of the original prosthesis and implantation of a revision may be the option with the greatest chance of success. These very aggressive procedures may overburden the old, polymorbid patient. The aim of this study was to ascertain whether or not keeping the hip prosthesis in combination with local debridement, formation of a permanent fistula and long-term administration of antibiotics is a possible option for the treatment of infected hip prostheses in old and polymorbid patients. PATIENTS: Between 01.01.2004 and 28.01.2007, 12 patients with periprosthetic infection after hip arthroplasty (PIH) were treated. Their average age was 79.8 years. Eleven patients were rated ASA III preoperatively. The prostheses were on average 23.8 weeks old when the first signs of infection occurred. In 10 cases the infection was caused by Staphylococcus (MRSA 3x). The main comorbidities were hypertension, diabetes, coronary heart disease and thyroid malfunction. RESULTS: After a mean 8.83 months, six patients were deceased (average age 85.50 years). In five of the remaining six patients the fistula worked without any problem. In one case the fistula was occluded. None of the patients showed any sign of acute infection. All were able to walk with full weight-bearing on the affected hip. CONCLUSION: Restricting the indication to old, polymorbid patients, preservation of the arthroplasty in combination with local surgical debridement, permanent fistula and long-term systemic administration of antibiotics seems to be an alternative to explantation of the prosthesis with consecutive revision arthroplasty or resection arthroplasty.