[Intraoperative virtual implant planning for volar plate osteosynthesis of distal radius fractures]. / Intraoperative virtuelle Implantatplanung bei der volaren Plattenosteosynthese distaler Radiusfrakturen.

BACKGROUND: Digital planning of implants is in most cases conducted prior to surgery. The virtual implant planning system (VIPS) is an application developed for mobile C-arms, which assists the virtual planning of screws close to the joint line during surgery for treatment of distal radius fractures with volar plate osteosynthesis. The aim of this prospective randomized study was to acquire initial clinical experiences and to compare the VIPS method with the conventional technique. METHOD: The study included 10 patients for primary testing and 30 patients with distal radius fractures of types A3, C1 and C2, divided in 2 groups. In the VIPS group, after placement of the plate and fracture reduction, a virtual 3D model of the plate was matched with the image of the plate from the fluoroscopic acquisition. Next, the length and position of the screws close to the joint line were planned on the virtual plate. The control group was treated with the same implant in the conventional way. Data were collected regarding screw replacement, fluoroscopy and operating room (OR) times. RESULTS: The VIPS group included six A3, one C1 and eight C2 fractures, while the control group consisted of six A3 and nine C2 fractures. Three screws were replaced in the VIPS group and two in the control group (p = 0.24). The mean intraoperative fluoroscopy time of the VIPS group amounted to 2.58 ± 1.38 min, whereas it was 2.12 ± 0.73 min in the control group (p = 0.26). The mean OR time in the VIPS group was 53.3 ± 34.5 minutes and 42.3 ± 8.8 min (p = 0.23) in the control group. CONCLUSION: The VIPS enables a precise positioning of screws close to joint line in the treatment of distal radius fractures; however, for routine use, further development of the system is necessary.

[Intraoperative 3-dimensional imaging - beneficial or necessary?]. / Intraoperative dreidimensionale Bildgebung - nützlich oder notwendig?

BACKGROUND: With reference to two large retrospective studies we would like to make a contribution to the discussion whether intraoperative 3-dimensional imaging is only a helpful tool or state of the art for some special indications. METHODS: To answer this question the intraoperative revision rates of syndesmotic injuries and calcaneal fractures were analyzed over a period of 10 years and 8 years, respectively. Additionally, the clinical outcome was evaluated depending on the restoration of the joint reconstruction. RESULTS: Intraoperative revision rates of 32.7 % of 251 syndesmotic injuries and 40.3 % of 377 calcaneal fractures were found. The mutivariate analysis showed that residual joint incongruity leads to significantly worse clinical and radiological outcome of calcaneal fractures. CONCLUSIONS: Correct assessment of alignment and joint line reconstruction are not possible by means of fluoroscopy in every case of syndesmotic injuries and calcaneal fractures. Therefore, intraoperative 3-dimensional imaging should be used in the treatment of these injuries due to the high intraoperative revision rates and the clinical relevance.

[Intraoperative 3D C-arm imaging. State of the art]. / Die intraoperative 3D-C-Bogen-Anwendung : State of the art.

Mobile C-arms with the option of 3D imaging like the Iso-C(3D) allow for intraoperative 3D visualization of anatomical areas with complex three-dimensional structures like articular surfaces. In an 8-year period we performed 1,841 intraoperative control scans following osteosynthesis. Among these patients we registered the number of intraoperative adjustments of fracture reduction and implant position in correlation to the area of surgery. The majority of intraoperative examinations in 1,841 patients was performed in fractures of the calcaneus (20.5%) and the upper ankle joint (13.2%). Altogether we improved the reduction or the implant position intraoperatively in 21.5%. The majority of intraoperative revisions was seen in osteosynthesis of the calcaneus (40.3%), the upper ankle joint (30.9%) and fractures of the distal tibia (29%). The rate of revisions over the time was very stable. Intraoperative need for revision of reduction or implant position is not a rare phenomenon in our experience. Intraoperative 3D imaging is a valid tool to recognize and adjust suboptimal reduction or implant positioning. Intraoperative 3D imaging can improve the quality of osteosynthesis especially in fractures of joints and complex anatomical areas.

Cystic pseudotumours in both upper ankle joints in gouty arthritis.

This case demonstrates a yet unreported clinical entity of bilateral tophaceous cystic lesions of the tibiotalar joints of an 37-year-old white male who presents with moderate painful swelling in both upper ankle joints for 2 years. Radiodiagnostic studies show cystic lesions in both upper ankle joints and the right talus considering neoplastic processes in the differential diagnosis. The incisional biopsy reveals chalk-like material of the intraosseous lesions which was pathognomonic for tophaceous gout. Antihyperuricemic medication led to a stagnation of growth of the lesions without a sign of osseous remodeling. However, due to limitation of discomfort, personal preferences and a lack of surgical options conservative treatment was maintained.

[Tibiotalocalcaneal corrective arthrodesis in Charcot arthropathy of the ankle with a retrograde nail]. / Tibiotalokalkaneare Korrekturarthrodese bei Charcot-Arthropathie des oberen Sprunggelenks mit dem retrograden Nagel.

BACKGROUND: Involvement of the ankle joint in Charcot osteoarthropathy is most often associated with severe instability and fracture or collapse of the talus. Caused by malalignment, ulcerations over both malleoli are associated with increased risk of major amputation. OBJECTIVE: The goal of the operation is to realign the hind foot, gain a stable osteosynthesis, and prevent major amputation. INDICATIONS: Charcot osteoarthropathy of the ankle joint with instability, with or without soft tissue involvement, failure of the primary arthrodesis of the ankle or subtalar joint. CONTRAINDICATIONS: Acute osteitis/osteomyelitis, severe malalignment of the distal tibia, soft tissue infection close to the ankle joint. SURGICAL TECHNIQUE: Realignment of the hind foot, preparation of the joint surfaces using a transfibular approach. Bone grafting of the defects, stable osteosynthesis with an anatomically shaped retrograde locking nail. POSTOPERATIVE MANAGEMENT: Walker or cast for at least 12 weeks, 6 weeks no weight bearing. Partial weight bearing starting from week 7. X-ray control at 2, 6, and 12 weeks. After 12 weeks, walking in an ankle brace until fully consolidated.

[Intraoperative three-dimensional navigation for pedicle screw placement]. / Navigation an der Brust- und Lendenwirbelsäule mit dem 3D-Bildwandler.

The mobile SIREMOBIL Iso-C(3D) C-arm (Siemens, Erlangen, Germany) is the first device permitting intraoperative, three-dimensional representation of bone structures. A high-resolution, isotropic 3D data cube in the isocenter with sides of approximately 12 cm is calculated simultaneously. The SIREMOBIL Iso-C(3D) is linked to the navigation system. This makes it possible to transfer the generated 3D data directly to the linked navigation system without the need for surgeon-dependent registration. In this prospective clinical trial, we evaluated the accuracy of pedicle screw placement using this device. In 61 patients, a total of 302 pedicle screws were placed. Only in five cases (1.7%) were misplacements of > or =2 mm shown in postoperative control CT. The average fluoroscopy time was 1.28+/-0.56 min, and the average operative duration was 103.26+/-23.3 min. There were no postoperative neurological complications in any of the 30 patients. From these data, we conclude that Iso-C(3D) navigation is a very accurate method for the placement of pedicle screws.

[Postoperative malrotation after closed reduction and intramedullary nailing of the femur: a retrospective 5-year analysis]. / Postoperative Torsionsdifferenz nach unaufgebohrter antegrader Marknagelosteosynthese des Femurs: eine retrospektive 5-Jahres-Analyse.

BACKGROUND: Minimally invasive treatment of diaphyseal femur fractures (DFF) with closed reduction and intramedullary nailing is a well established procedure. However, a femoral malrotation after intramedullary nailing is considered to be a substantial problem. Studies have described femoral malrotation (FMR) in 17-35 % after this procedure. Computed tomography (CT) of both femora is accepted as an objective, reproducible measurement method to determine a postoperative femoral malrotation. An anatomic reposition of the centreline of the femur remains of high importance since a malrotation > 15° can lead to a significant limitation of the range of motion (ROM) and to clinical symptomatic constraints. PATIENTS/MATERIAL AND METHODS: Between July 2007 and December 2011 patients with unilateral DFF were treated with closed reduction and intramedullary nailing. Exclusion criteria were defined as bilateral or prior treatment for femoral fractures, open epihyseal plate or pregnancy. In all cases a postoperative CT scan of the femora was conducted to analyse a femoral malrotation. The indication for a correction was posed in cases of a malrotation > 15°. The data were not randomised and evaluated retrospectively. RESULTS AND CONCLUSION: In total 94 patients with unilateral DFF were included. 21 female and 73 male with an average age of 33.15 ± 14.04 years (range 14-94). In the postoperative CT scan an average FMR of 11.58 ± 9.41° (range 0-44°) was determined. In 15 cases (15.95 %), 10 male (13.7 %) and 5 female (23.81 %) a FMR > 15° (average: 23.66 ± 5.74°) was noticed. A subsequent surgery with a correction in average of 17.53 ± 6.83° was performed. After the correction the malrotation averaged 6.07 ± 5.61°. The results support the existing data that the treatment of DFF with closed reduction and intramedullary nailing may lead to a significant femoral malrotation despite a precise intraoperative monitoring. The data demonstrate that nearly 15 % of all patients appear after closed reduction and intramedullary nailing with a femoral malrotation greater than 15°. A routinely utilised postoperative CT scan provides additional information to discover an occult malrotation. CONCLUSION: In spite of diligent attendance to the femoral torsion intraoperatively in DFF a significant femoral malrotation may result after closed reduction and intramedullary nailing. To prevent a limitation of ROM and clinical constraints a routinely performed postoperative CT scan with a adequate surgical correction is recommended.

Characteristics of two different locking compression plates in the volar fixation of complex articular distal radius fractures.

OBJECTIVES: To investigate the differences of open reduction and internal fixation (ORIF) of complex AO Type C distal radius fractures between two different models of a single implant type. METHODS: A total of 136 patients who received either a 2.4 mm (n = 61) or 3.5 mm (n = 75) distal radius locking compression plate (LCP DR) using a volar approach were followed over two years. The main outcome measurements included motion, grip strength, pain, and the scores of Gartland and Werley, the Short-Form 36 (SF-36) and the Disabilities of the Arm, Shoulder, and Hand (DASH). Differences between the treatment groups were evaluated using regression analysis and the likelihood ratio test with significance based on the Bonferroni corrected p-value of < 0.003. RESULTS: The groups were similar with respect to baseline and injury characteristics as well as general surgical details. The risk of experiencing a complication after ORIF with a LCP DR 2.4 mm was 18% (n = 11) compared with 11% (n = 8) after receiving a LCP DR 3.5 mm (p = 0.45). Wrist function was also similar between the cohorts based on the mean ranges of movement (all p > 0.052) and grip strength measurements relative to the contralateral healthy side (p = 0.583). In addition, DASH and SF-36 component scores as well as pain were not significantly different between the treatment groups throughout the two-year period (all p ≥ 0.005). No patient from either treatment group had a step-off > 2 mm. CONCLUSIONS: Differences in plate design do not influence the overall final outcome of fracture fixation using LCP.

Validation of a statistical shape model-based 2D/3D reconstruction method for determination of cup orientation after THA.

PURPOSE: The aim of this study was to validate the accuracy and reproducibility of a statistical shape model-based 2D/3D reconstruction method for determining cup orientation after total hip arthroplasty. With a statistical shape model, this method allows reconstructing a patient-specific 3D-model of the pelvis from a standard AP X-ray radiograph. Cup orientation (inclination and anteversion) is then calculated with respect to the anterior pelvic plane that is derived from the reconstructed model. MATERIALS AND METHODS: The validation study was conducted retrospectively on datasets of 29 patients (31 hips). Among them, there were 15 men (15 hips) and 14 women (16 hips). The average age of the patients was 69.4±8.5 (49-82) years. Each dataset has one postoperative X-ray radiograph and one postoperative CT scan. The postoperative CT scan for each patient was used to establish the ground truth for the cup orientation. The cup anteversion and inclination that were calculated from the 2D/3D reconstruction method were compared to the associated ground truth. To validate reproducibility and reliability, two observers performed measurements for each dataset twice in order to measure the reproducibility and the reliability of the 2D/3D reconstruction method. RESULTS: Our validation study demonstrated a mean accuracy of 0.4 ± 1.8° (-2.6° to 3.3°) for inclination and a mean accuracy of 0.6±1.5° (-2.0° to 3.9°) for anteversion. Through the Bland-Altman analysis, no systematic errors in accuracy were detected. The method showed very good consistency for both parameters. CONCLUSIONS: Our validation results demonstrate that the statistical shape model-based 2D/3D reconstruction-based method is an accurate, consistent, and reproducible technique to measure cup orientation from postoperative X-ray radiographs. The best results were achieved with radiographs including the bilateral anterior superior iliac spines and the cranial part of non-fractured pelvises.

[Determining the femoral antetorsion angle with a fluoroscopy-based optoelectronic navigation system: a precision analysis]. / Bestimmung des Femur-Antetorsionswinkels mit einem fluoroskopiebasierten optoelektronischen Navigationssystem : Eine Genauigkeitsanalyse.

According to the literature, differences in torsion of 15 degrees and more develop in 20-30% of cases after intramedullary nailing of femoral shaft fractures. A computer-assisted method makes it possible to determine the antetorsion angle during surgery. In this experimental study, the precision of the measurements obtained with the navigation system were checked with a femur model and compared with a CT reference method. The measurements are carried out on a femur model that is equipped with a rotation device in the middle of the shaft. Nine reproducible angles can be set. Two investigators each conduct the measurements of the antetorsion angle ten times. A comparison is drawn between the absolute values of the antetorsion angle measured and the difference values of the adjoining positions. When comparing the absolute values of the navigation and reference systems, the mean deviations of both methods are around 1 degrees (0.35; 1.75) and comparing the differences 0.5 degrees (-0.2; 1.17). The maximum deviation of the absolute values of the CT reference method amounts to 6.4 degrees . Under experimental conditions, measurement of the femoral antetorsion angle proved to be sufficiently precise for clinical specifications in comparison to a CT reference method.

Stiffness measurement of the neocallus with the Fraktometer FM 100.

INTRODUCTION: The assessment of fracture healing is subjective, and neither radiology nor manual examination allows a reliable determination of bone healing. Fracture healing control in the treatment of tibia shaft fracture with external fixator by a stiffness measurement system (Fraktometer FM 100) is known from clinical studies. The purpose of this study was to follow stiffness control at external fixator in healing of callotasis with the stiffness measurement system. MATERIALS AND METHODS: From 1994 to 1997 stiffness measurements with the described system (Fraktometer FM 100) were performed in the BG-Clinic Ludwigshafen to assess the healing course in 11 cases of callotasis at lower limb. RESULTS: In ten cases, regular healing could be followed by signal decrease; in one case, a persistent signal without tendency to decrease was able to reveal callotasis failure at an early point of time. The investigation could also show the importance of bending stiffness control. One case of late axis deformation after fixator removal occurred because of disregarding delayed bending signal decrease. CONCLUSION: Measurements of the external fixator's stiffness after callotasis can provide useful additional information for further treatment strategy.

[Iso-C(3D0-assisted) navigated implantation of pedicle screws in thoracic lumbar vertebrae]. / Iso-C(3D)-gestützte navigierte Implantation von Pedikelschrauben an BWS und LWS.

The mobile Siremobil Iso-C(3D) C-arm (Siemens AG, Medical Solutions, Erlangen) is the first device that permits the intraoperative three-dimensional (3D) representation of bone structures. A high-resolution isotropic 3D data cube in the isocenter with an edge length of approximately 12 cm is calculated simultaneously. The Siremobil Iso-C(3D) is linked to navigation with the integrated NaviLink interface (Siemens AG, Medical Solutions, Erlangen). This makes it possible to transfer the generated 3D data directly to the linked navigation system Surgigate (Medivision, Oberndorf, Switzerland). In this prospective clinical trial we evaluated the accuracy of pedicle screw placement using the Siremobil Iso-C(3D) C-arm. The results were compared to the conventional approach and other computer-assisted procedures (CT-based navigation, C-arm-based 2D navigation) in historical control groups. A total of 141 pedicle screws were placed in 30 patients (70 thoracic spine, 71 lumbar spine). Only in one single case was misplacement shown in the postoperative control CT scan (0.71%), the lowest rate of incorrect placements of all techniques. Also the lowest average fluoroscopy time (1.28+/-0.56 min) was achieved during the placement of pedicle screws on the spine with Iso-C(3D) navigation at a comparable average OR duration (103.26+/-23.3 min). There were no postoperative neurological complications in all 30 patients. From these data we conclude that Iso-C(3D) navigation of pedicle screws is a very accurate method in the correct placement of pedicle screws.

[CT-free image guided acetabulum navigation in clinical routine]. / Die CT-freie bildgesteuerte Pfannennavigation in der klinischen Routine.

After experimental and preclinical evaluation (HAP Paul Award 2001) of the CT-free image-guided surgical navigation system for acetabular cup placement (SurgiGATE C-arm cup" by Medivision, Switzerland), the system was introduced into clinical routine. The computation of the angular orientation of the cup is based on reference coordinates from the anterior pelvic plane concept. A hybrid strategy for pelvic landmark acquisition has been introduced involving percutaneous pointer-based digitization with the noninvasive biplanar landmark reconstruction using multiple registered fluoroscopy images. From January 2001 to December 2002, a total of 256 consecutive patients with primary osteoarthrosis (mean age 69 years, 161 male, 95 female, 132 left, and 124 right hip joints) were operated on with the hybrid CT-free navigation system. During each operation the angular orientation of the inserted implant was recorded. To determine the placement accuracy of the acetabular components, 50 consecutive patients underwent a CT scan 7-10 days postoperatively to analyze the cup position related to the anterior pelvic plane. This was all done blinded by the same investigator with the planning software of the CT-based navigation system of Medivision. There was no significant learning curve observed for the use of the system. The mean value for postoperative inclination was 43 degrees (SD 3.0, range: 37 degrees -49 degrees ) and for anteversion 19 degrees (SD 3.9, range: 10 degrees -28 degrees ). The resulting system accuracy, i.e., the difference between intraoperatively calculated cup orientation and postoperatively measured implant position showed a mean error of 1.5 degrees for the inclination (maximum 5 degrees, SD 1.1) and 2.4 degrees for the anteversion (maximum 6 degrees, SD 1.3). An accuracy of better than 5 degrees inclination and 6 degrees anteversion was achieved under clinical conditions, which implies that there is no significant difference in performance from the established CT-based navigation methods. Image-guided CT-free cup navigation provides a reliable solution for future THA.