Stefan Zech

A comparison of plates with and without locking screws in a calcaneal fracture model.

Background: We compared different plates in an experimental calcaneal fracture model under biocompatible loading. Methods: Four plates were tested: a plate without locked screws (Synthes), and three different plates with locked screws (Newdeal, Darco, Synthes). Synthetic calcanei (Sawbone) were osteotomized to create a fracture model, and the plates were fixed onto them. Seven specimens for each plate model were subjected to cyclic loading (preload 20 N, 1,000 cycles with 800 N, 0.75 mm/s), and load to failure (0.75 mm/s). Motion, forces, plastic deformation of the plate, and consequent depression of the posterior joint facet were analyzed. Results: During cyclic loading, all plates with locked screws showed statistically significant lower displacement in the primary loading direction than the plates without locked screws. Mean values (mm) of maximal displacements for each plate during cyclic loading were as follows: Synthes, 3.5; Darco, 4.5; Newdeal, 5.0; Synthes without locked screws, 7.5; (p < 0.001). No statistically significant differences between the plates were found in relation to loads to failure and corresponding displacement. Conclusion: This is the first biomechanical study to assess the stability of different plates currently in use in our practice for the fixation of calcaneal fractures. Our results showed that plates with locked screws provided greater stability during cyclic loading than the plate without locked screws.

Intraoperative 3D imaging in calcaneal fracture care-clinical implications and decision making.

BACKGROUND In operative calcaneal fracture care malposition of screws and joint line incongruity frequently remain unrecognized using fluoroscopy intraoperatively, and are frequently only recognized on postoperative computed tomography scans. The purpose of this study was to analyze the feasibility and utility of a new C-arm-based three-dimensional imaging technology for calcaneal trauma care. METHODS The C-arm-based three- dimensional imaging device (ISO-C-3D) was used in 32 patients during a 2-year period. Patients were indicated for open reduction and internal fixation using standard techniques and fluoroscopy. After reduction and implant placement was determined to be correct, the ISO-C-3D procedure was performed. The time for setup and use, and the consequences were recorded. An assessment was obtained from the surgeon regarding the feasibility and the adequacy and quality of the data provided, using a Visual Analog Scale. RESULTS The average total time required for ISO-C-3D use was 610 seconds. The information obtained from the scan led the surgeon to alter the reduction or screw placement during the procedure in 41% of the patients. Surgeons rating according to a Visual Analog Scale: feasibility 9.5, accuracy and quality 9.2, clinical benefit 8.2. CONCLUSION Intraoperative three- dimensional visualization with the ISO-C-3D provides important information in the operative treatment of calcaneal fractures which cannot always be obtained from plain films or standard fluoroscopy alone. The use of the device adds minimal time to the overall procedure, and was found to be extremely useful in evaluating reduction and implant position intraoperatively in calcaneal fractures.

Intraoperative 3-Dimensional Imaging in Foot and Ankle Trauma : Experience With a Second-Generation Device (ARCADIS-3D)

Objective: Intraoperative 3-dimensional imaging with the first available device (ISO-C-3D; Siemens, Germany) has shown potential benefit in foot and ankle surgery. The aim of the study was to assess the clinical use of the second-generation device (ARCADIS-3D; Siemens) in comparison with earlier experience with the first-generation device. Methods: In a matched pair study, the ISO-C-3D/ARCADIS-3D was used for intraoperative visualization after reduction/correction and internal fixation. The ISO-C-3D was used in 62 cases between January 1, 2003, and March 15, 2004, and the ARCADIS-3D was used in cases with similar fractures and arthrodesis location between September 1, 2006, and April 30, 2008. Potentially, changes in implant position and/or reduction were made after device use. Time spent and changes resulting from the use of ISO-C-3D/ARCADIS-3D were registered and analyzed. Results: On average, the operation was interrupted for 440/320 seconds (ISO-C-3D/ARCADIS-3D), 120/60 seconds, on average, for the scan, and 210/180 seconds, on average, for evaluation of the images by the surgeon. In 39%/34% of the cases (24/21 of 62), the reduction and/or implant position was corrected during the same procedure after the ISO-C-3D/ARCADIS-3D scan. Conclusions: Intraoperative 3-dimensional visualization with the ISO-C-3D/ARCADIS-3D can provide useful information that cannot be obtained from plain films or conventional C-arms. The second-generation device (ARCADIS-3D) provides faster scan and evaluation that reduces time spent. No other benefits were seen.

PedCAT for 3D-imaging in standing position allows for more accurate bone position (angle) measurement than radiographs or CT

BACKGROUND PedCAT (Curvebeam, Warrington, USA) is a new technology that allows 3D-imaging with full weight bearing which is not influenced by projection and/or foot orientation (as radiographs). The aim of this study was to compare time spent of the image acquisition, and comparison of specific bone position (angle) measurements between three imaging methods (radiographs, CT, pedCAT), and to analyze and compare measurement differences and inter- and intraobserver reliability. METHODS In a prospective consecutive controlled study, 30 patients in which standard digital radiographs with full weight bearing in standing position (feet bilateral dorsoplantar and lateral views and Saltzman hindfoot view), CT without weight bearing, and pedCAT scan with full weight bearing in standing position were included, starting July 1, 2013. The following angles were measured for the right foot by three different investigators three times: 1st - 2nd intermetatarsal angle, talo-metatarsal 1-angle (TMT) both dorsoplantar and lateral projection, hindfoot angle, calcaneal pitch. The angles were digitally measured and compared (ANOVA with Post Hoc Scheffe test). RESULTS The angles differed between radiographs, CT and pedCAT (ANOVA, all p≤.01). The angles differed between pedCAT and both radiographs and CT (Post Hoc Scheffe test, each p≤.05 except for TMT dorsoplantar and calcaneal pitch angels versus radiographs). CONCLUSIONS The angles differed between radiographs, CT and pedCAT, indicating that only pedCAT is able to detect the correct angles. PedCAT includes weight bearing in contrast to CT. PedCAT prevents inaccuracies of projection and foot orientation in contrast to radiographs due to the 3D dataset which is principally independent from projection and foot orientation.

Intraoperative Pedography: A Validated Method for Static Intraoperative Biomechanical Assessment

Background: A new device was developed to perform intraoperative static pedography. The purpose of this study was to validate the introduced method by a comparison with the standard method for dynamic and static pedography. Methods: A device known as Kraftsimulator Intraoperative Pedographie® (KIOP®) was developed for intraoperative placement of standardized forces to the sole of the foot. Pedographic measurements were done with a custom-made mat that was inserted into the KIOP® (Pliance®, Novel Inc., St. Paul, MN, USA). Validation was done in two steps: (1) comparison of standard dynamic pedography walking on a platform, standard static pedography in standing on a platform, and pedography with KIOP® in supine position in 30 healthy volunteers, and (2) comparison of static pedography in standing position, pedography with KIOP® supine awake, and pedography with KIOP® supine with 30 patients under anesthesia. Individuals who had operative procedures at the knee or distal to the knee were excluded. The different measurements were compared (one-way ANOVA, t-test; significance level 0.05). Results: No significant differences were found among all measurements for the hindfoot compared to midfoot-forefoot force distribution. For the medial compared to lateral force distribution and the 10-region-mapping, significant differences were found when comparing all measurements (steps 1 and 2) and when comparing the measurements of step 1 only. No differences were found for these distributions when comparing the measurements of step 2 alone or when comparing the measurements of step 1 and 2 without the platform measurements of step 1 (dynamic walking pedography and static standing pedography). No significant differences in the force distributions were found in step 2 when comparing subjects without anesthesia, with general anesthesia, and with spinal anesthesia. Conclusions: The KIOP device allows a valid static intraoperative pedography measurement. No statistically significant force distribution differences were found between standing subjects and anesthetized subjects in the supine position.

Long term results after multiple injuries including severe head injury.

OBJECTIVE To describe the long term results in patients with multiple injuries including severe head injury. DESIGN Retrospective and prospective clinical study. SETTING Level I trauma centre, Germany. PATIENTS Patients aged 16-60 years who had been injured more than 2 years before, whose Injury Severity Score was over 20 and whose cranial Abbreviated Injury Score (AIS) was over 3. MAIN OUTCOME MEASURES Glasgow Outcome Scale (GOS), functional, neuropsychological, vocational and social outcomes. RESULTS 58 patients, median age 24 (range 16-53, interquartile range (IQR) 21-32) years were investigated 5 (3-9; IQR 4-7) years after their injury. Median ISS was 34 (21-57; IQR 26-41) and GCS 6 (3-8; IQR 4-7). Duration of coma was 10 (2-51; IQR 7-22) days and neurological rehabilitation lasted 169 (10-830; IQR 80-300) days. Movements of the elbow and ankle was most impaired by injury. All psychometric tests showed deficits, particularly in speed of processing, concentration, recent memory, and learning performance. The social environment had been changed in half and vocational rehabilitation was dependent on age. 24 (42%) returned to their former profession, 18 (31%) were retrained to another profession, 16 (27%) were unemployed or retired on a pension. 31 (53%) made a good recovery with moderate disability, 19 (33%) had severe disability, and 8 (14%) remained in a persistent vegetative state assessed by the GOS. CONCLUSION Early and concentrated rehabilitation facilitates functional, social, and neuropsychological reintegration.

Differences in the mechanical properties of calcaneal artificial specimens, fresh frozen specimens, and embalmed specimens in experimental testing

Background. Artificial calcanei, fresh-frozen cadaver specimens, and embalmed cadaver specimens were compared in experimental testing under biocompatible loading to clarify the biocompatibility of artificial calcaneal specimens for implant testing. Methods. Two different artificial calcaneal bone models (Sawbone™, Pacific Research Laboratories, Vashon, WA, and Synbone™, Synbone Inc., Davos, Switzerland), embalmed cadaver calcaneal specimens (bone density, 313.1 ± 40.9 g/cm 2 age, 43.8 ± 7.9 years), and fresh-frozen cadaver calcanei (bone density, 238.5 ± 30.0 g/cm 2 age, 44.4 ± 8.2 years) were used for testing. Seven specimens of each model or cadaver type were tested. A mechanical testing machine (Zwick Inc., Ulm, Germany) was used for loading and measurements. Cyclic loading (preload 20 N, load was increased every 100 cycles by 100 N from 1,000 to 2,500 N, 0.5 mm/s) and load to failure (0.5 mm/s) were performed. The loads were applied through an artificial talus in a physiological loading direction. The displacement of the posterior facet in the primary loading direction was measured. Results. The four different specimen groups showed different stability and different displacement in the primary loading direction during cyclic loading. The variation of the maximal displacement in the primary loading direction for the entire cyclic loading was higher in artificial specimens than in the cadaver specimens. Conclusions. Artificial calcanei (Sawbone™, Synbone™) showed different biomechanical characteristics than cadaver bones (embalmed and fresh-frozen) in this experimental setup with biocompatible cyclic loading. These results do not support the use of artificial calcanei for biomechanical implant testing. Fresh-frozen and embalmed specimens seem to be equally adequate for mechanical testing. The low variation of mechanical strength in the unpaired cadaver specimens suggests that the use of paired specimens is not necessary.

Normative data of the Visual Analogue Scale Foot and Ankle (VAS FA) for pathological conditions

BACKGROUND The purpose of this study was to analyze the Visual Analogue Scale Foot and Ankle (VAS FA) in patients to obtain normative data for pathological conditions. METHODS The VAS FA was consecutively obtained in a foot and ankle outpatient clinic. The score results were categorized into different pathological foot and ankle conditions. RESULTS 414 patients were evaluated. Overall scores and score categories of all pathology groups differed from non-pathological data (n=121). Within the different groups, no score differences occurred. Score standards were defined for these groups with sufficient statistical power (>.8): isolated Hallux valgus, Hallux valgus and claw toes, forefoot other pathology, midfoot other pathology, hindfoot pathology and ankle deformity. No standards were defined for other pathology groups. CONCLUSIONS The obtained data is normative for different pathological conditions of the earlier validated VAS FA. The obtained data is normative for different pathological conditions of the earlier validated VAS FA. This data could serve as a basis for assessment patient scoring before, during and after treatment which has to then to be proved by ongoing research.

Computer Assisted Surgery (CAS) guided arthrodesis of the foot and ankle: an analysis of accuracy in 100 cases.

Background: Computer Assisted Surgery (CAS) has shown the potential to increase the accuracy of surgical procedures in different fields of orthopedic surgery. The clinical experiences of 100 cases with CAS guided arthrodeses were evaluated. Materials and Methods: Two navigation systems were used (VectorVision/Navivision, Brainlab). Patients with unilateral foot and/or ankle correction arthrodesis from January 1st, 2005 to March 31st, 2008 were included. The correction was planned on the basis of clinical findings, radiographs and computer tomography. Time spent, accuracy, and problems that occurred with CAS guidance were analyzed. The accuracy was assessed by intraoperative three-dimensional imaging with ISO-C 3D or ARCADIS-3D (Siemens). The deviation from the achieved correction in comparison with the planned correction was analyzed. Results: One hundred patients were included (ankle, n = 19; subtalar, n = 23; ankle and subtalar, n = 12; midfoot/tarsometatarsal (TMT), n = 28, others, n = 18). The average time needed for preparation was 356 seconds (5 minutes, 56 seconds) (range, 4 to 30 minutes), the correction took an average of 28 (range, 12 to 140) seconds. The CAS system encountered malfunctions in 3 procedures (3%). In the remaining cases, all the achieved corrections were within a maximum deviation of 2 degrees/mm when compared to the planned correction (p < 0.05). Conclusion: With CAS guidance for the correction of deformities of the foot and ankle, a surgeon can achieve a high degree of accuracy with a rapid correction. The high accuracy may lead to improved clinical outcomes. Level of Evidence: IV, Retrospective Case Series

Initial Outcomes of 3-Dimensional Imaging-Based Computer-Assisted Retrograde Drilling of Talar Osteochondral Lesions

Background In operative treatment of Berndt and Harty stage 1 and stage 2 osteochondral lesions of the talus, the goal is revascularization. The use of computer-assisted guided retrograde drilling of osteochondral lesions has been described as a new technique with promising results. Purpose This study reports the follow-up assessment of patients treated with Iso-C-3D-navigated retrograde drilling. Its aim was to establish whether the greater precision of computer-assisted drilling results in satisfactory clinical outcomes. Study Design Case series; Level of evidence, 4. Methods Patients who underwent navigated Iso-C-3D-based retrograde drilling between June 1, 2003, and July 31, 2005, were included in the follow-up study. Clinical outcomes were measured using (1) the Ankle-Hindfoot Scale of the American Orthopaedic Foot and Ankle Society and (2) the Visual Analogue Scale—Foot and Ankle. Radiological outcomes were assessed via radiographs and magnetic resonance imaging. Surgeon satisfaction was assessed using a simple 0 to 10 rating scheme for feasibility, accuracy, and clinical benefit. Results Average follow-up time was 25 months (range, 20-34). Twenty patients satisfied the inclusion criteria: 12 men and 8 women; mean age, 35 years (range, 19-58). One patient was excluded because he required a cartilage restoration procedure. All scores improved at the time of follow-up—Ankle-Hindfoot Scale, from 76 to 90 (P < .001); Visual Analogue Scale—Foot and Ankle, from 79 to 92 (P < .001). The average ratings of the operating surgeons (n = 3) were as follows: feasibility 9.0 (range, 7.3-10.0); accuracy, 8.5 (range, 5.8-10.0); and clinical benefit, 8.5 (5.7-10.0). At follow-up, magnetic resonance imaging revealed an improvement of the Hepple score in 80% of patients. Conclusion Arthroscopic treatment of osteochondral lesions of the talus is well established. A retrograde approach does not breach the overlying intact talar cartilage. The results of this follow-up study of 3-dimensional computer navigated drilling are promising.