Precise localization of silicone-based intercranial planar electrodes in magnetic resonance imaging.

Intercranial planar electrodes enable neural recordings with high spatial resolution in diagnosis as well as for treatments. The value of the measurements increases with the precision of localization of the electrodes related to the individual anatomy. In this context, post-implantation MRI provides excellent soft tissue contrast, but the accurate localization of electrodes is impaired by magnetic susceptibility artifacts. We have addressed this problem without adding a substantial burden to the electrode fabrication process. Simple silicone reference structures were strategically placed on the implant surface to visualize the electrodes position in MRI. These reference structures allowed high precision electrode localization independently of electrode imaging artifacts. This implant manufacturing approach could prove extremely useful in combination with existing image processing pipelines.

Comparison of interfragmentary compression in conventional and locked plating of proximal unicondylar tibia fractures : A biomechanical cadaver study.

The extent of interfragmentary compression in intra-articular fractures treated with various fixation methods have not yet been reported. Lateral split fractures were created in six pairs of cadaver tibiae treated -using buttress plating with lag screws (group C) or locked buttress plating after clamp compression (group L). Interfragmentary compression and fracture displacement were continuously measured using pressure sensors and a stereoscopic 3-D image correlation system. Significantly larger interfragmentary compression was found initially after clamping the fragment (p < 0.05) in group C (median ±â€ˆSD ; 45.1 ±â€ˆ5.0 N/mm2) compared with group L (33.6 ± 3.4 N/mm2), and a statistical trend towards larger compression was also found after cyclic loading (p = 0.05) in group C (45.3 ±â€ˆ8.6 N/mm2) compared with group L (28.7 ±â€ˆ5.8 N/mm2). These data indicate that conventional plating with lag screws achieves higher interfragmentary compression in this model compared with external clamp compression and locked plating.

Patient-reported outcome assessment after total joint replacement: comparison of questionnaire completion times on paper and tablet computer.

INTRODUCTION: Patient-reported outcome (PRO) assessment is becoming increasingly important after joint replacement surgery. However, PRO data collection, questionnaire handling, and data processing are time consuming and costly process. The aim of our study was to evaluate the efficiency of PRO assessment using tablet computers compared with traditional paper questionnaires in a total hip or knee arthroplasty (THR or TKR) population. MATERIALS AND METHODS: We recruited 100 patients from outpatient clinics attending for routine follow-up 2 months, 1 year, or 5 years after THR or TKR. Fifty patients completed the Western Ontario and McMaster Universities (WOMAC) osteoarthritis score and Forgotten Joint Score-12 (FJS-12) questionnaires on paper, and 50 patients completed these on a tablet computer. Questionnaire completion was timed for each PRO assessment and for manual data entry of the paper questionnaires into the database. The t test, Mann-Whitney U test, Fisher's exact test, and Wilcoxon test were used for statistical analysis. RESULTS: The mean age of the patients was 67.0 years (standard deviation 10.3 years), with no significant difference between the two groups. Median time for WOMAC questionnaire completion (including data entry for the paper questionnaires) was 197 s for the paper version and 117 s for the tablet version (p < 0.001). Median times for completion of FJS-12 were comparable for paper and tablet versions (32 vs. 37 s). We did not find a significant correlation between age and time for questionnaire completion. CONCLUSION: Electronic PRO data collection can substantially decrease time, logistics, and effort associated with questionnaire completion in daily clinical practice. It is also acceptable for use in an older arthroplasty population.

Mid term results of distal femoral fractures treated with a polyaxial locking plate: a multi-center study.

OBJECTIVE: Locking plates have become a standard implant in the treatment of distal femoral fractures. Newer designs allow polyaxial screw placement as well as the ability to lock the lag screws. METHODS: The consecutive multi-centre study cohort consists of all distal femoral fractures treated with the NCB® Distal Femur plate (Zimmer, Warsaw, USA) and a minimum follow-up of twelve months. Fracture classification according the AO/ OTA system and the trauma mechanism radiological evaluation and complications were documented. Clinical evaluation consisted of the Short Form SF12 questionnaire (SF12), the Hospital for Special Surgery Score (HSS) and clinical assessment of range of motion. RESULTS: Twenty-five patients with twenty-six fractures were available for follow-up with a minimum required follow-up of twelve months. 81% of the fractures were intra-articular. 48% of the patients were multi-traumatised, 38% having open fractures. All except two went to union (92%) with the primary procedure. The HSS Score was 79 (32-99) and the SF 12 (physical and mental) 40 (19-57) and 54 (21-66) at follow-up. There were five patients requiring surgical revision (19%). CONCLUSION: These fractures are often combined with concomitant injuries. Using modern locked implants high union rates can be achieved with a good function and patient satisfaction when respecting biologic and biomechanical principles.

[Periprosthetic fractures of the knee joint]. / Periprothetische Frakturen am Kniegelenk.

The demographic developments and an increasing number of total knee replacements will lead to more periprosthetic fractures in the future. These fractures can be classified into intraoperative and postoperative. Revisions in particular are associated with a higher incidence of intra-operative fractures, specifically for the tibia and patella. Most fractures occur in the postoperative period with an average of 2-4 years after the primary procedure. Most commonly the femur is involved. The history and clinical examination as well as imaging are crucial for the treatment as loose components would significantly alter the treatment strategy. In this case a revision has to be carefully planned. In the majority of the cases the prosthesis is well fixed especially at the femur. An open reduction internal fixation (ORIF) can then be carried out. A stable situation must be achieved to provide early post-operative mobilization. Also an anatomic reduction should be achieved with correct alignment especially with respect to varus/valgus and rotation. Modern locked implants can provide this with good success also with the possibility of minimally invasive techniques and polyaxial screw positioning. Retrograde intramedullary devices can be a feasible alternative. Similar principles can be used for the tibia whereas the patella can be stabilized with tension band wiring in the case of good bone stock but still remains a problem in case of bad bone stock.

Treatment of periprosthetic femur fractures with the non-contact bridging plate: a new angular stable implant.

OBJECTIVES: We report the application of a new fixed angle plate (NCB DF, Zimmer inc. USA, Warsaw, IN) in the treatment of periprosthetic femur fractures. The NCB DF combines conventional plating technique with polyaxial screw placement and angular stability. DESIGN: Prospective cohort study. SETTING: A single level-1 trauma center. PATIENTS: From May 2003 to December 2005, a total of 24 patients with periprosthetic femur fractures were treated. The NCB DF femur plate was used in all cases. The average follow-up period was 12 months (3-31 months). Twelve patients had a periprosthetic fracture after total knee replacement (TKA) and 12 patients after total hip replacement (THA). The mean period from primary joint replacement to periprosthetic fracture was 8.2 years for the THA group and 7.2 years for the TKA group. INTERVENTION: A combined conventional/locking surgical technique was performed in all the cases. MAIN OUTCOME MEASURES: Union, non-union, mal-union, duration of surgery, range of motion, postoperative mobility, subjective patient satisfaction and complications. RESULTS: The union rate was 90%, the mal-union rate 5% and the re-operation rate 15%. Postoperative mobility reached the preoperative level in all but for two patients. Three complications occurred relating to the implant or the procedure: one fatigue failure of the plate (non-union), one screw breakage, and one wound infection. CONCLUSIONS: The NCB DF combines conventional plating technique with polyaxial screw placement and angular stability. This combination technique shows promising results regarding union and mal-union rates in periprosthetic fractures in elderly and osteoporotic patients.

Prevention of recurrent acute otitis media: chemoprophylaxis versus tympanostomy tubes.

Otitis media has long been recognized as one of the most common diseases of childhood. Several therapeutic modalities have been advocated for the prevention of recurrent episodes of acute otitis media (AOM). A blinded, prospective, randomized study was designed to determine the efficacy of tympanostomy tubes, antibiotic prophylaxis, and placebo. Children with recurrent AOM were entered in the study and followed for at least 6 months. A total of 65 children completed the protocol. Sixty-three of those were under the age of 4 years. Treatment failure was defined as two or more episodes of AOM or otorrhea in less than 3 months. Five of 22 children in the tympanostomy tube group failed, compared to 12 of 20 in the placebo group (p = .02). There were 8 or 21 treatment failures in the sulfisoxazole group. Children with otitis media with effusion (OME) at the time of their initial visit had significantly less middle ear disease when treated with tympanostomy tubes. Tympanostomy tube insertion for prophylaxis of recurrent acute otitis is supported by these findings. Improvement of recurrent AOM was observed in the sulfisoxazole group, but was not statistically significant.