Validation of a new and pre-validated set of non-invasive optical trackers used on the image-free physiopilot navigation system
Authors: R. Alho, F. Henderson, J. Clarke, F. Picard, A. Deakin
Journal: International Journal of Surgery (2015)

s / International Journal of Surgery 23 (2015) S15eS134 S85 Aim: This study aimed to validate the repeatability of the assessment of anteroposterior (AP) knee joint laxity using a non-invasive image free navigation system in normal, healthy subjects. Validation of this technology could aid clinicians in identifying and quantifying ligamentous injuries in a clinical setting. Methods: Twenty-five healthy volunteers were recruited and examined in a single centre. The Lachman test was performed through flexion on both knees of each volunteer. AP translation was measured by an infrared camera and externally mounted optical trackers which transferred the data into the computer. Coefficients of Repeatability (CR) and Interclass Correlation Coefficients (ICC) were used to validate AP translation. Results: Themost reliable and repeatable AP translation assessments were at 30 and 45 , demonstrating good reliability (ICC 0.82, 0.82) and good repeatability (CR 2.5, 2.9). The AP translation assessment at 0 , 15 , 75 and 90 demonstrated moderate reliability (ICC 0.75), and poor repeatability (CR 3.0 mm). Conclusion: The non-invasive systemwas able to reliably and consistently measure AP knee translation between 30 and 45 flexion, the clinically relevant range for this assessment. This system could therefore be used to quantify abnormal knee laxity and improve the assessment of knee instability in the clinical setting. 0541: VALIDATION OF A NEW AND PRE-VALIDATED SET OF NONINVASIVE OPTICAL TRACKERS USED ON THE IMAGE-FREE PHYSIOPILOT NAVIGATION SYSTEM R. Alho , F. Henderson , J. Clarke , F. Picard , A. Deakin . Golden Jubilee National Hospital, UK; 2 Strathclyde University, UK Aim: The investigation aimed to validate a new set of optical trackers against a pre-validated set of optical trackers, and to determine the repeatability of the new optical tracker set. Methods: Two examiners assessed the supine mechanical femoro-tibial alignment (MFTA) and Lachman test on each other. The assessments were performed 10 times with each tracker on each knee. The non-invasive system consisted of an infrared camera, externallymountedoptical trackers and computer software. Validation of each tracker setwas assessed through inter-examiner repeatability, with the acceptable limits of agreement set at 2 for the supine MFTA, and 3mm for anteroposterior (AP) translation. Results: The pre-validated optical trackers demonstrated a more consistent supine MFTA acquisition in coronal alignment compared to the new tracker, with a range of +/ 2 and +/ 6 respectively. The pre-validated tracker set recorded higher levels of AP translation than the new tracker set, however the results were more consistent with the pre-validated set, with smaller standard deviation per knee. Conclusion: The optimal tracker set was the pre-validated set, which demonstrated better repeatability and comparability between both examiners at acquiring supine MFTA, and AP translation assessments than the new tracker set. 0548: THE QUALITY OF ANATOMICAL RESTORATION FOLLOWING DISTAL RADIUS FRACTURE FIXATION USING VOLAR PLATING SYSTEM Z. Sajjad , S. Ismael , S. Mahmoud , A. Logan . Glangwili General Hospital, UK; University Hospital Wales, UK Aim: Aim of the study is to evaluate the quality of distal radius anatomical restoration following distal radius fractures fixation. Methods: We carried out a retrospective observational study evaluating anatomical measurements, using x ray films at (0 and 6 weeks). A cohort of 120 cases distal radius fractures between May 2011 and January 2013 treated with volar plating system at University Hospital of Wales were reviewed. Only 73 cases were considered to fit the inclusion and exclusion criteria of distal radius fractures. The distal radius anatomical measurements; were calculated both pre and post-operatively. A basic statistical analysis was carried out. Results: 72.6% of fractures involved the dominant hand. 71% of our cohort was female. The majority of fractures were type C (42%), followed by Type A (32.9%) and B (24.7%). The mean agewas 56 years old for both genders. In all cases, radial height improved from (mean) 10.2 mm preoperatively to 11.3 mm post-operatively. The palmar tilt had acceptable results from a mean of 2.4 to 5.9 post-operatively. The average time from injury to operation was 5.14 days. Conclusion: At the University Hospital of Wales, the main anatomical measurements closely linkedwith good outcomes have been acceptably restored in most cases of distal radius fractures that have been plated. 0578: SOFT TISSUE INFECTIONS ASSOCIATED WITH LEGAL HIGHS: AN INCREASING PROBLEM L. Robiati, A. Vats, K. Bugler, T. White, J. Reid. Royal Infirmary of Edinburgh,