Radiographic outcomes in the coronal plane with iASSIST™ versus optical navigation for total knee arthroplasty: A preliminary case-control study.

BACKGROUND: The new navigation system iASSIST™ for total knee arthroplasty (TKA) relies on accelerometers and gyroscopes. The objective of this prospective study was to compare the accuracy of iASSIST™ to that of the conventional optical navigation system Navitrack™ by determining the rate of mechanical axis restoration (±3°), postoperative mean mechanical alignment, rate of adequate femoral and tibial component positioning, mean operative time, and occurrence of navigation-related adverse events. HYPOTHESIS: The rate of mechanical axis restoration (±3°) is not lower with iASSIST™ than with the conventional navigation system Navitrack™. MATERIAL AND METHODS: Of 40 patients who underwent primary TKA between October 2013 and March 2014, 20 had navigation using iASSIST™ and 20 using Navitrack™. Six months after TKA, an independent observer measured three parameters on coronal radiographs: the hip-knee-ankle angle (HKA), the mechanical lateral distal femoral angle (mLDFA), and the mechanical medial proximal tibial angle (mMPTA). RESULTS: The two groups showed no significant differences for the rates of HKA restoration (P=0.3), adequate coronal positioning of the femoral component (P=0.12) and tibial component (P=0.12), or optimal success (P=0.09). Significant differences in favour of iASSIST™ were demonstrated for the values and angular deviations of the HKA (P=0.02) and mMPTA (P=0.01), whereas no significant difference was found for mLDFA. There were no significant differences regarding the mean operative time (P=0.06) or the occurrence of navigation-related adverse events (P=0.18). DISCUSSION: The iASSIST™ system provides a neutral mechanical axis and optimal component position in the coronal plane in 95% of cases, indicating that it is as accurate as the optical navigation system Navitrack™. LEVEL OF EVIDENCE: III, prospective case-control study.

Ankle fractures in the elderly: Treatment and results in 477 patients.

INTRODUCTION: In the elderly, ankle fractures are likely to cause specific complications and have a major impact on their autonomy. The goal of this multicentre study was to assess these outcomes in a geriatric population treated operatively. MATERIAL AND METHODS: This retrospective study included 477 patients with ankle fractures treated surgically between 2008 and 2014. The minimum age was 60years for women and 70 for men. Patients with a tibial pilon fracture or less than 3months' follow-up were excluded. Functional (autonomy and comorbidities) and radiological assessments were performed before surgery and at the review. RESULTS: The cohort was 81% female (384 women, 93 men) and had median age of 74years. The preoperative autonomy was 7.8 points on average using the Parker score. Most of the fractures were either Weber type B (n=336) or type C (n=114). At the follow-up, the mean autonomy score was 7.3 points. The fibula was fixed with a plate and screws in 69% of cases (n=325), with additional internal malleolar fixation was carried out in some cases. A satisfactory result, defined as 2 points or less reduction in the Parker score, was found in 89.9% of patients; 71.8% had not lost any autonomy. The main risk factors for loss of autonomy were being more than 80years of age (OR=2.93, P<0.001), poor surgical reduction (OR=2.8, P<0.01), the presence of two or more comorbidities (OR=2.71, P<0.001), being female (OR=2.19, P<0.043) or having a Weber type C fracture (OR=2.05, P=0.023). DISCUSSION: The functional results are satisfactory overall following standard surgical treatment consisting of internal malleolar and fibular fixation for ankle fractures in the elderly. We identified five factors that greatly impact functional recovery. LEVEL OF EVIDENCE: IV.

Influence of experience on intra- and inter-observer reproducibility of the Crowe, Hartofilakidis and modified Cochin classifications.

INTRODUCTION: A previous study demonstrated that the reproducibility of the Crowe (Cr), the Hartofilakidis (Ha) and the modified Cochin (Co) classifications were comparable. However, there were differences with a trend that suggested the influence of experience. Therefore, we performed a prospective study to investigate whether experience influenced the reproducibility of the commonly used developmental dysplasia of the hip (DDH) classifications. HYPOTHESIS: The hypothesis was that the intra- and inter-observer reproducibility scores would be higher in the senior group than the junior group, and particularly for the modified Co classification. METHODS: Four seniors and four residents classified 104 A/P pelvic radiographs (200 hips) two times using the Cr, Ha and Co classification systems. RESULTS: For intra-observer reproducibility, the average weighted concordance coefficients [95% confidence intervals] were for the senior and the junior groups: 92.2 [88.6-95.7] and 92.6 [87.9-97.2] for Cr, 92.1 [88.7-94.6] and 92.0 [87.7-96.3] for Ha, 94.2 [91.8-96.6] and 94.1 [91.5-96.6] for Co. The average weighted Kappa (95% confidence intervals) were 0.8 [0.71-0.88] and 0.79 [0.68-0.89] for Cr, 0.77 [0.74-0.81] and 0.75 [0.62-0.88] for Ha, 0.82 [0.76-0.89] and 0.80 [0.74-0.87] for Co. The junior inter-observer reproducibility multi-rater Kappa (list A:list B) were 0.57:0.50 (Cr), 0.47:0.53 (Ha), 0.42:0.42 (Co). Senior multi-rater Kappa were 0.53:0.49 (Cr), 0.40:0.34 (Ha), 0.40:0.43 (Co). CONCLUSIONS: Contrary to our hypothesis, the experience of the observer did not affect the intra- and inter-observer reproducibility of the three classification systems.