Similar radiological results with accelerometer-based navigation versus conventional technique in total knee arthroplasty.

BACKGROUND: The Zimmer iASSIST system is an accelerometer-based, portable navigation device for total knee arthroplasty (TKA) that does not require the use of a large console for alignment feedback as required in computer-assisted surgery. The purpose of this study was to determine the accuracy of the accelerometer-based system in component positioning and overall mechanical alignment. METHODS: Two groups of 30 patients each with primary osteoarthritis underwent TKA using either conventional method or Zimmer iASSIST navigation in 2013 was retrospectively studied. Patients were matched according to body mass index (BMI), gender and age. A senior arthroplasty surgeon performed all the operation using the same surgical approach. Perioperative and post-operative regimens were the same. All patients had standardized radiographs performed post-operatively to determine the lower limb mechanical alignment and component placement. RESULTS: There was no difference between the two groups for age, BMI, gender, side of operated knee and preoperative mechanical axis ( p > 0.05). There was no difference in the proportion of outliers for mechanical axis ( p = 0.38), coronal femoral angle ( p = 0.50), coronal tibia angle ( p = 0.11), sagittal femoral angle ( p = 0.28) and sagittal tibia angle ( p = 0.33). The duration of surgery, post-operative drop in haemoglobin level and transfusion incidence did not show statistically significant differences between the two groups ( p > 0.05). CONCLUSIONS: Our article showed that iASSIST was safe and remains a useful tool to restore mechanical axis. However, our data demonstrated no difference in lower limb alignment and component placement between the TKA that used accelerometer-based system and those that underwent conventional method.

Morphology and fixation pitfalls of a highly unstable intertrochanteric fracture variant.

PURPOSE: To describe a variant of intertrochanteric fracture not well-characterised in the existing classification systems. METHODS: 10 women and 2 men aged 59 to 98 (median, 80) years with intertrochanteric fractures characterised by a low intertrochanteric fracture, a basicervical fracture fragment, and a thin or fractured lateral wall with greater trochanteric comminution were reviewed. RESULTS: The 12 fractures were classified as A2.1 (n=1), A2.2 (n=7), A2.3 (n=1), and A3 (n=3) according to the AO/OTA classification, and as type 3 (n=2), type 5 (n=7), and type 6 (n=3) according to the Evans classification. The fractures were characterised by greater trochanter comminution and a coronal plane fracture extending into the greater trochanter resulting in a loss of superolateral support. Patients were treated with the Proximal Femoral Nail Antirotation (n=5), the Proximal Femur Locking Plate (n=6), or the reversed Less Invasive Stabilization System for distal femur (n=1). Within the mean follow-up period of 6 months, 3 patients with plating and one patient with nailing had mechanical failure defined as loss of alignment of >10º or screw cutout. CONCLUSION: This intertrochanteric fracture variant is highly unstable with a high failure rate. Loss of superolateral support rather than the medial calcar buttress is the main contributing factor to mechanical failure. Computed tomography is important in preoperative planning. Intramedullary nailing is more appropriate than extramedullary plating for such unstable fractures.

Risk factors of surgical site infections in hip hemiarthroplasty: a single-institution experience over nine years.

INTRODUCTION: This study aims to describe the factors associated with surgical site infection (SSI) in elderly patients who underwent hip hemiarthroplasty following a hip fracture, in a single institution over a nine-year period. METHODS: All patients who underwent hip hemiarthroplasty between 1 January 2004 and 31 December 2012 in our hospital were included in the present study. The detection of SSI was carried out by a trained, independent infection control nurse using the United States Centers for Disease Control and Prevention criteria. Demographic and clinical data were collected retrospectively. Demographics and clinical factors were analysed for potential associations with SSI. RESULTS: Among the 1,320 patients who met the study inclusion criteria, a total 57 SSIs were documented, giving an infection rate of 4.3%. Patients who waited for more than one week for surgery had a statistically significantly higher risk of SSI (odds ratio 3.030, 95% confidence interval 1.075-8.545, p = 0.036). The presence of SSI was also significantly associated with increased length of hospital stay (p < 0.001). The two main microorganisms detected were methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, which accounted for 50.9% and 26.3% of the SSIs, respectively. CONCLUSION: We concluded that the number of days from admission to surgery is a main risk factor for the development of SSI. Steps should, therefore, be taken to prevent unnecessary delay of surgery in elderly patients requiring hip hemiarthroplasty.