An accelerometer-based portable navigation system (KneeAlign2, OrthAlign Inc., Aliso Viejo, CA) is expected to improve mechanical axis and component alignment compared to conventional instrumentation in total knee arthroplasty (TKA). However, past reports have evaluated its accuracy using only radiographic measurements. The purpose of this study was to analyze the accuracy of the KneeAlign2 system with radiography and more detailed three-dimensional (3D) CT. We targeted 22 patients (24 knees) with severe osteoarthritis who underwent primary TKA using the KneeAlign2 system. Cemented, fixed-bearing, cruciate-retaining prostheses were implanted in all patients. We used postoperative standing-position full-length radiographic evaluation of the lower limbs to measure the hip-knee-ankle angle (HKA), frontal femoral component angle (FFC), and frontal tibial component angle (FTC). However, lower limb rotation and knee flexion could affect radiographic measurement of HKA and the component positioning angle. We used 3D bone models reconstructed from pre- and postoperative CT images to precisely analyze the 3D component positioning. For a 3D matching bone model made from these models, a 2D projection of the pre- and postoperative component positioning planes was made, and the projection angle was measured as angle error compared to the preoperative planned position (Figure 1). Average surgery time and total blood loss on postoperative day 7 were also recorded.INTRODUCTION
METHODS
Dysplastic hip has not only deficiency of acetabulum but also femoral deformity. Therefore, selection of stem is important in cementless THA for dysplasia. Especially using of short stem should be challenge for deformed femur. We studied clinical performance and radiological findings after THA with triple tapered short stem (Optimys hip) for dysplastic hip. From May 2013, we performed cementless THA for osteoarthritis with dysplasia. Seventy-one hips of 67 patients were examined including four males and 63 females. Age at surgery was from 36 to 88 years old (61.7 in average). Surgical approach was used modified Watson-Jones in all hips. Clinical evaluation was used modified Harris hip score (MHSS), incidence of complications and thig pain. Radiological findings were evaluated according Engh's classification and grade of stress shielding. Follow-up period was minimum one year and was 21.3 months in average.Introduction
Materials and method
Patient matched instrumentation (PMI) have been proposed the accuracy of bone cuts through custom cutting blocks and provide the proper alignment of total knee arthroplasty (TKA). On the other hand, there are some reports that the introduction of PMI for guiding bone cuts could increase the incidence of malalignment in primary TKA. Recent comparisons between patient-specific cutting guides and quantitative assessments of postoperative alignment have revealed the presence of outliers with respect to coronal alignment. The purpose of this study was to assess the implanted component alignment post-operatively between one type of MRI based PMI (Visionaire; Smith & Nephew, Inc, Memphis, Tenn) and conventional surgical instrumentation (CI) using radiographs and CT scan. 32 knees in 32 patients (25 women) with medial type knee osteoarthritis were underwent cruciate retaining TKA between September 2013 and May 2015, and were included in this study. Preoperative MRI scanning of the hip, knee, and ankle was performed for PMI group (n=12) and CT scanning was performed for CI group (n=20) 6 weeks before surgery according to a standard scanning protocol to determine the surgical epicondylar axis (SEA). Postoperatively, we compared operation time, blood loss, and mechanical alignment of two groups. Post-surgical mechanical alignments such as hip-knee-ankle angle (HKA), frontal femoral component angle (FFC), and frontal tibial component angle (FTC) were determined using long leg radiographs (Fig. 1). CT scans were used to assess the condylar twist angle (CTA) made by SEA and posterior condylar axis (Fig. 2). Each measurement was performed by two, blinded independent observers, and interclass correlation for each measurement was calculated. A student's two-tailed t test was used to compare the two cohorts, with statistical significance set at a p-value of <0.05.Introduction
Methods
Fixation patterns of cementless stem were known as proximal or distal part. Distal fixation was seen in fully porous coated stem and stress shielding of the proximal femur was indicative. These phenomena did not lower the clinical results, but technical difficulties were more and more in revision surgery because of infection or dislocation. There was lot of reports that alendronate was effective for treatment of osteoporosis by induction of apoptosis in osteoclasts. We can expect alendronate to modify the bone quality around the stem after cementless THA. We studied prospectively that quantitative computed tomography (QCT) measured bone mineral density around the stem between alendronate group and control. We tried to clarify that stress shielding after cementless THA can be prevented by use of alendronate or not.Introduction
Objectives
