In recent literatures dealing with optimisation of prosthetic alignment in total hip arthroplasty (THA), the concept of combined anteversion (CA), sum of acetabular anteversion (AV) and femoral antetorsion (AT), has been addressed. We have been using an image-free THA navigation system?OrthoPilot THAPro?to achieve improved overall alignment with both stem and cup. In the use of this system, we have used the stem-first procedure so-called CA technique. In this technique, the femur was prepared first with the target angle corresponding to the native femoral AT and the cup AV was decided considering CA calculated with the formula of Widmer (37.3°= cup AV + 0.7 stem AT). The purpose of this study was to evaluate the accuracy of CA by using CA technique with image-free navigated THA. Fifty hips underwent primary THA using OrthoPilot THApro with CA technique. In CA technique, the femur was prepared first and the target angle of AT value was basically determined by for the individual native femoral AT angle. After the femur was prepared, the cup AV was decided based on the formula of Widmer. All included patients underwent postoperative CT examination, and the prosthetic alignment was assessed using the 3D-Template system (Zed Hip, LEXI).Introduction
Methods
Implant positioning is one of the critical factors influencing the postoperative outcome in total hip arthroplasty (THA). Conventional (manual) intraoperative stem adjustment may result in variability and inaccuracy of stem antetorsion (AT). Since March 2013, we have measured stem antetorsion with CT free Navigation system (OrthoPilot Navigation System THA Pro Ver4.2, B/Braun Aesculap Germany: Navi). We have developed a simple instrument, the Gravity-guide (G-guide), for intraoperative assessment and adjustment of stem AT. We evaluated the accuracy and effectiveness of G-guide and navigation software as referenced to postoperative CT evaluation with 3D template system (Zed hip, LEXI, Japan). Between March 2013 and December 2014, 50 patients underwent primary THA were evaluated. Surgeries were performed with routine techniques with a modified Hardinge approach with the patient at a lateral decubitus position in all cases. The G-guide consists of two parts: one attached to the lower leg and the other attached to the handle of the rasp. During surgery, AT value was determined with navigation at the time of final rasping of the femur. Additionally, the G-guide was utilised at the time of final rasp insertion. In intraoperative AT assessment using this instrument, a correction was required considering the discrepancy between the perpendicular to the posterior condylar axis and the longitudinal axis of the lower leg. The angle of discrepancy between posterior condylar line and femoral trans-epicondyler axis needs to be taken into consideration. Therefore, correction by the angle between the trans-epicondylar and posterior condylar lines (correction angle) was required for each patient when the intraoperative AT as measured by the G-guide. Therefore, the correction angle should be added to the AT value obtained from the G-guide for comparison with postoperative value measured with Zed Hip.Purpose
Method
We investigated the characteristics of patients
who achieved Japanese-style deep flexion (seiza-sitting) after total knee
replacement (TKR) and measured three-dimensional positioning and
the contact positions of the femoral and tibial components. Seiza-sitting
was achieved after surgery by 23 patients (29 knees) of a series
of 463 TKRs in 341 patients. Pre-operatively most of these patients
were capable of seiza-sitting, had a lower body mass index and a favourable
attitude towards the Japanese lifestyle (27 of 29 knees). According
to two-/three-dimensional image registration analysis in the seiza-sitting
position, flexion, varus and internal rotation angles of the tibial
component relative to the femoral component had means of 148° ( Cite this article:
We reviewed retrospectively the MRI examinations of 108 knees of 80 children to identify the prevalence of a high signal in the menisci of those without symptoms. There were 51 boys and 29 girls with a mean age of 12.2 years (8 to 15). The prevalence of a high signal within the menisci was 66%, significantly higher than that in an adult group (29%). The prevalence decreased with age: grade-2 and grade-3 changes were observed in 80% of menisci at ten years of age, in 65% at 13 years and in 35% at 15 years. The prevalence of high signals also decreased with increased skeletal maturity at the knee. We emphasise the importance of awareness of the high prevalence of a high signal intensity in the menisci of children, especially in early adolescence.
