Osteoporosis is common in total hip arthroplasty (THA) patients. It plays a substantial factor in the surgery’s outcome, and previous studies have revealed that pharmacological treatment for osteoporosis influences implant survival rate. The purpose of this study was to examine the prevalence of and treatment rates for osteoporosis prior to THA, and to explore differences in osteoporosis-related biomarkers between patients treated and untreated for osteoporosis. This single-centre retrospective study included 398 hip joints of patients who underwent THA. Using medical records, we examined preoperative bone mineral density measures of the hip and lumbar spine using dual energy X-ray absorptiometry (DXA) scans and the medications used to treat osteoporosis at the time of admission. We also assessed the following osteoporosis-related biomarkers: tartrate-resistant acid phosphatase 5b (TRACP-5b); total procollagen type 1 amino-terminal propeptide (total P1NP); intact parathyroid hormone; and homocysteine.Aims
Methods
The anatomic abnormalities are observed in developmental dysplasia of the hip (DDH) and it is challenging to perform the total hip arthroplasty (THA) for some DDH patients. If acetabular cup was placed at the original acetabular position in patients with high hip dislocation, it may be difficult to perform reduction of hip prosthesis because of soft tissue contracture. The procedures resolving this problem were to use femoral shortening osteotomy, or to place the acetabular cup at a higher cup position than the original hip center. Femoral shortening osteotomy has some concerns about its complicated procedure, time consuming, and risk of non-union. Conversely, implantation of the acetabular cup at the higher cup position may eliminate these shortcomings and this procedure is considered to be preferred if possible. However, the criteria of cases without femoral shortening osteotomy are not clear. In this study, we retrospectively analysed the clinical outcomes of patients performed THAs for high hip dislocation, and clarified the adaptation of THA with or without femoral shortening osteotomy. We included a total of 65 hip joints from 57 patients who underwent primary THA using Modulus stem for high hip dislocation from November 2007 to December 2015 at our institution. The mean follow up period was 5.2 years (2 – 10 years). The mean age at surgery was 65.4 years (Table 1). Thirty seven hips were classified as Crowe III, and twenty eight hips as Crowe IV based on Crowe classification. We classified patients into two groups based on the use of femoral osteotomy. Then, we compared the surgical time, blood loss, Japanese Orthopaedic Association (JOA) Score as clinical outcomes, preoperative position of the greater trochanter, the cup position, and complications between two groups. The position of the greater trochanter was measured the height of the tip of greater trochanter from the inter teardrop line. The cup center position was assessed by measuring the distance between the cup center and ipsilateral tear drop. Receiver operating characteristic (ROC) curves were plotted for deciding the cut-off value for the height of the greater trochanter. The cut-off value presented the maximum sensitivity and specificity was determined.Introduction
Methods
Patients with hip osteoarthritis have a substantial loss of muscular strength in the affected limb compared to the healthy limb preoperatively, but there is very little quantitative information available on preoperative muscle atrophy and degeneration and their influence on postoperative quality of life (QOL) and the risk of falls. The purpose of the present study were two folds; to assess muscle atrophy and degeneration of pelvis and thigh of patients with unilateral hip osteoarthritis using computed tomography (CT) and to evaluate their impacts on postoperative QOL and the risk of falls. We used preoperative CT data of 20 patients who underwent primary total hip arthroplasty. The following 17 muscles were segmented with our developed semi-automated segmentation method: iliacus, gluteus maximus, gluteus medius, gluteus minimus, rectus femoris, tensor facia lata, adductors, pectinus, piriformis, obturator externus, obturator internus, semimenbranosus, semitendinosus, vastus medialis and vastus lateralis/intermedius (Fig. 1). Volume and radiological density of each muscle were measured. The ratio of those of affected limb to healthy limb was calculated. At the latest follow-up, the WOMAC score was collected and a history of falls after surgery was asked. The average follow- up period was 6 years. Comparison of the volume and radiological density of each muscle between affected and healthy limbs was performed using the Wilcoxon signed rank test. Correlations between the volume and radiological density of each muscle and each score of the WOMAC were evaluated with Spearman's correlation coefficient. The volume and radiological density of each muscle between patients with and without a history of falls were compared using Mann-Whitney U test.Introduction
Methods
Although many distal fit and fill design cementless stems have shown a very good long term stable fixation, short proximal coated stems are recently increasing in their use with an expectation of less stress shielding and an ease of removal at revision surgery. We introduced an anatomic short stem made from titanium alloy with proximal plasma-spray titanium and hydroxyapatite coating (CentPillar, Stryker, Mahwah) in 2002. To evaluate a minimum 10-year outcome of the system in terms of fixation and stress shielding, we reviewed initial 100 consecutive cases operated by a single surgeon. There were 91 hips with osteoarthritis and 9 hips with osteonecrosis. There were 94 females and 6 males. Average age at operation was 58 years. The patients were followed up for an average of 11 years. Average JOA hip score improved significantly from 46.9 preoperatively to 96.7 at the final examination. There were no dislocation, or revision, or radiographic loosening. When we looked at the level of bone atrophy, 80% of cases showed no stress shielding below the lessor trochanter. We conclude that the CentPillar stem showed mild stress shielding due to short proximal bone ongrowth coating while keeping a long term good clinical score and radiographic stability.
Range of motion (ROM) simulation of the hip is useful to understand the maximum impingement free ROM in total hip arthroplasty (THA). In spite of a complex multi-directional movement of the hip in daily life, most of the previous reports have evaluated the ROM only in specific directions such as flexion-extension, abduction-adduction, and internal - external rotation at 0° or 90° of hip flexion. Therefore, we developed ROM simulation software (THA analyzer) to measure impingement free ROM in any positions of the hip. Recent designs of the hip implants give a wider ROM by increasing the head diameter and then, bone to bone impingement can be a ROM limit factor particularly in a combination of deep flexion, adduction and internal rotation of the hip. Therefore, the purpose of this study were to observe an individual variation in the pattern of the bone impingement ROM in normal hip bone models using this software, to classify the bone impingement ROM mapping types and to clarify the factors affecting the bone impingement type. The subjects were 15 normal hips of 15 patients. Three dimensional surface models of the pelvis and femur were reconstructed from Computer tomography (CT) images. We performed virtual hip implantation with the same center of rotation, femoral offset, and leg length as the original hips. Subsequently, we created the ROM mapping until bone impingement using THA analyzer. We measured the following factors influenced on the bone impingement map patterns; the neck shaft angle, the femoral offset, femoral anteversion, pelvic tilt, acetabular anteversion, sharp angle, and CE angle. These factors were compared between the two groups. Statistical analysis was performed with Mann-Whitney U test, and statistical significance was set at P<0.05.Introduction
Methods
The incidence of dislocation after total hip arthroplasty (THA) was reported to be 0.5 to 10% in primary THA and 10 to 25 % in revision THA. The main causes of instability after THA were reported to be implant malalignment and inappropriate soft tissue tension. However, there was no study about quantitative data of soft tissue tension of unstable THA. The purpose of this study is to clarify the features of soft tissue tension of unstable THA in comparison to stable THA. The subjects were 15 patients with 15 THAs who had developed recurrent dislocation after primary THA. Thirty four patients with 37 THAs who developed no dislocation for one year after surgery were recruited as a stable THA group. In both group, all THAs were performed through posterolateral approach. In order to assess the soft tissue tension of THA, we recorded antero-posterior radiographs of the hips while applying distal traction to the leg with traction forces of 20?, 30%, 40% of body weight (BW). The distance of separation of the head and the cup after traction was measured under correction of magnification. Nine of 15 THAs in the unstable THA group and 32 of 37 THAs in the stable THA group were unilateral involvement. In the hips with unilateral involvement, the femoral offset difference between the healthy hip and the reconstructed hip were evaluated. Statistical analysis was performed with χ2 testand Mann-Whitney U test, and statistical significance was set at P<0.05.Introduction
Methods
Three-dimensional (3D) templating based on computed tomography (CT) in total hip arthroplasty improves the accuracy of implant size. However, even when using 3D-CT preoperative planning, getting the concordance rate between planned and actual sizes to reach 100% is not easy. To increase the concordance rate, it is important to analyze the causes of mismatch; however, no such studies have been reported. This study had the following two purposes: to clarify the concordance rate in implant size between 3D-CT preoperative planning and actual size; and to analyze risk factors for mismatch. A single surgeon performed 149 THAs using Trident Cup and Centpillar Stem (Stryker) with CT-based navigation between September 2008 and August 2011. Minimal follow-up was 2 years. Patients with incomplete postoperative CT were excluded from this study. Based on these criteria, the study examined 124 hips in 111 patients (mean age, 60 years, mean BMI 23.2 kg/m2). The preoperative diagnosis was primary osteoarthritis in 8 hips, secondary osteoarthritis in 102 hips, osteonecrosis in 9 hips, rapidly destructive coxopathy in 4 hips and rheumatoid arthritis in 1 hip. We compared cup and stem sizes between preoperative planning and intraoperatively used components. Radiological evaluations were cortical index and canal flare index on preoperative X-rays. We evaluated preoperative planning and postoperative components for cup orientation, cup position, and stem alignment (anteversion, flexion and varus angle) on the CT-navigation system. Fixation of the stem was evaluated by X-ray radiography at 2 years postoperatively according to Engh's criteria. Statistical analysis was performed with the Mann-Whitney U test, and values of P<0.05 were considered statistically significant.Puropose
Materials and Methods
In these three years, many troubles have occurred in the arthroplasty by hip joint prostheses with metal on metal sliding surfaces. Anomalous reaction including a pseudotumor, which is supposed to be caused by the metal ions released from the implant surfaces, is the most serious problem for the patients1). This problem seriously confused us because there is the fact that ion release has not hardly occurred between a head and an acetabulum, where usual wear proceeds. The important clue was the stain that was sometimes found on the surfaces of the taper junction of retrieved prostheses. This stain has been generally estimated the evidence of the fretting corrosion. It has not been clarified why short range sliding enhances the corrosion, yet. In the present study, to elucidate this problem, we observed the behavior of the passive film of implant surfaces under the sliding conditions of fretting, which is presumed on the taper junction. In the present study, electric potential was measured as an indicator to assess the removal of the passive film of cobalt chromium (CoCr) alloy under the fretting conditions. A wear simulator (FPR-2100, RHESCA, Tokyo, Japan) was used for the testing apparatus with reciprocating motion. A Co-28Cr-6Mo alloy pin (Smith & Nepew, London, UK) specimen was 10 mm in diameter and abraded with the common material plate (Fig. 1). A load of 1 N was applied to a pin. The electronic potential between the pin and the Ag/AgCl reference electrode (HX-R5, HOKUTO DENKO, Tokyo, Japan) soaking in the PBS(−) as simulated biological fluid were measured using a high impedance electrometer (HE-104, HOKUTO DENKO, Tokyo, Japan) (Fig. 2). The sliding width was chosen 0.5–10 mm. The reciprocating cycle was chosen 0.5–2 Hz. The changes in the electronic potential of CoCr alloy were recorded during the sliding motion together with under the static conditions before and after the sliding motion.Introduction
Materials and Methods
