To measure for evidence of early subsidence of Accolade tapered uncemented femoral stems. To quantify any subsidence and to identify factors which may predispose to this. A retrospective audit of patients who have received Accolade stem total hip joint replacement in Hawkes Bay Hospital from October 2003 to October 2004. Post operative and follow up x rays (within one year of surgery) were reviewed and position of femoral component in the femur was measured and adjusted for magnification and angulation. Thirty-eight patients were identified. Patients age averaged 66 years old (44 – 82yo). Results show an mean subsidence of 2.8mm with a range of 0 – 13mm. There is evidence of early subsidence of Accolade femoral stems. In cases of large subsidence under sizing of the femoral component was identified as the most significant contributing factor

Purpose. Accolade TMZF® has the wedged taper shape and is fixed at the middle part. We testified the short term result of Accolade® and investigated the factor of subsidence. Materials and Methods. We treated 21 hips in 20 patients (6 males and 15 females) with Accolade stem. The mean age was 61.2 years old (40–79 years old). The mean follow-up period was 11.1 months (6–23 months), and those within 5 months after operation were excluded. We measured the width of the stem and the canal of femur at the level of the upper and the lower end of lesser trochanter, and 1 cm above the tip of the stem at operation and at the last follow-up, then calculated the canal fill ratios. We also measured the distance between the tip of the stem and the proximal end of greater trochanter, then calibrated it by directly sizing the acetabular component. The value that subtracted the distance at the last follow-up from the distance at operation meant subsidence. We performed multiple regression study about weight and the canal fill ratio of stem at the level of lower end of lesser trochanter. Results. The mean subsidence of the stem was 1.24 mm (0∼4.50 mm). The patients with 2 mm or more subsidence were four, and the patients with 1 mm or less subsidence were ten. There were no significant differences in weight and the canal fill ratio at the level of lower end of lesser trochanter, but the canal fill ratio of the stem tended to negatively correlate with subsidence. Discussions and conclusions. Some authors reported the most important factors in predicting a failure of osteointegration were canal fill at the mid-third of the stem, canal fill at the distal-third of the stem, and canal flare index. Others reported large stem size was associated with subsidence. Our result showed the canal fill ratio at the level of lower end of lesser trochanter is associated with subsidence. Besides, Accolade® tended to result in more severe resorption of the proximal femur and lack of osteointegration. Accolade® had a good result in the short term evaluation, but we should observe the subsidence carefully because the proximal femur cortex inclines to resorption and the osteointegration doesn't ocuur

Introduction. The Accolade II taper stem incorporates design features which maximize proximal stem fit and bone contact and avoids more distal taper engagement which has been shown to be problematic. RSA was used in this study to analyze stem micromotion to 2 years post-surgery, providing an indication of long-term fixation. Pain, function and health-related quality of life were also compared before and after total hip arthroplasty (THA.). Method. This prospective, single centre case-series enrolled 35 patients into Parts A and B. The first 5 subjects were recruited to Part A of the study (learning curve), the subsequent 30 patients to part B. Radiopaque tantalum beads were inserted intra-operatively into each patient, with RSA radiographs taken immediately post-operatively, and at 3, 6, 12 and 24 months. These radiographs were digitized to DICOM file format and exported, allowing for independent analysis using the UmRSA system. Three Patient Reported Outcome Measurements; WOMAC, EQ-5D-3L and VAS pain were collected pre-operatively and at 6, 12 and 24 month intervals for all patients. Results. A total of 33 patients completed the study, with 1 patient from Part A lost to follow up and 1 patient from part B withdrawing voluntarily. The 4 completed patients from part A of the study did not have RSA X-rays analysed since Part A was included for surgeon training purposes only. Hence RSA X-rays at the 2 year timepoint for 29 completed Part B patients were compared to immediate post-op RSA X-rays. The Average Maximum Total Point Motion (MTPM) of the Accolade II femoral stem was 0.764mm (SD +/− 0.340), with a clinical precision (defined as the standard deviation of double RSA examinations taken during the post-operative interval) of +/− 0.195mm. Additionally, the mean distal, medial and posterior migrations for the 29 patients at 24 months were all less than 0.1mm. When comparing with the literature, these MTPM values show less than average stem migration. A systematic review conducted by de Vries et al (2014) recorded 2 year MTPM values between 0.66 and 2.73mm for clinically successful uncemented collarless stems, with an average of 1.50mm. The average WOMAC and VAS pain scores for 33 completed patients from parts A and B demonstrated decreased pain and functional limitations at 24 months when compared with pre-operative PROM results. In addition, average UK Time Trade-Off scores calculated from the EQ-5D-3L improved from 0.47 (SD +/− 0.29) pre-operatively to 0.86 (SD +/− 0.27) at 24 months, equating to improved health-related quality of life for all patients. Conclusions. The mean MTPM from this study falls well below the average for uncemented collarless stems suggested by de Vries et al (2014). This, together with the negligible distal stem migration, affirms excellent immediate stability of the Accolade II design. These RSA results imply successful biologic fixation and a high survival rate can be expected with the Accolade II stem

Over the past ten years we have seen a move to less invasive surgical approaches and simplification of OR procedures; hence, there has been a renewed interest in the use of rectangular wedge-taper design hip stems. I present a personal series of over five hundred Accolade (Stryker) stems with a high (6%) early failure rate. Cases are drawn from a personal database. These patients presented with either pain or difficulty with stair-climbing. Several remain asymptomatic, but radiographs are early identical in all cases. Impressive radio-lucent and sclerotic lines are seen on the lateral radiograph in Gruen zones VIII and XIV at between three and six months, and later appear in Gruen I. Most occurred in type A or AA bone. These failures are interesting as they are due to rotational loosening, not axial subsidence. To date, 6 of 12 have been revised, all showing complete lack of ingrowth to proximal porous coating. Rectangular wedge-taper design stems have enjoyed high success rates in several published series. However, the author believes that the use of this stem in Type A or AA bone leads to preferential distal (diaphyseal) taper engagement, which negates proximal (meta-diaphyseal) taper engagement, and predisposes the stem to rotational micromotion, failure of ingrowth, and subsequent loosening. To our knowledge, this is the first paper to recognise this mode of failure. The authors strongly believe stems of this type should be used with caution in males with type A or AA bone

Purpose. The ultimate goal in total hip arthroplasty is not only to relieve the pain but also to restore original hip joint biomechanics. The average femoral neck-shaft angle(FNSA) in Korean tend to have more varus pattern. Since most of conventional femoral stems have relatively high, single, fixed neck shaft angle, it's not easy to restore vertical and horizontal offset exactly especially in Korean people. This study demonstrates the advantages of dual offset(especially high-offset) stem for restoring original biomechanics of hip joint during the total hip arthroplasty in Korean. Materials and Methods. 180 hips of 155 patients who underwent total hip arthroplasty using one of the standard(132°) or extended(127°) offset Accolade cementless stems were evaluated retrospectively. Offset of stem was chosen according to the patient's own FNSA in preoperative templating. In a morphometric study, neck-shaft angle of proximal femur, vertical offset and horizontal offset, abductor moment arm were measured on preoperative and postoperative both hip AP radiographs and the differences and correlation of each parameters, between operated hip and original non-operated hip which had no deformity (preoperative ipsilateral or postoperative contralateral hip), were analyzed. Results. The standard stems were used in 34 hips and extended offset stems were used in 146 hips. The FNSA of non-operated hip was an average of 129.8°(127.2°□135.8°) in standard group and mean 125.4°(122.7°□129.9°) in extended offset group. The FNSA of operated hip was an average of 131.6° and 127.1° in each group. In the statistical analysis, there was no significant difference of mean horizontal and abductor moment arm between operated hip and non-operated hip in both groups and the restoration of horizontal offset and abductor moment arm showed(p=0.217, p=0.093) significant positive correlation(R=0.870, R=0.851) to the original value. However, vertical offset was increased an average of 1.4mm in operated hip and there was statistical significance. Restoration of vertical offset showed positive correlation to original value (R=0.845). Conclusion. Dual- or multi-offset stem, especially extended offset stem can provide easy restoration of hip biomechanics and soft tissue tension without significant alteration of leg length especially in Korean with more varus femoral neck compared to Caucacian. Precise radiographic measurements of original hip and application of proper-offset stem should be taken in order to restore ideal hip biomechanics successfully and easily. A use of a proper offset stem can afford to enhance joint stability and implant longevity by improving soft-tissue tension and reducing resultant force, and it will guarantee a successful results after total hip arthroplasty in the aspect of function and longevity

The purposes of this study were to report the accuracy of stem anteversion for Exeter cemented stems with the Mako hip enhanced mode and to compare it to Accolade cementless stems. We reviewed the data of 25 hips in 20 patients who underwent THA through the posterior approach with Exeter stems and 25 hips in 19 patients with Accolade stems were matched for age, gender, height, weight, disease, and approaches. There was no difference in the target stem anteversion (20°–30°) between the groups. Two weeks after surgery, CT images were taken to measure stem anteversion. The difference in stem anteversion between the plan and the postoperative CT measurements was 1.2° ± 3.8° (SD) on average with cemented stems and 4.2° ± 4.2° with cementless stems, respectively (P <0.05). The difference in stem anteversion between the intraoperative measurements and the postoperative CT measurements was 0.75° ± 1.8° with Exeter stems and 2.2° ± 2.3° with Accolade stems, respectively (P <0.05). This study demonstrated a high precision of anteversion for Exeter cemented stems with the Mako enhanced mode and its clinical accuracy was better with the cemented stems than that with the cementless stems. Although intraoperative stem anteversion measurements with the Mako system were more accurate with the cemented stems than that with the cementless stem, the difference was about 1° and the accuracy of intra-operative anteversion measurements was quite high even with the cementless stems. The smaller difference in stem anteversion between the plan and postoperative measurements with the cemented stems suggested that stem anteversion control was easier with cemented stems under the Mako enhanced mode than that with cementless stems. Intraoperative stem anteversion measurement with Mako total hip enhanced mode was accurate and it was useful in controlling cemented stem anteversion to the target angle

Objectives. In total hip arthroplasty (THA), the cementless, tapered-wedge stem design contributes to achieving initial stability and providing optimal load transfer in the proximal femur. However, loading conditions on the femur following THA are also influenced by femoral structure. Therefore, we determined the effects of tapered-wedge stems on the load distribution of the femur using subject-specific finite element models of femurs with various canal shapes. Patients and Methods. We studied 20 femurs, including seven champagne flute-type femurs, five stovepipe-type femurs, and eight intermediate-type femurs, in patients who had undergone cementless THA using the Accolade TMZF stem at our institution. Subject–specific finite element (FE) models of pre- and post-operative femurs with stems were constructed and used to perform FE analyses (FEAs) to simulate single-leg stance. FEA predictions were compared with changes in bone mineral density (BMD) measured for each patient during the first post-operative year. Results. Stovepipe models implanted with large-size stems had significantly lower equivalent stress on the proximal-medial area of the femur compared with champagne-flute and intermediate models, with a significant loss of BMD in the corresponding area at one year post-operatively. Conclusions. The stovepipe femurs required a large-size stem to obtain an optimal fit of the stem. The FEA result and post-operative BMD change of the femur suggest that the combination of a large-size Accolade TMZF stem and stovepipe femur may be associated with proximal stress shielding. Cite this article: M. Oba, Y. Inaba, N. Kobayashi, H. Ike, T. Tezuka, T. Saito. Effect of femoral canal shape on mechanical stress distribution and adaptive bone remodelling around a cementless tapered-wedge stem. Bone Joint Res 2016;5:362–369. DOI: 10.1302/2046-3758.59.2000525

Purpose. Primary uncemented total hip arthroplasty is the fixation of choice for most patients undergoing hip replacement in North America. Initial stem stability will be detected by the fit and fill of the implant to the bone as well as the overall stem geometry as it relates to its mechanical stability. This study aims to determine the geometric and structural parameters of common cementless tapered femoral stems to better understand their early clinical performance with respect to bony fixation. Method. Templates for six proximally coated tapered uncemented femoral stems: Accolade (Stryker), Profemur (Wright), Taperloc (Biomet), M/L Taper (Zimmer), Anthology (Smith-Nephew) and Trilock (Depuy) were scanned and saved as images on a PC. Stem sizes were assigned according to AP plane width measurements taken at the most lateral implant shoulder, and images analyzed using ImageJ (US National Institutes of Health). Measurements were made of stem length, and at various locations, the width and thickness of the stem. Coronal plane stiffness was calculated according to beam theory, assuming an elastic modulus of 114 GPa for the Profemur, Taperloc M/L Taper, Anthology and Trilock stems. The Accolade stem has a modulus of 85.5 GPa. due to TMZF alloy which is 25% more flexible. Stem thickness and taper ratios were calculated as a measure of lateral vs. AP fill of the femur. All measurements were plotted as manufacturer-specific curves relative to stem width. Results. Stiffness-size curves between different stem designs were similar, although overall flexibility varied markedly between manufacturers. Stem stiffness varied over a range of up to 30% (3.1 to 4.3 kNm2) depending on width, with the greatest range in larger stem sizes. The most flexible stems, in order of increasing stiffness, were: Accolade, Trilock, and Anthology. The Taperloc, M/L Taper, and Profemur designs were stiffest and approximately equivalent at all widths. The greatest stem flexibility variation occurred at the implants lateral shoulder, where the Accolade design exhibited a 22% lower stiffness than the next closest design. Conclusion. Stem geometry differs significantly amongst commercially available tapered blade type stems designs which may have significant implications for overall stem stiffness. The Accolade stem exhibits greater relative flexibility in its larger sizes. These findings provide some insight into the clinical reports of a high percentage of stem subsidence with the larger size Accolade. Our data suggest this may be due to lower structural stiffness and greater micromotion inherent to this stem design, which in turn may inhibit early implant osteointegration

Introduction. Modern cementless press fit stems rely on early fixation and stability for osteointegration and longterm success with early migration increasing the risk of failure. The Ein Bild Roentegen Analyse Femoral Component Analysis (EBRA-FCA) methods allow accurate measurement of femoral stem subsidence without the need for Tantalum markers. The degree of subsidence of femoral stems in the first two years has been shown to be highly predictive of failure when using the cut off value of 1.5 mm. We aimed to measure the early migration pattern of a titanium alloy, tapered, plasma and hydroxyapatite coated femoral stem and any factors associated with subsidence. Methods. Between January 2005-June 2007, 387 Accolade cementless femoral stems (Stryker, Allendale NJ) were implanted at our institution. Seventy-seven had a minimum of two years post operative follow up and a complete set of pre and postoperative radiographs for analysis. Our group inlcuded 45 females with a mean age of 71.4 years, and 32 males with a mean age of 68.5 years. The primary diagnosis was degenerative osteoarthritis in 71 patients, avascular necrosis in two, and post fracture in four patients. The average BMI was 27.1. We measured the canal index to assess bone quality and the canal calcar index to assess the proximal femoral morphology. Immediate postoperative radiographs were assessed for canal fill of the prosthesis and implantation varus/valgus angles. The EBRA-FCA software was used to obtain migration curves for each stem. Results. The mean follow up was 29.3months (24–48). The mean canal index was 0.55 (0.36–0.68) with a mean canal calcar index of 0.54 (0.39–0.79). The average canal fill index at the midpoint of the stem was <0.8 in 37 stems and >80 in 40 stems. The average subsidence at 24 months was 2 mm and this had risen to 2.4 mm by 36 months postoperatively. When analysed using a Kaplan Meier curve using 1.5 mm as an end point we found a survivorship of 63.4% (52.3–74.5) at 24 months and this had worsened to 41.6% (26.6–56.5) by 36 months. Multivariate and univariate regression analysis of measured variables did not reveal any significant hazard for any factor other than the larger stem sizes doing worse. Discussion. Although several cementless tapered stem designs have had an excellent track record, our migration analysis of the Accolade stem is somewhat concerning. Thirty three percent of stems had reached the 1.5 mm subsidence point by two years. This is of concern as work has previously shown this to predict failure of stems with aseptic loosening at ten years with an accuracy of 79%. If these stems go on to fail at the predicted rate this would represent an unacceptably high level of failure. Our data raises serious concerns about the overall clinical performance of this stem design due to poor initial stability and integration

Purpose: We aimed to measure the early migration pattern of a titanium alloy, tapered, plasma and hydroxyapatite coated femoral stem and any factors associated with subsidence. Method: Between January 2005–June 2007, 387 Accolade cementless femoral stems (Stryker, Allendale NJ) were implanted at our institution. Seventy-seven had a minimum of two years post operative follow up and a complete set of pre and postoperative radiographs for analysis. Our group inlcuded 45 females with a mean age of 71.4 years, and 32 males with a mean age of 68.5 years. The primary diagnosis was degenerative osteoarthritis in 71 patients, avascular necrosis in two, and post fracture in four patients. The average BMI was 27.1. We measured the canal index to assess bone quality and the canal calcar index to assess the proximal femoral morphology. Immediate postoperative radiographs were assessed for canal fill of the prosthesis and implantation varus/valgus angles. The EBRA-FCA software was used to obtain migration curves for each stem. Best fit curve of subsidence over time was calculated and the data was analysed using a Kaplan Meier survivorship with 1.5 mm of subsidence as an endpoint. We then performed a multivariate and univariate regression analysis for predictors of subsidence. Results: The mean follow up was 29.3months (24–48). The mean canal index was 0.55 (0.36–0.68) with a mean canal calcar index of 0.54 (0.39–0.79). The average canal fill index at the midpoint of the stem was 80 in 40 stems. A total of 414 radiographs were analysed for the EBRA measurements. Of these 21 (5%) were discarded by the software as they did not meet the criteria for comparability. This led to the exclusion of seven patients, leaving the final study group of 77. All remaining patients had a minimum of four radiographs with an average of 4.6 for analysis. The average subsidence at 24 months was 2 mm and this had risen to 2.4 mm by 36 months postoperatively. When analysed using a Kaplan Meier curve using 1.5 mm as an end point we found a survivorship of 63.4% (52.3–74.5) at 24 months and this had worsened to 41.6% (26.6–56.5) by 36 months. Multivariate and univariate regression analysis of measured variables did not reveal any significant hazard for any factor other than the larger stem sizes doing worse. Conclusion: Although several cementless tapered stem designs have had an excellent track record, our migration analysis of the Accolade stem is somewhat concerning. Thirty three percent of stems had reached the 1.5 mm subsidence point by two years. This is of concern as work has previously shown this to predict failure of stems with aseptic loosening at ten years with an accuracy of 79%. If these stems go on to fail at the predicted rate this would represent an unacceptably high level of failure. Our data raises serious concerns about the overall clinical performance of this stem design due to poor initial stability and integration

Aims

This study was designed to develop a model for predicting bone mineral density (BMD) loss of the femur after total hip arthroplasty (THA) using artificial intelligence (AI), and to identify factors that influence the prediction. Additionally, we virtually examined the efficacy of administration of bisphosphonate for cases with severe BMD loss based on the predictive model.

Introduction. Pelvic posterior tilt change (PPTC) after THA is caused by release of joint contracture and degenerative lumbar kyphosis. PPTC increases cup anteversion and inclination and results in a risk of prosthesis impingement (PI) and edge loading (EL). There was reportedly no component orientation of fixed bearing which can avoid PI and EL against 20°PPTC. However, dual mobility bearing (DM) has been reported to have a large oscillation angle and potential to withstand EL without increasing polyethylene (PE) wear against high cup inclination such as 60∼65°. Objective. The purpose of this study was to investigate the optimal orientation of DM-THA for avoiding PI and EL against postoperative 20°PPTC. Methods. Our study was performed with computer tomography -based three-dimensional simulation software (ZedHip. LEXI co. Japan). The CT data of hip was derived from asian typical woman with normal hips. Used prosthesises were 50mm cup and 42mm outer head of modular dual mobility system and Accolade II 127°(stryker). Femoral coordinate system was retrocondylar plane with z-axis from trochanteric fossa to intercondylar notch. Cup orientation was described as anatomical definition. The safe zone was calculated by the required hip range of motion which was defined as 130°flexion, 40°extension, 30°external rotation, and 50°internal rotation with 90°flexion and the maximum inclination of DM cup which was 60°in consideration of withstanding EL. Cup orientations withstanding 20°PPTC were defined as the primary cup orientation which changes consistently within the safe zone with the match of 20°PPTC. And among them cup orientation with lowest inclination was defined as the optimal cup orientation. result. The optimal orientations could be identified only within stem anteversion from 15°to 40°. The relationship between the optimal cup orientation and stem anteversion could be automatically identified. The correlation between stem anteversion and cup anteversion was linearly distributed and could be expressed as an approximated line of the formula that (stem anteversion)+(cup anteversion)=36.8. And likewise the relationship between stem anteversion and cup inclination was curved-linerly distributed and could be expressed as an approximated curved line of the formula that (cup inclination)=0.04(stem anteversion). 2. 2.18(stem anteversion)+74.8. Cup orientation calculated by the Widmer's combined anteversion theory is easily deviated from the safe zone by PPTC. The optimal cup orientation calculated in this study could be set more inclination and retroversion than it calculated by the Widmer's theory in contribution of large oscillation angle and admissibility of high inclination cup setting of DM. Therefore it could be possible to withstand 20°PPTC. Conclusion. Performing THA with considering postoperative PPTC is necessary for good long term outcome without dislocation and PE wear. The solution for 20°PPTC after THA is to apply dual mobility bearing and the formula of combined orientation theory calculated in this study

The number of hip arthroplasty procedures has steadily increased in the United States over the last decade [Wolford, et. al, 2015]. This trend will continue as this treatment is the most effective approach in relieving pain, improving mobility, reducing fall risk and improving the quality of life in patients with end-stage osteoarthritis. The effectiveness of recovery can be impacted by factors such as access to postoperative physical therapy regimens. During the recovery period, it is important for therapists to be guided in their therapeutic decision making by accurate data concerning the patient's performance on a variety of measures. This project is designed to map the gait recovery curves of individuals who have undergone unilateral hip arthroplasty. To date, eight individuals (4 females, mean age 64.9, SD 11.1) have participated in the study. Five of the patients were treated by traditional press-fit Accolade II implants (Stryker, Mahwah, NJ USA) through a direct anterior approach THA and the other three has been treated by using DAA THA and using neck preserving Minihip. TM. short stem implant (Corin Ltd., Cirencester, UK). Each participant walked on an instrumented treadmill as a self-selected speed for three minutes pre-surgery. Post-surgery data collections occurred at three and six weeks, and three and six months and employed the same treadmill speed as used prior to surgery. Bilateral lower limb kinematic data was collected with a 12 camera motion capture system Vicon® (Oxford Metrics, Oxford, UK) using reflective markers attached to the hip, knee, ankle, heel and toe. Force plates embedded in the treadmill provided kinetic data that aided in the detection of heel strike and toe off. The temporal features associated with gait, including stride, stance time and double support time were obtained for both the surgical and non-surgical limbs and were used to assess changes in performance during the recovery period. The stance and double support data were also converted to a percentage of stance values which provide additional insights into gait control strategies. Repeated measure MANOVAs were used to evaluate any potential differences in the variables either between limbs or over time. Results from the statistical testing revealed that there were no significant differences between the two limbs for either stride or stance time. This was expected since global asymmetrical gait would have led to the participants veer off of the treadmill. There was a main effect of ‘Time’ for both stride and stance times. Post hoc testing indicated that the 6-month post-surgery measures were significantly reduced when compared to the Pre-surgery and 3-week post-surgery measures. Similarly, there were no significant differences in double support times between the two legs but there was a main effect for time. Post hoc testing revealed that the 6-month post-surgery double support time was significantly less than the Pre-surgery and 3-week post-surgery measures. These significant changes clearly indicate that surgery is effective in improving gait parameters. Moreover, clinicians may want to consider assessing double support time as this measure is a particularly robust indicator of the effectiveness of unilateral hip arthroplasty

Hip arthroplasty is commonly used as the final treatment approach for patients experiencing end-stage osteoarthritis. The number of these patients needing this treatment is expected to grow significantly by year 2030 to more than 572000 patients [Kurtz et al., 2007]. One of the important outcomes of hip arthroplasty is to improve patients' functions postoperatively. The evaluation of walking can provide a wealth of information regarding the efficiency of this treatment in improving a patient's mobility. Assessing the kinematic features of gait collected with a motion capture system combined with the aid of a motor-driven treadmill provides the advantage of enabling the evaluator to collect precise information about a large number of strides in a short period of time. Body segment kinematics (i.e. joint motion) are most often represented in the form of time series data with the abscissa (X axis) representing time and the ordinate (y axis) representing the motion of a particular joint. Although a great deal of information can be gained from the analyses of time series data, non-linear analyses tools can provide an additional and important dimension to a clinician's assessment of gait recovery. In this study eight patients (4 females, mean age 64.9, SD 11.1) have currently been assessed after unilateral hip arthroplasty. All surgeries were conducted by direct anterior approach by using two different approaches; three of the patients were treated by bone preservation technique and received Minihip short stem implant (Corin Ltd., Cirencester, UK) and five were treated by using a press fit stem implant Accolade II (Stryker, Mahwah, NJ USA). Patients performed a single three-minute trial of walking on a motor-driven treadmill at a self-selected pace. Using a 12 camera system, bilateral lower limb joint motion was collected prior to the surgery, at three and six weeks and at three and 6 months after the surgery. Depending upon the patient's preferred walking pace; between 40 and 45 strides were collected during each trial. Kinematic data obtained from force plates embedded in the treadmill were used to identify the heel strike and toe off events for each stride. After time normalizing the each of the joint angles (i.e. hip, knee, ankle) for each stride to 100 data points the data were then amplitude normalized to the initial point of the pre-surgery data. The non-linear tools of angle-angle and phase plane were used to explore relationships that are not readily apparent with linear wave form analyses. Angle-angle diagrams between a variety of joints angles both within a single limb or bilaterally enabled us to explore segmental coordination patterns and how they changed over the six months after surgery. Phase plane analyses included comparing joint motion relative to the velocity of that motion. This technique provided insights into the nature of the control of the joint. The additional information that results from the use of non-linear analyses provides an additional dimension of that can aide the clinician in understanding the recovery curve. This additional insight can be used to guide therapeutic decision making

Purpose. The purpose of this study was to evaluate and compare the clinical, radiological outcomes of the group of patients with distal femoral cortical hypertrophy (DFCH) and without DFCH after hip arthroplasty using a cementless double tapered femoral stem and to analyze a correlation between patients factors and DFCH. Materials and Methods. Four hundreds four patients (437 hips) who underwent total hip arthroplasty (n = 293) or hemiarthroplasty (n = 144) using a Accolade TMZF femoral stem between Jun 2006 and March 2012 and were follow up period more than 24 months after surgery were enrolled in this study. They were divided into 2 groups, the one group (n = 27) included patients with DFCH, and the other group (n = 410) included patients without DFCH. The mean follow up period was 54.5 months (range, 24 to 85 months) and 56.2 months (range, 24 to 92 months) for patients with DFCH and without DFCH. Results. The mean HHS, VAS signiï¬cantly improved from 61.4 and 5.5 preoperatively to 95.9 and 1.0 at the ï¬nal follow-up, respectively (P< .001), in the DFCH group and from 57.8 and 4.5 to 91.6 and 0.6 respectively (P< .001), in the control group. There were no signiï¬cant differences between the 2 groups (P> .05). Incidence of the thigh pain in the DFCH group (18.5%) was significantly higher than the control group (2.2%) (P< .001). The mean canal flare index (CFI) and subsidence was 3.71 (range, 2.61 to 5.78) and 1.5 mm (range, 0.1 to 6.1mm) for the DFCH group, 3.30 (range, 1.31 to 5.61) and 3.4 mm (range, 0.33 to 14.9 mm) for the control group. There were significantly differences between 2 groups (p< .002, < .001). The DFCH was significantly correlated with thigh pain and subsidence (p= .001; OR, 11.194; CI, 3.434 to 36.498 for thigh pain, p= .001; OR, 0.080; CI, 0.032 to 0.198 for subsidence), but not with sex. The incidence of DFCH increased significantly with increasing CFI and decreasing age (P= .043; OR, 1.828; CI, 1.018 to 3.280 for CFI; P= .015; OR, 0.968; CI, 0.944 to 0.994 for age). All the femoral stems showed stable fixation and there was no osteolysis or loosening. Conclusion. The DFCH occurs in 6.2% after hip arthroplasties using a double tapered femoral stem. The DFCH group showed less incidence of vertical subsidence, more younger and larger CFI. Difficult over tight placement of femoral stem to the distal femur results on DFCH, as well as thigh pain in some cases. However, there was no influence on clinical outcomes and femoral stem instability, bony fixation

Aims

Computer-assisted 3D preoperative planning software has the potential to improve postoperative stability in total hip arthroplasty (THA). Commonly, preoperative protocols simulate two functional positions (standing and relaxed sitting) but do not consider other common positions that may increase postoperative impingement and possible dislocation. This study investigates the feasibility of simulating commonly encountered positions, and positions with an increased risk of impingement, to lower postoperative impingement risk in a CT-based 3D model.

Introduction. One of the most common complications of ceramic on ceramic hip replacement is squeaking. The association of Accolade stem and Trident acetabular system has been reported to have squeaking incidence of up to 35,6%. There is doubt if this phenomenon occurs due to: the stem titanium alloy, the V40 femoral neck, the recessed liner of the trident cup or even the mal-seating of the trident insert on the cup. Objectives. Primary: The purpose of the present study was to determine the incidence of squeaking in association with the use of Exeter stem and Trident ceramic acetabular system. Secondary: Analysis of the correlation of the cup abduction angle and squeaking. Methods. During the period from March 2004 to December 2008, two surgeons performed 87 total hip arthroplasties in 77 patients with use of a ceramic-on-ceramic bearing (Exeter stem, alumina head, Trident ceramic acetabular system). Seventy six patients (86 THA) were available for review after at least 18 months follow-up. The incidence of squeaking and other noises was analyzed. Cup abduction angle was measured. The Pearson correlation coefficient was used to determine if a correlation existed between the cup abduction angle and squeaking. Results. The incidence of squeaking was 2,63% (2 patients). Both patients reported a “click” noise in hyperextension of the hip. The mean abduction angle was 44 degress (35–60), and 48 degrees (46 and 50) on the squeaking group. There was no statistically significant difference in the in the mean cup inclination between squeaky and quiet hips. Conclusion. The incidence of squeaking in association with the use of Exeter stem and Trident ceramic acetabular system was 2,63%. There was no correlation of the cup abduction angle and squeaking

Introduction. Uncemented components necessitate accurate intraoperative assessment of size to avoid complications such as calcar fracture and subsidence whilst maintaining bone stock on the acetabular side. Potential problems can be anticipated pre-operatively with the use of a templating system. We proposed that pre-operative digital templating could accurately assess femoral and acetabular component size. Methods. Pre-operative templating data from 100 consecutive patients who received uncemented implants (Trident cup, Accolade stem) and who were operated on by the senior author were included in the study. Calibrated pelvis anterior-posterior X-rays were templated with Orthoview™ software. Demographic data, templating data (stem and cup size, femoral neck cut), operative records (actual stem and cup size, head size) and post-operative data (femoral stem alignment, radiographic leg length, acetabular cup abduction angle) were collected. Results. There were 51 males and 49 females with a mean age of 60 yrs (SD = 7.3 yrs). Seventy five percent of stems were templated to within 0.5 size and 98% to within 1 size. A total of 80% of cups were templated to within 2mm and 98% to within 4mm. 62% of head length was accurately template. Seven patients were converted from a templated 132° to a 127° femoral prosthesis neck angle. The acetabulum cup abduction angle was 45° (SD = 4.81) and stem alignment was 1.5° (SD = 1.13). The mean lower limb length discrepancy was +0.05mm (SD = 5.1 mm) post-operatively. Conclusion. Digital templating is a accurate method of assessing femoral and acetabular component sizes. This allows surgeons to foresee potential problems and also recognize an intra-operative error when a large discrepancy exists between a trial component and the templated size

Introduction. The purpose of this study was to evaluate the functional and radiographical results in patients younger than 30 years who underwent cementless third generation ceramic-on-ceramic total hip arthroplasty for osteonecrosis of the femoral head. Methods. Forty one patients (55 hips) who underwent total hip arthroplasty with third generation ceramic-on-ceramic bearings for osteonecrosis of the femoral head with a minimum 4-year follow-up were included in this study. There were 26 men and 15 women who had a mean age of 26 years (range, 16 to 29 years). The average duration of follow-up was 6 years (range, 4 to 7 years). All surgeries were done by a single hip surgeon and third generation ceramic-on-ceramic articulations were used. Securefit (Stryker) acetabular components were used in 46 hips and Duraloc (Depuy) in 9 hips. Accolade (Stryker) femoral stems were used in 33 hips, cone prosthesis (Zimmer) in 18 hips and CLS (Zimmer) in 4 hips. Functional results were measured by Harris hip (HHS) and WOMAC scores. Radiographic evaluation was assessed for loosening and osteolysis according to Gruen and Delee and Charnley criteria. Results. The average HHS improved from 53 points (range, 24 to 59 points) pre-operatively to 95 points (range, 88 to 100 points) at last follow-up. WOMAC scores improved from 72 points (range, 50 to 98 points) to 25 points (range, 21 to 37 points). Thirty nine patients (51 hips) continued their normal occupation. There was no aseptic loosening, osteolysis, and no prosthesis had been revised. There was one patient who complained of continuous squeaking and two patients with Brooker grade I heterotopic ossification. There were no other major complications such as ceramic fracture. Conclusion. Total hip arthroplasty with third generation ceramic-on-ceramic bearings for osteonecrosis of the femoral head especially in active and young patients resulted in satisfactory clinical and radiological results at minimum 4 year follow-up. If long-term follow-up shows excellent results, then the age limit for total hip arthroplasty might be lowered

Introduction. The MITCH PCR is an anatomic, flexible, horse-shoe shaped acetabular component, with 2 polar fins. The rationale of the PCR cup design is to reproduce a near-physiological stress distribution in the bone adjacent to the prosthesis. The thin composite cup is designed to fuse and flex in harmony with the surrounding bony structure. Only the pathological acetabular cartilage and underlying subchondral bone of the horseshoe-shaped, load-bearing portion of the acetabular socket is replaced, thus preserving viable bone stock. The PCR is manufactured from injection moulded carbon fibre reinforced polyetheretherketone (PEEK), with a two layer outer surface comprising hydroxyapatite and plasma sprayed commercially pure titanium. It is implanted in conjunction with a large diameter low wear femoral head, producing a bearing that will generate minimal wear debris with relatively inert particles. Pre-clinical mechanical testing, finite element analysis and biocompatibility studies have been undertaken. FEA evaluation predicts preservation of host bone density in the load bearing segments. A pilot clinical study was completed on a proto-type version of the PCR cup (the “Cambridge” cup), achieving excellent 5 and 10 year results. Subjects and Methods. We report the three-year results from a two-centre, prospective clinical evaluation study of the MITCH PCR cup. Patient outcome has been assessed using standardised clinical and radiological examinations and validated questionnaires. The change in physical level of activity and quality of life has been assessed using the Oxford Hip Score, Harris Hip score and the EuroQol-5D score, at scheduled time-points. Serial radiographs have been analysed to monitor the fixation and stability of the components. Results and Conclusions. In total 25 PCR cups were implanted by 3 surgeons. There were 12 men and 13 women. The mean patient age at time of surgery was 67 years (range 57–74). An Accolade TMZF stem was used as the femoral component in 19 patients and an Exeter stem in 6. The mean Oxford Hip score improved from 19.8 pre-operatively to 45 at the latest follow-up. The mean Euroqol-5D score improved from 62.6 to 83.6 and the Harris Hip score improved from 49.9 to 90.6. Three adverse events were noted in 2 patients (2 chest infections and 1 deep vein thrombosis). One revision of the acetabular component was performed at 21 months for squeaking. This has been investigated and modification of the articular geometry has resolved the problem on in-vitro testing