Clinical and radiological results of total hip arthroplasty (THA) using proximally coated single wedge (PSW) cementless stems are generally excellent. The geometry of cementless stems and the morphology of proximal femurs (Dorr types) provide optimal fit for primary stability and secondary biologic fixation. Because the geometry of PSW shape is designed to be engaged at the metaphysis, cementless PSW stem is not traditionally recommended to Dorr type C femurs with concerns of inadequate implant-host bone contact and the risk of femoral fracture. Nevertheless, previous studies on PSW cementless stems have not examined long-term survivorship according to Dorr types of femur. Paucity of a long-term comparative study makes it difficult to know whether the PSW stem plays a role in Dorr type C femurs or not. We postulated that the PSW stem could achieve stable fixation without increased risk of femoral fracture even in Dorr type C femurs, and demonstrate acceptable long-term results. The aim of this study was to investigate differences of clinical and radiological outcomes of THA using PSW stem according to proximal femoral geometry (Dorr types) in more than a 10-year follow-up. Three hundred and seven primary THA in 247 patients, which was performed with use of a single-designed PSW stem from 1997 to 2003 and was followed up for over 10 years, were included in this retrospective study. According to Dorr's criteria, 89 femora were classified as Type A, 156 as Type B, and 62 as Type C. The patients' mean age at operation was 43.2 years (range, 18.4 – 69.6 years). They were followed-up for an average of 13.2 years (the range, 10.0 – 17.3 years). All of the hips were evaluated clinically and radiologically with special attention to the occurrence of implant loosening and periprosthetic femoral fracture. The mean preoperative Harris hip score (50.4±20.6 points) improved significantly to 95.6±9.0 points at the final follow-ups. The improvements were observed regardless of Dorr types (p<0.001 in all 3 groups). The incidence of thigh pain (p=0.704) was not significantly different among groups. Implant survivorship was 100% in all 3 groups. None of the stems were loosened or revised. No significant differences were observed in osteolysis (p=0.492), pedestal formation (p=0.323), or cortical hypertrophy (p=0.169) among the groups [Fig. 1]. Radiolucent lines less than 2mm in thickness in Gruen zone 4 were observed more in Dorr type C femora than in Dorr type A or B (p=0.003) [Fig. 2]. Spot weld (p<0.001) and stress shielding (p=0.010) of proximal femur were more pronounced in Dorr C type femora than in type A or B [Fig. 3]. The prevalence of intraoperative (p=0.550) or postoperative (p=0.600) femoral fractures were not significantly different among the groups. From over a 10-year follow-up, the PSW stem provided excellent stem survivorship regardless of Dorr type with satisfactory outcomes. The remodeling process around the stem was more pronounced in Dorr type C femur. The present study shows that the PSW stem is a recommendable option for Dorr type C femur. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Clinical success of prostheses in joint arthroplasty is ultimately determined by survivorship and patient satisfaction. The purpose of this study was to compare (non-inferiority) a new morphometric designed stem for total hip arthroplasty (THA) against an established comparator. A prospective randomised multi-centre study of 144 primary cementless THA performed by nine experienced orthopaedic surgeons was completed (70 received a fully coated collarless tapered stem and 74 received a morphometric designed proximally coated tapered stem). PROMs and blood serum markers were assessed preoperatively and at intervals up to 2-years postoperatively. In addition, measures of femoral stem fit, fill and subsidence at 2-years post-operatively were measured from radiographs by three observers, with an intra-class correlation coefficient of 0.918. A mixed effects model was employed to compare the two prosthesis over the study period. A p-value <0.05 was considered statistically significant. Demographics, Dorr types and blood serum markers were similar between groups. Both stems demonstrated a significant improvement in PROMs between the pre- and post-operative measurements, with no difference at any timepoint (p > 0.05). The fully coated tapered collarless femoral stem had a non-significantly higher intra-operative femoral fracture rate (5.8% vs 1.4%, p = 0.24), with all patients treated with cable fixation and partial weight bearing. The mean subsidence at 2-years was 2.5mm +/- 2.3mm for the morphometric stem and 2.4mm +/- 1.8mm for the fully coated tapered collarless femoral stem (p = 0.879). There was one outlier in each group with increased subsidence (fully coated tapered collarless femoral stem 6.9mm, morphometric wedge stem 7.4mm), with both patients reporting thigh pain at 2 years. When compared with an established stem, the newer designed morphometric wedge stem performed well with comparable radiological and PROM outcomes at 2 year follow up. Continued follow-up is required for long term benchmarking

Clinical success of prostheses in joint arthroplasty is ultimately determined by survivorship and patient satisfaction. The purpose of this study was to compare (non-inferiority) a new morphometric designed stem for total hip arthroplasty (THA) against an established comparator. A prospective randomised multi-centre study of 144 primary cementless THA performed by nine experienced orthopaedic surgeons was completed (70 received a fully coated collarless tapered stem and 70 received a morphometric designed proximally coated tapered stem). PROMs and blood serum markers were assessed preoperatively and at intervals up to 2-years postoperatively. In addition, measures of femoral stem fit, fill and subsidence at 2-years post-operatively were measured from radiographs by three observers, with an intra-class correlation coefficient of 0.918. A mixed effects model was employed to compare the two prostheses over the study period. A p-value <0.05 was considered statistically significant. Demographics and Dorr types were similar between groups. Both stems demonstrated a significant improvement in PROMs between the pre- and post-operative measurements, with no difference at any timepoint (p > 0.05). The fully coated tapered collarless femoral stem had a non-significantly higher intra-operative femoral fracture rate (5.8% vs 1.4%, p = 0.24), with all patients treated with cable fixation and partial weight bearing. The mean subsidence at 2-years was 2.5mm +/- 2.3mm for the morphometric stem and 2.4mm +/- 1.8mm for the fully coated tapered collarless femoral stem (p = 0.879). There was one outlier in each group with increased subsidence (fully coated tapered collarless femoral stem 6.9mm, morphometric wedge stem 7.4mm), with both patients reporting thigh pain at 2 years. When compared with an established stem, the newer designed morphometric wedge stem performed well with comparable radiological and PROM outcomes at 2 year follow up. Continued follow-up is required for long term benchmarking

Background. Recently the taper wedged stems (TWS) are used widely in Japan because of good bone fixation and ease of the procedure. However, it is unclear how TWS get initial fixation in Japanese, especially dysplasia hip or elderly patients who had stovepipe canal. The purpose of this study is to evaluate initial bone fixation of the TWS in Japanese using computed tomography and to estimate biological bone fixation of the TWS using the Tomosynthesis. Methods. We evaluated 100 hips underwent primary total hip arthroplasty using TWS. All patients were performed computed tomography within 2 weeks postoperatively and evaluated which part of the canal was made contact with the stem. 24 hips were male and 76 hips were female. According to the canal flare index, 9 hips were champagne flute canal, 80 hips were normal canal and 11 hips were Stovepipe canal. 10 hips were Dorr type A, 80 hips were Dorr type B and 10 hips were Dorr type C. The initial bone fixation was classified as Medio-lateral fit (fixed at Gruen zone 2 and 7), Flare fit (fixed at zone 2 and 6), Varus 2-point fit (fixed at zone 3 and 7), Valgus 3-point fit (fixed at zone 2, 5 and 7), Distal fit (fixed at zone 3 and 5), Total fit (fixed at zone 2,3,5,6 and 7) by the stem A-P view. Moreover, we defined Medio-lateral fit, Flare fit and Total fit as Adequate fit, Varus 2-point fit and Valgus 3-point fit as Varus or Valgus fit, Distal fit as Distal fit. The stem alignment was classified as flexion, neutral and extension by the stem lateral view. Femoral component fixation was graded as bone ingrowth, fibrous ingrowth and unstable by hip radiographs after surgery at 1 year. Spot-welds were evaluated using tomosynthesis after surgery at 6 months. Results. 47 hips were Medio-lateral fit, 7 hips were Flare fit, 9 hips were Varus 2-point fit, 12 hips were Valgus 3-point fit, 17 hips were Distal fit and 8 hips were Total fit by the stem A-P view. 63 hips were Flexion, 36 hips were Neutral and 1 hip was Extension by the stem lateral view. 62 hips were Adequate fit, 21 hips were Varus or Valgus fit and 17 hips were Distal fit. Distal fit was identified all canal shape or bone quality regardless of the Canal flare index, the Dorr classification. There was no case of adequate fit which was used larger stem. All cases achieved bone ingrowth fixation, but there were 5 hips which we could not recognize spot-welds. 4 hips of them were classified as Distal fit. Discussion. The study showed that initial bone fixation of the TWS exits various pattern due to femoral geometry, bone quality and stem size. Also most stems were inserted flexion by the stem lateral view. For all hips, tomosynthesis showed stable osseous fixation of the stem regardless of the type of initial bone fixation. Although it is unclear to affect long-term survivorship by the various type of initial bone fixation

Introduction. Alumina-on-alumina in total hip replacement has been used for avoiding osteolysis and loosening. Published series report no ceramic wear and low rates for fractures and noises, but report poor results because of acetabular fixation failure. From 1999 to 2005, we used the “first generation” of a cementless cup, tri-radius relatively-smoothed HA coated (group 1), and from 2006 we have used a “second-generation” of this same cementless cup design with a macrotextured surface (group 2). We compare the perioperative conditions of two groups of patients using these two different cups and the clinical and radiological results. Material and Methods. We analysed 679 (612 patients) consecutive and non-selected primary cementless alumina-on-alumina prostheses. There were 342 hips in group 1 and 337 in group 2. The stem used for all patients in this series was the same and fitted with an Al2O3 liner and femoral head. The use of screws were according to the intraoperative stability of the cup (pull-out test). Patients’ mean age was 48.7+13.6 years and the average follow-up until revision or the last evaluation was 11.7 years for group 1 and 5.4 years for group 2. Results. Group 1, osteopenic and dysplastic acetabulae and women had a higher risk of screw use (p=0.004, p<0.001, p<0.001, p=0.011, respectively). Although the pre-operative clinical score was worse in group 2, the post-operative results were better (p<0.001).). No squeaking was found in any case. No alumina fractures occurred in this series. There was malseating of the liner in three hips, spontaneously resolved at six monthpostsurgery in all cases. No stem loosening, osteolysis or stress shielding were found in any case by the end of follow-up. Changes in linear femoral head penetration were not seen in any hip. There were 17 revised cups due to aseptic loosening, 15 were group 1 and two group 2. The probability of not having cup loosening was 93.3% (95% CI: 89.7 to 96.9) in group 1 and 97.5% (95% CI: 93.5 to 100) in group 2. Cup loosening was more frequent for severe congenital dysplasia of the hip (p<0.001) and in acetabular Dorr’ type C than in other types (p=0.0004). Of the hips revised for aseptic loosening, 6 were inside Lewinnek's safe zone versus 11 cups which was outside this zone (p<0.0001). Multivariate analysis showed that acetabular type C and cups outside Lewinnek´s safe zone had a higher risk for aseptic loosening (p<0.001, HR: 8.088, 95% CI 3.121–20.961; and p=0.003, HR: 5.128, 95% CI 1.773–14.829, respectively). Conclusions. Although the follow-up of this series is too short in the new Cerafit cup to allow definite conclusions, our data suggest that Cerafit alumina-on-alumina prostheses show excellent results after fifteen years. The macrotextured surface of the cup improved fixation compared to the early group Cup loosening was more frequent in severe congenital dysplasia, acetabular Dorr type C and in cups implanted outside of the Lewinnek's safe zone. Continued follow-up is required to determine if reduction in wear between the alumina-on alumina bearings results in less osteolysis, loosening, and late dislocations

Introduction. Cementless grit-blasted tapered-wedge titanium femoral stems are being used with increasing frequency in hip arthroplasty because of excellent long-term outcomes. However, periprosthetic femur fracture is a potentially worrisome phenomenon in these types of femoral stems. The aim of this study is to report the incidence of stem loosening in association with periprosthetic femur fractures following hip arthroplasty using cementless grit-blasted tapered-wedge stems. Materials & Methods. A total of 36 Vancouver Type B1 and B2 periprosthetic femur fractures following either hemiarthroplasty or total hip arthroplasty using cementless grit-blasted tapered-wedge titanium femoral stems (GB group) were identified from a retrospective review of the medical records at three participating academic institutions. The control group consisted of 21 Vancouver Type B1 and B2 periprosthetic femur fractures following either hemiarthroplasty or total hip arthroplasty using cementless proximal porous-coated femoral stems (PC group) at the same institutions during the same period of the study. All femoral stems included in this study had been a well-fixed state before the occurrence of periprosthetic femur fractures. All patients in both groups were treated surgically with either open reduction and internal fixation or femoral stem revision. Femoral stem stability was assessed by preoperative radiographs and was confirmed by intraoperative scrutinization. The incidence of stem loosening was compared between the groups. Results. There was no significant difference between the groups with respect to demographic data including age, gender, body mass index, primary diagnosis, Dorr types of proximal femur, and time to fracture. All fractures occurred from low-energy mechanisms. Mean age at the time of hip arthroplasty was 54.5 years in the GB group and 57.0 years in the PC group. Mean time interval between hip arthroplasty and periprosthetic fracture was 49.6 months in the GB group and 44.4 months in the PC group. At the time of the last follow-up, 29 (80.6%) of 36 fractures was Vancouver B2 in the GB group, whereas only 3 (14.3%) of 21 fractures was Vancouver B2 in the PC group (P <0.001). Conclusions. High incidence of stem loosening was developed in association with periprosthetic femur fractures in previously well-fixed cementless grit-blasted tapered-wedge femoral stems in our population. We believe that this is an underreported phenomenon of these types of stem design

Background. A stem sitting proud (SP) or that above the final rasp position remains in some patients who undergo hip replacement using proximally coated tapered wedge stems. Surgeons may face challenges providing the best fit due to unpredictable stem seating. Zimmer Inc. introduced a new rasp to solve this issue but the clinical results of this rasp have not yet been published. Therefore, we aimed to address the following: 1) What is SP incidence using a proximally coated cementless tapered wedge stem? 2) Does the new rasp system improve seating height? 3) What are the risk factors of SP?. Methods. We performed a retrospective study with 338 hips, in which Tri-Lock Bone Preservation Stem (BPS) was used in 181 and M/L Taper stem was used in 157 hips (82 hips before and 75 hips after the new rasp). A positive stem SP was defined as a stem proud height of >2 mm. We analyzed and compared SP incidence in two stems and in M/L Taper stems before and after the new rasp use. Results. Statistical differences were found across mean age, sex, preoperative diagnosis, and Dorr type between the Tri-Lock BPS and M/L Taper stem groups (P < 0.05); however, no significant difference was found within the M/L Taper groups before and after the 0-mm Rasp use. The sitting proud incidence of the stem was 13% (23/181 hips) with a mean height of 3.0 mm (range: 2.1–4.3 mm) in Tri-Lock BPS and was 15% (12/82 hips) in M/L Taper stem before the 0-mm Rasp use with a mean height of 2.8 mm (range: 2.1–4.0 mm). After the 0-mm Rasp use, only 4% (3/75 hips) showed stem sitting proud with a mean height of 2.2 mm (range: 2.1–2.5 mm). There was no significant difference in the sitting proud incidence between the Tri-Lock BPS and M/L Taper stem groups; however, the sitting proud incidence with M/L Taper stem substantially decreased after the 0-mm Rasp use (P = 0.024). According to the results of the univariate analysis, stem sitting proud was significantly higher at high offset (19%) than at standard offset (8%) in the Tri-Lock BPS system (P < 0.043). In the M/L Taper stem, however, there were no significant differences across all variables, including stem offset, between the stem sitting proud and non-proud groups (Tables 3 and 4). Regarding preoperative diagnosis, the sitting proud incidence was lower in fragility fractures in patients aged ≥50 years (0/18 hips) than in other diagnoses (12/64 hips) using M/L Taper stem before the 0-mm Rasp use, but this result was not statistically significant. When multiple logistic regression analysis was performed, the significant risk factor for stem sitting proud was use of the high offset option in Tri-Lock BPS (P = 0.048; OR = 2.474; 95% CI, 1.009–6.063). There was no substantial difference in the sitting proud incidence between the case groups, each consisting of 30 cases. Regarding femoral head offset, short offset was more frequently used in the stem proud group (13% in Tri-Lock BPS and 58% in M/L Taper stem) than in the non-proud group (4% in Tri-Lock BPS and 21% in M/L Taper stem), and there was a significant difference in M/L Taper stem (P = 0.013). The mean postoperative LLD was 3.0 ± 2.9 mm in Tri-Lock BPS, 3.6 ± 3.2 mm in M/L Taper stem before the 0-mm Rasp use, and 2.7 ± 2.3 mm in M/L Taper stem after the 0-mm Rasp use. There was no significant difference in the mean postoperative LLD between the stem proud and non-proud groups regardless of stem type. At a minimum 6-month follow-up, there was no measurable stem subsidence across all cases. Conclusions. The proximally coated cementless tapered wedge stems are associated with potential problems related to stem sitting proud. The newly developed 0-mm Rasp of M/L Taper stem showed significant improvement in initial seating height compared with the conventional rasp system without postoperative stem subsidence. The use of high offset Tri-Lock BPS stem was the only risk factor for stem proud, but its clinical significance remains unknown. Therefore, large-scale multicenter studies should be conducted to determine relevant risk factors for sitting proud of these stems using a conventional rasp system. For any figures or tables, please contact the authors directly

Dorr bone type is both a qualitative and quantitative classification. Qualitatively on x-rays the cortical thickness determines the ABC type. The cortical thickness is best judged on a lateral x-ray and the focus is on the posterior cortex. In Type A bone it is a thick convex structure (posterior fin of bone) that can force the tip of the tapered implant anteriorly – which then displaces the femoral head posteriorly into relative retroversion. Fractures in DAA hips have had increased fractures in Type A bone because of the metaphyseal-diaphyseal mismatch (metaphysis is bigger than diaphysis in relation to stem size). Quantitatively, Type B bone has osteoclastic erosion of the posterior fin which proceeds from proximal to distal and is characterised by flattening of the fin, and erosive cysts in it from osteoclasts. A tapered stem works well in this bone type, and the bone cells respond positively. Type C bone has loss of the entire posterior fin (stove pipe bone), and the osteoblast function at a low level with dominance of osteoclasts. Type C is also progressive and is worse when both the lateral and AP views show a stove pipe shape. If just the lateral x-ray has thin cortices, and the AP has a tapered thickness of the cortex a non-cemented stem will work, but there is a higher risk for fracture because of weak bone. At surgery Type C bone has “mushy” cancellous bone compared to the hard structure of type A. Tapered stems have high risk for loosening because the diaphysis is bigger than the metaphysis (opposite of Type A). Fully coated rod type stems fix well, but have a high incidence of stress shielding. Cemented fixation is done by surgeons for Type C bone to avoid fracture, and insure a comfortable hip. The large size stem often required to fit Type C bone causes an adverse-stem-bone ratio which can cause chronic thigh pain. I cement patients over age 70 with Type C bone which is most common in women over that age

Background. The direct anterior approach (DAA) for total hip arthroplasty (THA) is marketed with claims of superiority over other approaches. Femoral exposure can be technically challenging and potentially lead to early failure. We examined whether surgical approach is associated with early THA failure. Methods. A retrospective review of 478 consecutive early revision THAs within five years of primary THA at three academic centers from 2011 through 2014 was performed. Exclusion criteria resulted in a final analysis sample of 341 early failure THAs. Primary surgical approach was documented for each revision, along with time to revision, and failure etiology. Results. Early femoral component failure was more common with the DAA (49.6%) than the direct lateral (36.6%) and posterior (13.8%) approaches (p = 0.001). In multivariate regression controlling for age, sex, laterality, Dorr bone type, BMI at revision, bilateral procedure (yes/no), and femoral stem type, the DAA remained a significant predictor of early femoral failure (p = 0.001). The majority of early revisions for instability were associated with the posterior approach (47.5%) and the DAA (37.5%) compared to the direct lateral approach (15.9%, p = 0.0002). Conclusions. Despite claims of early recovery and improved outcomes with the DAA, our findings indicate the DAA likely confers greater risk for early femoral failure and, along with the posterior approach, a greater risk of early instability compared to the direct lateral approach following THA