Purpose. Cementless cup with structural allograft is one of option for acetabular revision in the cases which has severe bone loss. This study was performed to verify that the structural allograft with cementless cup could be one of good options for revision of acetabular cup with severe bone defect and to verify that the allograft resorption affect the stability of cementless acetabular cup. Materials and Methods. We reviewed 25 cases of 25 patients who underwent acetabular cup rvision using cementless porous coated hemispherical cup with structural allograft from May 1992 to July 2011 July 2011. There were nine males and sixteen females with an average age of 50.0 years. The average follow-up period was 76.7(28∼212) months. The clinical evaluation was performed using Harris Hip Score(HHS) and UCLA activity score. Radiologically, the degree of resorption of grafted bone, incorporation of allograft bone with normal bone, osteolysis and cup loosening were evaluated. Results. Clinically, the average Harris hip score was improved from 54 preoperatively to 93.4 at the last follow-up. The average UCLA activity score was also improved from 4.3 preoperatively to 6.4 at the last follow-up. Radiologically, the incorporation of allograft was accomplished in 11.4 months and the resorption of grafted bone was noted in 3 cases(12%), but the allograft resorption had not progressed to moderate degree even in long term follow-up. There was no cup loosening and average survivor rate was 100% in 6 years. There was no infection, allograft nonunion, osteolysis. Conclusion. Cementless cup with structural allograft in acetabular cup reconstruction can provide excellent mi-term results in both clinical and radiological aspects. Structural allograft can provide strong mechanical support for the bone ingrowth of cementless cup. The clinical result of this study auggest that cementless cup with structural allograft can be a good option for acetabular cup revision with severe bone defect. Resorption of structural allograft rarely occurred, and the resorption of structural allograft does not affect stablility of cup even in long term follow-up

Introduction. In most cases of revision acetabular total hip arthoplasty (THA), some degree of bone loss will be accompanied. If the bone loss is massive, the management of bone defect is more challenging problem. We consider that using cementless accetabular cup for revision acetabular reconstruction is good indication when stable interface fit between the acetabular cup and bone is achieved. The purpose of this study is to review the result of revision hip arthroplasty using cementless acetabular cup with and without bone graft. Materials and methods. Between 1998 and 2012, 65 revisions using cementless acetabular cup (Mallory-Head 4 Finned component) were performed in 64 patients, whose mean age was 64.9 years. The cases of revision are aseptic loosening (53 joints), and infection (12 joints). All patients were followed up for a minimum period of 24.0 months (mean, 84 months) and were divided into two groups as follows: in group A, revisions without bone graft (28 joints); in group B, revisions with bone graft (37 joints). We compared clinical and radiographical results of group A with group B. Results. According to Paproski's classification, bone defects in Group A were evaluated as either Type I or Type IIa, and those in Group B were in the range of Type IIb to Type IIIb. Large cementless accetablar compornent with diameters of 58 mm or more were used in 6 joints and 21 cases, respectively. Postoperative radiography showed there were no significant deference of the position of hip center, lateral inclination and anteversion of acetabular cup in each group. The migration of the socket in the superior and medialaxes has not been observed in all cases at the latest follow-up. The mean JOA hip score improved from 63.1 points to 88.3 points and from 53.2 to 86.1, respectively and there were no cases of re-revisions in this series. Conclusions. Depending on the bone defect, large cementless accetablar compornent and bone graft should be considered. We are confident that results of acetabular reconstraction using cementless acetabular cup are satisfactory

Introduction. Bulk bone grafting is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it is a technically demanding surgery with several critical issues, including graft resorption, graft collapse, and cup loosening. The purpose of this study is to describe our new bone grafting technique and review the radiographic and clinical results. Patients and Methods. We retrospectively reviewed 105 hips in 89 patients who had undergone covered bone grafting (CBG) in total hip arthroplasty for developmental dysplasia. We excluded patients who had any previous surgeries or underwent THA with a femoral shortening osteotomy. According to the Crowe classification, 6 hips were classified as group I, 39 as group II, 40 as group III, and 20 as group IV. Follow-up was at a mean of 4.1 (1 ∼ 6.9) years. The surgery was performed using the direct anterior approach. The acetabulum was reamed as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After pressfit fixation of the cup was achieved, several screws were used to reinforce the fixation. Indicating factor for using CBG was a large defect where the acetabular roof angle was more than 45 degrees and the uncovered cup was more than 2 cm (Fig.1). The superior defect of the acetabulum was packed with a sufficient amount of morselized bone using bone dust from the acetabular reamers. Then, the grafted morselized bone was covered with a bone plate from the femoral head. The bone plate was fixed with one screw to compact the morselized bone graft. The patient was allowed to walk bearing full weight immediately after surgery. We measured the height of the hip center from the teardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15 % of the pelvic height, which was nearly equal to 30 mm, because the mean pelvic height was 210 mm. Results. The mean height of the hip center was 9.8 (4.1∼18.0) % of the pelvic height and the 101 (96.2%) cups were placed within the anatomical hip center. Radiographically, in all patients, the host-graft interface became distinct and the new cortical bone in the lateral part of the plate bone appeared within 1 year after surgery (Fig.2, 3). We observed no absorption of the plate bone graft and no migration of the cup at the last follow-up. Conclusion. CBG technique is simple, because the bone graft is always performed after the pressfit of the cup is achieved. Moreover, patients require no partial weight bearing postoperatively, because the cup is supported by the host bone with the pressfit and additional screws. The CBG technique would be an excellent option for the reconstruction of the acetabulum in patients with severe dysplasia to avoid a high hip center and bulky bone grafting

Introduction. Bulk bone grafting of the cup is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it carries a risk of the graft collapse in the mid-term or long-term results. The purpose of this study is to describe our new bulk bone grafting technique and review the radiographic and clinical results. Patients and Methods. We retrospectively reviewed 85 hips in 74 patients who had undergone bulk bone grafting in total hip arthroplasty for developmental dysplasia between 2008 and 2013. We excluded patients who had any previous surgeries or performed THA with the femoral shortening osteotomy. According to the Crowe classification, 4 hips were classified as Type 1, 28 as Type 2, 35 as Type 3, and 18 as Type 4. Follow-up was at a mean of 4.0 years (1 to 6.1). The surgery was performed using the direct anterior approach on a standard surgical table. The acetabulum was reamed for as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After the pressfit fixation of the cup was achieved, two or three screws were used to reinforce the fixation. The superior defect of the acetabulum was packed with sufficient amount of morselized bone graft. Then, the bulk bone was placed on the morselized bone graft and fixed with one screw. Post-operatively, there were no restrictions to movement or position. On the first day after surgery, the patient was allowed to walk with full weight-bearing. We measured the height of the hip center from the interteardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15% of the pelvic height. Results. The mean height of the hip center was 10.2 (4.1∼18.0)% of the pelvic height and the 81 (95.2%) cups were placed within the anatomical hip center. We observed no collapsed grafts, no severe absorption of the grafts, and no migration of the cup at the last follow-up. Conclusion. In our technique, there is no concern of the bulk bone graft collapse even in the long-term results, because the cup is not supported by the bulk bone graft but by the host bone with the pressfit and additional screws. Moreover, 95.2% of all cups were placed within the anatomical hip center. In conclusion, our new bulk bone graft technique would be simple to perform and an excellent option for the reconstruction of the acetabulum in patients with severe dysplasia

Introduction

The mid- or long-term results of acetabular revision total hip arthroplasty (THA) in Korea are rare. The purpose of this study is to report the mid-term radiographic results (> 5 years) of acetabular revision THA with porous-coated cementless Trilogy^® cup (Zimmer, Warsaw, IN, USA).

Objectives. Total hip replacement is increasingly being conducted in younger and more active patients, so surgeons often use bearing surfaces with improved wear characteristics, such as ceramic on ceramic. The primary objective of this study was to determine if survivorship for a BIOLOX® delta ceramic on delta ceramic couple used with the PROCOTYL® L acetabular cup is significantly different from all other cementless cups in a large arthroplasty registry. The secondary objective of this study was to analyze patient reported outcomes measures (PROMs) of the subject cup with a minimum five year follow-up. Methods. Patient demographics and survivorship data was collected from the National Joint Registry of England, Wales, Northern Ireland, and the Isle of Man (NJR) database for all total hip replacements performed with the PROCOTYL® L cup used in combination with a delta-on-delta articulation, as well as for all other cementless cups. Survivorship data was compared for all revisions and cup revisions only and data was adjusted to exclude metal on metal articulations. The hazard ratio of the subject system to all cementless cups was also calculated with the Cox Proportional Hazards model. Patients with the subject components implanted for a minimum of five years completed Oxford Hip, EQ-5D, and EQ VAS score questionnaires. Results. The patient demographic data collected for the subject components and all cementless cups is provided in Figure 1. Six-year survivorship for the subject cup (98.6%) was similar to survivorship for all cementless cup revisions in the NJR database (98.5%), as seen in Figure 2. When the cup alone was revised, six-year survivorship of the subject cup (98.6%) and all NJR cementless cups (98.5%) was also similar. However, the subject cup survivorship remained at 98.6% from 4 to 6 years post-implantation, while survivorship for all cementless cups decreased slightly from years 4 to 6. The similarities between the revision risk of the subject system and all cementless cups in the NJR can be seen in the Cox Proportional Hazards model for revision risk ratios provided in Figure 3. Patients with the subject cup implanted for an average of 5.88 years reported Oxford Hip, EQ-5D, and EQ VAS scores of 39.60 ± 10.78, 0.801 ± 0.259, and 75.49 ± 19.25, respectively. Conclusions. The subject acetabular cup with a ceramic on ceramic articulation exhibited similar survivorship to all other cementless acetabular cups, excluding those with metal on metal bearings, in the NJR. Patients implanted with the subject system for an average of 5.88 years reported what are considered satisfactory Oxford Hip, EQ-5D, and EQ VAS scores. This survivorship and PROMs data is the first report of mid-term outcomes with the subject components

Introduction. The National Joint Registry of England, Wales, Northern Ireland, and the Isle of Man (NJR) monitors the performance of primary total hip arthroplasty (THA) implants and summarizes usage and outcomes for specific hip systems. The objectives of this study were to 1) determine if survivorship for the PROCOTYL® L acetabular cup, a hemispherical press-fit cup coated with hydroxyapatite and a metal on XLPE articulation, is significantly different from all other cementless cups in the NJR and 2) to analyze patient reported outcomes measures (PROMs) at a minimum five year follow-up for the subject cup. Methods. The database of the NJR was searched for demographic information and survivorship data for all THAs performed with the PROCOTYL® L cup (metal on XLPE) and all other cementless cups. Survivorship data for both groups was adjusted to exclude metal on metal bearings and compared for all revisions and acetabular revisions only. The Cox Proportional Hazards model for the revision risk ratio of the subject cup to all cementless cups was also calculated. Patients with the subject cup implanted for at least five years were mailed a PROMs program questionnaire consisting of the Oxford Hip, EQ-5D, and EQ VAS scores. No pre-operative PROMs scores were collected. Results. Patient demographic information for the subject system and all cementless cups is provided in Figure 1. As seen in Figure 2, the six-year survivorship for the 1,172 THAs using the subject system (97.8%) was slightly higher than the survivorship for all cementless cups (97.5%), but the difference was not statistically significant (Figure 3). The 1, 2, and 5 year survivorship for the subject cup also exceeded the survivorship of all cementless cups, but without statistically significant differences. When just the cup was revised, the subject system survivorship was similar to survivorship for all cementless cups for years 1 through 6 (Figure 2). Patients with the subject system implanted for an average of 5.73 – 5.75 years reported average Oxford Hip, EQ-5D, and EQ VAS Scores of 39.13 ± 9.93, 0.775 ± 0.273, and 75.87 ± 17.71, respectively. Conclusions. The subject acetabular cup was associated with survivorship similar to that of other cementless acetabular cups. Patients implanted with the subject system for at least five years reported what are considered satisfactory Oxford Hip, EQ5D, and EQVAS score outcomes. These results represent the first report of midterm outcomes with the subject system. For figures/tables, please contact authors directly.

Total hip arthroplasty (THA) is one of the preferable solutions for regaining ambulatory activity for patients with end-stage osteoarthritis, and the procedure is well developed technically and large numbers of patients benefit from THA worldwide. However, despite the improvements in implant designs and surgical techniques, revision rates remain high, and the number of revisions is expected to increase in the future as a result of the increase in the volume of primary THA and the increase in the proportion of younger, more active patients who are likely to survive longer than their prosthetic implants. In revision THA, associated loss of bone stock in the acetabulum presents one of the major challenges. The aim of the present study was to analyze the clinical and radiographic outcomes and Kaplan-Meier survivorship of patients underwent revision surgeries of the acetabular cup sustaining aseptic loosening. We reviewed consecutive 101 patients (120 hips; 10 men 11 hips; 91 women 109 hips; age at surgery, 66 years, range, 45–85) who underwent acetabular component revision surgery, at a follow-up period of 14.6 years (range, 10–30). For the evaluation of the state of the acebtabulum, acetabular bony defects were classified according to the classification of the AAOS based on the intraoperative findings as follows; type I [segmental deficiencies] in 24 hips, type II [cavity deficiency] in 48 hips, type III [combined deficiency] in 46, and type IV [pelvic discontinuity] in 2. Basically, we used the implant for acetabular revision surgery that cement or cementless cups were for the AAOS type I acetabular defects, cementless cup, or cemented cup with reinforcement device were for type II, cemented cup with reinforcement device were for type III. Follow-up examination revealed that Harris Hip score improved from 42.5±7.8 points before surgery to 76±16.2 points (p<0.05). The survival rates of the acetabular revision surgery with cemented cups, cementless cups, and cemented cups with reinforcement devices were 65.1%, 72.8%, and 79.8%, respectively, however, there was no significant differences between the groups. There were nine cases, which failed in the early stage in the groups of cementless cups and cemented cups with reinforcement devices, because of the instability of the cementless cups or breakage of reinforcement plates caused by inadequate bone grafting. We conclude that the usage of the cementless cups for type I and II acetabular bony defects, and the cemented cups with reinforcement devices for type III bony defects will demonstrate durable long-term fixation in case of adequate contact between acetabular components and host-bone with restoration of bone stock by impaction bone grafting

Introduction. Few studies are published about total hip arthroplasties (THA) in Parkinson's disease as it is often considered as a contraindication for hip replacement. THA for fracture is reported as a high complication rate surgery. Regarding bone quality these cases are assimilated to elderly patients and cemented implants are generally preferred. However, due to the improved length and quality of life, we face more potential indications for joint replacement. The aim of this study is to report our experience of cementless dual mobility implants for primary THAs for osteoarthrosis and THA revisions focusing on the risks and benefits of surgery. Material and methods. 65 THA were performed in 59 patients (34 men, 25 women, mean age 73 years, 55–79). Mean latest follow-up was 8,3 years (4–14). Indications were 42 primary THA (osteoarthrosis) and 21 revisions (11 recurrent dislocation, 6 acetabular PE wear, 4 femoral loosening). Surgical approach was always antero-lateral. All patients were implanted with the same dual mobility cementless cup. The same cementless corail-type stem was used for primary THA cases. All the cemenless implants were hydroxyapatite coated. The disability caused by the disease was classified according to Hoehn and Yahr. (19 stage 1, 21 stage 2,16 stage 3). Results. 2 patients were lost for follow-up before 2 years. general complications were 3 pulmonary infection, 7 urinary tract infection, 12 cognitive impairment and 2 sacral pressure ulcer. A post-op. wound infection (E Coli) required an early revision in 2 cases without secondary consequencies (7 and 9 years follow-up). We did not observe early or late THA dislocation except in one case at 9 years follow-up (intraprosthetic dislocation due to an increase of ilio psoas muscle retraction requiring a revision of the dual mobility mechanism). We did not observe loosening cases of the cementless cup. 4 patients fell and fractured the femur. The cementless cup was not affected. 10 patients died. Good to excellent pain relief was achieved in 53/57cases at 2 years and in 40/47 cases at latest follow-up. The progression of neurological disability was observed in most of cases. At the latest follow-up for the 47 remaining patients, we had 5 stage 1, 12 stage 2, 21 stage 3,9 stage 4. Discussion. According to literature infection and dislocation are the main concerns for THA in Parkinson patients. This study does not report any trauma cases; this may explain the rather good results on a mean follow-up to more than 8 years. Nevertheless progression of Parkinson's disease is the rule, with significant disability or even death (10 /57 cases). Cementless fixation is possible even on the acetabular side. The poor bone quality of these patients was not an argument against hydroxyapatite coated implants. Conclusion. THA in Parkinson's disease is a challenging surgery due to associated comorbidity. For all patients the functional status improved in the early follow-up and declined with the disease progression. Cementless dual mobility cups and femoral stems can be used with a very low rate of mechanical complication

Protrusio acetabuli (arthrokatadysis or Otto pelvis) is a relatively rare condition associated with secondary osteoarthritis of the hip. Radiographically, protrusio acetabuli is present when the medial aspect of the femoral head projects medial to Kohler's (ilioischial) line. This results in medialization of the center of rotation (COR) of the hip. Protrusio acetabuli is typically associated with metabolic bone disease (osteoporosis, osteomalacia, Paget's disease) or inflammatory arthritis (RA or ankylosing spondylitis). Idiopathic acetabular protrusio can occur without the above associated factors however. Patients with protrusio acetabuli typically present with significant restriction of range of motion (ROM) of the hip due to femoral neck and trochanteric impingement in the deep acetabular socket and pain associated with secondary osteoarthritis (OA). Total hip arthroplasty (THA) in patients with protrusion acetabuli is more challenging than THA in patients with a normal hip COR. ROM is typically quite restricted which can compromise surgical exposure. Dislocation of the hip in the patient with a deep socket and medialised COR can be extremely difficult and associated with fracture of the femur if not carefully performed. Restoration of the hip COR to the normal more lateralised position is a principle goal of surgery. This restores more normal mechanics of the hip and has been associated with improved durability. A variety of techniques to accomplish this have been described including medial acetabular bone grafting with cemented cups, protrusio rings or porous coated cementless cups fixed with multiple screws. The latter technique has been shown to be more durable and associated with better outcomes. THA in protrusio acetabuli starts with templating of the preoperative x-rays to determine the optimal acetabular implant size and final position of the acetabular component that restores the hip COR to the normal position. Patients with protrusio acetabuli often have varus oriented femoral necks and the femur needs to be carefully templated as well to insure that an appropriate femoral component is available that will allow for restoration of the patient's anatomy. Cartilage covering the thinned medial wall needs to be carefully removed without disruption of the medial acetabular wall. The acetabulum is then carefully reamed with the goal of obtaining stable peripheral rim support of a cementless socket and at least 50% contact of the implant on good quality host bone. Unlike acetabular preparation in the normal hip, preventing the reamer from “bottoming out” is essential in order to obtain desired rim support and return of the hip COR to the normal lateralised position. When good rim support of the reamer is obtained, a trial component is placed and intraoperative x-ray obtained to confirm fit, position and restoration of hip COR. Limited addition reaming can be performed to obtain desired degree of press fit (1‐2mm) and contact with host bone. Morselised autograft from the femoral head and neck is then packed into the medial defect and reverse reamed. The cementless acetabular component is then impacted into position and fixed with screws. Weight bearing is determined by bone quality, size and containment of the medial defect, amount of contact of the cementless cup with host bone and stability of the acetabular construct. Incorporation of autograft bone in the acetabulum and stable long term fixation occurs reliably if stable initial press-fit fixation of the cementless cup is obtained. Restoration of hip COR to within 7mm of its normal location is associated with better implant survival

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

The objective of this study was to evaluate the short term clinical and radiological results of a new short stem hip implant. In 29 consecutive patients suffering from osteoarthritis with 33 affected hip joints, the clinical and radiological results of 33 cementless hip arthroplasties using a cementless implanted short stem prosthesis type Aida and a cementless cup type Ecofit were evaluated prospectively between October 2009 and June 2015 in two hospitals. The median age of patients at time of surgery was 55 years (range, 30–71 years), 23 male and 10 female patients were included in the study. The median clinical follow up was 24 months (range, 1.5–51 months), and the median radiological follow up was 12 months (range, 1–51 months). Two patients were lost to follow up and two patients had only one immediate postoperative x- ray. The Harris Hip Score improved from a median preoperative value of 53 to a median postoperative value of 93 at follow up. Radiological analysis showed that 19 stems (58%) showed stable bony ingrowth, five cases (15%) showed stable fibrous ingrowth. Four cases need further follow up for proper evaluation of stem fixation. The short term survival of this new short stem is very promising, and achieving the goals of standard hip arthroplasty

Aims. Severe, superior acetabular bone defects are one of the most challenging aspects to revision total hip arthroplasty (THA). We propose a new concept of “superior extended fixation” as fixation extending superiorly 2 cm beyond the original acetabulum rim with porous metal augments, which is further classified into intracavitary and extracavitary fixation. We hypothesized that this new concept would improve the radiographic and clinical outcomes in patients with massive superior acetabular bone defects. Patients and Methods. Twenty eight revision THA patients were retrospectively reviewed who underwent reconstruction with the concept of superior extended fixation from 2014 to 2016 in our hospital. Patients were assessed using the Harris Hip Score (HHS) and the Western Ontario and McMaster Universities Osteoarthritis Index score (WOMAC). In addition, radiographs were assessed and patient reported satisfaction was collected. Results. At an average follow-up of 28 months (range 18 – 52 months), the postoperative HHS and WOMAC scores were significantly improved at the last follow-up (p < 0.001). The postoperative horizontal and vertical locations of the COR from the interteardrop line were significantly improved from the preoperative measurements (p < 0.001). One (3.6 %) patient was dissatisfied due to periprosthetic joint infection. Conclusion. Extracavitray and intracavitary superior extended fixation with porous metal augments and cementless cups are effective in reconstructing severe superior acetabular bone defects, with promising short-term clinical and radiographic outcome

INTRODUCTION. Reaming of the acetabular cavity prior to cementless cup implantation aims to create a defined press-fit between implant and bone. The goal is to achieve full implant seating with the desired press-fit to reduce the risk of early cup loosening and the risk of excessive cup deformation. Current research concentrated on the spherical deviations of the reamed cavity compared to the reamer size, but the direct relationship between nominal press-fit, reamer geometry, cavity shape and bone-implant contact has not yet been investigated. The aim of this study was to determine the influence of the reaming process, the surface coating, and the implantation force on the achieved press-fit situation. METHODS. Fresh-frozen porcine acetabulae (n = 20) were prepared and embedded. Hemispherical reamers were used and the last reaming step was performed using a vertical drilling machine to ensure a proper alignment of the cavity axis. A hand-guided 3D laser scanner was used (HandySCAN 700, Creaform) to determine the reamer geometry and the cavity shape. Press-fit cups with two different surface coatings (Ø44 mm, Porocoat/Gription, DePuy Synthes) were implanted using a drop tower. The Porocoat cup was implanted with impacts from lower drop heights (low implantation force) and press-fits of 1 mm and 2 mm. The Gription cup, exhibiting a rougher surface, was implanted with low and high implantation forces and a press-fit of 1 mm. Bone-implant contact was analysed by the registration of the cup and cavity surface models, scanned prior to implantation, to the scan of the implanted cup. The cup surface was divided in areas with and without contact to the surrounding cavity. Overhang indicates that there was no adjacent cavity surface surrounding the implanted cup. The transition between contact and a gap at the cup dome was defined as contact depth and used as indicator for the cup seating. RESULTS. The peripheral cavity diameter was on average 0.94 ± 0.29 mm smaller than the reamer diameter due to the sub-hemispherical distribution of the cutting blades. This led to an increased effective press-fit in the peripheral area of the cavity. The contact area between cup and bone increased with the implantation force (p = 0.008) and ranged from 13.1 % to 27.8 %. The contact depth was larger for the smoother Porocoat coating (p = 0.008), a press-fit of 2 mm (p = 0.008) and a higher implantation force (p = 0.008). DISCUSSION. This study shows that, assuming similar implantation forces, an increased surface roughness of the cup coating increases the risk of an insufficient cup seating. For a given press-fit, higher implantation forces would be necessary to fully seat the cup in order to enhance the bone-implant contact. Implantation of a cup without a defined nominal press-fit could increase the contact area; however a high reaming accuracy and an increased friction coefficient of the cup coating are required to compensate for a reduction in initial fixation strength caused by reduced radial compressive forces. For any figures or tables, please contact authors directly

Introduction. Robotic-assisted hip arthroplasty helps acetabular preparation and implantation with the assistance of a robotic arm. A computed tomography (CT)-based navigation system is also helpful for acetabular preparation and implantation, however, there is no report to compare these methods. The purpose of this study is to compare the acetabular cup position between the assistance of the robotic arm and the CT-based navigation system in total hip arthroplasty for patients with osteoarthritis secondary to developmental dysplasia of the hip. Methods. We studied 31 hips of 28 patients who underwent the robotic-assisted hip arthroplasty (MAKO group) between August 2018 and March 2019 and 119 hips of 112 patients who received THA under CT-based navigation (CT-navi group) between September 2015 and November 2018. The preoperative diagnosis of all patients was osteoarthritis secondary to developmental dysplasia of the hip. They received the same cementless cup (Trident, Stryker). Robotic-assisted hip arthroplasty were performed by four surgeons while THA under CT-based navigation were performed by single senior surgeon. Target angle was 40 degree of radiological cup inclination (RI) and 15 degree of radiological cup anteversion (RA) in all patients. Propensity score matching was used to match the patients by gender, age, weight, height, BMI, and surgical approach in the two groups and 30 patients in each group were included in this study. Postoperative cup position was assessed using postoperative anterior-posterior pelvic radiograph by the Lewinnek's methods. The differences between target and postoperative cup position were investigated. Results. The acetabular cup position of all cases in both Mako and CT-navi group within Lewinnek's safe zone (RI: 40±10 degree; RA: 15±10 degree) in group were within this zone. Three was no significant difference of RI between Mako and CT-navi group (40.0 ± 2.1 degree vs 39.7± 3.6 degree). RA was 15.0 ± 1.2 degree and 17.0 ± 1.9 degree in MAKO group and in CT-navi group, respectively, with significant difference (p<0.001). The differences of RA between target and postoperative angle were smaller in MAKO group than CT-navi group (0.60± 1.05 degree vs 2.34± 1.40 degree, p<0.001). The difference or RI in MAKO group was smaller than in CT-navi, however, there was no significance between them (1.67± 1.27 degree vs 2.39± 2.68 degree, p=0.197). Conclusions. Both the assistance of the robotic arm and the CT-based navigation system were helpful to achieve the acetabular cup implantation, however, MAKO system achieved more accurate acetabular cup implantation than CT-based navigation system in total hip arthroplasty for the patients with OA secondary to DDH. Longer follow-up is necessary to investigate the clinical outcome

INTRODUCTION. Hip resurfacing offers a more bone conserving solution than total hip replacement (THR) but currently has limited clinical indications related to some poor design concepts and metal ion related issues. Other materials are currently being investigated based on their successful clinical history in THR such as Zirconia Toughened Alumina (ZTA, Biolox Delta, CeramTec, Germany) which has shown low wear rates and good biocompatibility but has previously only been used as a bearing surface in THR. A newly developed direct cementless fixation all-ceramic (ZTA) resurfacing cup offers a new solution for resurfacing however ZTA has a Young's modulus approximately 1.6 times greater than CoCr - such may affect the acetabular bone remodelling. This modelling study investigates whether increased stress shielding may occur when compared to a CoCr resurfacing implant with successful known clinical survivorship. METHODS. A finite element model of a hemipelvis constructed from CT scans was used and virtually reamed to a diameter of 58mm. Simulations were conducted and comparisons made of the ‘intact’ acetabulum and ‘as implanted’ with monobloc cups made from CoCr (Adept®, MatOrtho Ltd, UK) and ZTA (ReCerf ™, MatOrtho Ltd. UK) orientated at 35° inclination and 20° anteversion. The cups were loaded with 3.97kN representing a walking load of 280% for an upper bound height patient with a BMI of 35. The cup-bone interface was assigned a coulomb slip-stick function with a coefficient of friction of 0.5. The percentage change in strain energy density between the intact and implanted states was used to indicate hypertrophy (increase in density) or stress shielding (decrease in density). RESULTS. Implanting both cups changed the strain distribution observed in the hemipelvis, Figure 1. The change in strain distribution was similar between materials and indicated a similar response from the bone, Figure 2. In both implanted cases, the inferior peri-acetabular bone around the implant indicated a reduction in bone strain. The bone remodelling distribution charts show that regardless of threshold remodelling stimulus level (75% in elderly, 50% in younger patients) the CoCr and ZTA cups were expected to produce the same bone response with only a small percentage of the bone in the hemipelvis indicating stress shielding or hypertrophy, Figure 3. DISCUSSION. Currently only metal cups are used for cementless fixation but improvements in design and technology have made it possible to engineer a thin-walled, direct fixation, all-ceramic cup. Both CoCr and ZTA are an order of magnitude greater than the Young's modulus of cortical bone altering the bone strain but changing the material from CoCr to a stiffer ZTA did not change the expected bone remodelling response. Given the clinical history of metal cups without loosening due to bone remodelling, the study indicates that a ZTA cup should not lead to increased stress shielding and is potentially suitable for as a cementless cup for both resurfacing and THR. SIGNIFICANCE. An all-ceramic cup is unlikely to lead to increased stress shielding around the acetabulum due to the change in material. For any figures or tables, please contact the authors directly

One cementless cup which had porous outer surface with Apatite-Wollastonite glass ceramic (AWGC) coating, was revised 13 years after primary THA because of massive osteolysis expanded to medial iliac wall along the screws. While many retrieved studies of hydroxyapatite-coated cup have been reported, there has been no report on the retrieved cup with AWGC coating. The purpose of this study was to describe this rare case in detail, confirm the bone ingrowth to the porous cup, and discuss on the effectiveness of porous surface with AWGC coating. Case. The patient was a 64 old woman and complained of chronic mild pain around her left groin region. X-ray examination revealed that osteolysis had been expanding around the screws and extended proximally. The revision surgery was performed for the massive osteolysis through Hardinge antero-lateral approach. The retrieved implants included a cementless cup made of titanium alloy (QPOC cup, Japan Medical Materirals Inc.(JMM) Osaka, Japan), the outer surface of which was plasma-sprayed with titanium for porous formation and coated with AWGC in the deep layer. It was found that the polyethylene liner was destructed partially in the supero-lateral portion, but the cup was well fixed to the bone. The bone-attached area was found to be dispersed over the porous surface of the hemispherical cup. Histological examination revealed that matured bony tissue intruded into the porous surface of the cup, and contacted to bone directly, which was also demonstrated in the back-scattered electron image. It was also demonstrated that there were residual silicon (Si) rich regions on the porous surface by the SEM-EDX analysis, which indicated that constituents of AWGC still remained on the surface. On the other hand, the results of elementary analyses in the Si rich regions varied among the sections, which probably indicated that the extent of degradation and absorption of AWGC varied among the sections. AWGC was one of the bioactive ceramics and reported to have an ability to bond to bone earlier than hydroxyapatite (HA). In the present case, though massive osteolysis occurred with aggressive wear, it did not expand on the porous surface, and rather progressed along the smooth surface of the screws. Considering that there are many clinical studies reporting poor clinical results of HA-coated smooth cups, bioactive ceramic coating may function well and bring superior clinical results when combined with porous coated substrate. In our study, though the cause of massive polyethylene wear and intrapelvic giant osteolysis could not be revealed, the porous cup with AW-GC bottom coating was well fixed and gained bone-ingrowth at the porous surface under osteolytic conditions, which may demonstrate the long-term durability of this surface treatment

Aim. The objective of this study was to evaluate the intermediate term clinical and radiological results of a new short stem hip implant. Methods. In 20 consecutive patients suffering from osteoarthritis with 25 affected hip joints (five cases were bilateral), the clinical and radiological results of 25 hip arthroplasties performed in one hospital between October 2009 and May 2014 through a minimally invasive anterolateral approach using a cementless short stem prosthesis type Aida and a cementless cup type Ecofit with a ceramic on ceramic pairing were evaluated prospectively. The median age of patients at time of surgery was 60 years (range, 42–71 years), 15 male (4 were bilateral) and 5 female patients (one was bilateral) were included in the study. The median clinical follow up was 30 months (range, 2–88 months), and the median radiological follow up was 30 months (range, 2–88 months). Results. Harris Hip Score improved from a median preoperative value of 53 to a median postoperative value of 96 (range, 73–100) at follow up. 22 hips (88%) showed an excellent postoperative Harris Hip Score, 2 hips (8%) a good postoperative Harris Hip Score, and one hip (4%) a fair postoperative Harris Hip Score. Only two patients complained of postoperative thigh pain. Regarding patient satisfaction, 15 patients (60%) were very satisfied, 10 patients (40%) were satisfied. None was unsatisfied. Radiological analysis showed that 19 stems (76%) were with stable bony ingrowth, two cases (8%) showed stable fibrous ingrowth. Four cases need further follow up for proper evaluation of stem fixation.(See Figures 1,2,3). Conclusion. The intermediate term survival of this new short stem is very promising, and achieving the goals of a standard hip arthroplasty. For any figures or tables, please contact the authors directly

The purpose of this preliminary study was to evaluate the feasibility and accuracy of HipAlign (OrthAlign, Inc., USA) system for cup orientation in total hip arthroplasty (THA). The subjects of this study were 5 hips that underwent primary cementless THA via a posterior approach in the lateral decubitus position. Evaluation 1; after reaming acetabular bone, a trial cup was placed in the reamed acetabulum in an aimed alignment using HipAlign. Then, the trial cup alignment was measured using HipAlign and CT-based navigation system in the radiographic definition. Evaluation 2; a cementless cup was placed in the reamed acetabular in an aimed alignment using CT-based navigation and cup alignment was measured using both methods. After operation, we measured the cup alignment using postoperative CT in each patient. In the results, the average cup inclination measured with HipAlign was around 5 degrees of true cup inclination angles. The average cup anteversion with HipAlign tended to be larger than that with CT-based navigation or postoperative CT in both evaluations. That is because there is a difference in the pelvic sagittal tilt between the lateral position and supine position. In conclusion, this study suggests that guiding cup alignment with the use of HipAlign is feasible through a posterior approach and the mean cup inclination measured with HipAlign showed an acceptable level of accuracy, but the mean cup anteversion is not reliable. We need a further modification for pelvic registration to improve the accuracy of cup anteversion

The indications for cementless acetabular fixation have been broadened because our data supports the use of trabecular metal cups even when there's limited bleeding host bone contact. Trabecular metal augments have allowed us to use cementless cups when there is segmental loss of bone. Surgical Technique: The acetabular bed is prepared. If there is less medial bone stock than 2mm, then morselised allograft is impacted by reverse reaming. When reaming is complete and less than 50% bleeding host bone is available for cup stabilisation, then a trabecular metal cup is indicated. Trabecular augments are used if the trabecular cup trial is not stable, or if it is uncovered by 40% or more. The conventional augments come in different sizes to accommodate the diameter of the cup and the size of the defect. Larger defects are addressed with anterior and posterior column augments, and superior defects with figure of seven augments. Augments are fixed with at least two screws. The interface between the cup and the augments should be stable, but some surgeons place a very thin layer of cement between the augment and cup so micromotion does not occur while ingrowth is occurring. We have used trabecular metal augments in 46 acetabular revisions in conjunction with a trabecular metal cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There have been 4 cup loosenings with 3 re-revisions