Custom acetabular components have become an established method of treating massive acetabular bone defects in hip arthroplasty. Complication rates, however, remain high and migration of the cup is still reported. Ischial screw fixation (IF) has been demonstrated to improve mechanical stability for non-custom, revision arthroplasty cup fixation. We hypothesise that ischial fixation through the flange of a custom acetabular component aids in anti-rotational stability and prevention of cup migration. Electronic patient records were used to identify a consecutive series of 49 custom implants in 46 patients from 2016 to 2022 in a unit specializing in complex joint reconstruction. IF was defined as a minimum of one screw inserted into the ischium passing through a hole in a flange on the custom cup. The mean follow-up time was 30 months. IF was used in 36 cups. There was no IF in 13 cups. No difference was found between groups in age (68.9 vs. 66.3, P = 0.48), BMI (32.3 vs. 28.2, P = 0.11) or number of consecutively implanted cups (3.2 vs. 3.6, P = 0.43). Aseptic loosening with massive bone loss was the primary indication for revision. There existed no difference in Paprosky grade between the groups (P = 0.1). 14.2% of hips underwent revision and 22.4% had at least one dislocation event. No ischial fixation was associated with a higher risk of cup migration (6/13 vs. 2/36, X2 = 11.5, P = 0.0007). Cup migration was associated with an increased risk for all cause revision (4/8 vs. 3/38, X2 = 9.96, P = 0.0016, but not with dislocation (3/8 vs. 8/41, X2 = 1.2, P = 0.26). The results suggest that failure to achieve adequate ischial fixation, with screws passing through the flange of the custom component into the ischium, increases the risk of cup migration, which, in turn, is a risk factor for revision

Aims. Custom triflange acetabular components (CTACs) play an important role in reconstructive orthopaedic surgery, particularly in revision total hip arthroplasty (rTHA) and pelvic tumour resection procedures. Accurate CTAC positioning is essential to successful surgical outcomes. While prior studies have explored CTAC positioning in rTHA, research focusing on tumour cases and implant flange positioning precision remains limited. Additionally, the impact of intraoperative navigation on positioning accuracy warrants further investigation. This study assesses CTAC positioning accuracy in tumour resection and rTHA cases, focusing on the differences between preoperative planning and postoperative implant positions. Methods. A multicentre observational cohort study in Australia between February 2017 and March 2021 included consecutive patients undergoing acetabular reconstruction with CTACs in rTHA (Paprosky 3A/3B defects) or tumour resection (including Enneking P2 peri-acetabular area). Of 103 eligible patients (104 hips), 34 patients (35 hips) were analyzed. Results. CTAC positioning was generally accurate, with minor deviations in cup inclination (mean 2.7°; SD 2.84°), anteversion (mean 3.6°; SD 5.04°), and rotation (mean 2.1°; SD 2.47°). Deviation of the hip centre of rotation (COR) showed a mean vector length of 5.9 mm (SD 7.24). Flange positions showed small deviations, with the ischial flange exhibiting the largest deviation (mean vector length of 7.0 mm; SD 8.65). Overall, 83% of the implants were accurately positioned, with 17% exceeding malpositioning thresholds. CTACs used in tumour resections exhibited higher positioning accuracy than rTHA cases, with significant differences in inclination (1.5° for tumour vs 3.4° for rTHA) and rotation (1.3° for tumour vs 2.4° for rTHA). The use of intraoperative navigation appeared to enhance positioning accuracy, but this did not reach statistical significance. Conclusion. This study demonstrates favourable CTAC positioning accuracy, with potential for improved accuracy through intraoperative navigation. Further research is needed to understand the implications of positioning accuracy on implant performance and long-term survival. Cite this article: Bone Jt Open 2024;5(4):260–268

Aims. To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time. Methods. We performed a single-centre historical prospective cohort study, including all patients with revision THA using the aMace CTAC between January 2017 and March 2021. A total of 18 patients (18 CTACs) were included. Models of the hemipelvis and the scaffold component of the CTACs were created by segmentation of CT scans. The CT scans were performed immediately postoperatively and at least one year after surgery. The amount of bone in contact with the scaffold was analyzed at both times, and the difference was calculated. Results. The mean time between the implantation and the second CT scan was two years (1 to 5). The mean age of the patients during CTAC implantation was 75 years (60 to 92). The mean scaffold-bone contact area increased from 16% (SD 12.6) to 28% (SD 11.9). The mean scaffold-bone distance decreased from a mean of 6.5 mm (SD 2.0) to 5.5 mm (SD 1.6). None of the CTACs were revised or radiologically loose. Conclusion. There was a statistically significant increase of scaffold-bone contact area over time, but the total contact area of the scaffold in relation to the acetabular bone remained relatively low. As all implants remained well fixed, the question remains to what extend the scaffold contributes to the observed stability, in relation to the screws. A future design implication might be an elimination of the bulky scaffold component. This design modification would reduce production costs and may optimize the primary fit of the implant. Cite this article: Bone Joint J 2024;106-B(4):359–364

The custom triflange is a patient-specific implant for the treatment of severe bone loss in revision total hip arthroplasty (THA). Through a process of three-dimensional modelling and prototyping, a hydroxyapatite-coated component is created for acetabular reconstruction. There are seven level IV studies describing the clinical results of triflange components. The most common complications include dislocation and infection, although the rates of implant removal are low. Clinical results are promising given the challenging problem. We describe the design, manufacture and implantation process and review the clinical results, contrasting them to other methods of acetabular reconstruction in revision THA. Cite this article: Bone Joint J 2016;98-B(1 Suppl A):68–72

The best treatment method of large acetabular bone defects at revision THR remains controversial. Some of the factors that need consideration are the amount of residual pelvic bone removed during revision; the contact area between the residual pelvic bone and the new implant; and the influence of the new acetabular construct on the centre of rotation of the hip. The purpose of this study was to compare these variables in two of the most used surgical techniques used to reconstruct severe acetabular defects: the trabecular metal acetabular revision system (TMARS) and a custom triflanged acetabular component (CTAC). Pre- and post-operative CT-scans were acquired from 11 patients who underwent revision THR with a TMARS construct for a Paprosky IIIB defect, 10 with pelvic discontinuity, at Royal Adelaide Hospital. The CT scans were used to generate computer models to virtually compare the TMARS and CTAC constructs using a semi-automated method. The TMARS construct model was calculated using postoperative CT scans while the CTAC constructs using the preoperative CT scans. The bone contact, centre of rotation, inclination, anteversion and reamed bone differences were calculated for both models. There was a significant difference in the mean amount of bone reamed for the TMARS reconstructions (15,997 mm. 3. ) compared to the CTAC reconstructions (2292 mm. 3. , p>0.01). There was no significant difference between overall implant bone contact (TMARS 5760mm. 2. vs CTAC 5447mm. 2. , p=0.63). However, there was a significant difference for both cancellous (TMARS 4966mm. 2. vs CTAC 2887mm. 2. , p=0.008) and cortical bone contact (TMARS 795mm. 2. vs CTAC 2560mm. 2. , p=0.001). There was no difference in inclination and anteversion achieved. TMARS constructs resulted on average in a centre of rotations 7.4mm more lateral and 4.0mm more posterior. Modelling of two different reconstructions of Paprosky IIIB defects demonstrated potential important differences between all variables investigated

Aims. Custom flange acetabular components (CFACs) are a patient-specific option for addressing large acetabular defects at revision total hip arthroplasty (THA), but patient and implant characteristics that affect survivorship remain unknown. This study aimed to identify patient and design factors related to survivorship. Patients and Methods. A retrospective review of 91 patients who underwent revision THA using 96 CFACs was undertaken, comparing features between radiologically failed and successful cases. Patient characteristics (demographic, clinical, and radiological) and implant features (design characteristics and intraoperative features) were collected. There were 74 women and 22 men; their mean age was 62 years (31 to 85). The mean follow-up was 24.9 months (. sd. 27.6; 0 to 116). Two sets of statistical analyses were performed: 1) univariate analyses (Pearson’s chi-squared and independent-samples Student’s t-tests) for each feature; and 2) bivariable logistic regressions using features identified from a random forest analysis. Results. Radiological failure and revision rates were 23% and 12.5%, respectively. Revisions were undertaken at a mean of 25.1 months (. sd. 26.4) postoperatively. Patients with radiological failure were younger at the time of the initial procedure, were less likely to have a diagnosis of primary osteoarthritis (OA), were more likely to have had ischial screws in previous surgery, had fewer ischial screw holes in their CFAC design, and had more proximal ischial fixation. Random forest analysis identified the age of the patient and the number of locking and non-locking screws used for inclusion in subsequent bivariable logistic regression, but only age (odds ratio 0.93 per year) was found to be significant. Conclusion. We identified both patient and design features predictive of CFAC survivorship. We found a higher rate of failure in younger patients, those whose primary diagnosis was not OA, and those with more proximal ischial fixation or fewer ischial fixation options. Cite this article: Bone Joint J 2019;101-B(6 Supple B):68–76

We present the 10- to 17-year results of 112 computer-assisted design computer-assisted manufacture femoral components. The total hip replacements were performed between 1992 and 1998 in 111 patients, comprising 53 men and 58 women. Their mean age was 46.2 years (24.6 to 62.2) with a mean follow-up of 13 years (10 to 17). The mean Harris Hip Score improved from 42.4 (7 to 99) to 90.3 (38 to 100), the mean Oxford Hip Score from 43.1 (12 to 59) to 18.2 (12 to 51) and the mean Western Ontario MacMasters University Osteoarthritis Index score from 57.0 (7 to 96) to 11.9 (0 to 85). There was one revision due to failure of the acetabular component but no failures of the femoral component. There were no revisions for aseptic loosening. The worst-case survival in this cohort of custom femoral components at 13.2 years follow-up was 98.2% (95% confidence interval 95 to 99). Overall survival of this series of total hip replacements was 97.3% (95% confidence interval 95 to 99). These results are comparable with the best medium- to long-term results for femoral components used in primary total hip replacement with any means of fixation

Introduction. Custom flanged acetabular components (CFAC) have been shown to be effective in treating complex acetabular reconstructions in revision total hip arthroplasty (THA). However, the specific patient factors and CFAC design characteristics that affect the overall survivorship remain unclear. Once the surgeon opts to follow this treatment pathway, numerous decisions need to be made during the pre-operative design phase and during implantation, which may influence the ultimate success of CFAC. The goal of this study was to retrospectively review the entire cohort of CFAC cases performed at a large volume institution and to identify any patient, surgeon, or design factors that may be related to the long-term survival of these prostheses. Methods. We reviewed 96 CFAC cases performed in 91 patients between 2004 and 2017, from which 36 variables were collected spanning patient demographics, pre-operative clinical and radiographic features, intraoperative information, and implant design characteristics. Patient demographics and relevant clinical features were collected from individual medical records. Radiographic review included analysis of pre-operative radiographs, computer tomographic (CT) scans, and serial post-operative radiographs. Radiographic failure was defined as loosening or gross migration as determined by a board-certified orthopedic surgeon. CFAC implant design characteristics and intra-operative features were collected from the design record, surgical record and post-operative radiograph for each case respectively. Two sets of statistical analyses were performed with this dataset. First, univariate analyses were performed for each variable, comprising of a Pearson chi-square test for categorical variables and an independent t-test for continuous variables. Second, a random forest supervised machine learning method was applied to identify the most influential variables within the dataset, which were then used to perform a bivariable logistic regression to generate odds ratios. Statistical significance for this study was set at p < 0.05. Results. Radiographic failures occurred in 22/96 (23%) of cases with 12/96 (13%) undergoing re-revision (time to revision: Mean 25.1 months; Range: 3 – 84, SD 26.5). No relationship between radiographic failure and the preoperative Paprosky grade or the presence of a discontinuity was observed. The rate of radiographic failure (loosening and/or migration) was inversely associated with age, with increased failure seen in patients who were younger at the time of surgery; (mean age: 54.4±13.0 v. 64.8±11.4 years; p=0.007). Patients whose initial diagnosis was not osteoarthritis were more likely to fail than those with primary OA (OR: 3.79, p=0.0173) and were younger at the time of surgery (p=0.013). The presence of ischial screws from previous surgery (28%) was also an independent risk factor for failure (OR: 3.11, p=0.021). Random forest analysis identified the age at index procedure and the location of the inferior-most ischial screw as the most sensitive predictors of radiographic failure. As patient age at the time of surgery increased, there was subsequent a decreased rate of failure (OR: 0.93 odds ratio per year, p =0.005). When the bottom-most ischial screw was within the top half of the obturator foramen, it was 4 times more likely to fail than when this screw was located at the bottom half of the obturator foramen (OR = 3.98, p=0.046) (p < 0.05). Discussion and Conclusion. This study was able to identify the patient and design variables predictive of survival of CFAC prostheses used in complex revision THA. Younger patients (<55years) are at increased risk for failure either due to a more active lifestyle or because they have a non-OA primary diagnosis that predisposes them to earlier THA. Compromised ischial bone stock or inadequate ischial fixation both had a significant impact on CFAC implant survivorship as both the presence of pre-CFAC ischial screw fixation and lack of inferior ischial fixation correlated with increased rate of failure. These findings highlight the importance of rigid ischial fixation sufficient to resist the high pull-out forces generated during activities of daily living

Contemporary acetabular reconstruction in major acetabular bone loss often involves the use of porous metal augments, a cup-cage construct or custom implant. The aims of this study were: To determine the reproducibility of a reconstruction algorithm in major acetabular bone loss. To determine the subsequent success of reconstruction performed in terms of re-operation, all-cause revision and Oxford Hip Score (OHS) and to further define the indications for custom implants in major acetabular bone loss. Consecutive series of Paprosky Type III defects treated according to a reconstruction algorithm. IIIA defects were planned to use a superior augment and hemispherical cup. IIIB defects were planned to receive either augment and cup, cup-cage or custom implant. 105 procedures in cohort 100 patients (5 bilateral) with mean age 73 years (42–94). IIIA defects (50 cases) − 72.0% (95%CI 57.6–82.1) required a porous metal augment the remainder treated with a hemispherical cup alone. IIIB defects (55 cases) 71.7% (95%CI 57.6–82.1) required either augments or cup-cage. 20 patients required a hemispherical cup alone and 6 patients received a custom-made implant. Mean follow up of 7.6 years. 6 re-revisions were required (4 PJI, 2 peri-prosthetic fractures & 1 recurrent instability) with overall survivorship of 94.3% (95% CI 97.4–88.1) for all cause revision. Single event dislocations occurred in 3 other patients so overall dislocation rate 3.8%. Mean pre-op OHS 13.8 and mean follow-up OHS 29.8. Custom implants were used in: Mega-defects where AP diameter >80mm, complex discontinuity and massive bone loss in a small pelvis (i.e., unable to perform cup-cage). A reconstruction algorithm can >70% successfully predict revision construct which thereafter is durable with a low risk of re-operation. Jumbo cup utilized <1/3 of cases when morphology allowed. The use of custom implants has been well defined in this series and accounts for <5% of cases

Aims. Pelvic discontinuity is a rare but increasingly common complication of total hip arthroplasty (THA). This single-centre study evaluated the performance of custom-made triflange acetabular components in acetabular reconstruction with pelvic discontinuity by determining: 1) revision and overall implant survival rates; 2) discontinuity healing rate; and 3) Harris Hip Score (HHS). Methods. Retrospectively collected data of 38 patients (39 hips) with pelvic discontinuity treated with revision THA using a custom-made triflange acetabular component were analyzed. Minimum follow-up was two years (mean 5.1 years (2 to 11)). Results. There were eight subsequent surgical interventions. Two failures (5%) of the triflange acetabular components were both revised because of deep infection. There were seven (18%) patients with dislocation, and five (13%) of these were treated with a constraint liner. One patient had a debridement, antibiotics, and implant retention (DAIR) procedure. In 34 (92%) hips the custom-made triflange component was considered stable, with a healed pelvic discontinuity with no aseptic loosening at midterm follow-up. Mean HHS was 80.5 (48 to 96). Conclusion. The performance of the custom triflange implant in this study is encouraging, with high rates of discontinuity healing and osteointegration of the acetabular implant with no aseptic loosening at midterm follow-up. However, complications are not uncommon, particularly instability which we successfully addressed with constrained liners. Cite this article: Bone Jt Open 2022;3(11):867–876

Polymethylmethacrylate (PMMA) bone cement is strong in compression, however it tends to fail under torsion. Sufficient pressurisation and subsequent interdigitation between cement and bone are critical for the mechanical interlock of cemented orthopaedic implants, and an irregular surface on the acetabular cup is necessary for reasonable fixation at the cup-cement interface. There is limited literature investigating discrepancies in the failure mechanisms of cemented all-polyethylene acetabular cups with and without cement spacers, under torsional loading. In vitro experimental comparison of three groups of polyethylene acetabular prosthesis (PAP) cemented into prepared sawbone hemipelvises:. * PAP without PMMA spacers maintaining an equal cement mantle circumferentially. (Group 1 n=3). * PAP without PMMA spacers cemented deliberately ‘bottoming-out’ the implant within the acetabulum. (Group 2 n=3). * PAP with PMMA spacers. (Group 3 n=3). The constructs were tested to torstional failure on a custom designed setup, and statistical analysis done by a one-way ANOVA and Tukey-Welsh test. Group 3 demonstrated superior torsional resistance with a statistically significant torque of 145Nm (SD±12Nm) at failure, compared to group 2 (109Nm, SD±7Nm) and group 1 (99Nm, SD±8Nm). Group 3 experienced failure predominantly at the bone-cement interface, in contrast, Groups 1 and 2 exhibited failure predominantly at the cup-cement interface. There was no significant difference between Group 1 and 2. Qualitative analysis of the failure mode indicates the efficient redistribution of stress throughout the cement mantle, consistent with the greater uniformity of cement. PMMA spacers increase the resistance to torsional failure at the implant-cement interface. Acetabular components without spacers (Groups 1 and 2) failed at the implant-cement interface before the cement-bone interface, at a statistically significantly lower level of torque to failure. Although the PMMA spacers may reduce cement interdigitation at the cement-bone interface the torsional forces required to fail are likely supraphysiological

The benefits of total hip arthroplasty (THA) may be significantly magnified in children, since the improvement in quality of life has a far greater exposure time and occurs during key developmental stages which may help to maximise lifetime achievement. The purpose of this study is to describe implant survival and patient reported outcomes (PROMS) in a cohort of children following THA. Retrospective cohort review of all patients treated with THA in a single centre. Routine data analysis did not require ethical approval. Survival was estimated using Kaplan-Meier and PROMs were recorded (EQ5D-S, Oxford hip score and modified Harris Hip Score) in a sub-group of patients. 66 hips in 47 patients with a median age of 16 years (range 10 to 19 years) underwent THA between 1971 and 2023. 57% (38/68) patients were female, the commonest indications were Mucopolysaccharidoses n = 15, Stills disease (n=15), and Avascular necrosis (n=12). 27 (41%) of constructs were cemented, 5 (8%) were hybrid, and 34 (51%) were cementless. 30 stems were custom made cementless stems. Median follow up was 3.8 years (range 0–34 years). Implant survival was 87% at 10 years, 61.6% at 20 years and 52.8% at 30 years. PROMS demonstrated mean preoperative OHS was 12, preoperative MHHS was 23 and EQ5Ds VAS of 38. PROMS improved steadily overtime with mean OHS of 43, MMHS of 75 and EQ5Ds VAS of 89 at one year. THA was associated with a very large change in patient reported hip function and quality of life. In this study, THA delivered a long-lasting solution to hip pain with survival similar to that seen in patients undergoing THA in the fourth and fifth decades of life. Socioeconomic benefits of THA need further investigation to establish treatment guidelines for children suffering with hip pain

Genetic skeletal disorders constitute a rare and heterogeneous bone diseases often leading to poor quality of life. Several surgical options are available. The surgeon must deal with specific features (bone deformity, previous procedures, abnormal bone quality, stiffness or instability, muscle weakness). The questions concern the feasibility of the procedures and the surgical strategy. 55 patients (26 W, 29 M) were reviewed between 2016 and 2022. The mean age of the patients was 35 years (17–71). The diagnosis included 9 hereditary multiple exostoses, 8 osteogenesis imperfecta, 6 multiple epiphyseal dysplasia congenita, 6 achondroplasia, 4 osteopetrosis, 3 pycnodysostosis, 3 hypophosphatemic rickets, 3 fibrous dysplasia, 2 mucopolysaccharidosis, and 10 miscellaneous. 25 patients were referred for hip problems (40 hips). 4 patients (7 hips) requiring a THA have not been operated (4 planned). 4 patients (6 hips) had a proximal femoral fixation (2 osteotomies, 4 fracture fixations). 17 patients (27 hips) sustained a THA (25 primary, 2 revisions). All of them were operated by one operator, using a posterolateral approach and standard implants (including 7 dysplastic and 2 short stems). No customized implant has been used. As regard the 27 THAs, the mean follow up was 4.2 years (1–12). The early complications included 2 femoral cracks and 1 femur fracture. There were 2 revisions (1 cup loosening at 2 years, 1 stem loosening at 4 years). No infection nor dislocation occurred. All the patients were satisfied with their treatment and regain some autonomy. 3 THA were considered as unfeasible. Constitutional bone diseases need a multidisciplinary program of care. The indication for surgery is based on a mutual trust patient/surgeon, a careful evaluation of benefits/risks, and an accurate imaging to anticipate the difficulties. The expected results are a better function and quality of life, and a stability over time

Different techniques have been described to address massive bone loss of the acetabulum in revision hip surgery. aMace has gained popularity as it provides customization aiming to restore hip centre and provide good initial stability in cases of large non-contained defects. It takes into account quality of host bone. Its porous defect filling scaffold provides an excellent surface for osteointegration. Our aim was to assess the short and mid-term outcomes of patients who underwent revision surgery using aMace system. Ethical approval was obtained. A retrospective study included all patients who had aMace between June 2013 and October 2022 allowing for a minimum of 12-months follow-up. Patients’ demographics, indication, bone-loss severity, reconstruction details, re-operation, complications, mortality, pain and function were assessed. 52 cases were performed by 13 surgeons with median 51 months follow-up. Median age was 72.7 years. 86.5% were female. Average BMI was 25.3. Average ASA grade was 3. 65% were classified as Paprosky IIIB and 32% were IIIA. 73% were found to have poor bone quality on CT. Main indication for aMace was massive bone loss/discontinuity secondary to aseptic loosening in 88.5%. 77% underwent single-stage revision. 53.8% had 2 or more previous revisions. 71% underwent stem revision in the same setting. 77% received a dual mobility bearing. Re-operation rate was 5.7% for instability and femoral PPF. LLD was reported in 9.6%. Permanent Sciatic nerve palsy occurred in 3.8% of the cases. 30-days mortality was 1.9%. Statistically significant post-op improvements in pain and mobility were reported (p<0.001). None of the acetabular components have been revised. Our study shows satisfactory surgical outcomes with a relatively low complication rate and significant pain and mobility improvements in the early to mid-term stages. We recommend these costly cases to be done in highly specialist centres adopting MDT approach

Aims. The aim of this study was to examine the results of the acetabular distraction technique in achieving implantation of a stable construct, obtaining biological fixation, and producing healing of chronic pelvic discontinuity at revision total hip arthroplasty. Patients and Methods. We identified 32 patients treated between 2006 and 2013 who underwent acetabular revision for a chronic pelvic discontinuity using acetabular distraction, and who were radiographically evaluated at a mean of 62 months (25 to 160). Of these patients, 28 (87.5%) were female. The mean age at the time of revision was 67 years (44 to 86). The patients represented a continuous series drawn from two institutions that adhered to an identical operative technique. Results. Of the 32 patients, one patient required a revision for aseptic loosening, two patients had evidence of radiographic loosening but were not revised, and three patients had migration of the acetabular component into a more stable configuration. Radiographically, 22 (69%) of the cohort demonstrated healing of the discontinuity. The Kaplan–Meier construct survivorship was 83.3% when using revision for aseptic acetabular loosening as an endpoint. At the time when one patient failed due to aseptic loosening (at 7.4 years), there were a total of seven patients with a follow-up of seven years or longer who were at risk of failure. Conclusion. The acetabular distraction technique demonstrates encouraging radiographic outcomes, with healing of the discontinuity in over two-thirds of our series. This surgical technique permits biological fixation and intraoperative customization of the construct to be implanted based on the pattern of the bone loss identified following component removal. Cite this article: Bone Joint J 2018;100-B:909–14

Background. Ultraporous metals have now been used in acetabular reconstruction for two decades with excellent survival. The purpose of this study is to evaluate a newer porous metal made from Ti6Al4V titanium alloy in complex primary and revision hip arthroplasty. Methods. A retrospective review as performed on all total hip arthroplasty (THA) procedures in which a G7 Osseo-Ti (Zimmer Biomet, Warsaw, IN) acetabular component was used between 2015 and 2017. Patients with 2-year minimum follow-up or failure were included, yielding a cohort of 123 patients (126 hips). There were 50 male patients (41%; 51 hips) and 73 females (59%; 75 hips). Mean age was 65 years (range, 43–88) and mean BMI was 30.7 kg/m. 2. (range, 18–56). Indications for ultraporous metal components were in hips with compromised bone stock or severe acetabular deformity. Procedures were 35 complex primary THA and 91 revision THA that included 12 conversions and 24 reimplantations as part of 2-staged exchange for treatment of infection. Results. With an average 3.3-year follow-up (range, 2–5 years), 1 hip in the primary series (2.9%) and 4 hips in the revision series (4.4%) were revised for aseptic loosening of the acetabular component. Three of these re-revisions required custom triflange devices. Five patients (4%) failed for periprosthetic infection, which included 1 primary THA done for rheumatoid arthritis and post-radiation necrosis, and 4 second-stage reimplantation revision THAs for prior infection. Two revision patients, one done for active instability and one multiply revised, subsequently dislocated and required liner revision to constrained constructs. Kaplan-Meier analysis to endpoint of acetabular revision for aseptic loosening was 96.6% (±3.4%) in the primary series and 95.3% (±2.3%) in the revision series. Conclusion. This three-dimensionally printed ultraporous titanium acetabular component demonstrated promising early results in complex primary and revision total hip arthroplasty

Aims. Cementless acetabular components rely on press-fit fixation for initial stability. In certain cases, initial stability is more difficult to obtain (such as during revision). No current study evaluates how a surgeon’s impaction technique (mallet mass, mallet velocity, and number of strikes) may affect component fixation. This study seeks to answer the following research questions: 1) how does impaction technique affect a) bone strain generation and deterioration (and hence implant stability) and b) seating in different density bones?; and 2) can an impaction technique be recommended to minimize risk of implant loosening while ensuring seating of the acetabular component?. Methods. A custom drop tower was used to simulate surgical strikes seating acetabular components into synthetic bone. Strike velocity and drop mass were varied. Synthetic bone strain was measured using strain gauges and stability was assessed via push-out tests. Polar gap was measured using optical trackers. Results. A phenomenon of strain deterioration was identified if an excessive number of strikes was used to seat a component. This effect was most pronounced in low-density bone at high strike velocities. Polar gap was reduced with increasing strike mass and velocity. Conclusion. A high mallet mass with low strike velocity resulted in satisfactory implant stability and polar gap, while minimizing the risk of losing stability due to over-striking. Extreme caution not to over-strike must be exercised when using high velocity strikes in low-density bone for any mallet mass. Cite this article: Bone Joint Res 2020;9(7):386–393

Aims

The aim of this study was to examine the implant accuracy of custom-made partial pelvis replacements (PPRs) in revision total hip arthroplasty (rTHA). Custom-made implants offer an option to achieve a reconstruction in cases with severe acetabular bone loss. By analyzing implant deviation in CT and radiograph imaging and correlating early clinical complications, we aimed to optimize the usage of custom-made implants.

Aims

Large acetabular bone defects encountered in revision total hip arthroplasty (THA) are challenging to restore. Metal constructs for structural support are combined with bone graft materials for restoration. Autograft is restricted due to limited volume, and allogenic grafts have downsides including cost, availability, and operative processing. Bone graft substitutes (BGS) are an attractive alternative if they can demonstrate positive remodelling. One potential product is a biphasic injectable mixture (Cerament) that combines a fast-resorbing material (calcium sulphate) with the highly osteoconductive material hydroxyapatite. This study reviews the application of this biomaterial in large acetabular defects.

Aims

The aim of this study was to assess the clinical and radiological results of patients who were revised using a custom-made triflange acetabular component (CTAC) for component loosening and pelvic discontinuity (PD) after previous total hip arthroplasty (THA).