Uncemented acetabular component fixation remains the gold standard for managing various defects in the revision hip setting. Multiple series have demonstrated over 90% ten-year survivorship of these constructs. Modern “enhanced” metals such as trabecular tantalum and titanium continue to perform well and are growing in popularity. So called “jumbo” cups, diameters >=62mm in females and >=66mm in males have demonstrated excellent survivorship. Good bony support with viable bone and stable initial fixation is necessary for long-term success. It is unknown how much remaining bone is necessary for reliable ingrowth with modern enhanced metals. The location of the remaining bone is probably more important than the absolute amount remaining. Occasionally, the uncemented cup must be augmented with metal augments or even a so-called “cup cage” construct. Even in these situations, the uncemented cup remains the workhorse of revision THA due to its ingrowth potential and excellent track record. Augments are commercially available in various shapes and sizes to assist in the management of cavitary, segmental and combined defects while restoring the desired cup position. Trials are available to ensure good approximation of the augment to remaining bone. The constructs are typically “unitised” to the cup via bone cement. Available data show excellent survivorship of augmented constructs for these challenging reconstructions

Uncemented acetabular component fixation remains the gold standard for managing various defects in the revision hip setting. Multiple series have demonstrated over 90% ten-year survivorship of these constructs. Modern “enhanced” metals such as trabecular tantalum and titanium continue to perform well and are growing in popularity. So called “jumbo” cups, diameters >=62mm in females and >=66mm in males have demonstrated excellent survivorship. Good bony support with viable bone and stable initial fixation is necessary for long-term success. It is unknown how much remaining bone is necessary for reliable ingrowth with modern enhanced metals. The location of the remaining bone is probably more important than the absolute amount remaining. Occasionally, the uncemented cup must be augmented with metal augments or even a so-called “cup cage” construct. Even in these situations, the uncemented cup remains the workhorse of revision THA due to its ingrowth potential and excellent track record. Augments are commercially available in various shapes and sizes to assist in the management of cavitary, segmental and combined defects while restoring the desired cup position. Trials are available to ensure good approximation of the augment to remaining bone. The constructs are typically “unitised” to the cup via bone cement. Available data show excellent survivorship of augmented constructs for these challenging reconstructions

Introduction. Long term acetabular component fixation is dependent on bone ingrowth, which is affected by initial stability and the contact area between the bone and acetabular component. Mismatch between the component and cavity size has been shown to be one reason for component loosening. Furthermore, the potential of acetabular fracture during insertion of oversized components is larger than line-to-line components. An ideal cavity preparation would be a true hemispherical cavity that can provide maximum contact area between the shell and bone while also achieving adequate press fit for implant initial stability. The goal of this study was to characterize the cavity morphology produced by a commercially available reamer and compare it to a new reamer design. Materials & Methods. 36mm and 52mm reamers (n=6) were selected from conventional reamers (Stryker, Mahwah, NJ), which have successful clinical history exceeding 20 years, and Smooth Cut Reamers (Tecomet, Warsaw, IN and Stryker, Mahwah, NJ), which are a new design. Hemispherical cavities were created in 30 pcf polyurethane foam blocks (Pacific Research Laboratories, WA) using a custom software for the Mako System (Stryker, Mahwah, NJ), with new reamers of both designs. A reamer 2mm smaller in diameter than the final size was used to create a pilot cavity to replicate a clinically relevant reaming scenario. The resulting cavities were scanned using a Triple Scan high resolution 3D Scanner (ATOS, Purchase, NY) to generate 3D models of each cavity. The models were then post processed, and the following dimensions were collected:. Gaussian best fit spherical diameter of the entire cavity (Dimension A). Gaussian best fit diameter at the rim of the cavity (measured at a distance of 0.25mm from the top surface of the foam block) (Dimension B). One-sided two sample T-tests were conducted to determine statistical significance. Results. The deviation was calculated by subtracting the desired diameter from the observed diameter, therefore, a negative value would indicate an undersized cavity. The average diametrical deviation for the 38 and 52mm reamers for dimension A was −0.22 ± 0.07 and −0.01 ± 0.11 respectively for the Smooth Cut Reamer. The average diametrical deviation for the 38 and 52mm reamers for dimension A was −0.60 ± 0.24 and −0.72 ± 0.21 respectively for the Conventional Reamer. The average diametrical deviation for the 38 and 52mm reamers for dimension B was −0.97 ± 0.05 and −0.54 ± 0.11 respectively for the Smooth Cut Reamer. The average diametrical deviation for the 38 and 52mm reamers for dimension B was −1.35 ± 0.28 and −1.53 ± 0.27 respectively for the Conventional Reamer. Discussion. This study evaluated the accuracy of two different acetabular reamer designs. Results indicate that the Smooth Cut Reamers produce a cavity that is larger and more accurate to the indicated size of the reamer as shown by the reduced diametrical deviation at the rim (p-value < 0.05) and average spherical diameter (p-value < 0.05). Further investigation is warranted to determine if the variation in cavity geometry impacts shell seating and initial stability

Introduction. Successful cementless acetabular designs require sufficient initial stability between implant and bone (with interfacial motions <150 μm) and close opposition between the porous coating and the reamed bony surface of the acetabulum to obtaining bone ingrowth and secondary stability. While prior generations of cementless components showed good clinical results for long term fixation, modern designs continue to trend toward increased porosity and improved frictional characteristics to further enhance cup stability. Objectives. We intend to experimentally assess the differences in initial stability between a hemispherical acetabular component with a highly porous trabecular tantalum fixation surface (Continuum. ®. Acetabular System, Zimmer Inc, Warsaw, IN)(Fig 1) and a hemispherical component with the new highly porous Trabecular Titanium. ®. surface (Delta TT, Lima Corporate, Italy)(Fig 2) manufactured by electron beam melting. Material and methods. A total of 16 cups were used, 8 for each type. Each cup was used 4 times. Cups were implanted in polyurethane foam blocks with 1mm interference fit and subsequently edge loaded to failure. Two different foam block densities (0.24 g/cm. 3. and 0.32g/cm. 3. ) were used to model low- and high-density bone stock. Each cup was seated into a block under displacement control using a servohydraulic test machine (MTS Bionix 858, Eden Praire, MN) to engage the locking mechanism until axial forces reach 8 to 10 kN. During insertion, force and displacement were recorded to determine the implantation force for each component. After seating, initial acetabular component fixation was assessed using an edge loading test. Descriptive statistics are presented as means and standard deviations for continuous variables. The Kruskal-Wallis test was used to assess the effect of Cup on the outcomes: (1) Insertion force, (2) Insertion energy, (3) Ultimate load, (4) Yield load, and (5) Ultimate Energy. Pairwise comparisons were done using Mann-Whitney U test for significant outcomes and multiple comparisons were adjusted using Bonferroni correction. All analyses were performed with SAS version 9.3 (SAS Institute, Inc., Cary, NC, USA); a p-value less than 0.05 was considered statistically significant. Results. Delta TT cup required the same seating force (p=0.014) and 18% higher insertion energy (p=0.002) for fully seating compared to Continuum cup, however this difference is not clinically relevant. Delta TT cup exibithed more stability, as exibithed by significantly higher (35%) energy to ultimate load (p=0.014). No statistical differences were found in Ultimate load and Yield load among the 2 cups. Cups in higher density foam required higher force and energy to be seated. In edge load testing higher densities blocks generated higher force and energy accross all cup designs. Conclusions. The result of this study indicate increased interface stability in Trabecular Titanium cup compared to Porous tantalum cup with a low incresing in the energy required for fully seating

Purpose. To assess acetabular component fixation by bone ongrowth onto a titanium plasma sprayed surface as used in revision total hip arthroplasty. Acetabular bone defects, a common finding in revision surgery, and their relation to outcome were also investigated. Methods. Clinical and radiological results were evaluated for all revision total hip replacements done between 2006 and 2011 that included the use of a specific revision acetabular component. Forty six hips in 46 patients were followed for an average of 2.5 years (range8 months to 6 years). The acetabular defects were graded according to Paprosky's classification. Results. Two cups needed re-revision for aseptic loosening with a rate of repeat revision of 4% (2 of 46). Only one other (unrevised) cup showed radiographic signs of loosening at the last follow up. Acetabular defects were found to be Paprosky type I in 9, type IIA in 10, type IIB in 9, type IIC in 12, Type IIIA in 2 and type IIIB in 3. Screw fixation was necessary in 72% (33 of 46) to achieve intraoperative stability. Conclusion. This study demonstrated that bone ongrowth onto a titanium plasma sprayed surface can achieve stable fixation in acetabular revision in the presence of contained bone defects. Short to medium term follow-up shows satisfying results. It should however be used with caution where the area of contact with host bone is limited as found in Paprosky type IIIA, IIIB types and pelvic discontinuity. NO DISCLOSURES

Introduction. Adverse wear related failure (AWRF) after metal-on-metal hip resurfacing arthroplasty (HRA) has been described as a new failure mechanism. We describe the results of revision of these failures. Methods. Between July 1999 and Jan 2014, a single surgeon performed 3407 HRA. Nine (9/3407; 0.3%) cases in 8 patients were revised due to AWRF. In two additional revisions for AWRF the primary HRA was done elsewhere. There were a total of 11 revisions (9 women, 2 men) for AWRF cases reported in this study. The primary diagnoses were OA in 7 and dysplasia in 4. At the time of the primary surgery, the average age was 50±5 years and the average BMI was 27±4. The average femoral component sizes were 46±3mm. Only the acetabular component was revised in eight cases, both components were revised in 4 cases (revised to THA), three of these four used metal on metal bearings. A postop CT was requested for all patients after revision. 4 scans were of sufficient quality to analyze implant positions. Algorithms for metal artifact reduction were utilized to obtain high quality 2D images (Figure 1); 3D CAD models of the bones and implants were regenerated in order to calculate the acetabular inclination and anteversion angle (Figure 2). Results. Prior to revision, all 11 cases had acetabular inclination angles on standing radiographs (AIA) greater than 50° (mean 56. 0. range: 51°-60°) and Cobalt blood levels greater than 10ug/L (mean 94±64ug/L, range: 12–173 ug/L). Chromium levels were a mean of 50±33ug/L (range: 8–111 ug/L). 3D studies showed fluid collections and metalosis was seen in all cases. The mean follow-up length after revision was 2.4±1 years. In 4 cases the postop CT could be used to accurately measure implant positions resulting in a mean AIA=34°±9° and a mean anteversion angle of 18°±4°. Metal ion tests were available for 7 cases at least 1 year after revision. Cobalt levels were reduced to a mean of 4.1±3.1 ug/L (range: 1.5–6.2 ug/L) and Chromium levels fell to 6.3±2.9 ug/L (range: 3.4–10.9 ug/L). The mean HHS was 93±15. There was one failure of acetabular component fixation, which required repeat revision. Her latest HHS was 100 one year after the second surgery. For all revisions, the mean operative time was 123±15 min, incision length was 5±1 inches, estimated blood loss was 258±82 cc, and hospital stay was 1.3±0.5 days. There were no other major complications including no nerve palsies, vascular injuries or abductor mechanism disruptions. No patients limped. Conclusion. Our study suggests AWRF in HRA can successfully be revised with metal-on-metal surfaces. Revision of the femoral component is not necessary despite the abnormal wear. Correction of the steep AIA is the key to success. This confirms the concept that edge loading, leading to a high wear state, rather than allergy to metal is the cause of these failures

Objectives. Porous metal surfaces have been a popular option for acetabular component fixation in total hip arthroplasty (THA). New THA component designs are introduced periodically with the expectation of better wear properties and survivorship. Since its approval for use in 2002 there have been few clinical outcome studies published on the Pinnacle acetabular cup system. We hypothesised that the hemispherical porous coated Pinnacle acetabular cup system with a range of cup options and bearing surfaces would give us predictably good fixation and survivorship at five years post implantation. Materials and Methods. A total of 1391 Pinnacle acetabular cups (De Puy, a Johnson & Johnson company, Warsaw IN) were implanted between the period March 2003 to August 2011 by four senior surgeons. There were a total of 29 patients requiring revision surgery. Of these revisions, 23 were excluded from the final analysis. Sixteen were for early infection requiring debridement of the hip joint and exchange of the modular liner and femoral head. Five patients sustained femoral peri-prosthetic fractures requiring further surgery with retention of the acetabular component in all cases. Of the remaining 8 revision cases, only 6 had more than two years follow-up. All patients had pre and post-operative Harris hip scores, WOMAC and SF-12 scores. All patients were assessed with serial radiographs immediately post-operatively, 3 months, 1 year, 2 years, every 2 years thereafter. Component migration and revisions (excluding infection and peri-prosthetic fractures) are reported as failures. Post-operative radiographs were evaluated for component migration. Kaplan-Meier survivorship curves were drawn to show survivorship for cup type and bearing type. Results. A total of 894 Pinnacle acetabular components implanted into 796 patients were available for inclusion in the final analysis. There were 358 males with an average age of 63.70 years and 438 females with an average age of 64.55 years. The average period for follow-up was 44.95 months with 133 patients having more than five years of follow-up. Only one cup showed signs of aseptic loosening and component migration on plain radiographs, this patient had previously sustained an acetabular fracture requiring open reduction and internal fixation ans subsequently developed osteoarthritis. The cup failed to adequately in-grow and migrated medially to an intra-pelvic position, this was revised to a Trabelcular Metal cup with bone grafting to the acetabulum. There were two cases revised for instability. Three revisions were performed for aseptic loosening of the femoral components which were revised with retention of the acetabular cups. Conclusion. Published data on the performance of various porous coated cups have demonstrated varying degrees of osteolysis, however the Pinnacle cup has shown excellent midterm results postulated to be associated with the taper lock liner mechanism of the Pinnacle cups resulting in less micromotion and, therefore, reduced hydraulic pressure pumping polyethylene wear debris behind the cup. Our study confirms excellent overall survivorship of the Pinnacle acetabular porous coated cup system at a minimum of two years followup in over 790 patients

Introduction:. Uncemented acetabular component fixation has been considered the most reliable fixation method in contemporary metal-on-metal hip resurfacing arthroplasty (HRA). During prospective long-term follow-up of a HRA device, we have encountered a surprisingly high incidence of this complication and wish to alert surgeons and manufacturers of this problem. Methods:. The study group was comprised of all 373 HRAs performed by a single surgeon using this hybrid hip resurfacing implant from May 2001 to March 2005. The acetabular component features a dual-coated bone ingrowth surface of plasma-sprayed titanium plus hydroxylappatite. There were a total of 34 revisions identified at the time of this study. Results:. There were 5 other cases (1.3%) of late acetabular loosening all occurring greater than 8 years postoperatively at an average of 9 ± 1 years after the primary surgery. All of theses patients were functioning well with radiographically stable implants for at least 8 years. Intraoperative findings included debonding of large portions of the porous coating which remained adhered to the underlying bone. We concluded that these cases represented primary mechanical implant failures. There was a moderate amount of wear debris, presumably from the backside. There was no bone loss evident. There were no soft tissue masses. There were also 2 cases of adverse wear failure with pain and soft tissue masses diagnosed preoperatively with well-fixed implants. One of these patients also suffered component debonding prior to revision. Two (2/5; 40%) cases had an acetabular inclination angle ≥50°. Implant Debonding accounted for 5/8 (63%) of all acetabular failures and 14.7% (5/34) of all failures, while failure of ingrowth caused only 1/34 (3%) and adverse wear failures accounted for only 6% (2/34) of all failures. Conclusion:. We recommend that manufacturers re-evaluate the fixation strength of their own particular methods of bonding titanium plasma spray to a cobalt-chrome substrate, particularly in regards to fatigue failure and that they make improvements to ensure a longer duration of bone-implant fixation

Acetabular defects often result from osteolysis with or without component loosening. The goals of acetabular reconstruction in the face of significant rim or column deficiencies are to create a stable acetabular construct, which will facilitate acetabular component biologic fixation and long-term stability. Four reconstructive techniques have emerged to treat these defects: 1) Large allografts, 2) Cup / Cage constructs, 3) Metallic augments and uncemented hemispherical cups, and 4) Triflange custom implants. While all of these techniques have demonstrated success, we have elected to pursue triflange implants to improve fixation on host bone, allow modular liner options, facilitate enhanced fixation surfaces, match patient complex geometries, opportunity to utilise locking screws, and possibly reduce surgical operative time. Furthermore, screw paths and lengths can be planned pre-operatively along with custom pelvic model generation which makes surgical exposure and reconstructive more understandable. Multiple studies have shown excellent survivorship in series of the most challenging acetabular reconstructions