Objectives. In order to address acetabular defects, porous metal revision acetabular components and augments have been developed, which require fixation to each other. The fixation technique that results in the smallest relative movement between the components, as well as its influence on the primary stability with the host bone, have not previously been determined. Methods. A total of 18 composite hemipelvises with a Paprosky IIB defect were implanted using a porous titanium 56 mm multihole acetabular component and 1 cm augment. Each acetabular component and augment was affixed to the bone using two screws, while the method of fixation between the acetabular component and augment varied for the three groups of six hemipelvises: group S, screw fixation only; group SC, screw plus cement fixation; group C, cement fixation only. The implanted hemipelvises were cyclically loaded to three different loading maxima (0.5 kN, 0.9 kN, and 1.8 kN). Results. Screw fixation alone resulted in up to three times more movement (p = 0.006), especially when load was increased to 100% (p < 0.001), than with the other two fixation methods (C and SC). No significant difference was noted when a screw was added to the cement fixation. Increased load resulted in increased relative movement between the interfaces in all fixation methods (p < 0.001). Conclusion. Cement fixation between a porous titanium acetabular component and augment is associated with less relative movement than screw fixation alone for all implant interfaces, particularly with increasing loads. Adding a screw to the cement fixation did not offer any significant advantage. These results also show that the stability of the tested acetabular component/augment interface affects the stability of the construct that is affixed to the bone. Cite this article: N. A. Beckmann, R. G. Bitsch, M. Gondan, M. Schonhoff, S. Jaeger. Comparison of the stability of three fixation techniques between porous metal acetabular components and augments. Bone Joint Res 2018;7:282–288. DOI: 10.1302/2046-3758.74.BJR-2017-0198.R1

Reconstruction of massive acetabular bone defects in primary and revision THA is challenging for reconstructive joint surgeons. The use of porous metal augments is one of the options. The advantages of porous metal augments are easy to use, modularity and lack of resorption. We investigated the radiological results of porous metal augments used for massive acetabular bone defects in primary and revision THA. Forty-one hips in forty patients had porous metal augments between 2011 and 2016. Thirty of the procedures were revision arthroplasties and 11 were primary procedures (Crowe type III in 5 hips, Crowe type IV in 3, septic hip sequalae in 2 and RA in one). Four of the revisions were second-stage reimplantation after infection. The Paprosky classification for revision was 2B in 4 hips, 2C in one, 3A in 3 and 3B in 22. Regenerex augments were used in 39 hips and trabecular metal augments were used in 2. Thirty-six cups were cemented and 5 cups were uncemented. Mean follow-up was 37.6 months (range, 1–82). Radiographic findings of osteointegration between host bone and the porous metal augments were assessed. The presence or absence of radiolucent lines between cement or cup/host bone and augment/host bone interface was noted. Two revisions were performed due to infection, one month and 66 months after operation. The other implants were stable without any complications. Osteointegration between host bone and the porous metal augments were recognized in 36 hips. Radiolucent lines between cement/host bone interface, less than 1 mm in width, were visualized in 2 hips. Porous metal augments are convenient and our short-term results showed excellent radiological results for massive acetabular bone defects in primary and revision THA

This paper presents an ongoing review of the use of a wedge-shaped porous metal augments in the shoulder to address glenoid retroversion as part of anatomical total shoulder arthroplasty (aTSA). Seventy-five shoulders in 66 patients (23 women and 43 men, aged 42 to 85 years) with Walch grade B2 or C glenoids underwent porous metal glenoid augment (PMGA) insertion as part of aTSA. Patients received either a 15º or 30º PMGA wedge (secured by screws to the native glenoid) to correct excessive glenoid retroversion before a standard glenoid component was implanted using bone cement. Neither patient-specific guides nor navigation were used. Patients were prospectively assessed using shoulder functional assessments (Oxford Shoulder Score [OSS], American Shoulder and Elbow Standardized Shoulder Assessment Form [ASES], visual analogue scale [VAS] pain scores and forward elevation [FE]) preoperatively, at three, six, and 12 months, and yearly thereafter, with similar radiological surveillance. Forty-nine consecutive series shoulders had a follow-up of greater than 24 months, with a median follow-up of 48 months (range: 24–87 months). Median outcome scores improved for OSS (21 to 44), ASES (24 to 92), VAS (7 to 0), and FE (90º to 140º). Four patients died, but no others were lost to follow-up. Apart from one infection at 18 months postoperatively and one minor peg perforation, there were no complications, hardware failures, implant displacements, significant lucency or posterior re-subluxations. Radiographs showed good incorporation of the wedge augment with correction of glenoid retroversion from median 22º (13º to 46º) to 4º. All but four glenoids were corrected to within the target range (less than 10º retroversion). The porous metal wedge-shaped augments effectively addressed posterior glenoid deficiency as part of aTSA for rotator cuff intact osteoarthritis, producing satisfactory clinical outcomes with no signs of impending future failure

Cementless biologic fixation surfaces on total joint replacement devices, such as those used in total hip and knee procedures, have evolved over the decades. Historically, various surfaces to allow bone ingrowth or ongrowth have been applied as a coating to a pre-formed solid metal substrate. As shown in Figure 1, from left to right, representative coating surfaces include sintered beads, diffusion-bonded fiber metal, and plasma sprayed titanium. In certain applications, tantalum porous metal (Fig 1, left) can be used without a solid metal substrate, but its most widespread usage is in a modular acetabular cup design with the porous metal diffusion-bonded to a solid metal substrate similar to other coatings. Each of these examples of biologic fixation surfaces has limitations. With comparatively low porosity, bead, fiber metal and plasma spray coatings are simply a surface enhancement onto a rigid machined, forged or cast metal substrate. Furthermore, the thermal process to apply the coatings can adversely affect the mechanical properties of the metal substrate. Released in the 1990's, tantalum porous metal is considered a ‘highly porous metal’ with twice the porosity of the applied surface coatings. With that greater porosity comes lower strength that requires engineers to make standalone tantalum porous metal shapes more bulky. The chemical deposition process to produce tantalum porous metal shapes has also limitations on geometry possibilities. Where bonding the tantalum porous metal to a solid metal substrate is necessary for adequate strength, that diffusion bonding process pressure can diminish the surface coefficient of friction necessary for initial stability. A new class of manufacturing processing, referred to as ‘additive manufacturing’, allows engineers to create unique porous configurations. These configurations can be fabricated with beneficial properties to a specific implant application. One such enabling additive manufacturing process is called direct metal laser sintering (DMLS). This process utilizes a laser that travels over a fine powder bed. The laser path is determined by a program that mimics a computer model. Where the laser contacts the powder bed, the powder consolidates. Layer by layer, a scaffold porous metal is fabricated. Figure 2 shows a titanium alloy porous metal structure produced by DMLS. This formed biomaterial has 65% porosity, a high coefficient of friction, low stiffness, and strength that is 2 to 3 times that of tantalum porous metal. From a design versatility perspective, with greater strength, relatively thinner and more bone conserving geometries can be developed. When a solid metal surface interface to secure a modular polymer bearing is required, the DMLS process can produce the solid surface and the porous metal at the same time. With no secondary bonding thermal cycle needed, the construct's mechanical integrity is not compromised. Advancing biologic fixation necessitates bone conserving implant designs that have the properties to achieve immediate mechanical stability and longer term bone ingrowth. This novel use of DMLS in this particular porous metal geometry allows engineers to meet those criteria

Highly porous metal surfaces have transformed acetabular revision surgery by providing (1) enhanced friction which potentially provides greater primary fixation, (2) enhanced bone ingrowth potential, (3) enhanced screw fixation options. These characteristics have led many surgeons to use these devices routinely in acetabular revision and have led to an expansion of the indications for porous uncemented hemispherical cups in acetabular revision. Mid-term results suggest that the historical indications for hemispherical cups in revision surgery can be moderately expanded with some implants with these characteristics. In a recent study of 3448 revision total hip arthroplasties, we found porous tantalum cups had a statistically lower revision rate than other materials/designs. Highly porous metals also have provided the options of metal augments to fill selected bone defects—which can both enhance cup fixation and manage bone loss simultaneously. A number of different highly porous metals are now available, and how each will perform is not yet known

Failed ingrowth and subsequent separation of revision acetabular components from the inferior hemi-pelvis constitutes a primary mode of failure in revision total hip arthroplasty (THA). Few studies have highlighted other techniques than multiple screws and an ischial flange or hook of cages to reinforce the inferior fixation of the acetabular components, nor did any authors report the use of porous metal augments in the ischium and/or pubis to reinforce inferior fixation of the acetabular cup. The aims of this study were to introduce the concept of inferior extended fixation into the ischium and/or pubis during revision total hip arthroplasty, and to answer the following questions: (1) what are early clinical outcomes using inferior extended fixation and (2) what are the radiographic outcomes of hips revised with inferior extended fixation?. Patients who underwent revision THA utilizing the surgical technique of inferior extended fixation with porous metal augments secured in the ischium and/or pubis in a single institution from 2014 to 2016 were reviewed. Twenty-four patients were initially identified, and 16 patients were included based on the criteria of minimum 18 months clinical and radiographic follow-up. The median HHS, as well as the SF-12 physical and mental components improved significantly at the latest follow-up (p<0.001). The WOMAC global score decreased significantly at the latest follow-up (p<0.001). All constructs were considered to have obtained bone ingrowth fixation. Early follow-up of patients reconstructed with porous metal augments using the inferior extended fixation surgical technique demonstrated satisfactory clinical outcomes, restoration of the center of rotation and adequate biological fixation

Background. Failed ingrowth and subsequent separation of revision acetabular components from the inferior hemi-pelvis constitutes a primary mode of failure in revision total hip arthroplasty (THA). Few studies have highlighted other techniques than multiple screws and an ischial flange or hook of cages to reinforce the ischiopubic fixation of the acetabular components, nor did any authors report the use of porous metal augments in the ischium and/or pubis to reinforce ischiopubic fixation of the acetabular cup. The aims of this study were to introduce the concept of extended ischiopubic fixation into the ischium and/or pubis during revision total hip arthroplasty [Fig. 2], and to determine the early clinical outcomes and the radiographic outcomes of hips revised with inferior extended fixation. Methods. Patients who underwent revision THA utilizing the surgical technique of extended ischiopubic fixation with porous metal augments secured in the ischium and/or pubis in a single institution from 2014 to 2016 were reviewed. 16 patients were included based on the criteria of minimum 24 months clinical and radiographic follow-up. No patients were lost to follow-up. The median duration of follow-up for the overall population was 37.43 months. The patients' clinical results were assessed using the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and Short form (SF)-12 score and satisfaction level based on a scale with five levels at each office visit. All inpatient and outpatient records were examined for complications, including infection, intraoperative fracture, dislocation, postoperative nerve palsy, hematoma, wound complication and/or any subsequent reoperation(s). The vertical and horizontal distances of the center of rotation to the anatomic femoral head and the inclination and anteversion angle of the cup were measured on the preoperative and postoperative radiographs. All the postoperative plain radiographs were reviewed to assess the stability of the components. Results. At the most recent follow-up, 11 (68.8%) patients rated their satisfaction level as “very satisfied” and 4 (25.0%) were “satisfied.” The median HHS improved significantly and the WOMAC global score decreased significantly at the latest follow-up (? 0.001). No intraoperative or postoperative complications were identified. All constructs were considered to have obtained bone ingrowth fixation. The median vertical distance between the latest postoperative center of rotation to the anatomic center of the femoral head improved from 14.7±10.05 mm preoperatively to 6.77±9.14 mm at final follow-up (p=0.002). The median horizontal distance between the latest postoperative center of rotation to the anatomic center of femoral head improved from 6.3±12.07 mm laterally preoperatively to 2.18±6.98 mm medially at the most recent follow-up (p=0.013) postoperatively. The median acetabular cup abduction angle improved from 55.04°±10.11° preoperatively to 44.43°± 5.73° at the most recent follow-up postoperatively (p=0.001). However, there was no difference in the median cup anteversion angles preoperatively (9.15°±5.36°) to postoperatively (9.66°±3.97°) (P=0.535). Conclusions. Early follow-up of patients reconstructed with the technique of extended ischiopubic fixation with porous metal augments demonstrated satisfactory clinical outcomes, restoration of the center of rotation and adequate biological fixation. For any figures or tables, please contact the authors directly

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

Purpose: Porous metal technology may have significant impacts on implant fixation and long-term survival due to their high co-efficient of friction and similarity to trabecular bone in morphology and mechanical behaviour. While promising, the in vivo mechanical behaviour and micromotion at the interface has not previously been reported on. We report on the 2-year results of an RCT using radiosterometric analysis (RSA) to asses a porous metal (PM) monoblock tibial component. Method: Patients undergoing TKA were randomized to receive a either the PM (n=34) or the cemented tibial component (n=33). A standardized protocol was used for intra and post-operative factors. RSA exams were obtained postoperatively within 4 days of surgery and at 6, 12 and 24 months. One patient was excluded due to an intraoperative complication, and four others were lost to follow-up due to poor bead visibility or morbidity. Standard subjective outcome measures were applied. Results: There were no revisions in either group. The PM group exhibited two distinct migration patterns. One group stabilized immediately with similar migration to the cemented cases (0.38 vs. 0.46 p=0.4). A subset of 6 PM cases demonstrated significantly higher initial migration (mean=2.01mm, p< 0.01) but appeared stable at 2 years. In addition, 3 of the 6 high migration cases manifested independent bead subsidence. This was determined to be due to PM plate deformation. Two cemented cases were considered at risk for early failure due to aseptic loosening because of RSA migration pattern. There were no differences between groups in the subjective health outcome measures. Conclusion: A subset of PM components demonstrated high early migration followed by stabilization. It appears that some of these PM components deformed under load, most often in the posteromedial corner, perhaps as a result of malalignment or ligament imbalance. The implications of this finding are yet to be determined

Introduction. Cementless fixation in total knee arthroplasty has been proposed to offer advantages long-term once osteointegration has occurred as there is no substrate between the implant and the bone to fail. Radiostereometric analysis (RSA) is a useful tool to study fixation, but typically focused on early migration in the first two post-operative years. Few studies have looked at 10-year RSA migration in cementless fixation and those that have contain small numbers of subjects. The objective of this study was to compare implant migration and inducible displacement between cemented and cementless TKA at 10 years and to compare the 10-year migration to the 2-year data in an effort to validate the predictive modelling of RSA. Methods. Subjects who had previously participated in RSA migration studies with 2-year follow-up were recruited to return for a long-term follow-up exam, at least 10 years from their surgery. The implants under study included two cemented designs from two manufacturers and one porous metal monoblock cementless design. At the 10-year visit, subjects had supine RSA exams to determine long-term migration as well as a loaded exam (single leg stance) to determine inducible displacement. Differences between cemented and cementless groups were evaluated with the Mann Whitney U test and Spearman's rank correlation coefficients were calculated for early and late migrations. Significance was set at p < 0.05. Results. Seventy-five subjects were available for long-term follow-up, with average time since surgery of 12 years. This cohort contained 51 women and 24 men with cemented tibial components in 53 cases (37 female) and cementless tibial components in 22 cases (14 female). At the time of surgery, the subjects were 62±7 years old with BMIs of 33±6 m/kg2 (mean±standard deviation). Median migration at the long-term follow-up was 0.6 mm (MTPM; range 0.2–2.8 mm) and was not different between the cemented and cementless groups (p = 0.9, Mann Whitney U Test). Inducible displacement at 10 years was significantly lower for the cementless implants (p<0.001, Figure 1). Migration at one, two, and 10 years did not correlate with inducible displacement at 10 years. However, migration at one year and two years did correlate with long-term migration, with the strongest correlation at two years (Spearman's rank correlation coefficient for all components = 0.74, p < 0.001, Figure 2). Conclusion. Although long-term migration was not different for cemented or cementless (porous metal monoblock) tibial components, inducible displacement at the 10-year visit was significantly lower for these cementless components, suggesting superior fixation. Additionally, long-term migration was strongly correlated to two-year migration, regardless of fixation. These findings support the predictive value of short-term migration in determining long-term fixation. For any figures or tables, please contact authors directly

Metallosis is a combined chemical and toxic reaction which, if the wear of a metal implant is large, may cause extensive reaction of synovial membrane and thus triggering the loosening. We present a case of a 72 year-old man, who underwent to a cemented unicompartimental porous metal coated knee implant because affected by rheumatoid arthritis complicated by osteonecrosis of medial femoral condyle of the knee. Four years after replacement, the patient presented symptoms included moderate swelling, pain, synovitis inability to bear full weight as well as grinding; plain radiographs shows well fixed implant and not finding of loosening of prosthesis; arthroscopy revealed the diagnosis of metallosis. The specimens of synovial tissue were prepared to observation to light and electron microscopy. Total synovialectomy and revison with total knee replacement were successful in relieving the symptoms. Arthroscopy examination revealed a posterior break of tibial component, source of the release of multiple metal beads; we observe alsogray black discoloration of hypertofic and hyperplastic synovium pannus like; metal beads were detected in the joint space soft tissue and were also embedded in the articulating surface of the tibia component. Microscopic examination shows metal debris as black aggregates and a diffuse sheet like proliferation inside histiocytes of villous membrane. Ultrastructural study demonstrate that the presence of metallic fragments, measuring less than 0.3 micron in diameter is predominantly concentrated inside the macrophage’s phagolisosomes. Delivery of large number of metal beads from implant and the release of smallest size metal debris play a pivotal role in the development of a foreign body granulomatous reaction. The failure of unicompartimental prosthesis has been accellerated by unperformed sinoviectomy during the first implant; the cells of synovial membrane are continuosly activated, by wear of implant material, to phagocitate and to secrete inflammatory response

Advantages of cones in revision TKA

Reliable, Durable, Easy to do, Solves major problems (bone loss, fixation)

Bone loss in total knee replacement has different configurations and most condylar and plateau deficits are well managed with prosthetic augmentation. Cones are rarely, if ever, necessary for these deficits and when entire femoral condyles are absent distal segmental replacement has worked well. In the setting of severe intramedullary bone loss on the tibial or femoral side cones may be used to support deficit bone. This is the one indication for the use of cones.

The negative side of cones is that additional bone may be removed to fit a cone adequately. Many of the lesser areas of bone deficiency can be managed by the use of larger diameter stems for fixation. In a paper from Sandford et al. from the Vancouver group allograft results at 5 −10 year follow up had a similar success rate to cones. Rohl in a paper looking at cones and hybrid stems for bone loss in revision TKR found no difference in results at 3.5 years.

Cones cost $4,000–6,000 each and their utilization has been increasing greatly. At Hospital for Special Surgery in 2015 18 cones were used, this has increased to over 150 in 2017 at a cost of $800,000. The overutilization of cones adds considerably to the cost of a revision procedure. Cones have a place in revision TKR for bone loss but it is limited and they should be used in the most extreme cases where bone augmentation is required for structural stability.

Restoration of bone loss is a major challenge of revision TKA surgery. It is critical to achieve of a stable construct to support implants and achieve successful results. Major bone defects of the femoral and/or tibia (AORI type IIB/III) have been reconstructed using impaction grafting, structural allografts or tumor prostheses. The major concerns with structural allograft are graft resorption, mechanical failure, tissue availability, disease transmission, considerable surgical skill required and prolonged operative time. Porous tantalum metaphyseal cones, are becoming the established method of choice to correct large bone defects with several recent studies demonstrating promising results. The high coefficient of friction of these implants provides structural support for femoral and tibial components. The high degree of porosity has excellent potential for bone ingrowth and long-term biologic fixation. Several published series, although with relatively small cohorts of patients, have reported good short-term results with trabecular metal cones for major femoral and tibial bony defects in revision TKA. In a recent study, 16 femoral and 17 tibial cones were reviewed at an average follow up of 33 months (range, 13 to 73 months) the mean Knee Society Score improved from 42 pre-operatively to 83 at last follow up with an improvement of the functional score from an average of 34 to 66 (p<0.0001). Radiological follow up revealed no evidence of loosening or migration of the constructs. No evidence of complications were noted in correlation with the use of trabecular metal cones.

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 2 mm, then morsellised 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 TM cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There has been 4 cup loosenings with 3 re-revisions.

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.

Segmental defects of the acetabulum are often encountered in revision surgery. Many times these can be handled with hemispherical cups. However when larger defects are encountered particularly involving the dome and/or posterior wall structural support for the cup is often needed. In the past structural allograft was used but for the last 12 years at our institution trabecular metal augments have been used in the place of structural allograft in all cases. This talk will focus on technique and mid-term results using augments in association with an uncemented revision shell.

The technique can be broken down into 6 steps outlined below: 1. Exposure, 2. Reaming, 3. Trialing, 4. Augment Inserted, 5. Cup Insertion/Stabilization, 6. Trial Reduction/Liner Cementation

A recent study was undertaken to assess the mid-term results of this technique. We prospectively followed the first 56 patients in whom these augments were utilised in combination with a trabecular metal acetabular component in our unit. Details of this study will be presented.

The median follow up of the surviving patients was 110 months (range 88–128 months). Survivorship of the augments at 10 years was 92.2% (95% CI: 97.0–80.5%). In one case the augment was revised for infection and in 3 for loosening. In 1 of the revised cases there was a pre-operative pelvic discontinuity, the other 2 discontinuities in the series were not revised and remain asymptomatic.

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

Highly porous metal surfaces have transformed acetabular revision surgery by providing (1) enhanced friction which potentially provides greater primary fixation, (2) enhanced bone ingrowth potential, (3) enhanced screw fixation options. These characteristics have led many surgeons to use these devices routinely in acetabular revision and have led to an expansion of the indications for porous uncemented hemispherical cups in acetabular revision. Mid-term results suggest that the historical indications for hemispherical cups in revision surgery can be moderately expanded with some implants with these characteristics. In a recent study of 3448 revision total hip arthroplasties, we found porous tantalum cups had a statistically lower revision rate than other materials/designs. Highly porous metals also have provided the options of metal augments to fill selected bone defects—which can both enhance cup fixation and manage bone loss simultaneously. A number of different highly porous metals are now available, and how each will perform is not yet known. Highly porous metal shells may be used in combination with highly porous metal augments to make up for segmental bone deficiency. Examples will be shown. Finally, highly porous metal shells may be used as a “cup-cage” combination to provide extra initial cup mechanical stability in extreme cases. Examples will be shown

In primary total hip arthroplasty (THA) for patients with Crowe II or higher classes developmental dysplasia of the hip (DDH) or rapidly destructive coxopathy (RDC), the placement of the cup can be challenging due to superior and lateral acetabular bone defects. Traditionally, bone grafts from resected femoral heads were used to fill these defects, but bulk graft poses a risk of collapse, especially in DDH with hypoplastic femoral heads or in RDC where good quality bone is scarce. Recently, porous metal augments have shown promising outcomes in revision surgeries, yet reports on their efficacy in primary THA are limited. This study retrospectively evaluated 27 patients (30 hips) who underwent primary THA using cementless cups and porous titanium acetabular augments for DDH or RDC, with follow-up periods ranging from 2 to 10 years (average 4.1 years). The cohort included 22 females (24 hips) and 5 males (6 hips), with an average age of 67 years at the time of surgery. The findings at the final follow-up showed no radiographic evidence of loosening or radiolucency around the cups and augments, indicating successful biological fixation in all cases. Clinically, there was a significant improvement in the WOMAC score from an average of 39.1±14.7 preoperatively to 5.1±6.4 postoperatively. These results suggest that the use of cementless cups and porous titanium acetabular augments in primary THA for DDH and RDC can lead to high levels of clinical improvement and reliable biological fixation, indicating their potential as a viable solution for managing challenging acetabular defects in these conditions