Trabecular Titanium acetabular cups in hip revision surgery: mid-term clinical and radiological outcomes

Does Using Highly Porous Tantalum in Revision Total Hip Arthroplasty Reduce the Rate of Periprosthetic Joint Infection? A Systematic Review and Meta-Analysis

Background

Studies suggest tantalum (Ta) implants may have inherent antibacterial properties. However, there is no consensus regarding the effectiveness of Ta in preventing periprosthetic joint infection (PJI) after revision total hip arthroplasty (rTHA).

Methods

We searched 5 main databases for articles reporting the rate of PJI following rTHA using Ta implants from inception to February 2022. The PJI rates of the Ta group were meta-analyzed, compared with the control group, and represented as relative risks (RRs) in forest plots.

Results

We identified 67 eligible studies (28,414 joints) for assessing the prevalence of PJI following rTHA using Ta implants. Among these studies, only 9 compared the Ta implant group with a control group. The overall PJI rate following rTHA using Ta implants was 2.9% (95% confidence interval [CI]: 2.2%-3.8%), while it was 5.7% (95% CI = 4.1%-7.8%) if only septic revisions were considered. Comparing the Ta and control groups showed a significantly lower PJI rate following all-cause rTHA with an RR = 0.80 (95% CI = 0.65-0.98, P < .05). There was a trend toward lower reinfection rates in the Ta group after rTHA in septic cases, although the difference was not statistically significant (RR = 0.75, 95% CI = 0.44-1.29, P = .30).

Conclusions

Ta implants are associated with a lower PJI rate following all-cause rTHA but not after septic causes. Despite positive results, the clinical significance of Ta still remains unclear since the PJI rate was only reduced by 20%.

Level of Evidence

IV.

Early hip fracture surgery and rehabilitation. How to improve functional quality outcomes. A retrospective study

INTRODUCTION

Hip fractures are one of the major disability causes associated with a high morbidity and mortality rate. Early surgery and stable fixation could be associated with better pain control, possibly lower mortality rates, and early recovery of autonomy.

Biomedical Applications of Titanium Alloys: A Comprehensive Review

Titanium alloys have emerged as the most successful metallic material to ever be applied in the field of biomedical engineering. This comprehensive review covers the history of titanium in medicine, the properties of titanium and its alloys, the production technologies used to produce biomedical implants, and the most common uses for titanium and its alloys, ranging from orthopedic implants to dental prosthetics and cardiovascular devices. At the core of this success lies the combination of machinability, mechanical strength, biocompatibility, and corrosion resistance. This unique combination of useful traits has positioned titanium alloys as an indispensable material for biomedical engineering applications, enabling safer, more durable, and more efficient treatments for patients affected by various kinds of pathologies. This review takes an in-depth journey into the inherent properties that define titanium alloys and which of them are advantageous for biomedical use. It explores their production techniques and the fabrication methodologies that are utilized to machine them into their final shape. The biomedical applications of titanium alloys are then categorized and described in detail, focusing on which specific advantages titanium alloys are present when compared to other materials. This review not only captures the current state of the art, but also explores the future possibilities and limitations of titanium alloys applied in the biomedical field.

Forged to heal: The role of metallic cellular solids in bone tissue engineering

Metallic cellular solids, made of biocompatible alloys like titanium, stainless steel, or cobalt-chromium, have gained attention for their mechanical strength, reliability, and biocompatibility. These three-dimensional structures provide support and aid tissue regeneration in orthopedic implants, cardiovascular stents, and other tissue engineering cellular solids. The design and material chemistry of metallic cellular solids play crucial roles in their performance: factors such as porosity, pore size, and surface roughness influence nutrient transport, cell attachment, and mechanical stability, while their microstructure imparts strength, durability and flexibility. Various techniques, including additive manufacturing and conventional fabrication methods, are utilized for producing metallic biomedical cellular solids, each offering distinct advantages and drawbacks that must be considered for optimal design and manufacturing. The combination of mechanical properties and biocompatibility makes metallic cellular solids superior to their ceramic and polymeric counterparts in most load bearing applications, in particular under cyclic fatigue conditions, and more in general in application that require long term reliability. Although challenges remain, such as reducing the production times and the associated costs or increasing the array of available materials, metallic cellular solids showed excellent long-term reliability, with high survival rates even in long term follow-ups.

Extended trochanteric osteotomy is a safe procedure in two-stage hip revision: a systematic review of the literature

BACKGROUND

Extended trochanteric osteotomy (ETO) has proved to be an effective technique in complicated stem removal in femoral aseptic loosening or periprosthetic fracture. Debate remains about its safety in periprosthetic joint infection (PJI). The primary aim of this study is to analyze the ETO reinfection and union rate in two-stage hip revision.

MATERIAL AND METHODS

A systematic literature review was performed regarding all studies reporting ETO outcomes in the two-stage revision for hip PJI up to October 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. A literature search was conducted in the following databases: MEDLINE/EMBASE, Scopus, Web of Science, and Cochrane. Quality assessment of the articles was performed using the Methodological Index for Non-Randomized Studies. This systematic review was registered in the International Prospective Registry of Systematic Reviews. Patient demographic, clinical, and surgical data were collected.

RESULTS

This systematic review included and analyzed nine clinical studies with a total of 382 ETO PJI hips in two-stage revision. The overall ETO reinfection rate was 8.9% (34 hips), consistent with the reinfection rate after two-stage revision in patients without ETO. The overall ETO union rate was 94.8% (347 hips), comparable to the ETO union rate in non-septic patients. Compared between a group of patients with ETO PJI and a group of patients with non-PJI ETO, there were no significant differences in postoperative complications, both septic and aseptic, and for postoperative HHS.

CONCLUSION

ETO proved to be a safe and effective procedure in PJI revisions. It may be a viable option in challenging femoral stem removal during the two-stage hip revision in PJI.

LEVEL OF EVIDENCE

IV.

Trabecular titanium implants in complex acetabular revision surgery

INTRODUCTION

Acetabular revision surgery is a surgical challenge, especially when complex bone defects appear. This makes primary fixation and osseointegration of the implants difficult, which conditions the appearance of complications. Trabecular titanium implants attempt to solve these problems.

OBJECTIVES

To evaluate our clinical-radiological results, the survival of the implants and the appearance of mid-term complications in acetabular revision surgery in a series of 37 acetabular replacements with Paprosky type IIIA and IIIB bone defects in which a trabecular titanium Cup-Cage revision implant was used.

MATERIAL AND METHOD

We conducted an observational, descriptive and retrospective study of 37 cases with complex acetabular defects (20 type IIIA and 17 type IIIB, five of them with pelvic discontinuity) in which the acetabular component was replaced by trabecular titanium cups between 2011 and 2019. We analyzed clinical results (pain and functionality) and radiological parameters (restoration of the hip rotation centre and the mobilization of the implants), as well as the appearance of complications.

RESULTS

The mean follow-up was 61 months. We obtained a median improvement of 8 points on the Merlé D'Aubigné-Postel functionality scale and 6 points on the VAS scale of pain perceived by the patient. We recorded two cases of acetabular loosening, one case of dislocation and three surgical wound infections without affecting the implant.

CONCLUSIONS

The use of trabecular titanium Cup-Cage implants could be a valid option in acetabular revision surgery with complex acetabular defects, presenting good clinical and radiological results and in terms of complications and survival of the implants, mainly due to their good primary fixation and subsequent osseointegration.

[Translated article] Trabecular titanium implants in complex acetabular revision surgery

INTRODUCTION

Acetabular revision surgery is a surgical challenge, especially when complex bone defects appear. This makes primary fixation and osseointegration of the implants difficult, which conditions the appearance of complications. Trabecular titanium implants attempt to solve these problems.

OBJECTIVES

To evaluate our clinical-radiological results, the survival of the implants and the appearance of mid-term complications in acetabular revision surgery in a series of 37 acetabular replacements with Paprosky type IIIA and IIIB bone defects in which a trabecular titanium Cup-Cage revision implant was used.

MATERIAL AND METHOD

We conducted an observational, descriptive and retrospective study of 37 cases with complex acetabular defects (20 type IIIA and 17 type IIIB, five of them with pelvic discontinuity) in which the acetabular component was replaced by trabecular titanium cups between 2011 and 2019. We analysed clinical results (pain and functionality) and radiological parameters (restoration of the hip rotation centre and the mobilisation of the implants), as well as the appearance of complications.

RESULTS

The mean follow-up was 61 months. We obtained a median improvement of 8 points on the Merlé D'Aubigné-Postel functionality scale and 6 points on the VAS scale of pain perceived by the patient. We recorded two cases of acetabular loosening, one case of dislocation and three surgical wound infections without affecting the implant.

CONCLUSIONS

The use of trabecular titanium Cup-Cage implants could be a valid option in acetabular revision surgery with complex acetabular defects, presenting good clinical and radiological results and in terms of complications and survival of the implants, mainly due to their good primary fixation and subsequent osseointegration.

Custom-made 3D-printed porous metal acetabular composite component in revision hip arthroplasty with Paprosky type III acetabular defects: A case report

BACKGROUND

Increases in the numbers of surgical procedures for primary total hip arthroplasty (THA) inevitably lead to increases in the requirements for revision THA. The achievement of long-term stability is difficult or impossible by conventional implants in patients with severe destruction of the acetabulum.

OBJECTIVE

This case report presents a successful treatment using a specific three-dimensional (3D)-printed porous titanium acetabular composite component without a flange in the management of Paprosky type IIIB acetabular defects.

METHOD

A 65-year-old female diagnosed with right hip prosthetic loosening with a huge acetabular defect presented to our hospital. We designed the 3D model of the pelvis and created an individualized 3D-printed porous titanium acetabular composite component for revision THA. The procedure was performed through a posterolateral approach, and the component was implanted in the defect and fixed with cup screws using the drill guides.

RESULTS

At the last follow-up at 2 years, the patient had a satisfactory hip joint function and no signs of loosening or other complications were found.

CONCLUSIONS

The 3D-printed porous titanium acetabular composite component without a flange is showing promising clinical and radiological outcomes in the management of Paprosky type III acetabular defects.

Acetabular revision using trabecular titanium (Delta TT) revision cups: A retrospective case series

BACKGROUND

The annual rate of primary THA has been increasing with new designs promoting THA in the younger population, therefore increasing rates and complexity of hip revision surgeries. Different types of acetabular defects in hip revisions, usually make the use of primary cementless cups quite difficult. In complex defects, using cages with cemented cups or combining cementless cups with metal augments, are possible reconstruction solutions. The Delta TT acetabular revision system provides a solution to complex defects combining the advantages of both cage construct and primary implants, with modularity that helps restore anatomical hip centre and biomechanics. The aim of this study is to evaluate the short-term results of the use of the Delta TT revision system in acetabular revision surgeries.

TYPE OF THE STUDY

A retrospective case series.

METHODS

24 patients underwent acetabular revision using (Delta TT) revision system, from 2018 to 2021. The mean follow-up was 20.75 months. Clinical and functional outcomes were assessed using Harris Hip Score.

RESULTS

The use of the Delta TT revision system in acetabular revision surgery provided adequate pain relief, and early patient mobilization. The preoperative HHS mean of 29.88 improved to a mean of 85.21, at the last, follow-up. None of the patients developed periprosthetic infection or loosening or nerve palsy during the follow-up period.

CONCLUSION

Short-term clinical outcomes for the use of the Delta TT revision cup system in acetabular revision are encouraging with good functional outcomes and patient satisfaction.

Clinical and radiological outcomes of total hip arthroplasty in octogenarian patients using a three-dimensional porous titanium cup: a retrospective analysis in Japanese patients

PURPOSE

Osteointegration of a three-dimensional (3D) porous titanium material has been experimentally proven, but only a few studies have shown the clinical outcomes of a 3D porous titanium cup in the Japanese elderly population. The purpose of this study was to compare the short-and-medium term clinical and radiographic results of total hip arthroplasty (THA) using a 3D porous titanium cup in patients aged ≥ 80 (octogenarians) versus those aged < 80 (younger controls).

METHODS

A total of 104 hips that underwent THA using a 3D porous titanium cup (SQRUM TT, Kyocera Medical) were enrolled in the study and were divided into two groups according to age: the octogenarian group (≥ 80, n = 42) and the younger control group (< 80, n = 62). Furthermore, we evaluated patient characteristics, clinical outcomes determined by the Japanese Orthopedic Association score, cup alignment, and incidence of radiolucent lines around the cup.

RESULTS

The mean follow-up period was 4.2 and 4.0 years (p = 0.29) for octogenarians and younger controls, respectively. The clinical outcomes were excellent, and no revision surgery occurred until the last follow-up in both groups. The number of patients with radiolucent lines at the final evaluation was 21 of 62 (33.9%) in younger controls and 16 of 42 (38.1%) in octogenarians.

CONCLUSION

THA with 3D porous titanium cup for octogenarians had similar clinical outcomes and incidence of radiolucent lines as those of younger controls, suggesting that the 3D porous titanium cup may be useful in THA for octogenarians. Further investigations will confirm its long-term outcomes.

Trabecular titanium cups in acetabular revision arthroplasty: analysis of 10-year survivorship, restoration of center of rotation and osteointegration

AIMS

In case of severe bone loss, acetabular revision can be challenged using extra porous pure trabecular titanium (TT) revision cups designed to ensure enhanced iliac and ischiatic purchase. Aim of the study is to report on the clinical and radiological results of a TT acetabular component, evaluating functional outcome, restoration of the hip center of rotation and osteointegration.

METHODS

85 patients, who underwent acetabular revision with a TT revision cup system between October 2009 and December 2018, were included in a retrospective study. Clinical outcome were assessed with Harris Hip Score (HHS). The hip rotation center was measured using the Pierchon method on the AP pelvis film. Loosening of the cup was determined according to the Kosashvili modification of Gill's criteria. Kaplan- Meier survivorship curve was performed. Results The mean follow-up was 6.12 years. The average HHS improved from 54.7 points to 89.7 points (p < 0.05). Two acetabular components (2.3%) were re-revised after a mean of 5.6 years, for aseptic loosening and for infection, with a progressive radiolucency and a > 5 mm vertical migration, respectively. The radiographic evaluation of the position of the hip rotation center revealed a statistically significant difference (p < 0.05) between the pre- and post-operative values. The hip rotation center was correctly restored within 5% of the reference Pierchon values in a percentage of 85.4% relative to horizontal parameters and within 8% in a percentage of 66.7% relative to vertical parameters. 5-year and 10-year survivorships were, respectively, 100% and 88%.

CONCLUSIONS

In case of severe bone loss, TT revision cup system allows for good restoration of center of rotation and osteointegration showing good 10-year survival rate.

Trabecular metal augments in severe malignancy-associated acetabular bone loss

INTRODUCTION

Acetabular reconstruction is a challenging problem in orthopaedic oncology, especially in extended defects (Paprosky Type 3A and Type 3B). In revision total hip arthroplasty (THA), 1 option is trabecular metal (TM) augments with a porous metal acetabular component. This study evaluated the use of TM augments in periacetabular malignant bone disease.

METHODS

15 patients were identified from our institutional database from 2000 to 2020 with either Paprosky Type 3A or Type 3B acetabular bone loss due to periacetabular malignancies that underwent at least 1 complex THA reconstruction with TM augments. Postoperative complications were documented, and clinical and radiographic outcomes were analysed. Radiological loosening or revision of the acetabular component were defined as endpoints.

RESULTS

There were 7 primary and 8 metastatic cancer patients. 5 were Type 3A and 10 were Type 3B defects after tumour resection. The average follow-up time was 23.8 (range 1.5-47) months. 1 patient required revision for acetabular component loosening after 7 months from the initial implantation. An additional 4 patients required surgical intervention for infection, they had stable TM augments at latest follow-up.

CONCLUSION

TM augments with a porous metal acetabular component may be an alternative to the traditional cemented constructs.

Use of a new off-the-shelf 3D-printed trabecular titanium acetabular cup in Chinese patients undergoing hip revision surgery: Short- to mid-term clinical and radiological outcomes

Background

Revision total hip arthroplasty (THA) has been a challenge for surgeons. The purpose of this study was to explore the short-to mid-term clinical and radiological outcomes of Chinese patients who underwent revision THA using a new off-the-shelf three-dimensional (3D)-printed trabecular titanium (TT) acetabular cup by comparison with a conventional porous coated titanium acetabular cup, to provide a reference for the recommendation of this prostheses.

Methods

A retrospective analysis of 57 patients (57 hips) who received revision THA was performed from January 2016 to June 2019. A total of 23 patients received 3D-printed cups (observation group) and 34 patients received non-3D-printed cups (control group). Clinical scores including Visual Analogue Scale (VAS), Harris Hip Score (HHS) and Short Form 36 (SF-36), upward movement of the hip center of rotation(HCOR)and limb-length discrepancy (LLD), stabilization and bone ingrowth of cups were compared between two groups. The multivariate linear regression was used to determine the factors potentially influencing the HHS score. Postoperative complications in the two groups were also recorded.

Results

All 57 patients were routinely followed up. The average follow-up durations in the control and observation groups were 43.57 ± 13.68 (24–65) months and 41.82 ± 11.44 (24–64) months, respectively (p = 0.618). The postoperative clinical scores significantly improved in both groups compared to the preoperative scores (p < 0.001). The VAS score did not significantly differ between the groups at 3 (p = 0.946) or 12 (p = 0.681) months postoperatively, or at the last follow-up (p = 0.885). The HHS score did not significantly differ between the groups at 3 months (p = 0.378) postoperatively but differed at 12 months (p < 0.001) postoperatively and the last follow-up (p < 0.001). The SF-36 score did not significantly differ between the groups at 3 months (p = 0.289) postoperatively, but was significantly different at 12 months (p < 0.001) postoperatively and the last follow-up (p < 0.001). Compared with the control group, the postoperative recovery of HCOR and LLD was better in the observation group. All cups remained stable, with no loosening throughout the follow-up period. But the observation group had a significantly better rate of bone ingrowth compared to the control group (p = 0.037). Multivariate linear regression analysis showed that different cup types, upward movement of the HCOR, and LLD influenced the HHS score at the last follow-up (p < 0.001, p = 0.005, respectively). None of the patients exhibited severe postoperative complications.

Conclusion

The new off-the-shelf 3D-printed TT acetabular cup demonstrated encouraging short-to mid-term clinical outcomes in Chinese patients. It can effectively relieve pain, improve hip function, provide satisfactory biological fixation and high survival rate. But further follow up is necessary to assess its long-term outcomes.

[Use of custom-made acetabular components (CMAC) as part of a two-stage procedure in patients with severe periacetabular bone loss]

OBJECTIVE

Implantation of custom-made acetabular components (CMAC) with load transmission onto the remaining bone stock and reconstruction of the "center of rotation" (COR) in cases of severe periacetabular bone defects.

INDICATIONS

Severe periacetabular bone loss (Paprosky type IIIA/B) with or without pelvic discontinuity after septic or aseptic loosening with inadequate load capacity of the dorsal pillar and/or large supraacetabular defects.

CONTRAINDICATIONS

Acute or local infections, lack of compliance, taking into account the risks and complications: missing or limited expected postoperative functional gain, multimorbid patients with potential inoperability during the first and/or second intervention.

SURGICAL TECHNIQUE

Lateral transgluteal or posterolateral approach while protecting neurovascular and muscular structures. Preparation of the implant site based on preoperative planning with augmentation of bone defects as far as possible. Primarily stable anchoring with 2 angle-stable pole screws in the ilium, an optional pole screw in the pubic bone for determination of COR, and stabilization screws in the iliac wing (optionally angle-stable). Use of dual mobility cup according to the soft tissue tension and intraoperative stability.

POSTOPERATIVE MANAGEMENT

For the first 6 weeks postoperative partial weight-bearing (20 kg), followed by a gradual increase of the load (10 kg per week).

RESULTS

Between 2008 and 2018, 47 patients with a Paprosky type III defect underwent implantation of a monoflanged CMAC. Main complication was a periprosthetic joint infection with subsequent need for implant removal in 9 of 10 cases. Harris Hip Score improved from 21.1 to 61.5 points. X‑ray imaging displayed an angle of inclination of 42.3 ± 5.3°, an anteversion of 16.8 ± 6.2°, a ∆ H of 0.5 ± 0.2 mm and a ∆ V of 17.7 ± 1.1 mm according to Roessler et al.

Pelvic discontinuity: a challenge to overcome

Pelvic discontinuity (PD) has been a considerable challenge for the hip revision arthroplasty surgeon. However, not all PDs are the same. Some occur during primary cup insertion, resembling a fresh periprosthetic fracture that separates the superior and inferior portions of the pelvis, while others are chronic as a result of gradual acetabular bone loss due to osteolysis and/or acetabular implant loosening.In the past, ORIF, various types of cages, bone grafts and bone cement were utilized with little success. Today, the biomechanics and biology of PD as well as new diagnostic tools and especially a variety of new implants and techniques are available to hip revision surgeons. Ultraporous cups and augments, cup-cage constructs and custom triflange components have revolutionized the treatment of PD when used in various combinations with ORIF and bone grafts. For chronic PD the cup-cage construct is the most popular method of reconstruction with good medium-term results.Dislocation continues to be the leading cause of failure in all situations, followed by infection. Ultimately, surgeons today have a big enough armamentarium to select the best treatment approach. Case individualization, personal experience and improvisation are the best assets to drive treatment decisions and strategies. Cite this article: EFORT Open Rev 2021;6:459-471. DOI: 10.1302/2058-5241.6.210022.

Total hip arthroplasty using a three-dimensional porous titanium acetabular cup: an examination of micromotion using subject-specific finite element analysis

Background

We investigated the mid-term clinical and radiological results of total hip arthroplasty (THA) using a three-dimensional (3D) porous titanium cup and analyzed the micromotion at the interface of the cup using subject-specific finite element (FE) analysis.

Methods

We evaluated 73 hips of 65 patients (6 men and 59 women; mean age at the time of surgery, 62.2 years; range, 45–86 years) who had undergone THA using a 3D porous titanium cup. Clinical evaluations were performed using the Japanese Orthopaedic Association (JOA) hip score system. We assessed the fixation of the acetabular component based on the presence of radiolucent lines and cup migration using anteroposterior radiographs. Subject-specific FE models were constructed from computed tomography data.

Results

The JOA score improved from a preoperative mean of 52.2 (range, 23–82) to a mean of 87.8 (range, 71–100) at the final follow-up. None of the patients underwent revisions during the follow-up period. Radiolucent lines were observed in 26 cases (35.6%) and frequently appeared at DeLee and Charnley Zone 3. Following the FE analysis, the micromotion at DeLee and Charnley Zone 3 was significantly larger than that at Zone 2. Furthermore, micromotion was large in the groups in which radiolucent lines appeared at Zone 3.

Conclusions

The mid-term clinical outcome of THA using a 3D porous titanium cup was excellent. However, radiolucent lines frequently appeared at DeLee and Charnley Zone 3. FE analysis indicated that micromotion was large at the same site, strongly suggesting that it contributes to the emergence of radiolucent lines. The 3D porous titanium cups are useful in THA, and with improvements focused on micromotion, we anticipate better long-term outcomes.

Clinical and radiological outcomes of acetabular revision surgery with trabecular titanium cups in Paprosky type II and III bone defects

BACKGROUND

This prospective study aims to evaluate the mid-term clinical outcomes and radiographic stability of two different types of cementless trabecular titanium acetabular components in total hip revision surgery.

METHODS

Between December 2008 and February 2017, 104 cup revisions were performed using trabecular titanium revision cups. Mean age of patients was 70 (range 29-90; SD 11) years. The majority of revisions were performed for aseptic loosening (86 cases, 82.69%), but in all the other diagnoses (18 cases), a significant bone loss (Paprosky type II or III) was registered preoperatively. Bone defects were classified according to Paprosky acetabular classification. We observed 53 type II defects and 42 type III defects. Cups were chosen according to the type of defect.

RESULTS

Average follow-up was 91 (range 24-146) months. Mean Harris Hip Score (HHS) improved from 43.7 (range 25-70; SD 9) preoperatively to 84.4 (range 46-99; SD 7.56) at last follow-up. One (1.05%) cup showed radiographic radiolucent lines inferior to 2 mm and was clinically asymptomatic. One (1.05%) cup was loose and showed periacetabular allograft reabsorption. Kaplan-Meier survivorship was assessed to be 88.54% (95% CI 80.18-93.52%) at 71 months, with failure of the cup for any reason as the endpoint.

CONCLUSION

Trabecular titanium revision cups showed good clinical and radiographic results at mid-term follow-up in Paprosky type II and III bone defects.

LEVEL OF EVIDENCE

Level IV prospective case series.

A new 3D printing porous trabecular titanium metal acetabular cup for primary total hip arthroplasty: a minimum 2-year follow-up of 92 consecutive patients

Background

Aseptic cup loosening is still one of the main reasons leading to acetabular cup failures. 3D printing porous trabecular titanium metal acetabular cup may provide good initial stability and secondary fixation because of its highly interconnected, porous structure. Few large sample studies have reported the clinical outcomes of electron beam melting (EBM) porous titanium acetabular cup in Chinese population.

Methods

We retrospectively collected and analyzed the clinical data of a total of 92 consecutive patients between January 2013 and November 2017, with an average follow-up of 48.2 ± 3.6 months. Clinical outcomes included Harris Hip Score (HHS), the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index, satisfaction rate, and cup survival rate were evaluated. Radiographic assessments were conducted to evaluate osteointegration.

Results

HHS scores improved significantly while the WOMAC score decreased significantly at the latest follow-up (p < 0.001). The satisfaction rate (prevalence of satisfied or very satisfied) was 91.3%. No acetabular cup failures occurred. Radiolucent lines appeared in 15 cases (18 hips) and disappeared in 6 months. No cup loosening signs found until the last follow-up. The overall survival rate of implantation is 99.1% (cup survival rate 100%).

Conclusion

The new EBM-produced 3D ACT™ cup demonstrated us its favorable short- to mid-term clinical outcomes in Chinese THA patients. It can provide high acetabular cup survival rate, great clinical improvements and excellent biological fixation. Further investigations are needed to confirm its long-term outcomes.

Highly Porous Titanium Acetabular Components in Primary and Revision Total Hip Arthroplasty: A Systematic Review

BACKGROUND

A number of papers have been published reporting on the clinical performance of highly porous coated titanium acetabular cups in primary and revision total hip arthroplasty (THA). However, no systematic review of the literature has been published to date.

METHODS

The US National Library of Medicine (PubMed/MEDLINE), Embase, and the Cochrane Database of Systematic Reviews were queried for publications utilizing the following keywords: "tritanium" OR "highly-porous" AND "titanium" OR "acetabular" AND "trabecular" AND "titanium".

RESULTS

Overall, 16 studies were included in this review (11,366 cases; 60% females, 2-7 years mean follow-up). The overall survival rate of highly porous titanium acetabular components in primary cases was 99.3% (10,811 of 10,886 cases), whereas the rate of aseptic loosening was 0.1%. The overall survival rate of the highly porous titanium acetabular components in revision THA cases was 93.5% (449 of 480 cases), whereas the rate of aseptic loosening was 2.1%.

CONCLUSION

There was moderate quality evidence to show that the use of highly porous titanium acetabular components in primary and revision THA cases is associated with satisfactory clinical outcomes in the short- and medium-term, without showing any evidence of cup migration or radiolucency. Taking into consideration that there is no evidence yet regarding the long-term survivorship of these components, we feel that further research of higher quality is required to generate more evidence-based conclusions regarding the longevity of highly porous titanium acetabular implants compared with conventional titanium counterparts.

Characterization of dimensional, morphological and morphometric features of retrieved 3D-printed acetabular cups for hip arthroplasty

Background

Three-dimensional (3D) printing of porous titanium implants is increasing in orthopaedics, promising enhanced bony fixation whilst maintaining design similarities with conventionally manufactured components. Our study is one of the first to non-destructively characterize 3D-printed implants, using conventionally manufactured components as a reference.

Methods

We analysed 16 acetabular cups retrieved from patients, divided into two groups: ‘3D-printed’ (n = 6) and ‘conventional’ (n = 10). Coordinate-measuring machine (CMM), electron microscopy (SEM) and microcomputed tomography (micro-CT) were used to investigate the roundness of the internal cup surface, the morphology of the backside surface and the morphometric features of the porous structures of the cups, respectively. The amount of bony attachment was also evaluated.

Results

CMM analysis showed a median roundness of 19.45 and 14.52 μm for 3D-printed and conventional cups, respectively (p = 0.1114). SEM images revealed partially molten particles on the struts of 3D-printed implants; these are a by-product of the manufacturing technique, unlike the beads shown by conventional cups. As expected, porosity, pore size, strut thickness and thickness of the porous structure were significantly higher for 3D-printed components (p = 0.0002), with median values of 72.3%, 915 μm, 498 μm and 1.287 mm (p = 0.0002). The median values of bony attachment were 84.9% and 69.3% for 3D-printed and conventional cups, respectively (p = 0.2635).

Conclusion

3D-printed implants are designed to be significantly more porous than some conventional components, as shown in this study, whilst still exhibiting the same shape and size. We found differences in the surface morphologies of the groups, related to the different manufacturing methods; a key finding was the presence of partially molten particles on the 3D-printed cups.

Comparison of the Primary Stability of Porous Tantalum and Titanium Acetabular Revision Constructs

Adequate primary stability of the acetabular revision construct is necessary for long-term implant survival. The difference in primary stability between tantalum and titanium components is unclear. Six composite hemipelvises with an acetabular defect were implanted with a tantalum augment and cup, using cement fixation between cup and augment. Relative motion was measured at cup/bone, cup/augment and bone/augment interfaces at three load levels; the results were compared to the relative motion measured at the same interfaces of a titanium cup/augment construct of identical dimensions, also implanted into composite bone. The implants showed little relative motion at all load levels between the augment and cup. At the bone/augment and bone/cup interfaces the titanium implants showed less relative motion than tantalum at 30% load (p < 0.001), but more relative motion at 50% (p = n.s.) and 100% (p < 0001) load. The load did not have a significant effect at the augment/cup interface (p = 0.086); it did have a significant effect on relative motion of both implant materials at bone/cup and bone/augment interfaces (p < 0.001). All interfaces of both constructs displayed relative motion that should permit osseointegration. Tantalum, however, may provide a greater degree of primary stability at higher loads than titanium. The clinical implication is yet to be seen

Acetabular custom-made implants for severe acetabular bone defect in revision total hip arthroplasty: a systematic review of the literature

PURPOSE

The management of acetabular bone loss is a challenging problem in revision total hip arthroplasty (rTHA). The aim of this systematic review is to summarize and critically analyze indications, complications, clinical and radiological outcomes of custom-made acetabular components in rTHA.

METHODS

A systematic review of English literature was performed on Medline. Retrospective or prospective studies with minimum 2 years of follow-up (FU) were included. The PRISMA 2009 flowchart and checklist were considered to edit the review. Rates of intra- or post-operative complications, aseptic loosening (AL), periprosthetic joint infection (PJI), reoperations and re-revisions rates were extrapolated.

RESULTS

18 articles with a level of evidence of IV were included. Six hundred and thirty-four acetabular custom components (627 patients) with a mean FU of 58.6 ± 29.8 months were analyzed. The studies showed good clinical and functional outcomes. Custom-made acetabular components allowed a stable fixation with 94.0 ± 5.0% survival rate. The estimated rate of re-operations and re-revisions were 19.3 ± 17.3% and 5.2 ± 4.7%, respectively. The incidence of PJI was 4.0 ± 3.9%.

CONCLUSIONS

The acetabular custom-made implants represent a reliable solution for pelvic discontinuity and particular cases of bone loss classified as Paprosky Type IIIA-B or type III-IV according to American Academy of Orthopaedic Surgeons system where the feature of the defect cannot be handled with standard implants. This strategy allows to fit the implant to the residual host bone, bypassing the bony deficiency and restoring hip biomechanics. Satisfactory clinical and radiological outcomes at mid-term follow-up are reported in literature.

Mid-term results after revision total hip arthroplasty with custom-made acetabular implants in patients with Paprosky III acetabular bone loss

INTRODUCTION

Severe acetabular bone loss, both with or without pelvic discontinuity, remains a challenge in revision total hip arthroplasty (RTHA). The goal of our study was to evaluate the mid-term results for consecutive patients with Paprosky III acetabular bone loss with or without pelvic discontinuity who needed RTHA with custom-made acetabular implants and to compare the results to those of other studies.

MATERIALS AND METHODS

Sixty-eight (68) patients with severe acetabular bone loss (Paprosky Type IIIa and IIIb), who required RTHA, were included in our study. All prostheses were constructed on the basis of thin-layer computed tomography (CT) scans of the pelvis. The visual analogue scale (VAS), Harrison hip score (HHS), and clinical and radiographic follow-up assessments were used to evaluate the outcome.

RESULTS

The average follow-up time was 43 months (range 1-120 months). Implant survival at last follow-up was 75% (51 of 68). Kaplan-Meier survival analysis, with explantation as the endpoint, revealed survival rates of 82.7% (3 years) and 77% (5 years). Patients with revision of the acetabular component only had a significant higher survival rate (p 0.012). Overall revision rate was 36.7%. Reinfection rate was 34.4%. Complications included 15 (22%) periprosthetic joint infections (PJI), 7 dislocations (10.2%), and 2 aseptic loosenings (2.9%). Mean VAS at last follow-up was 1.45 compared to 3.2 preoperatively, while mean HHS improved from 21.1 points preoperatively to 61 at last follow-up. The change in both scores was thus significant (p < 0.001).

CONCLUSION

Defect reconstruction with custom-made modular acetabular implants can be a good, nevertheless expensive, treatment option with clinically and radiologically satisfying results in comparison to recent studies in the literature. Nevertheless, high postoperative complication rates, especially in terms of PJI, remain a challenge.

Evidence of structural cavities in 3D printed acetabular cups for total hip arthroplasty

The use of three-dimensional (3D) printing to manufacture off-the-shelf titanium acetabular cups for hip arthroplasty has increased; however, the impact of this manufacturing technology is yet not fully understood. Although several studies have described the presence of structural cavities in 3D printed parts, there has been no analysis of full postproduction acetabular components. The aim of this study was to investigate the effect of 3D printing on the material structure of acetabular implants, first comparing different designs of 3D printed cups, second comparing 3D printed with conventionally manufactured cups. Two of the 3D printed cups were produced using electron beam melting (EBM), one using laser rapid manufacturing (LRM). The investigation was performed using X-ray microcomputed tomography, imaging both the entire cups and samples sectioned from different regions of each cup. All 3D printed cups showed evidence of structural cavities; these were uniformly distributed in the volume of the samples and exhibited a prevalent spherical shape. The LRM-manufactured cup had significantly higher cavity density (p = .0286), with a median of 21 cavities/mm³ compared to 3.5 cavities/mm³ for EBM cups. However, the cavity size was similar, with a median of 20 μm (p = .7385). The conventional cups showed a complete absence of distinguishable cavities. The presence of cavities is a known limitation of the 3D printing technology; however, it is noteworthy that we found them in orthopedic implants used in patients. Although this may impact their mechanical properties, to date, 3D printed cups have not been reported to encounter such failures.

Comparative analysis of current 3D printed acetabular titanium implants

BACKGROUND

The design freedom allowed by three-dimensional (3D) printing enables the production of acetabular off-the-shelf cups with complex porous structures. The only studies on these designs are limited to clinical outcomes. Our aim was to analyse and compare the designs of different 3D printed cups from multiple manufacturers (Delta TT, Trident II Tritanium and Mpact 3D Metal).

METHODS

We analysed the outer surface of the cups using scanning electron microscopy (SEM) and assessed clinically relevant morphometric features of the lattice structures using micro-computed tomography (micro-CT). Dimensions related to the cup wall (solid, lattice and overall thickness) were also measured. Roundness and roughness of the internal cup surface were analysed with coordinate measuring machine (CMM) and optical profilometry.

RESULTS

SEM showed partially molten titanium beads on all cups, significantly smaller on Trident II (27 μm vs ~ 70 μm, p < 0.0001). We found a spread of pore sizes, with median values of 0.521, 0.841 and 1.004 mm for Trident II, Delta TT and Mpact, respectively. Trident II was also significantly less porous (63%, p < 0.0001) than the others (Delta TT 72.3%, Mpact 76.4%), and showed the thinnest lattice region of the cup wall (1.038 mm, p < 0.0001), while Mpact exhibited the thicker solid region (4.880 mm, p < 0.0044). Similar roundness and roughness of the internal cup surfaces were found.

CONCLUSION

This was the first study to compare the designs of different 3D printed cups. A variability in the morphology of the outer surface of the cups and lattice structures was found. The existence of titanium beads on 3D printed parts is a known by-product of the manufacturing process; however, their prevalence on acetabular cups used in patients is an interesting finding, since these beads may potentially be released in the body.

Porous Tantalum and Titanium in Orthopedics: A Review

Porous metal is metal with special porous structures, which can offer high biocompatibility and low Young's modulus to satisfy the need for orthopedic applications. Titanium and tantalum are the most widely used porous metals in orthopedics due to their excellent biomechanical properties and biocompatibility. Porous titanium and tantalum have been studied and applied for a long history until now. Here in this review, various manufacturing methods of titanium and tantalum porous metals are introduced. Application of these porous metals in different parts of the body are summarized, and strengths and weaknesses of these porous metal implants in clinical practice are discussed frankly for future improvement from the viewpoint of orthopedic surgeons. Then according to the requirements from clinics, progress in research for clinical use is illustrated in four aspects. Various creative designs of microporous and functionally gradient structure, surface modification, and functional compound systems of porous metal are exhibited as reference for future research. Finally, the directions of orthopedic porous metal development were proposed from the clinical view based on the rapid progress of additive manufacturing. Controllable design of both macroscopic anatomical bionic shape and microscopic functional bionic gradient porous metal, which could meet the rigorous mechanical demand of bone reconstruction, should be developed as the focus. The modification of a porous metal surface and construction of a functional porous metal compound system, empowering stronger cell proliferation and antimicrobial and antineoplastic property to the porous metal implant, also should be taken into consideration.

3D Printed Acetabular Cups for Total Hip Arthroplasty: A Review Article

Three-dimensional (3D) printed titanium orthopaedic implants have recently revolutionized the treatment of massive bone defects in the pelvis, and we are on the verge of a change from conventional to 3D printed manufacture for the mass production of millions of off-the-shelf (non-personalized) implants. The process of 3D printing has many adjustable variables, which taken together with the possible variation in designs that can be printed, has created even more possible variables in the final product that must be understood if we are to predict the performance and safety of 3D printed implants. We critically reviewed the clinical use of 3D printing in orthopaedics, focusing on cementless acetabular components used in total hip arthroplasty. We defined the clinical and engineering rationale of 3D printed acetabular cups, summarized the key variables involved in the manufacturing process that influence the properties of the final parts, together with the main limitations of this technology, and created a classification according to end-use application to help explain the controversial and topical issues. Whilst early clinical outcomes related to 3D printed cups have been promising, in-depth robust investigations are needed, partly because regulatory approval systems have not fully adapted to the change in technology. Analysis of both pristine and retrieved cups, together with long-term clinical outcomes, will help the transition to 3D printing to be managed safely.