Short to Midterm Follow-Up of the Tritanium Primary Acetabular Component: A Cause for Concern

Long-Term Outcomes and a Radiological Assessment of Hydroxyapatite-Tricalcium Phosphate-Coated Total Hip Arthroplasty (Trilogy/Zimmer): A Long-Term Follow-Up Study

Background and Objectives: Favorable short- and mid-term results for hydroxyapatite (HA)-tricalcium phosphate (TCP)-coated total hip arthroplasty (THA) (Trilogy/Zimmer) have been reported in the literature; however, the long-term results beyond 15 years have not been documented. Therefore, this study evaluated the long-term postoperative results, radiological bone changes, and implant fixation of the acetabular component of HA-TCP-coated THA. Materials and Methods: This is a retrospective cohort study of 212 patients who underwent primary HA-TCP-coated THA (Trilogy/Zimmer) at our institution between 1 October 2002, and 31 March 2008; 166 who were available for follow-up at least 15 years postoperatively were included (capture rate: 78.3%). All implants were Trilogy/Zimmer. We investigated the survival rate, with aseptic loosening as the endpoint. Clinical evaluations included the presence of dislocation and a modified Harris Hip Score (mHHS) preoperatively and at the final observation. Results: The mean age at surgery and at the follow-up period were 57.7 ± 9.6 and 17.1 ± 1.5 years, respectively. The survival rate was 99.4% (165/166), with aseptic loosening as the endpoint. Dislocation was observed in 4/166 (2.4%) patients. The mHHS improved significantly from 46.1 points preoperatively to 82.2 points during the last survey (p < 0.05). The results revealed that fixation was favorable in all cases except for one case of aseptic loosening. The Trilogy implant coated with HA-TCP was highly effective in bone induction, and bone ingrowth was considered to have occurred without failure, further indicating its usefulness. The long-term results of cementless THA using an HA-TCP coating (Trilogy/Zimmer), with a mean follow-up period of 17.1 years, revealed a commendable survival rate of 99.4%, considering aseptic loosening as the endpoint. Conclusions: HA-TCP-coated THA (Trilogy/Zimmer) had good long-term results. However, further long-term observation is required in patients who have undergone this surgery, and the stem side should be evaluated and investigated, including comorbidities.

Highly Porous Titanium Cups Frequently Presenting with Radiolucent Lines in Cementless Primary Total Hip Arthroplasty: A Retrospective Cohort Study

Background/Objectives: A highly porous titanium cup with a three-dimensional metal interface was recently introduced to improve biological fixation and survival. However, radiography has revealed concerns regarding these cups, despite their excellent short- and mid-term clinical outcomes. This study compared the clinical and radiographic results of a highly porous titanium cup with those of a hydroxyapatite-coated porous titanium cup after primary total hip arthroplasty (THA). Methods: Fifty-one primary THAs were investigated. A highly porous titanium cup was used in 17 hips, and a hydroxyapatite-coated porous titanium cup was used in 34 hips. No significant differences in preoperative patient demographic characteristics were observed between the two groups. The 2-year postoperative clinical and radiographic results were compared. Results: Radiolucent lines were observed in 13 (76%) of 17 hips with highly porous titanium cups and in none (0%) of 34 hips with hydroxyapatite-coated porous titanium cups (p < 0.001). In the highly porous titanium cup group, radiolucent lines were observed in five hips (29%) in one zone, two hips (11%) in two zones, and six hips (35%) in three zones. No cup loosening was observed in either group. Conclusions: Radiolucent lines were significantly more frequent in highly porous titanium cups. This study suggests that, compared to the three-dimensional structure of porous titanium, the hydroxyapatite coating of porous titanium had a greater influence on bone ingrowth in the short term. The meaning of these findings in the long-term is unclear yet.

A novel primary stability test method for artificial acetabular shells considering vertical load during level walking and shell position

Uncemented acetabular shell primary stability is essential for optimal clinical outcomes. Push-out testing, rotation testing, and lever-out testing are major evaluation methods of primary stability between the shell and bone. However, these test methods do not consider shell loads during daily activity and shell installation angle. This study proposes a novel evaluation method of acetabular shell primary stability considering load during level walking and acetabular installation angles such as inclination and anteversion. To achieve this, a novel primary stability test apparatus was designed with a shell position of 40° acetabular inclination and 20° anteversion. The vertical load, corresponding to walking load, was set to 3 kN according to ISO 14242-1, which is the wear test standard for artificial hip joints. The vertical load was applied by an air cylinder controlled by a pressure-type electro-pneumatic proportional valve, with the vertical load value monitored by a load cell. Torque was measured when angular displacement was applied in the direction of extension during the application of vertical load. For comparison, we also measured torque using the traditional lever-out test. The novel primary stability test yielded significantly higher primary stabilities; 5.4 times greater than the lever-out test results. The novel primary stability test failure mode was more similar to the clinical failure than the traditional lever-out test. It is suggested that this novel primary stability test method, applying physiological walking loads and extension motions to the acetabular shell, better reflects in vivo primary stability than the traditional lever-out test.

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.

Patient-reported and radiographic outcomes of a porous-coated acetabular cup in robotic assisted total hip arthroplasty at 2-year follow up

Introduction

Several implant manufacturers have developed ultra-porous metal substrate acetabular components recently. Despite this, data on clinical and radiographic outcomes remain limited. Our study evaluated postoperative patient-reported outcome measures (PROMs) and radiographic analyses in patients fitted with a novel acetabular porous-coated component.

Methods

A total of 152 consecutive patients underwent a total hip arthroplasty by a single orthopaedic surgeon. All patients underwent surgery utilizing the same CT-scan based robotic-assisted device with the same porous cementless acetabular shell. They received standardized postoperative physical therapy, rehabilitation, and pain protocols. Preoperatively, first postoperative visit, 6-months, 1-year, and 2-years, patients were evaluated based on Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain, physical function, and total scores; 2) Patient-Reported Outcomes Measurement Information System (PROMIS)-10 physical and mental scores; 3) Hip Disability and Osteoarthritis Outcome Score (HOOS)-Jr scores; as well as 4) acetabular component positions and 5) evidence of acetabular component loosening.

Results

Significant improvements were observed by 6 months in WOMAC pain, physical function, and total scores (p < 0.05), maintained at 1 and 2 years. PROMIS-10 physical scores also improved significantly from preoperative to 6 months postoperative and remained so at 1 and 2 years postoperative (p < 0.05). No significant changes were found in PROMIS-10 mental scores. HOOS-Jr scores significantly improved from preoperative to 6 months postoperative and remained so through 2 years (p < 0.05). At 6 months, slight changes were noted in abduction angle and horizontal and vertical offset. Radiolucencies, initially found in 3 shells, reduced to 1 shell with 2 new radiolucencies by 6 months, and remained stable with no subsequent operative interventions. At 1 year and 2 years, no radiographic abnormalities were noted, including complete resolution of prior radiolucencies as well as stable components.

Conclusion

This porous cementless acetabular shell, implanted with CT-scan-based robotic-assisted techniques, demonstrated excellent postoperative PROMs at 2 years. Stable radiolucencies suggest good component stability. The early stable clinical and radiographic results suggest promising long-term outcomes with this device.

Level of evidence

III (retrospective cohort study).

Comparative Survival of Contemporary Cementless Acetabular Components Following Revision Total Hip Arthroplasty

BACKGROUND

The advent of highly porous ingrowth surfaces and highly crosslinked polyethylene has been expected to improve implant survivorship in revision total hip arthroplasty. Therefore, we sought to evaluate the survival of several contemporary acetabular designs following revision total hip arthroplasty.

METHODS

Acetabular revisions performed from 2000 to 2019 were identified from our institutional total joint registry. We studied 3,348 revision hips, implanted with 1 of 7 cementless acetabular designs. These were paired with highly crosslinked polyethylene or dual-mobility liners. A historical series of 258 Harris-Galante-1 components, paired with conventional polyethylene, was used as reference. Survivorship analyses were performed. For the 2,976 hips with minimum 2-year follow-up, the median follow-up was 8 years (range, 2 to 35 years).

RESULTS

Contemporary components with adequate follow-up had survivorship free of acetabular rerevision of ≥95% at 10-year follow-up. Relative to Harris-Galante-1 components, 10-year survivorship free of all-cause acetabular cup rerevision was significantly higher in Zimmer Trabecular Metarevision (hazard ratio (HR) 0.3, 95% confidence interval (CI) 0.2-0.45), Zimmer Trabecular MetaModular (HR 0.34, 95% CI 0.13-0.89), Zimmer Trilogy (HR 0.4, 95% CI 0.24-0.69), DePuy Pinnacle Porocoat (HR 0.24, 95% CI 0.11-0.51), and Stryker Tritanium revision (HR 0.46, 95% CI 0.24-0.91) shells. Among contemporary components, there were only 23 rerevisions for acetabular aseptic loosening and no rerevisions for polyethylene wear.

CONCLUSION

Contemporary acetabular ingrowth and bearing surfaces were associated with no rerevisions for wear and aseptic loosening was uncommon, particularly with highly porous designs. Therefore, it appears that contemporary revision acetabular components have dramatically improved upon historical results at available follow-up.

Middle-term outcome and complications after primary total hip arthroplasty using a contemporary titanium tapered wedge cementless femoral stem

The purpose of this study is to evaluate the results and intraoperative or postoperative complications of primary total hip arthroplasty (THA) using a contemporary tapered wedge titanium femoral component. A total of 213 THAs in 187 patients were followed up more than 5 years (mean, 102 months ; range, 60-150). The mean age at surgery was 64.2 years (range, 20?89 years). These patients were clinically evaluated using the JOA scoring system and radiographically host bone reactions around the implants, as well as femoral loosening. The mean JOA score improved from 49 (range, 21?75) to 92 (range, 59?100). All 12 patients with poor results (JOA < 75) coexisted with cerebral, spinal, joint, and musculoskeletal disorders. At the final follow-up, implant survival was 100%. Complications occurred in 23 hips. They consisted of 12 hips with intra-operative fractures, 2 hips with sciatic nerve palsy, one hip with infections, 3 hips with recurrent dislocations, and 8 hips with aseptic cup loosening. In conclusion, we have shown excellent survival rate of the contemporary tapered wedge stem in primary THA ; however, patients with coexisting diseases could not acquire sufficient improvement in hip function and ambulatory ability. J. Med. Invest. 70 : 471-475, August, 2023.

Primary Tritanium acetabular components have increased rates of radiolucency associated with inferior clinical outcomes at short-term follow-up

INTRODUCTION

Cementless fixation is the standard for acetabular fixation in primary total hip arthroplasty (THA). There are various surface finishes thought to improve osteointegration, although literature regarding the long-term survival of some of these surfaces is limited. Regardless of design, primary stability is essential to allow for osteointegration. Previous studies have suggested an increased rate of radiolucency and compromised short-term functional outcomes using the Tritanium primary acetabular component (Stryker, Mahwah, NJ). The purpose of this study was to compare the primary Tritanium acetabular component to another contemporary acetabular component as a control group with an established clinical record.

METHODS

444 consecutive, primary THAs performed by a single surgeon from 2008 to 2012 were reviewed. Patients were included if they had a minimum 1-year follow-up. Implant survivorship and modified Harris Hip Scores (mHHS) were recorded for all patients at final follow-up. Radiographs were evaluated by 2 surgeons at 6 weeks, 1 year, and the most recent follow-up for evidence of radiolucency and migration. Components were considered to have evidence of radiographic lucency if they had radiolucency in 2 or more DeLee zones.

RESULTS

198 patients met criteria for inclusion (96 Pinnacle, 102 Tritanium). Average follow-up was 28 (12-72) months. At final follow-up 6.2% of the Pinnacle cups and 29.4% of the Tritanium cups had radiographic evidence of loosening (p < 0.01). The average mHHS for the Tritanium group was 83.1, and 88.4 for the Pinnacle group (p < 0.01). Radiographic evidence of loosening also correlated with a lower mHHS: 75.5 versus 86.4 (p < 0.01). In patients that received Tritanium cups without screw fixation 44.6% showed radiographic evidence of loosening versus 8% that received screw fixation (p < 0.01). In total, 6 patients in the Tritanium group required revision for aseptic loosening of the acetabular component.

CONCLUSIONS

The 30% rate of radiographic loosening in the Tritanium group was significantly higher than the Pinnacle group and correlated with an inferior clinical outcome. Interestingly the use of screw augmentation was protective against radiographic evidence of loosening. This suggests that the Tritanium component may be prone to fibrous in-growth because of inadequate primary stability.

Failure of Screw/Shell Interface in the Trident II Acetabular System in Total Hip Arthroplasty

We report a case series of 2 patients with screw/shell interface failure in the Stryker Trident II Acetabular System. Both failures consisted of screw penetration through the Trident II acetabular shell. One failure was observed postoperatively after a revision from a cephalomedullary nail to a total hip arthroplasty while the other was observed intraoperatively during a primary total hip arthroplasty. Both component failures were managed conservatively with weight-bearing as tolerated and radiographic monitoring. These are the first reported cup/screw failures of the Stryker Trident II system and should raise awareness of the potential complication and implant design flaw. When placing acetabular screws, we recommend obtaining intraoperative orthogonal screw radiographs that are tangential to the shell surface to assess for screw/shell failure.

Efficacy and Safety of Acetabular Cup without Screw Fixation in Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Background and Objectives: Adequate initial fixation of the uncemented acetabular component in total hip arthroplasty is necessary to achieve long-term survival. Although screw fixation contributes to improved cup stability, there is currently no consensus on the use of this method. This study aimed to assess the existing randomized controlled trials (RCTs) on the efficacy and safety of cup fixation in total hip arthroplasty without screws. Materials and Methods: We searched the EMBASE, MEDLINE, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov databases to identify RCTs published before February 2022. Primary outcomes were reoperation, cup migration, and Harris Hip Score. Secondary outcomes were the presence of a radiolucent line in the acetabular region, translation and rotation movement, and polyethylene wear. We conducted meta-analyses using the random-effects models. The revised Cochrane risk-of-bias tool was used to assess the risk of bias for outcomes of interest; the Grading of Recommendations, Assessment, Development, and Evaluation approach was used to summarize the body of evidence. Results: We included six reports from four studies. Total hip arthroplasty without screw fixation to the acetabular cup had little to no effect on reoperation (pooled relative risk, 0.98; 95% confidence interval, 0.14-6.68; I2 = 0%), cup migration (pooled relative risk, 1.72; 95% confidence interval, 0.29-10.33; I2 = 1%), Harris Hip Score (mean difference, 1.19; 95% confidence interval, -1.31-3.70; I2 = 0%), radiolucent line (pooled relative risk, 5.91; 95% confidence interval, 0.32-109.35), translation and rotation of all axes, and polyethylene wear (mean difference, 0.01; 95% confidence interval, -0.01-0.04; I2 = 0%), with very low certainty of evidence on all measures. Conclusions: The efficacy of acetabular cups without screw fixation in total hip arthroplasty remains uncertain, suggesting the need for prudent clinical application. Further large-scale, well-designed studies with low risk of bias are required.

Revision for Aseptic Loosening of Highly Porous Acetabular Components in Primary Total Hip Arthroplasty: An Analysis of 20,993 Total Hip Replacements

BACKGROUND

Highly porous-coated titanium acetabular components have a high coefficient of friction and ultraporous surfaces to enhance bone ingrowth and osseointegration in total hip arthroplasty (THA). There have been concerns with the development of early radiolucent lines and aseptic loosening of highly porous acetabular components. It is unclear whether these concerns relate to a specific implant or the entire class. The aim of this study is to compare the revision rates for aseptic loosening of highly porous acetabular combinations in primary THA using data from a large joint replacement registry.

METHODS

Data were retrieved from the Australian Orthopedic Association National Joint Replacement Registry for the study period September 1999 to December 2019. All primary THA procedures recorded and performed for osteoarthritis using the most common combinations for each highly porous acetabular component with highly cross-linked polyethylene and a 32-mm or 36-mm femoral head were included. The primary outcome measure was revision for aseptic loosening of the acetabular component. Results were adjusted for patient age and gender.

RESULTS

There were 20,993 primary THA procedures performed for osteoarthritis using a highly porous acetabular component across 6 combinations. Relative to the POLARSTEM/R3 (StikTite), the Exeter V40/Tritanium had a significantly higher risk of revision for aseptic loosening of the acetabular component (hazard ratio 0.21, 95% confidence interval 0.06-0.74, P = .014). There was no difference between any other highly porous acetabular component combination and no late revisions for aseptic loosening.

CONCLUSION

Highly porous-coated titanium acetabular components have low rates of aseptic loosening with long-term follow-up. A difference between components may exist.

LEVEL OF EVIDENCE

Level III.

The Diagnosis and Treatment of Acetabular Bone Loss in Revision Hip Arthroplasty: An International Consensus Symposium

Despite growing evidence supporting the evaluation, classification, and treatment of acetabular bone loss in revision hip replacement, advancements have not been systematically incorporated into a single document, and therefore, a comprehensive review of the treatment of severe acetabular bone loss is needed. The Stavros Niarchos Foundation Complex Joint Reconstruction Center at Hospital for Special Surgery held an Acetabular Bone Loss Symposium on June 21, 2019, to answer the following questions: What are the trends, emerging technologies, and areas of future research related to the evaluation and management of acetabular bone loss in revision hip replacement? What constitutes the optimal workup and management strategies for acetabular bone loss? The 36 international experts convened were divided into groups, each assigned to discuss 1 of 4 topics: (1) preoperative planning and postoperative assessment; (2) implant selection, management of osteolysis, and management of massive bone loss; (3) the treatment challenges of pelvic discontinuity, periprosthetic joint infection, instability, and poor bone biology; and (4) the principles of reconstruction and classification of acetabular bone loss. Each group came to consensus, when possible, based on an extensive literature review. This document provides an overview of these 4 areas, the consensus each group arrived at, and directions for future research.

Radiographic assessment of the dynasty biofoam acetabular component with a minimum 2 years follow-up

INTRODUCTION

Acetabular components utilising novel ultraporous metal matrices have been recently introduced into clinical practice with improved interference fit, decreased stress shielding, and hope for more reliable osseointegration. 1 such example is the Dynasty Biofoam cup, which has been in clinical use for over a decade but has few reports documenting its clinical and radiographic performance.

METHODS

A single-centre retrospective study was performed evaluating 96 Dynasty Biofoam acetabular components implanted between March 2010 and August 2014 with minimum 2-year radiographic follow-up. Patients that received components for revision surgery or that had early complications postoperatively (femur fracture, prosthetic infection) were excluded. Biofoam patients were compared to 96 patients that received the Trident PSL acetabular component and were matched for age, gender, and BMI. Patient reported outcomes, component position and radiographic features of cup loosening, including radiolucent lines and sclerosis were compared among groups.

RESULTS

Patient-reported outcomes at 2 years were similar among groups. Cup anteversion was similar but inclination was significantly greater in the Biofoam group (p = 0.006). A significantly greater number of Biofoam components exhibited 2-zone (27.2%) and 3-zone (12.0%) radiolucencies compared to 0% of the Trident shells (p < 0.05). 2 Biofoam cups were revised for aseptic loosening compared to no Trident cups (p = 0.49).

DISCUSSION

Despite adequate implant survivorship, over a quarter of Biofoam cups had 2 or more radiolucent zones in early follow-up. Longer follow-up is needed to determine if the aseptic revision rate for this cup will increase.

Clinical and radiological outcomes of total hip arthroplasty using a highly porous titanium cup or a conventional hydroxyapatite-coated titanium cup: A retrospective study in Japanese patients

BACKGROUND

A highly porous titanium cup has a unique structure that mimics human trabecular bone and is expected to achieve better outcomes due to rigid fixation and extensive bone ingrowth. Several manufacturers have developed a highly porous titanium cup; however, some have shown a high incidence of radiolucent lines (RLLs) on early postoperative radiographs. In this study, we compared the clinical and radiological outcomes of total hip arthroplasty (THA) using a highly porous titanium cup (OsseoTi, Zimmer Biomet) with those after THA using a conventional hydroxyapatite-coated titanium cup (Trident HA, Stryker).

METHODS

A total of 201 hips that underwent THA using an OsseoTi cup (n = 101) or Trident cup (n = 100) were enrolled in the study. Patient characteristics, cup alignment, clinical outcome (determined by the Japanese Orthopedic Association [JOA] score), and incidence of RLLs around the cup were evaluated at 3, 6, 12, and 24 months postoperatively.

RESULTS

The clinical outcome was excellent in both groups. The incidence of RLLs was 12.9% at 3 months, 20.8% at 6 months, 23.8% at 12 months, and 22.8% at 24 months after surgery in the OsseoTi group; there were no cases of RLL at any time after surgery in the Trident group. The RLLs were mainly distributed in zone 2. Despite the high rate of RLL in the OsseoTi group, the RLL were narrow and only 5% had a width of >1 mm at 24 months postoperatively. There were no cases with RLLs in all three zones.

CONCLUSIONS

Despite excellent clinical outcomes in both study groups, the incidence of RLLs was higher in the OsseoTi group than in the Trident group. Although none of our cases with RLL have required revision surgery for aseptic loosening so far, these patients require careful follow-up.

Outcomes Following Revision for Mechanically Assisted Crevice Corrosion in a Single Femoral Design

BACKGROUND

Mechanically assisted crevice corrosion (MACC) is a described complication following metal-on-polyethylene (MoP) total hip arthroplasty (THA). The literature regarding outcomes following revision for MACC suggests that complication rates are high. The purpose of this investigation is to add to this literature with the largest reported series to date.

METHODS

This is a retrospective cohort study of 552 consecutive patients who underwent 621 MoP primary THAs. We identified patients who subsequently underwent revision THA for a diagnosis of MACC. All patients were implanted with the same implant combination (Accolade I stem/cobalt-chromium low friction ion treatment femoral head). Patient demographic, surgical, and laboratory data were collected. Follow-up was calculated from the revision surgery and Hip Disability and Osteoarthritis Outcome Score Joint Replacement and hip subjective values (HSV) were examined at final follow-up. Descriptive statistics were performed.

RESULTS

The revision rate for MACC was 11.6% and mean time to revision was 6.6 (±2.4) years. Revised patients (n = 69) had a mean preoperative serum cobalt-chromium ratio of 3.5 (±2.4). There were 8 cases of gross trunnion failure. At mean 3.2 (±1.9) years following revision, the overall major complication rate was 11.6% with a 5.8% reoperation rate. At final follow-up, mean Hip Disability and Osteoarthritis Outcome Score Joint Replacement scores were 83.2 (±15.6) and mean hip subjective value was 77.6 (±17.4). Revision resulted in significant increases in both parameters (P < .001).

CONCLUSION

The incidence of MACC in MoP THA is likely higher than previously reported, particularly for certain implant combinations. Revision surgery for MACC can achieve good outcomes but a high clinical suspicion with early detection and revision is likely key to success.

Do trabecular metal cups achieve better results when compared to hemispherical porous titanium cups in acetabular revision surgery?

BACKGROUND

Trabecular metal (TM) cups were introduced in order to achieve better ingrowth and stability of the cup in acetabular revision surgery. As their use has evolved over time, we have queried whether TM cups would improve results in terms of the rate of aseptic loosening when compared to historical uncemented porous titanium cups used in revision surgery for acetabular bone loss in Hospital La Paz (Madrid, Spain).

METHODS

We retrospectively reviewed 197 acetabular revisions performed between 1991 and 2015. Titanium cups were used in 81 cases and TM cups in 116. The mean follow-up was 8.1 years (range 1-15); 12.0 ± 7.8 for titanium group and 5.4 ± 3.1 for TM group. The most common reason for revision was aseptic loosening. A Kaplan-Meier analysis was used to determine the survival of the cup, with radiological failure and re-revision due to aseptic loosening as the endpoints. Cox multivariate regression analyses were performed to assess different risk factors for failure.

RESULTS

1 TM cup and 1 titanium cup were re-revised due to aseptic loosening (p = 0.61). Radiological cup loosening was observed in 4 TM cups and 2 titanium cups (p = 1.0). At 6 years, the probability of not having radiological cup loosening was 97.4% (95% CI, 93.9-100) for the titanium cups and 95.1% for the TM cups (95% CI, 90.1-99.9) (p = 0.59). Another 5 cups were re-revised due to dislocation. Hips with a greater Paprosky defect showed a higher risk of loosening (p < 0.05, hazard risk (HR) 3.04; 95% CI, 0.97-9.54).

CONCLUSIONS

This study shows there was no significant difference in re-revision due to aseptic loosening or radiological loosening between titanium and TM cups in revision surgery for acetabular bone loss. Both types of cups demonstrate excellent results with a low failure rate and minimal complications.

Long-Term Outcomes of a Titanium-Encased Ceramic Liner Total Hip Arthroplasty (15 to 21Year Results)

BACKGROUND

Historically, aseptic loosening and osteolysis were responsible for most of the revisions among young and more active patients. Ceramic-on-ceramic bearings reduced wear but presented mechanical issues such ceramic fracture or liner chipping during insertion. To prevent this from happening a titanium-encased alumina liner was developed. The aim of this study is to address long-term results of this specific ceramic design.

METHODS

All patients received an uncemented acetabular component with ceramic-on-ceramic bearing (94 hips in 77 patients). Patients were prospectively followed over 15 years. Clinical evaluation included the Harris Hip Score and Visual Analog Scale pain scale. Radiographic analysis included integration, osteolysis, and ceramic-related mechanical issues, such as malseating of the insert.

RESULTS

The studied acetabular design survivorship was 98.9% at a mean follow-up of 17.2 years. One arthroplasty was revised secondary to infection but no cup had loosened or migrated during the study. Only 1 cup showed complete radiolucent lines. There was no fracture of any ceramic component in the study group. Malseating was present in 12 acetabular components (12.8%). No osteolysis was observed with over 15 years of follow-up.

CONCLUSION

In conclusion, this acetabular component demonstrates a favorable clinical and radiological outcome with over 15 years of follow-up. Osteolysis was not observed and incomplete seating of the titanium-sleeved ceramic liner did not lead to mechanical problems.

Excellent mid-term outcomes with a hemispheric titanium porous-coated acetabular component for total hip arthroplasty: 7-10 year follow-up

INTRODUCTION

Third-generation hemispheric, titanium porous-coated (HTPC) acetabular cups have been shown to achieve good biologic fixation through enhanced porous ingrowth surfaces. They also allow for a wide range of bearing options, including polyethylene, dual-mobility, and ceramic liners. The purpose of the study is to review the mid-term clinical outcomes an HTPC acetabular cup with a minimum of 7-year follow-up.

METHODS

A retrospective, observational study was conducted on all consecutive patients who underwent total hip arthroplasty (THA) with an HTCP acetabular cup at an urban, tertiary referral centre. Descriptive statistics were used describe baseline patient characteristics. Outcomes collected included postoperative complications, survival free of reoperations, and presence of osteolysis at latest imaging follow-up. Implant survival was analysed using the Kaplan-Meier method.

RESULTS

118 cases (114 primary, 4 revision) underwent THA with the HTCP acetabular cup at an average follow-up of 8.16 ± 0.85 years (range 7.02-10.28 years). Mean patient age at the time of surgery was 61.29 ± 12.04 years. All cases utilised a high-molecular-weight polyethylene (HMWPE) liner. None of the acetabular cups showed loosening or migration at the latest follow-up. There were 2 revisions in our study, 1 for abductor mechanism disruption and 1 due to surgical site infection where the acetabular cup was revised. Kaplan-Meier survivorship analysis for all-cause revision at 7 and 10-year follow-up showed a survival rate of 99.1% (95% confidence interval, 94.1-99.9%). Survivorship analysis for aseptic acetabular revision at 10-year follow-up showed a survival rate of 100%.

CONCLUSIONS

At long-term follow-up, no radiologic and minimal clinical complications were identified in this series. The HTPC acetabular cup system, used in conjunction with a HMWPE liner, demonstrates excellent outcomes and survivorship when compared to earlier mid-term studies published in the literature.

Is there a problem with modular dual mobility acetabular components in revision total hip arthroplasty at mid-term follow-up?

AIMS

Modular dual mobility (MDM) acetabular components are often used with the aim of reducing the risk of dislocation in revision total hip arthroplasty (THA). There is, however, little information in the literature about its use in this context. The aim of this study, therefore, was to evaluate the outcomes in a cohort of patients in whom MDM components were used at revision THA, with a mean follow-up of more than five years.

METHODS

Using the database of a single academic centre, 126 revision THAs in 117 patients using a single design of an MDM acetabular component were retrospectively reviewed. A total of 94 revision THAs in 88 patients with a mean follow-up of 5.5 years were included in the study. Survivorship was analyzed with the endpoints of dislocation, reoperation for dislocation, acetabular revision for aseptic loosening, and acetabular revision for any reason. The secondary endpoints were surgical complications and the radiological outcome.

RESULTS

The overall rate of dislocation was 11%, with a six-year survival of 91%. Reoperation for dislocation was performed in seven patients (7%), with a six-year survival of 94%. The dislocations were early (at a mean of 33 days) in six patients, and late (at a mean of 4.3 years) in four patients. There were three intraprosthetic dissociations. An outer head diameter of ≥ 48 mm was associated with a lower risk of dislocation (p = 0.013). Lumbrosacral fusion was associated with increased dislocation (p = 0.004). Four revision THAs (4%) were further revised for aseptic acetabular loosening, and severe bone loss (Paprosky III) at the time of the initial revision was significantly associated with further revision for aseptic acetabular loosening (p = 0.008). Fourteen acetabular components (15%) were re-revised for infection, and a pre-revision diagnosis of reimplantation after periprosthetic joint infection (PJI) was associated with subsequent PJI (p < 0.001). Two THAs had visible metallic changes on the backside of the cobalt chromium liner.

CONCLUSION

When using this MDM component in revision THA, at a mean follow-up of 5.5 years, there was a higher rate of dislocation (11%) than previously reported. The size of the outer bearing was related to the risk of dislocation. There was a low rate of aseptic acetabular loosening. Longer follow-up of this MDM component and evaluation of other designs are warranted. Cite this article: Bone Joint J 2021;103-B(7 Supple B):66-72.

Adoption of Robotic Arm-Assisted Total Hip Arthroplasty Results in Reliable Clinical and Radiographic Outcomes at Minimum Two-Year Follow Up

INTRODUCTION

Longevity and success of total hip arthroplasty (THA) is largely dependent on component positioning. While use of robotic platforms can improve this positioning, published evidence on its clinical benefits is limited. Therefore, the aim of this study was to assess the clinical outcomes of THA with robotic surgical assistance.

MATERIALS AND METHODS

We conducted an analysis of robotic arm-assisted primary THAs performed by a single surgeon utilizing a posterior approach. A total of 99 patients (107 cases) who had a minimum two-year follow up were identified. Their mean age was 61 years (range, 33 to 84 years), and their mean body mass index was 30.5 kg/m2 (range, 18.5 to 49.1 kg/m2). There were 56% female patients and primary osteoarthritis was the principal hip diagnosis in 88.8%. Operative times, lengths of hospital stay, and discharge dispositions were recorded, along with any complications. Modified Harris Hip Scores (HHS) were calculated to quantify clinical outcomes.

RESULTS

Mean postoperative increases in HHS at 2- to 5.7-year follow up was 33 points (range, 6 to 77 points). There were no complications attributable to the use of robotic assistance. Surgical-site complications were rare; one case underwent a revision for prosthetic joint infection (0.93%) but there were no dislocations, periprosthetic fractures, or cases of mechanical implant loosening. There was no evidence of progressive radiolucencies or radiographic failure.

DISCUSSION

Robotic arm-assisted THA resulted in low complication rates at minimum two-year follow up, with clinical outcomes comparable to those reported with manual surgery.1-4 The haptically-guided acetabular bone preparation enabled reliable cementless acetabular fixation and there were no adverse events related to the use of the robot. Dislocations were avoided in this case series. Randomized controlled clinical trials are needed to compare manual to robotic surgery and to investigate whether the precision found with this functional planning will reliably reduce the incidence of dislocations.

Radiographic assessment of radiolucent lines around a highly porous titanium cup (Tritanium) using digital tomosynthesis, after total hip arthroplasty

BACKGROUND

The objectives of this study were to assess radiolucent lines around a highly porous titanium cup (Tritanium) using digital tomosynthesis and to investigate the clinical and radiographic factors associated with radiolucent lines on tomosynthesis.

METHODS

Fifty-five patients underwent total hip arthroplasty using a Tritanium cup, and digital tomosynthesis and plain radiography were performed at 1 week, 6 months, 1 year, and 2 years after surgery. The radiolucent lines around the cup were measured on both DTS and plain radiography at each postoperative period. Clinical evaluations were performed by the Japanese Orthopaedic Association hip disease evaluation questionnaire (JHEQ), and revision surgeries were examined. Based on the presence of radiolucent lines on digital tomosynthesis at 2 years postoperatively, patients were divided into RL (+) and RL (-) groups and investigated for related factors.

RESULTS

There were 20 cases in the RL (+) group and 35 cases in the RL (-) group, and no revision surgeries were required. Statistically, there were more cases with radiolucent lines on digital tomosynthesis (45.4% at 1 week and 36.3% at 2 years) than on plain radiography (9.1% at 1 week and 9.1% at 2 years) at each postoperative point. Logistic analysis showed no significant associations between the presence of radiolucent lines at 2 years on digital tomosynthesis, and the JHEQ parameters of pain (p = 0.937), movement (p = 0.266), or mental status (p = 0.404).

CONCLUSION

In a short-term evaluation up to 2 years, digital tomosynthesis detected more radiolucent lines around the titanium cups than plain radiography. The occurrence of radiolucent lines was not related to the postoperative clinical evaluation.

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.

Minimum 7-year Follow-up of A Porous Coated Trabecular Titanium Cup Manufactured with Electron Beam Melting Technique in Primary Total Hip Arthroplasty

OBJECTIVES

To investigate the cup survivorship, patient satisfaction level, clinical function, and radiographic outcomes of patients who underwent total hip arthroplasty (THA) using electron beam melting (EBM)-produced porous coated titanium cups at mid-term follow up.

METHODS

A total of 32 patients (32 hips) from five hospitals in China who underwent primary THA using EBM-produced trabecular titanium cups between May and December 2012 were retrospectively reviewed. The inclusion criteria were: (i) patients who underwent THA with the use of EBM-produced cups with possible 7-year follow up; and (ii) patients with follow-up information, including the cup survivorship, patient satisfaction level, and clinical outcomes such as Harris hip score. The exclusion criteria were: (i) patients with neuropathic diseases; and (ii) patients who underwent THA due to neoplastic disease. Five (15.6%) patients were lost to follow up before the 7-year follow-up and, thus, were excluded; none of these patients died due to disease associated with the THA or had undergone removal of their cups as of our last evaluation. The mean age and body mass index of the patients were 59.37 (range: 38.00-69.00) years and 24.51 (range: 16.50-34.10) kg/m² , respectively. Thirteen (48.1%) of the patients were female.

RESULTS

The average duration of follow-up was 93.48 (range: 89.00-99.00) months. The median Harris hip score improved from 42.00 (interquartile range: 37.00-49.00) to 97.00 (interquartile range: 92.00-97.00) at the latest follow up (P < 0.001). A total of 18 (66.7%) patients rated their satisfaction level as very satisfied, 6 (22.2%) as satisfied, 2 (7.4%) as neutral and 1 (3.7%) as dissatisfied. No intraoperative or postoperative complications were identified. At the latest follow up, all cups were considered to have achieved osteointegration fixation, with three or more of the five signs evident in the most recent X-ray. However, three cups revealed radiolucent lines with a width of less than 1 mm. The median vertical and horizontal distances between the latest postoperative center of rotation relative to the anatomic center of rotation were 2.50 (interquartile range: -3.10, 6.94) mm superiorly and 3.26 (interquartile range: -8.12, 2.38) mm medially, respectively, at the most recent postoperative follow up. Kaplan-Meier survivorship analysis of cups, with the endpoint defined as postoperative radiolucent lines of less than 1 mm in width in at least two zones, reveals that the 8.25-year survival was 96.3% (95% confidence interval: 76.49%-99.47%).

CONCLUSION

The mid-term follow-up of patients who underwent primary THA using EBM-produced porous coated titanium cups demonstrated favorable patient satisfaction, good clinical function, excellent survivorship, and adequate biological fixation.

The Fate of Zone 2 Radiolucencies in Contemporary Highly Porous Acetabular Components: Not All Designs Perform Equally

Background

The enhanced frictional resistance of modern ultraporous acetabular components can impede complete seating; however, surgeons expect the enhanced ingrowth surface to resolve polar (zone 2) gaps over time via osseointegration. This study characterized zone 2 radiographic osseointegration in 3 acetabular component designs: 2 highly porous ingrowth and one traditional ongrowth.

Methods

A consecutive cohort of primary total hip arthroplasties was reviewed which utilized 3 different acetabular cup designs: ongrowth titanium with hydroxyapatite (HA), highly porous titanium with machined radial grooves (MRG), and dual-porous titanium substrate with micropore (MP). Radiographic analysis was performed using accepted measurement criteria with particular attention to radiolucent lines.

Results

Seven hundred ninety cases were available for analysis. Initial 1-month radiographs revealed 43.2% of HA, 78.2% of MRG, and 81.0% of MP cups exhibited zone 2 radiolucencies, consistent with incomplete seating. At 1 year, all HA radiolucencies resolved, whereas 46.2% and 34.7% of radiolucencies remained in MRG and MP cups, respectively (P ≤ .005). At minimum 2 years, a significant proportion of zone 2 radiolucencies remained in 46.0% of MRG compared with 23.9% of MP cups and 3.0% of HA cups (P ≤ .007).

Conclusion

The resolution of zone 2 radiolucencies at 1-year and minimum 2-year follow-up signified osseointegration for nearly all HA and most MP cups. Highly porous titanium cups with machined radial grooves demonstrated persistent zone 2 radiolucencies at 1 year and beyond. Given reports of early loosening with this particular acetabular implant, further follow-up is warranted as this study highlights that not all contemporary highly porous metal acetabular components perform equally.

Level of Evidence

III.

Impact of Acetabular Implant Design on Aseptic Failure in Total Hip Arthroplasty

Background

Failure of cementless acetabular osseointegration is rare in total hip arthroplasty. Nevertheless, new fixation surfaces continue to be introduced. Novel implants may lack large diameter, constrained bearings, or dual mobility (DM) bearings to address instability. We compared clinical and radiographic outcomes for acetabular components with differing fixation surfaces and bearing options, focusing on the relationship between fixation surface and osseointegration and the relationship between bearing options and dislocation rate.

Methods

We retrospectively reviewed 463 total hip arthroplasties implanted with 3 different acetabular components between 2012 and 2016. Records were reviewed for demographics, clinical scores, and complications. Radiographs were examined for evidence of acetabular osteointegration. Analysis of variance and chi-square tests were used to compare cohorts.

Results

All cohorts had 100% survivorship free of acetabular fixation failure with no differences in clinical scores. Dislocation occurred in 1.3% of cases (n = 6). Analysis of the “transition” sizes, for which brand determined the maximum bearing diameter, revealed a significantly higher dislocation rate (3/50, 6%) in implants with limited bearing options. All 4 revisions for recurrent dislocation involved well-positioned components that did not accept large diameter, constrained bearings, or DM bearings, resulting in 3 shell revisions to expand bearing options. Femoral revisions were associated with dislocation risk but did not vary between cohorts.

Conclusion

Dislocation was the primary mechanical cause for acetabular revision, while acetabular fixation failure was not encountered. We caution against selecting “new and improved” acetabular components without options for large diameter, constrained bearings, or DM bearings, even when enabling technology makes component positioning reliable.

Implant Survival of 6,080 Tritanium Cups in Primary Total Hip Arthroplasty: Data from the Finnish Arthroplasty Register from 2009 to 2017

BACKGROUND

To enhance osseointegration in total hip arthroplasty (THA), ultraporous or highly porous-coated cups were introduced. Implant survival data on these new devices have been scarce. The aim of our study was to assess the survivorship of ultraporous Tritanium cups (Stryker) in a population-based register study.

METHODS

In this study, we collected data on 6,080 primary THAs using a Tritanium cup and 25,670 THAs using a conventional cup (control group) from the Finnish Arthroplasty Register; these procedures were performed from January 1, 2009, to December 31, 2017. We calculated the Kaplan-Meier survival estimates with 95% confidence intervals (CIs). The end point was revision for any reason or for aseptic loosening of the cup. The revision risks were assessed with use of the Cox multiple regression model. The variables assessed in the Cox model were femoral head size, age group, involved side, operation year, sex, diagnosis, and fixation of the stem. The proportional hazards assumption of the Cox model was not fulfilled, so the follow-up time was divided into 3 time periods: 0 to 2 years, >2 to 4 years, and >4 years.

RESULTS

When comparing the 2 groups with regard to revision for any reason, the 5-year Kaplan-Meier survivorship of the Tritanium group (94.7% [95% CI, 94.0% to 95.4%]) was inferior to that of the control group (96.0% [95% CI, 95.7% to 96.3%]). In the Cox regression analysis of the 2 groups for the time period of >4 years, the Tritanium group had an increased risk of revision for any reason compared with the control group (hazard ratio [HR], 3.12 [95% CI, 1.82 to 5.35]; p < 0.001). With regard to revision for aseptic loosening of the cup, the Tritanium group had an increased risk of revision compared with the control group for both 0 to 2 years (HR, 3.80 [95% CI, 1.76 to 8.24]; p < 0.001) and >2 to 4 years (HR, 11.2 [95% CI, 3.28 to 38.0]; p < 0.001).

CONCLUSIONS

There was no advantage to using the ultraporous-coated Tritanium cup for primary THA compared with conventional uncemented cups. However, wide CIs for some HR estimates may point to a lack of precision. Therefore, further research on subject is needed.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

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.

Inferior extended fixation utilizing porous titanium augments improves primary anti-rotational stability of the acetabular component

BACKGROUND

The primary anti-rotational stability is critical to preventing cup tilting failure following revision total hip arthroplasty, but is frequently compromised by severe ischial bone loss. A novel technique of "inferior extended fixation" was introduced by securing a porous metal augment into the deficient ischium. This study evaluated the effect of this technique on primary anti-rotational stability in revision total hip arthroplasty.

METHODS

Composite hemipelvis specimens, acetabular components and "lotus" augments were used to simulate total hip arthroplasty surgeries. Three different cementless operative settings of cup implantation were simulated: (1) native ischium without defects; (2) ischium with a defect not reconstructed; (3) ischial defect reconstructed with inferior extended fixation using a lotus augment. Lever-out testing was used to examine primary anti-rotational stability, which was measured as interface stiffness and yield moment.

FINDINGS

Compared with the native ischium setting, the mean interface stiffness decreased by 53.1% in the ischial defect setting (p < 0.001). In the inferior extended fixation setting, the mean value was 110% greater than that in the ischial defect setting (p = 0.014), and comparable to that in the native ischium setting (p = 1). Similar results were observed for the yield moment (declined by 63.1%, p < 0.001; 200% higher, p < 0.001; and p = 0.395; respectively).

INTERPRETATION

In revision total hip arthroplasty with severe ischial defects, inferior extended fixation with a lotus porous titanium augment restores anti-rotational stability of the acetabular component to the level of that with a native ischium, which provides the mechanical environment for bone ingrowth and prevents cup tilting failure.

Partial Bone Formation in Additive Manufactured Porous Implants Reduces Predicted Stress and Danger of Fatigue Failure

New porous implant designs made possible by additive manufacturing allow for increased osseointegration, potentially improving implant performance and longevity for patients that require massive bone implants. The aim of this study was to evaluate how implantation and the strain distribution in the implant affect the pattern of bone ingrowth and how changes in tissue density within the pores alter the stresses in implants. The hypothesis was that porous metal implants are susceptible to fatigue failure, and that this reduces as osteointegration occurs. A phenomenological, finite element analysis (FEA) bone remodelling model was used to predict partial bone formation for two porous (pore sizes of 700 μm and 1500 μm), laser sintered Ti₆Al₄V implants in an ovine condylar defect model, and was compared and verified against in vivo, histology results. The FEA models predicted partial bone formation within the porous implants, but over-estimated the amount of bone-surface area compared to histology results. The stress and strain in the implant and adjacent tissues were assessed before, during bone remodelling, and at equilibrium. Results showed that partial bone formation improves the stress distribution locally by reducing stress concentrations for both pore sizes, by at least 20%. This improves the long-term fatigue resistance for the larger pore implant, as excessively high stress is reduced to safer levels (86% of fatigue strength) as bone forms. The stress distribution only changed slightly in regions without bone growth. As the extent of bone formation into extensively porous bone implants depends on the level of stress shielding, the design of the implant and stiffness have significant influence on bone integration and need to be considered carefully to ensure the safety of implants with substantial porous regions. To our knowledge this is the first time that the effect of bone formation on stress distribution within a porous implant has been described and characterised.

Highly Porous Titanium Cups versus Hydroxyapatite-Coated Sockets: Midterm Results in Metachronous Bilateral Total Hip Arthroplasty

OBJECTIVE

Highly porous titanium cups have been recently introduced, with contradictory outcomes. A retrospective consecutive case series involving bilateral metachronous total hip arthroplasties (THA) performed with 2 different cups, i.e., Fixa (F) and Fixa Ti-Por (T) (Adler Ortho, Milan, Italy), and the same stem, was evaluated. T sockets, manufactured using electron beam melting, were supposed to prove superior in terms of clinical results, survival rates, and radiographic parameters in comparison to hydroxyapatite-coated F cups with conventional porosity.

SUBJECTS AND METHODS

Twenty-four bilateral metachronous THAs with an F cup on one side and a T socket on the other side were evaluated. Preoperative and postoperative Harris hip scores (HHS) were collected for every patient. Radiographic signs of loosening were assessed. The radiographic signs of osseointegration (radiolucent lines, superolateral buttress, inferomedial buttress, radial trabeculae, and stress shielding) were evaluated.

RESULTS

No intraoperative complications occurred. The mean HHS score was excellent and comparable in both groups. At the mean follow-up of 134 months (F) and 79 months (T), no cup or liner revisions were performed. No radiographic signs of loosening were reported. All of the patients revealed 3 parameters of good bony ingrowth at least. Both groups showed similar radiographic parameters regarding osseointegration, which were stable over the time. Stress shielding was more evident in the T cohort (p =0.07).

CONCLUSION

Highly porous titanium cups produced using an additive manufacturing and electron beam melting technology achieved reliable midterm clinical and radiographic results not inferior to those of second-generation cups.

Radiolucency around highly porous sockets and hydroxyapatite-coated porous sockets in total hip arthroplasty for hip dysplasia

Studies over the past decade have reported that the use of highly porous sockets in total hip arthroplasty (THA) results in osseointegration and long-term implant stability. However, some reports have raised concerns regarding radiographic evidence of poor osseointegration with features of fibrous tissue ingrowth. The purpose of this study was to compare clinical and radiographic assessments of highly porous sockets with those of hydroxyapatite (HA)-coated porous sockets in THA for hip dysplasia (DDH) at least 1 year after surgery. A total of 127 patients (136 hips) were recruited for the study. Of these, 94 patients (101 hips) received highly porous sockets with clustered screws, while 33 patients (35 hips) received HA-coated porous sockets with clustered screws. There was no difference in clinical outcomes between the two types of sockets. All HA-coated porous sockets were radiographically stable, without radiolucent lines. Fifteen hips had radiolucent lines in two or three DeLee and Charnley zones, accompanied by sclerotic lines along the circumferences of the highly porous sockets. A significant difference in the height of the preoperative osteophyte of the anterior acetabular wall was observed between 86 hips with one or no radiolucent lines and 15 hips with two or three radiolucent lines. In cases of DDH with atrophic bone remodeling pattern, highly porous sockets with multiple screws may be used, while HA-coated porous sockets with clustered screws result in better sealing of the bone–component interface.

Comparison of a highly porous titanium cup (Tritanium) and a conventional hydroxyapatite-coated porous titanium cup: A retrospective analysis of clinical and radiological outcomes in hip arthroplasty among Japanese patients

BACKGROUND

The use of 3-dimensional highly porous acetabular cups is increasing. Their structure and mechanical properties mimic those of natural bone; therefore, they should promote stronger biological fixation. In our experience with total hip arthroplasty, radiolucent lines are observed when a 3-dimensional highly porous cup (Stryker Tritanium) is used. We compared the clinical and radiographic results between a Tritanium cup and a conventional cup (Stryker Trident HA) over a short time period.

METHOD

We retrospectively compared consecutive cases of primary total hip arthroplasty using a Tritanium cup (130 cases in 118 patients) and a matched cohort using a Trident cap (130 cases in 130 patients) between January 2011 and December 2014.

RESULTS

The mean follow-up duration was 41.3 and 38.1 months (p = 0.06) for the Tritanium and Trident groups, respectively. There were significant differences between the groups for radiolucent lines, cup abduction angle, and cup-center-edge angle. There were no significant differences in the clinical results. Radiolucent lines increased in the Tritanium group (36.1% at 3 months and 60.7% at final follow-up), whereas they decreased in the Trident group (2.5% at 3 months and 0.8% at final follow-up). The occurrence of radiolucent lines was significantly higher in the Tritanium group than in the Trident group at each follow-up period. Radiolucent lines were seen in 36.1% of patients in the Tritanium group during follow-up, without initial gaps. One cup loosening in the Tritanium group was identified at the final follow-up evaluation.

CONCLUSION

Both groups showed successful clinical results over short-term follow-up; however, the Tritanium group had a significantly higher rate of radiolucent line occurrence around the cups than did the Trident group. Thus, radiolucent lines can occur when using highly porous titanium cups; these lines indicate the possibility of future cup loosening. Longer follow-up and assessment of the results of using this implant are necessary.

Radiographic and Clinical Outcomes of Porous Titanium-Coated and Plasma-Sprayed Acetabular Shells: A Five-Year Prospective Multicenter Study

BACKGROUND

New materials in cementless total hip arthroplasty are continuously introduced into clinical practice. The objective of this study was to compare the radiographic and clinical performances of acetabular shells made with porous titanium coating (PTC) and plasma-sprayed titanium (PS).

METHODS

Data from a prospective multicenter study monitoring PTC and PS shells were analyzed. Three hundred and eighty patients (191 with PTC and 189 with PS) with postoperative (within 10 months after the operation) and 5-year radiographs were available for assessment of radiographic outcomes and patient-reported outcome measures (PROMs). A radiolucent distance between the cup and acetabulum of ≥0.5 mm was defined as a gap if it was found on a postoperative radiograph and as a radiolucency if it was found on a later follow-up radiograph for the first time.

RESULTS

Postoperative gaps were more common with the PS shell (40% versus 24%, p < 0.001). However, a higher percentage of the gaps in the PTC group persisted at 5 years (56% versus 4%, p < 0.001). At 5 years, 23% of the PTC shells had a radiolucency versus 5% of the PS shells (p < 0.001). Logistic regression revealed a 5.2-fold increase in the odds for radiolucency with the PTC shell (p < 0.001). No patient underwent revision surgery due to acetabular component loosening within the study period. A PTC shell was the only factor associated with the risk of pain in a logistic regression model (odds ratio = 2.0, p = 0.035).

CONCLUSIONS

PTC shells were associated with more patient-reported pain and a higher risk of radiolucency and a persistent gap at 5 years compared with the PS shells, although these outcomes were not related to each other. The clinical relevance of the radiographic findings is unclear as no prostheses were revised because of loosening, but the findings warrant additional follow-up studies.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Cementless Total Knee Arthroplasty: A Comprehensive Review of the Literature

This review evaluated (1) original and newer cementless implants; (2) outcomes of newer designs; (3) risks and benefits; and (4) newer cementless vs cemented total knee arthroplasties. A search for all reports on cementless total knee arthroplasties published from January 2010 to April 2017 was performed, and 31 studies were included for final analysis. Newer cementless total knee arthroplasty designs have shown excellent survivorship, functional outcomes, and satisfaction rates in both young and elderly populations. Compared with cement fixation, there may be potential benefits with the newer cementless implants. However, these findings need to be further substantiated with additional studies reporting longer-term results. [Orthopedics. 2018; 41(5):263-273.].

Tritanium Acetabular Cup in Revision Hip Replacement: A Six to Ten Years of Follow-Up Study

BACKGROUND

The use of highly porous acetabular components has shown to produce good results in revision acetabular surgery. Their surface characteristics enhance initial fixation and bone ingrowth which are prerequisites for adequate osseointegration. The purpose of this study is to analyze the mid-term to long-term survival, clinical and radiological outcomes using the Tritanium cup (Stryker, Mahwah, NJ) in revision hip surgery.

METHODS

This is a retrospective review of all patients who underwent acetabular revision surgery using "Tritanium revision cup" between April 2007 and November 2010 at our institution. Sixty-two patients were included with a mean age of 67.5 years (32-86). According to Paprosky classification, 10 patients had type I defect, 8 had type IIA, 27 had type IIB, 7 had type IIC, and 10 suffered from type IIIA defect. A Kaplan-Meier analysis was used to determine the survival of the cup. Functional outcomes were assessed using Oxford Hip Score. Plain radiographs were performed to assess implant fixation and osseointegration.

RESULTS

The acetabular cup aseptic survivorship was 98.4% at a mean follow-up of 87.6 months. The mean Oxford Hip Score improved from 14.5 (3-31) preoperatively to 38.5 (12-48) at the final follow-up. Two cups were revised (3.2%): 1 for aseptic loosening and 1 for infection.

CONCLUSION

Tritanium revision acetabular cup has shown excellent mid-term to long-term clinical and radiographic results with low failure rate and minimal complications. Longer term follow-up would be of value to assess the ongoing survival of this implant construct.

Early aseptic loosening of the Tritanium primary acetabular component with screw fixation

Ultraporous acetabular components were developed to improve osseointegration and fit for increased longevity and better outcomes after total hip arthroplasty. There is a paucity of literature detailing this acetabular component's clinical performance, with even less detailing those with screw fixation. We identify 5 patients at our institution who underwent revision total hip arthroplasty for early aseptic acetabular cup loosening of an ultraporous acetabular component known as the Tritanium primary cup with secondary screw fixation. They all presented with groin and hip pain after index surgery and underwent follow-up radiographic examination consistent with component loosening requiring revision surgery. This case series reports on the risk of early acetabular cup loosening and its associated clinical presentation, workup, and surgical management in patients with the Tritanium primary cup augmented with screws.

Comparison of the Primary Stability of a Porous Coated Acetabular Revision Cup With a Standard Cup

BACKGROUND

The number of revision hip arthroplasty procedures has been increasing substantially, with the acetabular component requiring component revision in over half of the cases. New porous implant designs attempt to improve outcomes due to improved osseointegration; however, sufficient primary stability is paramount for good osseointegration.

METHODS

We compared 2 revision cups of the same geometry, yet different surface properties in an in vitro scenario: a porous titanium surface and a conventional sintered-bead titanium surface. These were tested in 10 cadaveric pelvises under a physiologic cyclic partial weight-bearing scenario. Each side was randomly implanted with one of the implants. Relative motion between the bone and cup was measured using an optical measuring device. Statistical evaluation was carried out descriptively using a covariance analysis with repeated measures and a test of fixed effects, with significance determined as P < .05.

RESULTS

The conventional cup displayed an average relative motion of 28.02 μm; and the porous implant displayed an average relative motion of 33.42 μm. There was no statistically significant difference between the two with regard to the resultant relative motion (P = .2649). The bone mineral density does have a significant influence on resultant relative motion (P = .0406), with higher bone mineral density correlating with less relative motion in both implants.

CONCLUSION

The porous implant provides similar primary stability to the conventional implant in the tested scenario; the motion of both implants relative to the bone was within safe limits for osseointegration. Bone stock must be considered when choosing implant type and postoperative care.

Three-Year Outcomes of a Highly Porous Acetabular Shell in Primary Total Hip Arthroplasty

This multicenter study evaluated survivorship, functional outcomes, complications, and radiographic outcomes for patients who underwent total hip arthroplasty using a newly developed highly porous 3-dimensional titanium implant. Excellent aseptic (99.6%) and all-cause (98%) survivorship and functional outcomes were found at 3-year follow-up. This highly porous acetabular shell holds promise in total hip arthroplasty. [Orthopedics. 2018; 41(1):e154-e157.].