Migration of the trabecular metal monoblock acetabular cup system

Does a Monoblock Acetabular Component With a Ceramic Liner Cause More Pelvic Bone Loss Than a Conventional Modular Cementless Acetabular Component? A 2-Year Randomized Clinical Trial

BACKGROUND

Ceramic-on-ceramic bearings permit the use of large femoral head size while maintaining a favorable effect on wear rates. However, because of increased device rigidity, periprosthetic bone quality could be negatively affected due to stress shielding. The purpose of this study is to assess pelvic periprosthetic bone remodeling around a monoblock ceramic-on-ceramic acetabular component compared to that around a conventional modular metal-on-polyethylene device.

METHODS

Participants were randomized to receive hip replacement using either a porous-coated, modular metal-on-polyethylene acetabular component (n = 46) or a hydroxyapatite and titanium-coated monoblock shell with an integrated ceramic-on-ceramic bearing (n = 40). Radiographic assessments were completed preoperatively and postoperatively, and measurements of bone mineral density (BMD) using dual-energy X-ray absorptiometry with region free analysis were performed postoperatively and over 2-years of follow-up.

RESULTS

There was no significant difference in BMD between the 2 groups at baseline or over the following 2 years. At follow-up, complete shell-to-bone contact without a radiolucent line was observed in 26 (67%) of the modular devices and in 37 (93%) of monoblock (P < .001). The modular device was an independent predictor of radiolucent lines (odds ratio 19.1, P = .007). No cases underwent revision surgery for acetabular loosening.

CONCLUSION

Both the porous-coated modular and hydroxyapatite-coated monoblock acetabular components showed successful clinical results at short-term follow-up with no difference in pixel-level BMD. Using a large head monoblock device does not appear to be associated with an adverse effect on the local bone environment when compared to a modular device. NCT: NCT01558752.

The concept of a cementless isoelastic monoblock cup made of highly cross-linked polyethylene infused with vitamin E: radiological analyses of migration and wear using EBRA and clinical outcomes at mid-term follow-up

Background

The newest generation of cementless titanium-coated, isoelastic monoblock cup with vitamin E-blended highly cross-linked polyethylene (HXLPE) was introduced to the market in 2009. The aim of the present study was to obtain mid-term follow-up data including migration and wear analyses.

Methods

This prospective study investigated 101 primary total hip arthroplasty (THA) cases in 96 patients treated at a single institution. Patients were allowed full weight-bearing on the first day postoperatively. Harris hip score (HHS) and pain and satisfication on a visual analogue scale (VAS) were assessed at a mean follow-up of 79.0 months. Migration and wear were assessed using Einzel-Bild-Roentgen-Analyse (EBRA) software. Radiological acetabular bone alterations and complications were documented.

Results

At mid-term follow-up (mean 79.0 months, range: 51.8–101.7), 81 cases with complete clinical and radiological data were analyzed. Utilisable EBRA measurements were obtained for 42 hips. The mean HHS was 91.1 (range 38.0–100.0), VAS satisfaction was 9.6 (range 6.0–10.0), VAS rest pain was 0.2 (range 0.0–4.0), and VAS load pain was 0.6 (range 0.0–9.0). Mean migration was 0.86 mm (range: 0.0–2.56) at 24 months and 1.34 mm (range: 0.09–3.14) at 5 years, and the mean annual migration rate was 0.22 (range: − 0.24–1.34). The mean total wear was 0.4 mm (range: 0.03–1.0), corresponding to a mean annual wear rate of 0.06 mm per year (range: 0.0–0.17). Radiographic analysis did not reveal any cases of osteolysis, and no revision surgeries had to be performed.

Conclusions

After using vitamin-E blended HXLPE in cementless isoelastic monoblock cups, there were no obvious signs of osteolysis or aseptic loosening occurred. No patients required revision surgery after mid-term follow-up. Cup migration and wear values were well below the benchmarks considered predictive for potential future failure.

Trial registration

The trial registration number on ClinicalTrials.gov: NCT04322916 (retrospectively registered at 26.03.2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-03981-8.

Trabecular Metal Acetabular Components Reduce the Risk of Revision Following Primary Total Hip Arthroplasty: A Propensity Score Matched Study From the National Joint Registry for England and Wales

BACKGROUND

Trabecular metal (TM)-coated acetabular components are increasingly used in both primary and revision total hip arthroplasty (THA). However, previous studies assessing TM acetabular components have been small single-center cohorts with most lacking a control group. We compared revision rates following primary THA between TM and non-TM-coated acetabular components.

METHODS

A retrospective observational study was performed using National Joint Registry data, which included primary THAs with the same cementless acetabular component (either TM or non-TM coated). TM and non-TM implants were matched for multiple potential confounding factors using propensity scores. Outcomes following primary THA (revision for all-cause acetabular indications, aseptic acetabular loosening, and infection) were compared between matched groups using competing risk regression analysis.

RESULTS

In 18,200 primary THAs (9100 TM and 9100 non-TM), the overall prevalence of acetabular revision, revision for aseptic acetabular loosening, and septic revision was 1.2%, 0.13%, and 0.59% respectively. Five-year revision rates for all-causes (1.0% vs 1.8%, sub-hazard ratio [SHR] 0.57, 95% confidence interval [CI] 0.43-0.76, P < .001), aseptic acetabular loosening (0.1% vs 0.2%, SHR 0.35, 95% CI 0.14-0.90, P = .029), and infection (0.5% vs 0.9%, SHR 0.51, 95% CI 0.34-0.76, P = .001) were all lower in TM compared with non-TM implants.

CONCLUSION

Following primary THA, TM-coated acetabular implants had a reduced risk of both aseptic and septic revision compared with non-TM implants. Although absolute differences in revision risk were small, they may be clinically significant if TM designs were implanted in more complex cases.

Survivorship of a Porous Tantalum Monoblock Acetabular Component in Primary Hip Arthroplasty With a Mean Follow-Up of 18 Years

BACKGROUND

The use of porous tantalum for the acetabular component in primary total hip arthroplasty (THA) has demonstrated excellent short-term and midterm results. However, long-term data are scarce. The purpose of this prospective study is to report the long-term clinical and radiologic outcome following use of an uncemented porous tantalum acetabular component in primary THA with a minimum follow-up of 17.5 years, in a previously studied cohort of patients.

METHODS

We prospectively followed 128 consecutive primary THAs in 140 patients, between November 1997 and June 1999. A press-fit porous tantalum monoblock acetabular component was used in all cases. All patients were followed clinically and radiographically for a mean of 18.1 years (range, 17.5-19 years).

RESULTS

Mean age of patients at the time of operation was 60.4 years. Harris hip score, Oxford hip score, and range of motion were dramatically improved in all cases (P < .001). At last follow-up, all cups were radiographically stable with no evidence of migration, gross polyethylene wear, progressive radiolucencies, osteolytic lesions, or acetabular fractures. The survivorship with reoperation for any reason as end point was 92.8% and the survivorship for aseptic loosening as an end point was 100%.

CONCLUSION

The porous tantalum monoblock cup in primary THA demonstrated excellent clinical and radiographic outcomes with no failures because of aseptic loosening at a mean follow-up of 18.1 years.

Shell design and reaming technique affect deformation in mobile-bearing total hip arthroplasty acetabular components

Press-fit acetabular components are susceptible to rim deformation. The inherent variability within acetabular reaming techniques may generate increased press-fit and, subsequently, additional component deformation. The purpose of this study was to analyze the insertion and deformation characteristics of acetabular components designed for dual-mobility systems based on component design, size, and reaming technique. Shell deformation was quantified in a validated worst-case scenario foam pinch model. Thin-walled, one-piece, and modular dual-mobility shells of varying size were implanted in under- and over-reamed cavities with insertion force measured and shell deformation assessed using digital image correlation. Increased shell size resulted in larger rim deformation in one-piece components, with a reduction in press-fit by 1 mm resulting in up to 48% reduction in insertion forces and between 23% and 51% reduction in shell deformation. Lower insertion forces and deformations were observed in modular components. Variability in acetabular reaming plays a significant role in the ease of implantation and component deformation in total hip arthroplasty. Modular components are less susceptible to deformation than thin-walled monoblock shells. Care should be taken to avoid excessive under-reaming, particularly in the scenario of large shell size and high-density patient bone stock.

Does a titanium-coated polyethylene press-fit cup give reliable midterm results?

BACKGROUND

Uncemented acetabular components have demonstrated low revision rates and high patient satisfaction but with concerns regarding increased costs compared with monoblock cups. Some newer lower-cost uncemented monoblock options have become available in the last decade, but limited data are available on their performance.

QUESTIONS/PURPOSES

(1) Does an uncemented, titanium-backed all-polyethylene acetabular cup provide reliable fixation? (2) What is the frequency and what are the causes for revision with this cup?

METHODS

Between 2004 and 2008, we elected to use an uncemented, titanium-backed all-polyethylene acetabular cup in older patients with limited physical demands. We performed 615 hip replacements in 550 patients with greater than 5 years of clinical and radiographic followup. When patients who were dead (80 hips in 75 patients), lost to followup (98 hips in 93 patients), or revised (three hips in three patients) were excluded, there were 434 hips in 379 patients for comparison of the postoperative and 5-year radiographs. Two observers not involved in the index surgical procedures (NH, HS) assessed radiographs for signs of migration or loosening. Some degree of early movement sometimes is seen before cup stabilization; however, to be conservative, we defined cups with greater than 3° of change of position (even if they subsequently stabilized) as potentially at risk and report them separately. Revision surgery, time from the index procedure, and the reason for revision were recorded from the New Zealand Joint Registry.

RESULTS

By 5 years there was a median change in inclination of 2° (range, 0°-13°; 95% confidence interval [CI], 2.0-2.4; p < 0.001) and 2° of anteversion (range, 0°-11°; 95% CI, 2.0-2.4; p < 0.001). Although at last followup all cups appeared to have stabilized with no radiolucent lines or medial migration, 22% of the cups (94 of 434) had moved more than 3° and so were deemed to be potentially at risk. There were 11 revision procedures (of 429 hips; 2.5%) of which six were for recurrent dislocation, four for femoral fracture, and one for femoral loosening to give an overall all-cause revision rate for all components of 0.25 per 100 component years (95% CI, 0.13-0.43). No revisions were performed for acetabular loosening.

CONCLUSIONS

The short- to medium-term results of this all-polyethylene monoblock cup demonstrated a low frequency of revision. However, 94 cups were identified as potentially at risk based on movement of > 3° before apparent stabilization. Although those patients seem to be doing well enough now, the current duration of followup may not be sufficient to know that these cups will be durable, because other ongrowth designs have demonstrated a high frequency of late failure after apparent early success.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Performance of Porous Tantalum vs. Titanium Cup in Total Hip Arthroplasty: Randomized Trial with Minimum 10-Year Follow-Up

Porous tantalum monoblock cups have been proposed to improve survivorship of cementless primary THA. However, there are few direct comparative trials to established implants such as porous-coated titanium cups. 113 patients were randomized into two groups according to the cup: a porous tantalum monoblock cup (TM) or a porous-coated titanium monoblock cup (control). At a mean of 12 years after THA, no implants migrated in both groups. Two TM patients (4%) and 13 control patients (33%) presented with radiolucency around the cup (P<0.001). In the control group, 1 cup (2%) was revised for aseptic loosening. At 12 years post-implantation, porous tantalum monoblock cups demonstrated 100% survivorship, and significantly less radiolucency as compared to porous-coated titanium monoblock cups.

An uncemented iso-elastic monoblock acetabular component: preliminary results

Little is known about the clinical application of highly cross-linked polyethylene (HXLPE) blended with vitamin E. This study evaluates an uncemented iso-elastic monoblock cup with vitamin E blended HXLPE. 112 patients were followed up for 2years. 95.5% completed the follow-up. The mean VAS score for patient satisfaction was 8.8 and the mean Harris Hip Score was 94.2. In 7 cases initial gaps behind the cup were observed, which disappeared completely during follow-up in 6 cases. The mean femoral head penetration rate was 0.055mm/year. No adverse reactions or abnormal mechanical behavior was observed with the short term use of vitamin E blended HXLPE. This study shows the promising performance of this cup and confirms the potential of vitamin E blended HXLPE.

Five-year results of the uncemented RM pressfit cup clinical evaluation and migration measurements by EBRA

This was a prospective consecutive, study of 50 patients (mean age 72 years, 56% males) treated unilaterally for primary osteoarthrosis using the uncemented, isoelastic, monoblock RM Pressfit Cup. Migration and wear were assessed using the EBRA (Ein-Bild-Röntgen-Analyse) software (201 radiographs from 36 patients). Mean migration was 0.82 mm after 2 years and 1.25 mm after 5 years. A decreasing migration rate over the period was observed. The mean annual wear rate was 0.09 mm/y. Five years after surgery, 84% of patients reached good or excellent Harris hip score values. No revisions related to the acetabular component were necessary. All cups appeared to have high primary stability.

Excellent results of primary THA using a highly porous titanium cup

Cementless acetabular cups for primary total hip arthroplasty have had excellent results, with failure rates typically less than 5% at up to 10-year follow-up. Tritanium is a 3-dimensional metal interface that has been used for porous biological fixation. The purpose of this study was to review the clinical and radiographic results of the use of Tritanium cups (Stryker Orthopaedics, Mahwah, New Jersey) for primary total hip arthroplasty. Two hundred eighty-eight total hip arthroplasties performed using a porous titanium acetabular cup in 252 patients between 2008 and 2010 were reviewed. One hundred thirty-three men and 119 women with a mean age of 58 years (range, 18-88 years) were included. Mean follow-up was 36 months (range, 24-56 months). Outcomes evaluated were implant survivorship, Harris Hip Score, complications, and radiographic outcomes. At final follow-up, no cup failures had occurred. Mean Harris Hip Score improved from 53 points (range, 33-82 points) preoperatively to 91 points (range, 64-100 points) postoperatively. One complication occurred; a 64-year-old woman with recurrent postoperative effusions underwent hip exploration and required abductor mechanism repair. On radiologic evaluation, no signs existed of progressive radiolucencies or changes in cup position. The survivorship of the Tritanium cup and the low complication rate is comparable with previous studies using other porous-metal prostheses. Longer follow-up study is needed and assessment of the results of using this implant in the revision setting is important.

Smoking may be a harbinger of early failure with ultraporous metal acetabular reconstruction

BACKGROUND

Smoking is considered a risk factor for surgical complications in total hip arthroplasty (THA) and has been linked to a higher rate of aseptic loosening in uncemented acetabular components. Acetabular reconstruction with newer ultraporous metals in both complex primary and revision THA has increased survivorship but it is unclear whether smoking affects survival of these implants.

QUESTIONS/PURPOSES

We reviewed our early experience with THA using ultraporous acetabular components to assess the incidence and etiology of early failure and examine if any preoperative variables, including smoking, related to failure.

METHODS

We used ultraporous acetabular components in 498 patients (534 hips), beginning with one case each in 1999 and 2004, 17 in 2005, and the majority from 2006 through March 2010. There were 159 complex primary and 375 revision cases. Of these patients, 17% were smokers (averaging 35 pack-years), 31% previous smokers (averaging 29 pack-years), 41% nonsmokers, and 1% unknown. Failure modes possibly related to smoking were infection, aseptic loosening, or periacetabular fracture and unrelated were dislocation and implant breakage. Minimum followup was 1 month (average, 32 months; range, 1-78 months).

RESULTS

There were 34 cup failures (6%): 17 infections, 14 aseptic loosening, and one each liner breakage, dislocation, and periacetabular fracture. The failure rate (uncontrolled for potentially confounding variables) was 10% in both current (9 of 89) and prior smokers (17 of 167) and 3% in nonsmokers 8 of 271).

CONCLUSION

With ultraporous metal technology in complex primary and revision THA, smoking, both past and current, may be a risk factor for early failure.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Osseous integration in porous tantalum implants

Porous tantalum is a biomaterial that was recently introduced in orthopedics in order to overcome problems related to implant loosening. It is found to have osteoconductive, and possibly, osteoinductive properties hence useful in difficult cases with severe bone defects. So, it is of great interest to shed light on the mechanisms through which this material leads to new bone formation, after being implanted. Porous tantalum is biologically relatively inert, with restricted bonding capacity to the bone is restricted. In order to overcome this obstacle, it undergoes thermal processing in an alkaline environment. This process leads to extensive hydroxyapatite formation on its surface, and thus, to better integration of porous tantalum implants. Apart from this, new bone tissue formation occurs inside the pores of the porous tantalum after its implantation and this new bone retains the characteristics of the normal bone, that is, bone remodeling and Haversian systems formation. This finding is enhanced by the observation that porous tantalum is an appropriate substrate for osteoblast adherence, proliferation, and differentiation. Furthermore, the finding that osteoblasts derived from old women (> 60 years old) and cultivated on porous tantalum may grow faster than osteoblasts taken from younger women (< 45 years old) and cultivated on other substrates, can partially explain porous tantalum's good performance in cases of patients with severe bone defects. In conclusion, porous tantalum's chemical and mechanical properties are those that probably define the already noticed good performance of this material. However, further research is needed to totally clarify the mechanisms.

Comparison of trabecular metal cups and titanium fiber-mesh cups in primary hip arthroplasty: a randomized RSA and bone mineral densitometry study of 50 hips

BACKGROUND

Trabecular metal has shown promising results in experimental studies of bone ingrowth. Several clinical studies support these results. However, until now, no randomized clinical radiostereometric analysis (RSA) studies have been published. In this randomized RSA trial, we compared a new acetabular cup with a surface made of tantalum trabecular metal and a cup with a titanium fiber-mesh surface.

PATIENTS AND METHODS

Between 2004 and 2006, we operated 60 patients with noninflammatory hip arthritis. The patients were randomized to receive either an uncemented cup with a titanium fiber-mesh surface (Trilogy cup) or a cup with a trabecular tantalum surface (Monoblock cup). After 2 years, 50 patients had completed the study. The primary endpoint was cup migration within the first 2 years after surgery; the secondary endpoints were change in bone mineral density and Harris hip score at 3 months.

RESULTS

Both cup types showed excellent fixation. RSA revealed minimal translation and rotation at 2 years. There was no statistically significant difference between the cup types with regard to translation. However, less rotation along the transverse axis was seen in the trabecular metal cups than in the fiber mesh cups: mean -0.01º (95% CI: -0.11 to 0.12) for trabecular metal cups and -0.60º (-0.72 to -0.48) for fiber-mesh cups (p = 0.04). The degree of periprosthetic bone loss was similar between the cup types in any of the regions of interest at 2 years of follow-up. 3 months postoperatively, we found a similar increase in Harris hip score in both groups: from around 50 to over 90.

INTERPRETATION

We found promising early results concerning fixation of trabecular metal components to the acetabular host bone. However, we recommend a longer observation period to evaluate the outcome of this new cup design.

The Trabecular Metal Monoblock acetabular component in patients with high congenital hip dislocation: a prospective study

Between November 1997 and December 2000 we performed 27 total hip replacements in 22 patients with high congenital dislocation of the hip using porous tantalum monoblock acetabular components implanted in the true acetabular bed. Clinical and radiological evaluation was performed at regular intervals for a mean of 10.2 years (8.5 to 12). The mean Harris Hip Score improved from 48.3 (15 to 65) pre-operatively to 89.5 (56 to 100) at the final follow-up. The mean Oxford Hip Score was 49.5 (35 to 59) pre-operatively and decreased to 21.2 (12 to 48) at one year and 15.2 (10 to 28) at final follow-up. Migration of the acetabular component was assessed with the EBRA software system. There was a mean migration of 0.68 mm (0.49 to 0.8) in the first year and a mean 0.89 mm (0.6 to 0.98) in the second year, after excluding one initial excessive migration. No revision was necessary for any reason, no acetabular component became loose, and no radiolucent lines were observed at the final follow-up. The porous tantalum monoblock acetabular component is an implant offering adequate initial stability in conjunction with a modulus of elasticity and porosity close to that of cancellous bone. It favours bone ingrowth, leading to good mid-term results.