Periacetabular cortical and cancellous bone mineral density loss after press-fit cup fixation: a prospective 7-year follow-up

Change in CT-measured acetabular bone density following total hip arthroplasty: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Assessing peri-acetabular bone quality is valuable for optimizing the outcomes of primary total hip arthroplasty (THA) as preservation of good quality bone stock likely affects implant stability. The aim of this study was to perform a meta-analysis of peri-acetabular bone mineral density (BMD) changes over time measured using quantitative computer tomography (CT) and, second, to investigate the influence of age, sex, and fixation on the change in BMD over time.

METHODS

A systematic search of Embase, Scopus, Web of Science, and PubMed databases identified 19 studies that measured BMD using CT following THA. The regions of interest (ROI), reporting of BMD results, and scan protocols were extracted. A meta-analysis of BMD was performed on 12 studies that reported measurements immediately postoperatively and at follow-up.

RESULTS

The meta-analysis determined that periacetabular BMD around both cemented and uncemented components decreases over time. The amount of BMD loss increased relative to proximity of the acetabular component. There was a greater decrease in cortical BMD over time in females and cancellous BMD for young patients of any sex.

CONCLUSION

Peri-acetabular BMD decreases at different rates relative to its proximity to the acetabular component. Cancellous BMD decreases more in young patients and cortical bone decreases more in females. Standardized reporting parameters and suggested ROI to measure peri-acetabular BMD are proposed, to enable comparison between implant and patient variables in the future.

Long-term follow-up of a low profile, coated, press-fit cup: the trabeculae oriented pattern (T.O.P.) acetabular system

Purpose

Total hip arthroplasties (THAs) are rising worldwide, as the functional request of patients who undergo this procedure. The trabeculae oriented pattern (TOP) is a modern cup, which follows the philosophy of the tissue sparing surgery (TSS). Focusing on clinical and radiological results and complications, the authors aim to highlight the outcomes of the TOP at a long-term follow-up (FU).

Methods

A retrospective analysis was completed on THA performed with the TOP cup between 1997 and 2015. Five hundred and eighty-eight patients sustained surgery, for a total of 662 cup implanted. Four hundred and sixty patients (524 hips) were examined. Mean FU was 12 ± 4.9 years (range 5–22). Clinical (HHS, OHS and VAS) and radiological data were obtained. Every complication, reoperation or revision was recorded and analyzed.

Results

Clinical evaluation revealed a HHS of 87.1 ± 13.8 an OHS of 41.3 ± 5.4, and a VAS of 1.2 ± 1.1. Acetabular osteolysis was observed in 53 hips. Overall survival rate of the cup was 90.5% (50 revisions), the main causes of cup substitution being aseptic loosening (AL) of the cup combined with the stem (26), of the cup only (13 cases) and periprosthetic joint infection (7 cases).

Conclusion

TOP cup has demonstrated a good overall survivorship at a long-term FU, even compared with other coated cups, providing excellent clinical result with low rate of complications. Its association with a neck sparing stem permits a physiologic load transmission, reducing the stress shielding effect that could cause early implant mobilization.

Ceramic-on-ceramic articulation in press-fit total hip arthroplasty as a potential reason for early failure, what about the survivors: a ten year follow-up

PURPOSE

In press-fit total hip arthroplasty (THA), primary stability is needed to avoid micromotion and hereby aseptic loosening, the main reason for early revision. High aseptic loosening revision rates of the seleXys TH+ cup (Mathys Medical) with Ceramys ceramic-on-ceramic (CoC) bearing are seen in literature. Since CoC is presumed to overcome long-term wear-related revisions, the reason for early failure of this cup is important to clarify. The aim is to investigate its ten year outcomes and differentiate between potential causes and identify risk factors for aseptic loosening.

METHODS

Retrospective screening of a prospectively documented series of 315 THAs was performed. Primary outcome was cumulative incidence of cup revision due to aseptic loosening. Secondary outcomes were component revision and reoperation. Additionally, potential predictive factors for aseptic loosening were evaluated.

RESULTS

At the median follow-up of 9.7 years [IQR 4.4; 10.3], 48 TH+ (15.2%) were revised due to aseptic loosening. Competing risk analysis showed a ten year cumulative incidence of cup revision due to aseptic loosening of 15.6% (95% CI 12.0-20.2). Stabilization of early revision rates was observed, following a high rate of respectively 81.3% (n = 39) and 95.8% (n = 46) within the first two and three years. No significant predictive factors for aseptic loosening were found.

CONCLUSION

The ten year results of seleXys TH+ cup with Ceramys CoC bearing showed an unacceptable high aseptic loosening rate, which stabilized over time after a high early failure incidence. This could be attributed to a problem with osseointegration during the transition of primary to definitive stability.

Changes in periacetabular bone mineral density five years after resurfacing hip arthroplasty versus conventional total hip arthroplasty

INTRODUCTION:

We studied whether acetabular bone mineral density (BMD) is better preserved after resurfacing hip arthroplasty (RHA) versus small diameter metal-on-metal total hip arthroplasty (THA).

METHODS:

This randomised controlled trial included 82 patients. BMD was measured in 5 periprosthetic regions of interest (ROI) with dual-energy absorptiometry (DEXA) preoperatively, at 3 and 6 months, 1, 2, 3 and 5 years postoperative. 34 RHA and 26 THA had a complete 5 years follow-up. 1 RHA and 1 THA were revised due to pseudotumour formation, 2 THA were revised because of recurrent dislocations and 1 RHA for avascular necrosis.

RESULTS:

Overall an initial decrease in BMD was observed for both implants, stabilising after 2 years. 5 years after RHA a BMD change of +1% in upper cranial, -4% ( p < 0.01) in cranial, -8% ( p < 0.01) in craniomedial, -7% ( p < 0.01) in medial and +4% in caudal ROI compared to baseline values was seen. 5 years after THA a BMD change of -3% ( p = 0.01), -13% ( p < 0.01), -21% ( p < 0.01), -11% ( p < 0.01) and -2% for each respective ROI. The observed BMD decrease in different regions was structurally favouring the RHA-cup, with significantly higher levels in the cranial and craniomedial ROI.

CONCLUSION:

Acetabular BMD is better preserved behind a rigid press-fit convex cup in RHA compared to a titanium threaded cup in conventional THA in the cranial and craniomedial ROI. Despite of a theoretical higher stress-shielding behind the stiff acetabular component in RHA, compared to the more elastic threaded titanium THA-cup, bone depletion behind the RHA component does not seem to be of major concern.

REGISTRATION:

EudraCT (2006-005610-12).

Bone density measurements adjacent to acetabular cups in total hip arthroplasty using dual-energy CT: an in vivo reliability and agreement study

Background

Measuring bone mineral density (BMD) around acetabular prosthetic components with computed tomography (CT) is challenged by the complex anatomy and metal artifacts. Three-dimensional (3D) segmentation is required for the analysis, but it is usually not practically applicable on current CT workstations

Purpose

To test the between-scan agreement and reliability of custom segmentation software for BMD measurements adjacent to cemented and uncemented acetabular cups in dual-energy CT (DECT).

Material and Methods

Twenty-four male patients with total hip arthroplasty were scanned and rescanned using 130-keV virtual monochromatic DECT images. Hemispherical regions of interest were defined slice-by-slice and BMD was calculated around the acetabular cup using custom segmentation software.

Results

In the uncemented cup, the mean BMD was 153 mg/cm³ with a between-scan difference of 10 mg/cm³ (P < 0.0001). In the cemented cup, the mean BMD was 186 mg/cm³ with a between-scan difference of 6 mg/cm³ (P = 0.15). In both uncemented and cemented cups the intraclass correlation coefficient between repeated measurements was >0.95 and narrow Bland–Altman Limits of Agreement.

Conclusion

BMD can be measured with high absolute between-scan agreement and good reliability adjacent to acetabular cemented and uncemented cups using DECT and segmentation software.

Intra- and inter-observer agreement and reliability of bone mineral density measurements around acetabular cup: a porcine ex-vivo study using single- and dual-energy computed tomography

Background

Periprosthetic bone loss is considered to be a potentially contributing factor in aseptic loosening of acetabular hip components, but no studies have shown this association. The lack of association might be caused by insufficient image quality because of metal artifacts and challenges in measuring bone density (BMD) in complex anatomic structures which might be overcome using dual-energy computed tomography (DECT).

Purpose

To test inter- and intra-observer agreement and reliability of in-house segmentation software measuring BMD adjacent to acetabular cup and to compare measurements performed with single-energy CT (SECT) and DECT in cemented and cementless cups.

Material and Methods

Twenty-four acetabular cups inserted in porcine hip specimens were scanned with SECT and DECT. Bone density was measured in a three-dimensional volume adjacent to the cup. Double measurements were performed.

Results

BMD derived from SECT was approximately four times higher than that of DECT. In both scan modes, intraclass correlation coefficient (ICC) was >0.90 with no differences between repeated measurements, except for uncemented cups where a statistically significant difference of 11 mg/cm³ was found with DECT. DECT showed narrower limits of agreement than SECT. Inter-observer analysis showed small differences.

Conclusion

BMD can be estimated with high intra- and inter-observer reliability with SECT and DECT around acetabular cups using custom software. The intra- and inter-observer agreement of DECT is superior to that of SECT and better in the cementless concept. Good intra- and inter-observer reliability can be obtained in both cemented and cementless cups using the segmentation software. SECT and DECT cannot be used interchangeably.

Agreement and precision of periprosthetic bone density measurements in micro-CT, single and dual energy CT

The objective of this study was to test the precision and agreement between bone mineral density measurements performed in micro CT, single and dual energy computed tomography, to determine how the keV level influences density measurements and to assess the usefulness of quantitative dual energy computed tomography as a research tool for longitudinal studies aiming to measure bone loss adjacent to total hip replacements. Samples from 10 fresh-frozen porcine femoral heads were placed in a Perspex phantom and computed tomography was performed with two acquisition modes. Bone mineral density was calculated and compared with measurements derived from micro CT. Repeated scans and dual measurements were performed in order to measure between- and within-scan precision. Mean density difference between micro CT and single energy computed tomography was 72 mg HA/cm³ . For dual energy CT, the mean difference at 100 keV was 128 mg HA/cm³ while the mean difference at 110-140 keV ranged from -84 to -67 mg HA/cm³ compared with micro CT. Rescanning the samples resulted in a non-significant overall between-scan difference of 13 mg HA/cm³ . Bland-Altman limits of agreement were wide and intraclass correlation coefficients ranged from 0.29 to 0.72, while 95% confidence intervals covered almost the full possible range. Repeating the density measurements for within-scan precision resulted in ICCs >0.99 and narrow limits of agreement. Single and dual energy quantitative CT showed excellent within-scan precision, but poor between-scan precision. No significant density differences were found in dual energy quantitative CT at keV-levels above 110 keV. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1470-1477, 2017.

Increase in physical activity after resurfacing hip arthroplasty is associated with calcar and acetabular bone mineral density changes

PURPOSE

Bone preservation is an important advantage of the resurfacing hip arthroplasty (RHA) concept. We hypothesised that patients' increase in physical activity level after RHA would positively relate with periprosthetic bone mineral density (BMD) changes and thus facilitate bone preservation.

METHODS

BMD-changes were prospectively recorded in 38 patients after RHA. Dual-energy absorptiometry was used to quantify BMD-changes in 6 periprosthetic regions of interest preoperatively, at 6 months, 1, 2 and 3 years postoperative. The effect estimates of patients' physical activity, according to their Harris Hip Score (HHS) and University of California at Los Angeles (UCLA) Activity Score, on these BMD changes were assessed in linear mixed models.

RESULTS

The UCLA (coefficient = 0.02 (95% CI, 0.010-0.034); p<0.001) and HHS (coefficient = 0.002 (95% CI, 0.001-0.003); p<0.001) were associated with the BMD in the calcar region. As for BMD changes in the femoral neck only the HHS was associated (coefficient = 0.0006 (95% CI, <0.0001-0.001); p = 0.04). Both the UCLA and the HHS were inversely associated with BMD in the medial acetabular region (UCLA: coefficient = -0.02 (95% CI, -0.038 to -0.007); p = 0.005, HHS: coefficient = -0.002 (95% CI, -0.003 to -0.001), the same accounted for the HHS to BMD-change cranial to the acetabulum (-0.001 [95% CI, -0.0018 to -0.0001]; p = 0.03). For the caudal acetabular and femoral subtrochanteric region no relation with BMD-changes was found.

CONCLUSIONS

The increase in activity scores after RHA was indeed associated with an increase in BMD in the calcar region, however unexpectedly also with a BMD decrease on the acetabular side. Stress shielding from the implant is the most likely causative factor.

Avaliação radiográfica e tomográfica de cães submetidos à artroplastia coxofemoral total híbrida

RESUMO A artroplastia total da articulação coxofemoral é a técnica cirúrgica mais efetiva para o tratamento da displasia coxofemoral canina grave. Na atualidade, o exame radiográfico é o método mais utilizado para se avaliar esse procedimento em cães, porém possui algumas limitações. Já o exame tomográfico por meio de tomografia computadorizada possibilita a aquisição de imagens sem sobreposições e, dessa forma, a determinação do posicionamento dos componentes protéticos com maior precisão. A presente pesquisa teve como objetivo avaliar, por meio de exames radiográficos e tomográficos, a utilização de uma prótese total modular híbrida da articulação coxofemoral desenvolvida e confeccionada no Brasil, aplicada experimentalmente em cães sadios. Foram utilizados seis cães esqueleticamente maduros, previamente submetidos ao procedimento cirúrgico da articulação coxofemoral esquerda. Os cães foram submetidos ao exame tomográfico aos 360 dias e três anos após a cirurgia. Todos os animais apresentaram bom posicionamento dos componentes protéticos e redução articular adequada. Ao exame tomográfico, entretanto, foram detectadas áreas de preenchimento irregular em alguns animais. Adicionalmente, o exame tomográfico permitiu a detecção e monitoração de áreas de reabsorção óssea ao redor do componente acetabular. Assim, o exame tomográfico mostrou-se útil na avaliação das articulações protéticas, com a vantagem de apresentar ótima definição das imagens e permitir quantificar alterações periprotéticas e mensurar relações articulares, fundamentais para o acompanhamento pós-cirúrgico tardio.

Porous titanium construct cup compared to porous coated titanium cup in total hip arthroplasty. A randomised controlled trial

PURPOSE

The purpose of this study was to determine if a new titanium cup with increased porosity resulted in different periacetabular bone loss and migration compared to a porous coated cup.

METHODS

Fifty-one patients with primary hip osteoarthritis were randomized to either a cup with porous titanium construct backside (porous titanium group, n = 25) or a conventional porous coated titanium cup (control group, n = 26). The primary outcome variable was change in periacetabular bone mineral density two years after surgery measured with dual energy X-ray absorptiometry (DXA). Secondary outcomes were implant fixation measured with radiostereometry (RSA) and clinical outcome scores.

RESULTS

The pattern of bone remodelling was similar in the two groups with almost complete restoration to baseline values. BMD diminished in the two proximal zones and increased in the two distal zones. After minimal migration up to six months all implants in both groups became stable. We found no difference between the two groups in clinical outcome scores.

CONCLUSIONS

In this prospective, randomized, controlled trial on a new porous titanium cup we found, compared to the control group, no clinically relevant differences regarding periacetabular bone preservation, implant fixation or clinical outcome up to two years postoperatively.

No superior performance of hydroxyapatite-coated acetabular cups over porous-coated cups

BACKGROUND AND PURPOSE

Hydroxyapatite (HA) coating is believed to improve bone-implant ingrowth and long-term survival of prostheses. Recent studies, however, have challenged this view. Furthermore, HA particles may produce third-body wear and initiate aseptic loosening of implants. We report the performance of HA- and porous-coated acetabular cups in a prospective randomized trial.

METHODS

This was an 8-year follow-up study of our previously published prospective randomized study to compare clinical outcomes, survival, periprosthetic bone mineral density, migration, and wear rates of HA- and porous-coated acetabular cups. Dual X-ray absorptiometry (DXA) and Ein Bild Roentgen Analyse (EBRA) measurements were used. 100 patients who underwent unilateral cementless total hip arthroplasty were randomized to either porous-coated cups or HA-coated cups. Patients were examined preoperatively and at 3, 6, and 9 months, and also 1, 3, and 8 years after surgery. 81 patients were available for 8-year follow-up, 40 with porous-coated cups and 41 with HA-coated cups.

RESULTS

Age, sex, bone mineral density, and clinical results (Harris hip score) were similar in the 2 groups. The survival, wear, and migration patterns of the cups were also similar in both groups. The results of periprosthetic bone mineral density scans in region of interest 2 was in favor of the porous-coated cups, but there were no differences between the 2 groups in all the remaining regions of interest.

INTERPRETATION

HA coating had no statistically significant effect on clinical results, survival, wear, or migration at the 8-year follow-up.