Outcome of a hemispherical porous-coated acetabular component with a proximally hydroxyapatite-coated anatomical femoral component

Influence of highly cross-linked polyethylene manufacturing characteristics on femoral head penetration in total hip arthroplasty : a ten- to 22-year follow-up study

Aims

Highly cross-linked polyethylene (HXLPE) has reduced wear and revision rates in total hip arthroplasty (THA) in the long term. However, the effect of HXLPE manufacturing characteristics on femoral head penetration has not yet been clearly defined. We report this single-institution study to investigate the clinical and radiological results of various HXLPE liners in THA.

Methods

Between January 2001 and December 2013, 904 uncemented THAs using HXLPE liners were performed at our institution. Seven different HXLPE liner types were identified: remelted (n = 3), annealed (n = 2), sequentially annealed (n = 1), and vitamin E diffused (n = 1). A total of 746 hips were available for a minimum follow-up of ten years. The linear femoral head penetration rate was measured at six weeks and at one, five, ten, and 15 years, applying the Dorr criteria to digitized radiographs, using the Roman v. 1 70 software package for analysis.

Results

No patient was revised due to wear or osteolysis. The mean total femoral head penetration ten years after THA ranged from 0.14 mm (SD 0.06) to 0.20 mm (SD 0.17) for all groups (p = 0.649). Femoral head penetration > 0.40 mm at ten years was observed in 27 (3.6%) hips. From one to 15 years after surgery, mean total penetration was 0.21 mm (SD 0.13) in components with an acetabular inclination > 50° and 0.10 mm (SD 0.12) in those placed between 35° and 50° (p < 0.001). The radiological analysis did not detect osteolysis in any hip.

Conclusion

Although HXLPE characteristics can result in different wear performance in patients undergoing THA at a mean follow-up of 15 years, the clinical and radiological results were excellent in all groups. The position of the acetabular component can influence the femoral head penetration of modern HXLPEs.

Cementless acetabular component without screw holes with immediate full weightbearing : a minimum 20-year follow-up study

Aims

This study aimed to evaluate the survival of a cementless component without screw holes in total hip arthroplasty (THA) at a minimum follow-up of 20 years. This design has the benefits of maximizing bone contact and reducing osteolysis by eliminating channels to backside wear. However, transacetabular screws cannot be used.

Methods

A total of 71 hips in 58 patients receiving the same model of cementless component without screw holes (Depuy Duraloc 100 hydroxyapatite (HA) component) from June 1999 to March 2003 were prospectively followed up. All patients were allowed to have immediate full weightbearing. The mean age at THA was 53.7 years (28 to 74). Osteonecrosis was the leading cause of THA. Survival was assessed with any revision and component revision as the endpoint. Radiological parameters, including lateral opening angle, and the components' vertical and horizontal migration distances, were measured and compared between the early postoperative period and final follow-up.

Results

Overall, 54 hips were assessed at a minimum 20-year follow-up. The mean follow-up was 22.9 years (20.9 to 24.5). Two component revisions occurred at 17.5 and 17.6 years later. Both components were well fixed but were revised, due to the need to upsize the articulation and component malpositioning, respectively. Conventional polyethylene (PE) was used in both hips, and 14 other hips were revised with the components well fixed and not revised. The estimated survival of the acetabular component and THA at 20 years was 96.4% and 74.5%, respectively. Mean changes in lateral opening angle and vertical and horizontal migration distances were 0.48° (SD 1.45°), -0.06 mm (SD 1.44), and -0.36 mm (SD 1.36), respectively, with no statistical significance.

Conclusion

This study provides evidence of excellent long-term survival of cementless components without screw holes. Immediate postoperative weightbearing did not lead to component migration in the long term.

Hydroxyapatite-coated total primary hip replacement: 28-year follow-up survivorship

BACKGROUND

Survival at 25 years' follow-up for total hip arthroplasty (THA) has been reported at 5%-77%, with hydroxyapatite (HA) coating, due to its osteo-conductive properties, used to enhance implant fixation and survival. The progressive increase in life expectancy raises doubts regarding HA-coated THA survival and THA revision surgery risk. The aim of our study was to retrospectively analyse survival for primary uncemented fully HA-coated THA after 28 years' follow-up.

METHODS

Our cohort survival study of the JRI Furlong HA-coated system retrospectively included patients aged 18-75 years who had undergone THA between 1992 and 1998 at our centre and who were followed up according to clinical records by orthopaedic surgeons to 2022. Data on THA revision surgery and its causes, follow-up, and death were analysed using Kaplan-Meier survival and Cox regression modelling.

RESULTS

The cohort included 196 patients (268 hips) followed up to a maximum of 27.5 years (mean 15.54 (SD 6.01) years) with 62 patients (88 hips) >25 years. THA revision surgery was performed in 7.5% of cases, occurring a mean of 11.1 years following primary surgery. Aseptic loosening accounted for 4.4% of these revisions, affecting both the acetabular component (2.2%) and the femoral stem (1.3%). THA survival at 15 years', 20 years', and 27.5 years' follow-up was 95.5%, 88.3%, and 79.3%, respectively. According to the log-rank and Cox regression analysis, no significant relationships were found.

CONCLUSIONS

Furlong HA-coated stem provides excellent long-term bone fixation for a long-term follow-up over 27.5 years with an aseptic loosening stem revision rate of 1.3%.

The bone trauma and soft-tissue injury classification system in total hip arthroplasty (BOSTI Hip)

Aims

The primary objective of this study was to develop a validated classification system for assessing iatrogenic bone trauma and soft-tissue injury during total hip arthroplasty (THA). The secondary objective was to compare macroscopic bone trauma and soft-tissues injury in conventional THA (CO THA) versus robotic arm-assisted THA (RO THA) using this classification system.

Methods

This study included 30 CO THAs versus 30 RO THAs performed by a single surgeon. Intraoperative photographs of the osseous acetabulum and periacetabular soft-tissues were obtained prior to implantation of the acetabular component, which were used to develop the proposed classification system. Interobserver and intraobserver variabilities of the proposed classification system were assessed.

Results

The BOne trauma and Soft-Tissue Injury classification system in total Hip arthroplasty (BOSTI Hip) grades osseous acetabular trauma and periarticular muscle damage during THA. The classification system has an interclass correlation coefficient of 0.90 (95% CI 0.86 to 0.93) for interobserver agreement and 0.89 (95% CI 0.84 to 0.93) for intraobserver agreement. RO THA was associated with improved BOSTI Hip scores (p = 0.002) and more pristine osseous surfaces in the anterior superior (p = 0.001) and posterior superior (p < 0.001) acetabular quadrants compared with CO THA. There were no differences between the groups in relation to injury to the gluteus medius (p = 0.084), obturator internus (p = 0.241), piriformis (p = 0.081), superior gamellus (p = 0.116), inferior gamellus (p = 0.132), quadratus femoris (p = 0.208), and vastus lateralis (p = 0.135), but overall combined muscle injury was reduced in RO THA compared with CO THA (p = 0.023).

Discussion

The proposed BOSTI Hip classification provides a reproducible grading system for stratifying iatrogenic bone trauma and soft-tissue injury during THA. RO THA was associated with improved BOSTI Hip scores, more pristine osseous acetabular surfaces, and reduced combined periarticular muscle injury compared with CO THA. Further research is required to understand if these intraoperative findings translate to differences in clinical outcomes between the treatment groups.

Survival and Clinical Outcomes at 30 to 35 Years Following Primary Total Hip Arthroplasty With a Cementless Femoral Stem Fully Coated With Hydroxyapatite

BACKGROUND

The purpose of the present study was to update and report clinical outcomes and survival of primary total hip arthroplasty using a cementless double-tapered titanium fully hydroxyapatite-coated stem at a follow-up > 30 years.

METHODS

The outcomes of this series of 347 primary total hip arthroplasties were already published at a follow-up > 25 years, during which only 12 stems were revised. Since then, there were two additional stem revisions, bringing the total to 14 stem revisions (all of which also required cup revision). Patients still living with the original stem were assessed using the modified Harris Hip Score and patient satisfaction (very satisfied, satisfied, dissatisfied, and very dissatisfied). Revision incidence was calculated using the Kaplan-Meier (KM) method and Cumulative Incidence Function (CIF) at 35 years.

RESULTS

At a mean follow-up of 33 years (range, 31 to 35 years), 32 patients (34 hips) were still living with the original stem. Their mean modified Harris Hip Score was 86 points (range, 46 to 100) and all patients (100%) were very satisfied or satisfied with surgery. The revision incidence at 35 years considering (a) stem revision for any reason was 9.5% using KM and 4.5% using CIF; (b) stem revision for aseptic loosening was 3.1% using KM and 2.1% using CIF; and (c) reoperation or revision of any component for any reason was 45.3% using KM and 26.3% using CIF.

CONCLUSION

The present study has demonstrated excellent survival at 35 years for a cementless double-tapered titanium fully hydroxyapatite-coated stem.

LEVEL OF EVIDENCE

Level IV, Retrospective cohort study.

New polyethylenes in total hip arthroplasty : a 20- to 22-year follow-up study

AIMS

A significant reduction in wear at five and ten years was previously reported when comparing Durasul highly cross-linked polyethylene with nitrogen-sterilized Sulene polyethylene in total hip arthroplasty (THA). We investigated whether the improvement observed at the earlier follow-up continued, resulting in decreased osteolysis and revision surgery rates over the second decade.

METHODS

Between January 1999 and December 2001, 90 patients underwent surgery using the same acetabular and femoral components with a 28 mm metallic femoral head and either a Durasul or Sulene liner. A total of 66 hips of this prospective randomized study were available for a minimum follow-up of 20 years. The linear femoral head penetration rate was measured at six weeks, one year, and annually thereafter, using the Dorr method on digitized radiographs with a software package.

RESULTS

In the Durasul group, no patients underwent revision due to loosening or showed radiological evidence of osteolysis. In the Sulene group, four patients (four hips) were revised due to femoral component loosening. The 20-year cumulative failure incidence in the presence of the competing event of death for revision surgery was 4.5% (95% confidence interval (CI) 0.8 to 13.6) in the Durasul group, and 8.9% (95% CI 2.8 to 19.5) in the Sulene group. The mean wear one year after surgery was 0.09 mm (SD 0.007) in the Durasul group and 0.24 (SD 0.015) in the Sulene group (p < 0.001). From one to 20 years after surgery, the mean total penetration was 0.32 mm (SD 0.045) in the Durasul group and 1.07 mm (SD 0.13) in the Sulene group (p < 0.001). Mean femoral head penetration at 20 years was approximately 70.0% less in the Durasul group than the Sulene group.

CONCLUSION

The significant reduction in femoral head penetration obtained with the Durasul compared with Sulene in uncemented THA resulted in lower osteolysis and revision rates after 20 years.Cite this article: Bone Joint J 2022;104-B(9):1032-1038.

Oxidized zirconium versus cobalt-chrome femoral heads in total hip arthroplasty: a multicentre prospective randomized controlled trial with ten years' follow-up

AIMS

This study reports the ten-year wear rates, incidence of osteolysis, clinical outcomes, and complications of a multicentre randomized controlled trial comparing oxidized zirconium (OxZr) versus cobalt-chrome (CoCr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) and highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA).

METHODS

Patients undergoing primary THA were recruited from four institutions and prospectively allocated to the following treatment groups: Group A, CoCr femoral head with XLPE liner; Group B, OxZr femoral head with XLPE liner; and Group C, OxZr femoral head with UHMWPE liner. All study patients and assessors recording outcomes were blinded to the treatment groups. The outcomes of 262 study patients were analyzed at ten years' follow-up.

RESULTS

Patients in Group C were associated with increased mean liner wear rates compared to patients in Group A (0.133 mm/yr (SD 0.21) vs 0.031 mm/yr (SD 0.07), respectively; p < 0.001) and Group B (0.133 mm/yr (SD 0.21) vs 0.022 mm/yr (SD 0.05), respectively; p < 0.001) at ten years' follow-up. Patients in Group C were also associated with increased risk of osteolysis and aseptic loosening requiring revision surgery, compared with patients in Group A (7/133 vs 0/133, respectively; p = 0.007) and Group B (7/133 vs 0/135, respectively; p = 0.007). There was a non-statistically significant trend towards increased mean liner wear rates in Group A compared with Group B (0.031 mm/yr (SD 0.07) vs 0.022 mm/yr (SD 0.05), respectively; p = 0.128). All three groups were statistically comparable preoperatively and at ten years' follow-up when measuring normalized Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.410), 36-Item Short Form Health Survey (p = 0.465 mental, p = 0.713 physical), and pain scale scores (p = 0.451).

CONCLUSION

The use of UHMWPE was associated with progressively increased annual liner wear rates after THA compared to XLPE. At ten years' follow-up, the group receiving UHMWPE demonstrated an increased incidence of osteolysis and aseptic loosening requiring revision surgery compared to XLPE. Femoral heads composed of OxZr were associated with trend towards reduced wear rates compared to CoCr, but this did not reach statistical significance and did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two femoral head components. Cite this article: Bone Joint J 2022;104-B(7):833-843.

Antibiotic-loaded amphora-shaped pores on a titanium implant surface enhance osteointegration and prevent infections

Artificial prostheses for joint replacement are indispensable in orthopedic surgery. Unfortunately, the implanted surface is attractive to not only host cells but also bacteria. To enable better osteointegration, a mechanically stable porous structure was created on a titanium surface using laser treatment and metallic silver particles were embedded in a hydrophilic titanium oxide layer on top. The laser structuring resulted in unique amphora-shaped pores. Due to their hydrophilic surface conditions and capillary forces, the pores can be loaded preoperative with the antibiotic of choice/need, such as gentamicin. Cytotoxicity and differentiation assays with primary human osteoblast-like cells revealed no negative effect of the surface modification with or without gentamicin loading. An in vivo biocompatibility study showed significantly enhanced osteointegration as measured by push-out testing and histomorphometry 56 days after the implantation of the K-wires into rat femora. Using a S. aureus infection model, the porous, silver-coated K-wires slightly reduced the signs of bone destruction, while the wires were still colonized after 28 days. Loading the amphora-shaped pores with gentamicin significantly reduced the histopathological signs of bone destruction and no bacteria were detected on the wires. Taken together, this novel surface modification can be applied to new or established orthopedic implants. It enables preoperative loading with the antibiotic of choice/need without further equipment or post-coating, and supports osteointegration without a negative effect of the released dug, such as gentamicin.

Posterior pelvic tilt evolution in patients undergoing total hip arthroplasty. A minimum 5-years follow-up clinico-radiological study

BACKGROUND AND OBJECTIVE

Pelvic tilt influences the relative position between total hip arthroplasty (THA) components. Changes in lumbar spine over time may affect clinical and radiological outcomes of THA during follow-up. We assessed the evolution of pelvic tilt and cup position after THA for a minimum follow-up of five years and the possible appearance of complications.

MATERIAL AND METHODS

This retrospective study includes 48 patients operated between 2008 and 2012. Clinical data, complication and radiological analysis included sacro-femoral-pubic and acetabular abduction angles on the anteroposterior pelvic view; and cup anteversion angle on the lateral cross-table hip view according to Woo and Morrey. All assessments were done pre-operatively and at 6 weeks, one, two and five years post-operatively.

RESULTS

Mean sacro-femoral-pubic decreased from 60.6∘ preoperatively to 58.8∘ at five years (p > .05), more in females (from 63.3 to 59.3) than males (58.7 to 58.3). Acetabular abduction increased from 47.3 at six-week postoperatively to 48.2 at five years (p > .05) and acetabular anteversion varied from 24.3∘ to 36.1∘ (p < .04). There were four dislocations: one late recurrent dislocation which required cup revision.

CONCLUSION

Despite the sacro-femoral-pubic angle tendency to decrease and anteversion tendency to increase after five years, larger studies with longer follow-up are needed to confirm the potential increasing in long term complications.

Stress shielding at the bone-implant interface: Influence of surface roughness and of the bone-implant contact ratio

Short and long-term stabilities of cementless implants are strongly determined by the interfacial load transfer between implants and bone tissue. Stress-shielding effects arise from shear stresses due to the difference of material properties between bone and the implant. It remains difficult to measure the stress field in periprosthetic bone tissue. This study proposes to investigate the dependence of the stress field in periprosthetic bone tissue on (i) the implant surface roughness, (ii) the material properties of bone and of the implant, (iii) the bone-implant contact ratio. To do so, a microscale two-dimensional finite element model of an osseointegrated bone-implant interface was developed where the surface roughness was modeled by a sinusoidal surface. The results show that the isostatic pressure is not affected by the presence of the bone-implant interface while shear stresses arise due to the combined effects of a geometrical singularity (for low surface roughness) and of shear stresses at the bone-implant interface (for high surface roughness). Stress-shielding effects are likely to be more important when the bone-implant contact ratio value is low, which corresponds to a case of relatively low implant stability. Shear stress reach a maximum value at a distance from the interface comprised between 0 and 0.1 time roughness wavelength λ and tend to 0 at a distance from the implant surface higher than λ, independently from bone-implant contact ratio and waviness ratio. A comparison with an analytical model allows validating the numerical results. Future work should use the present approach to model osseointegration phenomena.

Long-Term results of total Hip Arthroplasty performed using a cementless expansive Acetabular Cup and Spotorno Femoral Stem

Objective

In this study we aimed to investigate the long-term clinical and radiological results, revision rates and causes, and the rate of implant survival in total hip arthroplasty performed using CLS^® expansion cup and Spotorno^® cementless femoral stem.

Methods

Clinical results of total hip arthroplasty performed on 131 hips of 114 patients in Istanbul Training and Research Hospital between 1993 and 2003 were retrospectively evaluated according to the Harris Hip Score. Revision rates were determined and implant survival rates were identified using the Kaplan-Meier estimator.

Results

Of the patients, 39 were males and 75 were females. The average age of the patients at surgery was 48.7±11.3 years. Patients were followed up for a mean period of 13.9±2.4 years. The mean Harris Hip Score was 34.35±6.09 preoperatively and 88.20±7.11 at the final follow-up (p<0.001). The Kaplan-Meier survivorship estimate for the cup at 13.9 years, taking revision for any reason as the end point was 95.6% (95% CI), while the 15^th and 17^th year survival rates were 90% and 85%, respectively.

Conclusion

In total hip arthroplasty using a cementless expansive acetabular cup, a 95.6% survival rate is achieved after an average of 14 years, whereas the rate decreases to 85% after 17 years. Even if the incidence of cup breakage is reduced with proper implantation, particle disease and periacetabular osteolysis remains a problem for the long-term survival.

Bone remodeling, around an anatomical hip stem: a one year prospective study using DEXA

INTRODUCTION

The loss of bone mass, as a consequence of bone remodelling, in the proximal third of the femur, is a factor that contributes to the failure of hip prostheses in the medium to long term. This periprosthetic remodelling occurs mainly during the first 12 months after the operation. The aim is to evaluate the behaviour at one year of a new anatomical stem, the ANATO® stem (2015-Stryker®), which is a redesign of its predecessor (ABG-ii®-Stryker stem) by means of bone densitometry.

METHOD

Prospective, controlled study in which the changes in bone mineral density (BMD) observed around the seven areas of Gruen in a group of 61 patients affected by primary coxarthrosis, in whom an ANATO® stem was implanted, are analysed densitometrically. The healthy hip was taken as the control group. The existence of differences in the remodelling pattern according to sex, age and body mass index (BMI) was compared. The follow-up was during the first year after the intervention.

RESULTS

After one year of follow-up, decreases of bone mineral density in zone seven of -5.9% were observed, being this decrease statistically significant. No differences were found in the remodelling pattern according to age, sex and body mass index.

CONCLUSION

The ANATO® stem allows an efficient transmission of loads from the stem to the proximal femur. Only in zone seven significant bone atrophy is observed. Differences in age, BMI and sex do not seem to influence the bone remodelling around this new stem.