Long-term results of a hydroxyapatite-coated femoral component in total hip replacement: a 15- to 21-year follow-up study

Outcomes of a hydroxyapatite ceramic-coated femoral stem in primary total hip arthroplasty: a report of excellent survivorship from a single United Kingdom centre

BACKGROUND

Hydroxyapatite (HA) coated femoral stems were introduced to enhance the biological fixation at the implant-bone interface, aiming to increase the longevity and survival of the prostheses. We aimed to assess the long-term outcomes of an HA ceramic (HAC) coated stem in primary total hip arthroplasty (THA), assess the stem survival, and clinically evaluate the patients using patient-reported outcome measures (PROMs) and radiological evaluation of stem osseointegration.

PATIENTS AND METHODS

This was a prospective evaluation of a retrospective cohort of 385 patients (442 hips) who underwent primary THA between June 2008 and December 2018. The mean age was 63.83 years (range, 30-82 years). During the follow-up duration, 23 patients died, and 36 patients (38 hips) were lost to follow-up. Prospective data collected for 326 patients (381 hips) was used to evaluate stem survival with the Kaplan-Meier method using aseptic loosening or any revision as the endpoint. Clinical evaluation was done using the EuroQol five-dimension (EQ-5D) scoring system and PROMs using the Oxford Hip Score (OHS) and Merle D'Aubigne Postel (MDP) score. Radiological assessments were performed using the Engh radiological criteria for stem osteointegration.

RESULTS

The mean follow-up duration was 9.39 years (range, 4-14.5 years). The survival of the HAC-coated femoral stem was 100% (95% confidence interval [CI], 96.7-100%) at 14 years with aseptic loosening as the endpoint, and 98.9% (CI, 96.7-100%) at 14 years with stem revision for any reason as the endpoint. The mean OHS was 44.5 (range, 30-48), and the mean MDP score was 15.87 (range, 10-18). Radiological evaluations showed full osseointegration of all stems.

CONCLUSION

This HAC-coated femoral stem has shown excellent survivorship, functional outcomes, and full osseointegration at the final follow-up.

Total Hip Replacement with a Fully Hydroxyapatite-Coated Shortened Stem: Five- to Thirteen-Year Follow-Up Results

Background: Shortened femoral stems aim to mimic the biomechanical performance of traditional stems while preserving more bone and minimizing soft tissue damage. Our objective is to assess the outcomes of patients treated with a shortened stem (Furlong Evolution, JRI Orthopaedics, Sheffield, UK) to analyze the implant's efficacy and survivorship. Methods: This retrospective observational study included all patients aged 18 to 70 undergoing uncemented shortened stem total hip replacement at Hospital del Mar between 2010 and 2018. Hip function and pain were assessed with the Merle d'Aubigné-Postel scale and visual analog scale, respectively. A radiographic analysis measured stem and cup orientation, leg length discrepancy, stem subsidence, and radiolucencies around the cup. Perioperative complications, prosthetic failures, and reoperations were documented. Results: A total of 109 patients (74 male, 35 female) of a mean age of 51.8 ± 8.8 years were included. The average follow-up was 91 ± 17.4 months. Radiographically, 71 (65.1%) of the stems had been inserted at the appropriate angulation (±3°), and 102 (93.6%) of the cups had been placed in the Lewinnek safety zone. Leg length discrepancy was observed in 19 (17.4%) cases. The mean Merle d'Aubigné-Postel score improved from 13.1 ± 1.39 preoperatively to 17.8 ± 0.49 at 6 months postoperatively (p < 0.001). Merle d'Aubigné-Postel subscales also reflected a statistically significant improvement (p < 0.001). The mean pain score 12 months postoperatively was 0.52 ± 1.22, with 95.4% of patients declaring themselves satisfied or highly satisfied. The expected 13-year survival according to a Kaplan-Meier analysis was 100% in the absence of infection and 91.3% if revision for any cause is taken as a survival endpoint. Conclusions: The shortened stem under analysis provides excellent functional results and long-term survival rates.

5 year follow up of a hydroxyapatite coated short stem femoral component for hip arthroplasty: a prospective multicentre study

Short stem, uncemented femoral implants for hip arthroplasty are bone conserving achieving stability through initial metaphyseal press-fit and biological fixation. This study aimed to evaluate the survivorship, mid-term function and health related quality of life outcomes in patients who have undergone total hip arthroplasty (THA) with a fully hydroxyapatite coated straight short stem femoral component with up to 5 years follow-up. 668 patients were recruited to a multicentre study investigating the performance of the cementless Furlong Evolution® stem for THA. 137 patients withdrew at various time points. The mean follow-up was 49 months. Clinical (Harris Hip Score (HHS), radiographic and patient-reported outcome measures-Oxford Hip Score (OHS) and EuroQol 5D (EQ-5D), were recorded pre-operatively and at 6 weeks, 6 months, 1 year, 3 year and 5 year follow ups. At 5-year follow-up, 12 patients underwent revision surgery, representing a cumulative revision rate of 1.8%. Median OHS, HHS and EQ5D scores improved significantly: OHS improved from a pre-operative median of 21 (IQR 14-26) to 47 (IQR 44-48) (p < 0.001). HHS improved from 52 (IQR 40-63) to 98 (IQR 92-100) (p < 0.001) and EQ5D improved from 70 (IQR 50-80) to 85 (IQR 75-95) (p < 0.001). This fully HA-coated straight short femoral stem implant demonstrated acceptable mid-term survivorship and delivered substantial improvements in function and quality of life after THA.

There Are over 60 Ways to Produce Biocompatible Calcium Orthophosphate (CaPO4) Deposits on Various Substrates

A The present overview describes various production techniques for biocompatible calcium orthophosphate (abbreviated as CaPO4) deposits (coatings, films and layers) on the surfaces of various types of substrates to impart the biocompatible properties for artificial bone grafts. Since, after being implanted, the grafts always interact with the surrounding biological tissues at the interfaces, their surface properties are considered critical to clinical success. Due to the limited number of materials that can be tolerated in vivo, a new specialty of surface engineering has been developed to desirably modify any unacceptable material surface characteristics while maintaining the useful bulk performance. In 1975, the development of this approach led to the emergence of a special class of artificial bone grafts, in which various mechanically stable (and thus suitable for load-bearing applications) implantable biomaterials and artificial devices were coated with CaPO4. Since then, more than 7500 papers have been published on this subject and more than 500 new publications are added annually. In this review, a comprehensive analysis of the available literature has been performed with the main goal of finding as many deposition techniques as possible and more than 60 methods (double that if all known modifications are counted) for producing CaPO4 deposits on various substrates have been systematically described. Thus, besides the introduction, general knowledge and terminology, this review consists of two unequal parts. The first (bigger) part is a comprehensive summary of the known CaPO4 deposition techniques both currently used and discontinued/underdeveloped ones with brief descriptions of their major physical and chemical principles coupled with the key process parameters (when possible) to inform readers of their existence and remind them of the unused ones. The second (smaller) part includes fleeting essays on the most important properties and current biomedical applications of the CaPO4 deposits with an indication of possible future developments.

The influence of hydroxyapatite coating on continuous migration of a Zweymuller-type hip stem: a double-blinded randomised RSA trial with 5-year follow-up

BACKGROUND AND PURPOSE

Adding hydroxyapatite to a stem to enhance ingrowth is a matter of debate, even less is known about the long-term effect on stability by adding hydroxyapatite (HA). Continuous migration in the first 2-5 years is an indicator of failed osteointegration or pending failure, enhancing the risk of loosening within 10 years after initial surgery. We performed a double-blinded randomised RSA trial with 5-year follow-up, to compare and analyse migration characteristics of the hydroxyapatite uncoated (HA-) and hydroxyapatite coated (HA+) Zweymuller-type hip stem.

PATIENTS AND METHODS

In this single-centre prospective randomised controlled trial 51 patients were randomised to receive either a HA- or a HA+ Zweymuller-type hip stem during total hip replacement. After 5 years, 35 patients were still eligible for follow-up evaluation. The migration pattern was measured by use of radio stereometric analysis (RSA) images up to 2 years to evaluate short-term migration, additionally RSA images were obtained 5 years postoperatively to assess late-term and continuous migration. Furthermore, the improvement of clinical outcome was analysed by HSS and HOOS ADL and pain subscales preoperative and after 5 years.

RESULTS

After initial settling of the implant, no significant migration occurred up to 5 years post-surgery for HA+ as well as HA- prostheses. Continuous migration within the 2-5 years' time interval was not observed for both HA+ nor the HA- group in all directions (p < 0.05). No significant difference between both groups was observed (p < 0.10). In both groups the HHS and HOOS improved significantly at 5 years compared to baseline for both groups. Improvement was not altered by the hydroxyapatite coating. No significant difference between both groups was observed (p > 0.58).

CONCLUSIONS

Addition of a hydroxyapatite coating did not influence the migration 5 years postoperatively for the Zweymuller-type hip stem.Clinical Trial Protocol number: NL 23524.048.08.

Revisiting Cemented Femoral Fixation in Hip Arthroplasty

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The primary means of femoral fixation in North America is cementless, and its use is increasing worldwide, despite registry data and recent studies showing a higher risk of periprosthetic fracture and early revision in elderly patients managed with such fixation than in those who have cemented femoral fixation.

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Cemented femoral stems have excellent long-term outcomes and a continued role, particularly in elderly patients.

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Contrary to historical concerns, recent studies have not shown an increased risk of death with cemented femoral fixation.

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The choice of femoral fixation method should be determined by the patient's age, comorbidities, and bone quality.

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We recommend considering cemented femoral fixation in patients who are >70 years old (particularly women), in those with Dorr type-C bone or a history of osteoporosis or fragility fractures, or when intraoperative broach stability cannot be obtained.

3D Bioprinted Scaffolds for Bone Tissue Engineering: State-Of-The-Art and Emerging Technologies

Treating large bone defects, known as critical-sized defects (CSDs), is challenging because they are not spontaneously healed by the patient’s body. Due to the limitations associated with conventional bone grafts, bone tissue engineering (BTE), based on three-dimensional (3D) bioprinted scaffolds, has emerged as a promising approach for bone reconstitution and treatment. Bioprinting technology allows for incorporation of living cells and/or growth factors into scaffolds aiming to mimic the structure and properties of the native bone. To date, a wide range of biomaterials (either natural or synthetic polymers), as well as various cells and growth factors, have been explored for use in scaffold bioprinting. However, a key challenge that remains is the fabrication of scaffolds that meet structure, mechanical, and osteoconductive requirements of native bone and support vascularization. In this review, we briefly present the latest developments and discoveries of CSD treatment by means of bioprinted scaffolds, with a focus on the biomaterials, cells, and growth factors for formulating bioinks and their bioprinting techniques. Promising state-of-the-art pathways or strategies recently developed for bioprinting bone scaffolds are highlighted, including the incorporation of bioactive ceramics to create composite scaffolds, the use of advanced bioprinting technologies (e.g., core/shell bioprinting) to form hybrid scaffolds or systems, as well as the rigorous design of scaffolds by taking into account of the influence of such parameters as scaffold pore geometry and porosity. We also review in-vitro assays and in-vivo models to track bone regeneration, followed by a discussion of current limitations associated with 3D bioprinting technologies for BTE. We conclude this review with emerging approaches in this field, including the development of gradient scaffolds, four-dimensional (4D) printing technology via smart materials, organoids, and cell aggregates/spheroids along with future avenues for related BTE.

Migration pattern of a short uncemented stem with or without collar: a randomised RSA-study with 2 years follow-up

BACKGROUND

There is an increasing interest in shorter, proximally loading, uncemented femoral stems. The aim of this study was to evaluate a new short stem type, its design based on a well-proven precursor, but with several new design features to facilitate easier insertion and possible preservation of proximal bone stock. It is available with or without a collar.

METHODS

The study includes 50 patients with primary osteoarthritis, mean age 59 (range 36-75) years, randomised to receive either the collar-fitted or the collarless stem. The patients underwent repeated radiostereometry (RSA) examinations (0, 0.5, 3, 12, 24 months), conventional radiography and filled out both hip-specific (HOOS) and general health (EQ-5D) questionnaires.

RESULTS

There was no statistically significant difference between the collared and collarless stems regarding migration and clinical outcome. Both stem types exhibit a similar pattern of initial subsidence (collared 0.63 mm vs. collarless 0.75 mm [p = 0.50]) and retroversion (collared 0.71° vs. collarless 0.97° [p = 0.36]) up to 3 months followed by stabilisation, in similarity with its precursors, suggesting good osseointegration. No stem has been revised or considered loose.

CONCLUSIONS

The new design features, including shortening the stem, do not compromise migration pattern or osseointegration, regardless collar or not.

Long-Term Outcomes of 496 Anatomical Cementless Modular Femoral Stems: Eleven to Twenty Years of Follow-Up

BACKGROUND

The aim of the study is to assess the long-term outcomes of this specific stem (anatomical cementless modular stem ESOP), to review the survivorship, complication rate, and radiographic and clinical outcomes.

METHODS

Descriptive and analytical retrospective longitudinal observational study of patients was operated on total hip arthroplasty between 1998 and 2007. Four hundred ninety-six prostheses corresponding to 447 patients were reviewed, mean age was 65.8 years (standard deviation [SD] ±11.6 years), and median follow-up time was 13.4 years (range 1-20). The most used cups were cementless (75.8%). The most frequent friction pairs were metal-polyethylene (53.1%) and ceramic-polyethylene (24.2%). Main variables analyzed were stem survival, subsidence, coronal orientation, osteolysis, reintervention, and Oxford Hip Score.

RESULTS

From 496 implants, there were 22 lost to follow-up (4.4%). Stem revision was performed in 51 patients: 26 periprosthetic joint infections (2-stage revision), 16 periprosthetic fractures, and 8 one-stage revisions (6 real aseptic loosening with negative culture after revision). The stem survivorship at more than 15 years for any reason was 89.2% and for aseptic loosening 97.97%. No specific complications were found due to modularity. The mean subsidence and orientation was 2.06 mm (SD ±5.11 mm) and 0.41° varus (SD ±2.20°) respectively. Subsidence >5 mm or varus >5° was associated with a higher revision rate. Osteolysis was found in 110 patients (zone I = 79, VII = 57), associated with zirconium-polyethylene, without relationship to the stem revision rate or Oxford Hip Score.

CONCLUSION

To our knowledge, this study represents the largest series of this stem, revealing an excellent survival rate and long-term clinical outcomes similar to the best results of classical cementless stems published in the literature.

Primary stability of a proximally coated and tapered stem

AIMS

The aim of this prospective cohort study was to evaluate the early migration of the TriFit cementless proximally coated tapered femoral stem using radiostereometric analysis (RSA).

METHODS

A total of 21 patients (eight men and 13 women) undergoing primary total hip arthroplasty (THA) for osteoarthritis of the hip were recruited in this study and followed up for two years. Two patients were lost to follow-up. All patients received a TriFit stem and Trinity Cup with a vitamin E-infused highly cross-linked ultra-high molecular weight polyethylene liner. Radiographs for RSA were taken postoperatively and then at three, 12, and 24 months. Oxford Hip Score (OHS), EuroQol five-dimension questionnaire (EQ-5D), and adverse events were reported.

RESULTS

At two years, the mean subsidence of the head and tip for the TriFit stem was 0.38 mm (SD 0.32) and 0.52 mm (SD 0.36), respectively. The total migration of the head and tip was 0.55 mm (SD 0.32) and 0.71 mm (SD 0.38), respectively. There were no statistically significant differences between the three to 12 months' migration (p = 0.105) and 12 to 24 months' migration (p = 0.694). The OHS and EQ-5D showed significant improvements at two years.

CONCLUSION

The results of this study suggest that the TriFit femoral stem achieves initial stability and is likely to be stable in the mid and long term. A long-term outcome study is required to assess late mechanisms of failure and the effects of bone mineral density (BMD) related changes. Cite this article: Bone Joint J 2021;103-B(4):644-649.

Biomechanical Behavior of an Hydroxyapatite-Coated Traditional Hip Stem and a Short One of Similar Design: Comparative Study Using Finite Element Analysis

Background

The objective is to compare, by the means of finite elements analysis, the biomechanical behavior of a conventional stem of proven performance with a short stem based on the same fixation principles.

Methods

A 3D femur was modeled from CT scan data, and real bone density measures were incorporated into it. Load stresses were applied to that bone in 3 different scenarios: without prosthesis, with the conventional stem, and with the short stem. Different bone loading patterns were compared by Gruen’s zones both visually and statistically using Welch’s test.

Results

The implantation of a stem generates a certain degree of stress shielding in the surrounding bone, but the pattern of the change is very similar in the compared stem models. Although there is statistical significance (P < 0.01) in the mean stress variation in most of the Gruen’s zones, the magnitude of the difference is always under 2 MPa (range: 0.01 – 1.74 MPa).

Conclusions

The bone loading patterns of the traditional stem and the short stem are very similar. Although there is no evidence of a link between biomechanics and clinical outcomes, our results may suggest that theoretical advantages of short stems can be exploited without the fear of altering bone loading patterns.

The impact of reducing the femoral stem length in total hip arthroplasty during gait

AIM

The length of the femoral stem in total hip arthroplasty (THA) is a practical consideration to prevent gait impairment. The aim of this study was to determine if reducing the femoral stem length in THA would lead to impaired gait biomechanics.

METHODS

Patients uniformly with the same brand implant of differing lengths (100 mm vs 140-166 mm) were taken retrospectively from a prospective trial introducing a new short stem. Twelve patients without any other disorder to alter gait besides contralateral differing length stem THA were tested at differing gradients and speed on a validated instrumented treadmill measuring ground reaction forces. An anthropometrically similar group of healthy controls were analysed to compare.

RESULTS

With the same posterior surgical approach, the offset and length of both hips were reconstructed within 5 mm of each other with an identical mean head size of 36 mm. The short stem was the last procedure for all the hips with gait analysis occurring at a mean of 31 and 79 months postoperatively for the short and long stem THA, respectively. Gait analysis between limbs of both stem lengths demonstrated no statistical difference during any walking condition. In the 90 gait assessments with three loading variables, the short stem was the favoured side 51% of the time compared 49% for the long stem.

CONCLUSION

By testing a range of practical walking activities, no lower limb loading differences can be observed by reducing the femoral stem length. A shorter stem demonstrates equivalence in preference during gait when compared to a reputable conventional stem in total hip arthroplasty.

Ultraviolet irradiation improves the hydrophilicity and osteo-conduction of hydroxyapatite

Background

Treating a titanium or titanium alloy implant with ultraviolet (UV) light is known to improve its associated cell growth and osseointegration. However, little is known about the effect of UV irradiation on hydroxyapatite (HA), which is also used frequently in orthopaedic and dental surgery. Here we examined the effect of UV irradiation on the hydrophilicity of HA, and on its osteoconduction ability in rats.

Methods

HA implants of low and high porosity were treated with UV light, and photofunctionalisation was assessed by the contact angle of a water drop on the surface. HA implants were also inserted into rat femurs, and the rats were killed 2 or 4 weeks later. The bone volume and bone area ratio were calculated from microcomputed tomography and histological data.

Results

The contact angle of a water drop on HA implants of both porosities was significantly reduced after UV irradiation. In the rat femurs, there was no significant difference in the bone volume between the UV light-treated and control implants at 2 or 4 weeks. The bone area ratio for the UV light-treated versus control implants was significantly increased at 2 weeks, but there was no significant difference at 4 weeks.

Conclusions

The surface of UV-irradiated HA disks was hydrophilic, in contrast to that of non-irradiated HA disks. Photofunctionalisation accelerated the increase in the bone area ratio in the early healing stage. This technology can be applied to surgical cases requiring the early fusion of bone and HA.

Cementless jumbo cups for revision of failed Furlong prosthesis. A case series

BACKGROUND

Revision of failed total hip arthroplasty (THA) presents great challenge to any orthopaedic surgeon especially in the presence of acetabular defects where the main goal is to achieve durable fixation of prosthetic components to bone which is the key to successful revision surgery.

METHODS

Seventeen patients (17 hips) with mean age of 52 (40-61) years had revision surgery for aseptic failure of Furlong hydroxyapatite-ceramic-coated (HAC) prosthesis using cementless jumbo cups. Patients were reviewed clinically and radiographically with mean follow-up of 3.5 years (2-6). No patient was lost to follow up.

RESULTS

All revised acetabular components showed polyethylene wear, severe metallosis, with acetabular defects IIB (4/17), and IIIA (13/17) according to Paprosky classification. The femoral component was well fixed in all cases but one patient had stem revision for femoral fracture mal-union. There was one early post-operative infection; there was no postoperative dislocation, sciatic nerve injury, periprosthetic fracture or deep venous thrombosis. At last follow-up, no progressive radiolucencies or acetabular migration was identified. The mean Harris hip score improved from 42 (24-59) pre-operatively to 85 (72-92).

CONCLUSION

Good clinical results and radiographic stability were obtained at short term follow up after acetabular revision using cementless jumbo cups, which justify its use in revision surgery even in the face of major acetabular defects. Furlong HAC femoral component gives excellent long-term survival in young and active patients with a survival rate of 94% at 18.6 years.

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

Aims

We previously reported the long-term results of the cementless Duraloc-Profile total hip arthroplasty (THA) system in a 12- to 15-year follow-up study. In this paper, we provide an update on the clinical and radiological results of a previously reported cohort of patients at 23 to 26 years´ follow-up.

Patients and Methods

Of the 99 original patients (111 hips), 73 patients (82 hips) with a mean age of 56.8 years (21 to 70) were available for clinical and radiological study at a minimum follow-up of 23 years. There were 40 female patients (44 hips) and 33 male patients (38 hips).

Results

All acetabular and femoral components were well fixed and showed signs of bone ingrowth. Nine acetabular components were revised due to wear-osteolysis-related problems and four due to late dislocation. The probability of not having component revision at 25 years was 83.2% (95% confidence interval (CI) 74.5 to 91.8; number at risk 41). Acetabular osteolysis was observed in ten hips. The mean femoral head penetration was 1.52 mm (sd 0.8) at 15 years and 1.92 mm (sd 1.2) at 25 years. Receiver operating characteristic (ROC) analysis revealed that mean femoral penetration with a value of 0.11 mm/year or more was associated with the appearance of osteolysis. The 25-year Kaplan–Meier survival with different endpoints was 89.9% for acetabular osteolysis (95% CI 83.3 to 96.5), 92.1% for proximal femoral osteolysis (95% CI 86.1 to 98.2), and 75.5% for femoral osteopenia (95% CI 66.5 to 84.5).

Conclusion

The Duraloc-Profile THA system showed excellent long-term bone fixation. Nevertheless, monitoring is recommended in order to detect wear and late dislocations in this population that was relatively young at the time of surgery. Cite this article: Bone Joint J 2019;101-B:378–385.

Primary stability of a short bone-conserving femoral stem

Aims

The aim of this study was to determine the stability of a new short femoral stem compared with a conventional femoral stem in patients undergoing cementless total hip arthroplasty (THA), in a prospective randomized controlled trial using radiostereometric analysis (RSA).

Patients and Methods

A total of 53 patients were randomized to receive cementless THA with either a short femoral stem (MiniHip, 26 patients, mean age: 52 years, nine male) or a conventional length femoral stem (MetaFix, 23 patients, mean age: 53 years, 11 male). All patients received the same cementless acetabular component. Two-year follow-up was available on 38 patients. Stability was assessed through migration and dynamically inducible micromotion. Radiographs for RSA were taken postoperatively and at three, six, 12, 18, and 24 months.

Results

At two years, there was significantly less subsidence (inferior migration) of the short femoral stem (head, 0.26 mm, 95% confidence interval (CI) 0.08 to 0.43, sd 0.38; tip, 0.11 mm, 95% CI -0.08 to 0.31, sd 0.42) compared with the conventional stem (head, 0.62 mm, 95% CI 0.34 to 0.90, sd 0.56, p = 0.02; tip, 0.43 mm, 95% CI 0.21 to 0.65, sd 0.44, p = 0.03). There was no significant difference in dynamically inducible micromotion, rate of complications or functional outcome.

Conclusion

This study demonstrates that the short femoral stem has a stable and predictable migration. However, longer-term survival analysis still needs to be determined. Cite this article: Bone Joint J 2018;100-B:1148–56.

3rd generation ceramic-on-ceramic cementless total hip arthroplasty: a minimum 10-year follow-up study

INTRODUCTION

3^rd generation ceramic bearings were introduced in total hip arthroplasty (THA) with the potential to have better mechanical strength and wear properties than their predecessors. At present, there are few studies looking at the long-term results of this latest generation of ceramic bearings. The purpose of our study was to investigate the long-term clinical and radiographic results of 3^rd generation ceramic-on-ceramic THA and the incidence of ceramic specific complications such as squeaking and bearing surface fracture.

METHODS

The database of the senior author (J.D.W.) was reviewed. A total of 126 hip replacements performed in 108 patients (average age 39.6 years) with an average follow-up of 12.1 years (10-16 years) was identified. Clinical notes and plain radiographs were reviewed. To measure function, patients were contacted and an Oxford Hip Questionnaire was completed. Patients were also directly questioned about the presence of squeaking or any other sounds from the hip. Radiographs were evaluated for signs of wear, osteolysis, loosening and heterotopic ossification. The abduction angle of the acetabular component was measured.

RESULTS

The average Oxford Hip Score was 39.8 out of 48. Survivorship at 10 years was 94.6% (95% CI) with revision for any cause as the endpoint. There was 1 femoral head fracture, no osteolysis, no squeaking and no detectable wear.

CONCLUSIONS

The good clinical and radiographic results for this series of patients are similar to other recent long-term studies looking at 3^rd generation ceramic-on-ceramic THA. The results compare favourably with other bearing surfaces. The lack of osteolysis associated with this articulation is encouraging and may also make it a good choice for younger patients requiring total hip replacement.

Does hydroxyapatite coating enhance ingrowth and improve longevity of a Zweymuller type stem? A double-blinded randomised RSA trial

INTRODUCTION

An ongoing discussion is whether using a hydroxyapatite coating enhances the ingrowth and longevity of a femoral stem in total hip arthroplasty. The best way to predict speed of ingrowth and long-term outcome is by evaluating micromotion by radiostereometric analysis. To study the effect of hydroxyapatite (HA) coating on the migration of the SL-PLUS hip stem, we performed a prospective double blind randomised controlled trial comparing the early migration of the hydroxyapatite (HA)-coated SL-PLUS stem compared to the Standard (non-coated) SL-PLUS stem.

PATIENTS AND METHODS

51 patients were randomly assigned to receive either an uncoated or a HA-coated femoral component during total hip replacement. RSA images were obtained direct postoperatively and at 6 weeks, 12 weeks, 6 months, 12 months and 24 months. HOOS scores were obtained preoperative and at final follow-up.

RESULTS

RSA evaluation demonstrated significant migration up to 3 months postoperatively in both groups. After initial setting no significant migration was observed. There was no significant difference in migration between the HA-coated group and the uncoated group. Both Harris Hip Score (HHS) and HOOS domain scores (pain and ADL) significantly improved compared to baseline at 24 months after surgery in both treatment groups (p<0.001 for all comparisons). Improvement did not differ significantly between the 2 groups.

CONCLUSIONS

At 2 years follow-up, the HA-coated and uncoated Zweymuller type, distal fitting stem do not show different migration patterns.

Total Hip Arthroplasty with Use of the Cementless Zweymüller Alloclassic System: A Concise Follow-up, at a Minimum of 25 Years, of a Previous Report

We previously reported the 10 to 13-year follow-up results for 104 total hip replacements with the Zweymüller Alloclassic stem and a threaded cup in 94 patients. The present study is a clinical and radiographic outcome update after a minimum follow-up of 25 years. Four patients (4 hips) were lost and 46 patients (50 hips) died, leaving 44 patients (50 hips) available for follow-up. Since our previous report, 7 cups and 2 stems were revised. At 20 years, the probability of survival of any component was 84.1% (95% confidence interval [CI], 73.91% to 94.29%) and the cumulative probability of not having stem loosening was 95.9% (95% CI, 95.51% to 96.29%). We observed proximal femoral osteolysis in 15 hips (30%), cortical hypertrophy in 21 hips (42%), and proximal femoral osteopenia in 30 hips (60%). The Zweymüller Alloclassic stem continues to provide excellent results after extended follow-up.

LEVEL OF EVIDENCE

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

3rd generation ceramic-on-ceramic cementless total hip arthroplasty: a minimum 10-year follow-up study

INTRODUCTION

3rd generation ceramic bearings were introduced in total hip arthroplasty (THA) with the potential to have better mechanical strength and wear properties than their predecessors. At present, there are few studies looking at the long-term results of this latest generation of ceramic bearings.The purpose of our study was to investigate the long-term clinical and radiographic results of 3rd generation ceramic-on-ceramic THA and the incidence of ceramic specific complications such as squeaking and bearing surface fracture.

METHODS

The database of the senior author (J.D.W.) was reviewed. A total of 126 hip replacements performed in 108 patients (average age 39.6 years) with an average follow-up of 12.1 years (10-16 years) was identified. Clinical notes and plain radiographs were reviewed. To measure function, patients were contacted and an Oxford Hip Questionnaire was completed. Patients were also directly questioned about the presence of squeaking or any other sounds from the hip. Radiographs were evaluated for signs of wear, osteolysis, loosening and heterotopic ossification. The abduction angle of the acetabular component was measured.

RESULTS

The average Oxford Hip Score was 39.8 out of 48. Survivorship at 10 years was 94.6% (95% CI) with revision for any cause as the endpoint. There was 1 femoral head fracture, no osteolysis, no squeaking and no detectable wear.

CONCLUSIONS

The good clinical and radiographic results for this series of patients are similar to other recent long-term studies looking at 3rd generation ceramic-on-ceramic THA. The results compare favourably with other bearing surfaces. The lack of osteolysis associated with this articulation is encouraging and may also make it a good choice for younger patients requiring total hip replacement.

Displaced intracapsular neck of femur fractures: Outcome of 810 hydroxyapetite coated (HAC) uncemented hemiarthroplasties

A Cochrane review influenced new NICE guidelines, which recommended surgeons: Offer cemented implants to patients undergoing surgery with arthroplasty. However our trust routinely uses HAC uncemented stem (Taperloc^®, Biomet) hemiarthroplasties. A review of a consecutive series of uncemented HAC stem hemiarthroplasties including measures such as intro-operative complications, mortality and revision surgery. Prospectively collected data between January 2008 and June 2014 was used, with medical record and radiographic reviews performed. 810 consecutive Taperloc uncemented hemiarthroplasty with monopolar heads were performed in 763 patients, with a minimum 12 month follow-up (12-90) follow-up. Mean age 83yrs; 71% female. Meantime to operation was 28.5h. 30day mortality: 4.4% (33/763). One year mortality was 11.2% (89/763). 2.5% (20/810) were admitted on a separate admission with the periprosthetic fracture. 0.6% (5/810) were revised to total hip replacement for subsidence and associated pain. Only 1% (8/810) had intraoperative calcar fractures, all of which were treated with intraoperative cabling with no evidence of clinically relevant subsidence or medium term complications requiring revision surgery within a year. To the author's knowledge this is largest outcome series for modern design uncemented hemiarthroplasty. Our study shows comparable data to cemented hemiarthroplasty but no deaths in the first 2days post-op. Our series also demonstrates a well below average mortality figures which are clearly multifactorial but believe uncemented prosthesis play a role. We believe that uncemented proven stem design hemiarthroplasty remains a safe and good surgical option for displaced intracapsular fractures.

Survival of hydroxyapatite-coated cups: acetabular screws involve a lower rate of revision surgery due to aseptic loosening

BACKGROUND

It is believed that the path of acetabular screws may represent a shuttle between hydroxyapatite (HA) particles and the liner. The aim was to assess the relationship between acetabular screws and revision surgery for aseptic loosening in total hip arthroplasties (THAs).

MATERIAL AND METHODS

A retrospective multicentric study was performed. Patients older than 18 years and patients who underwent THA with both the stem and cup HA-coated were included. The rate of revision-surgery considering only aseptic loosening was calculated. The proportion of cases in which acetabular screws were used was registered, as well as the proportion of cups that showed osteolysis. The statistical relationship between acetabular screws and osteolysis, as well as acetabular screws and revision-surgery for aseptic loosening were assessed.

RESULTS

There were 749 cases. Mean age 62.1 (45-84) years. Mean follow-up 14.19 (8.9-16.7) years. Revision surgery was performed in 12.8% (96/749) of the cups. 73.95% (71/96) of the revised cups showed aseptic loosening. The overall 15-year survival of the cups considering only aseptic loosening was 84.4%. Acetabular screws were used in 47.5% (356/749) of the cups. Acetabular screws were used in 40.44% (55/136) of the cups that showed osteolysis. The use of acetabular screws was associated with less osteolysis (p = 0.006). Acetabular screws were used in 35.21% (25/71) of the cups that were revised for aseptic loosening. The use of acetabular screws was associated with a lower rate of revision surgery (p = 0.020).

CONCLUSIONS

In THA with the stem and cup HA-coated, the use of acetabular screws is associated with a lower rate of revision surgery.

Ultrashort versus Conventional Anatomic Cementless Femoral Stems in the Same Patients Younger Than 55 Years

BACKGROUND

Because the clinical and radiographic performance of an ultrashort anatomic cementless stem has been investigated in only two randomized controlled studies, well-designed trials should aim for a thorough comparison of the outcomes of ultrashort anatomic cementless and conventional anatomic cementless stems.

QUESTIONS/PURPOSES

The purposes of this study were to compare (1) the clinical results, including Harris hip score, thigh pain, and WOMAC index score, (2) radiographic results, (3) bone mineral density; and (4) proportions of patients undergoing revision of a THA using an ultrashort anatomic cementless stem versus a conventional anatomic cementless stem in the same patients who underwent bilateral sequential THAs under the same anesthetic.

METHODS

Two hundred patients (mean age, 53 years; range, 26-54 years) who underwent bilateral sequential THAs received an ultrashort anatomic cementless stem in one hip and a conventional anatomic cementless stem in the contralateral hip. From January 2004 to December 2005, we performed 524 same-day bilateral short and conventional anatomic cementless THAs in 262 patients, of whom 212 (81%) participated in this study. Five patients were lost to followup before 2 years, five were lost between 2 to 10 years, and two were lost between 10 to 13 years, leaving 200 patients. Patients who had end-stage bilateral hip disease and were younger than 55 years were selected for inclusion. The predominant diagnoses were osteonecrosis (118 patients, 59%) and osteoarthritis (44 patients, 22%). One hundred thirty-eight were men and 62 were women. At the time of each followup, the patients were assessed clinically and radiographically. In addition, each patient completed the WOMAC and the University of California Los Angeles (UCLA) activity scores. The minimum followup was 10 years (mean, 11.8 years; range, 10-13 years). Followups were done in person, with all images and followup clinic notes. Based on the power analysis, we estimated a sample size of 178 hips was needed in each group to detect a 3-point difference in the Harris hip score with 80% power.

RESULTS

At the latest followup, there were no differences between the two groups regarding the mean Harris hip scores (94 versus 94 points; p = 0.189), mean WOMAC scores (17 versus 16 points; p = 0.191), or mean UCLA activity scores (9 versus 9 points; p = 0.381). Two patients in the ultrashort stem group and one patient in the conventional stem group had severe (9 points) thigh pain, and 30 patients (15%) in the conventional stem group had mild thigh pain (2 or 3 points) after vigorous exercise. Bone mineral density in the ultrashort and conventional stem groups, respectively, was greater in the ultrashort stem group than in the conventional stem group. Bone mineral density in Zone 1 at 12 years was 3.29 versus 1.88 g/cm(2) (p = 0.021), and 2.97 versus 0.91 g/m(2) in Zone 7 (p = 0.001). With the numbers available, there were no differences between the stem designs in terms of the proportion undergoing revision (one hip, 0.5%, in the short-stem group versus one hip, 0.5%, in the conventional group; p = 1.881).

CONCLUSIONS

At followup into the second decade, ultrashort stems showed no differences from conventional cementless stems in terms of validated outcomes scores or fixation, although less stress shielding was observed. Reduction of stress shielding may reduce the long-term risk of periprosthetic fracture, but this was not shown in our study.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Radiological identification of Zweymüller-type femoral stem prosthesis in revision cases

INTRODUCTION

Since 1979 the number of patients treated with femoral stems has continued to grow, as well as the number of stems with features similar to the Zweymüller prosthesis produced by different companies. Identification can be problematic in case requiring revision. In the present paper, we present an overview of morphometric differences between the different stem designs, which can be useful for radiologic identification in revision cases.

METHODS

By doing some research on the Internet of specialized sites and worldwide literature, we searched for all femoral stems agreeing with Zweymüller principles (cementless, straight, tapered, rectangular cross-sectioned femoral stems).

RESULTS

We found 26 different stems from different companies producing or having produced in the past the Zweymüller-type femoral stems for hip prosthesis.

DISCUSSION

Accurate preoperative identification of the Zweymüller femoral stem type may be of critical importance to eventual outcomes following revision surgery. Each manufacturer has different instruments specific to the removal of their primary implants, and ensuring they are available can simplify the revision procedure significantly. Exact pre-operative planning is also necessary for selecting the correct ball head in cases where a stem is well-fixed and can be left in situ. The commonly used notation "Eurocone 12/14" provides no information about the actual taper angle. Whenever the stem is left in situ, the exact specifications of the taper must therefore be obtained from the manufacturer in order to use a metal sleeve that precisely fits it and the ball head. Failure to do so may result in severe complications, such as metallosis. In cases where it is not possible to identify the taper angle, the surgeon may even consider removal of the stem, though this significantly increases the surgical procedure's invasiveness. Only a single, uniform standard taper, such as that offered until 1994 by CeramTec, can solve these issues in the future.

CONCLUSION

The survival rate of the Zweymüller stems after ten years was 96 % and the complication rate was very low. Pre-operative identification of the femoral implant is of considerable importance for planning and correctly implementing revision procedures.

Personal Perspectives on Enablers and Barriers to Accessing Care for Hip and Knee Osteoarthritis

BACKGROUND

Despite increasing demand for joint replacement surgery and other health services for hip and knee osteoarthritis (OA), barriers and enablers to individual access to care are not well understood. A comprehensive understanding of drivers at all levels is needed to inform efforts for improving access.

OBJECTIVE

The aim of this study was to explore perceived barriers and enablers to receiving conservative (nonsurgical) and surgical treatment for hip and knee OA.

DESIGN

This was a qualitative study using directed content analysis.

METHODS

Semistructured telephone interviews were conducted, with 33 participants randomly sampled from an Australian population-based survey of hip and knee OA. Each interview covered factors contributing to receiving treatment for OA and perceived barriers to accessing care. Interview transcripts were coded and organized into themes.

RESULTS

Key barriers to accessing care for OA included medical opinions about saving surgery for later and the appropriate age for joint replacement. Other common barriers included difficulty obtaining referrals or appointments, long waiting times, work-related issues, and limited availability of primary and specialist care in some areas. Several participants perceived a lack of effective treatment for OA. Private health insurance was the most frequently cited enabler and was perceived to support the costs of surgical and conservative treatments, including physical therapy, while facilitating faster access to surgery. Close proximity to services and assistance from medical professionals in arranging care also were considered enablers.

CONCLUSIONS

People with hip or knee OA experience substantial challenges in accessing treatment, and these challenges relate predominantly to health professionals, health systems, and financial factors. Private health insurance was the strongest perceived enabler to accessing care for OA.

Hydroxyapatite ceramic-coated femoral components in young patients followed up for 17 to 25 years: an update of a previous report

This study reports the results of 38 total hip arthroplasties (THAs) in 33 patients aged < 50 years, using the JRI Furlong hydroxyapatite ceramic (HAC)-coated femoral component. This represents an update of previous reports of the same cohort at ten and 16 years, which were reported in 2004 and 2009, respectively. We describe the survival, radiological and functional outcomes at a mean follow-up of 21 years (17 to 25). Of the surviving 34 THAs, one underwent femoral revision for peri-prosthetic fracture after 21 years, and one patient (one hip) was lost to follow-up. Using aseptic loosening as the end-point, 12 hips (31.5%) needed acetabular revision but none needed femoral revision, demonstrating 100% survival (95% confidence interval 89 to 100). In young patients with high demands, the Furlong HAC-coated femoral component gives excellent long-term results.

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

Since various interactions among cells, surrounding tissues and implanted biomaterials always occur at their interfaces, the surface properties of potential implants appear to be of paramount importance for the clinical success. In view of the fact that a limited amount of materials appear to be tolerated by living organisms, a special discipline called surface engineering was developed to initiate the desirable changes to the exterior properties of various materials but still maintaining their useful bulk performances. In 1975, this approach resulted in the introduction of a special class of artificial bone grafts, composed of various mechanically stable (consequently, suitable for load bearing applications) implantable biomaterials and/or bio-devices covered by calcium orthophosphates (CaPO4) to both improve biocompatibility and provide an adequate bonding to the adjacent bones. Over 5000 publications on this topic were published since then. Therefore, a thorough analysis of the available literature has been performed and about 50 (this number is doubled, if all possible modifications are counted) deposition techniques of CaPO4 have been revealed, systematized and described. These CaPO4 deposits (coatings, films and layers) used to improve the surface properties of various types of artificial implants are the topic of this review.

Cementless hydroxyapatite coated hip prostheses

More than twenty years ago, hydroxyapatite (HA), calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality.

Design modifications of the uncemented Furlong hip stem result in minor early subsidence but do not affect further stability: a randomized controlled RSA study with 5-year follow-up

BACKGROUND AND PURPOSE

Even small design modifications of uncemented hip stems may alter the postoperative 3-D migration pattern. The Furlong Active is an uncemented femoral stem which, in terms of design, is based on its precursor-the well-proven Furlong HAC-but has undergone several design changes. The collar has been removed on the Active stem along with the lateral fin; it is shorter and has more rounded edges in the proximal part. We compared the migration patterns of the uncemented Furlong HAC stem and the modified Furlong Active stem in a randomized, controlled trial over 5 years using radiostereometry (RSA).

PATIENTS AND METHODS

50 patients with primary osteoarthritis were randomized to receive either the HAC stem or the Active stem. The patients underwent repeated RSA examinations (postoperatively, at 3 months, and after 1, 2, and 5 years) and conventional radiography, and they also filled out hip-specific questionnaires.

RESULTS

During the first 3 months, the collarless Active stem subsided to a greater extent than the collar-fitted HAC stem (0.99 mm vs. 0.31 mm, p=0.05). There were, however, no other differences in movement measured by RSA or in clinical outcome between the 2 stems. After 3 months, both stem types had stabilized and almost no further migration was seen.

INTERPRETATION

The Active stem showed no signs of unfavorable migration. Our results suggest that the osseointegration is not compromised by the new design features.

Effect of hydroxyapatite coating on the radio-clinical results of a grit-blasted titanium alloy femoral taper. A case-control study of 198 cementless primary total hip arthroplasty with the Alloclassic™ system

BACKGROUND

The effect of hydroxyapatite (HA) coating on the fixation of a cementless femoral stem is discussed, in particular in cases of primary fixation with geometrically stable components. Therefore, we performed a comparative retrospective study of a series of Alloclassic-SL™ stems to: 1) present the long-term results and 2) evaluate the contribution, if any, of proximal HA coating.

HYPOTHESES

Long-term cementless press-fit ("flat wedge-shaped") fixation is reliable and HA coating only improves the radiological results of the proximal bone-prosthesis interface.

MATERIALS AND METHODS

One hundred and ninety-eight Alloclassic total hip arthroplasties were performed in 179 patients, mean age 66 years old (22-85), including 105 with proximal HA coating and 93 with the original grit-blast coating. One hundred and ninety-three hips were analyzed after a mean follow-up of 9.8 years (1-24 years).

RESULTS

Results were excellent or good in 184 hips (95%) with no significant difference between the 2 groups (Merle d'Aubigné≥16 for 89/92 (98%) without HA compared to 95/101 (94%) with HA P=0.59). Radiographic signs of stable osseointegration were observed in 173 hips (90% of the cases). HA coating significantly improved the radiographic results of the proximal bone-implant interface: (42/92 (46%) of the stems without HA had proximal radiolucencies in zones 1 and 7 compared to 4/101 (4%) with HA (P=0.0001)). Polyethylene wear>0.1 mm/year was observed in 6 hips (3%) including 1/101 (1%) in the group with HA versus 5/92 (5.4%) without HA (P=0.17). One intra-operative femoral fracture occurred and there were 9 dislocations in the first 3 postoperative months (4.5%). The main cause of revision surgery was recurrent dislocation (11/17 cases). The "revision per-100 observed-femoral component years" was 0.10 in both groups and survival for aseptic loosening of the stem was 100% (95% CI=73.2% to 100%) at 20 years.

CONCLUSION

This study shows that secondary fixation by osseointegration of a straight standard grit-blasted titanium alloy non-anatomical implant is reliable. Possible proximal fibrous encapsulation, which is reduced by HA coating, but especially conventional polyethylene wear, were the main limitations of this system.

LEVEL OF EVIDENCE

III retrospective case-control study.

The Effect of Hydroxyapatite Coating on Long-term Results of Total Hip Arthroplasty with Hydroxyapatite-coated Anatomic Femoral Stem

Purpose

To evaluate the clinical and radiological results, as well as the survival rate, associated with total hip arthroplasty using a hydroxyapatite (HA)-coated anatomical femoral stem at a follow-up of ≥12 years.

Materials and Methods

From April 1992 to May 1997, 86 patients (102 hips) underwent total hip arthroplasty with a HA-coated ABG I (Anatomical Benoist Giraud; Howmedica) hip prosthesis. The average age at the time of surgery was 53.4 years and the mean duration of follow-up was 17.1 years (range, 12.1-21.0 years). The Harris hip score (HHS) and radiographic assessments of thigh pain were used to evaluate the clinical results. We observed osteointegration, cortical hypertrophy, reactive line, calcar resorption and osteolysis around the femoral stems. The survival rate of the femoral stems was evaluated by using the span of time to a revision operation for any reasons was defined as the end point.

Results

The mean HHS was 50.5 preoperatively and 84.2 at the time of last follow-up. Osteolysis only around the HA-coated proximal portion of the femoral stem was observed in 72 hips, cortical hypertrophy all around the distal portion of the femoral stem was observed in 38 hips, and calcar resorption was observed in 44 hips. A reactive line was observed in 13 hips, but was unrelated to component loosening. Stem revision operations were performed in 24 (23%) hips due to osteolysis (14 hips), fracture (5 hips) and infection (5 hips). The femoral stem survival rate was 75% over the mean duration of follow-up.

Conclusion

Total hip arthroplasty using a HA-coated anatomical femoral stem showed necessitated a high rate of revision operations due to osteolysis around the femoral stem in this long term follow-up study.

Long-term results using the straight tapered femoral cementless hip stem in total hip arthroplasty: a minimum of twenty-year follow-up

We report the first long-term results of a prospective cohort study after total hip arthroplasty using the cementless Bicontact hip stem. Between 1987 and 1990, 250 total hip arthroplasties in 236 patients were performed using the cementless Bicontact hip stem. The average follow-up was 22.8 years (20.4-24.8) and average age at index surgery was 58.1 years. Eighty-one patients died and 9 were lost to follow-up. We noted 11 stem revisions revealing an overall Kaplan Meier survival rate of 95.0% (CI 95%: 91.1-97.2%). The average Harris Hip Score revealed 81 points (range 24-93). The Bicontact hip stem demonstrated high survival rates despite high ages and osteopenic changes, which are equivalent to other long-term reports of cementless stem fixation.

Bioactive coatings for orthopaedic implants-recent trends in development of implant coatings

Joint replacement is a major orthopaedic procedure used to treat joint osteoarthritis. Aseptic loosening and infection are the two most significant causes of prosthetic implant failure. The ideal implant should be able to promote osteointegration, deter bacterial adhesion and minimize prosthetic infection. Recent developments in material science and cell biology have seen the development of new orthopaedic implant coatings to address these issues. Coatings consisting of bioceramics, extracellular matrix proteins, biological peptides or growth factors impart bioactivity and biocompatibility to the metallic surface of conventional orthopaedic prosthesis that promote bone ingrowth and differentiation of stem cells into osteoblasts leading to enhanced osteointegration of the implant. Furthermore, coatings such as silver, nitric oxide, antibiotics, antiseptics and antimicrobial peptides with anti-microbial properties have also been developed, which show promise in reducing bacterial adhesion and prosthetic infections. This review summarizes some of the recent developments in coatings for orthopaedic implants.

The S-ROM hydroxyapatite proximally-coated modular femoral stem in revision hip replacement

We report on 397 consecutive revision total hip replacements in 371 patients with a mean clinical and radiological follow-up of 12.9 years (10 to 17.7). The mean age at surgery was 69 years (37 to 93). A total of 28 patients (8%) underwent further revision, including 16 (4%) femoral components. In all 223 patients (56%, 233 hips) died without further revision and 20 patients (5%, 20 hips) were lost to follow-up. Of the remaining patients, 209 (221 hips) were available for clinical assessment and 194 (205 hips) for radiological review at mean follow-up of 12.9 years (10 to 17.7).

The mean Harris Hip Score improved from 58.7 (11 to 92) points to 80.7 (21 to 100) (p <  0.001) and the mean Merle d’Aubigné and Postel hip scores at final follow-up were 4.9 (2 to 6), 4.5 (2 to 6) and 4.3 (2 to 6), respectively for pain, mobility and function. Radiographs showed no lucencies around 186 (90.7%) femoral stems with stable bony ingrowth seen in 199 stems (97%). The survival of the S-ROM femoral stem at 15 years with revision for any reason as the endpoint was 90.5% (95% confidence interval (CI) 85.7 to 93.8) and with revision for aseptic loosening as the endpoint 99.3% (95% CI 97.2 to 99.8).

We have shown excellent long-term survivorship and good clinical outcome of a cementless hydroxyapatite proximally-coated modular femoral stem in revision hip surgery.

Cite this article: Bone Joint J 2014;96-B:730–6.

Enhanced osseous implant fixation with strontium-substituted bioactive glass coating

The use of endosseous implants is firmly established in skeletal reconstructive surgery, with rapid and permanent fixation of prostheses being a highly desirable feature. Implant coatings composed of hydroxyapatite (HA) have become the standard and have been used with some success in prolonging the time to revision surgery, but aseptic loosening remains a significant issue. The development of a new generation of more biologically active coatings is a promising approach for tackling this problem. Bioactive glasses are an ideal candidate material due to the osteostimulative properties of their dissolution products. However, to date, they have not been formulated with stability to devitrification or thermal expansion coefficients (TECs) that are suitable for stable coating onto metal implants while still retaining their bioactive properties. Here, we present a strontium-substituted bioactive glass (SrBG) implant coating which has been designed to encourage peri-implant bone formation and with a TEC similar to that of HA. The coating can be successfully applied to roughened Ti6Al4V and after implantation into the distal femur and proximal tibia of twenty-seven New Zealand White rabbits for 6, 12, or 24 weeks, it produced no adverse tissue reaction. The glass dissolved over a 6 week period, stimulating enhanced peri-implant bone formation compared with matched HA coated implants in the contralateral limb. Furthermore, superior mechanical fixation was evident in the SrBG group after 24 weeks of implantation. We propose that this coating has the potential to enhance implant fixation in a variety of orthopedic reconstructive surgery applications.

Nineteen year results of THA using modular 9 mm S-ROM femoral component in patients with small femoral canals

A retrospective analysis was undertaken of 30 consecutive THA performed in 25 patients with hypoplastic proximal femurs, who had received a 9-mm uncemented modular S-ROM stem. The mean patient age was 42 years (17-69 years), mean height was 152.5 cm (130-170.5 cm), mean weight was 63 kg (39-90 kg), and mean follow-up period was 19 years (range, 12-23 years). Subsidence was seen in 2 hips, with asymptomatic femoral osteolysis present in 11 hips; overall survival of the femoral stem was 93.3%, with two revisions of the femoral component required for aseptic loosening. After a mean follow-up of 19 years, the use of the S-ROM 9 mm femoral stem in the patient with the small femur was associated with a low revision rate due to aseptic loosening of the stem.

Minimum 10 year survivorship analysis of a partially coated hydroxyapatite tapered femoral stem in elderly patients with an average age over 75

This is a retrospective, non-comparative study of 212 consecutive patients who underwent Total Hip Arthroplasty with an uncemented hydroxyapatite (HA) coated stem system from November 1997 to March 2000. The objective of the study was to analyze the performance of the implant at a minimum of 10 years in older patients (mean age 79.6 years). The Kaplan-Meier survivorship of the femoral stem at 10 years was 100%, and 97.5% for the whole prosthesis. The mean Merle d'Aubigné clinical score improved from 4.4 ± 2.1 points pre-operatively to 13.39 ± 3.77 points at final follow-up (p<0.05), and the mean VAS score for thigh pain was 1.25. The radiographic analysis showed that there were no significant radiolucent lines or osteolysis compromising the fixation of the implant.

Long-term outcomes of a new model of anatomical hydroxyapatite-coated hip prosthesis

This prospective study was designed to evaluate 196 Anatomique Benoist Giraud (ABG II) total hip arthroplasties which were implanted between September 1999 and December 2000. A minimum 11 years follow up was completed in 183 cases. The bearing surfaces were polyethylene-zirconia in 84 cases, polyethylene-metal in 42 and ceramic-ceramic in 57. Changes in the femoral stem design, in relation to the previous ABG I model, have led to a significant improvement in stress-shielding. Polyethylene wear rate was lower by more than 50% compared with non-crosslinked polyethylene. Excellent and good results were obtained in 90.32% of cases, and implant survival was 98.39% at the end of follow-up.

Primary total hip replacement with a Furlong fully hydroxyapatite-coated titanium alloy femoral component

We present the extended follow-up (≥ 20 years) of a series of fully hydroxyapatite-coated femoral components used in 72 primary total hip replacements (THRs). Earlier results of this cohort have been previously published. All procedures were performed between 1986 and 1991. The series involved 45 women and 15 men with 12 bilateral procedures. Their mean age at the time of surgery was 60 years (46 to 80) and the mean duration of follow-up was 22.5 years (20 to 25). At final follow-up, the mean Merle d’Aubigné and Postel hip scores were 5.5 (4.5 to 6), 3.8 (3.5 to 5) and 3.3 (3.0 to 5.0) for pain, mobility and function, respectively. Of the patients 92% were very satisfied at the time of final follow-up.

There were seven revisions: six of the acetabular component for aseptic loosening and one of both the stem and the acetabular component for loosening due to deep infection. The survival of this prosthesis at 22.5 years with revision for any reason as the endpoint was 91.7% (95% confidence interval (CI) 84 to 99). Survival with aseptic loosening of the stem as the endpoint was 100% (95% CI 90 to 100).

This prosthesis provides pain relief in the long term. Survival of this component is comparable to the best results for primary THR with any means of fixation.

Cite this article: Bone Joint J 2013;95-B:467–71.

Thigh pain, subsidence and survival using a short cementless femoral stem with pure metaphyseal fixation at minimum 9-year follow-up

BACKGROUND

Short femoral stems designed to spare bone stock and improve load transfer at the proximal femur level have been introduced in recent years. However, little is known on the long-term outcomes of these stems.

HYPOTHESIS

Short cementless stems have low rate of thigh pain and subsidence as well as few revision needs at mid-term follow-up.

MATERIALS AND METHODS

We prospectively followed 64 patients (72 hips) undergoing total hip arthroplasty with a femoral stem designed to achieve a pure metaphyseal fixation. Patients with hip fracture, femoral neck deformity and osteoporotic bone were excluded. Clinical evaluations were performed annually until the last follow-up, a minimum of 9 years after surgery. At each follow-up, implant positioning was assessed on conventional plain films with a computer assisted radiographic evaluation.

RESULTS

The Harris hip score improved from 43 points (range 19-50) before surgery to 88 points (range 73-100) at the final follow-up (P=0.001), and the Womac score averaged 47 points (range 35-56 points) preoperatively and 76 points (range 63-84) at the last follow-up (P=0.001). Thigh pain was reported by five patients (8%) at the 2-year follow-up, but only in two (3%) was still present, and related to the prosthesis, at last follow-up. Computer assisted radiographic analysis showed a neutral alignment of the stem in 56% of cases, a varus-valgus alignment less than 5° in 36% and equal to 5° in 8%. Stem subsidence was observed in 12 hips but was less than 4mm in all cases (range 0-3mm). Calcar height remained unchanged over time. Adaptive bone remodelling, including proximal bone resorption and distal cortical hypertrophy were not observed at follow-up. No patients had aseptic loosening of the stem nor were radiolucent lines detectable at the level of the porous coating. Survivorship analysis showed a 100% survival rate of the stem at nine years.

DISCUSSION

This study showed that a femoral stem designed to achieve a pure metaphyseal fixation may obtain, in a selected group of patients with adequate bone quality, satisfactory clinical outcomes without compromising implant stability. The limited periprosthetic bone remodelling observed after a minimum of 9 years follow-up suggests that this type of implant may improve mechanical stresses on host bone compared with standard stems requiring diaphyseal fixation.

LEVEL OF EVIDENCE

Level IV. Historical series.

Calcium orthophosphate coatings, films and layers

In surgical disciplines, where bones have to be repaired, augmented or improved, bone substitutes are essential. Therefore, an interest has dramatically increased in application of synthetic bone grafts. As various interactions among cells, surrounding tissues and implanted biomaterials always occur at the interfaces, the surface properties of the implants are of the paramount importance in determining both the biological response to implants and the material response to the physiological conditions. Hence, a surface engineering is aimed to modify both the biomaterials, themselves, and biological responses through introducing desirable changes to the surface properties of the implants but still maintaining their bulk mechanical properties. To fulfill these requirements, a special class of artificial bone grafts has been introduced in 1976. It is composed of various mechanically stable (therefore, suitable for load bearing applications) biomaterials and/or bio-devices with calcium orthophosphate coatings, films and layers on their surfaces to both improve interactions with the surrounding tissues and provide an adequate bonding to bones. Many production techniques of calcium orthophosphate coatings, films and layers have been already invented and new promising techniques are continuously investigated. These specialized coatings, films and layers used to improve the surface properties of various types of artificial implants are the topic of this review.

Modern proximally tapered uncemented stems can be safely used in Dorr type C femoral bone

Cementless femoral fixation has become widely accepted in modern total hip arthroplasty. Treating patients who have a stovepipe-shaped femur (Dorr type C) with cementless implants has traditionally been challenging. We treated 53 consecutive patients (60 hips) who had type C bone with identical tapered, proximally coated implants and postoperative weight bearing as tolerated. At 6 weeks, all 60 hips had radiographically documented bony integration, and at 1 year, there was no evidence of fracture, subsidence, thigh pain, stress shielding, loose stems, or risk of failure. Of those patients, 40 (43 hips) had midterm follow-up (average, 6 years; range, 4-9 years); the findings were the same. We conclude that modern proximally tapered stems can be used with early weight bearing in patients with type C bone.

A concise minimum eight year follow-up of proximally porous-coated tapered titanium femoral stem in primary total hip arthroplasty

PURPOSE

Our goal was to assess clinical and radiographic outcomes using a second-generation circumferentially proximally porous-coated titanium alloy stem at a minimum of eight years of follow-up.

METHODS

Ninety-one hips (80 patients) with Fibre Metal Taper (FMT, Zimmer Inc, Warsaw, IN, USA) femoral stems implanted between May 1998 and April 2002 were followed prospectively and re-evaluated at a minimum of eight years postoperatively. The median patient age was 56 (range 34-78) years, with 40 women and 40 men. Radiographic data and clinical follow-up using Harris Hip Score (HHS) and EuroQol (EQ)-5D outcome measures were evaluated.

RESULTS

Mean follow-up was 9.61 (range 8-12.3) years. At the time of the most recent follow-up, the mean HHS was 85.8 (range 46-100) points, mean EQ-5D Weighted Health State Index was 0.76 (range 0.05-1.00), and mean EQ-5D Visual Analogue Score was 80 (range 24-100). All stems were biologically stable, with all hips having osseous ingrowth. One stem was revised due to early periprosthetic fracture with stem subsidence. No hip had diaphyseal osteolysis.

CONCLUSIONS

To our knowledge, the data presented here represent the longest clinical follow-up of this second-generation cementless, proximally porous-coated femoral stem. The stems were found to perform well clinically and radiographically beyond the first five years previously reported in the literature. Patients had high levels of satisfaction and function, and osseous fixation occurred reliably without evidence of distal osteolysis.

Early biological fixation of porous implant coated with paste-retaining recombinant bone morphogenetic protein 2

The aim of this study was to evaluate the period required for stable initial bone-implant fixation with recombinant human bone morphogenetic protein 2 (rhBMP-2) in the bone marrow of a rabbit model. The porous implants being coated with β-tricalcium phosphate/polylactide-polyethylene glycol paste with 15, 30, or 60 μg of rhBMP-2 (n = 10) were implanted into animals in 3 experimental groups. In 2 control groups, the test implants were coated without rhBMP or no paste. In all groups, the implant was inserted for 3 and 6 weeks. At 3 weeks after implantation, the BMP-treated implants in the 2 lower dose groups had significantly more bone ingrowth to the implant surface than did the control groups, and the greatest effect occurred in the 30-μg rhBMP-2 group animals.

The suitability of an uncemented hydroxyapatite coated (HAC) hip hemiarthroplasty stem for intra-capsular femoral neck fractures in osteoporotic elderly patients: the Metaphyseal-Diaphyseal Index, a solution to preventing intra-operative periprosthetic fracture

This study will seek to identify a measurable radiographic index, the Metaphyseal-Diaphyseal Index (MDI) score to determine whether intra-operative fracture in osteoporotic bone can be predicted.

A 5 year prospective cohort of 560 consecutive patients, undergoing hemiarthroplasty (cemented or uncemented), was evaluated. A nested case-control study to determine risk factors affecting intra-operative fracture was carried out.

The Vancouver Classification was used to classify periprosthetic fracture.

The MDI score was calculated using radiographs from the uncemented group. As a control (gold standard), Yeung et al's Canal Bone Ratio (CBR) score was also calculated. From this, a receiver operating characteristic (ROC) curve was formulated for both scores and area under the curve (AUC) compared. Intra and inter-observer correlations were determined.

Cost analysis was also worked out for adverse outcomes.

Four hundred and seven uncemented and one hundred and fifty-three cemented stems were implanted. The use of uncemented implants was the main risk factor for intra-operative periprosthetic fracture.

Sixty-two periprosthetic fractures occurred in the uncemented group (15.2%), nine occurred in the cemented group (5.9%), P < 0.001. The revision rate for sustaining a periprosthetic fracture (uncemented group) was 17.7%, P < 0.001 and 90 day mortality 19.7%, P < 0.03.

MDI's AUC was 0.985 compared to CBR's 0.948, P < 0.001. The MDI score cut-off to predict fracture was 21, sensitivity 98.3%, specificity 99.8%, positive predictive value 90.5% and negative predictive value 98%. Multivariate regression analysis ruled out any other confounding factors as being significant.

The intra and inter-observer Pearson correlation scores were r = 0.99, P < 0.001.

JRI uncemented hemiarthroplasty has a significantly higher intra-operative fracture rate. We recommend cemented arthroplasty for hip fractures. We propose a radiographic system that may allow surgeons to select patients who are good candidates for uncemented arthroplasty, but it needs prospective validation.

Hydroxyapatite-coated femoral stem/porous-coated acetabulum survivorship at 15 years

At 10 years, we reported survivorship of the Omnifit hydroxyapatite-coated femoral stem and the Omnifit-PSL porous-coated dual-radius acetabular shell (Stryker, Mahwah, NJ) with polyethylene liners sterilized by gamma radiation in air. Our 15-year follow-up examines survivorship and functional outcomes of this system. Ninety-two patients (98 hips) were identified from our database who had been involved with the prior study. The mean follow-up was 14.7 years (range, 11.8-17.0 years). Survival of the stem and cup was 98.8% and 69%, respectively. Osteolysis was seen in 56% of the proximal femur and 5% of the distal femur. This hydroxyapatite-coated stem continues to perform well at 15 years despite poor acetabular results. The performance of this acetabular component is consistent with previous literature.

Primary total hip arthroplasty with dual mobility socket to prevent dislocation: a 22-year follow-up of 240 hips

PURPOSE

The longest follow-up dual mobility series from inventor Gilles Bousquet focussing on implant survival and the incidence of dislocation.

METHODS

This was a retrospective study from 1985 to 1990, on 240 hips using a PF® modular femoral stem and a dual mobility Novae® tripodal socket (SERF).

RESULTS

The 22-year follow-up global survival rate was 74%. No dislocation occurred, 41 hips were revised, including ten retentive failures (RF), 12 hips were lost to follow-up, 87 patients (99 hips) died without revision, and 90 hips were still in situ.

CONCLUSION

The dual mobility socket global survival rate is comparable to similar series. The 0% dislocation rate demonstrates the success of dual mobility with regard to implant stability. The main issues were cup fixation, which might be improved by the use of macrostructures and HA coating, and osteolytic lesions, caused by polyethylene wear. Traditionally suitable for patients older than 60 years, dual mobility might be extended for use in patients over 50.