Uncemented femoral revision arthroplasty using a modular tapered, fluted titanium stem: 5- to 16-year results of 163 cases

Impact of fixation method on femoral bone loss: a retrospective evaluation of stem loosening in first-time revision total hip arthroplasty among two hundred and fifty five patients

PURPOSE

Implant loosening represent the most common indication for stem revision in hip revision arthroplasty. This study compares femoral bone loss and the risk of initial revisions between cemented and uncemented loosened primary stems, investigating the impact of fixation method at primary implantation on femoral bone defects.

METHODS

This retrospective study reviewed 255 patients who underwent their first revision for stem loosening from 2010 to 2022, receiving either cemented or uncemented stem implants. Femoral bone loss was preoperatively measured using the Paprosky classification through radiographic evaluations. Kaplan-Meier analysis estimated the survival probability of the original stem, and the hazard ratio assessed the relative risk of revision for uncemented versus cemented stems in the first postoperative year and the following two to ten years.

RESULTS

Cemented stems showed a higher prevalence of significant bone loss (type 3b and 4 defects: 32.39% vs. 2.72%, p < .001) compared to uncemented stems, which more commonly had type 1 and 2 defects (82.07% vs. 47.89%, p < .001). In our analysis of revision cases, primary uncemented stems demonstrated a 20% lower incidence of stem loosening in the first year post-implantation compared to cemented stems (HR 0.8; 95%-CI 0.3-2.0). However, the incidence in uncemented stems increased by 20% during the subsequent years two to ten (HR 1.2; 95%-CI 0.7-1.8). Septic loosening was more common in cemented stems (28.17% vs. 10.87% in uncemented stems, p = .001). Kaplan-Meier analysis indicated a modestly longer revision-free period for cemented stems within the first ten years post-implantation (p < .022).

CONCLUSION

During first-time revision, cemented stems show significantly larger femoral bone defects than uncemented stems. Septic stem loosening occurred 17.30% more in cemented stems.

Aseptic Revision Total Hip Arthroplasty Using Modular Fluted Tapered Stems: Long-Term Follow-up of 515 Cases

BACKGROUND

Modular fluted tapered (MFT) femoral components are frequently utilized in aseptic revision total hip arthroplasties (THAs). However, long-term follow-up has been limited. The purpose of this study was to update our prior series at long-term follow-up, with specific emphasis on implant survivorship, radiographic results, and complications in a large cohort of aseptic revision THAs using MFT stems.

METHODS

We retrospectively identified 515 aseptic femoral revisions performed with 2 MFT stem designs in the total joint registry of a single tertiary care academic institution from 1999 to 2013. Serial radiographs were reviewed for subsidence of >5 mm. The mean follow-up (and standard deviation) was 10 ± 5 years (range, 2 to 21 years). A competing risk model accounting for death was utilized.

RESULTS

The 15-year cumulative incidence of any revision was 12%. There were 57 revisions, 27 of which involved revision of the fluted tapered component (FTC). Dislocation (n = 19), periprosthetic joint infection (n = 15), and aseptic loosening of the FTC (n = 11) were the most common reasons for revision. The 15-year cumulative incidence of any reoperation was 16%. The 15-year cumulative incidences were 6% for any FTC revision and 2% for FTC revision for aseptic loosening. Stem subsidence of >5 mm occurred in 2% of unrevised cases, and all but 1 stem was stable at the most recent follow-up.

CONCLUSIONS

This large series of MFT stems used in aseptic revision THAs had a 2% incidence of subsequent revision of the FTC for aseptic loosening at 15 years. Dislocation and infection were the most common reasons for any revision.

LEVEL OF EVIDENCE

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

Long-term outcomes of revision total hip arthroplasty with the Zimmer Modular Revision hip system

Aims

There are limited long-term studies reporting on outcomes of the Zimmer Modular Revision (ZMR) stem, and concerns remain regarding failure. Our primary aim was to determine long-term survival free from all-cause revision and stem-related failure for this modular revision stem in revision total hip arthroplasty (THA). Secondary aims included evaluating radiological and functional outcomes.

Methods

We retrospectively identified all patients in our institutional database who underwent revision THA using the ZMR system from January 2000 to December 2007. We included 106 patients (108 hips) with a mean follow-up of 14.5 years (2.3 to 22.3). Mean patient age was 69.2 years (37.0 to 89.4), and 51.9% were female (n = 55). Indications for index revision included aseptic loosening (73.1%), infection (16.7%), fracture (9.3%), and stem fracture (0.9%). Kaplan-Meier analysis was used to determine the all-cause and stem-related failure revision-free survival. At most recent follow-up, Oxford Hip Scores (OHS) were collected, and radiological stem stability was determined using the Engh classification.

Results

A total of 17 hips (15.7%) underwent re-revision of any component. Indications for re-revision were stem failure (35.3%; n = 6), infection (29.4%; n = 5), instability (29.4%; n = 5), and acetabular aseptic loosening (5.9%; n = 1). The five- and 15-year all-cause survival was 89.7% (95% confidence interval (CI) 86.7 to 92.7) and 83.3% (95% CI 79.6 to 87.0), respectively. There were six re-revisions (5.6%) for stem failure; five for stem fracture and one for aseptic loosening. The five- and 15-year survival free from stem-related failure was 97.2% (95% CI 95.6 to 98.8) and 94.0% (95% CI 91.6 to 96.4), respectively. At final follow-up, the mean OHS was 36.9 (8.0 to 48.0) and 95.7% (n = 66) of surviving modular revision stems were well-fixed in available radiographs.

Conclusion

Femoral revision with the ZMR offers satisfactory long-term all-cause revision-free survival, good survival free of stem-related failure, and favourable clinical outcomes. Stem fracture was the most common reason for stem-related failure and occurred both early and late. This highlights the importance of both early and long-term surveillance for stem-related failure.

The Minimum 5-Year Follow up of a Highly Versatile Distally Anchored Femoral Revision System With Hydroxyapatite Coating

Background

Total hip arthroplasty is one of the most successful operations medicine can offer. As more patients undergo total hip arthroplasty the revision burden increases proportionately. This is a cohort study of the Arcos Modular Femoral Revision System.

Methods

The primary outcome was rerevision of the femoral component. Secondary outcomes include complications and radiological and clinical outcomes over 5 years.

Results

A total of 74 patients were recruited, and the femoral survival rate was 100% at 5 years with 12 censorships. A total of 31 patients were given Proprosky 3/4 preoperatively. Eleven patients underwent further procedures; however, no femoral components were revised. Kaplan-Meier analysis was performed by a biostatistician. Patients demonstrated a consistent and sustained improvement in Harris hip score, Oxford hip score, and EQ-5D. Radiological review revealed minimal and stable lysis around the femoral components.

Conculsion

The ARCOS Modular Femoral Revision System was designed to offer a range of options to allow femoral bone stock preservation and avoiding conversion to an endoprosthetic and seems to be effective in the medium term.

Retrospective survival analysis of the use of uncemented modular tapered stems for revision in periprosthetic Vancouver B-type fractures. Is instability a threat to survival?

INTRODUCTION AND OBJECTIVES

Periprosthetic hip fractures show increasing incidence and complexity, representing a challenge for the surgeon. We aimed to evaluate the survival of uncemented modular tapered stems in the treatment of periprosthetic Vancouver B2 and B3 type fractures and review the main complications and factors associated with decreased survival.

MATERIALS AND METHODS

We performed a retrospective study of patients submitted to revision arthroplasty for treatment of periprosthetic femoral stem Vancouver B2 and B3 type fractures with an uncemented modular fluted tapered stem (MRP-Titan). Demographic and radiographic parameters were analyzed. The survival rate (free of reoperation) was calculated at 2- and 5-years using the Kaplan-Meier survivorship analysis.

RESULTS

Thirty-nine patients were included with a mean age of 73.5 years and a mean follow-up of 5 years. Arthroplasty survivorship at 2 years was 73.7% and at 5 years was 67.5% (mean 8.4 years; range 6.7-10.2). Survivorship was inferior in the patients with episodes of instability (mean 2.5 years; range 0-5.42) (p<0.001). At least one episode of instability occurred in 26.3% of patients and 60% of these patients had a femoral head size 32mm or lower. At least one episode of instability occurred in 71.4% of patients with a greater trochanter fracture (p=0.008). The consolidation rate was 90.6% and the mortality rate was 23.7%. In the group of patients that died, 55.6% were submitted to at least one revision surgery (p=0.044).

CONCLUSION

Survivorship of an uncemented modular stem (MRP-Titan) in revision for PHF is significantly reduced by episodes of instability.

Femoral revision in total hip arthroplasty using a cementless modular stem: clinical and radiological results with a 8-year follow-up

INTRODUCTION

Modular femoral components allow for patient-specific restoration of hip joint geometry and the reconstruction of extensive bone defects in revision total hip arthroplasty (THA); however, potential problems of modular implants such as taper corrosion and the risk of implant fracture continue to be of concern. The aim of the present study was to evaluate the clinical and radiological results of a cementless modular revision stem following revision surgery due to aseptic loosening and periprosthetic fracture and to assess patient-reported outcome measures (PROMs) in these patients at mid-term follow-up.

MATERIALS AND METHODS

In this study, a consecutive cohort of 75 patients who underwent primary revision THA at our institution using a modular cementless stem design (MRP-TITAN stem) was retrospectively evaluated at a mean follow-up of 7.7 years. Kaplan-Meier survivorship analyses were performed with revision of the femoral component for any reason as the end point. The Harris-Hip Score, the UCLA Activity Score, the Forgotten Joint Score and the SF-12 Score were used for clinical assessment. We used the Wilcoxon signed rank test to compare pre- and postoperative clinical scores.

RESULTS

Overall stem survival with the endpoint stem re-revision for any reason was 85.4% at a mean follow-up of 7.7 years (range 2.4-14 years). Stem survival was 89.5% in the aseptic loosening group and 78.3% in the periprosthetic fracture group with no statistically significant difference between both groups (p = 0.107). One patient had to be revised due to taper fracture. PROMs improved significantly up to the latest follow-up, and radiographic evaluation showed full osseointegration of all stems in this cohort.

CONCLUSIONS

Revision THA using a modular cementless titanium revision stem demonstrated adequate clinical and radiological results at mid- to long-term follow-up in this cohort. Cementless revision stems are a useful treatment option to restore the anatomy, especially in deformed hips and in complex revision hip arthroplasty. However, there are some significant disadvantages related to an increased risk of mechanical failure such as corrosion/fretting damage and implant fracture. Future high-quality prospective studies with longer follow-up are necessary to confirm the supposed advantages.

Implant breakage and revision factors for modular fluted tapered stems in revision total hip arthroplasty

PURPOSE

Modular stems in revision total hip arthroplasties allow diaphyseal fixation and optimal restoration of the architecture of the proximal femur. Several studies report metaphyseal implant breakage having a negative impact on survivorship. The aim of the study was to evaluate the outcome of an uncemented modular fluted tapered stem (MFT) in revision surgery.

METHODS

In a retrospective study, 316 patients who had revision surgery using the same design of MFT implant (Modular Revision Stem [MRS], Lima Corporate, Italy) between 2012 and 2017 were identified. Patients were male in 51% of cases and mean age was 74 years. Indications were 110 periprosthetic fractures, 98 periprosthetic joint infection, 97 aseptic loosening, 10 instability and 1 other cause. Survivorship, complications, clinical and radiographic outcomes, were assessed. Mean follow-up was 5 years.

RESULTS

There was no implant breakage. At 5-year follow-up, the survivorship, free from revision for aseptic loosening and free of revision for any reason were 96% and 87%, respectively. At last follow-up (8 years), these figures were 92% and 71%, respectively. 31 implants were revised. The risk of revision for any cause was higher for extreme length metaphyseal implants, hazard ratio was 3.7 (95% CI, 1.82-7.52). A mean stem subsidence of 9 mm was noted in 37 cases; 4 were revised for aseptic loosening. The Harris Hip Score at final follow-up was 82.

CONCLUSIONS

At 5-year follow-up, the MFT implant showed a good survivorship and outcomes with no specific complications. Unlike literature reports, no specific complications occurred with this design. Stem junction positioning and therefore metaphyseal length may be key to optimise long-term survivorship. However, a longer follow-up is needed as implant breakage is more often seen after long implantation times.

Last generation fluted modular titanium stem in revision hip arthroplasty: a narrative review of mid- and long-term outcomes

Background and Objective

Tapered fluted titanium stems (TFTS), were introduced to overcome proximal femur bone defects. They obtain stable fixation even in catastrophic proximal bone loss. Modular ones have the advantage to adjust length, rotation, off-set independently from the distal module. Short-term publications have been showing favorable outcomes burdened by an unacceptably high rate of stem failure. Still, there is a paucity of mid- and long-term reports. This narrative review aims at analyzing recent literature on modular TFTS with at least 5 years of minimum follow-up to gain a better understanding of implant survival, performance, and complications.

Methods

A search of the PubMed database was performed with selected key terms. Results were screened after the application of strict inclusion and exclusion criteria. Extracted data were subsequently evaluated to obtain an up-to-date overview of the results and complications of TFTS.

Key Content and Findings

Modular TFTS showed a consistent increase in patient reported outcomes that persists at 10 years and above. Femoral fractures were the most common intraoperative complication. Despite modularity, dislocation still occurs at a variable rate (1.2-12%). With revision for any cause as an endpoint, overall survival approaches 83% after 10 years of follow-up. If femoral revision only is evaluated, excellent survival rates (>95%) have been published. Stem subsidence over 5 mm was reported in less than 5% of patients, only 1 requiring femoral revision. The mean incidence of stem mechanical failure was 3.39%, although most breakages occurred in stems eventually retired from the market.

Conclusions

Satisfactory survival rates were observed, with an acceptable rate of complications. Stem mechanical failure, excluding those stems eventually retired from the market, remains a marginal event. Therefore, the use of modular TFTS in revision surgery is safe and effective even in the long term.

Biomedical Applications of Titanium Alloys: A Comprehensive Review

Titanium alloys have emerged as the most successful metallic material to ever be applied in the field of biomedical engineering. This comprehensive review covers the history of titanium in medicine, the properties of titanium and its alloys, the production technologies used to produce biomedical implants, and the most common uses for titanium and its alloys, ranging from orthopedic implants to dental prosthetics and cardiovascular devices. At the core of this success lies the combination of machinability, mechanical strength, biocompatibility, and corrosion resistance. This unique combination of useful traits has positioned titanium alloys as an indispensable material for biomedical engineering applications, enabling safer, more durable, and more efficient treatments for patients affected by various kinds of pathologies. This review takes an in-depth journey into the inherent properties that define titanium alloys and which of them are advantageous for biomedical use. It explores their production techniques and the fabrication methodologies that are utilized to machine them into their final shape. The biomedical applications of titanium alloys are then categorized and described in detail, focusing on which specific advantages titanium alloys are present when compared to other materials. This review not only captures the current state of the art, but also explores the future possibilities and limitations of titanium alloys applied in the biomedical field.

Clinical and radiological outcomes and analysis of failures of modular revisions stems at long-term follow-up: a systematic review and meta-analysis

Background

Increasingly hip replacements at young age exposes the patient to an increased risk of failure of the implant over the years. In case of failure, revision specific stems were designed to overcome bone loss. Modularity of these devices is an important resource for the surgeon as they allow the new implant to be better adapted to the patient's anatomy. The purpose of this systematic review is to provide data about the outcome at long-term follow-up (>8 years) of hip modular revision femoral stems.

Methods

This systematic review and meta-analysis were conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement guidelines. PubMed and Google Scholar databases were systematically and independently searched, according to the inclusion and exclusion criteria. Two reviewers performed the data extraction independently. In case of disagreement, the senior authors were sought to resolve the divergences. Quality of the involved studies was evaluated with National Institute for Health and Care Excellence (NICE) guidelines (eight-item list) and the Newcastle-Ottawa scale (NOS). Primary and secondary outcomes were evaluated. The statistical analysis of this meta-analysis was performed by using Excel Microsoft and the software STATA.

Results

The primary outcome was the re-revision rate of modular revision stems at long-term follow-up. It ranged from 1.4% to 45.6%: random effect pooled estimate was 5.5% [95% confidence interval (CI): 4% to 7%], with a I2 of 12.3% (P=0.332). Mean Harris Hip Score (HHS) was 83 [min: 79; max: 87.6; standard deviation (SD): 3.55]. Secondary evaluated outcomes were: subsidence >5 mm, rate of periprosthetic infection or fractures (intra- and post-operative) and dislocations. The mean value for the NICE tool was 5.5 (SD: 1.13) and 7.3 (SD: 0.79) for the NOS tool. The survival rate was >90% at long-term follow-up (min: 60%; max: 97%).

Conclusions

The modular femoral revision stems have demonstrated good long-term reliability and efficacy. This meta-analysis demonstrates that the re-revision rate after 8 years of follow-up is low and 90% of the implants did not fail.

Prophylactic cable prevents tapered titanium stem subsidence with 2 cm of stem-cortical engagement in a cadaveric model

Aims

When performing revision total hip arthroplasty using diaphyseal-engaging titanium tapered stems (TTS), the recommended 3 to 4 cm of stem-cortical diaphyseal contact may not be available. In challenging cases such as these with only 2 cm of contact, can sufficient axial stability be achieved and what is the benefit of a prophylactic cable? This study sought to determine, first, whether a prophylactic cable allows for sufficient axial stability when the contact length is 2 cm, and second, if differing TTS taper angles (2° vs 3.5°) impact these results.

Methods

A biomechanical matched-pair cadaveric study was designed using six matched pairs of human fresh cadaveric femora prepared so that 2 cm of diaphyseal bone engaged with 2° (right femora) or 3.5° (left femora) TTS. Before impaction, three matched pairs received a single 100 lb-tensioned prophylactic beaded cable; the remaining three matched pairs received no cable adjuncts. Specimens underwent stepwise axial loading to 2600 N or until failure, defined as stem subsidence > 5 mm.

Results

All specimens without cable adjuncts (6/6 femora) failed during axial testing, while all specimens with a prophylactic cable (6/6) successfully resisted axial load, regardless of taper angle. In total, four of the failed specimens experienced proximal longitudinal fractures, three of which occurred with the higher 3.5° TTS. One fracture occurred in a 3.5° TTS with a prophylactic cable yet passed axial testing, subsiding < 5 mm. Among specimens with a prophylactic cable, the 3.5° TTS resulted in lower mean subsidence (0.5 mm (SD 0.8)) compared with the 2° TTS (2.4 mm (SD 1.8)).

Conclusion

A single prophylactic beaded cable dramatically improved initial axial stability when stem-cortex contact length was 2 cm. All implants failed secondary to fracture or subsidence > 5 mm when a prophylactic cable was not used. A higher taper angle appears to decrease the magnitude of subsidence but increased the fracture risk. The fracture risk was mitigated by the use of a prophylactic cable.

Longitudinal Radiographic Bone Density Measurement in Revision Hip Arthroplasty and Its Correlation with Clinical Outcome

The subjective analysis of conventional radiography represents the principal method for bone diagnostics in endoprosthetics. Alternative objective quantitative methods are described but not commonly used. Therefore, semi-quantitative methods are tested using digital computation and artificial intelligence to standardize, simplify, and ultimately improve the assessment. This study aimed to evaluate the correlation between relative density progressions and clinical outcomes. Radiographs and clinical examinations before and 24 and 48 weeks after surgery were obtained from sixty-eight patients with a modular hip stem. For the calculation of the relative bone density, the modal gray values of the Gruen zones were measured using ImageJ and were normalized by gray values of the highest and lowest ROI. The clinical outcomes were measured according to the Harris hip score before evaluating them for correlations. Analyses were performed separately for subgroups and bone regions. The Harris hip score increased from 44.15 ± 15.00 pre-operatively to 66.20 ± 13.87 at the latest follow-up. The relative bone density adjustment of Gruen zone 7 showed a significant correlation to its clinical outcome. Other bone adaptations could be realistically reproduced and differences by regional zones and patients' histories visualized. Next to the simplicity and that no additional examination is required, the method provides good semi-quantitative results and visualizes adaptations, which make it suitable for use.

Breakage of Tapered Junctions of Modular Stems in Revision Total Hip Arthroplasty—High Incidence in a Consecutive Series of a Single Institution

Background: Modularity in revision THA (RTHA) has become accepted during the last three decades. Nevertheless, specific risks of modularity of current revision devices such as breakage of taper junctions occur during follow-up. Data reporting failure rates are predominantly given by the manufacturers but independent data acquisition is missing so far. Questions/Purposes: 1. What time-related risk of breakage of taper junction between neck and body of an established modular revision device can be expected in a consecutive single institutional series and a mid-term follow-up? 2. Are there specific factors influencing breakage in this cohort? Materials and Methods: A retrospective analysis was performed of a consecutive series of 89 cases after femoral revision using a tapered modular revision stem. Mean follow-up period was 7.1 (range: 3.0–13.7) years. Breakage of stem as failure criteria of the implant was investigated with a Kaplan–Meier analysis. Results: Breakage of taper junctions occurred in four patients during follow-up showing a time-depending implant survival of 94.2 (95% CI: 88.6–100%) after 13.7 years. Implant survival of stems with lateralized necks of 87.4 (95% CI: 75.6–100%) after 13.7 years was significantly lower compared to the standard offset variant with 100% after 13.5 years (log rank test p = 0.0283). Chi square test also revealed a significantly higher risk of breakage of lateralized necks compared to standard offset pieces (p = 0.0141). Three of four patients were obese with a mean BMI of 37.9 kg/m2. Grade of obesity (grade 1 or higher) had significant influence on risk of breakage. Survival of the implant was significantly lower in obese patients with at least grade 1 obesity compared to patients with a BMI < 30 kg/m2 (82.9 (95% CI: 64.9–100%) after 11.6 years vs. 98.4 (95% CI: 95.3–100%) after 13.7 years; log-rank p = 0.0327). Conclusions: Cumulative risk for failure of taper junctions was high in this consecutive single institutional cohort and may further increase during follow-up. As independent data acquisition in registries is missing, failure rate may be higher than reported data of the manufacturers. The use of lateralized offset necks in obese patients of at least grade 1 obesity showed a significantly higher risk of breakage. The use of monobloc revision devices may be an option, but randomized control trials are currently missing to establish standardized treatment protocols considering individual risks for both monobloc and/or modular implants.

Femoral defects in revision hip arthroplasty: a therapy-oriented classification

INTRODUCTION

The complex field of femoral defects in revision hip arthroplasty displays a lack of standardized, intuitive pre- and intraoperative assessment. To address this issue, the femoral defect classification (FDC) is introduced to offer a reliable, reproducible and an intuitive classification system with a clear therapeutic guideline.

MATERIALS AND METHODS

The FDC is based on the integrity of the main femoral segments which determine function and structural support. It focuses on the femoral neck, the metaphysis consisting of the greater and lesser trochanter, and the femoral diaphysis. The four main categories determine the location of the defect while subcategories a, b and c are being used to classify the extent of damage in each location. In total, 218 preoperative radiographs were retrospectively graded according to FDC and compared to intraoperatively encountered bone defects. To account for inter-rater and intra-rater agreement, 5 different observers evaluated 80 randomized cases at different points in time.

RESULTS

A Cohens kappa of 0.832 ± 0.028 could be evaluated, accounting for excellent agreement between preoperative radiographs and intraoperative findings. To account for inter-rater reliability, 80 patients have been evaluated by 5 different observers. Testing for inter-rater reliability, a Fleiss Kappa of 0.688 could be evaluated falling into the good agreement range. When testing for intra-rater reliability, Cohens Kappa of each of the 5 raters has been analyzed and the mean was evaluated at 0.856 accounting for excellent agreement.

CONCLUSION

The FDC is a reliable and reproducible classification system. It combines intuitive use and structured design and allows for consistent preoperative planning and intraoperative guidance. A therapeutic algorithm has been created according to current literature and expert opinion. Due to the combination of the FDC with the recently introduced Acetabular Defect Classification (ADC) a structured approach to the entire field of hip revision arthroplasty is now available.

[Strategies for stem revision : Surgery planning, implant removal and reimplantation]

BACKGROUND AND PLANNING

Femoral revision represents a challenging procedure in its surgical planning and technical execution. The results are mainly dependent on the bone loss present, the quality of the implant removal and the choice of revision system. Patient-specific factors such as age, comorbidities, bone quality or even the localization of the cement have a decisive influence on the surgical strategy. Appropriate preoperative preparation, including the presence of the necessary special instruments, which are essential for gentle implant removal, is indispensable to achieve the best possible result.

THERAPY

A bone-sparing implant removal can be particularly challenging, especially in the case of well-fixed stems and cement residues, which may extend far beyond the isthmus. In such situations, a transfemoral approach should be considered. Cementless reimplantation using modular or non-modular titanium stems is currently the preferred treatment of choice for most revisions. In elderly, low-demand patients or with poor bone quality, cemented revision remains a good alternative treatment option.

Revision Hip Arthroplasty Using a Modular, Cementless Femoral Stem: Long-Term Follow-Up

BACKGROUND

As the number of primary total hip arthroplasty (THA) cases increase, so does the demand for revision operations. However, long-term follow-up data for revision THA is lacking.

METHODS

A retrospective review was completed of patients who underwent revision THA at a single institution between January 2002 and October 2007 using a cementless modular stem. Patient demographic, clinical, and radiographic data was collected. Preoperative and postoperative patient-reported outcome scores were compared at a minimum of fourteen-year follow-up.

RESULTS

Eighty-four patients (89 hips) with a median age of 69 years (range, 28 to 88) at operation were included. Indications for revision included aseptic loosening (84.2%), infection (12.4%), and periprosthetic fracture (3.4%). Twenty-two hips sustained at least 1 complication: intraoperative fracture (7.9%), dislocation (6.7%), prosthetic joint infection (4.5%), deep venous thrombosis (3.4%), and late periprosthetic fracture (2.2%). There were no modular junction complications. Eight patients underwent reoperations; only three involved the stem. Thirty-eight patients (45%) were deceased prior to final follow-up without known reoperations. Twenty-seven patients (32%) were lost to follow-up. Twenty-one patients (23%) were alive at minimum fourteen-year follow-up. Complete patient-reported outcomes were available for nineteen patients (range, 14 to 18.5 years of follow-up). Significant improvement was seen in UCLA activity, VR-12 physical, hip disability and osteoarthritis outcome score , joint replacement., and Harris Hip score pain and function scores.

CONCLUSION

Challenges of long-term follow-up include patient migration, an unwillingness to travel for re-examination, medical comorbidities, advanced age, and death. The cementless modular revision stem demonstrated long-term clinical success and remains a safe and reliable option for complex revision operations.

Cementless primary or revision stem in revision hip arthroplasty for aseptic stem loosening with Paprosky type I/II femoral defect?

BACKGROUND

The use of primary or revision stem during revision total hip arthroplasty (THA) for aseptic stem loosening with Paprosky type I/II femoral defect remains controversial. The aim of this study was to compare the outcomes of patients who underwent revision THA with a primary or revision stem.

METHODS

We retrospectively reviewed 78 patients who received revision THA for aseptic stem loosening using primary (N = 28) or revision stems (N = 50). The bone defects were classified as Paprosky type I or II. The mean follow-up duration was 72.3 ± 34.7 months. The primary outcome domains included surgical complications and implant failures. The secondary outcome domains included medical complications, 30- and 90-day readmission, and Harris hip score (HHS).

RESULTS

The use of revision stem was associated with a higher incidence than primary stem of patient complications (60.0% vs. 32.1%, p = 0.018), including intraoperative femur fracture (28.0% vs. 7.1%, p = 0.029) and greater trochanter fracture (16.0% vs. 0%, p = 0.045). The implant survival rate was comparable between groups. HHS at the final follow-up was similar.

CONCLUSION

With a lower risk of surgical complications and a similar rate of mid-term implant survival, cementless primary stem appears superior to revision stem in revision THA for aseptic stem loosening with Paprosky type I/II femoral defect.

Clinical, functional and radiographic outcomes after revision total hip arthroplasty with tapered fluted modular or non-modular stems: a systematic review

PURPOSE

The aim of the study was to systematically evaluate clinical outcomes of tapered fluted stems, either monoblock or modular, in revision total hip arthroplasty.

METHODS

PubMed, EMBASE and Web of Science and Cochrane databases were systematically searched by 2 researchers. Clinical studies reporting primarily on survival and re-revision rates, and secondarily on subsidence, dislocation, intraoperative fractures, periprosthetic fractures and infection were included. 2 investigators assessed the quality of the studies.

RESULTS

46 studies were included in this review, reporting on 4601 stem revisions. The pooled re-revision rate was 5.1% and long-term survival ranged from 75% to 98.5%. No differences were observed between monoblock and modular stems regarding re-revision rate, dislocation rate, periprosthetic fracture rate or infection rates. Monoblock stems exhibited more subsidence and modular stems displayed more intraoperative fractures.

CONCLUSIONS

Satisfactory results can be obtained with the use of tapered fluted end-bearing stems. Monoblock stems offer the same clinical results as modular stems.

Which length should the neck segment of modular revision stems have?

BACKGROUND

Fractures of modular revision stems at the taper junction are rare but severe clinical problems. The purpose of this study was the estimation of taper loading to identify configurations which are less prone to failure.

METHODS

A parametrical analytical 3-D model was developed to determine the influence of neck segment length, offset and anteversion on the loading at the modular taper junction between neck segment and stem. Published in-vivo hip joint forces were used to simulate different activities.

FINDINGS

No unique ideal neck segment length can be specified due to the differences in loading magnitude and direction between activities. The best neck segment length for walking is longer than for high loading activities as stair climbing and jogging. A medium length between 70 mm and 90 mm appears to be a good compromise. A shorter offset (37 mm vs. 47 mm) reduces the stress by about 25% for walking and jogging. Retroverted implantation by 5° increases the loading whereas an anteverted implantation by 5° reduces it. A high offset (47 mm) combined with a short neck segment length (50 mm) reaches about 80% of the taper yield strength for jogging (taper diameter 13 mm).

INTERPRETATION

Simplified 2-D modelling falsely predicts no bending at the taper junction for a long neck segment, whereas the 3-D model shows substantial stress load along the whole stem length. Stem tapers of short as well as very long neck segments are higher risk for failure. Neck segment length should lie in the range between 70 mm and 90 mm.

Osteoanabolic Treatment with Teriparatide for Pathological Stress Transfer After Total Hip Arthroplasty: A Case Report

CASE

Total hip arthroplasty with an uncemented, tapered, fluted stem was performed in a 79-year-old woman with known osteoporosis to treat an intertrochanteric fracture. Exertional thigh pain and cortical thickening developed at the tip of the stem. The patient was treated with teriparatide for a total of 2 years and became asymptomatic within months. Radiographs showed improved bone quality around the stem of the prosthesis, and dual-energy x-ray absorptiometry scans confirmed remineralization.

CONCLUSION

Stem tip pain is a well-known complication of distally engaging arthroplasty implants. Various surgical options have been suggested to address this condition. Teriparatide is known to help prevent fractures and improve bone healing. This successful off-label use might be of interest for the future treatment of this biomechanical complication.

Primary stability of a cementless modular revision hip stem in relation with the femoral defect size: A biomechanical study

PURPOSE

Cementless modular fluted hip stems are commonly used in revision arthroplasty. Nevertheless, there is a wide spectrum of recommendations concerning the minimum bone stock required to enable osseous ingrowth and implant-bone micromotions <100 µm. This experimental study investigated the primary stability of a tapered cementless fluted revision stem depending on different types of bone defects.

METHODS

Implant-bone interface movements with a bimodular stem were examined under cyclic axial and torsional loading using composite femora. In four degrees of freedom, the implant subsidence and micromotions were captured with linear variable differential transformers for the intact femora and seven different defects ranging from Paprosky type I to type IIIB.

RESULTS

With a 7-cm length of intact diaphysis proximal to the isthmus (Paprosky IIIA), mean implant-bone micromotions of 66 µm occurred. An implant-bone contact zone of only 5 cm (Paprosky IIIA) resulted in micromotions notably over 100 µm and significantly increased subsidence (p < 0.05). With a Paprosky IIIB defect (3 cm of intact diaphysis) rotational instability occurred in all specimens.

CONCLUSIONS

Aside from critically increased interfacial micromotions (>100 µm), rotational instability emerged as a mechanism of fixation failure when the implant-bone contact zone was only 5 cm or less. Hence, future studies investigating the implant fixation in the case of femoral bone defects should consider both axial and torsional loading. With regard to the clinical application, our data suggest maintaining 7 cm of diaphyseal implant-bone contact for a safe anchorage of cementless fluted hip revision stems.

Femoral Stem Fracture in Hip Revision Arthroplasty: A Systematic Literature Review of the Real-World Evidence

Background Total hip arthroplasty (THA) presents as an excellent treatment for the osteoarthritic hip, demonstrating good survival rates. However, aseptic loosening and infection are the main causes of operative revision. The methods used in revision surgery are non-modular or modular THA implants. In addition to the abovementioned revision reasons for THA, this treatment could be associated with the possibility of femoral stem fracture, especially in the modular system. The topic of material failure has been focused on in the public media. The question arises as to how such media reports correlate with the published literature. The observed mentioned number of cases concerning a femoral stem fracture vary between one single case and up to 18.5% within a clinical study, thus presenting an inhomogeneous data situation with a large span. The specific aim of this systematic review is to establish facts and clarify the number of unforeseen events of a femoral stem fracture based on peer review articles and registry data. This clarification is important to us, as these media reports have led to uncertainty among patients.

Methods A systematic review was performed in accordance with the PRISMA statement. Peer review articles in English and German, presenting original articles, meta-analyses, or case reports, were searched from the turn of the millennium up to December 2019. Only articles that reported a femoral stem component fracture, with content of clinical data as well as register data, were included. Relevant papers published after the defined research time frame were taken into account within the discussion.

Results In total, 218 fractures of a femoral stem (141 primary and 77 revision THA) component could be identified within the selected literature. Most cases of a femoral stem fracture occurred in the modular THA implants compared to the non-modular stems. Regarding revision THA, in summary, 77 implants, presenting 23 non-modular and 54 modular implants, failed by means of femoral stem fracture. A review of 11 National Joint Registries shows a revision rate between 0.04 and 0.05% in only 2 registers according to the specific subject of a femoral stem fracture. For the remaining 9 registers, however, detailed information is lacking and only nonspecific information such as a generic “implant failure” or “other reason” (which can cover a multitude of causes) is supplied.

Conclusion A femoral stem fracture presents a devastating complication for the patient, the surgeon as well as for the manufacturer of the implant. Modular THA implants play an increasingly valuable role concerning restoration of individual anatomy in modern THA revision surgery, especially within complex cases. Regarding revision procedures, data suggests a lower risk of femoral stem fracture for modular implants compared to primary procedures, while the risk of fracture for non-modular implants seems to increase during revision. Ultimately, it cannot be proven whether this is actually applicable, since the absolute number of implanted prosthesis systems is not known. Various implant-, patient-, and surgeon-related factors may lead to these reported femoral stem fractures. However, this systematic review suggests that this is, in general, a rare complication.

Modular tapered conical revision stem in hip revision surgery: mid- term results

BACKGROUND

The aim of this paper is to evaluate the clinical and radiological outcomes of a fluted tapered modular distal-fixation stem at medium to long-term follow-up. The hypothesis of this investigation was to verify if the use of this implant design may have provided potential advantages in femoral revisions and post-traumatic instances where the restoration of the anatomy was the prime concern.

METHODS

We retrospectively reviewed 62 cases of femoral revision surgeries, performed in Paprosky type IIIA and IIIB bone defects between January 2001 and December 2011 with a mean follow-up of 8.5 ± 1.5 years (range 5.1-15.9 years) where a modular fluted stem was used. The clinical assessment was performed with the Harris Hip Score (HHS), and the radiographic evaluation was carried in order to assess the stability of the femoral component. Intra-operative and postoperative complications were recorded, and the rates of complications and revisions for any cause were determined.

RESULTS

Mean HHS improved 35.4 points from the preoperative assessment. Radiographic evaluation showed a stable stem anchorage in 90.3% of the cases at the last follow-up. Five (8%) implants required additional surgery. Neither breakage of the stem nor loosening of the taper junction were recorded. Kaplan-Meier survivorship was 89.4% (CI: 88.8-90%) for any complication and 92.3% (CI: 91.8-92.7%) according to revision for any causes at 81 months follow-up.

CONCLUSIONS

Our findings suggest that this stem design is a reliable option in cases of complex femoral bone defects, as well as in cases with high functional deficiencies, with promising survivorship.

Revision Hip Arthroplasty Using a Porous-coated or Taper ZMR Implant: Minimum 10-year Follow-up of Implant Survivorship

INTRODUCTION

The Zimmer Modular Revision hip (ZMR) system is available in two stem options, a porous-coated cylindrical (PCM) and a taper (TM) stem. Several concerns have been reported regarding modular implants. Specifically, because of early junctional fractures, the ZMR system was redesigned with a wider modular interface. As such, we designed a study assessing long-term ZMR survivorship and functional and radiographic outcomes.

METHODS AND MATERIALS

A search of our institutional research database was performed. A minimum 10-year follow-up was selected. The following two cohorts were created: PCM and TM stems. The Kaplan-Meier survival analysis was performed, and causes of stem failure requiring revision surgery were collected. Functional outcomes as per the Harris Hip Score and radiographic stem stability were assessed as per the Engh classification.

RESULTS

A total of 146 patients meeting the inclusion criteria were available for follow-up (PCM = 68, TM = 78). The mean follow-up was 13.4 years clinically and 11.1 years radiographically for the PCM cohort. Similarly, the TM cohort had a follow-up of 11.1 years clinically and 10.5 years radiographically. The Kaplan-Meier survivorships were 87.1% and 87.8% at 15 years for the PCM and TM cohorts, respectively. The most common cause of failure requiring revision surgery overall was aseptic loosening (PCM = 1.4%, TM = 5.6%). The mean postoperative Harris Hip Score was as follows: PCM = 71.2 and TM = 64.7. Engh type I or II stem ingrowth was as follows: PCM = 85% and TM = 68%.

DISCUSSION

Good survivorship using the ZMR stem system can be expected at up to 15 years. Aseptic loosening remains the most commonly encountered problem for both PCM and TM stems. Previously identified modular junctional weakness seem to have been addressed.

Clinical, radiographic, and survivorship analysis of a modular fluted tapered stem in revision hip arthroplasty

PURPOSE

Modular fluted tapered stems are one of the most commonly used implants in femoral revision surgery. Due to the relative lack of studies on the Restoration modular fluted tapered stem, we conducted a study to evaluate its short- to mid-term clinical, radiographic, and survival outcomes.

METHODS

We identified all 45 patients treated with this revision stem at our institution. Five patients did not complete the minimum 2-year follow-up, leaving 40 patients (41 hips) for assessment. Mean follow-up was 5.1 years (range 2-11 years). Clinical outcomes were assessed using the Harris hip score (HHS). Radiographs were evaluated for subsidence and loosening. Kaplan-Meier survival analysis was performed using revision of the stem for any reason as end point.

RESULTS

The mean HHS improved from 44.6 points preoperatively to 78.4 points at the most recent follow-up (p < 0.0001). Nonprogressive subsidence occurred in 83% of the hips (mean 2.8 mm; range 1-7 mm). One stem (2.4%) showed progressive subsidence (20 mm) and was considered loose. The most common cause for reoperation was dislocation (three hips, 7.3%). The 10-year survivorship with revision of the stem for any reason as the end point was 93.5% (95% CI, 84.9-100%).

CONCLUSION

There was a significant improvement in the HHS and a low likelihood of revision at short- to mid-term follow-up, adding to the current evidence base for use of this implant in revision surgery. A longer follow-up and a larger number of cases are necessary to fully evaluate its role and performance.

Micromotion and subsidence of a cementless conical fluted stem depending on femoral defect size - A human cadaveric study

BACKGROUND

Cementless modular endoprostheses with tapered fluted stems cover a wide spectrum of femoral defects in reconstructive surgery of the hip. Nevertheless, for these hip stems the recommendations concerning the minimum diaphyseal anchorage distance differ widely. The present experimental study investigated the primary stability of a conical fluted revision stem depending on different types of femoral bone defects.

METHODS

Using six fresh frozen human femora, the relative movement of a bi-modular revision stem within the implant-bone interface was examined under cyclic loading conditions. Implant subsidence as well as micromotions at the bone-implant interface were captured with linear variable differential transformers for the intact femora and three different defects ranging from Paprosky type II to type IIIB.

FINDINGS

Compared to the intact femur, the infliction of a Paprosky type IIIB defect (3 cm of intact diaphysis) notably increased mean stem subsidence (13-389 μm per 500 load cycles; P = 0.116) but the mean interface micromotion vector sum remained unchanged (50 μm vs. 53 μm). In Paprosky IIIB defects the subsidence component resulting from rotation (horizontal plane) was significantly higher than with the intact femur and a Paprosky II defect (P ≤ 0.041).

INTERPRETATION

With optimal bone quality and ideal femur preparation a 3 cm conical fixation was sufficient to meet the set criteria of bony ingrowth in vitro. A conical fixation of 7 cm should be recommended to limit rotational subsidence, especially in case of impaired diaphyseal bone quality or expected difficulties with partial weight-bearing.

Is There a Benefit to Modularity for Femoral Revisions When Using a Splined, Tapered Titanium Stem?

BACKGROUND

Proposed benefits of modularity for femoral revisions in total hip arthroplasty (THA) include more precise biomechanical restoration and improved stability, but this has not been proven with use of a splined, tapered design. This study's purpose is to compare (1) complication rates, (2) functional outcomes, and (3) radiographic measures of subsidence, offset, and leg length discrepancy with the use of modular vs monoblock splined, tapered titanium stems in revision THA.

METHODS

We retrospectively reviewed 145 femoral revisions with minimum 2-year follow-up (mean, 5.12 years; range, 2-17.3 years). Patients receiving a modular (67) or monoblock (78) splined, tapered titanium stem for femoral revision were included.

RESULTS

There were no statistically significant differences in rates of reoperation (22.3% vs 17.9%; P = .66), intraoperative fracture (9.0% vs 3.8%; P = .30), postoperative fracture (3.0% vs 1.3%; P = .47), dislocation (11.9% vs 5.1%; P = .23), or aseptic loosening (4.5% vs 6.4%; P = .73) between the modular and monoblock cohorts, respectively. There were similar results regarding subsidence >5 mm (10.4% vs 12.8%; P = .22), LLD >1 cm (35.8% vs 38.5%; P = .74), restoration of hip offset (-5.88 ± 10.1 mm vs -5.07 ± 12.1 mm; P = .67), and Harris Hip Score (70.7 ± 17.9 vs 73.9 ± 19.7; P = .36) between groups. Multivariate regression showed no differences in complications (P = .44) or reoperations (P = .20) between groups.

CONCLUSION

Modular and monoblock splined, tapered titanium stems demonstrated comparable complication rates, functional outcomes, and radiographic parameters for femoral revisions. However, a limited number of patients with grade IIIB or IV femoral bone loss received a monoblock stem. Future investigations are required to determine whether modularity is beneficial for more complex femoral defects.

Mechanical failure of 113 uncemented modular revision femoral components

Aims

We evaluated a large database with mechanical failure of a single uncemented modular femoral component, used in revision hip arthroplasty, as the end point and compared them to a control group treated with the same implant. Patient- and implant-specific risk factors for implant failure were analyzed.

Methods

All cases of a fractured uncemented modular revision femoral component from one manufacturer until April 2017 were identified and the total number of implants sold until April 2017 was used to calculate the fracture rate. The manufacturer provided data on patient demographics, time to failure, and implant details for all notified fractured devices. Patient- and implant-specific risk factors were evaluated using a logistic regression model with multiple imputations and compared to data from a previously published reference group, where no fractures had been observed. The results of a retrieval analysis of the fractured implants, performed by the manufacturer, were available for evaluation.

Results

There were 113 recorded cases with fracture at the modular junction, resulting in a calculated fracture rate of 0.30% (113/37,600). The fracture rate of the implant without signs of improper use was 0.11% (41/37,600). In 79% (89/113) of cases with a failed implant, either a lateralized (high offset) neck segment, an extralong head, or the combination of both were used. Logistic regression analysis revealed male sex, high body mass index (BMI), straight component design, and small neck segments were significant risk factors for failure. Investigation of the implants (76/113) showed at least one sign of improper use in 72 cases.

Conclusion

Implant failure at the modular junction is associated with patient- and implant-specific risk factors as well as technical errors during implantation. Whenever possible, the use of short and lateralized neck segments should be avoided with this revision system. Implantation instructions and contraindications need to be adhered to and respected. Cite this article: Bone Joint J 2020;102-B(5):573–579.

Radiographic and Clinical Outcomes of Modular Tapered Fluted Stems for Femoral Revision for Paprosky III and IV Femoral Defects or Vancouver B2 and B3 Femoral Fractures

BACKGROUND

Extensive femoral bone loss poses a challenge in revision total hip arthroplasty (rTHA). Many techniques have been developed to address this problem including fully porous cylindrical stems, impaction bone grafting, and cementation of long stems, which have had varied success. Modular tapered fluted femoral stems (MTFS) show favorable results. We sought to determine the minimum 2-year radiographic and clinical performance of MTFS in rTHA in a population with extensive proximal femoral bone loss.

METHODS

Our clinical database was queried retrospectively for all patients who underwent rTHA with an MTFS. We included patients with Paprosky 3 and 4 femoral bone loss and patients with Vancouver B2 and B3 periprosthetic femur fractures. Patients without 2-year follow-up were invited to return to clinic for X-ray evaluation and to complete clinical questionnaires. We assessed distance of stem subsidence and presence of stem fixation on final X-ray. We recorded all-cause revision and survival of the stem at final follow-up.

RESULTS

One hundred twenty-nine patients were available for follow-up. Average follow-up time was 3.75 years. One hundred twenty-two stems (95%) remained in place at final follow-up. Median subsidence was 1.4 mm (range 0-21). All-cause revision rate was 16.3% (21 patients). Of the hips revised, 10 were for instability, 6 for infection, 1 for aseptic loosening, and 1 for periprosthetic femur fracture. Three were revised for other reasons. The stem was revised in 7 patients (5.4%), and the most common reason for stem revision was infection (5 patients). The other 2 stems were revised for aseptic loosening in a Paprosky 4 femur and periprosthetic femur fracture. Survival of tapered modular fluted stems with aseptic failure as an endpoint was 98.4%. The mean Hip disability and Osteoarthritis Outcome Score, Joint Replacement score at final follow-up was 73, and mean Veterans Rand 12 item health survey physical and mental scores were 32.8 and 52.2, respectively.

CONCLUSION

In patients with Paprosky 3, 4 femoral defects or Vancouver type B2, B3 fractures, modular tapered fluted stems for femoral revision show excellent outcomes at minimum 2-year follow-up.

High survivorship of highly cross-linked polyethylene in revision Total hip Arthroplasty: a minimum 10-year follow-up study

Purpose

Highly cross-linked polyethylene has been introduced to decrease osteolysis secondary to polyethylene wear debris generation. However, few long-term data on revision total hip arthroplasty (THA) using highly cross-linked polyethylene liners are available. The objective of this study was to determine long-term outcomes of a highly cross-linked polyethylene liner in revision THA.

Materials & methods

We evaluated 63 revision THAs performed in 63 patients using a highly cross-linked polyethylene liner between April 2000 and February 2005. Of these, nine died and four were lost to follow-up. Thus, the final study cohort consisted of 50 patients (50 hips), including 26 males and 24 females with a mean age of 53 years (range, 27–75 years). Mean follow-up was 11 years (range, 10–14 years).

Results

The mean Harris hip score improved from 44 points preoperatively to 85 points at the final follow-up. No radiographic evidence of osteolysis was found in any hip. The mean rate of polyethylene liner wear was 0.029 mm/year (range, 0.003 to 0.098 mm/year). A total of 5 hips (10%) required re-revision arthroplasty, including one cup loosening, one recurrent dislocation, and three deep infections. Kaplan-Meier survivorship with an end point of re-revision for any reason was 91.1% and for aseptic cup loosening was 97.9% at 11 years.

Conclusion

At a minimum of 10 years, the highly cross-linked polyethylene liners showed excellent clinical performance and implant survivorship, and were not associated with osteolysis in our patients with revision THAs.

Anchoring of a Kinked Uncemented Femoral Stem after Preparation with a Straight or a Kinked Reamer

Objective

To investigate a stem‐adjusted preparation of the femur with a kinked reamer and to determine whether this approach results in higher primary stability of a kinked stem than straight reaming of the intramedullary canal.

Methods

Ten cementless stems with a kinked design were implanted in synthetic femurs after preparation of the femoral canal with 2 different reamer designs (straight reaming [SR] group vs kinked reaming [KR] group). The specimens were analyzed using CT to determine the anchoring length and examined with a mechanical testing system to establish their axial stiffness, torsional stiffness, and migration distance after 10 000 gait cycles.

Results

The stem migration distances did not differ significantly between the groups (SR group 0.51 ± 0.16 mm vs KR group 0.36 ± 0.03 mm, P = 0.095). Only for the SR group, a correlation was found between the completely conical anchorage length and absolute stem migration (P < 0.05, R = 0.89). Regarding the torsional stiffness, no differences were observed between the study groups (SR group 6.48 ± 0.17 Nm/° vs KR group 6.52 ± 0.25 Nm/°, P = 0.398). In the KR group, significantly higher axial stiffness values were measured than in the SR group (SR group 1.68 ± 0.14 kN/mm vs KR group 2.09 ± 0.13 kN/mm, P = 0.008).

Conclusions

The implantation of a kinked stem after kinked conical intramedullary preparation of the proximal femur showed equivalent results regarding anchoring length, stem migration, and torsional stiffness to those for straight conical reaming. The specimens with kinked reaming showed significantly higher axial stiffness values.

Outcomes of neck modularity in total hip arthroplasty: an Italian perspective

BACKGROUND

The aim of this study is to conduct a systematic review of clinical outcomes and complications of modular neck THA among Italian cohorts.

METHODS

Only reviewed publications focused on Italian cohort patients in English language were considered for inclusion. Studies were included if they involved patients who underwent total hip replacement surgery with modular necks, and reported aetiology or survival rate or bone stability or clinical scores or complications.

RESULTS

The studies included in our search reported data on 3714 patients and 3856 hips. Most of the studies were from high-volume surgery centres. The most frequent diagnosis was osteoarthritis that occurred in 2910 cases (75.9%). The average survival rate and average bone stability were 97.20% and 99.37%, respectively. The average HHS improved from 42.1 prior to surgery to 89.52 after surgery. Studies included in our search reported 40 complications. The most frequently reported complication was dislocation (40%).

CONCLUSION

This review showed excellent survival rate and bone stability and good clinical outcomes in Italian cohort patients treated with modular neck THA, and these clinical results are comparable with international cohort rates. This review suggests that modular implants represent a very satisfying choice when practised by expert orthopaedic joint surgeons.

Cementless revision femoral stems application of press-fit principles and clinical outcomes

BACKGROUND

Cementless femoral stems are currently used in revision total hip arthroplasty (THA) with the surgeon choosing between various fixation modes. The outcomes are good in the medium term; however, some failures have been attributed to technical errors during implantation. When the decision has been made to use a press-fit implant, the impact of the surgeon's technique on the functional outcomes have not been explored in-depth. This led us to carry out a retrospective study on a large population of total hip arthroplasty patients which aims were achieved press-fit to (1) determine the impact of the type of primary fixation (with and without press-fit) on the functional outcomes; (2) specify the effect of stem length on the functional scores when diaphyseal press-fit is achieved and (3) analyse the main reasons why a true press-fit effect was not achieved (three-point fixation).

HYPOTHESIS

There is a relationship between the primary fixation method by press-fit of a revision femoral stem and the functional outcomes.

PATIENTS AND METHODS

We performed a retrospective analysis of a continuous cohort of 244 THA revision cases with a mean follow-up of 6.1 ± 3.5 years (range, 2-18). The femoral area in which close contact was achieved (shared interface between the bone and implant) was used to define various types of press-fit fixation. The functional outcomes were determined using the Harris Hip Score (HHS) and the Merle d'AubignéPostel score (MAP score) out of 12 points (pain and walking items).

RESULTS

The post-operative HHS averaged 90.83 ± 7.51 for proximal press-fit and 80.14 ± 14.93 with no press-fit (p = 0.01). The MAP averaged 10.83 ± 1.03 for proximal press-fit and 9.75 ± 2.09 with no press-fit (p = 0.09). The MAP score was worse for long diaphyseal press-fit than for short press-fit (p = 0.02). Use of a long stem with an endofemoral route or an overly small femoral window in patients with a curved femur is the main reason that three-point fixation occurred instead of press-fit.

CONCLUSIONS

While press-fit is an effective concept, it is a demanding one that requires the surgeon to choose the correct surgical strategy for the patient's anatomy. A meticulous surgical technique is required to achieve proximal press-fit or at a minimum, short diaphyseal press-fit.

Relative radiographic bone density measurement in revision hip arthroplasty and its correlation with qualitative subjective assessment by experienced surgeons

BACKGROUND

Conventional radiography (CR) is the imaging method of choice in monitoring bone remodelling and other stability parameters after total hip arthroplasty (THA). Quantitative roentgen- or computed-tomography-based methods to determine bone density are prone to metal artifacts and often very costly, which is why they are not used as standard in a clinical setting. Since subjective assessment of bone remodelling in CR also has a certain susceptibility to errors, semi-quantitative methods have been developed to help approximate periprosthetic bone density development via CR to open up an additional tool for documentation of radiographic THA follow-up.

OBJECTIVE

Proof-of-principle of a newly designed imaging-software-aided method to measure relative bone density around the femoral stem in a series of conventional radiographs following THA.

METHODS

Eighty-six patients with hip modular tapered, fluted titanium stems were selected from the clinical database and series of baseline and postoperative follow-up radiographs were obtained after 24 and 48 weeks. Relative bone densities were measured per Gruen zones G1-7 with the use of an open-source image analysis package (ImageJ) by means of greyscale histograms. In addition, subjective evaluation of selected cases was performed by three independent, blinded orthopedic surgeons. Besides descriptive and nonparametric analyses, intra-class correlation (ICC) was performed and objective and subjective results were compared by linear regression analysis.

RESULTS

Two individual cases are presented as a proof-of-principle. Increase or decrease of bone density could be measured correctly over time in each case. In a collective analysis there were no significant differences in mean relative bone densities between groups after 24 and 48 weeks, although a positive tendency was visible towards increased bone formation over time. Individual analyses by Gruen zones revealed that some zones, namely the proximal ones (e.g. G6), exhibit a broader scattering than others over time. This could be explained by the design of the evaluated tapered revision stem that achieves distal fixation and allows for proximal micromotion. Correlation analysis with subjective ratings (inter-rater reliability ICC = 0.71) showed a positive correlation with objective results, suggesting a feasibility of the method for clinical use.

CONCLUSIONS

In conclusion the presented method is an easy and accessible tool to quantify relative bone density changes during THA follow-up. It shows a positive correlation to established subjective assessment of bone remodelling and may therefore serve as a quantitative supplement in clinical documentation.

Cementless One-Stage Revision in Chronic Periprosthetic Hip Joint Infection. Ninety-One Percent Infection Free Survival in 56 Patients at Minimum 2-Year Follow-Up

BACKGROUND

Cementless 1-stage revision in chronic periprosthetic hip joint infections is limited evaluated. The purpose of this study was to evaluate a specific treatment protocol in this patient group.

METHODS

The study was performed as a multicenter, proof-of-concept, observational study with prospective data collection. Patients were treated with a cementless 1-stage revision according to the CORIHA protocol between 2009 and 2014. Fifty-six patients, McPherson type III-A/B-1/2, were enrolled with a mean follow-up time from the CORIHA procedure of 4 years (minimum of 2 years). The primary outcome was re-revision performed due to infection and was evaluated by competing risk analysis, with death and aseptic revision as competing events. All-cause mortality was evaluated by Kaplan-Meier survival analysis. Oxford Hip Score (OHS) was used as disease-specific patient-reported outcome measure.

RESULTS

The cumulative incidence of re-revision due to infection was 8.9% (confidence interval [CI] 3.2%-18.1%). The 1-year and 5-year survival incidence was 96% (CI 86%-99%) and 89% (CI 75%-95%). OHS at baseline was 19.9 (CI 17.3-22.6) and at 24-month follow-up 35.1 (CI 31.7-38.5). The mean change in OHS from baseline to 24-month follow-up was 11.8 points (CI 7.3; 16.3). Three patients had aseptic revision performed: two suffered periprosthetic fractures and one had stem subsidence. Failure analysis of the 5 reinfections did not detect a clear pattern as to the cause of failure.

CONCLUSION

We found that cementless 1-stage revision in chronic periprosthetic hip joint infections has low reinfection rates in selected patients and may be applicable as a first-line treatment.

Mid-term results of revision total hip arthroplasty with an uncemented modular femoral component

INTRODUCTION

During revision total hip arthroplasty (THA), the surgeon commonly faces deficient proximal femoral bone. In this situation, distal fixation of the prosthesis is required. The aim of the current retrospective study is to assess the clinical and radiographic mid-term outcome of revision total hip arthroplasty using a modular uncemented, tapered, grit-blasted, distal straight stem system.

METHODS

This retrospective study included 70 femoral revisions that were performed in 67 patients using the device of interest. All patients were operated on via an extended trochanteric osteotomy. 60 revisions were performed as 1-stage (12 infected) and 10 as 2-stage (all infected) revisions. At 3 months postoperatively and at final follow-up, patients were assessed radiographically for the presence of osteolysis and for distal integration.

RESULTS

The mean follow-up time was 4.3 (2.0-7.6) years. 4 patients had a removal of at least 1 prosthetic component. Stem survival for any reason was 92% after 5 years (95% confidence interval [CI], 83%-100%). With aseptic loosening of the stem as the endpoint of interest, survival after 5 years was 96% (95% CI, 88%-100%). A postoperative subsidence rate of 14.7% was found. No perioperative femoral fractures were found in the current patient series.

CONCLUSIONS

This study showed excellent mid-term survival and good clinical and radiographic outcomes in patients who had undergone revision THA with a modular uncemented, tapered, straight design.

Nonmodular Tapered Fluted Titanium Stems Osseointegrate Reliably at Short Term in Revision THAs

BACKGROUND

The ideal femoral component for revision THA is undecided. Cylindrical nonmodular stems have been associated with stress shielding, whereas junctional fractures have been reported with tapered fluted modular titanium stems. We have used a tapered fluted nonmodular titanium femoral component (Wagner Self-locking [SL] femoral stem) to mitigate this risk. This component has been used extensively in Europe by its designer surgeons, but to our knowledge, it has not been studied in North America. Added to this, the design of the component has changed since early reports.

QUESTIONS/PURPOSES

We asked: (1) Does the Wagner SL stem have low rates of rerevision and other complications at a minimum 2 years after surgery? (2) Is the Wagner SL stem associated with high levels of patient function and pain relief at a minimum 2 years after surgery? (3) Does the Wagner SL stem have low rates of subsidence at a minimum 2 years after surgery? (4) Is the Wagner SL stem associated with proximal femoral bone remodeling at a minimum 2 years after surgery?

METHOD

Between May 2011 and December 2012, we performed 198 femoral revisions, of which 104 (53%) were performed using the Wagner SL femoral stem; during that period, our institution gradually shifted toward increasing use of these stems for all but the most severe revisions, in which modular fluted stems and proximal femoral replacements still are used on an occasional basis. Median followup in this retrospective study was 32 months (range, 24-46 months), and one patient was lost to followup before the 2-year minimum. The femoral deformities in this series were Paprosky Type I (10 hips), Paprosky Type II (26), Paprosky Type IIIA (52), Paprosky Type IIIB (nine), and Paprosky Type IV (two). Functional assessment was performed using the Oxford Hip Score (OHS), WOMAC, SF-12, and the University of California Los Angeles (UCLA) activity score. All complications and cases of revision were documented. All patients had radiographs performed within 1 year of the latest followup. These were assessed by two surgeons for signs of proximal femoral bone remodeling and subsidence.

RESULTS

Complete preoperative scores were available for 98 patients (98 of 104; 94%). The mean OHS preoperatively and at final followup were 39 (SD, 15) and 87 (SD, 19), respectively (p < 0.001; mean difference, 48; 95% CI, 43-53). Average WOMAC scores were 44 (SD, 15) and 87 (SD, 20), respectively (p < 0.001; mean difference, 43; 95% CI, 38-48). At final followup, signs of restoration of proximal femoral bone stock was noted in 45 of 103 hips (44%). Six (six of 104; 6%) patients had subsidence of 10 mm to 15 mm. In the remainder (98 of 104; 94%), the mean subsidence was 2 mm (range, 0-9 mm). One revision was performed for loosening associated with infection.

CONCLUSIONS

The Wagner SL stem is a viable option for patients with Paprosky Types II and III defects undergoing revision THA. This component provides high levels of patient function with low revision rates and low rates of subsidence during the early postoperative phase. They provide a viable alternative to modular components for treatment of Types II and III defects without the risk of junctional fractures. They can be used for very selected Type IV defects, however this extent of bone loss is most easily addressed with other techniques such as a proximal femoral replacement.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Combining a hip arthroplasty stem with trochanteric reattachment bolt and a polyaxial locking plate in the treatment of a periprosthetic fracture below a well-integrated implant

Distally anchored uncemented modular tapered porous stems are often the preferred treatment in total hip arthroplasty revisions and failed subtrochanteric fractures. These conditions mainly affect elderly osteoporotic patients, with an increased risk of later fractures below the well-fixated implant. Treatment in secondary fractures with long looking plates is the recommended treatment, where stability is a key to fracture healing. We report a complicated case in which this was achieved by an innovative technique combing the trochanteric attachment bolt of the stem system and a locking plate with polyaxial screws.

Revision of hemiarthroplasty to total hip arthroplasty using the cement-in-cement technique

Revision of a cemented hemiarthroplasty of the hip may be a hazardous procedure with high rates of intra-operative complications. Removing well-fixed cement is time consuming and risks damaging already weak bone or perforating the femoral shaft. The cement-in-cement method avoids removal of intact cement and has shown good results when used for revision total hip arthroplasty (THA). The use of this technique for the revision of a hemiarthroplasty to THA has not been previously reported.

A total of 28 consecutive hemiarthroplasties (in 28 patients) were revised to a THA using an Exeter stem and the cement-in-cement technique. There were four men and 24 women; their mean age was 80 years (35 to 93). Clinical and radiographic data, as well as operative notes, were collected prospectively and no patient was lost to follow-up.

Four patients died within two years of surgery. The mean follow up of the remainder was 70 months (25 to 124). Intra-operatively there was one proximal perforation, one crack of the femoral calcar and one acetabular fracture. No femoral components have required subsequent revision for aseptic loosening or are radiologically loose.

Four patients with late complications (14%) have since undergone surgery (two for a peri-prosthetic fracture, and one each for deep infection and recurrent dislocation) resulting in an overall major rate of complication of 35.7%.

The cement-in-cement technique provides reliable femoral fixation in this elderly population and may reduce operating time and rates of complication.

Cite this article: Bone Joint J 2015;97-B:1623–7.

Revision total hip arthroplasty using cemented collarless double-taper femoral components at a mean follow-up of 13 years (8 to 20): an update

The outcome of 219 revision total hip arthroplasties (THAs) in 98 male and 121 female patients, using 137 long length and 82 standard length cemented collarless double-taper femoral stems in 211 patients, with a mean age of 72 years (30 to 90) and mean follow-up of six years (two to 18) have been described previously. We have extended the follow-up to a mean of 13 years (8 to 20) in this cohort of patients in which the pre-operative bone deficiency Paprosky grading was IIIA or worse in 79% and 73% of femurs with long and standard stems, respectively. For the long stem revision group, survival to re-revision for aseptic loosening at 14 years was 97% (95% confidence interval (CI) 91 to 100) and in patients aged > 70 years, survival was 100%. Two patients (two revisions) were lost to follow-up and 86 patients with 88 revisions had died. Worst-case analysis for survival to re-revision for aseptic loosening at 14 years was 95% (95% CI 89 to 100) and 99% (95% CI 96 to 100) for patients aged > 70 years. One additional long stem was classified as loose radiographically but not revised. For the standard stem revision group, survival to re-revision for aseptic loosening at 14 years was 91% (95% CI 83 to 99). No patients were lost to follow-up and 49 patients with 51 hips had died. No additional stems were classified as loose radiographically. Femoral revision using a cemented collarless double-taper stem, particularly with a long length stem, and in patients aged > 70 years, continues to yield excellent results up to 20 years post-operatively, including in hips with considerable femoral metaphyseal bone loss.

Mid-term Results of Revision Total Hip Arthroplasty Using Modular Cementless Femoral Stems

Purpose

The purpose of this study was to evaluate the clinical and radiological results of revision total hip arthroplasty using modular distal fixation stems for proximal femoral deficiency.

Materials and Methods

Forty-five patients (47 hips) were analyzed more than 24 months after revision total hip arthroplasty that used modular distal fixation stems and was performed between 2006 and 2012. There were proximal femoral defects in all cases. Preoperative femoral defect classification revealed Paprosky type II in 31 cases, type IIIA in 7, and type IIIB in 9. The mean duration of follow-up was 53.4 (25-100) months. We evaluated the Harris hip score (HHS), walking ability according to Koval as clinical parameters, stem stability, and stem position change as radiographic parameters. Kaplan-Meier survival analysis was performed.

Results

The average HHS improved form 39.5 points to 91.3 points and walking ability also improved in most cases; all patients had stable fixation of the femoral stem. Postoperative complications included 5 cases of infection and 2 cases of dislocation. The survival rate with the end point of re-revision surgery due to infection or dislocation was 86% after 8-year follow-up.

Conclusion

Cementless revision total hip arthroplasty using modular femoral stems is useful because the stems can be stably fixed on the diaphyseal portion of the femur, which has relatively good bone quality at mid-term follow-up.

Similar outcomes between two-stage revisions for infection and aseptic hip revisions

PURPOSE

Two-stage revision hip arthroplasty using an antibiotic-loaded spacer is the most widely performed procedure for infected hip arthroplasties. The clinical outcome of this type of surgery compared with aseptic joint revision with exchange of femoral and acetabular components is still controversial due to the relative lack of medium- to long-term follow-up. Therefore, we analysed clinical and radiological outcomes of septic two-stage revisions compared with aseptic hip revision surgeries.

METHODS

In this retrospective study we assessed 82 consecutive patients who underwent two-stage revision for septic total hip (45 patients) or one-stage aseptic revision arthroplasty (37 patients). The average follow-up was 53 months for the aseptic group and 55 months for the septic group. For clinical evaluation, we used the Harris Hip Score (HHS) and the Merle d'Aubigné and Postel score. The postoperative pain level was determined with the visual analogue pain scale.

RESULTS

The surgeries were performed 124 months (aseptic group) and 119 months (septic group) after primary total hip arthroplasty on average. The main indications for aseptic revision surgeries were aseptic loosening (96%), dislocation (2.2%), and periprosthetic fracture (2.2%). In the clinical outcome patients achieved 75.5 points in the aseptic group and 73.4 points in the septic group in the Harris Hip Score. The Merle d'Aubigné and Postel Score revealed 12.5 points for the aseptic group and 13.1 points for the septic group. Mean level of persisting pain was 0.8 (aseptic group) and 0.4 (septic group) on the visual analogue scale (VAS). Overall survival in the aseptic group was 85.6% at 9.8 years 82.7% at 10.1 years for the septic group, with a repeat revision rate of 8.1% and 6.7%, respectively.

CONCLUSIONS

Performing aseptic acetabular and femoral revision hip arthroplasty showed equal clinical outcomes in relation to septic two-stage revision hip surgeries. Our results showed a tendency for better outcome in comparison with the information given in the literature for septic and nonseptic exchange arthroplasties, including a lower rate of re-revisions.