No Difference in Implant Micromotion Between Hybrid Fixation and Fully Cemented Revision Total Knee Arthroplasty: A Randomized Controlled Trial with Radiostereometric Analysis of Patients with Mild-to-Moderate Bone Loss

Stem fixation techniques in revision total knee arthroplasty: A systematic review and meta-analysis

Purpose

This systematic review and meta-analysis aimed to compare the clinical and radiological outcomes of patients undergoing revision total knee arthroplasty (rTKA) using uncemented press-fit stems (hybrid fixation) versus cemented stems (cemented fixation). It is also examined whether cemented fixation offers any superiority over hybrid fixation regarding implant survival, clinical function, imaging analysis and complication rates.

Methods

Following the PRISMA guidelines, a systematic review and meta-analysis were conducted on five databases (Pubmed, Scopus, Embase, Medline and Cochrane). Articles were evaluated according to levels of evidence (LoE). Retrospective studies were analysed with risk of bias in nonrandomised studies of interventions (Robins-I) and randomised controlled trials with risk of bias 2 (RoB-2). This review was registered in the International Prospective Register of Systematic Reviews database. Meta-analysis was performed using R software, with p < 0.05 considered statistically significant.

Results

Data from 12 comparative studies with 1303 patients (1352 rTKAs) were analysed. Survival rates of hybrid and cemented fixations were comparable, with a significant trend favouring hybrid fixation (p = 0.04). Infection and aseptic loosening were the most common causes of failure. Radiographic failure rates showed no significant differences between fixation methods (p = 0.4). Meta-analysis indicated better results with hybrid fixation, although not statistically significant (KSS functional p = 0.15; KSS clinical p = 0.5). High heterogeneity was observed due to variations in patient characteristics and surgical strategies.

Conclusion

Both hybrid and cemented fixation techniques achieve satisfactory clinical results in rTKA, with hybrid fixation demonstrating an overall lower failure rate. The choice of fixation method must be tailored to individual patient characteristics and surgical considerations. Further high-quality randomised trials are needed to refine these results and optimise fixation strategies to improve patient outcomes.

Level of Evidence

Level IV.

Revision knee arthroplasty using a modular system manufactured in Brazil. Clinical and radiographic results with a mean nine-year follow-up

OBJECTIVE

To demonstrate the clinical and radiographic results of revision knee arthroplasty using a modular system manufactured in Brazil.

METHODS

Between November 2010 and January 2017, 31 revision knee arthroplasties were performed in 30 patients, using the MB-V system. Patients were assessed clinically and radiographically after a minimum follow-up of two years using the following scores: Knee Society Score (KSS), Knee Society Score ‒ Function (KSS ‒ Function), and Knee Society Roentgenographic Evaluation System (KSRES).

RESULTS

Among the patients, 19 were women. The mean age at surgery was 68 years. The mean follow-up was 9.1 years. There was no aseptic loosening in this period. The mean values of KSS, KSS-function, and KSRES were, respectively, 82, 77, and less than 4. One patient evolved with postoperative flexion instability. Two knees became infected, requiring the removal of the prosthesis and implantation of spacers loaded with antibiotics. One patient developed arthrofibrosis. One patient had a dislocation with full medial collateral avulsion and had to be re-operated with an insert exchange to a CCK liner and medial collateral reconstruction as proposed by Krakow.

CONCLUSION

This implant had 93.5 % survivorship (no cases of aseptic failure) and good results in 27 out of 31 knees (87 % of the surgeries).

Management of Bone Loss in Revision Total Knee Arthroplasty: An International Consensus Symposium

The evaluation, classification, and treatment of significant bone loss after total knee arthroplasty (TKA) continue to be a complex and debated topic in revision TKA (rTKA). Despite the introduction of new evidence and innovative technologies aimed at addressing the approach and care of severe bone loss in rTKA, there is no single document that systematically incorporates these newer surgical approaches. Therefore, a comprehensive review of the treatment of severe bone loss in rTKA is necessary. The Stavros Niarchos Foundation Complex Joint Reconstruction Center Hospital for Special Surgery, dedicated to clinical care and research primarily in revision hip and knee replacement, convened a Management of Bone Loss in Revision TKA symposium on June 24, 2022. At this meeting, the 42 international invited experts were divided into groups; each group was assigned to discuss questions related to 1 of the 4 topics: (1) assessing preoperative workup and imaging, anticipated bone loss, classification system, and implant surveillance; (2) achieving durable fixation in the setting of significant bone loss in revision TKA; (3) managing patellar bone loss and the extensor mechanism in cases of severe bone loss; and (4) considering the use of complex modular replacement systems: hinges, distal femoral, and proximal tibial replacements. Each group came to consensus, when possible, based on an extensive literature review and interactive discussion on their group topic. This document reviews each these 4 areas, the consensus of each group, and directions for future research.

A systematic review and meta-analysis of hybrid vs. cemented stems - which method is more optimal for revision total knee arthroplasty?

INTRODUCTION

The number of primary and revision Total Knee Arthroplasty (TKA) cases are expected to increase in future. There are various advantages and disadvantage to employing either of the two main types of stem fixation methods - cemented or hybrid technique. This review aimed to study the most optimal fixation method for revision TKAs by comparing radiological outcomes and re-revision rates.

METHODS

A systematic review and meta-analysis was performed using PubMed and Cochrane Library from 2010 to identify studies explicitly comparing outcomes between cemented against hybrid fixation revision TKA techniques, with a minimum follow up of at least 24 months. A total of 8 studies was included in this review. Egger's test and visual inspection of the funnel plot did not reveal publication bias.

RESULTS

There was no statistically significant difference in radiological failure and loosening (OR 0.79, CI 0.37-1.66, I2 = 29%, p = 0.22), all causes of re-revision (OR 1.03, CI 0.73-1.44, I2 = 0%, p = 0.56) and aseptic revision (OR 0.74, CI 0.27-2.02, I2 = 0%, p = 0.41) between cemented and hybrid techniques. Functional and pain outcomes compared between the two fixation techniques were largely similar across the studies included in this meta-analysis.

CONCLUSION

Despite a trend favouring hybrid stems in revision TKA, current evidence revealed that radiological outcomes and re-revision rates are largely similar between cemented and hybrid fixation techniques.

Midterm results of modular hinge total knee arthroplasty using cementless osseointegrating stems: low fixation associated complications and good functional outcome in primary and revision knee arthroplasty

PURPOSE

This study aimed to investigate functional outcome and complications after primary and revision modular H-TKA using hybrid fixation with cementless stems.

METHODS

Between 2015 and 2018, 48 patients with 50 implants were included after hybrid implantation of a single design H-TKA system using cementless osseointegrating stems and modular components. Complications and clinical outcome were analysed using Knee Society Score (KSS), the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) and the Short-Form Health Survey 12 (SF-12) score.

RESULTS

Indications for implantation were aseptic revision (n = 29, 58%), primary TKA (n = 19, 38%) and two-stage septic revisions (n = 2, 4%). Complications were reported in 26% (n = 12), whereas complications associated with hybrid fixation occurred in 5 (10%) cases, with 2 (4%) requiring revision surgery for aseptic loosening and 3 (6%) treated with an adapted postoperative protocol for perioperative fractures. Implant survivorship was 84% after a mean follow-up of 54 months. Postoperative KSS significantly improved from 51.50 (12-100) to 78.36 (41-99; p < 0.001). The mean WOMAC score was 19.26 (0-55), SF-12 PCS was 41.56 points (22.67-57.66) and SF-12 MCS was 49.21 points (23.87-63.21).

CONCLUSION

Hybrid modular implantation in H-TKA provides satisfactory clinical and functional results in primary and revision TKA. Clinical outcomes significantly improve with reduced pain, increased mobility, and good-to-excellent functional scores after implantation. Whilst implant survival is comparable to previous studies and complications associated with hybrid fixation are low, general complication rates are comparably high.

High Survivorship of Hybrid Fixation Technique in Aseptic Condylar Revision Total Knee Arthroplasty with Minimal Metaphyseal Bone Loss: 5-10 Year Clinical Outcomes

The aim of this study was to evaluate the outcomes of hybrid fixation technique in aseptic condylar revision total knee arthroplasty (rTKA). A retrospective consecutive study of patients with minimal metaphyseal bone loss who underwent aseptic rTKA with press-fit cementless femoral stems and short cemented tibial stems. Primary outcome measure was mechanical failure. Surgical complications, reoperations and revision for any cause were collected and Knee society score at final follow-up. Kaplan-Meier survival curves were used to estimate implant survivorship. Seventy-three patients were included with minimum 5 years follow-up with a mean age of 74.5 years. At mean follow-up of 8.5 years (range 5-10), only two patients required revision, both for infection. Radiographic evaluation was undertaken for all remaining patients at final follow-up and showed no evidence of mechanical failure. Six patients (8.4%) showed non-progressive radiolucent lines around the cementless femoral stem with only one having a pedestal at the tip of the femoral stem and four patients (5.6%) showed non-progressive radiolucent lines around the cemented tibial stem. Mean KSS score was 80.6 (standard deviation 13.8) indicating satisfactory clinical outcomes. Using "any cause implant revision" as an end point, implant survivorship for this construct was 97.3% at mean 8.5 years. In our experience, a hybrid fixation technique with a press-fit cementless femoral stem and a short-cemented tibial stemmed construct achieves excellent medium- to long-term outcomes in aseptic condylar revision cases with minimal metaphyseal bone loss.

Cemented versus Cementless Stem Fixation in Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

The number of revision knee arthroplasties (rTKA) is growing significantly as is the use of intramedullary stems for optimized stability. The choice of the most appropriate stem fixation method is still controversial. The purpose of this meta-analysis is to compare cemented versus cementless stem fixation in rTKA. Publications with patients undergoing rTKA with a follow-up > 24 months were systemically reviewed. Extracted parameters included total revision and failure rates for any reason, incidence of aseptic loosening, periprosthetic infection, and radiolucent lines, as well as the clinical outcome. A statistical regression analysis was then performed on all extracted clinical and radiological outcome data. A total of 35 publications met the inclusion criteria and were included and analyzed. Overall, 14/35 publications compared cementless versus cemented stem fixation, whereas 21/35 publications investigated only one stem fixation method. There were no significant differences in revision (p = 0.2613) or failure rates (p = 0.3559) and no differences in the incidence of aseptic loosening (p = 0.3999) or periprosthetic infection (p = 0.1010). The incidence of radiolucent lines was significantly higher in patients with cemented stems (26.2% versus 18.6%, p < 0.0001). However, no differences in clinical outcomes were observed. No superiority of a specific stem fixation method in rTKA was found. Rates of revision or failure for any reason as well as incidence of aseptic loosening and periprosthetic infection in cemented versus cementless stem fixation showed no significant difference. A higher incidence of radiolucent lines was observed in cemented stem fixation; however, no effect was observed on the clinical outcome.

A Systematic Review and Network Meta-Analysis of the Outcomes of Patients With Total Knee Arthroplasty Using Cemented, Uncemented, or Hybrid Techniques

In this study, we aim to explore the differences among the three types of fixation methods for the components of the knee joint in patients who underwent total knee arthroplasty (TKA). These methods are cemented, uncemented, and hybrid fixation. Cemented fixation means that a special type of grout is used to attach the components to the bone. Uncemented fixation means that the components are designed to fit tightly into the bone and allow new bone growth to secure them. Hybrid fixation means that a combination of cemented and uncemented fixation is used for different components. We searched four online databases to find studies relevant to our research question. We use the R program (R Foundation for Statistical Computing, Vienna, Austria) for network meta-analysis (NMA) to analyze the data from the studies. We calculate the mean difference (MD) and the 95% confidence interval (CI) for each outcome, which are statistical measures of the difference and the uncertainty between methods. We use these measures for continuous outcomes, meaning they can have any value. For dichotomous outcomes, meaning they can only have two values, we use the risk ratio (RR) and the 95% CI, which are statistical measures of the relative risk and the uncertainty between methods. We assess the quality of randomized controlled trials, which are studies that randomly assign participants to different methods, using the Cochrane Risk of Bias Assessment Tool 1, a tool that evaluates the potential biases in the studies. We include 21 studies, and our analysis shows that cemented TKA reveals a statistically significant decrease in pain with hybrid TKA (MD = -2.82). That said, we find no significant differences between uncemented and cemented or hybrid (MD = -0.80 and -2.02, respectively). The results show that there is no significant difference between uncemented TKA and cemented TKA or hybrid technique (RR = 0.87, 95% CI 0.35-2.14; RR = 0.73, 95% CI 0.22-2.39, respectively). Also, we find no significant difference between cemented TKA and hybrid TKA (RR = 0.84, 95% CI 0.24-2.93). Cemented TKA is associated with a lower risk of deep vein thrombosis (DVT) incidence rate. Moreover, it shows a significant decrease in pain compared to hybrid TKA. Future research is needed to compare among the three interventions.

Comparative Analysis of the Tibial Component Migration After Cemented and Uncemented Total Knee Arthroplasty with a Hydroxyapatite Coating in Two, Five, and Ten Years: A Meta-Analysis

Objective  This study evaluated and compared the tibial component migration in cemented and uncemented total knee arthroplasty (TKA) with no hydroxyapatite coating 2, 5, and 10 years after surgery. Methods  This meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) based on PubMed and MeSH database queries from June to July 2022. Results  The meta-analysis included eight randomized clinical studies evaluating 668 knees undergoing TKA. The maximum total point motion (MTPM) in cemented TKAs was higher in 5 years, with a mean value of 0.67 mm (95% confidence interval [CI], 0.52 to 0.87). Uncemented TKAs also presented higher mean MTPM in 5 years (1 mm; 95% CI, 0.82 to 1.22). Uncemented coated ATKs had a higher mean MTPM in 10 years (1.30 mm; 95% CI, 0.70 to 2.39). MTPM was statistically similar in the short- and long-term for cemented and uncemented techniques, with a standardized mean difference of -0.65 (95% CI, -1.65 to 0.35). Conclusion Tibial component migration in TKA was statistically similar at 2, 5, and 10 years in cemented and uncemented techniques, either with or without coating. However, due to the scarce literature, further studies are required with a longer follow-up time.

Acceptable migration of a fully cemented rotating hinge-type knee revision system measured in 20 patients with model-based RSA with a 2-year follow-up

BACKGROUND AND PURPOSE

Rotating hinged knee implants are highly constrained prostheses used in cases in which adequate stability is mandatory. Due to their constraint nature, multidirectional stresses are directed through the bone-cement-implant interface, which might affect fixation and survival. The goal of this study was to assess micromotion of a fully cemented rotating hinged implant using radiostereometric analysis (RSA).

PATIENTS AND METHODS

 20 patients requiring a fully cemented rotating hinge-type implant were included. RSA images were taken at baseline, 6 weeks, and 3, 6, 12, and 24 months postoperatively. Micromotion of femoral and tibial components referenced to markers in the bone was assessed with model-based RSA software, using implant CAD models. Total translation (TT), total rotation (TR), and maximal total point motion (MTPM) were calculated (median and range).

RESULTS

 At 2 years, TTfemur was 0.38 mm (0.15-1.5), TRfemur was 0.71° (0.37-2.2), TTtibia was 0.40 mm (0.08-0.66), TRtibia was 0.53° (0.30-2.4), MTPMfemur was 0.87 mm (0.54-2.8), and MTPMtibia was 0.66 mm (0.29-1.6). Femoral components showed more outliers (> 1 mm, > 1°) compared with tibial components.

CONCLUSION

Fixation of this fully cemented rotating hinge-type revision implant seems adequate in the first 2 years after surgery. Femoral components showed more outliers, in contrast to previous RSA studies on condylar revision total knee implants.

Fluoroscopic and radiostereometric analysis of a bicruciate-retaining versus a posterior cruciate-retaining total knee arthroplasty: a randomized controlled trial

AIMS

The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthroplasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinematics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA).

METHODS

A total of 40 patients with end-stage osteoarthritis were included in this randomized controlled trial. All patients performed a step-up and lunge task in front of a monoplane fluoroscope one year postoperatively. Femorotibial contact point (CP) locations were determined at every flexion angle and compared between the groups. RSA images were taken at baseline, six weeks, three, six, 12, and 24 months postoperatively. Clinical and functional outcomes were compared postoperatively for two years.

RESULTS

The BCR-TKA demonstrated a kinematic pattern comparable to the natural knee's screw-home mechanism in the step-up task. In the lunge task, the medial CP of the BCR-TKA was more anterior in the early flexion phase, while laterally the CP was more posterior during the entire movement cycle. The BCR-TKA group showed higher tibial migration. No differences were found for the clinical and functional outcomes.

CONCLUSION

The BCR-TKA shows a different kinematic pattern in early flexion/late extension compared to the CR-TKA. The difference between both implants is mostly visible in the flexion phase in which the anterior cruciate ligament is effective; however, both designs fail to fully replicate the motion of a natural knee. The higher migration of the BCR-TKA was concerning and highlights the importance of longer follow-up.Cite this article: Bone Joint J 2023;105-B(1):35-46.

No difference in long-term micromotion between fully cemented and hybrid fixation in revision total knee arthroplasty: a randomized controlled trial

AIMS

Both the femoral and tibial component are usually cemented at revision total knee arthroplasty (rTKA), while stems can be added with either cemented or press-fit (hybrid) fixation. The aim of this study was to compare the long-term stability of rTKA with cemented and press-fitted stems, using radiostereometric analysis (RSA).

METHODS

This is a follow-up of a randomized controlled trial, initially involving 32 patients, of whom 19 (nine cemented, ten hybrid) were available for follow-up ten years postoperatively, when further RSA measurements were made. Micromotion of the femoral and tibial components was assessed using model-based RSA software (RSAcore). The clinical outcome was evaluated using the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), and visual analogue scale (pain and satisfaction).

RESULTS

The median total femoral translation and rotation at ten years were 0.39 mm (interquartile range (IQR) 0.20 to 0.54) and 0.59° (IQR 0.46° to 0.73°) for the cemented group and 0.70 mm (IQR 0.15 to 0.77) and 0.78° (IQR 0.47° to 1.43°) for the hybrid group. For the tibial components this was 0.38 mm (IQR 0.33 to 0.85) and 0.98° (IQR 0.38° to 1.34°) for the cemented group and 0.42 mm (IQR 0.30 to 0.52) and 0.72° (IQR 0.62° to 0.82°) for the hybrid group. None of these values were significantly different between the two groups and there were no significant differences between the clinical scores in the two groups at this time. There was only one re-revision, in the hybrid group, for infection and not for aseptic loosening.

CONCLUSION

These results show good long-term fixation with no difference in micromotion and clinical outcome between fully cemented and hybrid fixation in rTKA, which builds on earlier short- to mid-term results. The patients all had type I or II osseous defects, which may in part explain the good results. Cite this article: Bone Joint J 2022;104-B(7):875-883.

The Cost-Effectiveness of Tibial Metaphyseal Cones in Revision Total Knee Arthroplasty

BACKGROUND

The purpose of this study is to evaluate the cost-effectiveness of tibial cones in revision total knee arthroplasty.

METHODS

A Markov model was used for cost-effectiveness analysis. The average cone price was obtained from Orthopedic Network News. The average cone aseptic loosening rate was determined by literature review. Hospitalization costs and baseline re-revision rates were calculated using the PearlDiver Database.

RESULTS

The maximum cost-effective cone price varied from $3514 at age 40 to $648 at age 90, compared to the current average selling price of $4201. Cones became cost-effective with baseline aseptic loosening rates of 0.89% annually at age 40 to 4.38% annually at age 90, compared to the current average baseline loosening rate of 0.76% annually.

CONCLUSION

For the average patient, tibial cones are not cost-effective, but may become so at lower prices, in younger patients, or in patients at substantially increased risk of aseptic loosening.

Superior Survival of Fully Cemented Fixation Compared to Hybrid Fixation in a Single Design Rotating Hinge Knee Implant

BACKGROUND

Clinical observations revealed higher rates of aseptic loosening for hybrid fixated rotating hinge knee implants compared to fully cemented ones. We hypothesize that the use of a fully cemented fixation technique had a higher survival rate for aseptic loosening compared to a hybrid fixation technique in a rotating hinge knee implant.

METHODS

All procedures of patients who were treated with the RT-PLUS rotating hinge knee implant (Smith & Nephew, Memphis, TN) between 2010 and 2018 were included. Primary outcome was revision for aseptic loosening. Kaplan-Meier survivorship and Cox proportional hazard regression analysis were performed to calculate survival rates and hazard ratios.

RESULTS

A total of 275 hinge knee implants were placed in 269 patients (60 primary procedures, 215 revisions). Median follow-up was 7.3 ± 3.9 years. In total, 24 components (16 hybrid femur, 2 fully cemented femur, 6 hybrid tibia; all revision procedures) in 19 patients were revised for aseptic loosening. Kaplan-Meier survivorship analysis showed superior survival rates of fully cemented components (femur 97.1%; tibia 100%) compared to hybrid fixated components (femur 89.5%; tibia 95.9%) at the 10-year follow-up. Multivariate Cox hazard analysis showed a significantly higher risk of aseptic loosening for hybrid fixated components, a prior stemmed component and the femoral component.

CONCLUSION

Fully cemented fixation showed superior survival rates for aseptic loosening compared to hybrid fixation in a single design rotating hinge knee implant. A prior stemmed component appears to be a risk factor for aseptic loosening and the femoral component seems to be more prone to loosening.

High Survivorship of Short-Cemented Femoral Stems in Condylar Revision Total Knee Arthroplasty Without Significant Metaphyseal Bone Loss: Minimum 5-Year Follow-Up

BACKGROUND

We aimed to evaluate the outcomes of hybrid fixation technique in condylar revision total knee arthroplasty (rTKA) using cementless metaphyseal tibial sleeves and short-cemented femoral stems with a rotating platform articulation.

METHODS

Retrospective consecutive study of all condylar rTKAs with a cemented femoral stem between 2009 and 2016 was conducted. Patients were identified using a local prospective database and linkable data obtained from the National Joint Registry for rTKA. Demographic, clinical, and surgical data were collected from patients' electronic health records. The primary outcome measure was mechanical failure and implant survivorship using a nationally collected data, complications, re-operations, and "any-cause revision" were also recorded.

RESULTS

There were 72 consecutive patients (72 knees) with minimum 5-year follow-up: 33 (45.8%) females and 39 (54.2%) males with a median age of 70 years (range 47-88). The indication for revision surgery was aseptic loosening (n = 34, 47.2%), instability (n = 17, 23.6%), infection (n = 14, 19.5%) with 10 patients having 2-stage approach and 4 patients with single-stage approach, stiffness (n = 4, 5.6%), and malalignment (n = 3, 4.1%). At mean follow-up of 6.87 years (median 6.7; range 5-11.8), only 2 patients required revision for infection. Using "any-cause implant revision" as an end point, implant survivorship for this construct was 97.2% at median 6.7 years. To date, none of the femoral stems have been revised for mechanical failure.

CONCLUSION

In rTKA with good femoral condylar bone stock, we have shown excellent survivorship with a short-cemented femoral stem, in conjunction with a mobile-bearing and a tibial sleeve. This has the advantage of reducing the length of the revision construct of this complex surgery.

LEVEL OF EVIDENCE

Level IV.

Early Survivorship of Newly Designed Highly Porous Metaphyseal Tibial Cones in Revision Total Knee Arthroplasty

Background

Metaphyseal cones provide durable fixation in revision total knee arthroplasty (TKA). However, there is a paucity of data on the outcomes of a new porous cone design. As such, the goal of this study was to analyze the early survivorship in patients undergoing revision TKA with this cone.

Methods

We retrospectively reviewed 163 revision TKAs with a newly designed porous tibial cone from 2016 to 2018. Mean age was 67 years, and mean body mass index was 33 kg/m². Minimum follow-up duration was 2 years. Most patients were revised for aseptic loosening (46%), 2-stage periprosthetic joint infection (PJI) reimplantation (28%), or instability (15%). Most were varus-valgus constrained (65%) or hinged (32%) constructs. The majority had hybrid tibial stem fixation (74%). A multivariate Cox regression analysis was used to identify risk factors for reoperation.

Results

Survivorship free from re-revision for aseptic loosening, any nonmodular revision, and any reoperation was 100%, 96%, and 86% at 2 years, respectively. No patients were revised for aseptic loosening. Six (4%) tibial cones were removed for PJI, one of which was loose. There were 23 reoperations (14%), most commonly for PJI (10%). Multivariate analysis identified PJI reimplantation (hazard ratios [HR] = 4.2, P = .002), males (HR = 2.9, P = .02), and hinged constructs (HR = 2.7, P = .02) as significant risk factors for reoperation.

Conclusions

In a complex revision TKA cohort with a new highly porous tibial cone, in which most patients received hybrid stem fixation and nonlinked and linked constraint, there was 100% survival free from re-revision for aseptic loosening at 2 years. Longer term follow-up is required.

The use of cement in revision total knee arthroplasty

Despite the availability of modern implants and techniques, Revision Total Knee Arthroplasty (R-TKA) still poses a challenge to surgeons, particularly the management of bone loss/defects and the secure fixation of implants. Polymethylmethacrylate (PMMA) bone cement plays an important role for fixation as fully uncemented fixation in RTKA is rarely used. Cement can be employed as part of a full cementing construct or as a hybrid construct. While in fully cemented implants, the diaphyseal stem as well as any couplers or connectors in the metaphysis are cemented, in hybrid cementing, only the component parts at the joint surface and metaphysis are cemented, while the diaphyseal stem is fixed in a press-fit manner. In this article the literature on the in vitro as well on the in vivo results of both fixation options is reviewed. Although the fixation mechanism of both constructs are different, radiographic and clinical survivorship appear similar for both techniques. Although there appears to be a trend towards a hybrid fixation method, the choice of which technique to employ in revision total knee arthroplasty will depend on the surgeons' familiarity with each technique as well as the factors peculiar to each patients anatomy.

Micromotion Analysis of Various Tibial Constructs in Moderate Tibial Defects in Revision Total Knee Arthroplasty

BACKGROUND

The purpose of this study is to compare the micromotion of various tibial reconstruction strategies including short cemented and long cementless stems with or without metaphyseal augmentation.

METHODS

A moderate tibial bone defect was milled into dual density polyurethane test blocks. Mechanical testing was performed on 4 test constructs: (1) short cemented stem (75-mm total length) alone; (2) short cemented stem with a symmetric metaphyseal cone; (3) a press-fit (175-mm total length) diaphyseal engaging tibial construct without a cone, and (4) the same press-fit tibial construct with a metaphyseal cone augment. Micromotion of the baseplate/cone construct with respect to the tibia block was measured during a stair descent loading profile for 10,000 cycles. The peak-to-peak micromotion of these various tibial constructs was compared. Unpaired t-tests were used to evaluate differences in peak-to-peak micromotion among the various tibial constructs tested. An analysis of variance was performed for final validation.

RESULTS

The cemented short stem demonstrated similar varus/valgus displacement, internal/external rotation, compression, and lift-off micromotion values under loading compared to a cementless long stem. A tibial cone improved compression and lift-off micromotion for both cemented and cementless constructs. A short 50-mm cemented stem with a cone demonstrated a lower micromotion at the anterior SI location compared to a press-fit 150-mm cementless stem without a tibial cone.

CONCLUSIONS

A short cemented tibial component with a cone achieved similar micromotion during simulated stair descent compared to a cementless diaphyseal press-fit implant in cases of moderate tibial defects.

Comparative Biomechanical In Vitro Study of Different Modular Total Knee Arthroplasty Revision Stems With Bone Defects

BACKGROUND

The aim of this study is to investigate the effects of different stem lengths and types including cones on primary stability in revision total knee arthroplasty with different femoral bone defects and fixation methods in order to maximize bone preservation. It is hypothesized that longer stems provide little additional mechanical stability.

METHODS

Thirty-five human femurs were investigated. A distal bone defect, Anderson Orthopedic Research Institute classification (s. 33) type-F2a, was created in group 1-3 and type-F3 in group 4-6. A cemented, rotating hinge femoral component was combined with different stems (100 and 160 mm total or hybrid cemented cones, or a 100-mm custom-made anatomical cone stem). The femora were loaded according to in vivo loading during gait. Relative movements were measured to investigate primary stability. Pull-out testing was used to obtain a parameter for the primary stability of the construct.

RESULTS

Relative movements were small and similar in all groups (<40 μm). For small defect, the pull-out forces of cemented long (4583 N) and short stems (4650 N) were similar and about twice as high as those of uncemented stems (2221 N). For large defects, short cemented stems with cones showed the highest pull-out forces (5500 N). Long uncemented stems (3324 N) and anatomical cone stems (3990 N) showed similar pull-out forces.

CONCLUSION

All tested stems showed small relative movements. Long cemented stems show no advantages to short cemented stems in small bone defects. The use of cones or an anatomical cone stem with hybrid cementation seems to offer good stability even for larger bone defects. The use of a short cemented stem (with or without cone) may be a suitable choice with a high potential for bone preservation in total knee arthroplasty revision with respective bone defects.

Hybrid stems are superior to cemented stems in revision total knee arthroplasty: a systematic review and meta-analysis of recent comparative studies

INTRODUCTION

The demand for revision total knee arthroplasty (TKA) has grown significantly in recent years. The two major fixation methods for stems in revision TKA include cemented and 'hybrid' fixation. We explore the optimal fixation method using data from recent, well-designed comparative studies.

METHODS

We performed a systematic review of comparative studies published within the last 10 years with a minimum follow-up of 24 months. To allow for missing data, a random-effects meta-analysis of all available cases was performed. The odds ratio (OR) for the relevant outcome was calculated with 95% confidence intervals. The effects of small studies were analyzed using a funnel plot, and asymmetry was assessed using Egger's test. The primary outcome measure was all-cause failure. Secondary outcome measures included all-cause revision, aseptic revision and radiographic failure.

RESULTS

There was a significantly lower failure rate for hybrid stems when compared to cemented stems (p = 0.006) (OR 0.61, 95% CI 0.42-0.87). Heterogeneity was 4.3% and insignificant (p = 0.39). There was a trend toward superior hybrid performance for all other outcome measures including all-cause re-revision, aseptic re-revision and radiographic failure.

CONCLUSION

Recent evidence suggests a significantly lower failure rate for hybrid stems in revision TKA. There is also a trend favoring the use of hybrid stems for all outcome variables assessed in this study. This is the first time a significant difference in outcome has been demonstrated through systematic review of these two modes of stem fixation. We therefore recommend the use, where possible, of hybrid stems in revision TKA.

Total knee arthroplasty with simultaneous tibial shaft osteotomy in patient with multiple hereditary osteochondromas and multiaxial limb deformity - a case report

BACKGROUND

Hereditary multiple osteochondromas (hereditary multiple exostoses, HME) is a rare genetic disease characterized by the development of benign osteocartilaginous tumors that may cause severe limb deformities and early onset osteoarthritis. Total knee arthroplasty (TKA) is the method of choice for the treatment of advanced gonarthrosis, however the surgical management with coexisting severe axial limb deformity remains unclear.

CASE PRESENTATION

65-year-old man with HME and extra-articular multi-axial limb deformity was admitted to the orthopedic department due to chronic knee pain and limited range of motion caused by secondary osteoarthritis. Regarding to the clinical and radiological examinations, after preoperative planning he was qualified to a one-stage TKA combined with tibial shaft osteotomy (TSO). In a one year follow-up full bone union was confirmed with no signs of implant loosening or prosthesis displacement. Patient was very satisfied, did not report any joint pain and has sufficient range of motion without knee instability.

CONCLUSION

The improvement of mechanical axis during TKA is a crucial factor for achieve operative success and long implant survival. Despite the higher risk of complication rate in comparison to two-stage treatment, one-stage TKA with simultaneous TSO should be a considerable method for patients with osteoarthritis and multiaxial limb deformities. This method can give a good clinical and functional outcomes, however should be performed subsequently to careful preoperative planning and proper patient qualification.

Influence of extension stem length and diameter on clinical and radiographic outcomes of revision total knee arthroplasty

BACKGROUND

Extension stems provide stability to revision total knee arthroplasty (RTKA). Little is known regarding the relationship between stem characteristics and RTKA stability. We aimed to identify the relationship between canal filling ratio (CFR) and aseptic loosening following RTKA.

METHODS

We retrospectively reviewed demographics, radiographic parameters, and outcomes associated with RTKA performed between 2008 and 2013 in a tertiary hospital. The inclusion criteria were: revision for aseptic loosening, hybrid fixation, minor bone defect, Zimmer® LCCK prosthesis, and follow-up > 24 months. Using the modified Knee Society radiographic scoring system, radiographic prosthesis loosening was defined as a radiolucent line (RLL) score ≥ 9 on the femoral side or ≥ 10 on the tibial side. We utilized receiver operating characteristic (ROC) curve analysis to evaluate the cutoff value for stem length and diameter in terms of prosthesis loosening or not. Furthermore, CFR-related parameters were analyzed with logistic regression to clarify their relationships with prosthesis loosening.

RESULTS

Prosthesis loosening was detected in 17 of 65 patients included. On logistic regression analysis, male sex and severity of the tibial bone defect were associated with loosening. On multivariate analysis, male sex and bone defect severity were associated with loosening on the femoral side, while malalignment was associated with loosening on the tibial side. Protective factors included femoral CFR > 0.85, CFR > 0.7 for > 2 cm, and CFR > 0.7 for > 4 cm, as well as tibial CFR > 0.85.

CONCLUSIONS

To minimize loosening post-RTKA, femoral CFR > 0.7 for > 2 cm and tibial CFR > 0.85 are recommended. Risk factors may include male sex, bone defect severity, and malalignment.

High precision and accuracy of model-based RSA for analysis of wrist arthroplasty

Radiostereometric analysis (RSA) is a method for measuring micromotion in joint arthroplasties. RSA has never been used in total wrist arthroplasties. We evaluated: (i) the precision of model-based RSA in total wrist arthroplasties measured in a phantom model and in patients; (ii) the number of bone markers necessary to ensure the precision; and (iii) the accuracy of model-based RSA in a phantom model. Reverse engineered models of radial and carpal/metacarpal components of two wrist arthroplasties (ReMotion® and Motec®) were obtained by laser scanning. Precision and accuracy of each arthroplasty were analyzed with regards to translation and rotation along the three coordinate axes. Precision was analyzed in 10 phantom and 30 clinical double examinations for each arthroplasty, and was expressed by a repeatability coefficient. The precision of different numbers and configurations of bone markers in the phantom model were compared. Accuracy was tested in a phantom model where the implants were attached to a micrometer, and was defined as the mean difference between measured and true migration. In the phantom model the precision for translations ranged from 0.03 to 0.14 mm and for rotations from 0.18 to 1.52°. In patients the precision for translations ranged from 0.06 to 0.18 mm, and for rotations from 0.32 to 2.18°. Less than four bone markers resulted in inferior precision. Accuracy ranged from -0.06 to 0.04 mm, and from -0.38 to -0.01°. Y-rotations could not be obtained from the Motec® due to rotational symmetry about the longitudinal axis. We conclude that model-based RSA in total wrist arthroplasties is precise, accurate, and feasible to use for clinical evaluation of micromotion in wrist arthroplasties. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3053-3063, 2018.

The Role of One-Stage Exchange for Prosthetic Joint Infection

PURPOSE OF REVIEW

In an era of increasing numbers of hip and knee replacements, strategies to manage prosthetic joint infection (PJI) that are effective at infection control with good patient-reported outcomes and cost containment for health systems are needed. Interest in single-stage exchange for PJI is rising and we assess evidence from the last 5 years related to this treatment strategy.

RECENT FINDINGS

Only five series for total knee replacement and ten series for total hip replacement have been reported in the last five years. More review articles and opinion pieces have been written. Reinfection rates in these recent studies range from 0 to 65%, but a meta-analysis and systematic review of all studies showed a reinfection rate of 7.6% (95% CI 3.4-13.1) and 8.8% (95% CI 7.2-10.6) for single-stage and two-stage revisions respectively. There is emerging evidence to support single-stage revision in the setting of significant bony deficiency and atypical PJIs such as fungal infections. Prospective randomised studies are recruiting and are necessary to guide the direction of single-stage revision selection criteria. The onus of surgical excellence in mechanical removal of implants, necrotic tissue, and biofilms lies with the arthroplasty surgeon and must remain the cornerstone of treatment. Single-stage revision may be considered the first-line treatment for all PJIs unless the organism is unknown, the patient is systemically septic, or there is a poor tissue envelope.

Stem Fixation in Revision Total Knee Arthroplasty: Indications, Stem Dimensions, and Fixation Methods

Although stems improve initial mechanical stability in revision total knee arthroplasty (TKA), ideal indications, proper lengths and diameters, and appropriate fixation methods remain controversial. The topics of the present article include the indications, selection of lengths and diameters, and fixation methods of stems in revision TKA. The use of a stem in revision TKA can protect the juxta-articular bone. A stem cannot be a substitute for optimal component fixation; it plays an adjunctive role in transferring the loads from the compromised metaphysis to the stronger diaphysis. Proper bone surface preparation and appropriate use of the stem based on a great store of knowledge are required to support the stemmed components effectively in revision TKA. The balance between overshielding and overloading the juxta-articular bone would provide excellent structural protection. The stem length and diameter should be tailored according to patients’ anatomical characteristics and determined fixation strategy. There are two traditional methods of stem fixation including the total cementation technique and the hybrid technique with a cementless press-fit stem. Selection of a cementation technique should be based on thorough consideration of advantages and disadvantages of each technique.

Revision total knee arthroplasty: hybrid vs standard cemented fixation

Introduction

Modular systems with stems are necessary for the stability of revision total knee arthroplasty (rTKA), but controversy remains as to the best fixation method: cemented or hybrid (noncemented stem). The aim of this study was to assess the clinical, X-ray, life-quality and survival results obtained with each fixation method.

Materials and methods

During the period 2000–2013, rTKA was performed on 67 patients (29 cemented arthroplasty and 38 hybrid fixation). The average follow-up was 7 years (range 2–15). All patients were evaluated clinically and radiographically using the American Knee Society Score (AKSS), the Western Ontario and McMaster Universities Arthritis Index (WOMAC), and the Short Form Health Survey (SF-36). A survival study was performed via Kaplan–Meier analysis.

Results

There were no differences between the cemented and hybrid fixation groups in the preoperative and postoperative AKSS clinical evaluation indices and the SF-36 health index. However, the WOMAC assessment scale did reveal statistically significant differences between the groups, with a global classification of 64.9 points weighted at 100 (SD 16.8) for cemented fixation versus 78.9 (SD 9.0) for hybrid fixation (p = 0.001). The corresponding values for stiffness were 61.6 (SD 12.9) and 80.5 (SD 14.7) (p = 0.001), and those for function were 61.3 (SD 19.4) and 78.1 (SD 10.5) (p = 0.001). No significant differences between the groups were recorded with respect to the pain score (p = 0.4) or the results of the Kaplan–Meier survival analysis.

Conclusion

Although the results were similar for the two groups, hybrid fixation tended to produce better results than cemented fixation. In view of the risk of further loosening, we prefer the more conservative approach, i.e. hybrid fixation.

Level evidence

Level III.

Antibiotic bone cement’s effect on infection rates in primary and revision total knee arthroplasties

AIM

To compare infection rates in primary and revision total knee arthroplasty (TKA) procedures using antibiotic impregnated bone cement (AIBC) to those rates in procedures not using AIBC.

METHODS

A systematic review and meta-analysis was conducted in search for randomized controlled trials/studies (RCTs) pertaining to the field of antibiotic AIBC vs non-AIBC groups in both primary and revision TKA procedures. The primary literature search performed was to identify all RCTs that assessed AIBC in primary and revision TKA procedures. This search was done strictly through the PubMed database using the article “filters” setting that identified and separated all RCTs from the overall search. The original search was “Primary/revision total knee arthroplasty using AIBC”. Other key terms and phrases were included in the search as well. Eligible articles that were used in the “results” of this review met the following criteria: (1) Involved primary or revision TKA procedures (for any reason); (2) included TKA outcome infection rate information; (3) analyzed an AIBC group vs a non-AIBC control group; (4) were found through the RCT filter or hand search in PubMed; and (5) published 1985-2017. Exclusion criteria was as follows: (1) Patients that were not undergoing primary or revision TKA procedures; (2) articles that did not separate total hip arthroplasity (THA) vs TKA results if both hip and knee revisions were evaluated; (3) papers that did not follow up on clinical outcomes of the procedure; (4) extrapolation of data was not possible given published results; (5) knee revisions not done on human patients; (6) studies that were strictly done on THAs; (7) articles that were not found through the RCT filter or through hand search in PubMed; (8) articles that did not evaluate AIBC used in a prosthesis or a spacer during revision; (9) articles that did not compare an AIBC group vs a non-AIBC control group; and (10) articles that were published before 1985.

RESULTS

In total, 11 articles were deemed eligible for this analysis. Nine of the 11 studies dealt with primary TKA procedures comparing AIBC to non-AIBC treatment. The other two studies dealt with revision TKA procedures that compared such groups. From these papers, 4092 TKA procedures were found. 3903 of these were primary TKAs, while 189 were revision TKAs. Of the 3903 primary TKAs, 1979 of these used some form of AIBC while 1924 were part of a non-AIBC control group. Of the 189 revision TKAs, 96 of these used some form of AIBC while 93 were part of a non-AIBC control group. Average follow-up times of 47.2 mo and 62.5 mo were found in primary and revision groups respectively. A two-tailed Fisher’s exact test was done to check if infection rates differed significantly between the groups. In the primary TKA group, a statistically significant difference between AIBC and non-AIBC groups was not found (AIBC infection rate = 23/1979, non-AIBC infection rate = 35/1924, P = 0.1132). In the revision TKA group, a statistically significant difference between the groups was found (AIBC infection rate = 0/96, non-AIBC infection rate = 7/93, P = 0.0062). No statistically significant differences existed in Knee Society Scores, Hospital for Special Surgery Scores, or Loosening Rates.

CONCLUSION

AIBC did not have a significant effect on primary TKA infection rates. AIBC did have a significant effect on revision TKA infection rates.

Tapered modular fluted titanium stems for femoral fixation in revision total knee arthroplasty

Consensus regarding femoral stem fixation options in revision total knee arthroplasty remains controversial. Tapered, modular, fluted titanium (TMFT) stems have an excellent track record in total hip arthroplasty for their ability to provide axial and rotational stability in situations of compromised host bone. We present 3 successfully treated cases in which the Food & Drug Administration granted permission to use custom TMFT stems in situations of failed femoral fixation in multiple revised knees. These stems hold promise to achieve stable fixation in revision total knee arthroplasty where host metadiaphyseal bone is deficient. Implant manufactures should consider dedicating future resources to create adapters that can link existing successful TMFT stems currently used in hip arthroplasty to revision total knee components when host bone is severely compromised.

Comparable Stability of Cemented vs Press-Fit Placed Stems in Revision Total Knee Arthroplasty With Mild to Moderate Bone Loss: 6.5-Year Results From a Randomized Controlled Trial With Radiostereometric Analysis

BACKGROUND

Short-term stability after revision total knee arthroplasty (TKA) with either fully cemented or hybrid-placed implants is comparable. Interestingly, implant micromotion >1 mm/degree occurred with both techniques which might increase the risk of loosening in the midterm or long-term. Therefore, the present study investigated midterm stability and clinical results of fully cemented vs hybrid-placed revision TKA, with mild to moderate bone loss, using radiostereometric analysis (RSA).

METHODS

This study involves the prolonged follow-up of a previous randomized controlled trial. RSA images taken at baseline, 6 weeks, 3 and 6 months, and 1, 2 and 6.5 years of follow-up were analyzed. Stability of the femoral and tibial implants was evaluated using total translation and rotation, based on the micromotion determined with model-based RSA.

RESULTS

Of the 30 patients who completed the 2-year follow-up in the original randomized controlled trial, 23 (12 cement, 11 hybrid) were available for follow-up at 6.5-year (range 5.4-7.3). There were no differences in median total translation and rotation of the femoral and tibial components between the 2 groups, and none of the clinical scores differed between the groups. Interestingly, in the group with cemented stems, 5 tibia implants showed >1 mm/degree micromotion compared to none in the hybrid group.

CONCLUSION

There was no difference in median micromotion and clinical outcome between fully cemented and hybrid-placed revision TKA 6.5 years postoperatively. Two femur components showed progressive migration over time whereas tibia components migrate especially in the first year followed by a stable situation. Whether this will lead to loosening and re-revisions remains to be investigated.