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

Short-term Comparison of Survivorship and Functional Outcomes for Metaphyseal Cones with Short and Long Stems in Revision Total Knee Arthroplasty

Printed porous titanium metaphyseal cones have become a mainstay for managing bone loss in revision total knee arthroplasty (rTKA). A short or long stem is routinely used when implanting a cone to augment fixation and offload stresses. This retrospective analysis compared the short-term survivorships and functional outcomes for use of a short or long stem with a metaphyseal cone.A total of 179 cases using metaphyseal cones and stems with median follow-up of 1.95 years (interquartile range, 1.00-2.14) were compared based on stem type. There were 55 cases with long stem(s) and 124 cases with short stem(s). Cases with both long and short stems were excluded. Demographics, Kaplan-Meier survivorships, and preoperative and 1-year postoperative patient-reported outcome measures (PROMs; 2011 Knee Society Score [KSS] objective knee score, function, and satisfaction scores; EuroQol five-dimension scale; and Short Form Survey Physical Component Summary and Mental Component Summary scores) were compared using t-tests with a significance level of α = 0.05. There were no significant differences in body mass index (mean ± standard deviation) or sex (men [%]) between the short and long stem cohorts (32.3 ± 5.3, 36.3% and 31.5 ± 5.5, 38.2%, respectively; p > 0.05). Patients who had short stems were younger (65.9 ± 8.8 vs. 69.0 ± 9.4, p = 0.0323).Revision-free survivorship for the femoral or tibial component was 100% for long stems and 98.2% for short stems at 1 and 2 years, respectively (log-rank p = 0.6330). The two revisions in the short group were for infection, thus the survivorship for aseptic loosening was 100% at 2 years for both cohorts. There were no significant differences in preoperative or postoperative PROMs.This study demonstrated that highly porous printed metaphyseal cones provided rTKA with excellent early survivorship and similar PROMs whether a short or long stem was used. Additional studies will be needed to discern longer term differences.

Intraoperative and Postoperative Outcomes of Patients Undergoing Total Knee Arthroplasty With Prior Anterior Cruciate Ligament Reconstruction: A Matched Cohort Analysis

Background

Previous anterior cruciate ligament (ACL) injury is a risk factor for the development of knee osteoarthritis. Despite advances in ACL reconstruction (ACLR) techniques, many patients with history of ACLR develop end-stage osteoarthritis necessitating total knee arthroplasty (TKA). The purpose of this study was to investigate the impact of prior ACLR on intraoperative and postoperative outcomes of TKA.

Methods

This was a single-centre matched cohort study of all patients with prior ACLR undergoing primary TKA from January 2000 to May 2022. Patients were matched 1:1 to patients undergoing TKA with no prior ACL injury based on age, sex, and body mass index. Outcomes investigated included TKA procedure duration, soft-tissue releases, implant design, and complications requiring reoperation.

Results

Forty-two ACLR patients were identified and matched to controls. Mean follow-up was 6.8 years and 5.0 years in the ACLR and control cohorts, respectively (P = .115). ACLR patients demonstrated longer procedure durations (122.8 minutes vs 87.0 minutes, P < .001) and more frequently required soft-tissue releases (40.5% vs 14.3%, P = .007), stemmed implants (23.8% vs 4.8%, P = .013), and patellar resurfacing (59.5% vs 26.2%, P = .002). There were no significant differences in postoperative clinical or surgical outcomes between groups. Ten-year implant survivorship was 92% and 95% in the ACLR and control cohorts, respectively (P = .777).

Conclusions

TKA is an effective procedure for the management of end-stage osteoarthritis with prior ACLR. The care team should be prepared for longer operative times and the utilization of advanced techniques to achieve satisfactory soft-tissue balance and implant stability.

The Effect of Cemented Implants Placed During Initial TKA on Surgical Time and Expenses in Revision TKA

INTRODUCTION

Revision total knee arthroplasty (rTKA) is a complex procedure that often requires the removal of previous implants. There is little information evaluating the difference between removing cemented or noncemented knee prostheses in revision surgeries. The purpose of this study was to determine whether removing cemented or noncemented implants would affect surgical time and expenses incurred during revision procedures.

METHODS

This retrospective cohort study used a single-institution database to identify 300 patients who underwent femoral and tibial implant rTKA from 2016 to 2022 because of mechanical complications (infection cases excluded). Radiographs and surgical reports were used to confirm whether the fixation technique was cemented (N = 243) or noncemented (N = 57). The primary outcomes were surgical time and surgery costs. Secondary outcomes included readmission rates, revision implants used, stem usage, and insurance type.

RESULTS

The average surgical time was 121 minutes for noncemented and 128 minutes for cemented procedures (P = 0.118). The 90-day readmission rates for each group were similar at 7.00% for the cemented cohort and 8.77% for the noncemented cohort (P = 0.643). For patients with Medicare Advantage, the respective surgery costs were $1,966 for noncemented and $1,968 for cemented TKA (P = 0.988). For patients with commercial insurance, the respective surgery costs were $4,854 for noncemented and $5,660 for cemented TKA (P = 0.330).

CONCLUSION

Primary knee fixation type, cemented or noncemented, did not appear to influence the surgical duration or surgical costs of both-implant revision knee surgery indicated for mechanical complications.

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.

Clinical Outcomes of Offset Stem Couplers with or without Cone Augmentation in Revision Total Knee Arthroplasty

Intramedullary stems are often required in patients undergoing revision total knee arthroplasty (rTKA) to achieve stable fixation. Significant bone loss may require the addition of a metal cone to maximize fixation and osteointegration. The purpose of this study was to investigate clinical outcomes in rTKA using different fixation techniques. We conducted a single-institution retrospective review of all patients who received a tibial and femoral stem during rTKA between August 2011 and July 2021. Patients were separated into three cohorts based on fixation construct: press-fit stem with an offset coupler (OS), fully cemented straight (CS) stem, and press-fit straight (PFS) stem. A subanalysis of patients who received tibial cone augmentation was also conducted. A total of 358 patients who underwent rTKA were included in this study, of which 102 (28.5%) had a minimum 2-year follow-up and 25 (7.0%) had a minimum 5-year follow-up. In the primary analysis, 194 patients were included in the OS cohort, 72 in the CS cohort, and 92 in the PFS cohort. When stem type alone was considered, there was no significant difference in rerevision rate (p = 0.431) between cohorts. Subanalysis of patients who received augmentation with a tibial cone demonstrated that OS implants led to significantly higher rates of rerevision compared with the other two stem types (OS: 18.2% vs. CS: 2.1% vs. PFS: 11.1%; p = 0.037). The findings of the present analysis demonstrate that CS and cones in rTKA may provide more reliable long-term outcomes compared with press-fit stems with OS. LEVEL III EVIDENCE:  Retrospective Cohort Study.

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.

Radiolucent line assessment in cemented stemmed total knee (RISK) arthroplasty: validation of a modernized classification system

BACKGROUND

This study aims to implement and assess the inter- and intra-reliability of a modernized radiolucency assessment system; the Radiolucency In cemented Stemmed Knee (RISK) arthroplasty classification. Furthermore, we assessed the distribution of regions affected by radiolucency in patients undergoing stemmed cemented total knee arthroplasty.

METHODS

Stemmed total knee arthroplasty cases over 7-year period at a single institution were retrospectively identified and reviewed. The RISK classification system identifies five zones in the femur and five zones in the tibia in both the anteroposterior (AP) and lateral planes. Post-operative and follow-up radiographs were scored for radiolucency by four blinded reviewers at two distinct time points four weeks apart. Reliability was assessed using the kappa statistic. A heat map was generated to demonstrate the reported regions of radiolucency.

RESULTS

29 cases (63 radiographs) of stemmed total knee arthroplasty were examined radiographically using the RISK classification system. Intra-reliability (0.83) and Inter-reliability (0.80) scores were both consistent with a strong level of agreement using the kappa scoring system. Radiolucency was more commonly associated with the tibial component (76.6%) compared to the femoral component (23.3%), and the tibial anterior-posterior (AP) region 1 (medial plateau) was the most affected (14.9%).

CONCLUSION

The RISK classification system is a reliable assessment tool for evaluating radiolucency around stemmed total knee arthroplasty using defined zones on both AP and lateral radiographs. Zones of radiolucency identified in this study may be relevant to implant survival and corresponded well with zones of fixation, which may help inform future research.

Good Mid-Term Implant Survival of a Novel Single-Design Rotating-Hinge Total Knee Arthroplasty

BACKGROUND

Rotating-hinge knee (RHK) implants are an option for knee arthroplasty in cases of instability or severe bone loss. However, the revision rate can be increased compared to unconstrained implants which mandate improvements in implant design. This study investigates a novel RHK design for total knee arthroplasty (TKA).

METHODS

Retrospective analysis of a single design RHK TKA (GenuX MK, Implantcast) implanted between 2015 and 2019 including 133 patients (21 primary TKA, 112 revisions). The main indication for revision TKA was second-stage reimplantation following infection. The median follow-up amounted to 30 months (IQR 22-47).

RESULTS

In total, 13% (18/133) of patients underwent revision surgery after a mean time of 1 month (IQR 0-6). The main reason for the revision was (re-) infection in 8% of patients. All revisions were performed following revision TKA and none following primary TKA. There were no revision surgeries for loosening or instability. The revision-free implant survival of 83% was (95% CI 75-91%) after five years. A higher number of previous surgeries was associated with a greater revision risk (p = 0.05).

CONCLUSION

Revision and complex primary TKA using a single-design RHK implant results in good implant survival at mid-term follow-up although infection remains a major concern.

Long locking plate combined with locking attachment plate in patients with periprosthetic femoral fracture around ipsilateral stem after total knee arthroplasty

BACKGROUND

The purpose of this study was to introduce the surgical technique using long locking plate and locking attachment plate (LAP) in patient with periprosthetic femoral fracture around ipsilateral stem after total knee arthroplasty (TKA). Moreover, we sought to investigate the outcomes of this fixation technique and to propose a new subtype in the existing classification of periprosthetic femoral fractures.

METHODS

From January 2013 to January 2022, thirty-four consecutive periprosthetic femoral fractures around ipsilateral stem following TKA with minimum 1-year follow-up were enrolled in this study. Most cases were fixed with long-locking plate and LAP using the MIPO technique. For subgroup analysis, we classified patients with stemmed hip implant (group H) and stemmed knee implant (group K). Bone union, American Knee Society Score (AKSS) scale, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the Western Ontario and McMaster Universities Osteoarthritis Index for pain and function, and range of motion were investigated.

RESULTS

The number of group H and K were 24 patients (70.6%) and 10 patients (29.4%), respectively. The mean age at operation was 71.5 years (range, 65‒85 years), and the mean follow-up period was 27.5 months (range, 12‒72 months). Bone union was confirmed radiographically in all patients, and the mean union time was 4.9 months (range, 3.5‒6 months). There were no significant differences in radiographic and clinical outcomes between the groups.

CONCLUSIONS

Long-locking plate combined with LAP showed favorable radiographic and clinical outcomes in patients with periprosthetic femoral fracture around ipsilateral stem after TKA.

LEVEL OF EVIDENCE

Level IV, Retrospective Case Series.

Novel metaphyseal porous titanium cones allow favorable outcomes in revision total knee arthroplasty

INTRODUCTION

Loosening and migration are common modes of aseptic failure following complex revision total knee arthroplasty (rTKA). Metaphyseal cones allow surgeons to negotiate the loss of femoral and tibial bone stock while obtaining stable bony fixation. This study examines the mid-term functional and radiographic outcomes in patients undergoing rTKA utilizing a novel metaphyseal cone system with stems of variable length and fixation methods.

METHODS

This two-center retrospective study examined all patients who underwent rTKA with a novel porous, titanium tibial or femoral cone in combination with a stem of variable length and fixation who had a minimum follow-up of 2-years. Outcome analysis was separated into tibial and femoral cones as well as the stem fixation method (hybrid vs. fully cemented).

RESULTS

Overall, 123 patients who received 156 cone implants were included (74 [60.2%] tibial only, 16 [13.0%] femoral only, and 33 [26.8%] simultaneous tibial and femoral) with a mean follow-up of 2.76 ± 0.66 years. At 2-years of follow-up the total cohort demonstrated 94.3% freedom from all-cause re-revisions, 97.6% freedom from aseptic re-revisions, and 99.4% of radiographic cone osteointegration. All-cause revision rates did not differ between stem fixation techniques in both the tibial and femoral cone groups.

CONCLUSION

The use of a novel porous titanium femoral and tibial metaphyseal cones combined with stems in patients with moderate to severe bone defects undergoing complex revision total knee arthroplasty confers excellent results independent of stem fixation technique.

LEVEL OF EVIDENCE

IV, case series.

The impact of posterior-stabilized vs. constrained polyethylene liners in revision total knee arthroplasty

AIM

Posterior stabilized (PS) and varus valgus constrained (VVC) knee polyethylene liners have been shown to confer excellent long-term functional results following revision total knee arthroplasty (rTKA). The purpose of this study was to compare outcomes of patients who underwent rTKA using either a PS or VVC liner.

METHODS

A retrospective comparative study of 314 rTKA with either PS or VVC liner and a minimum follow-up time of two years was conducted. Patient demographics, complications, readmissions, and re-revision etiology and rates were compared between groups. Kaplan-Meier survivorship analysis was performed to estimate freedom from all-cause revision.

RESULTS

Hospital LOS (3.41 ± 2.49 vs. 3.34 ± 1.93 days, p = 0.793) and discharge disposition (p = 0.418) did not significantly differ between groups. At a mean follow-up of 3.55 ± 1.60 years, the proportion of patients undergoing re-revision did not significantly differ (19.1% vs. 18.7%, p = 0.929). In subgroup analysis of re-revision causes, the VVC cohort had superior survival from re-revision due to instability compared to the PS cohort (97.8% vs. 89.4%, p = 0.003). Freedom from re-revision due to aseptic loosening did not significantly differ between groups (85.2% vs. 78.8%, p = 0.436). Improvements in range of motion (ROM) from preoperative to latest follow-up were similar as well.

CONCLUSIONS

PS and VVC liners confer similar survivorship, complication rates, and overall knee ROM in rTKA. VVC liners were not associated with increased postoperative aseptic loosening and demonstrated superior freedom from re-revision due to instability. Future studies with longer follow-up are warranted to better determine significant differences in clinical outcomes between the two bearing options.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Preliminary outcomes following revision total knee arthroplasty using a new fixed-bearing revision knee system in Asians: a mean of 3-year follow-up

PURPOSE

The purpose of this study was to investigate the early outcomes of the new semi-constrained revision total knee arthroplasty (TKA) system by performing subgroup analysis according to the revision cause.

MATERIALS AND METHODS

From August 2019 to July 2020, 83 revision TKAs using the fixed-bearing Attune® revision knee system with a minimum follow-up of 2 years were retrospectively reviewed. Clinically, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the Western Ontario and McMaster Universities Osteoarthritis Index, and range of motion (ROM) were evaluated. The incidence of systemic and specific postoperative complications was investigated. Each cohort was divided into septic (group A, 34 patients) and aseptic mode (group B, 41 patients), and compared to assess the outcomes.

RESULTS

The mean age at the time of revision was 73.3 years (range 59.0 to 84.0 years), and the follow-up duration was 36.1 months (range 30.0 to 40.0 months). Clinical outcomes and ROM significantly improved at last follow-up (p < 0.001). Group A showed statistically inferior clinical outcomes in the last follow-up compared to group B. Four knees (5.3%) had a postoperative femoral joint line elevation of more than 5 mm. There were no serious systemic complications. One patient underwent re-revision TKA due to recurrence of infection. No stem tip impingement or cortical erosion was observed in all patients.

CONCLUSIONS

Revision TKAs using a new semi-constrained revision system showed favorable short-term follow-up outcomes, with improvement in clinical scores and ROM. Moreover, by using stem offsets, no postoperative stem tip impingement or cortical erosion was found.

LEVEL OF EVIDENCE

Level IV, Retrospective Case Series.

Bone loss in aseptic revision total knee arthroplasty: management and outcomes

Background

Although several techniques and implants have been developed to address bone loss in revision total knee arthroplasty (rTKA), management of these defects remains challenging. This review article discusses the indications and management options of bone loss following total knee arthroplasty based on preoperative workup and intraoperative findings.

Main text

Various imaging modalities are available that can be augmented with intraoperative examination to provide a clear classification of a bony defect. For this reason, the Anderson Orthopaedic Research Institute (AORI) classification is frequently used to guide treatment. The AORI provides a reliable system by which surgeons can classify lesions based on their size and involvement of surrounding structures. AORI type I defects are managed with cement with or without screws as well as impaction bone grafting. For AORI type IIA lesions, wedge or block augmentation is available. For large defects encompassing AORI type IIB and type III defects, bulk allografts, cones, sleeves, and megaprostheses can be used in conjunction with intramedullary stems.

Conclusions

Treatment of bone loss in rTKA continues to evolve as different techniques and approaches have been validated through short- and mid-term follow-up. Extensive preoperative planning with imaging, accurate intraoperative evaluation of the bone loss, and comprehensive understanding of all the implant options available for the bone loss are paramount to success.

Comparison of radiographic vs. computed tomography canal filling ratio measurement of stems in revision knee prostheses

Background

Lack of consensus on which measurement method gives the most accurate results for medullary canal filling ratio (CFR) of stems used in revision knee prostheses causes confusion when interpreting scientific studies. Therefore, the present study aims to find the most accurate measurement method of CFR on direct radiographs.

Methods

Twenty-eight femoral and 27 tibial components of 29 patients with a mean age of 72.86 ± 6.32 years were included in the study. Two different methods were used for computerized tomography CFR measurement. These methods and five different radiographic measurement methods used for CFR were compared statistically.

Results

There was no statistically significant difference between the real tomographic CFR of the femoral stem and the CFR calculation made by using ellipse area (p > 0.05). There was also no statistically significant difference between the tomographic CFR measurement calculated according to the largest stem size that can be implanted, and the method that accepted the smallest value as CFR after the measurement made according to Parsley's method on AP and lateral radiographs (p > 0.05). The results obtained by using all other tests were statistically different from each other.

Conclusion

CFR calculation made by using ellipse area, is the most accurate method for femoral stem CFR. The method that accepted the smallest value as CFR after the measurement made according to Parsley's method on AP and lateral radiographs is the most accurate method for tibial stem CFR.

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.

Tibial metaphyseal cones combined with short stems perform as well as long stems in revision total knee arthroplasty

Backgrounds

There is uncertainty around optimal tibial stem length in revision total knee arthroplasty (rTKA) utilizing a tibial trabecular metal (TM) cone. The purpose of this study was to compare: (1) functional outcomes, (2) radiographic outcomes and (3) implant survivorship in rTKA utilizing TM cones combined with either short stems (SS) or long stems (LS) at minimum 2 years follow‐up.

Methods

In this retrospective, multi‐centre study, patients undergoing rTKA utilizing a TM cone between 2008 and 2019 were included. Patients were divided into: SS group (no diaphyseal engagement), and LS group (diaphyseal engagement). All relevant clinical charts and post‐operative radiographs were examined. Oxford Knee Score (OKS) and EuroQol‐5D (EQ‐5D‐5L) data were collected at most recent follow‐up.

Results

In total, 44 patients were included: 18 in the SS group and 26 in the LS group. The mean time of follow‐up was 4.0 years. Failure free survival was 94.4% for the SS group and 92.3% for the LS group. All failures were for prosthetic joint infections managed with debridement, antibiotics, and implant retention. At most recent follow‐up, 3 patients demonstrated radiographic signs of lucency (1 SS 2 LS, P = 1) and the mean OKS were 37 ± 4 and 36 ± 6 (P = 0.73) in the SS and LS groups, respectively.

Conclusion

Tibial SS combined with TM cones performed as well as LS in rTKA at minimum 2 years follow‐up. A tibial SS in combination with a TM cone is a reliable technique to achieve stable and durable fixation in rTKA.

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.

Handheld computer-navigated constrained total knee arthroplasty for complex extra-articular deformities

INTRODUCTION

The present study aimed to assess the postoperative alignment and clinical outcomes of patients with complex extra-articular deformities (EADs) undergoing computer-assisted surgery (CAS) for constrained total knee arthroplasty (TKA) with modular stem extensions.

MATERIALS AND METHODS

From May 2015 to July 2018, ten patients with EADs scheduled for constrained TKA were enrolled retrospectively. The preoperative average deviation from neutral (= 180°) mechanical axis was 15.3° (range of coronal alignment: 150.9° varus-202.9° valgus). Alignment was assessed using an accelerometer-based handheld CAS system. On long-leg films, the positions of the components and possible stems were analysed and templated preoperatively. The average follow-up was 3.3 years (range: 2.0-4.6 years).

RESULTS

The postoperative mechanical axis was within ± 3.0° from neutral in nine patients. In all patients, the Knee Society score (KSS) and range of motion improved significantly. A constrained condylar and a rotating hinge prosthesis were used in five patients each. In eight patients, the 100-mm cementless stem that was preferred by the authors was found to be unusable for the femur or the tibia in the planning stage. For the femur, a cementless 100-mm stem was used in three, and a cemented 30-mm stem in five patients; a femoral stem was not usable in two patients. For the tibia, a cementless 100-mm stem was used in six, and a cemented 30-mm stem in two patients; a monoblock rotating hinge tibia was used in two patients.

CONCLUSIONS

Complex EADs were excellently managed during constrained TKA implantation using the handheld CAS system. Templating allowed the possible stem lengths to be identified and prevented anatomical conflict with the CAS-configured mechanical alignment. Limb alignment and function improved significantly after surgery. No intra- or postoperative complications occurred.

LEVEL OF EVIDENCE

Level IV, retrospective study.

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.

Comparison of the clinical and radiological outcomes between an isolated tibial component revision and total revision knee arthroplasty in aseptic loosening of an isolated tibial component

BACKGROUND

An isolated tibial component revision could be a treatment option for isolated tibial side loosening; however, few studies have proved its efficacy. This study aimed to compare the clinical and radiological outcomes between isolated (tibial component) and total (femoral and tibial component) revision total knee arthroplasty (TKA).

METHODS

Between January 2008 and February 2017, 31 patients underwent revision TKA for isolated tibial side loosening; 14 underwent an isolated tibial component revision (isolated group) and 17 underwent total (both femoral and tibial components) revision surgery (total group). The postoperative range of motion (ROM), Western Ontario and McMaster Universities osteoarthritis (WOMAC) index, Knee Society knee score (KSKS), Knee Society function score (KSFS), and mechanical axis (MA) were compared between the two groups. The intraoperative tourniquet time and amount of blood drainage were also compared.

RESULTS

The mean follow-up durations in the isolated and total groups were 40.7 and 56.1 months, respectively. Both groups had similar postoperative ROM, WOMAC index, KSKS, KSFS, and MA; however, significantly shorter tourniquet time (105.2 vs. 154.6 min, P < 0.001) and less blood drainage (417.2 vs. 968.1 ml, P < 0.001) were noted in the isolated group than in the total group.

CONCLUSION

Isolated tibial component revision TKA for tibial component loosening showed comparable clinical and radiological outcomes to those of total revision TKA. The advantages of the isolated tibial component revision surgery were short operation time and small blood loss.

STUDY DESIGN

Level III, Retrospective comparative study.

[End-of-stem pain in hip and knee arthroplasty]

End-of-stem pain after knee and hip arthroplasty with diaphyseal supportive stems is a frequently overlooked and potentially underestimated complication. A commonly recurring clinical phenome is the symptom-free interval after surgery of weeks to months, with new onset of symptoms under stress only later. The patient is often again reliant on walking sticks. End-of-stem pain is a diagnosis of exclusion. Pain is projected into the tip of the stem, and if differential diagnoses such as loosening are excluded, then the patient might be treated with a "bending-plate". Since bone cement has a similar elastic modulus to human cortical bone, a change of method to a cemented implant can also be expedient. In the primary situation, in addition to cemented stems, the use of "split-stems" could be useful. After revision surgery of any kind, a timely cessation of pain confirms the diagnosis.

Options and limitations of implant constraint

With an ever-increasing number of revisions, the surgeons will be faced with the dilemma of choosing the right implant for the revision knee. The soft tissue viability governs the choice of an implant at the time of revision. The selection ranges from the cruciate-retaining to the rotating/fixed hinge implants. The surgeon needs to plan preoperatively, but usually, the final decisions are made intraoperative. As determining the amount of constraint necessary can be challenging, we have tried to lay down a few pointers, which would help to make that choice. The posterior stabilized implants can manage most revision knees; in certain situations where they cannot accommodate the flexion-extension gap imbalance, a varus-valgus constrained implant should be used. The rotating hinge implants are used for severe instabilities or loss of soft tissue or bone around the knee. The use of a higher constraint implant has its consequences like reduced life span and reduced function. Thus it is crucial to use the least amount of constraint as necessary - however, as much as 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.

Postoperative alignment in revision total knee arthroplasty, a comparison between intra and extra-medullary tibial alignment

BACKGROUND

Revision total knee arthroplasty commonly involves stemmed components. If the diaphysis is engaged, this technique may be problematic for mechanical alignment (MA) in cases of tibial bowing, which are not infrequent (up to 30%). The aim of this study is to compare an intra-medullary(IM) and extra-medullary(EM) alignment method. We hypothesized that IM technique and canal-filling stems may result more frequently in valgus MA. On the other hand, an EM technique could produce less valgus knees but is at risk of creating MA outliers.

METHOD

A retrospective radiographic analysis of revision TKAs was performed. The patients were divided to either the EM or IM alignment group and compared on the overall post-operative MA. The following parameters were measured on standing, long leg x-rays: Hip-knee-Ankle angle (HKA), mechanical lateral distal femoral angle and mechanical medial proximal tibial angle (mMPTA).

RESULTS

119 cases of revision TKAs were included (EM = 80, IM = 39). There was a difference between the EM and IM group for the mean mMPTA (89.94° vs 90.92°, effect size = 0.45, p = 0.013) and HKA angle (1.64° vs 0.05°, effect size = 0.52, p = 0.0064). A higher proportion of IM patients were in overall valgus alignment (16/39, 41%) vs EM group (16/80, 20%, p = 0.0134). Both techniques showed the same proportion of outliers, defined as HKA angle more than 5 degrees from neutral mechanical alignment (11/80 vs 5/39, p = 0.286).

CONCLUSION

The extra-medullary alignment method with short cemented stems creates less valgus mechanical alignment than the intra-medullary technique with press-fit stems, without creating more MA outliers.

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.

Modified hybrid cementing technique reduces stem tip pain and improves patient's satisfaction after revision total knee arthroplasty

Background

There have been no studies comparing patient-reported outcome measures including end-of-stem tip pain and patient satisfaction based on the use of cementing techniques in revision total knee arthroplasty (TKA). The purpose of this study was to compare end-of-stem tip pain and PROMs with hybrid and modified hybrid cementing techniques in revision TKAs.

Method

Sixty-two cases of revision TKA performed by a single surgeon were divided into two groups based on the cementing technique with a minimum follow-up of 2 years. Two types of cementing technique for femoral and tibial stems were used as follows: (1) a hybrid cementing technique (33 cases), in which cement was applied immediately distal to the modular junction of the stem and the component while the distal stem was press-fitted into the diaphysis without using cement; and (2) a modified hybrid cementing technique (29 cases), in which cement was applied to the tip of femoral and tibial stems. The thigh and shin were assessed for the end-of-stem tip pain. Patient satisfaction was evaluated based on the satisfaction items of New Knee Society Score.

Results

Modified hybrid cementing significantly lowered the percentage of patients manifesting shin pain (3.4% vs. 24.2%, p = 0.029). Patients treated with the modified hybrid cementing technique showed a higher satisfaction rate (p = 0.003). Multivariate logistic regression analysis showed an increase in the odds of satisfaction 32.686-fold (p = 0.004) in patients without pain at the end-of-stem tip in the shin and 9.261-fold (p = 0.027) in patients treated with the modified hybrid cementing technique.

Conclusion

The modified hybrid cementing technique for fixation of long-stem in revision TKAs reduced the end-of-stem tip pain in the shin, leading to significantly higher satisfaction compared with the hybrid cementing technique after revision TKA.

Level of evidence

Level III

Clinical and radiological results of a stemmed medial pivot revision implant in aseptic total knee revision arthroplasty

BACKGROUND

Constraint choice in revision total knee arthroplasty depends on the stability of the collateral ligaments and on the severity of bone loss, but the least degree of constraint necessary is recommended. The purpose of this retrospective matched-paired study was to compare clinical results, radiographic outcome and the survival of a stemmed medial pivot revision implant in aseptic revision TKA vs. medial pivot implant in primary TKA.

METHODS

Records were reviewed for 69 cases of aseptic revision TKA using Advance® Medial Pivot Stemmed Revision Knee system between 2002 and 2016. These patients were then matched in a 1:2 ratio control group of patients who received a primary TKA with Advance® Medial Pivot system. American Knee Society Score and Visual Analogue Scale pain score were recorded. Alignment, loosening, and incidence of radiolucent lines were evaluated on X-rays. Implant survival was assessed by Kaplan-Meier survival analysis.

RESULTS

The primary TKA group had significant superior AKSS clinical and functional score at baseline (52.3 and 68.2 points, respectively) and at last follow up (84.6 and 68.6 points) compared with the revision TKA group (47.9 and 40.9 points; 78.4 and 59.9 points; P < 0.05). No significant difference was observed in the mean change from baseline to last follow up of AKSS score between the two groups (P > 0.05). Radiographical outcome and implant survival were similar in the two groups (P > 0.05).

CONCLUSION

The authors support the use of this revision system in knees with collateral ligaments competence and mild-to-moderate bone defect.

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.

The Role of Poly(Methyl Methacrylate) in Management of Bone Loss and Infection in Revision Total Knee Arthroplasty: A Review

Poly(methyl methacrylate) (PMMA) is widely used in joint arthroplasty to secure an implant to the host bone. Complications including fracture, bone loss and infection might cause failure of total knee arthroplasty (TKA), resulting in the need for revision total knee arthroplasty (rTKA). The goals of this paper are: (1) to identify the most common complications, outside of sepsis, arising from the application of PMMA following rTKA, (2) to discuss the current applications and drawbacks of employing PMMA in managing bone loss, (3) to review the role of PMMA in addressing bone infection following complications in rTKA. Papers published between 1970 to 2018 have been considered through searching in Springer, Google Scholar, IEEE Xplore, Engineering village, PubMed and weblinks. This review considers the use of PMMA as both a bone void filler and as a spacer material in two-stage revision. To manage bone loss, PMMA is widely used to fill peripheral bone defects whose depth is less than 5 mm and covers less than 50% of the bone surface. Treatment of bone infections with PMMA is mainly for two-stage rTKA where antibiotic-loaded PMMA is inserted as a spacer. This review also shows that using antibiotic-loaded PMMA might cause complications such as toxicity to surrounding tissue, incomplete antibiotic agent release from the PMMA, roughness and bacterial colonization on the surface of PMMA. Although PMMA is the only commercial bone cement used in rTKA, there are concerns associated with using PMMA following rTKA. More research and clinical studies are needed to address these complications.

Rotating Hinge Implants in Knee Arthroplasty

Due to demographic transition an increasing number of primary knee arthroplasty is expected. A consequence is a rise in frequency in revision knee arthroplasty. Rotating hinge prostheses are a development of former hinge prostheses, due to changes in implant design the outcome of modern rotating hinge implants clearly improved in comparison to former models. Interpretation of outcome in present literature is difficult due to the small number of cases and the heterogeneous indications. Nevertheless the use of rotating hinge knee prostheses in primary and revision arthroplasty is associated with good clinical outcomes, when indicated appropriately.

Central Sensitization Is a Risk Factor for Persistent Postoperative Pain and Dissatisfaction in Patients Undergoing Revision Total Knee Arthroplasty

BACKGROUND

The objective of this study is to investigate whether central sensitization (CS) was associated with patient dissatisfaction after revision total knee arthroplasty (TKA).

METHODS

Between 2012 and 2016, 68 cases (68 patients) of revision TKA performed by a single surgeon were included in this study with a minimum follow-up of 2 years. Patients were categorized into 2 groups by 40-point preoperative Central Sensitization Inventory (CSI) scores. The control group consisted of 48 patients (48 knees) with CSI scores of less than 40 points, while the CS group consisted of 20 patients (20 knees) with CSI scores of 40 points or more. Clinical outcomes were evaluated using an 11-point visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index scores. Patient satisfaction was evaluated using the satisfaction items of the new Knee Society Scores, where scores ≥20 indicated satisfaction.

RESULTS

Higher preoperative pain VAS scores in the CS group were maintained 3, 6, 12, and 24 months postoperatively (all P < .05). The CS group showed significantly worse pain, function subscores, and total scores of the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and at 2 years postoperatively. Forty-four (91.7%) patients in the control group and 3 (15.0%) patients in the CS group were satisfied with their revision TKAs (P < .001). Multivariate logistic regression analysis demonstrated that the odds of dissatisfaction after revision TKAs were increased 39.081 times (95% confidence interval 6.926-220.504, P < .001) in patients with CSI scores ≥40. Higher VAS intensity 2 years postoperatively also predicted dissatisfaction following revision TKA (odds ratio 1.864, 95% confidence interval 1.086-3.199, P = .024).

CONCLUSION

CS is a risk factor for persistent postoperative pain and dissatisfaction in patients undergoing revision TKAs.

LEVEL OF EVIDENCE

III.