Debridement, Antibiotics and Implant Retention: A Systematic Review of Strategies for Treatment of Early Infections after Revision Total Knee Arthroplasty.

GOAL: The purpose of this review is to provide a systematic and comprehensive overview of the available literature on the treatment of an early prosthetic joint infection (PJI) after revision total knee arthroplasty (TKA) and provide treatment guidelines. METHODS: This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The search was conducted using the electronic databases of PubMed, Trip, Cochrane, Embase, LILACS and SciElo. After the inclusion of the relevant articles, we extracted the data and results to compose a treatment algorithm for early and acute PJI after revision TKA. RESULTS: After applying the in- and exclusion criteria, seven articles were included in this systematic review focusing on debridement, antibiotics and implant retention (DAIR) for PJI following revision TKA, of which one was prospective and six were retrospective. All studies were qualified as level IV evidence. CONCLUSIONS: The current literature suggests that DAIR is a valid treatment option for early infections after revision TKA with success rates of 50-70%. Repeat DAIR shows success rates of around 50%. Further research should be aimed at predicting successful (repeat/two-stage) DAIRs in larger study populations, antibiotic regimes and the cost effectiveness of a second DAIR after revision TKA.

No Association Between Hospital Volume and Early Second Revision Rate in Revision Total Knee Arthroplasty in the Dutch Orthopaedic Register.

BACKGROUND: Revision knee arthroplasty (R-KA) is rising globally. Technical difficulty of R-KA varies from liner exchange to full revision. Centralization has been shown to reduce mortality and morbidity rates. The present study aimed to evaluate the association between hospital R-KA volume and overall second revision rate, as well as revision rate for different types of revision. METHODS: The R -KAs between 2010 and 2020 with available data on the primary KA in the Dutch Orthopaedic Arthroplasty Register were included. Minor revisions were excluded. Implant data and anonymous patient characteristics were obtained from the Dutch Orthopaedic Arthroplasty Register. Survival analyses and competing risk analysis were performed per volume category (≤12, 13 to 24, or ≥25 cases/year) at 1, 3, and 5 years following R-KA. There were 8,072 R-KA cases available. Median follow-up was 3.7 years (range 0 to 13.7 years). There were a total of 1,460 second revisions (18.1%) at the end of follow-up. RESULTS: There were no statistically significant differences between second revision rates of the three volume groups. Adjusted hazard ratio for second revision were 0.97 (Confidence Interval (CI) 0.86 to 1.11) for hospitals with 13 to 24 cases/year and 0.94 (CI 0.83 to 1.07) with ≥25 cases/year compared to low volume (≤12 cases/year). Type of revision did not influence second revision rate. CONCLUSION: Second revision rate of R-KA does not seem to be dependent on hospital volume or type of revision in the Netherlands. LEVEL OF EVIDENCE: Level IV, Observational registry study.

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.

The use of a standard-length conical tapered stem in hip revision arthroplasty to address Paprosky type I-II femoral defects: a prospective study of 87 patients.

INTRODUCTION: Low-grade femoral defects in revision total hip arthroplasty (rTHA) might be preferably treated with a primary implant. Almost no previous study reported the use of standard-length conical tapered (SLCT) stems in these cases. We analyzed a series of cases using a SLCT stem in rTHA with Paprosky type I-II femoral defects. The purpose of the study was to determine clinical and radiographic outcomes in this series of rTHA. MATERIALS AND METHODS: We prospectively followed 87 patients undergoing a femoral component rTHA: 53 Paprosky type I and 34 type II femoral defects. Patient-reported measures (Oxford Hip Score, EQ-5D, VAS pain during rest and activity) were administered at baseline, 1 and 2 years post-operatively. Radiographic subsidence overtime was scored. Kaplan-Meier curves were used to evaluate the subsidence over time, the complication-free survival, and the implant survivorship with reoperation and stem revision as endpoints. RESULTS: The mean follow-up was 72.5 (SD ± 23.9) months. All PROMs significatively improved over time. The average subsidence was 2.8 (SD ± 3.2), 3.6 (SD ± 4.4), and 4.0 (SD ± 4.9) mm at 4, 12, and 24 months respectively. 6 stems had subsidence > 10 mm. The survival without complication was 0.85 (95% CI 0.94-0.77), while the implant survival without reoperation was 0.83 (95% CI 0.95-0.72). The overall stem survival rate was 93.7% (95% CI 0.91-0.97) at 2 years. CONCLUSION: The use of a SLCT stem in rTHA with Paprosky type I-II femoral defects demonstrated good survival with low subsidence rates during the first 2 years after surgery. Surgeons should consider the use of this primary prosthesis as a potential treatment during stem revision in cases with limited femoral bone loss.

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.

Custom-made acetabular revision arthroplasty for pelvic discontinuity: Can we handle the challenge? : a prospective cohort study.

AIMS: The aim of this study was to assess the clinical and radiological results of patients who were revised using a custom-made triflange acetabular component (CTAC) for component loosening and pelvic discontinuity (PD) after previous total hip arthroplasty (THA). METHODS: Data were extracted from a single centre prospective database of patients with PD who were treated with a CTAC. Patients were included if they had a follow-up of two years. The Hip Disability and Osteoarthritis Outcome Score (HOOS), modified Oxford Hip Score (mOHS), EurQol EuroQoL five-dimension three-level (EQ-5D-3L) utility, and Numeric Rating Scale (NRS), including visual analogue score (VAS) for pain, were gathered at baseline, and at one- and two-year follow-up. Reasons for revision, and radiological and clinical complications were registered. Trends over time are described and tested for significance and clinical relevance. RESULTS: A total of 18 females with 22 CTACs who had a mean age of 73.5 years (SD 7.7) were included. A significant improvement was found in HOOS (p < 0.0001), mOHS (p < 0.0001), EQ-5D-3L utility (p = 0.003), EQ-5D-3L NRS (p = 0.013), VAS pain rest (p = 0.008), and VAS pain activity (p < 0.0001) between baseline and final follow-up. Minimal clinically important improvement in mOHS and the HOOS Physical Function Short Form (HOOS-PS) was observed in 16 patients (73%) and 14 patients (64%), respectively. Definite healing of the PD was observed in 19 hips (86%). Complications included six cases with broken screws (27%), four cases (18%) with bony fractures, and one case (4.5%) with sciatic nerve paresthesia. One patient with concurrent bilateral PD had revision surgery due to recurrent dislocations. No revision surgery was performed for screw failure or implant breakage. CONCLUSION: CTAC in patients with THA acetabular loosening and PD can result in stable constructs and significant improvement in functioning and health-related quality of life at two years' follow-up. Further follow-up is necessary to determine the mid- to long-term outcome.Cite this article: Bone Jt Open 2023;4(2):53-61.

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.

Mid term outcomes of a novel metaphyseal porous titanium cone in revision total knee arthroplasty.

Introduction: Bone loss is present in all revision total knee arthroplasties. Metaphyseal cones allow surgeons to negotiate 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 revision total knee arthroplasty (rTKA) utilizing a novel metaphyseal cone system. Methods: This multicenter retrospective study examined all patients who received a porous, titanium tibial or femoral cone at four academic urban tertiary care institutions and presented for a minimum two-year follow-up. Patient demographics, indications for revision surgery, knee range-of-motion (ROM), re-revision rates, radiographic measurements, bone defect per AORI classification, and implant osseointegration were evaluated according to the Knee Society total knee arthroplasty (TKA) radiographic evaluation system. Results: One-hundred and four patients received 128 cone implants (84 tibial, 44 femoral cones; 24 patients with simultaneous ipsilateral tibial and femoral cones; 104 rTKA) with mean follow-up of 32.75 ± 6.54 months. The pre-operative main revision indications were aseptic loosening 36 (34.61 %), periprosthetic infection (PJI) 23 (22.11 %) and instability 18 (17.3 %). Thirteen rTKA underwent re-revision surgery: 3 for acute PJI, 4 for chronic PJI, 5 for instability, and 1 for mechanical failure of a hinged system. At most recent radiographic follow-up available, all unrevised cones had evidence of osteointegration and no visible implant migration.All-cause re-operation free survivorship was 87.5 % (91/104), and all-cause cone implant survivorship was 96.09 % (123/128 cones) at 2-year follow-up. Conclusion: This study demonstrates excellent mid-term outcomes of a novel porous, titanium metaphyseal cone in patients with large bone defects undergoing complex revision TKA. Level of evidence: IV, case series.

Patient-reported outcome measures, complication rates, and re-revision rates are not associated with the indication for revision total hip arthroplasty : a prospective evaluation of 647 consecutive patients.

AIMS: The aim of this study was to explore the relationship between reason for revision total hip arthroplasty (rTHA) and outcomes in terms of patient-reported outcome measures (PROMs). METHODS: We reviewed a prospective cohort of 647 patients undergoing full or partial rTHA at a single high-volume centre with a minimum of two years' follow-up. The reasons for revision were classified as: infection; aseptic loosening; dislocation; structural failure; and painful THA for other reasons. PROMs (modified Oxford Hip Score (mOHS), EuroQol five-dimension three-level health questionnaire (EQ-5D-3L) score, and visual analogue scales for pain during rest and activity), complication rates, and failure rates were compared among the groups. RESULTS: The indication for revision influenced PROMs improvement over time. This finding mainly reflected preoperative differences between the groups, but diminished between the first and second postoperative years. Preoperatively, patients revised due to infection and aseptic loosening had a lower mOHS than patients with other indications for revision. Pain scores at baseline were highest in patients being revised for dislocation. Infection and aseptic loosening groups showed marked changes over time in both mOHS and EQ-5D-3L. Overall complications and re-revision rates were 35.4% and 9.7% respectively, with no differences between the groups (p = 0.351 and p = 0.470, respectively). CONCLUSION: Good outcomes were generally obtained regardless of the reason for revision, with patients having the poorest preoperative scores exhibiting the greatest improvement in PROMs. Furthermore, overall complication and reoperation rates were in line with previous reports and did not differ between different indications for rTHA. Cite this article: Bone Joint J 2022;104-B(7):859-866.

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.

Stay Short or Go Long in Revision Total Hip Arthroplasty With Paprosky Type II Femoral Defects: A Comparative Study With the Use of an Uncemented Distal Fixating Modular Stem and a Primary Monobloc Conical Stem With 5-Year Follow-Up.

BACKGROUND: In the revisions for Paprosky type II femoral defects, diaphyseal fixating femoral stems are commonly used. To preserve bone stock, the use of a shorter primary conical stem could be an adequate alternative. The objective of this study is to compare the results of a primary conical stem to the more commonly used diaphyseal fixating modular revision stem in revision total hip arthroplasty surgery with Paprosky type II femoral defects. METHODS: A total of 59 consecutive patients with Paprosky type II femoral defects from our prospective revision registry were included. Thirty patients who received a long distal fixating modular stem (Revision Stem, Lima Corporate) and 29 patients who received a primary conical short stem (Wagner Cone, Zimmer) were prospectively followed. Minimal follow-up time was 2 years for subsidence and patient-reported outcome measures and 5 years for complications, reoperation, and revision. We compared subsidence, perioperative complications, reoperations, femoral component survival, Oxford Hip Score, EuroQol 5 Dimension, visual analog scale (VAS) for pain at rest, and VAS for pain during activity between stems. RESULTS: Both groups were comparable regarding demographic, clinical, and surgery-related characteristics. We found more perioperative complications and stem revisions with the modular revision stem than with the primary conical stem. There were no statistical differences in subsidence, EuroQol 5 Dimension, Oxford Hip Score, and VAS for pain at rest or during activity between both stems. CONCLUSION: In revision total hip arthroplasty with Paprosky type II femoral defects, uncemented primary monobloc conical femoral stems showed the same clinical result as distal fixating modular stems with fewer complications and fewer stem revisions.

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.

Good results at 2-year follow-up of a custom-made triflange acetabular component for large acetabular defects and pelvic discontinuity: a prospective case series of 50 hips.

Background and purpose - Custom triflange acetabular components (CTACs) are suggested as good solutions for large acetabular defects in revision total hip arthroplasty. However, high complication rates have been reported and most studies are of limited quality. This prospective study evaluates the performance of a CTAC in patients with large acetabular defects including pelvic discontinuity.Patients and methods - Prospectively collected data of 49 consecutive patients (50 hips), who underwent an acetabular revision with a CTAC were analyzed. Follow-up (FU) was 2 years. The median age of the patients was 68 years (41-89) and 41 were women. Primary outcomes were re-revision of the CTAC and differences between the modified Oxford Hip Score (mOHS) preoperatively and at 2-year follow-up. Secondary outcomes included several patient-reported outcomes (PROMs), radiological results, complications, and a comparison between hips with and without pelvic discontinuity (PD).Results - 1 patient (1 hip) was lost to the 2-year FU. No CTAC needed re-revision. The preoperative and 2-year FU mOHS were available in 40 hips and improved statistically significantly. All of the other secondary outcomes improved over time. 5 hips (of 45 with radiological 2-year FU) had loosening of screws. 8 hips had complications, including 3 persistent wound leakage, 3 pelvic fractures, and 1 dislocation. The mOHS and complication rate were similar in hips with and without PD.Interpretation - Reconstruction of large acetabular defects with and without PD with this CTAC showed good improvement in patient-reported daily functioning, high patient-reported satisfaction, few complications, and no re-revisions at 2-year FU.

Instability, an unforeseen diagnosis of the Legion™ hinge knee system.

BACKGROUND: Instability is an infrequently encountered diagnosis in rotating hinge knee (rHK) implants. With the introduction of a new rHK implant, we encountered multiple patients who complained of instability. This article presents its prevalence while describing our diagnostic and treatment algorithms. METHODS: A retrospective analysis of a cohort of all consecutive patients treated with the Legion™ Hinge Knee System (Smith&Nephew, Memphis, Tennessee) as primary or revision procedure between July 2014 and December 2018 was performed. All patients reporting a sense of instability or having recurrent joint effusion after activity were suspected of experiencing instability. Stress X-rays were performed and brace treatment was started. In patients with insufficient effect of brace treatment, a liner exchange to a thicker liner was performed. Prevalence of instability and the effect of treatment was analysed descriptively. RESULTS: In total, six patients were categorized as patients having instability problems (prevalence 3.5%; male:female ratio 5:1; median age 69.5 years; all revision procedures). Indication for revision to the Legion rHK implant was infection (three), instability (two) and aseptic loosening (one). In two patients, a prior rHK implant was revised. All patients showed tilting beyond the tolerance on stress X-ray examination. Brace treatment was adequate in three patients; in the other three patients a liner exchange was performed, two of which were satisfied. CONCLUSION: Instability is an infrequently encountered diagnosis in rHK implants. The design of the Legion rHK implant seems prone to this problem with a prevalence of 3.5%. If brace treatment is insufficient a liner exchange might be considered.

Late Onset Metallosis after Revision Total Knee Arthroplasty with Metal-Backed Patellar Component In Situ.

We describe a small case series with severe metallosis after revision total knee arthroplasty (TKA) due to metal-backed patellar component failure. Metallosis is a rare complication after TKA, which may cause systemic and local symptoms. In our cases, diagnosis of metallosis was supported by radiographic imaging and aseptic aspiration. Two of our 3 cases were successfully revised; in the remaining case surgery was not desired because of her poor general condition. Based on these cases, we recommend performing regular checkups in case of a metal-backed patellar component to detect metallosis in an early stage, to prevent extensive revision surgery. Moreover, we recommend applying a low threshold to revise a metal-backed patellar component because of the severe consequences of metallosis that might occur.

Reinfection and re-revision rates of 113 two-stage revisions in infected TKA.

Introduction: Two-stage revision is the most frequently performed revision procedure of a (suspected) periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). The reported results of this treatment show large variability between studies, ranging between 0 - 40 percent failure. The purposes of this study were to determine long term (1) reinfection rate, (2) re-revision rates for any reason, and (3) the reinfection rate of patients with positive cultures at reimplantation. Methods: We prospectively followed and retrospectively reviewed 113 consecutive two-stage revision TKAs, performed between 2003 and 2013 in our clinic with a minimum follow-up of 2 years. Diagnosis of PJI was based on the major Musculoskeletal Infection Society criteria for PJI. Results: After a mean follow-up of 94 months (range 24-172 months), infection recurred in 23 cases (23%). Of these, nine cases (9%) were defined as relapse (same micro-organism as index revision) and in 14 cases another causative was found (14%). In 11 patients debridement, antibiotics and retention of the prosthesis successfully eradicated the reinfection. After overall follow-up 17 patients (17%) underwent re-revision surgery, 11 patients (11%) due to an infection and 6 patients (6%) for aseptic reasons. Conclusions: Treatment of a (suspected) infection of a TKA by a two-stage revision had acceptable results based on re-revision and re-infection rates in the long term (>5 years), resembling the short-term results (<2 years). Focussing on the cultures at the index two-stage revision, episodes of relapse and new infections during follow-up were almost equally divided. Reinfection rates were higher in cases with positive cultures at reimplantation. Patients should be counselled appropriately in this particular situation.

Maximal flexion and patient outcomes after TKA, using a bicruciate-stabilizing design.

INTRODUCTION: Physiological motion after total knee arthroplasty (TKA) should result in a large range of motion, which would lead to good clinical outcomes. An adjusted design of a bicruciate-stabilizing TKA was developed to reproduce physiological motion. The aim of this study was to (1) investigate the maximal knee flexion of this knee system, 1 year post-operatively; (2) determine the clinical and functional improvement and compare the outcomes between patients with and without high maximal flexion; and (3) evaluate the adverse events. MATERIALS AND METHODS: In this prospective study, 62 patients with osteoarthritis received a bicruciate-stabilizing TKA. Maximum flexion was measured on a lateral X-ray pre- and post-operatively. Clinical and functional scores and the adverse events were reported up until 2 years after surgery. RESULTS: Pre-operatively, the median (range) maximal flexion was 131.5 (90-153)° and 1 year post-operatively, it was 130 (82-150)°. The results for the clinical scores showed an improvement between pre-operative values and post-operative values. The Kujala score and Knee Osteoarthritis Outcome Score (KOOS) symptoms, sport and quality of life score were better in patients with high maximal flexion (≥ 125°). Ten (serious) adverse device events were reported. CONCLUSIONS: In conclusion, the bicruciate-stabilizing TKA obtained a maximal flexion comparable to the flexion pre-operatively and resulted in good clinical and functional outcomes. Patients with high flexion ability seem to perform better on clinical and functional outcomes. Furthermore, the adjusted design of the bicruciate-stabilizing TKA reduced the number of adverse events. LEVEL OF EVIDENCE: Prospective cohort study, Level II.

Long-Term Outcome Following Revision Total Knee Arthroplasty is Associated With Indication for Revision.

BACKGROUND: There is limited information about long-term clinical outcomes following revision total knee arthroplasty (TKA) in relation to the indication for revision. Previously, a clear relation between indication for revision and clinical outcome was shown after 2 years. Present study evaluated (1) whether the reported association at 2 year remains present at 7.5 years, and (2) how clinical outcome at 7.5 years developed compared to baseline and 2-year follow-up, and (3) whether patients had additional adverse events. METHODS: A cohort of 129 patients with a total system revision TKA was selected. Range of motion, Visual Analog Scale for pain and satisfaction, and clinical and functional Knee Society Score were obtained preoperatively, at 3 months, 1, 2, and 7.5 years. Reasons for revision were septic loosening, aseptic loosening, malposition, instability, and severe stiffness. RESULTS: Patients revised for severe stiffness had significantly worse outcomes. No difference was found between the other indications. The clinical outcome after revision TKA at 7.5 years remained stable for septic and aseptic loosening, malposition, and instability but deteriorated slightly for the severe stiffness group. Visual Analog Scale satisfaction remained constant for all indications. There were 11 additional complications between 2- and 7.5-year follow-up, 9 of which necessitated reoperation. CONCLUSION: All indications except severe stiffness had a similar clinical outcome which was maintained up to 7.5-year follow-up. The severe stiffness group had worse outcomes and deteriorated slightly at longer follow-up. Outcome at 3 months seems predictive for long-term outcome. Additional complications did not differ significantly for the different reasons for revision. LEVEL OF EVIDENCE: Level III, prognostic study.

What Is the Reliability of a New Classification for Bone Defects in Revision TKA Based on Preoperative Radiographs?

BACKGROUND: Accurate quantification of bone loss facilitates preoperative planning and standardization for research purposes in patients who undergo revision TKA. The most commonly used classification to rate bone defects in this setting, the Anderson Orthopaedic Research Institute classification, does not quantify diaphyseal bone loss and reliability has not been well studied. QUESTIONS/PURPOSES: We developed a new classification scheme to rate bone defects in patients undergoing revision TKA and tested (1) the intraobserver and interobserver reliability of this classification for revision TKA based on preoperative radiographs, and (2) whether additional CT images might improve interobserver reliability. METHODS: This was a preregistered observational study. Interobserver reliability was analyzed using preoperative radiographs of 61 patients who underwent (repeat) revision TKA, and their bone defects were rated by five experienced orthopaedic surgeons. For intraobserver reliability, ratings were repeated at least 2 weeks after the first rating (Timepoints 1 and 2). Directly after the radiographic assessments of Timepoint 2, the observers were provided with CT images of each patient and asked to rate the bone defects for a third time (Timepoint 3), to assess the additional value of CT. Intraobserver and interobserver reliability were tested using Gwet's agreement coefficient 2, which is a measure of agreement between observers in categorical data. Substantial agreement was defined as coefficients between 0.61 to 0.8 and almost perfect agreement as > 0.8. RESULTS: The intraobserver reliability varied between 0.55 (95% CI 0.40 to 0.71) and 0.87 (95% CI 0.78 to 0.96) in the epiphysis, between 0.69 (95% CI 0.58 to 0.80) and 0.98 (95% CI 0.95 to 1) in the metaphysis, and between 0.95 (95% CI 0.90 to 0.99) and 0.99 (95% CI 0.98 to 1) in the diaphysis. The interobserver reliability varied between 0.48 (95% CI 0.39 to 0.57) and 0.49 (95% CI 0.42 to 0.56) in the epiphysis and between 0.81 (95% CI 0.75 to 0.87) and 0.88 (95% CI 0.83 to 0.93) in the metaphysis, and was 0.96 (95% CI 0.93 to 0.99) in the diaphysis at Timepoint 1. The interobserver reliability at Timepoint 2 was similar to that of Timepoint 1. The addition of CT images did not improve reliability (Timepoint 3). CONCLUSIONS: The bone defect classification was less reliable in the epiphyseal area compared with the metaphysis and diaphysis. This finding may be explained by prosthetic components obscuring this region or the more severe bone defects in this region. The addition of CT scans did not improve reliability. Further testing of reliability with observers from other institutions is necessary, as well as validity testing, by testing the classification in relation to intraoperative findings. LEVEL OF EVIDENCE: Level III, diagnostic study.

Improved clinical outcomes after revision arthroplasty with a hinged implant for severely stiff total knee arthroplasty.

PURPOSE: Management of the severely stiff total knee arthroplasty (TKA) is challenging, with the outcome of revision arthroplasty being inferior compared to the outcome for other indications. The aim of this study was to analyse the outcome after revision TKA with hinged-type implants for severely stiff TKA [range of motion (ROM) ≤ 70°] at 2 years. METHODS: A cohort of 38 patients with a hinged-type revision TKA (Waldemar Link or RT-Plus) and preoperative ROM ≤ 70° were selected from a prospectively collected database. ROM, visual analogue scale (VAS) for pain and satisfaction and Knee Society Score (KSS) were obtained preoperatively and at 3 months, 1 year and 2 years. Pre- and postoperative outcome were compared at 2 years. RESULTS: There was a significant increase in ROM and KSS. VAS pain scores did not differ significantly. The median ROM at 2 years was 90° (range 50°-125°) with a median gain of 45° (range 5°-105°). Median VAS pain was 28.5 (range 0-96) points and median VAS satisfaction was 72 (range 0-100) points at 2 years. Twelve patients suffered a complication. Recurrent stiff knee was the most frequently reported complication (n = 5). CONCLUSIONS: Hinged-type revision TKA following a severely stiff TKA renders a significant, although moderate, clinical improvement at 2 years. LEVEL OF EVIDENCE: Retrospective case series. Level IV.