The painful knee after TKA: a diagnostic algorithm for failure analysis

The Diagnostic Characteristic and Reproducibility of Bone Scintigraphy Single-Photon Emission Computed Tomography/Computed Tomography for Diagnosing Aseptic Loosening of Uncemented Total Knee Arthroplasty

BACKGROUND

The primary objective of this study was to investigate the diagnostic characteristics of bone scintigraphy single-photon emission computed tomography/computed tomography (BS-SPECT/CT) for diagnosing aseptic loosening after uncemented total knee arthroplasty (TKA), and to evaluate the following aspects: how to manage inconclusive results, the interobserver reliability, and the location of tracer uptake between symptomatic cases with and without aseptic loosening.

METHODS

In this study, 180 patients who had uncemented TKA and persistent knee pain suspected of aseptic loosening were included. As part of routine medical care, BS-SPECT/CT was used, and its results were compared with the reference standard, which involved revision surgery for aseptic loosening or a 12-month follow-up without revision or imaging. Inconclusive BS-SPECT/CT results were considered either negative (best-case scenario) or positive (worst-case scenario). Sensitivity, specificity, positive/negative likelihood ratios (LRs), and positive/negative predictive values (PPV and NPV) were calculated. Sensitivity analyses were conducted by comparing the diagnostic characteristics between cases with a follow-up of less and more than 2 years of follow-up. The anatomical distribution of tracer uptake and interobserver reliability were also evaluated.

RESULTS

Of the 180 BS-SPECT/CT scans conducted, 22 were determined positive, 113 negative, and 45 inconclusive. The best-case scenario showed a sensitivity of 66.7%, specificity of 93.8%, +LR 10.8, -LR 0.4, PPV 54.6%, and NPV 96.2%. In contrast, the worst-case scenario had a sensitivity of 94.4%, specificity of 69.1%, +LR 3.1, -LR 0.1, PPV 25.4%, and NPV 99.1%. Sensitivity analyses revealed no relevant differences in characteristics between the 2 TKA-interval groups. The interobserver reliability was fair-to-moderate (κ = 0.39; 95% confidence interval 0.18 to 0.60), with an estimated agreement of 79% (95% confidence interval 70 to 87). Four prosthetic zones had a notably higher proportion of cases with tracer uptake in those with aseptic loosening compared to those without.

CONCLUSIONS

The test characteristics of BS-SPECT/CT were deemed appropriate in patients who have complaints of uncemented TKA suspected of aseptic loosening. Inconclusive cases were best categorized as negative, especially in patients who have a short interval between TKA and the first BS-SPECT/CT. Increased tracer uptake in 4 prosthetic zones was observed in cases of aseptic loosening, although interobserver reliability was fair to moderate.

LEVEL OF EVIDENCE

Level III, Diagnostic Retrospective Cohort Study.

Advanced Imaging of Total Knee Arthroplasty

The prevalence of total knee arthroplasty (TKA) is increasing with the aging population. Although long-term results are satisfactory, suspected postoperative complications often require imaging with the implant in place. Advancements in computed tomography (CT), such as tin prefiltration, metal artifact reduction algorithms, dual-energy CT with virtual monoenergetic imaging postprocessing, and the application of cone-beam CT and photon-counting detector CT, allow a better depiction of the tissues adjacent to the metal. For magnetic resonance imaging (MRI), high bandwidth (BW) optimization, the combination of view angle tilting and high BW, as well as multispectral imaging techniques with multiacquisition variable-resonance image combination or slice encoding metal artifact correction, have significantly improved imaging around metal implants, turning MRI into a useful clinical tool for patients with suspected TKA complications.

Clinical Relevance of Posterior Osteophyte Formation in Ultra-congruent Total Knee Arthroplasty: Midterm Radiographic Rollback and Impingement Analysis

Background

Posterior femoral condylar osteophytes were frequently observed in patients with the ultra-congruent (UC) deep-dish design prosthesis. Therefore, the purpose of the present study was to verify the clinical relevance of osteophyte formation in the UC design.

Methods

From March 2014 to February 2018, a comparative study was conducted on 96 knees using the UC design. They were divided into 2 groups (group 1: osteophyte +, group 2: osteophyte -). Intraoperative findings, indirect femoral rollback assessment using 30° flexion and active full flexion lateral radiographs, serial change of the osteophyte, and outcomes were compared.

Results

The mean follow-up period was 49.35 ± 3.47 months in group 1 and 47.52 ± 3.37 months in group 2. Posterior component coverage was significantly different between the groups: group 1 exhibited more underhang and group 2 exhibited more overhang (p = 0.022). On the indirect assessment of the femoral rollback, there was a statistically significant difference in deep flexion and change in distance (p < 0.001 and p < 0.001, respectively). There was no statistical difference between the 2 groups in the American Knee Society knee and function score, and group 2 showed significant improvement in pain compared to group 1 in Western Ontario and McMaster University Arthritis Index pain score (p = 0.029).

Conclusions

Posterior condylar osteophyte formation was related to posterior impingement. It was more frequently observed in the underhang of the femoral component and insufficient femoral rollback. In addition, it changed with time and caused negative effects, including a gradual decrease in flexion and more pain.

Non-invasive quantitative assessment of induced component displacement can safely and accurately diagnose tibial component loosening in patients: A prospective diagnostic study

PURPOSE

Aseptic loosening often requires major, expensive and invasive revision surgery. Current diagnostic modalities merely show indirect signs of loosening. A recent proof of concept study proposed a non-invasive technique for the quantitative and visual assessment of implant movement as a diagnostic aid for tibial component loosening. The primary research question addressed is whether this novel diagnostic modality can safely and effectively aid the diagnosis of aseptic loosening.

METHODS

This clinical study included patients suspected of aseptic total knee arthroplasty (TKA) loosening listed for revision surgery and asymptomatic patients. Safety was evaluated using a numerical rating scale (NRS) for discomfort and by registration of adverse events. Feasibility was assessed by recording the duration and ease of the procedure. Intra- and interrater reliability were evaluated. In symptomatic patients, diagnostic accuracy metrics were evaluated with intra-operative assessment as a reference test.

RESULTS

In total, 34 symptomatic and 38 asymptomatic knees with a TKA were analysed. The median NRS for discomfort during loading was 6 (interquartile range [IQR]: 3.75-7.00) in symptomatic patients and 2 (IQR: 1.00-3.00) in asymptomatic patients. No adverse events were reported. The majority of users found the use of the loading device easy. The median time spent in the computed tomography room was 9 min (IQR: 8.00-11.00). Excellent to good intra- and interrater reliabilities were achieved. Diagnostic accuracy analysis resulted in a sensitivity of 0.91 (95% confidence interval [CI]: 0.72-0.97) and a specificity of 0.72 (95% CI: 0.43-0.90).

CONCLUSIONS

The proposed diagnostic method is safe, feasible, reliable and accurate in aiding the diagnosis of aseptic tibial component loosening.

LEVEL OF EVIDENCE

Level II.

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.

Investigation of the validity and reliability of the short physical performance battery in patients undergoing total knee arthroplasty

BACKGROUND

Practical, applicable, valid, and reliable tools are needed to assess physical performance in patients with Total Knee Arthroplasty (TKA) in a variety of settings, including routine clinical assessment, research studies, and community-based programs.

OBJECTIVE

The aim of this study is to evaluate the validity and reliability of the Short Physical Performance Battery (SPPB) among patients with TKA.

METHODS

We included 45 patients who underwent TKA surgery (mean age 68.89 ± 9.26). The SPPB, Timed up and go (TUG) test and, Hospital for Special Surgery (HSS) Knee Score were administered to the patients. SPPB was performed twice on the same day with 1 h rest.

RESULTS

The ICC(2,1) coefficient, MDC95 and SEM values were 0.97, 1.02 and 0.37 respectively. The Pearson correlation coefficient of the SPPB with the TUG and HSS was -.78, and 0.74 respectively.

CONCLUSION

SPPB has excellent reliability, and strong validity in assessing physical performance in patients with TKA. SPPB can identify even minimal detectable difference in physical performance and can be reliably used to monitor patient outcomes in the postoperative period for a comprehensive assessment of TKA in many physical performance domains, including balance, walking speed, and lower extremity strength.

CLINICAL TRIAL NUMBER

NCT06201637.

Only 26% of Native Knees Show an Identical Coronal Functional Knee Phenotype in the Contralateral Knee

BACKGROUND

A comprehensive exploration evaluating left-to-right knee symmetry across all anatomical planes utilizing three-dimensional (3D) scans stands absent from the existing body of research. Therefore, the primary objectives of this investigation involved examining potential differences and resemblances in alignment and structure between left and right non-osteoarthritic (native) knees in various planes (coronal, sagittal, and axial) using three-dimensional single-photon emission computed tomography/computed tomography (SPECT/CT) images.

METHODS

A total of 282 native knees from 141 patients were retrospectively gathered from the hospital's records. Patients, aged between 16 and 45, who underwent Tc99m-methyl diphosphonate SPECT/CT scans for both knees, adhering to the Imperial Knee Protocol, were included. A statistical analysis was conducted, including 23 knee morphometric parameters, comparing left and right knees, and classifying them based on functional knee phenotypes across the coronal, sagittal, and axial planes.

RESULTS

Regarding the functional coronal knee phenotype, 26% of patients (n = 37) exhibited identical phenotypes in both knees (p < 0.001). Significant correlated similarities between the left and right knees were observed in the coronal plane (Pearson's r = 0.76, 0.68, 0.76, 0.76, p < 0.001) and in several morphometric measures in the sagittal plane (Pearson's r = 0.92, 0.72, 0.64, p < 0.001). Moderately correlated similarities were noted in the axial plane (Pearson's r = 0.43, 0.44, 0.43, p < 0.001).

CONCLUSIONS

Only 26% of native knees exhibit an identical coronal phenotype in their contralateral knee, whereas 67% have the adjacent coronal phenotype. Strongly correlated resemblances were established across various left and right knee morphometric parameters in the coronal, sagittal, and axial planes. These findings could enhance decisions in procedures like total knee arthroplasties or osteotomies, where alignment is key to outcomes, and reveal a potential for future artificial intelligence-driven models to improve our understanding and improve personalized treatment strategies for knee osteoarthritis.

Load-induced deformation of the tibia and its effect on implant loosening detection

CT imaging under external valgus and varus loading conditions and consecutive image analysis can be used to detect tibial implant loosening after total knee arthroplasty. However, the applied load causes the tibia to deform, which could result in an overestimation of implant displacement. This research evaluates the extent of tibia deformation and its effect on measuring implant displacement. Ten cadaver specimen with TKA were CT-scanned under valgus/varus loading (20 Nm), first implanted without bone cement fixation (mimicking a loose implant) and subsequently with bone cement fixation (mimicking a fixed implant). By means of image analysis, three relative displacements were assessed: (1) between the proximal and distal tibia (measure of deformation), (2) between the implant and the whole tibia (including potential deformation effect) and (3) between the implant and the proximal tibia (reduced deformation effect). Relative displacements were quantified in terms of translations along, and rotations about the axes of a local coordinate system. As a measure of deformation, the proximal tibia moved relative to the distal tibia by, on average 1.27 mm (± 0.50 mm) and 0.64° (± 0.25°). Deformation caused an overestimation of implant displacement in the cemented implant. The implant displaced with respect to the whole tibia by 0.45 mm (± 0.22 mm) and 0.79° (± 0.38°). Relative to the proximal tibia, the implant moved by 0.23 mm (± 0.10 mm) and 0.62° (± 0.34°). The differentiation between loose and fixed implants improved when tibia deformation was compensated for by using the proximal tibia rather than the whole tibia.

Excellent mid- to long-term survival of tantalum metal cones in a case series of revision knee arthroplasty with severe bony defects

PURPOSE

Severe metaphyseal bone defects remain a challenge and represent a growing problem in revision total knee arthroplasty (RTKA). The purpose of this study was to examine the survival of first-generation tantalum metal cones (TMC) and to assess clinical and radiographic data obtained from mid- to long-term follow-ups (FU) after RTKA with severe bony defects.

METHODS

This retrospective case series included 100 consecutive patients of the same centre, who underwent RTKA surgery with TMC for tibia and/or femur bone defects between January 2011 and December 2015. Fourteen patients had died and six were lost for FU, leaving a total of eighty patients (one hundred and twelve TMC) for final evaluation. Clinical parameters including the Knee Society Score (KSS), visual analogue scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were determined preoperatively based on the patients' medical charts, and assessed again during the final FU after an average of 6.1 (5-9) years postoperative. Standardised postoperative X-rays were analysed during the final FU visit for osseointegration of the cones, and any signs of implant loosening were assessed with the modified Knee Society Radiographic review criteria. Perioperative and postoperative complications, reoperations, as well as implant and cone re-revisions were analysed. Survivorship analysis was performed with (a) cone-related revision for any reason and (b) implant component revision for any reason.

RESULTS

Previous RTKA had to be performed due to 64 (80%) aseptic and 16 (20%) septic failures. At the final FU, 75 (94%) tibia and 76 (95%) femur TMCs and implants were clinically stable. One patient experienced loosening of cones and implants at the femur and tibia but denied re-revision surgery. There were eight (10%) reoperations including two early wound healing problems, two inlay changes, two periprosthetic fractures, one debridement, antibiotics and implant retention (DAIR), and one secondary patella replacement. The six (7.5%) re-revisions included two aseptic loosening's of the opposite implant without TMC, one arthrodesis for recurrent instability, and three deep infections managed by two two-stage exchanges, and one amputation for persistent infection. At re-revision, all TMC cones were osteointegrated without signs of loosening. The determined clinical parameters showed significant (p < 0.001) postoperative improvement, and objective KSS was rated as excellent in 51%, and as good in 22% of patients at the final FU. The estimated 8-year Kaplan-Meier survival was 95% for TMC and 92.5% for implant components.

CONCLUSION

Tantalum metal cones (TMC) demonstrate a secure fixation for treatment of severe femoral and tibial metaphyseal bone defects during RTKA. This fixation concept showed excellent mid- to long-term clinical and radiographic outcomes with promising 8-year survival rates for cones and implant components.

LEVEL OF EVIDENCE

Retrospective cohort study, Level IV.

Robotic-assisted mechanically aligned total knee arthroplasty does not lead to better clinical and radiological outcomes when compared to conventional TKA: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Robotic-assisted total knee arthroplasty (R-TKA) has emerged as an alternative to improve the results of the conventional manual TKA (C-TKA). The aim of this study was to analyse the high-level studies comparing R-TKA and C-TKA in terms of clinical outcomes, radiological results, perioperative parameters, and complications.

METHODS

The literature search was conducted on three databases (PubMed, Cochrane, and Web of Science) on 1 February 2023 according to the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Inclusion criteria were: randomized controlled trials (RCTs), written in English language, published in the last 15 years, focusing on the comparison of C-TKA and R-TKA results. The quality of each article was assessed using the Cochrane risk-of-bias tool for randomized trials version 2 (RoB 2). The statistical analysis was carried out using random effects (DerSimonian & Laird) for weighted mean difference (MD) of the continuous variables and Peto method for odds ratios of the dichotomous variables.

RESULTS

Among the 2905 articles retrieved, 14 RCTs on 12 series of patients treated with mechanically aligned implants were included. A total of 2255 patients (25.1% males and 74.9% females; mean age 62.9 ± 3.0; mean BMI 28.1 ± 1.3) were analysed. The results of this systematic review and meta-analysis showed that R-TKA did not provide overall superior results compared to C-TKA in mechanically aligned implants in terms of clinical and radiological outcomes. R-TKA showed longer operative time (MD = 15.3 min, p = 0.004) and similar complication rates compared to C-TKA. A statistically significant difference in favour of R-TKA was found in the posterior-stabilized subgroup in terms of radiological outcomes (hip-knee-ankle angle MD = 1.7, p < 0.001) compared to C-TKA, although without resulting in appreciable difference of clinical outcomes.

CONCLUSION

R-TKA did not provide overall superior results compared to C-TKA in terms of clinical and radiological outcomes, showing longer operative time and similar complication rates.

LEVEL OF EVIDENCE

Level I.

The role of SPECT/CT in painful, noninfected knees after knee arthroplasty: a systematic review and meta-analysis-a diagnostic test accuracy review

PURPOSE

The aim of this systematic review was to present the current evidence on the clinical use of single-photon emission computed tomography/computed tomography (SPECT/CT) in the evaluation of noninfected painful knees after knee arthroplasty.

METHODS

Embase, PubMed, Google Scholar, Ovid, Scopus, Science Direct and the Cochrane Database of Systematic Reviews were searched from database inception to May 2022 following the PRISMA guidelines. As a primary outcome, we defined the role of SPECT/CT in the diagnostic approach to noninfected painful knee arthroplasty; as a secondary objective, we described the noninfection-related factors linked to painful knee arthroplasty. Pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio values and other indicators were calculated; receiver operating characteristic (ROC) curve analysis results and a summary of the areas under the curve (AUCs) from the included studies were reported. A Fagan plot, likelihood ratio plot and Deeks' funnel plot were generated and analysed. Methodological quality was assessed using the QUADAS-2 tool, and the certainty of evidence was assessed by the GRADE approach.

RESULTS

A total of 493 publications were identified, of which eight met the inclusion criteria, with a final pooled sample size of 308 patients. The pooled sensitivity and specificity of SPECT/CT in diagnosing the source of pain in painful knee prostheses were 0.86 (95% CI: 0.75-0.93) and 0.90 (95% CI: 0.79-0.96), respectively, with pooled +LR and -LR values of 8.9 (95% CI: 4.11-19.19) and 0.15 (95% CI: 0.09-0.28). The pooled diagnostic odds ratio was 57.35, and the area under the curve was 0.94. SPECT/CT highly accurately identified different sources of pain, such as loosening of the prosthetic components, patellofemoral overloading, instability, malalignment of the components and degeneration of the patellofemoral compartment. The confidence of the estimates was moderate according to the GRADE approach.

CONCLUSION

With demonstrated high sensitivity and specificity, as a diagnostic tool, SPECT/CT can identify the source of pain in painful knees after knee arthroplasty, particularly in cases of loosening, patellofemoral disorders and component malalignment (level of evidence III). These findings have significant clinical repercussions, such as in changing the initial diagnosis, identifying or excluding different causes of painful knee arthroplasties, guiding subsequent treatment and positively impacting the final clinical outcome. We moderately recommend the use of SPECT/CT for identifying the source of pain after knee arthroplasty according to the GRADE assessment. This review was preregistered in Prospero under code CRD42022320457.

Results of Robotic-Assisted Versus Manual Total Knee Arthroplasty at 2-Year Follow-up

Robotic-assisted technology has been developed to optimize the consistency and accuracy of bony cuts, implant placements, and knee alignments for total knee arthroplasty (TKA). With recently developed designs, there is a need for the reporting longer than initial patient outcomes. Therefore, the purpose of this study was to compare manual and robotic-assisted TKA at 2-year minimum for: (1) aseptic survivorship; (2) reduced Western Ontario and McMaster Universities Osteoarthritis Index (r-WOMAC) pain, physical function, and total scores; (3) surgical and medical complications; and (4) radiographic assessments for progressive radiolucencies. We compared 80 consecutive cementless robotic-assisted to 80 consecutive cementless manual TKAs. Patient preoperative r-WOMAC and demographics (e.g., age, sex, and body mass index) were not found to be statistically different. Surgical data and medical records were reviewed for aseptic survivorship, medical, and surgical complications. Patients were administered an r-WOMAC survey preoperatively and at 2-year postoperatively. Mean r-WOMAC pain, physical function, and total scores were tabulated and compared using Student's t-tests. Radiographs were reviewed serially throughout patient's postoperative follow-up. A p < 0.05 was considered significant. The aseptic failure rates were 1.25 and 5.0% for the robotic-assisted and manual cohorts, respectively. Patients in the robotic-assisted cohort had significantly improved 2-year postoperative r-WOMAC mean pain (1 ± 2 vs. 2 ± 3 points, p = 0.02), mean physical function (2 ± 3 vs. 4 ± 5 points, p = 0.009), and mean total scores (4 ± 5 vs, 6 ± 7 points, p = 0.009) compared with the manual TKA. Surgical and medical complications were similar in the two cohorts. Only one patient in the manual cohort had progressive radiolucencies on radiographic assessment. Robotic-assisted TKA patients demonstrated improved 2-year postoperative outcomes when compared with manual patients. Further studies could include multiple surgeons and centers to increase the generalizability of these results. The results of this study indicate that patients who undergo robotic-assisted TKA may have improved 2-year postoperative outcomes.

Preoperative Risk Factors of Persistent Pain following Total Knee Arthroplasty

Background

Despite good results of total knee arthroplasty (TKA) as a treatment of idiopathic osteoarthritis (OA) of the knee, significant number of patients (16-33%) complain of persistent pain of unknown origin. This phenomenon is the major cause of patient's dissatisfaction. It has been theorized that certain preoperative factors may increase the risk of persistent pain; hence, their identification should enable proper preoperative education and development of realistic expectations regarding results of TKA. This study is aimed at identifying the preoperative chronic pain predictors in patients undergoing TKA.

Methods

In this prospective cohort study, patients scheduled for TKA were examined one day prior to surgery. Demographics, comorbidities, pressure pain thresholds, pain intensity and duration, radiographic OA grade, and range of motion were recorded. Questionnaires such as Beck Depression Inventory (BDI) and Knee Injury and Osteoarthritis Outcome Score (KOOS) were collected. Study cohort was evaluated approximately 6 months following surgery. Patients were assigned to group A if they had no pain and to group B if they complained of any pain. Collected data was analyzed by biostatistician.

Results

64 patients were included in final analysis, 49 (76,6%) females and 15 (23,4%) males. Mean age was 67,6 yrs (48-84, ±7,42). Group A consisted of 21 patients (33%) while group B consisted of 43 patients (67%). There were no statistically significant differences regarding preoperative factors except for duration of preoperative pain, which was shorter in group A (36 (12-180) vs. 72 (24-180), p = 0,011). Every 12 months of preoperative pain were found to increase risk of persistent pain by 1,27 (p = 0,009).

Conclusions

Preoperative duration of pain is a risk factor for chronic pain following TKA. Therefore, patients should be operated on as soon as indications arise. Should the surgical treatment of knee arthritis be postponed, intensive and individualized pain management is highly recommended.

Zhuifeng tougu capsules inhibit the TLR4/MyD88/NF-κB signaling pathway and alleviate knee osteoarthritis: In vitro and in vivo experiments

Background: Knee osteoarthritis (KOA), a chronic degenerative disease, is mainly characterized by destruction of articular cartilage and inflammatory reactions. At present, there is a lack of economical and effective clinical treatment. Zhuifeng Tougu (ZFTG) capsules have been clinically approved for treatment of OA as they relieve joint pain and inflammatory manifestations. However, the mechanism of ZFTG in KOA remains unknown.

Purpose: This study aimed to investigate the effect of ZFTG on the TLR4/MyD88/NF-κB signaling pathway and its therapeutic effect on rabbits with KOA.

Study design:In vivo, we established a rabbit KOA model using the modified Videman method. In vitro, we treated chondrocytes with IL-1β to induce a pro-inflammatory phenotype and then intervened with different concentrations of ZFTG. Levels of IL-1β, IL-6, TNF-α, and IFN-γ were assessed with histological observations and ELISA data. The effect of ZFTG on the viability of chondrocytes was detected using a Cell Counting Kit-8 and flow cytometry. The protein and mRNA expressions of TLR2, TLR4, MyD88, and NF-κB were detected using Western blot and RT-qPCR and immunofluorescence observation of NF-κB p65 protein expression, respectively, to investigate the mechanism of ZFTG in inhibiting inflammatory injury of rabbit articular chondrocytes and alleviating cartilage degeneration.

Results: The TLR4/MyD88/NF-κB signaling pathway in rabbits with KOA was inhibited, and the levels of IL-1β, IL-6, TNF-α, and IFN-γ in blood and cell were significantly downregulated, consistent with histological results. Both the protein and mRNA expressions of TLR2, TLR4, MyD88, NF-κB, and NF-κB p65 proteins in that nucleus decreased in the ZFTG groups. Moreover, ZFTG promotes the survival of chondrocytes and inhibits the apoptosis of inflammatory chondrocytes.

Conclusion: ZFTG alleviates the degeneration of rabbit knee joint cartilage, inhibits the apoptosis of inflammatory chondrocytes, and promotes the survival of chondrocytes. The underlying mechanism may be inhibition of the TLR4/MyD88/NF-kB signaling pathway and secretion of inflammatory factors.

Diagnosis of Central Sensitization and Its Effects on Postoperative Outcomes following Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

Central sensitization (CS) has been extensively researched as a cause of persistent pain after total knee arthroplasty (TKA). This systematic review study sought to investigate the diagnosis of CS in patients who underwent TKA for knee osteoarthritis (OA) and the effect of CS on clinical outcomes after TKA. Three comprehensive databases, including MEDLINE, EMBASE, and the Cochrane Library, were searched for studies that evaluated the outcomes of TKA in knee OA patients with CS. Data extraction, risk of bias assessment, and (where appropriate) meta-analysis were performed. The standardized mean difference (SMD) with a 95% confidence interval was used to assess the different scales of pain. A total of eight studies were selected, including two retrospective studies and five prospective observational studies. One study used additional randomized controlled trial data. Five studies were finally included in the meta-analysis. All studies had a minimum follow-up period of 3 months. The Central Sensitization Inventory (CSI), whole-body pain diagram, and quantitative sensory testing (QST) were used for measuring CS. The pooled analysis showed that patients with CS had more severe postoperative pain after TKA (SMD, 0.65; 95% CI, 0.40−0.90; p < 0.01) with moderate heterogeneity (I2 = 60%). In patients who underwent TKA with knee OA, CSI is most often used for the diagnosis of CS, and the QST and whole-body pain diagram are also used. CS is closely associated with more severe and persistent pain after TKA.

Clinical radiographic outcomes and survivorship of medial pivot design total knee arthroplasty: a systematic review of the literature

BACKGROUND

Total knee arthroplasty is a reliable procedure able to reduce pain and disability in patients suffering from osteoarthritis. However, a considerable percentage of patients still experiences unsatisfactory results. Medial pivot total knee arthroplasty has been introduced in the clinical practice to overcome problems related with classic design implants and better mimic native knee kinematics. The aim of this study was to analyze survivorship and clinical and radiographic outcomes of medial pivot implants.

METHODS

A systematic research was conducted in eight different databases. Thirty-four studies met the inclusion criteria and were included in the analysis. Data on objective and patients-reported outcomes, radiographic alignment, and survivorship were collected and analyzed. Revision rate was expressed as revision per 100 components years.

RESULT

A total of 3377 procedures were included. Mean follow-up was 85.7 months (range, 12-182). The revision per 100 components years was 0.19, which corresponds to a revision rate of 1.9% after 10 years. Mean post-operative range of motion was 117.3 ± 0.4°. Mean clinical and functional Knee Society Score were, respectively, 85.9 ± 1.1 and 84.7 ± 3.5 at final follow-up. Post-operative femorotibial alignment was 177.1 ± 0.5°. Alfa and beta angles were 95.7 ± 0.1° and 89.2 ± 0.1°, respectively. Gamma and delta angles were 2.3 ± 0.6° and 86.7 ± 0.4°.

CONCLUSION

Medial pivoting implants provided excellent survivorship and low revision rate, as well as good-to-excellent results in term of objective and patient-reported clinical outcomes, and reliable correction of radiographic parameters. More high-quality studies with long-term follow-up are needed to clarify the role of medial pivoting implants.

Correlations of typical pain patterns with SPECT/CT findings in unhappy patients after total knee arthroplasty

PURPOSE

The diagnostic process in patients after painful total knee arthroplasty (TKA) is challenging. The more clinical and radiological information about a patient with pain after TKA is included in the assessment, the more reliable and sustainable the advice regarding TKA revision can be. The primary aim was to investigate the position of TKA components and evaluate bone tracer uptake (BTU) using pre-revision SPECT/CT and correlate these findings with previously published pain patterns in painful patients after TKA.

METHODS

A prospectively collected cohort of 83 painful primary TKA patients was retrospectively evaluated. All patients followed a standardized diagnostic algorithm including 99m-Tc-HDP-SPECT/CT, which led to a diagnosis indicating revision surgery. Pain character, location, dynamics and radiation were systematically assessed as well as TKA component position in 3D-CT. BTU was anatomically localized and quantified using a validated localization scheme. Component positioning and BTU were correlated with pain characteristics using non-parametric Spearman correlations (p < 0.05).

RESULTS

Based on Spearman's rho, significant correlations were found between pain and patients characteristics and SPECT/CT findings resulting in nine specific patterns. The most outstanding ones include: Pattern 1: More flexion in the femoral component correlated with tender/splitting pain and patella-related pathologies. Pattern 3: More varus in the femoral component correlated with dull/heavy and tingling/stinging pain during descending stairs, unloading and long sitting in patients with high BMI and unresurfaced patella. Pattern 6: More posterior slope in the tibial component correlated with constant pain.

CONCLUSION

The results of this study help to place component positioning in the overall context of the "painful knee arthroplasty" including specific pain patterns. The findings further differentiate the clinical picture of a painful TKA. Knowing these patterns enables a prediction of the cause of the pain to be made as early as possible in the diagnostic process before the state of pain becomes chronic.

LEVEL OF EVIDENCE

Level III.

A case report of ultrasound-guided knee nerve pulse radiofrequency combined with platelet-rich plasma in the treatment of knee osteoarthritis

RATIONABLE

Knee osteoarthritis (KOA) is a disease characterized by noninflammatory degenerative changes of articular cartilage. The main clinical manifestations are joint pain and stiffness. Pulsed radiofrequency (PRF) is thought to treat pain by destroying nerve tissue and changing the physical characteristics of nerve tissue membrane.

PATIENT CONCERNS

The patients presents with joint pain and tenderness. Touching around the knee joint will induce pain and joint stiffness when the hand is pressed hard.

INTERVENTIONS

Four patients with knee osteoarthritis underwent pulsed radiofrequency thermocoagulation in the knee joint cavity under ultrasound guidance and injected 2 mL of 10 mg/mL platelet-rich plasma into the joint cavity once a week for a total of 4 times. Record the patient's Visual Analogue Scale (VAS) score and the degree of knee movement limitation before treatment, 1, 3, and 6 months after treatment.

DIAGNOSES

Four patients with knee osteoarthritis.

OUTCOMES

After treatment, the patient's VAS score improved, and the knee joint mobility function recovered well. Ultrasound-guided knee nerve pulse radiofrequency combined with intra-articular injection of platelet-rich plasma can effectively improve the knee joint function and reduce the pain of the patient. The clinical effect is significant, and it is worthy of clinical application.

Management of instability after primary total knee arthroplasty: an evidence-based review

Background

Instability is one of the most common reasons for revision after a total knee replacement. It accounts for 17.4% of all single-stage revision procedures performed in the UK National Joint Registry. Through a careful patient evaluation, physical assessment and review of investigations one can identify the likely type of instability.

Aims

To critically examine the different types of instability, their presentation and evidence-based management options.

Method

A comprehensive literature search was conducted to identify articles relevant to the aetiology and management of instability in total knee replacements.

Results

Instability should be categorised as isolated or global and then, as flexion, mid-flexion, extension or recurvatum types. By identifying the aetiology of instability one can correctly restore balance and stability.

Conclusion

With careful judgement and meticulous surgical planning, instability can be addressed and revision surgery can provide patients with successful outcomes.

Diagnosis of Chronic Infection at Total Hip Arthroplasty Revision Is a Question of Definition

Purpose

Contradicting definitions of periprosthetic joint infection (PJI) are in use. Joint aspiration is performed before total hip arthroplasty (THA) revision. This study investigated the influence of PJI definition on PJI prevalence at THA revision. Test quality of prerevision aspiration was evaluated for the different PJI definitions.

Methods

256 THA revisions were retrospectively classified to be infected or not infected. Classification was performed according to the 4 different definitions proposed by the Musculoskeletal Infection Society (MSIS), the Infectious Diseases Society of America (IDSA), the International Consensus Meeting (ICM), and the European Bone and Joint Infection Society (EBJIS). Only chronic PJIs were included.

Results

PJI prevalence at revision significantly correlated with the applied PJI definition (p = 0.01, Cramer's V = 0.093). PJI prevalence was 20.7% for the MSIS, 25.4% for the ICM, 28.1% for the IDSA, and 32.0% for the EBJIS definition. For synovial fluid white blood cell count, the best ROC-AUC for predicting PJI was 0.953 in combination with the MSIS definition.

Conclusion

PJI definition significantly influences the rate of diagnosed PJIs at THA revision. Synovial fluid white blood cell count is a reliable means to rule out PJI. In cases with a borderline high synovial white blood cell count before THA revision as the only sign of chronic PJI, an extended diagnostic work-up should be considered.

Navigation und Robotik in der Knieendoprothetik

Hintergrund

Die Langlebigkeit einer Knieprothese hängt von der korrekten Ausrichtung der Prothesenkomponenten und der mechanischen Achse des Beins sowie einer optimalen Weichteilbalancierung ab. Um dieses Ziel präziser und sicherer zu erreichen, wurde die computerassistierte Chirurgie entwickelt. Ziel dieses Artikels ist es, die Navigation und Robotik zu bewerten und die aktuellen Ergebnisse zu diskutieren.

Methode

Umfassende Literaturrecherche in der Datenbank PubMed und dem Suchdienst Google Scholar.

Ergebnisse

Die computerassistierte Chirurgie führt zu einer präziseren Ausrichtung der mechanischen Beinachse und der Positionierung der Prothesenkomponenten. Trotzdem sind die klinischen Ergebnisse zur Kniefunktion und die Resultate der patientenbezogenen Fragebögen (PROMs) kontrovers. Sie zeigen, wie für die Überlebensrate, keinen signifikanten Unterschied zur konventionellen Technik. Hohe Anschaffungs- und Unterhaltskosten limitieren zudem die Verbreitung dieser Systeme.

Schlussfolgerung

Momentan bietet die bildgestützte Navigation dem Chirurgen bei gewissen Operationsschritten eine wertvolle Unterstützung für ein präziseres und sichereres Arbeiten. Trotzdem sind Langzeitstudien zur Kniefunktion, zu den PROMs, zur Überlebensrate dringend erforderlich. In der Robotik zeigen nur kurzfristige Ergebnisse ähnliche Trends wie bei der Navigation. Die Robotiksysteme müssen und werden sich weiterentwickeln, um den Anforderungen der Nutzer und Patienten zu entsprechen (Kosten, Größe, Programmierung).

Blood flow restriction exercise to attenuate postoperative loss of function after total knee replacement: a randomized pilot study

Aging well is directly associated with a healthy lifestyle. The focus of this paper is to relate that attenuation of postoperative loss of muscle function after a total knee arthroplasty (TKA) is an important consideration. Because patients usually do not tolerate standard high-resistance exercise in the preoperative or postoperative period, they often experience a decline in strength and function. Therefore, we tested the feasibility and acceptability of an alternative low-resistance exercise protocol with blood flow restriction (BFR) using a tourniquet in the preoperative period for patients awaiting TKA. We recruited patients undergoing a TKA and randomized six to the BFR exercise for 4 weeks prior to surgery and four to standard of care (no exercise). We measured physical function using the Short Physical Performance Battery (SPPB), the 6-Minute Walk Test (6MWT), leg strength (peak torque), and pain (numerical pain score) 4 to 5 weeks preoperatively and 2 weeks postoperatively. The clinical management, e.g., anesthetic management, did not differ between groups. No complications were observed. Our findings demonstrate the feasibility and acceptability of the BFR intervention. Although preliminary and not powered for comparison, the BFR group demonstrated less decline in SPPB following surgery (−2.2, 95%CI:−4.4,0.1) compared to the no exercise group (−4.8, 95%CI:−7.8,−1.7). No differences were noted for the 6MWT, leg strength, and pain measurements. We conclude that preoperative low-resistance exercise using the BFR is feasible and acceptable, and this test warrants investigation as an intervention to potentially attenuate the postoperative loss of physical function after TKA.

Nerve Growth Factor-Targeted Molecular Theranostics Based on Molybdenum Disulfide Nanosheet-Coated Gold Nanorods (MoS2-AuNR) for Osteoarthritis Pain

Osteoarthritis (OA) is a leading cause of chronic pain in the elderly worldwide. Yet current diagnosis and therapy for OA pain are subjective and nonspecific with significant adverse effects. Here, we introduced a theranostic nanoprobe based on molybdenum disulfide nanosheet-coated gold nanorods (MoS₂-AuNR) targeting never growth factor (NGF), a key player in pain sensation, for photoacoustic pain imaging and near-infrared (NIR) imaging-guided photothermal analgesic therapy. MoS₂ coating significantly improved the photoacoustic and photothermal performance of AuNR. Functionalization of MoS₂-AuNR nanoprobes by conjugating with NGF antibody enabled active targeting on painful OA knees in a surgical OA murine model. We observed that our functional nanoprobes accumulated in the OA knee rather than the contralateral intact one, and the amount was correlated with the severity of mechanical allodynia in our mouse model. Under imaging guidance, NIR-excited photothermal therapy could mitigate mechanical allodynia and walking imbalance behavior for both subacute and chronic stages of OA in a preclinical setting. This molecular theranostic approach enabled us to specifically localize the source of OA pain and efficiently block peripheral pain transmission.

Revision knee surgery: the practical approach

Revision total knee arthroplasty (rTKA) is a challenging procedure with often unreproducible results. A step-by-step approach is fundamental to achieving good outcomes.

Successful surgery requires a correct diagnosis of the original cause of failure. Only with an accurate and detailed plan can surgeons overcome difficulties presented in this scenario.

Any bone loss should be prevented during prosthetic component removal. Efficient tools must be chosen to avoid time-consuming manoeuvres.

Joint reconstruction based on a ‘dual-zone’ fixation is essential to provide a long-term survivorship of the implant. The use of relatively short fully cemented stems combined with a biological metaphyseal fixation is highly recommended by authors.

Flexion and extension gaps are accurately balanced after the establishment of the tibial platform.

Varus-valgus laxity is commonly managed with a condylar constrained prosthesis. If hinged implants are required, a stronger implant fixation is needed to counteract constraints forces.

Cite this article: EFORT Open Rev 2021;6:495-500. DOI: 10.1302/2058-5241.6.210018

Clinical and Radiological Outcomes after Knee Arthroplasty with Patient-Specific versus Off-the-Shelf Knee Implants: A Systematic Review

Customised, patient-specific implants (PSI) manufactured based on computed tomography data are intended to improve the clinical outcome by restoring more natural knee kinematics as well as providing a better fit and a more precise positioning. The aim of this systematic review is to investigate the effect of these PSI on the clinical and radiological outcome compared to standard, off-the-shelf (OTS) implants. Thirteen comparative studies including a total of 2127 knee implants were identified. No significant differences in clinical outcome assessed with the range of motion, the Knee Society Score (KSS), and the Forgotten Joint Score (FJS-12) were found between PSI and OTS implants. PSI showed fewer outliers from the neutral limb axis and a better implant fit and positioning. Whether these radiological differences lead to long-term advantages in terms of implant survival cannot be answered based on the current data. Patients receiving PSI could be discharged home earlier at the same or at an even lower total cost. The effective overall superiority of PSI has yet to be proven in long-term studies.

Typical Pain Patterns in Unhappy Patients After Total Knee Arthroplasty

BACKGROUND

The primary aim of this study is to assess characteristics of pain in patients with ongoing pain after total knee arthroplasty (TKA). The secondary aim of this study is to identify specific pain patterns and link these to underlying pathologies.

METHODS

A prospectively collected cohort of 97 painful primary TKA patients was retrospectively evaluated. All patients followed a standardized diagnostic algorithm, which led to a diagnosis that set the indication for revision surgery. Character, location, dynamics, and radiation of pain were systematically assessed and correlated with the underlying pathologies.

RESULTS

Most frequent pain characters were pricking/lancinating (45.7%), pinching/crushing, and dull/heavy (38.6%); 89.5% of all patients localized their knee pain anteriorly; 48.1% reported pain aggravations by descending stairs. Radiating pain was reported in 14% of the patients. Patella-related problems (56.7%) and instability (52.6%) were the most frequent pathologies. Based on correlations between the characteristics 6 specific pain patterns were identified. The most outstanding ones include the following: pattern 1, instability is associated with jumping/shooting, pricking/lancinating and tugging/wrenching pain, and aggravated by chair raising and starting; pattern 6, pain aggravation by descending stairs is associated with anterior and lateral jumping/shooting, tingling/stinging and sharp/lacerating pain character, and TKA positioning and patella baja.

CONCLUSION

The assessment of painful TKA patients involving specific pain patterns help to further differentiate and define the clinical picture and ultimately the cause of a painful TKA. If the causes of the described complaints are known, a decision for a therapy can be made reliably and sustainably at an early stage before the state of pain becomes chronic.

Assessing the feasibility of using the short physical performance battery to measure function in the immediate postoperative period after total knee replacement

Measurements of physical function after total knee arthroplasty (TKA) are uncertain and require investments for special equipment, space, and staff. Therefore, we evaluated the Short Physical Performance Battery (SPPB) 4 to 6 weeks preoperatively and 2 weeks following TKA as this test battery addresses lower extremity strength, coordination, and balance, without additional special investments. For context, we also employed the Six-Minute Walk test (6MWT) and peak torque knee extension. Our analysis consisted of three women and one man, with average ages of 68.3±3.9 years. Patients showed a decrease in all functional measurements: SPPB (mean change: -4.8±1.9, 44% decrease), 6MWT (-0.37±.21 m/s, 34% decrease), and peak torque (-11.8±8.8°/s, 68% decrease). Our findings suggest the SPPB is feasible and can be integrated easily in daily clinical practice.

Why do knees after total knee arthroplasty fail in different parts of the world?

OBJECTIVE

The aim of this narrative review was to provide an overview of failure modes after total knee arthroplasty in different parts of the world based on data from worldwide representative studies and National Joint Registries.

METHODS

A review of the available literature was performed using the keyword terms "total knee arthroplasty", "revision", "failure", "reasons", "causes", "complications", "epidemiology", "etiology"; "assessment", "painful knee", "registry" and "national" in several combinations. The following databases were assessed: Pubmed (https://pubmed.ncbi.nlm.nih.gov), Cochrane Reviews (https://www.cochrane.org), Google Scholar (https://scholar.google.com). In addition, registry data were obtained directly from national registry archives. Due to the heterogeneity of available data it was decided to present the review in a narrative manner.

RESULTS

Current literature report that infection has become the primary acute cause of TKA failure, while aseptic loosening and instability remain the overall most frequent reasons for revisions. Based on national registries certain tendencies can be deducted. The predominant overall failure mode of aseptic loosening is particularly found in Japan, United Kingdom, New Zealand and Switzerland. Leading early TKA failure mode represents infection with percentages of 20-30% in Sweden, Australia, New Zealand, Japan and the United States. Higher numbers could only be found in clinical studies on the Asian continent such as Korea (38%), China (53%), Iran (44%) and India (87%).

CONCLUSION

Although there are regional differences in TKA failure modes, TKA fails worldwide especially due to infections and aseptic loosening. It is important to diagnose these in good time and reliably using appropriate, standardized diagnostics in order to recommend the best possible therapy to the patient.

Customised, individually made total knee arthroplasty shows promising 1-year clinical and patient reported outcomes

INTRODUCTION

Customised individually made (CIM) implants for total knee arthroplasty (TKA) were introduced about 10 years ago. These implants aim to reduce the risk of prosthesis-related issues resulting from anthropometric differences between different knees. The purpose of this study was to analyse the short-term clinical outcome and patient reported outcome measures (PROMs) of a specific CIM implant, the ORIGIN^® knee replacement system (Symbios, Yverdon-les-Bains, Switzerland), which was introduced in 2018.

MATERIALS AND METHODS

This is a prospective cohort study of patients undergoing primary posterior-stabilised (PS) CIM TKA using the specific ORIGIN^® knee replacement system, (Symbios, Yverdon-les-Bains, Switzerland). TKAs were performed from February 2019 to October 2020. Data was collected preoperatively and postoperatively at 4 and 12 months. Outcome measures included the objective part of the Knee Society Score (KSS) with the range of motion (ROM) and the following PROMs: the Knee injury and Osteoarthritis Outcome Score (KOOS), the Forgotten Joint Score (FJS-12), the EuroQol, five dimensions, three levels (EQ-5D-3L) with the EuroQol visual analogue scale (EQ-VAS) and patient satisfaction. Differences in pre- to preoperative data were assessed with paired sample t tests. A p value < 0.05 was considered significant.

RESULTS

Twenty-five CIM TKA (20 patients, 8 female) were included. The mean age at surgery was 66 years (SD, 6.9). At 4 and 12 months, significant improvements in the KSS (p < 0.001), the ROM (p < 0.001), all KOOS subscales (p < 0.001), the FJS (p < 0.001) and the EQ-5D-3L (p < 0.026) were found. Satisfaction rate was 91% and 88% at 4 and 12 months, respectively. Intraoperative complications did not occur and no revision surgeries were undertaken.

CONCLUSIONS

The present study demonstrated significant improvements in the KSS and specific PROMs 1 year after CIM TKA. This study suggests that CIM TKA is a safe and suitable option, which can yield good clinical outcome and PROMs at least during short-term follow-up.

Reasons for failure in primary total knee arthroplasty - An analysis of prospectively collected registry data

Objective

The aim of this study was to determine the causes leading to a first revision of primary total knee arthroplasty (TKA) in a specialized knee centre and compare the results with previously published data.

Methods

Prospectively collected data of a consecutive number of 195 patients after primary TKA and who underwent first revision surgery after completing the diagnostic algorithm for persistent knee pain were included. Data was prospectively collected from a specialized knee centre in which the patients presented between 2015 and 2020 and retrospectively analysed. Indications for revision surgery were categorized using all available information from patients' records. Patients were divided into early (up to two years) and late revision (more than two years).

Results

Overall mean time from index to revision surgery was 3.6 years. 49% of knee revisions occurred in the first two years, 51% after two years. 86% of the patients were referred to the knee centre from other surgeons. The most frequent reason for revision was instability, followed by patellofemoral problems, extensor mechanism insufficiency and malalignment. The most frequently performed revision was complete removal and re-implantation of a semi constrained implant design (52.5%) followed by revision using a full constrained implant design (16%). Secondary patella-resurfacing as part of complete revision was carried out in 71.5% of the cases. The majority of the patients showed concurrent reasons for TKA failure with significant correlations amongst another. Furthermore, correlations were identified between indications for revision surgery and revision implant designs.

Conclusion

In a specialized knee centre the most common indications for the first TKA revision were instability and patellofemoral and/or extensor mechanism insufficiency followed by malalignment. In most patients there was not only one failure mode, but a combination of many. It is important to establish a standardized diagnostic algorithm to facilitate comprehensive and efficient diagnostics and the optimal treatment.

Literature review of the causes of pain following total knee replacement surgery: prosthesis, inflammation and arthrofibrosis

Adverse knee pain occurs in 10–34% of all total knee replacements (TKR), and 20% of TKR patients experience more pain post-operatively than pre-operatively. Knee pain is amongst the top five reasons for knee replacement revision in the United Kingdom. The number of TKRs is predicted to continue increasing due to the ageing population.

A narrative literature review was performed on the different causes of pain following TKR. A database search on Scopus, PubMed, and Google Scholar was conducted to look for articles related to TKR, pain, and cause. Articles were selected based on relevance, publication date, quality of research and validation. Relevant sections were added to the review.

One hundred and fourteen articles were identified and potential causes of TKR pain included: arthrofibrosis, aseptic loosening, avascular necrosis, central sensitization, component malpositioning, infection, instability, nerve damage, overstuffing, patellar maltracking, polyethylene wear, psychological factors and unresurfaced patella.

It is important to tailor our approach to address the individual causes of pain. Certain controllable risk factors can be managed pre-operatively to minimize post-operative pain. Risk factors help to predict adverse pain outcomes and identify specific causes.

There are multiple causes of pain following TKR. Some factors will require further extensive studies, and as pain is a commonly attributed reason for TKR revision, its underlying aetiologies should be explored. Understanding these factors helps to develop effective methods for diagnosis, prevention and management of TKR pain, which help to improve patient outcomes.

Cite this article: EFORT Open Rev 2020;5:534-543. DOI: 10.1302/2058-5241.5.200031

Why Reintervention After Total Knee Arthroplasty Fails? A Consecutive Cohort of 1170 Surgeries

BACKGROUND

The aim of this study was to analyze why contemporary reintervention after total knee arthroplasty (RiTKA) fails.

METHODS

Between January 2006 and December 2010, from a multicenter cohort of 1170 RiTKAs, we assessed all failures of RiTKA requiring additional surgery. All indications for the index reintervention were included. The minimum follow-up period was 3 years.

RESULTS

A total of 192 (16.4%) patients required additional surgery after RiTKA (re-reintervention). The mean follow-up period was 7.7 years. Mean age was 69.2 years. The mean time to re-reintervention was 9.6 months with 90.1% of rTKA failure occurring within the first two years. Infection was the main cause of new surgery after RiTKA (47.9%; n = 92/192). Other causes included extensor mechanism pathology (14.6%), stiffness (13.5%), pain (6.8%), aseptic loosening (5.2%), laxity (5.2%), periprosthetic fracture (3.6%), and wound pathology (3.1%). In four groups, the main indication for re-reintervention was recurrence of the pathology leading to the first reintervention: RiTKA for infection (59/355, 16.6%, P < .05), stiffness (18/174, 10.3%, P < .05), extensor mechanism failure (9/167, 5.4%, P < .05), and RiTKA for pain (4/137, 2.9%, P = .003). Global survival curve analysis found 87.9% survivorship without re-reintervention at one year and 83% at eight years.

CONCLUSION

Contemporary RiTKA failures mainly occur in the first two postoperative years. Infection is the main cause of failure in RiTKA. Recurrence of the initial pathology occurs in four groups of RiTKA and is the main indication for re-reintervention in these groups; infection (16.6%), stiffness (10.3%), extensor mechanism failure (5.4%), and pain (2.9%).

The diagnostic potential of low-field MRI in problematic total knee arthroplasties - a feasibility study

Purpose

Low-field MRI, allowing imaging in supine and weight-bearing position, may be utilized as a non-invasive and affordable tool to differentiate between causes of dissatisfaction after TKA (‘problematic TKA’). However, it remains unclear whether low-field MRI results in sufficient image quality with limited metal artefacts. Therefore, this feasibility study explored the diagnostic value of low-field MRI concerning pathologies associated with problematic TKA’s’ by comparing low-field MRI findings with CT and surgical findings. Secondly, differences in patellofemoral parameters between supine and weight-bearing low-field MRI were evaluated.

Methods

Eight patients with a problematic TKA were scanned using low-field MRI in weight-bearing and supine conditions. Six of these patients underwent revision surgery. Scans were analysed by a radiologist for pathologies associated with a problematic TKA. Additional patellofemoral and alignment parameters were measured by an imaging expert. MRI observations were compared to those obtained with CT, the diagnosis based on the clinical work-up, and findings during revision surgery.

Results

MRI observations of rotational malalignment, component loosening and patellofemoral arthrosis were comparable with the clinical diagnosis (six out of eight) and were confirmed during surgery (four out of six). All MRI observations were in line with CT findings (seven out of seven). Clinical diagnosis and surgical findings of collateral excessive laxity could not be confirmed with MRI (two out of eight).

Conclusion

Low-field MRI shows comparable diagnostic value as CT and might be a future low cost and ionizing radiation free alternative. Differences between supine and weight-bearing MRI did not yield clinically relevant information.

The study was approved by the Medical Research Ethics Committees of Twente (Netherlands Trial Register: Trial NL7009 (NTR7207). Registered 5 March 2018, https://www.trialregister.nl/trial/7009).

Comparative Study of the Function and Quality of Life of Patients Submitted to Total Knee Arthroplasty with Fixed and Mobile Tibial Platforms

Objective  To compare the function and quality of life of patients undergoing total knee arthroplasty (TKA) with fixed tibial platform and mobile tibial platform.

Methods  We evaluated 240 patients with knee osteoarthritis, randomized into two groups - Group A consisted of 120 patients who underwent TKA with fixed tibial platform, and the B group, consisting of 120 patients who underwent mobile platform arthroplasty. Patients were accessed according to the function and quality of life by the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the Short Form Health Survey (SF-36), and pain scores by visual analog scale (VAS) of pain, preoperatively and at 6 months, 1 year, 2 years, 4 years and 8 years of surgery.

Results  Regarding the various domains of the SF-36, we observed that the average behavior of functional capacity scores, physical aspects, pain and emotional aspects in the patient groups were statistically different during follow-up. The other domains of quality of life showed no mean differences. Regarding the pain assessed by VAS and WOMAC pain scores, we can see that it showed a mean change in follow-up in both patient groups. However, at 2 years of follow-up, they were statistically worse in group A, equaling group B in the other moments.

Conclusion  After 2 years of follow-up, we observed that pain scores and VAS were lower in the fixed platform group. However, these differences did not remain in the mid-term, suggesting that the mobile tibial platform arthroplasty has a short-term advantage, and may help in the rehabilitation process.

Preoperative Osteopathic Manipulative Therapy Improves Postoperative Pain and Reduces Opioid Consumption After Total Knee Arthroplasty: A Prospective Comparative Study

Context

Pain is a therapeutic challenge after total knee arthroplasty (TKA), and it could lead to the overuse of opioids. Few methodologically robust clinical studies have been performed to assess the effectiveness of osteopathic manipulative therapy (OMTh; manipulative care performed by non-US-trained osteopaths) for postsurgical pain.

Objective

To evaluate the effectiveness of standardized preoperative OMTh on early postoperative pain and opioid consumption after TKA.

Methods

This comparative, nonrandomized study took place from 2013 to 2015 and included patients who had primary unilateral TKA for osteoarthritis in a knee that had not undergone any previous surgery. Patients were divided into 2 consecutive groups: 1 group received traditional preoperative management, and the other group received associated preoperative OMTh (general OMTh [rhythmic mobilization of all the body joints, from the ankles to the skull, using long-lever manipulation] and myofascial relaxation). The primary evaluation criterion was knee pain at rest 1 month after surgery: 0 (no pain) to 100 (the worst imaginable pain). The secondary evaluation criteria were: (1) knee pain while walking 1 month after surgery, (2) average weekly knee pain during the first month after surgery, (3) the presence of night pain and the consumption of sleeping pills and opioids or morphine at least once per week, (4) the International Knee Society scores and the Western Ontario and McMaster University Osteoarthritis index at postoperative 6 months and 1 year. The number of patients needed for a superiority trial was determined.

Results

No eligible patient refused OMTh when proposed. Seventy patients were evaluated (mean [SD] age, 75 [8] years; 47 women and 23 men). The 2 treatment groups contained 35 patients each. At postoperative month 1, the OMTh group had significantly less pain at rest (mean [SD], 6.8 [6] vs 20.9 [17.3]; P=.00001) and while walking (7.9 [9.4] vs 23.5 [20.6]; P=.0001) compared with the group that received traditional preoperative management. The consumption of opioids during the first postoperative week was significantly lower in the OMTh group (P=.0001). No statistically significant difference was found in the International Knee Society or Western Ontario and McMaster University Osteoarthritis scores between the 2 groups at 6 months and 1 year of follow-up.

Conclusion

Standardized preoperative OMTh was found to be effective in reducing pain in the first month after TKA for osteoarthritis and significantly reduced opioid consumption during the first postoperative week.

Bone SPECT/CT has excellent sensitivity and specificity for diagnosis of loosening and patellofemoral problems after total knee arthroplasty

PURPOSE

The primary purpose of this retrospective study with prospectively collected data was to evaluate the clinical value of SPECT/CT, in particular its impact on clinical diagnosis and patient management, in patients with pain, stiffness, or swelling after primary total knee arthroplasty (TKA). The secondary purpose was to determine the sensitivity and the specificity of SPECT/CT for different pathologies such as loosening and patellofemoral overloading.

METHODS

A retrospective analysis was carried out on 214 knees in 202 consecutive patients (mean age 69 ± 11 years) with persistent or recurrent knee pain after TKA. All patients underwent clinical examination, standardised radiographs, and 99mTc-hydroxymethane diphosphonate (HDP) SPECT/CT as part of a routine diagnostic algorithm. The diagnoses before and after SPECT/CT and final treatment were recorded. TKA component position was routinely measured on 3D-reconstructed images. Intensity and anatomical distribution of bone tracer uptake were determined.

RESULTS

SPECT/CT changed the clinical diagnosis and final treatment in 139/214 (65%) knees. In 117 (54.7%) out of 214 patients, revision surgery was proposed following SPECT/CT. Early onset of pain was significantly (p = 0.011) correlated with tibiofemoral stress pattern in SPECT/CT. A total of 86 knees (40.2%) were surgically revised using semi-constrained or fully constrained TKA. In 35 patients, a secondary patellar resurfacing was performed. SPECT/CT showed the clinical diagnosis to be incorrect for suspicion of tibial component loosening in 56 patients (26.2%), femoral component loosening in 53 patients (24.8%), and patellofemoral overloading/progressive patellofemoral osteoarthritis in 26 patients (12.1%) and provided different underlying causes of persistent knee pain after TKA. Likewise, SPECT/CT identified tibial component loosening in 8 patients (3.7%), femoral component loosening in 4 patients (1.9%), and patellofemoral OA in 71 patients (33.2%) without prior clinical suspected diagnosis. The sensitivity and specificity of SPECT/CT for detection of patellofemoral OA was 96.5% and 96.2%, respectively. The sensitivity and specificity for detection of tibial component loosening was 96.0% and 100%, respectively. The sensitivity and specificity for detection of femoral component loosening was 95.0% and 100%, respectively.

CONCLUSION

The diagnostic benefits of SPECT/CT in the challenging and complex cohort of patients with pain after primary TKA have been proven. The excellent sensitivity and specificity for detection of tibial or femoral component loosening and diagnosis of patellofemoral OA have been surgically confirmed. Due to the benefits in establishing the correct diagnosis, SPECT/CT should be implemented as part of the routine diagnostic algorithm for patients with pain after primary TKA.

LEVEL OF EVIDENCE

II.

Are perioperative interventions effective in preventing chronic pain after primary total knee replacement? A systematic review

OBJECTIVES

For many people with advanced osteoarthritis, total knee replacement (TKR) is an effective treatment for relieving pain and improving function. Features of perioperative care may be associated with the adverse event of chronic pain 6 months or longer after surgery; effects may be direct, for example, through nerve damage or surgical complications, or indirect through adverse events. This systematic review aims to evaluate whether non-surgical perioperative interventions prevent long-term pain after TKR.

METHODS

We conducted a systematic review of perioperative interventions for adults with osteoarthritis receiving primary TKR evaluated in a randomised controlled trial (RCT). We searched The Cochrane Library, MEDLINE, Embase, PsycINFO and CINAHL until February 2018. After screening, two reviewers evaluated articles. Studies at low risk of bias according to the Cochrane tool were included.

INTERVENTIONS

Perioperative non-surgical interventions; control receiving no intervention or alternative treatment.

PRIMARY AND SECONDARY OUTCOME MEASURES

Pain or score with pain component assessed at 6 months or longer postoperative.

RESULTS

44 RCTs at low risk of bias assessed long-term pain. Intervention heterogeneity precluded meta-analysis and definitive statements on effectiveness. Good-quality research provided generally weak evidence for small reductions in long-term pain with local infiltration analgesia (three studies), ketamine infusion (one study), pregabalin (one study) and supported early discharge (one study) compared with no intervention. For electric muscle stimulation (two studies), anabolic steroids (one study) and walking training (one study) there was a suggestion of more clinically important benefit. No concerns relating to long-term adverse events were reported. For a range of treatments there was no evidence linking them with unfavourable pain outcomes.

CONCLUSIONS

To prevent chronic pain after TKR, several perioperative interventions show benefits and merit further research. Good-quality studies assessing long-term pain after perioperative interventions are feasible and necessary to ensure that patients with osteoarthritis achieve good long-term outcomes after TKR.

Enhanced preoperative education about continuous femoral nerve block with patient-controlled analgesia improves the analgesic effect for patients undergoing total knee arthroplasty and reduces the workload for ward nurses

Background

Total knee arthroplasty (TKA) is the most common treatment for end-stage knee osteoarthritis and continuous femoral nerve block (CFNB) has become the gold standard for analgesia. But the lack of knowledge about CFNB and patient-controlled analgesia (PCA) often leads to inappropriate dose of medications and increased workload for ward nurses.

Methods

After retrospectively registering to http://www.chictr.org.cn (ChiCTR1800018957), 60 patients undergoing unilateral TKA were randomly divided into groups A and B (n = 30 each). Patients in group B and their families received a nurse-led preoperative visit the day before surgery focusing on PCA educational pamphlets for postoperative pain management. Before returning to the ward, patients and their families in both groups received face-to-face PCA pump operation training. The usual postoperative follow-up was performed by nurse anesthetists for 2 consecutive days. Visual Analogue Scale (VAS) scores at rest and during movement, knowledge of the PCA evaluated by a ten-question questionnaire, knee flexion angles, and the number of PCA-related nurse calls were recorded.

Results

The VAS scores at rest and during movement of the patients in group B were both significantly lower than in group A on postoperative days 1 and 2. The questionnaire scores of the patients in group B were much higher than those in group A on postoperative day 1, but not on day 2. Patients in the 2 groups had similar knee flexion on postoperative days 1 and 2. Patients in group B asked for assistance from the ward nurses with the PCA fewer times than those in group A, and the ward nurses were more satisfied with the analgesic protocol in group B.

Conclusions

Enhanced preoperative education for CFNB with PCA can provide patients with a better grasp of postoperative pain management, improve the postoperative analgesic effect after TKA, and reduce the PCA-related workload for ward nurses.

Trial registration

This study was retrospectively registered to ChiCTR (identifier: ChiCTR1800018957) on October 18, 2018.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0826-3) contains supplementary material, which is available to authorized users.

Persistent knee pain after uncomplicated total knee arthroplasty secondary to undiagnosed spondylotic myelopathy: a case report

Introduction

Knee osteoarthritis and cervical spondylotic myelopathy are both frequent disorders in the aging patient. Total knee arthroplasty is an increasingly common surgical procedure, with approximately 20% of patients describing persistent knee pain after the procedure, for which it is often difficult to find a cause. We review known reasons for pain after total knee arthroplasty and present a new clinically challenging case of persistent knee pain due to previously undiagnosed cervical spondylotic myelopathy.

Case presentation

Our patient presented with painful knee spasms after an uncomplicated total knee arthroplasty. Her workup revealed cervical spondylotic myelopathy with isolated changes in tone in the affected extremity as well as weakness and atrophy in non-painful limbs. Her clinical status improved after cervical decompression and fusion. We perform a literature review for prior reports of isolated knee pain due to cervical spondylotic myelopathy and find no previous reported association with total knee arthroplasty.

Discussion

Cervical spondylotic myelopathy is the most common spinal cord disorder in older adults. Incidence increases with age and the clinical manifestations may present with a variety of neurological findings. Careful musculoskeletal and neurologic examination is critical to an accurate and timely diagnosis.

Prevention and Treatment of Chronic Postsurgical Pain: A Narrative Review

Chronic postsurgical pain affects between 5 and 75% of patients, often with an adverse impact on quality of life. While the transition of acute to chronic pain is a complex process-involving multiple mechanisms at different levels-the current strategies for prevention have primarily been restricted to perioperative pharmacological interventions. In the present paper, we first present an up-to-date narrative literature review of these interventions. In the second section, we develop several ways by which we could overcome the limitations of the current approaches and enhance the outcome of our surgical patients, including the better identification of individual risk factors, tailoring treatment to individual patients, and improved acute and subacute pain evaluation and management. The third and final section covers the treatment of established CPSP. Given that evidence for the current therapeutic options is limited, we need high-quality trials studying multimodal interventions matched to pain characteristics.

Knee implant kinematics are task-dependent

Although total knee arthroplasty (TKA) has become a standard surgical procedure for relieving pain, knowledge of the in vivo knee joint kinematics throughout common functional activities of daily living is still missing. The goal of this study was to analyse knee joint motion throughout complete cycles of daily activities in TKA subjects to establish whether a significant difference in joint kinematics occurs between different activities. Using dynamic videofluoroscopy, we assessed tibio-femoral kinematics in six subjects throughout complete cycles of walking, stair descent, sit-to-stand and stand-to-sit. The mean range of condylar anterior-posterior translation exhibited clear task dependency across all subjects. A significantly larger anterior-posterior translation was observed during stair descent compared to level walking and stand-to-sit. Local minima were observed at approximately 30° flexion for different tasks, which were more prominent during loaded task phases. This characteristic is likely to correspond to the specific design of the implant. From the data presented in this study, it is clear that the flexion angle alone cannot fully explain tibio-femoral implant kinematics. As a result, it seems that the assessment of complete cycles of the most frequent functional activities is imperative when evaluating the behaviour of a TKA design in vivo.

Periprosthetic infection is the major indication for TKA revision - experiences from a university referral arthroplasty center

Background

We hypothesized, that periprosthetic joint infection (PJI) accounts for the major proportion of first (primary) and repeated (secondary) Total Knee Arthroplasty revisions at our university referral arthroplasty center.

Methods

One thousand one hundred forty-three revisions, performed between 2008 and 2016 were grouped into primary (55%) and secondary (45%) revisions. The rate of revision indications was calculated and indications were categorized by time after index operation. The odds ratios of the indications for primary versus secondary revision were calculated.

Results

In the primary revision group PJI accounted for 22.3%, instability for 20.0%, aseptic loosening for 14.9% and retropatellar arthrosis for 14.2%. PJI (25.6%) was the most common indication up to 1 year after implantation, retropatellar arthrosis (26.8%) 1–3 years and aseptic loosening (25.6%) more than 3 years after implantation.

In the secondary revision group PJI accounted for 39.7%, aseptic loosening for 16.2% and instability for 13.2%. PJI was the most common indication at any time of revision with 43.8% up to one, 35.4% 1–3 years and 39.4% more the 3 years after index operation.

The odds ratios in repeated revision were 2.32 times higher (p = 0.000) for PJI. For instability and retropatellar arthrosis the odds ratios were 0.60 times (p = 0.006) and 0.22 times (p = 0.000) lower.

Conclusions

PJI is the most common indication for secondary TKA revision and within one year after primary TKA. Aseptical failures such as instability, retropatellar arthrosis and aseptical loosening are the predominant reasons for revision more than one year after primary TKA.

Chronic pain after total knee arthroplasty

Despite a good outcome for many patients, approximately 20% of patients experience chronic pain after total knee arthroplasty (TKA).

Chronic pain after TKA can affect all dimensions of health-related quality of life, and is associated with functional limitations, pain-related distress, depression, poorer general health and social isolation.

In both clinical and research settings, the approach to assessing chronic pain after TKA needs to be in-depth and multidimensional to understand the characteristics and impact of this pain. Assessment of this pain has been inadequate in the past, but there are encouraging trends for increased use of validated patient-reported outcome measures.

Risk factors for chronic pain after TKA can be considered as those present before surgery, intraoperatively or in the acute postoperative period. Knowledge of risk factors is important to guide the development of interventions and to help to target care. Evaluations of preoperative interventions which optimize pain management and general health around the time of surgery are needed.

The causes of chronic pain after TKA are not yet fully understood, although research interest is growing and it is evident that this pain has a multifactorial aetiology, with a wide range of possible biological, surgical and psychosocial factors that can influence pain outcomes.

Treatment of chronic pain after TKA is challenging, and evaluation of combined treatments and individually targeted treatments matched to patient characteristics is advocated. To ensure that optimal care is provided to patients, the clinical- and cost-effectiveness of multidisciplinary and individualized interventions should be evaluated.

Cite this article: EFORT Open Rev 2018;3:461-470. DOI: 10.1302/2058-5241.3.180004

Clinical- and cost-effectiveness of the STAR care pathway compared to usual care for patients with chronic pain after total knee replacement: study protocol for a UK randomised controlled trial

Background

Approximately 20% of patients experience chronic pain after total knee replacement. There is little evidence for effective interventions for the management of this pain, and current healthcare provision is patchy and inconsistent. Given the complexity of this condition, multimodal and individualised interventions matched to pain characteristics are needed. We have undertaken a comprehensive programme of work to develop a care pathway for patients with chronic pain after total knee replacement. This protocol describes the design of a randomised controlled trial to evaluate the clinical- and cost-effectiveness of a complex intervention care pathway compared with usual care.

Methods

This is a pragmatic two-armed, open, multi-centred randomised controlled trial conducted within secondary care in the UK. Patients will be screened at 2 months after total knee replacement and 381 patients with chronic pain at 3 months postoperatively will be recruited. Recruitment processes will be optimised through qualitative research during a 6-month internal pilot phase. Patients are randomised using a 2:1 intervention:control allocation ratio. All participants receive usual care as provided by their hospital. The intervention comprises an assessment clinic appointment at 3 months postoperatively with an Extended Scope Practitioner and up to six telephone follow-up calls over 12 months. In the assessment clinic, a standardised protocol is followed to identify potential underlying causes for the chronic pain and enable appropriate onward referrals to existing services for targeted and individualised treatment. Outcomes are assessed by questionnaires at 6 and 12 months after randomisation. The co-primary outcomes are pain severity and pain interference assessed using the Brief Pain Inventory at 12 months after randomisation. Secondary outcomes relate to resource use, function, neuropathic pain, mental well-being, use of pain medications, satisfaction with pain relief, pain frequency, capability, health-related quality of life and bodily pain. After trial completion, up to 30 patients in the intervention group will be interviewed about their experiences of the care pathway.

Discussion

If shown to be clinically and cost-effective, this care pathway intervention could improve the management of chronic pain after total knee replacement.

Trial registration

ISRCTN registry (ISRCTN92545361), prospectively registered on 30 August 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2516-8) contains supplementary material, which is available to authorized users.

Internal femoral component rotation adversely influences load transfer in total knee arthroplasty: a cadaveric navigated study using the Verasense device

PURPOSE AND HYPOTHESIS

Correct femoral component rotation at knee arthroplasty influences patellar tracking and may determine function at extremes of movement. Additionally, such malrotation may deleteriously influence flexion/extension gap geometry and soft tissue balancing kinematics. Little is known about the effect of subtle rotational change upon load transfer across the tibiofemoral articulation. Our null hypothesis was that femoral component rotation would not influence load across this joint in predictable manner.

METHODS

A cadaveric study was performed to examine load transfer using the orthosensor device, respecting laxity patterns in 6° of motion, to examine load across the medial and lateral compartments across a full arc of motion. Mixed-effect modelling allowed for quantification of the effect upon load with internal and external femoral component rotation in relation to a datum in a modern single-radius cruciate-retaining primary knee design.

RESULTS

No significant change in maximal laxity was found between different femoral rotational states. Internal rotation of the femoral component resulted in significant increase in medial compartment load transfer for knee flexion including and beyond 60°. External rotation of the femoral component within the limits studied did not influence tibiofemoral load transfer.

CONCLUSIONS

Internal rotation of the femoral component will adversely influence medial compartment load transfer and could lead to premature polyethylene wear on the medial side.

Fibroblasts Promote Inflammation and Pain via IL-1α Induction of the Monocyte Chemoattractant Chemokine (C-C Motif) Ligand 2

Fibroblasts persist within fibrotic scar tissue and exhibit considerable phenotypic and functional plasticity. Herein, we hypothesized that scar-associated fibroblasts may be a source of stress-induced inflammatory exacerbations and pain. To test this idea, we used a human model of surgery-induced fibrosis, total knee arthroplasty (TKA). Using a combination of tissue protein expression profiling and bioinformatics, we discovered that many months after TKA, the fibrotic joint exists in a state of unresolved chronic inflammation. Moreover, the infrapatellar fat pad, a soft tissue that becomes highly fibrotic in the post-TKA joint, expresses multiple inflammatory mediators, including the monocyte chemoattractant, chemokine (C-C motif) ligand (CCL) 2, and the innate immune trigger, IL-1α. Fibroblasts isolated from the post-TKA fibrotic infrapatellar fat pad express the IL-1 receptor and on exposure to IL-1α polarize to a highly inflammatory state that enables them to stimulate the recruitment of monocytes. Blockade of fibroblast CCL2 or its transcriptional regulator NF-κB prevented IL-1α-induced monocyte recruitment. Clinical investigations discovered that levels of patient-reported pain in the post-TKA joint correlated with concentrations of CCL2 in the joint tissue, such that the chemokine is effectively a pain biomarker in the TKA patient. We propose that an IL-1α-NF-κB-CCL2 signaling pathway, operating within scar-associated fibroblasts, may be therapeutically manipulated for alleviating inflammation and pain in fibrotic joints and other tissues.