Christiaan H. W. Heusdens

Background: Osteoarthritis is a highly prevalent and debilitating joint disease. Some patients continue to experience substantial symptoms despite recommended, well-conducted treatment, but the absence of a widely accepted definition of “refractory OA” complicates their identification and management. Objective: To establish an international, multidisciplinary consensus-based clinical definition of refractory knee osteoarthritis (OA). Design: Systematic literature review followed by a two-round Delphi consensus study. Data Sources and Methods: PubMed, MEDLINE, PreMEDLINE, and Embase were searched without language or publication date restrictions to identify definitions and operational criteria for refractory, difficult-to-treat, or treatment-failure OA. The findings informed 15 statements developed by a 13-member international, multidisciplinary Technical Expert Panel, supported by a methodologist and a scientific librarian. Two anonymous voting rounds were conducted between June and August 2025, with consensus predefined as at least 85% of ratings within the same three-point region of a nine-point Likert scale. In round 1 participants could propose additional statements for voting. Final statements were discussed at the 8th International Symposium on Intra-Articular Treatment Congress in October 2025. Results: Of 3047 records identified, 98 were screened and 43 publications (27 original articles and 16 reviews) were included. Consensus was achieved for 13 of 15 statements: nine in round 1 with unanimous agreement and four after revision in round 2. Osteoarthritis (OA) was assessed considering its causes, features, and impact on daily life. Experts took into account symptoms, progression, and treatment response, highlighting the need for optimal management. Refractory OA was defined as: persistent symptoms (at least 3-6 months) and altered quality of life despite optimized, guideline-based multimodal conservative OA therapy. Conclusions: A consistent definition of refractory knee OA (ROA) can identify patients with high unmet needs, support medical and surgical decision-making, and standardize eligibility for future research.

Purpose: Knee joint distraction (KJD) offers a joint preserving alternative for relatively young patients with severe knee osteoarthritis (OA). The aim of this study was to assess the clinical and radiographic success of KJD in patients with severe OA. Methods: This prospective case series comprised 26 consecutive patients undergoing KJD due to severe knee OA. Clinical and radiographic outcomes were collected at baseline and at 1‐ and 2‐year follow‐up. Complication, reoperation and conversion rates to a primary knee arthroplasty were collected. The patient‐reported outcome measures (PROMs) were the Knee Injury and Osteoarthritis Outcome Score (KOOS), the 36‐item Short Form Health Survey (SF‐36) and the Visual Analogue Scale (VAS) for pain. The radiographs were analysed using an artificial intelligence (AI) based software package to extract compartmental joint space width (JSW), joint space area (JSA) and compartmental imbalance. Results: Pin tract infections were common, affecting 13 (50%) patients. Five patients (19.2%) received primary knee arthroplasty within the 2‐year follow‐up period. Significant increases ( p < 0.05) were observed in the JSW and JSA of the most affected compartment, leading to significant improvements in compartmental imbalance. Significant improvements were also observed in all KOOS subscales ( p < 0.001) which sustained for 2 years. The VAS for pain scores were also significantly improved ( p < 0.001), as were the SF‐36 subscales ( p < 0.05) with the exception of the general health subscale. Conclusion: This case series demonstrates that KJD provides symptomatic relief amongst young patients with knee OA after failed conservative treatment. A significant increase in the JSW and JSA was observed, which may indicate cartilage regeneration. KJD could be an alternative joint‐preserving intervention with potential to delay the need for primary arthroplasty. Level of Evidence: Level IV, prospective case series.

Objectives: This study aimed to apply the International Association for the Study of Pain (IASP) grading system for identifying nociplastic pain in knee osteoarthritis (KOA) awaiting total knee arthroplasty (TKA) and propose criteria to fine-tune decision-making. In addition, the study aimed to characterize a “probable” versus “no or possible” nociplastic pain mechanism using biopsychosocial variables and compare both groups in their 1-year post-TKA response. Methods: A secondary analysis of baseline data of a longitudinal prospective study involving 197 patients with KOA awaiting total TKA in Belgium and the Netherlands was performed. Two approaches, one considering 4 and the other 3 pain locations (step 2 of the grading system), were presented. Linear mixed model analyses were performed to compare the probable and no or possible nociplastic pain mechanism groups for several preoperative biopsychosocial-related variables and 1-year postoperative pain. Also, a sensitivity analysis, comparing 3 pain mechanism groups, was performed. Results: Thirty (15.22%—approach 4 pain locations) and 46 (23.35%–approach 3 pain locations) participants were categorized under probable nociplastic pain. Irrespective of the pain location approach or sensitivity analysis, the probable nociplastic pain group included more woman, was younger, exhibited worse results on various preoperative pain-related and psychological variables, and had more pain 1-year post-TKA compared with the other group. Discussion: This study proposed additional criteria to fine-tune the grading system for nociplastic pain (except for discrete/regional/multifocal/widespread pain) and characterized a subgroup of patients with KOA with probable nociplastic pain. Future research is warranted for further validation.

Objective: This study explores the association between obesity, diabetes, and somatosensory functioning in patients with knee osteoarthritis (OA), aiming to understand how metabolic conditions are related to pain mechanisms in this patient population. We hypothesized that higher body mass index (BMI), fat mass, and glycated hemoglobin levels (HbA1c) are associated with signs of altered somatosensory functioning. Methods: A cross-sectional analysis was conducted as part of a larger multicentre prospective cohort study. Data were collected from patients awaiting total knee arthroplasty in Belgium and the Netherlands. Associations between BMI, fat mass, HbA1c, and various pain-related variables were examined employing Pearson and Spearman correlation analyses which were further analyzed with linear regression techniques. Results: The study included 223 participants. Analysis revealed a significant although weak negative correlation between fat mass and pressure pain thresholds (PPT) at multiple locations, suggesting a link between higher fat mass and increased mechanical hyperalgesia. There were no significant correlations between BMI and pain-related outcomes. HbA1c levels showed very weak positive correlations with pain measures but did not withstand correction for multiple testing. Conclusion: The findings indicate that fat mass may be closely associated with altered somatosensory functioning in patients with knee OA. However, no significant correlations were found between BMI or HbA1c levels and pain-related outcomes. Future research should focus on longitudinal studies to elucidate the causal relationships and further explore the impact of metabolic factors on pain mechanisms in this patient population. Key Points• The findings indicate that fat mass may be closely associated with altered somatosensory functioning in patients with knee OA.

Purpose: The aim of this study was to identify preoperative predictors for 1‐year posttotal knee arthroplasty (TKA) pain and pre‐ to post‐TKA pain difference in knee osteoarthritis (KOA) patients.Methods: From March 2018 to July 2023, this prospective longitudinal cohort study enrolled KOA patients awaiting TKA from four hospitals in Belgium and the Netherlands. Different biopsychosocial predictors were assessed preoperatively by questionnaires and physical examinations (input variables). The Knee injury and Osteoarthritis Outcome Score (KOOS) subscale pain was used to measure pain intensity. The absolute KOOS subscale pain score 1‐year post‐TKA and the difference score (ΔKOOS = 1‐year postoperative − preoperative) were used as primary outcome measures (output variables). Two multivariable linear regression analyses were performed.Results: Two hundred and twenty‐three participants were included after multiple imputation. Worse absolute KOOS subscale pain scores 1‐year post‐TKA and negative or closer to zero ΔKOOS subscale pain scores were predicted by self‐reported central sensitisation, lower KOA grade and preoperative satisfaction, and higher glycated haemoglobin, number of pain locations and personal control (adjusted R² = 0.25). Additional predictors of negative or closer to zero ΔKOOS subscale pain scores were being self‐employed, higher preoperative pain and function (adjusted R² = 0.37).Conclusion: This study reports different biopsychosocial predictors for both outcomes that have filtered out other potential predictors and provide value for future studies on developing risk assessment tools for the prediction of chronic TKA pain.Protocol Registration: The protocol is registered at clinicaltrials.gov (NCT05380648) on 13 May 2022.Level of Evidence: Level II.

Numerous studies have assessed the performance of magnetic resonance imaging (MRI) in detecting tears of the knee menisci using arthroscopy results as the gold standard, but few have concentrated on the nature of discordant findings. The purpose of this study was to analyze the discordances between 3T MRI and arthroscopic evaluation of the knee meniscus. Medical records of 112 patients who underwent 3T MRI and subsequent arthroscopy of the knee were retrospectively analyzed to determine the accuracy of diagnoses of meniscal tear. Compared with arthroscopy, there were 22 false-negative and 14 false-positive MR interpretations of meniscal tear occurring in 32 patients. Images with errors in diagnosis were retrospectively reviewed by two musculoskeletal radiologists in consensus and all errors were categorized as either unavoidable, equivocal or as interpretation error. Of 36 MR diagnostic errors, there were 16 (44%) unavoidable, 5 (14%) interpretation errors and 15 (42%) equivocal for meniscal tear. The largest categories of errors were unavoidable false-positive MRI diagnoses (71%) and equivocal false-negative MRI diagnoses (50%). All meniscal tears missed by MRI were treated with partial meniscectomy (n = 14) or meniscal repair (n = 8). Discordant findings between 3T MRI and arthroscopic evaluation of the knee meniscus remain a concern and primarily occur due to unavoidable and equivocal errors. Clinicians involved in the diagnosis and treatment of patients with meniscal tears should understand why and how the findings seen on knee MRI and arthroscopy may sometimes differ.

Purpose: To discuss recent literature on posterior cruciate ligament (PCL) repair and report on the clinical and radiological outcomes.Methods: A systematic review was conducted according to the PRISMA guidelines. In August 2022, three databases (PubMed, Scopus, and Cochrane Library) were searched for studies on PCL repair by two independent reviewers. Articles published between January 2000 and August 2022 focussing on the clinical and/or radiological outcomes, following PCL repair, were included. Patient demographic data, clinical evaluations, patient‑reported outcome measures, post‐operative complications and radiological outcomes were extracted.Results: Nine studies met the inclusion criteria, covering 226 patients with a mean age ranging from 22.4 to 38.8 years and mean follow‐up periods ranging from 14 to 78.6 months. Seven studies (77.8%) were level IV and two studies (22.2%) were level III. Arthroscopic PCL repair was performed in four studies (44.4%) while the remaining five studies (55.6%) described open PCL repair. In four studies (44.4%) additional suture augmentation was applied. Arthrofibrosis affected a combined total of 24 patients (11.7%; range 0–21.0%) making it the most common complication and the overall failure rate was 5.6%, ranging from 0 to 15.8%. Two studies (22.2%) performed post‐operative MRI and confirmed PCL healing.Conclusion: This systematic review indicates that PCL repair can be a safe procedure with an overall failure rate of 5.6%, ranging from 0% to 15.8%. However, more high quality research is necessary before widespread clinical implementation is warranted.Level of Evidence: IV.

Until the past decade the common thought was that the anterior cruciate ligament (ACL) was not able to heal and restore knee stability. In this manuscript a brief review of studies of the developers and the early adaptors of four different modern ACL repair techniques are presented. The present status and considerations for the future of ACL repair and its research are shared. After promising short- to midterm ACL healing results by the developers, the results of the early adaptors show more variety in terms of rerupture and reintervention for other reasons. Risk factors for failure are a young age, high preinjury sports activity level, midsubstance ruptures and impaired integrity of the ACL bundles and the synovial sheath. There is a call for more clinical data and randomized clinical trials. Conclusion: an important finding of the past decade is that the ACL is able to heal and subsequently restabilize the knee. Patient selection is emphasized: the ideal patient is a non-high athlete older than 25 and has an acute proximal one bundle ACL rupture. Further research will have to show if ACL repair could be a game changer or if history will repeat itself.

Purpose: The aim of this study is to investigate clinical and magnetic resonance imaging (MRI) outcomes after anterior cruciate ligament (ACL) repair using the suture tape augmentation (STA) technique.Methods: This prospective interventional case series included 35 patients who underwent STA ACL repair and were all followed up for 2 years. The ACL rupture was between 4 and 12 weeks old and per‐operatively confirmed repairable. The International Knee Documentation Committee (IKDC), and Lysholm and Tegner scores were collected together with return to work (RTW), return to sport (RTS), re‐rupture, and re‐intervention rate. Lachman testing was performed and ACL healing was evaluated on MRI using a grading scale based on the ACL’s morphology and signal intensity with grade 1 representing good ACL healing and grade 3 representing poor ACL healing.Results: The number of patients who returned to their pre‐rupture level for IKDC, Lysholm, and Tegner scores at 2 years of follow‐up are 17/26 (65.4%), 13/25 (52.0%), and 18/27 (66.7%) patients, respectively. Median RTW and RTS periods were 5.5 weeks (range 0–32 weeks) and 6 months (range 2–22 months), respectively. The Lachman side‐to‐side difference decreased significantly (P < 0.001) to less than 3 mm after surgery and remained stable. Four patients [11.4%, 95% CI (3.2, 26.7)] suffered from a re‐rupture and three other patients [8.6%, 95% CI (1.8, 23.1)] needed a re‐intervention for another reason than re‐rupture. MRI follow‐up of 31 patients showed overall grade 1 ACL healing in 14 (45.2%) patients, grade 2 ACL healing in 11 (35.5%) patients, and grade 3 ACL healing in 6 (19.4%) patients. A higher risk of re‐rupture was associated with grade 3 ACL healing at 6 months post‐operatively and a pre‐operative Tegner score of ≥ 7.Conclusion: This study shows that treatment of the acute, repairable ACL with the STA technique leads to a stable knee and favorable patient‐reported outcome measures (PROMs). However, the re‐rupture rate of 11.4% within the 2‐year follow‐up is a concern.Level of evidence: IV.