German Congress of Orthopaedics and Traumatology (DKOU 2025)
Preoperative MRI assessment of intra-articular scar tissue and its impact on clinical outcomes in knee arthrofibrosis patients undergoing arthroscopic arthrolysis
2BG Clinic Hamburg, Hamburg, Deutschland
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Objectives and questions: Knee stiffness up to its maximum form of arthrofibrosis is a risk after knee surgery that is related to intra-articular fibrotic tissue. This study investigated the ability of MRI to detect and quantify fibrotic tissue and explored its association with clinical outcomes after arthroscopic arthrolysis.
Material and methods: A retrospective analysis of 31 patients was conducted, categorizing cases as non-arthrofibrosis (nAFoK) or arthrofibrosis of the knee (AFoK) based on established criteria: (1) significant ROM loss, (2) stiffness persisting beyond three months post-procedure, (3) absence of mechanical blockade or infection, and (4) insufficient ROM improvement despite intensive physiotherapy. Patients meeting all criteria were classified as AFoK; those with knee fibrosis who did not were classified as nAFoK. Preoperative MRIs were used to measure fibrotic tissue thickness (TT) in six knee compartments. Functional outcomes were evaluated using the International Knee Documentation Committee (IKDC) score, and the impact of preoperative measured TT on postoperative outcomes was analyzed.
Results: A total of 31 patients were included in the study, with 10 meeting the criteria for AFoK and 21 classified as nAFoK. Fibrous TT was significantly greater in AFoK patients compared to nAFoK, particularly in the suprapatellar recess and anterior knee compartments (p < 0.001). Patients with preoperative flexion deficits (<100°) demonstrated significantly increased TT in multiple knee compartments (p < 0.001), which correlated with reduced postoperative International Knee Documentation Committee (IKDC) scores. Similarly, patients with both flexion and extension deficits exhibited higher TT across all knee compartments and significantly worse functional outcomes (p < 0.0001). A threshold TT of 4.4–6.1 mm was identified as predictive of postoperative functional limitations, with thicker tissue associated with lower IKDC scores in most knee compartments.
Discussion and conclusions: MRI effectively detects and quantifies fibrotic tissue, predicts functional outcomes, and supports surgical planning for arthrolysis. Threshold TT values (4.4–6.1 mm) could guide treatment. Further research is needed to confirm these findings.
