Background: The goal of this longitudinal study was to investigate the fate of the lateral femoral notch (LFN), which is frequently seen as an impaction fracture of the lateral femoral condyle in patients with anterior cruciate ligament (ACL) tears.
Methods: Patients who underwent early ACL reconstruction between 2006 and 2010 were reviewed. If post-injury magnetic resonance images showed an LFN greater than 1.5 mm in depth, patients with untreated LFN were followed. Two blinded observers performed quantitative and qualitative imaging analysis.
Results: Sixteen patients (five women, 11 men) were available for follow-up nine years (six to 10 years) post-injury. The median defect area of the LFN significantly decreased from 2.3 cm2 (range: 0.9-3.8 cm2) to 1.6 cm2 (range: 0.4-3.2 cm2) (P < .001). The defect depth did not significantly change from 2.3 mm (range: 2.0-3.6 mm) to 2.5 mm (range: 1.3-3.6 mm) (P > .05). The International Cartilage Repair Society (ICRS) score increased from 1.5 (range: 0-3) post-injury to 2.0 (range: 0-4) at follow-up (P < .01). The Lysholm score was 93 (72-100), the Tegner activity level was 6 (3-9) and the knee injury and osteoarthritis outcome score (KOOS) score was 97 (91-100).
Conclusions: The defect area of the LFN decreased overtime, whereas the depth of the impression remained. Focal cartilage lesions were found in all except two patients post-injury and progressed during follow-up. However, patient-reported outcome scores were satisfying.
Keywords: ACL; Anterior cruciate ligament; Impaction fracture; Lateral femoral notch; MRI.
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