6-year follow-up of 84 patients with cartilage defects in the knee: Knee scores improved but recovery was incomplete

BACKGROUND AND PURPOSE: The natural history of focal cartilage injury is largely unknown. In this study we investigated 6-year outcomes in patients with arthroscopically verified, focal, full-thickness cartilage injuries of the knee. METHODS: In a previous report (baseline study) of 993 knee arthroscopies, 98 patients were less than 50 years old at baseline and showed grade 3–4 focal cartilage injury, as assessed with the International Cartilage Repair Society (ICRS) scale. In the present study, 84 of the 98 patients completed follow-ups at median 6.1 (5.3–7.8) years after baseline assessments. At baseline, the patients had undergone different types of cartilage repair (n = 34) or had no treatment or only debridement (n = 64) for their cartilage injury. The follow-up included evaluations with the ICRS knee evaluation form, the Lysholm score, and other knee evaluation tests. 68 patients underwent radiographic assessments with weight bearing. RESULTS: Improvements compared to baseline were noted in the average ICRS functional score, visual analog scale (VAS) pain score, and the patients' rating of the function in the affected knee compared to the contra-lateral knee. However, the average ICRS activity level had decreased from baseline. The average Lysholm score was 76 (SD 21). 19 patients had Kellgren-Lawrence grades 2–3 in the affected knee and 6 patients had grades 2–3 in the contralateral knee. There was a statistically significant difference between affected and contralateral knees. INTERPRETATION: Patients with arthroscopically diagnosed ICRS grade 3–4 cartilage injuries in the knee may show improvement in knee function over the following 5–8 years, with or without cartilage repair. However, knee function remains substantially affected. Further studies are needed to determine whether cartilage surgery can yield better functional outcomes than non-surgical or less invasive surgical treatments.