Summary

We investigated the mid- to long-term outcomes of 22 patients (23 knees) who underwent OWHTO, finding that while regenerated cartilage quality did not significantly affect X-ray measurements, VAS, or JKOM scores, better tissue regeneration was associated with improved JKOOS "symptoms" scores.

Abstract

【Introduction】
We previously reported that the histological assessment of regenerated cartilage tissue at the time of screw removal after OWHTO did not affect clinical outcomes two years postoperatively. However, its impact on mid- to long-term outcomes remains unclear. Therefore, we aimed to clarify the relationship between regenerated cartilage tissue and mid- to long-term outcomes.

【Methods】
The study included patients who consented to biopsy of regenerated tissue during screw removal after OWHTO and were followed up for more than five years postoperatively. The regenerated tissue was classified into two groups: "good" with an ICRS II scoring system total score of 50 or more, and "poor" with a score below 50. At the final follow-up, we assessed plain X-rays (KL classification, %MA, FTA, PS), VAS, and patient-reported outcomes (JKOM, JKOOS), and compared the two groups (t-test, χ² test, p<0.05).

【Results】
Of the 28 knees, 23 knees were followed up for more than five years. There were 11 knees in the good group and 12 knees in the poor group, with an average follow-up period of 75.1 months. No significant differences were observed between the two groups in the various X-ray measurements at the final follow-up. Additionally, there were no significant differences between the groups in VAS and JKOM. However, in JKOOS, the good group had significantly higher scores in the "symptoms" category.

【Conclusion】
We examined the mid- to long-term outcomes of 22 cases (23 knees) that underwent biopsy during screw removal after OWHTO. Good tissue regeneration was found to affect some aspects of JKOOS in the mid- to long-term.