Relationship between the deep flexion of the knee joint and the dynamics of the infrapatellar fat pad after anterior cruciate ligament reconstruction via ultrasonography.

The study included only 28 patients, with 12 in the possible group and 16 in the impossible group. Only the superficial part of the infrapatellar fat pad was measured, so the deep part was not assessed. The researchers could not evaluate how much of the fat pad was resected during surgery or where, which may have affected thickness. Tissue fibrosis was only suspected from ultrasound echo intensity; the fat pad tissue was not examined under a microscope. All participants had full knee range of motion at entry, so the findings may not apply to patients with restricted motion. The study looked at seiza, a Japanese kneeling posture, so it may not translate to patients whose sitting goals are different. The design was cross-sectional at 3 months, so it shows association rather than cause.

The research received no specific grant from public, commercial, or not-for-profit funding agencies, and the authors declared no conflict of interest.

Do not read these ultrasound differences as proof that the fat pad causes inability to sit in seiza. The study was small, measured only the superficial fat pad at 3 months, and did not examine tissue fibrosis or surgical resection, so it cannot show cause.