Table 9 The Extrusion width (EW), Inner width (IW), and Total width (EW + IW) of the medial and lateral menisci were compared between the PAONK group and the matched control group at the 2 periods, before meniscectomy and at the time of diagnosis of PAONK, respectively. The comparisons were made using Mann-Whitney U test. Concerning the time of the MRI examination, “After meniscectomy^a” means “At the time of diagnosis of PAONK” in the PAONK group and “At the time of the second-look MRI taken 6 – 12 months after the meniscectomy” in the Control group

Medial

Extrusion width (EW)

Before meniscectomy

4.7 (1.4)

3.0 (1.3)

P = 0.0195

After meniscectomy^a

5.9 (1.1)

3.4 (1.4)

P = 0.0009

Inner width (IW)

Before meniscectomy

4.4 (2.4)

6.3 (1.7)

N.S.

After meniscectomy^a

0.6 (1.7)

3.9 (1.0)

P = 0.0001

Total width (EW + IW)

Before meniscectomy

9.1 (1.5)

9.3 (1.5)

N.S.

After meniscectomy^a

6.4 (1.2)

7.2 (1.3)

N.S.

Lateral

Extrusion width (EW)

Before meniscectomy

−0.2 (0.8)

0.1 (1.2)

N.S.

After meniscectomy^a

−0.2 (0.9)

0.2 (1.3)

N.S.

Inner width (IW)

Before meniscectomy

9.1 (1.7)

10.8 (3.0)

N.S.

After meniscectomy^a

8.9 (1.8)

10.4 (3.3)

N.S.

Total width (EW + IW)

Before meniscectomy

8.9 (1.3)

10.9 (2.6)

N.S.

After meniscectomy^a

8.7 (1.6)

10.6 (2.9)

N.S.