Table 1 Subgroups of tibiofemoral osteoarthritis formed by the medial and/or lateral location of joint space narrowing (JSN) and the various possible JSN scores in medial and lateral compartments.
| Compartment | M/L | M/L | M/L | M/L | M/L | M/L | M/L | M/L | M/L | M/L | M/L |
|---|---|---|---|---|---|---|---|---|---|---|---|
| JSN score | 0/0 | 1/0 | 2/0 | 3/0 | 4/0 | 0/1 | 0/2 | 0/3 | 0/4 | 1/1 | >1/>1 |
| Expected (n) | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |
| Observed (n) | 11 | 40 | 33 | 42 | 17 | 14 | 16 | 10 | 0 | 8 | 11 |
JSN, joint space narrowing; L, lateral; M, medial.
Expected and observed number of knees in each subgroups.