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

CompartmentM/LM/LM/LM/LM/LM/LM/LM/LM/LM/LM/L
JSN, joint space narrowing; L, lateral; M, medial.
Expected and observed number of knees in each subgroups.
JSN score0/01/02/03/04/00/10/20/30/41/1>1/>1
Expected (n)>20>20>20>20>20>20>20>20>20>20>20
Observed (n)11403342171416100811