Table 4.

Incidence of patella baja and pseudo-patella baja

	Hemophilia	Rheumatoid arthritis	p-Value
Preoperative
Normal/patella bajaa/PPBb	34/14/0	88/4/0	< 0.001‡
Postoperative
Normal/patella bajaa/PPBb	28/15/5	80/4/8	< 0.001‡

^‡Statistical significance was analyzed in comparison of postoperative incidence of patella baja or pseudo-patella baja in patients with normal preoperative patellar height

^aPatella baja: both Insall–Salvati ratio (< 0.8) and Blackburne–Peel ratio (< 0.54) are abnormally low

^bPPB (pseudo-patella baja): normal Insall–Salvati ratio (0.8–1.2) but low Blackburne–Peel ratio (< 0.54)