Longitudinal assessment of cyst-like lesions of the knee and their relation to radiographic osteoarthritis and MRI-detected effusion and synovitis in patients with knee pain

Table 3 Comparison of the prevalence of cysts and bursitides at baseline and at 6-month follow-up

Type of lesion^a	Prevalence (N= 319) (V1)	Incident lesion (V2)	Increase in size (V2)^b	Decrease in size (V2)^c
Popliteal cyst^d*	128 (40)	6	23	39
Subgastrocnemius bursitis^d*	49 (15)	0	7	6
PTFJ cyst	26 (8)	0	0	0
HFP ganglion cyst	25 (8)	0	0	1
SM-MCL bursitis	13 (4)	0	0	1
PCL ganglion cyst^d	11 (4)	0	0	1
ACL ganglion cyst^d	9 (3)	0	1	1
Medial meniscal cyst^d	8 (3)	0	1	1
MCL bursitis	8 (3)	0	0	0
Prepatellar bursitis	6 (2)	0	2	0
Anserine bursitis	4 (1)	0	0	0
Iliotibial bursitis	3 (1)	1	1	1
Superficial infrapatellar bursitis^d	3 (1)	0	0	0
Deep infrapatellar bursitis	2 (<1)	0	0	0
Lateral meniscal cyst^d	0 (0)	1	1	0

Data presented as number of lesions, either grand total or subtotal for each type of cystic lesion (percentage of knees that had a cystic lesion out of total 319 knees surveyed). V1, visit at baseline; V2, visit at 6-month follow-up; N = total number of knees; PTFJ, proximal tibiofibular joint; HFP, Hoffa's fat pad; SM-MCL, semi-membranosus medial collateral ligament; PCL, posterior cruciate ligament; ACL, anterior cruciate ligament; MCL, medial collateral ligament. ^aIn order of descending frequency at baseline. ^bThe count for increase in size includes incident lesions seen at V2. ^cThe count for decrease in size includes lesions present at V1 but absent at V2. ^dMeaningful size measurements were performed in these lesions only. A significant size change was defined to be ≥5 mm change for popliteal cysts and ≥2 mm for other lesions. For lesions without size measurements, increase in size means appearance of a new lesion at V2 and decrease in size means complete resolution of a pre-existing lesion at V2. *Significant rate of change in size between baseline and follow-up (P < 0.001, by Wilcoxon signed-rank test).