Table 3.

Indications for the repeated MR imaging and results of the primary and repeated MRIs. Other reasons included control imaging due to scheduled revision (8 hips), enchondroma (2 hips), squeaking hip (2 hips), suspicion of latent infection (2 hips), joint effusion in primary MRI (1 hip), and occurrence of palpable lump in lateral thigh (1 hip). 1 patient who had both HR and THR is not shown in the table

					Progressive change in classification
	HR patients		THR patients		HR patients		THR patients
Indication for repeated imaging	Unilateral	Bilateral	Unilateral	Bilateral	Unilateral	Bilateral	Unilateral	Bilateral
Control imaging due to elevated
Co and/or Cr	5	2	15	6	0	0	1	1
Occurrence of pain during follow-up	13	2	12	2	0	0	0	1
Control imaging to due increase
(> 5 ppb) in Co and/or Cr	2	1	22	6	1	0	4	2
Control imaging due to pseudotumor	2	1	5	1	0	0	0	1
Occurrence of pain and elevated
metal ions during follow-up	3	0	2	1	0	0	0	0
Control imaging due to presence of pain	2	3	1	1	0	0	0	0
Other	3	2	7	1	1	0	1	0
Total	30	11	64	18	2	0	6	5