Catherine L. Hayter1, Matthew F. Koff1, Edwin P. Su2, Kevin M. Koch3, Parina Shah1, Stephanie L. Gold1, Hollis G. Potter1
1Department of Radiology and Imaging - MRI, Hospital for Special Surgery, New York, United States; 2Center for Hip Pain and Preservation, Hospital for Special Surgery, New York, United States; 3Applied Science Laboratory, General Electric Healthcare, Waukesha, WI, United States
Metal-on-metal (MOM) hip resurfacing can be associated an adverse local tissue response (ALTR) which may manifest as synovitis or osteolysis. The purpose of this prospective, observational study was to review patterns of osteolysis and synovitis in symptomatic and asymptomatic individuals following MOM hip resurfacing. Synovitis was detected in a similar proportion of symptomatic and asymptomatic patients. Osteolysis was only detected in symptomatic individuals. The volume of synovitis was significantly higher in subjects with ALTR (p=0.01), as were levels of serum Cr (p=0.045) and Co (p=0.01). In the ALTR group there was a significantly higher proportion of females (p=0.048) and subjects with implants with abnormal acetabular component alignment (p=0.03). MRI is the most suitable non-invasive means by which to screen symptomatic and asymptomatic patients for the presence of synovitis. MRI can differentiate individuals with a normal pseudocapsule from those patients with synovitis, which, in combination with clinical findings and serum ion levels, will help to guide patient management. The finding of a high volume of synovitis on MRI should alert the clinician towards the need for close patient monitoring and possible revision surgery, particularly in the setting of elevated serum ion levels, female sex and abnormal component alignment.