Metal Artifact Reduction Sequence MRI Abnormalities in Asymptomatic Patients with a Ceramicon-Polyethylene Total Hip Replacement
- J.M. Jennings, J.R. Martin, R.H. Kim, C.C. Yang, T.M. Miner, D.A. Dennis, Colorado Joint Replacement, Denver, Colorado, USA
- J Bone Joint Surg Am. 2017;99:593-8 d . http://dx.doi.org/10.2106/JBJS.16.00910
- Level of Evidence
- Level 4
Jennings et al. investigated the frequency and the type of fluid collections in 44 asymptomatic total hip arthroplasty (THA) patients with ceramic-on-highly crosslinked Polyethylene (CoXP; BIOLOX®delta, XP without antioxidant) bearings with a total of 50 hips. Only pain-free patients with at least 2-year follow up with appropriate positioned implant components (stem non-modular, no sleeves) and serial radiographs available within 2 years prior to study enrollment were included. MRI images were interpreted by one musculoskeletal radiologist and one arthroplasty surgeon.
Mean follow up was 3.4 years. The mean Harris Hip Score of the patients was 98.5. Of the 50 hips, 9 showed fluid collections visible on the MRI scan and 5 hips intracapsular synovitis with a mean synovial thickness of 5.1 mm. Two of those hips were considered to have a thickened synovium ( > 6 mm). Further 4 hips showed extra-articular fluid collection with intracapsular communication with a mean synovial thickness of 6 mm. Two of those were considered to have a thickened synovium. In the whole cohort of patients with fluid filled collections no tissue destructions or solid lesions were found. Radiographic findings did not indicate implant loosening or other signs of adverse local tissue reactions (ALTR) in any of the patients. In 3 hips there were signs for potential early osteolysis. However, subtle osteolysis may be difficult to interpret on MRI. The identified osteolytic lesions may also have been subclinical preoperative lesions, which could not be identified with preoperative radiographs.
The authors conclude that fluid collections are not uncommon in asymptomatic patients with well-functioning CoXP bearings and are likely benign without clinical consequence at least at short-term follow-up. Nevertheless, the patients should be monitored closely in case these fluid collections progress from benign to symptomatic or destructive lesions.