Clinical: 65 y/o female with painful arthroplasty. No history of trauma.
1. Acute or subacute appearing fracture involving the medial patella. The fracture fragment measures 24 x 11 x 9 mm. The fracture extends in the AP dimension from the anterior patellar cortex and along the superficial margins of the medial patellar hardware. The fracture fragment is separated by 3 mm.
2. Small to moderate knee joint effusion which is upper limits of normal to what would be expected for arthroplasty. Given the other findings this is not favored to represent soft tissue complication of arthroplasty such as metal-on-metal disease or aseptic lymphocytic vasculitis associated lesion (ALVAL). There is also no perihardware or periarticular osteolysis.
Discussion: MRI has rapidly become the modality of choice after XRAY for the evaluation of “the painful arthroplasty” in all joints. Keep in mind these are specially designed sequences based on Hollis Potter’s and others work over the past several years and are not your routine MRI protocol. They are available at all hospitals and imaging centers we supervise. We are currently reading many hip MRI’s for a Stryker Hip recall. The attached articles are some of the better ones out there detailing the utility of MARS (metal artifact reduction sequences) in this setting. MRI is particularly exquisite at evaluating ALVAL and soft tissue complications. It is also very good at detecting osteolysis and other boney complications (as in this case). MRI is my strong preference over CT and Bone Scan for these patients.
1. Gallo J, Kamínek P, Tichá V, Řiháková P, Ditmar R. Biomed. Papers: 2002 – vol. 146 no. 2, pp. 21-28.
2. Hayter CL, Gold SL, Koff MF, Perino G, Nawabi DH, Miller TT, Potter HG. AJR: 2012 – vol. 199 no. 4, pp. 884-893.
3. Yanny S, Cahir JG, Barker T, Wimhurst J, Nolan JF, Goodwin RW, Marshall T, Toms AP. AJR: 2012 – vol. 198 no. 6, pp. 1394-1402.
4. Potter HG, Nestor BJ, Sofka CM, Ho ST, Peters LE, Salvati EA. The Journal of Bone and Joint Surgery: Sept. 2004 – vol. 86-A no. 9, pp. 1947-1954.
5. Potter HG, Foo LF. Orthop Clin N Am: 2006 – vol. 37 no. 3, pp. 361-373.