To describe and illustrate the spectrum of pathological findings related to patellar resurfacing on plain-film X-rays in patients with total knee arthroplasty, regardless of whether the outcome of knee arthroplasty was favorable. To familiarize radiologists with uncommon and often forgotten complications of patellar resurfacing in total knee arthroplasty.

In some knee replacements, the patella is unaltered, and the artificial implant is shaped to glide easily beneath it. But in another approach, called patellar resurfacing, the surgeon attaches a separate piece to the back of the patella to fit smoothly with the implant, resurfacing the patella (Figure 01). Patellar resurfacing is performed in about 45% of patients undergoing total knee arthroplasty. Resurfacing is a good option for obese patients, those with patella baja, and those at risk for anterior knee pain. Isolated patellar resurfacing...

Plain-film X-rays of the knees are standard in the presurgical evaluation of candidates for patellar resurfacing with or without total knee arthroplasty. Baseline postsurgical plain films 3 weeks after the procedure and plain films every 1 or 2 years during long-term follow-up are considered appropriate. Knee plain films are one means of surveillance for possible complications in routine postsurgical follow-up. Routine views of the knee are the anteroposterior, lateral, and tangential axial (Merchant) views. Radiological findings in complications of the patellar button are not very...

Complications of patellar resurfacing following total knee arthroplasty are rare, but often clinically significant. Plain films are essential for the evaluation of patellar resurfacing complications and should be the initial imaging study. Careful attention to initial prosthesis placement and comparison of follow-up images will allow subtle abnormalities to be detected. This information may influence treatment strategy and surgical planning.Radiologists need to be able to recognize these uncommon and often forgotten complications.

• Resurfacing versus not resurfacing the patella in total knee arthroplasty: 4 year results. Bonin N, Mercado J, Deschamps G, DeJour D. Presented at the 13th ESSKA 2000 Congress. May 21-24, 2008. Porto, Portugal. • Patellar resurfacing in primary total knee replacement: a meta-analysis. Pilling RW, Moulder E, Allgar V, Messner J, Sun Z, Moshen A. J Bone Joint Surg Am. 2012 Dec 19;94(24):2270-8. doi: 10.2106/JBJS.K.01257. • Aseptic loosening of the patellar component at the cement-implant interface. Knee. Rath NK, Dudhniwala AG, White SP, Forster...