Original Article

HSS Journal ®

, Volume 8, Issue 2, pp 92-95

First online:

MRI Diagnosis of Patellar Clunk Syndrome Following Total Knee Arthroplasty

  • Thomas J. HeyseAffiliated withDepartment of Orthopedics and Rheumatology, University Hospital Marburg Email author 
  • , Le Roy ChongAffiliated withHospital for Special Surgery
  • , Jack DavisAffiliated withHospital for Special Surgery
  • , Steven B. HaasAffiliated withHospital for Special Surgery
  • , Mark P. FiggieAffiliated withHospital for Special Surgery
  • , Hollis G. PotterAffiliated withHospital for Special Surgery

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Patellar Clunk Syndrome is a painful condition associated with a mechanical catching or clunking during active extension following total knee arthroplasty (TKA). The syndrome is caused by growth of interposing soft tissue usually at the superior pole of the patella. This interposed soft tissue cannot be visualized on plain radiographs.


The aim was to ascertain if magnetic resonance imaging (MRI) would prove helpful in confirming the clinical diagnosis of patellar clunk by visualizing the interposed soft tissues adjacent to the patella and that the recognition of this tissue would be highly reproducible.


MRI scans of 12 patients with clinical suspicion or related symptoms of a patellar clunk syndrome following primary TKA were retrospectively evaluated. Size of soft tissue masses proximal to the patella were determined in sagittal and axial MRI views. Largest diameters were recorded in two dimensions by two independent observers, and interobserver reliability was determined by intra-class correlation coefficients (ICC).


Nine patients (75%) showed obvious MRI findings consistent with a patellar clunk lesion with high interobserver reliability (ICC values >0.75). In eight patients, this lead to operative treatment with arthroscopic debridement.


MRI helps confirm the clinical diagnosis of patellar clunk. The data indicate that MRI is effective in defining the soft tissue lesion that is implicated in clinically evident patellar clunk syndrome after TKA.


patellar clunk TKA MRI total knee arthroplasty magnet resonance imaging