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Updated: Jun 16, 2026
Four-Dimensional CT Analysis Using Sequential 3D-3D Registration
Published on: November 23, 2019
Patellar Tracking: An Old Problem with New Insights
Robert E Watts1, Tetyana Gorbachova1, Russell C Fritz1
1From the Departments of Radiology (R.E.W., A.M.L., R.D.B.) and Orthopaedic Surgery (S.L.S.), Stanford University School of Medicine, 300 Pasteur Dr, Stanford, CA 94305-5101; Department of Radiology, Einstein Healthcare Network and Jefferson Health, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA (T.G.); Department of Musculoskeletal Radiology, National Orthopedic Imaging Associates, Greenbrae, CA (R.C.F.); Department of Musculoskeletal Radiology, Atlantic Medical Imaging, Galloway, NJ (S.S.S.); Department of Radiology, Benning Martin Army Community Hospital, Fort Benning, GA (J.K.); Departments of Radiology and Biomedical Data Science, Stanford University, Stanford, CA (A.S.C.); and Department of Orthopaedic Surgery, Lucile Packard Children's Hospital at Stanford, Palo Alto, CA (K.G.S.).
Abstract:
Patellofemoral pain and instability are common indications for imaging that are encountered in everyday practice. The authors comprehensively review key aspects of patellofemoral instability pertinent to radiologists that can be seen before the onset of osteoarthritis, highlighting the anatomy, clinical evaluation, diagnostic imaging, and treatment. Regarding the anatomy, the medial patellofemoral ligament (MPFL) is the primary static soft-tissue restraint to lateral patellar displacement and is commonly reconstructed surgically in patients with MPFL dysfunction and patellar instability. Osteoarticular abnormalities that predispose individuals to patellar instability include patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Clinically, patients with patellar instability may be divided into two broad groups with imaging findings that sometimes overlap: patients with a history of overt patellar instability after a traumatic event (eg, dislocation, subluxation) and patients without such a history. In terms of imaging, radiography is generally the initial examination of choice, and MRI is the most common cross-sectional examination performed preoperatively. For all imaging techniques, there has been a proliferation of published radiologic measurement methods. The authors summarize the most common validated measurements for patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Given that static imaging is inherently limited in the evaluation of patellar motion, dynamic imaging with US, CT, or MRI may be requested by some surgeons. The primary treatment strategy for patellofemoral pain is conservative. Surgical treatment options include MPFL reconstruction with or without osseous corrections such as trochleoplasty and tibial tubercle osteotomy. Postoperative complications evaluated at imaging include patellar fracture, graft failure, graft malposition, and medial patellar subluxation. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.
