| September 2005 Case of the Month |
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Compiled By: Floriece Blackmon, M.D.
History: 16-year-old female with pain under the patella for 9 months, worse with running and climbing stairs.
Findings: (Images1/2) axial T2/sagittal T1 images. A focus of intermediate signal intensity and tendon thickening are seen in the proximal central patellar tendon.
(Images 3/4) PD SPIR/CT2 SPIR; hyperintense signal in the proximal posterior fibers of the patellar tendon with associated small partial tendon tear and mild peritendinitis.
Diagnosis: "Jumper's Knee"
Discussion: The spectrum of “jumper’s knee” includes patellar tendinopathy, patellar tendinosis and patellar tendon tear. The term “tendinopathy” refers to painful overuse tendon conditions without implying pathology and is ideal for clinical diagnosis. “Tendinitis” implies an inflammatory pathology and is a misnomer in view of the fact that the chronic painful tendon conditions are devoid of inflammatory cells. The key pathology is tendinosis with collagen degeneration and its sequelae.
Presenting symptoms of jumper’s knee are anterior pain in patients participating in high-risk sporting activity (basketball, volleyball, etc.). The pain and tenderness usually are in the area of the patellar tendon, at the inferior pole of the patella. Stiffness, grinding, and swelling of the knee may have been present for a long period of time.
Early in the process, there is hypointense edema of the peritenon without visible change in the tendon on T1-weighted images. Subsequently, focal thickening of the patellar tendon with preferential involvement of the medial and central portions of the tendon, and areas of intermediate to hyperintense signal intensity of the tendon are present on MR images. These signal changes are most apparent on T2WI and T2* GRE MRI. A partial tear of the patellar tendon, as in this case, may develop in advanced cases.
Differential diagnosis includes: magic angle artifact. The patient is asymptomatic, increased signal intensity seen at T1WI is not identified on T2WI.
Conservative treatment (e.g. strengthening exercises, load reduction, and massage) is the management of choice.
Surgery is considered only after an appropriate conservative treatment has failed.
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References:
- Stoller, DW, Tirman PFS, Bredella MA Diagnostic Imaging; Orthopaedics, Salt Lake City, Amirys, 2004.
- YU JS, Popp SE, Kaeding CC, Lucas J. Correlation of MRI imaging and pathologic findings in athletes undergoing surgery for chronic patellar tendinitis, AJR 1995; 165: 115-118.
- McCloughlin RF, Rober EL, Vellet AD, Wiley JP, Bray RC. Patellar tendonitis; MR imaging features with suggested pathogenesis and proposed classification. Radiology 1995; 197: 843-848.
- Khan KM, Cook JL, Taunton JE, et al: Overuse tendinosis, not tendonitis; a new paradigm for a difficult clinical problem. Phys Sportsmed 2000: 28 (5); 38-48.
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