We describe a case of a patient who presented with recurrent localized pain of the left patella. There was no history of direct trauma.
The patient presented with recurrent localized pain, tenderness, swelling and restricted motion of the inferior pole of the left patella. Past history: tophi in the first metatarso-phalangeal joint of the left foot one year ago and family history of crystal-induced arthropaties-gout. Ultrasound, radiography and MR were performed. US revealed thickened and hyperechoic patellar tendon with well-defined acoustic shadowing by calcifications inside and the extension into soft tissue, especially in the proximal portion; acoustic shadowing was reported along the inferior pole of the patella. Lateral x-ray film showed the well defined calcifications. Proximal patellar tendon and inferior pole of the patella in MR examination appeared hyperintense on T1,T2, PD and STIR weighted images; all images revealed an increased AP diameter of the tendon and foci of signal voids inside it.
Gout is a hereditary metabolic disorder. The biochemical hallmark of the disease is hyperuricemia, which develops in response to an excessive rate of production of uric acid, a decrease in renal excretion of uric acid, or a combination of the two. Traditionally gout has been classified into two types: primary gout, in which the underlying hyperuricemia is the result of an inborn error of metabolism, and secondary gout, in which hyperuricemia is a consequence of any of a number of other disorders. Idiopathic gout occurs far more frequently in men than in women. The first attack of arthritis appears most often during the fifth decade of life in men and in the postmenopausal period in women. Microcrystals of sodium urate are capable of evoking an acute inflammatory response in the skin, subcutaneous tissues, and joints. In chronic tophaceous gout, urate deposition occurs in the articular cartilage, subchondral bone, synovial membrane, capsular tissues and tendons. Gout produces asymmetric polyarticular involvement. It affects predominantly feet, hands, wrists, elbows and knees. Radiographic manifestations occur late in the course of the disease and include lobulated eccentric soft tissue masses, intra-articular and extra-articular bone erosions, relative preservation of the joint space, subperiosteal apposition of bone, intraosseous calcification, and secondary degenerative alterations. Osteoporosis generally is lacking. Patellar tendon and prepatellar soft tissue swelling also may be evident. Other conditions associated with patellar tendinopathy are: rheumatoid arthritis, psoriatic arthritis, septic arthritis, iatrogenic causes (steroid therapy, fluoroquinolone treatments, etc.), diabetes mellitus, calcium pyrophosphate dehydrate deposition, xanthomatosis. In our case, the diagnosis of rheumatoid arthritis was rejected because it produces symmetric joint involvement, fusiform soft tissue swelling, and regional osteoporosis. Septic arthritis hypothesis was discarded because our patient wasn’t infected. Psoriatic arthritis was rejected because there wasn’t periosteal proliferation at the margins of the joint, and no involvement of sacroiliac joints. Although the radiographic manifestations of Calcium Pyrophosphate Dehydrate Crystal Deposition Disease may resemble those of gout, the presence of lobulated soft tissue masses, intact joint spaces, and osseous erosions in the latter disease permitted differentiation of the two disorders. The hypothesis of xanthomatosis was discarded because hypercholesterolemia wasn't present in our patient. Clinical history of the patient, physical examination, laboratory tests and imaging features suggested a diagnosis of gouty tendinitis.
Patellar tendinitis in gouty arthritis
1. From the left knee X-ray:
• Localized soft tissue swelling around the left patella (patellar tendon/prepatellar soft tissue) with relatively clear margins, and suspicious abnormal density or increased density within.
• The joint space generally appears acceptable without remarkable signs of narrowing.
• No significant generalized osteoporosis is seen; there is a suspicious mild bony destruction or marginal erosion in the local area.
2. Ultrasound imaging shows:
• Inhomogeneous echogenicity of the patellar tendon region, with local tissue thickening or calcific deposits (hyperechoic areas), and irregular local structure.
• Abnormal localized echo on the patellar surface; an irregular interface is visible at the attachment with the patellar tendon.
3. MRI findings:
• On T1/T2-weighted images and fat suppression sequences, there is a localized abnormal signal focus within the patellar tendon and prepatellar soft tissue, presenting a mixed or heterogeneous high-/intermediate-signal intensity.
• No apparent large effusion in the joint space; the articular cartilage is basically intact, with localized inflammatory changes in the surrounding soft tissues.
• No obvious signs of meniscal or ligament rupture or severe tear.
Based on the above imaging and the patient’s history (56-year-old male with recurrent patellar pain), the following possibilities are considered:
Considering the middle-aged male, possible hyperuricemia (gout), imaging findings of soft tissue swelling and localized bony erosions, and ruling out other inflammatory arthropathies and infection, the most likely diagnosis is gouty inflammatory changes (gouty patellar tendinitis / tendinopathy).
1. Medications and General Management:
• Control of Elevated Uric Acid: Consider the use of allopurinol or febuxostat and adjust according to serum uric acid levels.
• Relief of Acute Pain and Inflammation: During acute flares, nonsteroidal anti-inflammatory drugs (NSAIDs) or colchicine may be used. Short-term low-dose corticosteroids may be considered if necessary.
• Lifestyle Management: Adhere to a low-purine diet, avoid excessive alcohol or sweetened beverages, maintain adequate hydration, and focus on weight management.
2. Rehabilitation Training and Exercise Prescription (FITT-VP Principle):
• Frequency: Recommend 3–5 sessions per week, adjusted according to the severity of joint symptoms.
• Intensity: Start with low intensity (e.g., light stationary cycling, lower extremity range-of-motion exercises) and gradually progress to moderate intensity. Avoid excessive impact or heavy loading to prevent aggravation of patellar tendinopathy.
• Time: Begin with 15-minute sessions and gradually increase to 30 minutes or more based on individual tolerance, especially in the later subacute phase or stable phase.
• Type: Low-impact aerobic exercises such as swimming, stationary cycling, or elliptical training, combined with small-range resistance exercises (e.g., elastic band ankle presses, half-squat practice).
• Progression: As inflammation subsides and joint function recovers, progressively add lower-extremity strength and stability training, such as isometric quadriceps exercises, then transition to closed-chain and open-chain resistance training.
• Precautions: In the event of an acute gout flare, restrict or pause strenuous activities. Gradually resume once symptoms improve. Monitor pain and swelling closely to avoid further joint injury.
Disclaimer: This report is based solely on the provided medical history and imaging data and serves as a reference for analysis. It cannot substitute an in-person consultation or professional medical advice. For any concerns or changes in condition, please seek medical attention promptly and follow the guidance of a specialist.
Patellar tendinitis in gouty arthritis
