Patellar tendonitis.

A 51-year-old female with a history of gout, hypertension and diabetes presented to the emergency department with one week of increasing pain and swelling of her left knee, just below the patella. She denied trauma, fever and calf pain. She took Ciprofloxacin for 14 days for a urinary tract infection. She was afebrile with stable vital signs, and the exam revealed mild swelling, increased warmth, and tenderness overlying the left tibial tuberosity. There was full range of motion at the knee. A bedside ultrasound (US) confirmed the diagnosis (Figure 1 and 2).

Figure 1.

Dark, anechoic areas within the tendon and surrounding the tendon bundle represent fluid from inflammation (red arrows).1,2

Figure 2.

Normal patellar tendon appears as a tightly packed, fibrillar tissue bundle represented by bright, hyperechoic parallel lines (red arrow) which attaches to the tibial tuberosity.1,2

Patellar tendonitis (PT) is characterized by well-localized anterior knee pain, along the patellar tendon distribution. The pain is often exacerbated by moving from sitting to standing or walking uphill.3 Causes of PT include repetitive use, jumping sports, trauma and fluoroquinolone use.3 Fluoroquinolone-associated tendinopathy and tendon rupture occurs days to weeks after starting the medication.4 The risk increases in the following patients: older than 60 years, taking steroids, renal disease and recipients of kidney, heart, or lung transplants.4

Bedside US can be used to evaluate musculoskeletal injuries, including fracture, dislocation, joint effusion and tendon tears.5 A high frequency linear transducer was used first in longitudinal plane, placed over the tibial tuberosity evaluating the patellar tendon and then laterally in transverse plane evaluating for joint effusion. It illustrated absence of knee joint effusion and presence of inflamed patellar tendon. This patient was instructed to stop taking Ciprofloxacin, and was treated with anti-inflammatory pain medications and rest.