Considerations in spontaneous quadriceps tendon rupture repa
Spontaneous quadriceps tendon rupture (SQTR) is a rare injury to the knee extensor mechanism that is usually associated with systemic diseases such as end-stage renal diseases (ESRD) and it is more prevalent in the elderly. Due to the underlying pathology, quadriceps tendon rupture warrants special considerations and management in its repair.

A 26-year-old male with ESRD due to autoimmune glomerulonephritis on continuous ambulatory peritoneal dialysis (CAPD) for 7 years came to our hospital after a scooter accident. Physical examination showed hematoma and a positive ballottement test of the right knee. Laboratory examination showed increase levels of iPTH, urea (133 mg/dl), creatinine (15,79 mg/dl), phosphate (7,40 mg/dl), and calcium (7,5 mg/dl). His x-ray showed a displaced right patella with suspicion of an avulsion rupture of the quadriceps tendon. MRI of the right knee confirmed a sub-total rupture of the quadriceps tendon with subluxation of the patella. Laboratory parameters and ESRD were controlled by the internal medicine department.

Complete rupture at the insertion site of the tendon on the superior pole of the patella was repaired transosseous using a modified Bunnel technique. Triple Loaded Fiber Suture 5.5 mm PEEK Anchor was used as an internal augment, placed in the middle of the top of the patella. Two vertical holes were drilled with a 2,5 mm drill bit from the superior to the inferior direction in the medial and lateral part of the right patella. Connecting bone surfaces were scraped to produce a rough surface. The central fiber suture is used to directly tie the middle third of the tendon stump, while the two other sutures fixed the medial and lateral third of the stump after re-routing one limb of the sutures through the vertical tunnel on each side. Complete fixation of the quadriceps was finished in 3 sutures using a modified Bunnel technique. The suture was supplemented with overriding stitches. The right knee was immobilized with above-knee long leg casting for 6 weeks, followed by a post-op knee extension brace for another 4 weeks.