In patients with chronic renal failure, many complications may develop that involve all organ systems, especially the locomotor system. Spontaneous concurrent bilateral rupture of the quadriceps tendons is a very rare complication in patients with chronic renal failure, usually occurring in patients under 50 years of age. Although there are numerous causes that lead to tendon weakness and rupture, most authors agree that secondary hyperparathyroidism plays a major role in the pathogenesis of tendon rupture. Soft tissue and perivascular calcifications, diminished local circulation, reduced tendon elasticity, impaired collagen metabolism, nerve lesions, repeated trauma, and articular swelling contribute to tendon weakness and rupture. A patient is presented in whom spontaneous concurrent bilateral quadriceps tendon rupture occurred at the age of 34, after seven years of hemodialysis therapy. Timely diagnosis and operative management with primary tendon suturing followed by physiotherapy produced a good anatomical and functional result.

In this study, we present a case of a very rare and large suprapatellar synovial cyst of the knee, which was successfully treated with an arthroscopic intra-articular decompression. Suprapatellar bursa is located between the femur and quadriceps tendon, proximal to the knee joint, and it normally communicates with a joint cavity. However, very rarely bursa can remain completely separated from the knee joint, which can result in the formation of a separated compartment inside which, in special circumstances, fluids can be accumulated and with time can lead to the formation of suprapatellar cyst. Although certain authors use ultrasound, arthrography and computerized tomography, MRI is recognized as the 'gold standard' in diagnostics of knee cysts. When considering ways of treatment, according to the available literature, suprapatellar cysts are treated mostly by an open excision, whereas in our case we managed to show that cysts could also be effectively and safely treated by arthroscopic decompression, with no recurrence and followed by fast and functional recovery.