Introduction: The most frequent procedure in treatment of acute or chronic anterior cruciate ligament (ACL) rupture is the so called bone-tendon-bone reconstruction. A transverse dislocated patella fracture is a rare complication of this procedure with an incidence of 0.23%-2.3%. In a five year period, (1998-2002), 407 arthroscopic reconstructions of the anterior cruciate ligaments were done at our Clinic, and there was only one case of patella fracture.
Case report: An 18-year-old female patient, a handball player, suffered an acute rupture of anterior cruciate ligament of the left knee, so arthroscopic bone-tendon-bone reconstruction of the anterior cruciate ligament was performed. After adequate skin incision, a bone graft was taken from the patella and upper part of trapezoid tibia, which was 25 mm long, 10 mm wide and 5 mm thick, together with a part of patellar ligament. After the remains of the anterior cruciate ligament had been arthroscopically removed, tunnels were made in tibia and femur and a graft was inserted and fixed with two metal interference screws. Knee stability was tested, and drainage was put in the knee joint. The wound was closed by layers. The quadriceps exercises and passive knee movements started immediately. Full range of movements was accomplished six weeks later when the patient started to walk with full weight-bearing on her operated leg. Three weeks later, (nine weeks after the operation), the patient has accidentally lost her balance and fell. A transverse, dislocated fracture of the left patella was diagnosed and osteosynthesis of the fractured patella with two Kirschner wires and a metallic loop was performed. Postoperatively, full range of movement was allowed. Six months later, the patient felt no pain, there was no swelling, full range of knee movement was achieved, while the Lachman Test was identical in both knees and the pivot shift test was negative.
Discussion: Fracture of patella after ACL reconstruction is due to several reasons: size and shape of the graft, technique of its taking, disturbed patellar blood supply, incomplete filling of patella defect after graft taking, and inappropriate postoperative rehabilitation. If a patellar fracture occurs after anterior cruciate ligament reconstruction, the best treatment is firm osteosynthesis, which enables bone healing and immediate continuation of the previously resumed rehabilitation program. However, this complication prolongs the rehabilitation period and slows down return to sports.