[Bifocal avulsion of the patellar tendon in an adult: a case report].

PURPOSE OF THE STUDY

Bifocal proximal and distal avulsion of the patellar tendon is a rare event in adults with, to our knowledge, no previous report in the literature. Exceptional bifocal avulsion of the patellar tendon is generally related to an underlying bone or systemic disease. We report the case of a 90-year-old diabetic patient who developed simultaneous avulsions of the patellar and tibial insertions.

CASE REPORT

A 90-year-old woman with noninsulin-dependent diabetes mellitus fell on her left knee and was subsequently unable to extend the knee despite normal quadriceps contraction. Radiographically, the knee joint showed a transverse fracture of the lower third of the patella and a fracture of the anterior tibial tuberosity, evidencing rupture of the quadriceps tendon. Signs of osteoarthritis were minimal. The patient underwent surgery for osteosynthesis of the patella with two vertical pins and a figure-eight wire cerclage in addition to fixation of the anterior tuberosity of the tibia with 3 staples and wire cerclage. The patient recovered well and was walking six months later.

DISCUSSION

Bifocal disruption of the extensor system is a rare event in adults. It is usually associated with an underlying bone disease (Paget's disease, osteomalacia, osteitis deformans) or systemic disease (lupus erythematosus, rheumatoid arthritis, hyperparathyroidism, Wilson's disease), but bilateral spontaneous disruption may occur. There have been two reports of patellar full-thickness tendon tears in diabetic patients but no case of a bipolar avulsion involving both insertions. Concurrent forces applied to the ligament were probably the cause of this unique type of patellar tendon avulsion.

CONCLUSION

This is the first report of a bifocal disruption of the patellar tendon. Different underlying diseases may be involved. Treatment consists in double fixation.