Post-traumatic patellar tendon ossification in children: a case series

Background. Fractures of the bones that form the knee joint in children are quite rare, accounting for up to 6% of all bone fractures. These include avulsion fractures of the patellar apex as well as tibial tuberosity avulsion fractures, which may result in patellar tendon ossification. Based on literature, the ossification may also occur in cases of primary or chronic (complete or partial) patellar tendon tears. Such a complication is quite rare in pediatric traumatology; it requires differential diagnosis and various surgical tactics.

The aim of the study is to present a clinical and radiological picture of post-traumatic patellar tendon ossification in children and its surgical treatment outcomes using a case series as an example.

Methods. We present a monocenter retrospective series of 4 male patients. Anamnestic, clinical, radiological and histological data were analyzed.

Results. The patients’ mean age was 14 (range, 11-16) years. In all cases, there was a history of trauma. Initially, after getting injured, the patients were treated for a knee injury. In one patient, as a result of his falling on 2 limbs, a bilateral pathology was observed; in other three cases, the pathology was unilateral. Flexion contracture and pain syndrome prevailed in the clinical picture. All patients underwent surgery ranging from excision of ossifications to excision of ossifications with reconstruction of tendon defects and refixation of the tibial tuberosity with osteosynthesis. In all cases, knee joint contracture was eliminated and the volume of movement was fully restored. Histology showed fragments of mature bone tissue represented by thinned bone beams with focal osteoclastic reaction and areas of endochondral ossification.

Conclusions. The clinical picture of pediatric patients with patellar tendon ossification manifests in the form of a chronic cascade of symptoms and functional and topographic disorders: patellar tendon ossification, patella alta, anterior knee pain, flexion contracture and rectus femoris muscle hypotrophy. X-ray and MRI data determine a formation of bone density with uneven clear contours in the projection of the patellar tendon, along with patella alta and the Caton-Deschamps index increasing more than 1.3. The primary treatment method of the developed complication is the surgical one, which leads to the restoration of the full amplitude of movements in the knee joint.