An 11-year-old male presented to clinic with a large anterior bony prominence just distal to the tibial tubercle of his right knee. The patient was athletic and recently began experiencing pain over his proximal tibia with physical activity. Approximately 4 years prior, the patient presented to another orthopedic surgeon with concern about the bony prominence. He was diagnosed with severe OSD and an MRI demonstrated chronic osteochondrosis distal to the tibial tubercle with an overlying bursa. The patient was treated conservatively at that time without resolution of the prominence.
On physical examination, the prominence was not tender to palpation. Full and painless range of motion was observed for the hip, knee, ankle, and toes, and sensorimotor function was intact distally throughout the lower extremity. X-ray demonstrated a possible osteochondroma of the proximal right tibia (Figure 1A and B). MRI confirmed the diagnosis and revealed that the patellar tendon partially inserted on the osteochondroma as well as the tibial tubercle (Figure 2A and B). Given that the mass appeared to be growing in size and the patient was progressively symptomatic, it was decided that surgical excision would be the most appropriate treatment (Figure 3).
A total resection of the mass was performed using an anteromedial approach. An incision spanning 3 inches was made. Local soft tissue from the proximal tibia was dissected. A dissection was also performed on the portion of the patellar tendon that was attached to the anterior tibial mass. The mass was demarcated using a combination of anatomic parameters and C-arm fluoroscopy while taking care not to violate the physis. The mass was resected with a combination of osteotomes and a rongeur. Bleeding was mitigated with bone wax and cautery. The distal insertion of the patellar tendon was then reattached to the bone of the tibia with a suture and anchor technique. The repair was evaluated with motion of the patella, which was found to be excellent and stable. Patellar height was found to be equivalent compared to the contralateral side. Wound irrigation and closure were followed by a sterile dressing and a brace that was locked in extension. Dimensions of the resected mass were 5.0 cm x 4.0 cm x 2.0 cm (Figure 4A). Pathology confirmed that the mass was a benign osteochondromatous proliferation, with irregular architecture and immature cartilage giving rise to disorganized woven bone (Figure 4B and C). Additional areas of reparative changes were suggestive of fracture callus. These histopathology findings were distinct from those expected in OSD, although OSD also presents with changes in fibrocartilaginous tissue.
Postoperatively, the patient was instructed to abstain from athletics for 8 to 10 weeks. At his 2-week postoperative visit, the patient was observed to be compliant with non-weightbearing and mobilizing with a wheelchair. Range of motion in the knee brace was increased, and the patient was permitted to toe-touch. Given that the patient had difficulty adjusting to crutches, physical therapy was prescribed to increase weight-bearing capacity. At the 5-week follow-up, the patient had intact straight leg raise and was able to bear weight as tolerated in the brace. Range of motion in the knee brace was subsequently increased from 0  to 90 . At the 8-week follow-up, knee range of motion was 0  to 120  without discomfort. Bracing was discontinued given that the patient was observed to bear weight as tolerated and the radiographs showed no concern for fracture (Figure 5A and B). The patient was instructed that he may resume some sports activities (eg, shooting baskets) but should avoid competitive or gym activities until fully cleared. At the 16-week follow-up, range of motion further increased to 130  without discomfort, and the patient was instructed to resume activities. At the 19-month follow up, patient had full resumption of athletic activities and experienced minimal pain. Radiographs demonstrated progressively healing tissue in surgical site evident by remodeling in the area of the lesion inferior to the tibial tubercle (Figure 6A-C). Clinical examination showed fully healing of the incision without any recurrence of the anterior mass (Figure 7). The patient's PEDI-IKDC   score at approximately 19-month post-operatively was 94.6.