PMC6304870_01
(a) Radiograhps, CT scan, and MRI of the left knee at the time of presentation demonstrate varus malalignment with medial sided proximal tibia stress fracture with extension to the articular surface and articular surface collapse. (b) Radiographs, CT scan, and MRI of the right knee demonstrate varus malalignment with medial sided tibia stress fracture without articular collapse.
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MRI of the left knee demonstrated a medial tibial plateau fracture with two millimeters of articular depression and extension of the fracture to the tibial spine (Figure 1(a)). T2 signal surrounded by diffuse hyperintense signal suggesting a medial tibial plateau stress fracture with surrounding bone edema, without articular collapse or extension (Figure 1(b)). These fractures were at the level of the physis, and there was surrounding sclerosis on plain radiographs.
(a) Postoperative radiographs of left knee status post excision, grafting, and open reduction internal fixation left proximal tibia. (b) Postoperative radiographs of right knee status post excision, grafting, and open reduction internal fixation right proximal tibia.
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The patient underwent the aforementioned procedure without complication, and the patient remained nonweight bearing to his bilateral lower extremities (Figure 2(a)). At the six-week follow-up visit after the procedure on his left knee, the patient was still having significant pain in his right lower extremity and, after extensive counseling, elected to undergo the same procedure on the contralateral limb in an effort to return to running and continue his military career (Figure 2(b)).
(a) Left proximal tibia specimen showing fragments of nonossifying hyaline cartilage with admixed fibroconnective tissue consistent with persistent physis (H&E; 200x). Histological examination of the left proximal tibia tissue specimen showed fracture callus comprising mixed chondroid/fibroconnective tissue undergoing ossification. Examination of the right proximal tibia tissue specimen obtained six weeks later demonstrated numerous admixed fragments of purple to purple-gray staining myxochondroid matrix suggestive of chondroid metaplasia, which is not an expected finding in this anatomic location distal to the articular surface. This presence of cartilage at this location is again consistent with a persistent physis. (b) An intraoperative photograph of right proximal tibia status post debridement of fibrous material at the site of prior physis.
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Histology demonstrated nonossifying hyaline cartilage with admixed fibroconnective tissue consistent with a persistent physis (Figure 3(a)). Similar intraoperative pathology specimens were again obtained at the fracture site distal to the articular surface (Figure 3(b)), and these demonstrated fragments of purple to purple-gray staining matrix with chondroid metaplasia.