Fig. 1

A On MRI and CT, we could see that the destruction of the articular surface of patient A was much less than 50% of the total articular surface (red arrow). The destruction of the articular surface was not obvious. In this case, we believed that the postoperative joint function would not be greatly affected. So we chose the surgical procedure, ‘triple clear’ (TC). At 3 years after surgery, we could see that the patient’s joint morphology was basically the same as that before surgery, and no obvious postoperative arthritis was observed. In the areas where there was the destruction of the articular surface before surgery, obvious autogenous bone repair response could be seen (A’). B All the articular surface of the femur lateral condyle in the patient B was destroyed. The overall range of the damage exceeded 50% of the total articular surface (yellow arrow). At this point, we believed that segmental resection with prosthesis reconstruction was the only option. C We could see that patient C had a fairly large lesion, which even broke through the interosseous compartment. It was graded as Companacci III. However, the destruction of the articular surface was not more than 50% of the overall articular surface (green arrow). In this case, we also chose the TC. At 2 years after surgery, we could see that the patient’s joint morphology was consistent with that before surgery, and no obvious manifestations of arthritis or joint collapse were observed. The subchondral bone repaired obviously. The bone density of the residual cavity also increased significantly (C’)