In 1856, Monro first reported osteochondral free bodies in the ankle joint. 1888, König used the term exfoliative osteochondritis to describe free bodies in the knee joint. 1922, Kappis referred to a similar lesion in the ankle joint as exfoliative osteochondritis. 1959, Berndt and Harty described in detail a case of osteochondral injury of the talus, based on x-ray presentation and called it exfoliative osteochondritis. In 1959, Berndt and Harty described in detail cases of osteochondral damage of the talus, staged according to the radiographic presentation, and called it exfoliative osteochondritis of the talus. In later literature, these diseases were also referred to as osteochondrosis of the talus, transchondral talar fracture, and occult osteochondral fracture, and are now mostly referred to as osteochondral injuries of the talus. Etiology】 The etiology is not completely clear, and the mechanism is similar to that of exfoliative osteochondritis of the knee joint, which may be related to the following factors. 1, trauma Berndt and Harty believe that ankle inversion injury is the cause of osteochondral injury of the talus. Through the study of cadaveric specimens, it was found that in ankle dorsiflexion inversion injury, the lateral part of the talar carriage impinges on the external ankle joint surface, resulting in anterolateral talar osteochondral injury; in ankle plantarflexion inversion injury, the medial part of the talar carriage impinges on the tibial joint surface, resulting in posterior medial talar injury. However, some patients do not have an obvious history of trauma. 2. Ischemia Campbell and Ranawat believed that exfoliative osteochondritis of the talus is due to localized subchondral bone ischemia and necrosis, producing pathological osteochondral fractures. Injury pathology】 The lateral lesion is mostly located in the anterior middle 1/3 of the articular surface, with a shallow saucer shape, and the osteochondral block is easily displaced; the medial lesion is mostly located in the middle and posterior 1/3 of the articular surface, with a cup shape, and the osteochondral block is not easily displaced. Pathological sections showed that the articular chondrocytes on the surface of the osteochondral mass were usually degenerated but still alive, while the bony part showed necrosis. The synovial membrane of the joint shows inflammation and hyperplasia. Diagnosis】 1. Symptoms The main symptoms are pain and swelling of the ankle joint under weight, which is aggravated after exercise. The pain is diffuse and has no clear localization. Some patients have symptoms of joint interlocking. 2. Signs There are no obvious signs in the early stage. In severe cases, the joint is swollen, the mobility is reduced, and there is pressure pain in the medial or lateral joint space due to inflammation and hyperplasia of the synovial membrane, and there is a feeling of sand when flexing and extending. Berndt and Harty classified the injury into 4 stages according to the X-ray performance. A study by Verhagen et al. found a 41% missed diagnosis rate with a sensitivity and specificity of 0.59 and 0.91, respectively, on plain X-rays. X-ray staging (Berndt and Harty) Staging X-ray presentation I Limited hypodense area at the apex of the talus (subchondral bone compression) II Partial separation of the osteochondral mass and the bone bed III Complete separation of the osteochondral mass and the bone bed without displacement IV Complete separation of the osteochondral mass and the bone bed with displacement (2) CT: Studies have shown that the specificity of spiral CT can reach 0.99 and the sensitivity is slightly lower, up to 0.81. Treatment】 1. Conservative treatment includes rest, plaster fixation, partial weight-bearing of the affected limb for 6-8 weeks, etc. It is usually applied to adolescents with unclosed epiphysis and patients whose x-ray staging belongs to stage I or II. However, a study by Letts et al. found that conservative treatment was not effective in adolescent patients, with only 9 out of 24 patients having good results. The results were poor in adult patients and in patients whose x-ray staging fell into stages III and IV. Some studies have shown that the success rate of conservative treatment for adult patients is 45% by changing exercise patterns, partial weight-bearing or cast immobilization. 2.Surgical treatment Patients with X ray stage I or II and MRI stage I should be operated if conservative treatment is not effective. patients with X ray stage III or IV and MRI stage II should be operated as soon as possible. (1) Arthroscopic surgery: This includes arthroscopic debridement of the lesion alone and arthroscopic debridement of the lesion with microfracture (or drilling). The advantage is that the surgery is less invasive, the postoperative recovery is fast, and the treatment of small area of talar cartilage injury is effective, with an excellent rate of 83% to 93%. The disease can be graded according to the arthroscopic presentation of the cartilage injury. MRI staging of talar osteochondral injury (Cheng) Grading Arthroscopic presentation A smooth, intact surface of articular cartilage, but markedly softened B rough surface of articular cartilage C fibrotic or fissured articular cartilage D flap-like injury of articular cartilage, or exposure of subchondral bone E osteochondral free body, but not displaced F displaced osteochondral free body (2) Incisional surgery 1) Traditional ankle incision and lesion cleaning (1) Conventional ankle dissection and lesion cleanup: The excellent rate is 40% to 62.5%. It is usually necessary to do internal or external ankle osteotomy, which is traumatic and requires several weeks of postoperative plaster fixation, which is not conducive to the patient’s early return to normal life and work. (2) Autologous osteochondral transplantation or chondrocyte transplantation: For cases with poor results of arthroscopic lesion cleanup plus microfracture, cases with large damage to the talar osteochondral bone (>2cm2) or cases with deep bone cysts, autologous osteochondral transplantation or chondrocyte transplantation can be tried, and the excellent rate can reach 90%.