Osteochondral injury of the talus is a limited osteochondral injury of the talar talus slide that manifests as localized articular cartilage exfoliation with involvement of the deep subchondral bone. As early as 1959, Berndt and Harty described in detail cases of exfoliative osteochondritis of the talus, staged the disease based on the radiographic presentation, and studied the mechanism of injury. In the later literature, exfoliative osteochondritis of the talus was also referred to as osteochondrosis of the talus, transchondral talar fracture, and occult osteochondral fracture. Because these diseases are difficult to distinguish in terms of symptoms, signs, and imaging manifestations, and because the principles and methods of treatment are basically the same, they are now mostly referred to as osteochondral injuries of the talus. Usually, conservative treatment of osteochondral injuries of the talus is not effective, and the traditional incisional surgery usually requires an internal or external ankle osteotomy to expose the osteochondral injury at the top of the talus, which is highly traumatic, with slow postoperative recovery and more complications, affecting the efficacy. With the development of minimally invasive technology, arthroscopic technology has been routinely applied to the treatment of osteochondral injuries of the talus in foreign countries. In contrast, the domestic start in this area is late, and no published literature reports have been seen yet. In this study, we summarized and analyzed the symptoms, signs, imaging manifestations, minimally invasive arthroscopic surgical methods and surgical efficacy of 34 patients with osteochondral injuries of the talus admitted to our clinic from January 2000 to December 2005. Data and methods I. Clinical data The 34 patients with osteochondral injury of the talus in this group were 21 males and 10 females, with an average age of 31 years (14 to 56 years), of whom 6 were athletes. The time interval from the appearance of symptoms to the consultation was 1 day to 12 years. Among the 34 patients, 28 had a clear history of trauma, including 20 cases of internal derangement, 4 cases of external derangement, 1 case of external rotation, and 3 cases of unspecified sprain; 6 cases had no clear history of trauma. The symptoms of all patients were pain in the ankle after weight-bearing and walking, and the pain was aggravated after running and jumping; five of the patients had interlocked ankle joints. Physical examination revealed varying degrees of swelling in the ankle joint, and there could be pressure pain in the joint space, and some patients had a grinding sensation when flexing and extending the ankle joint. All 34 cases underwent preoperative frontal and lateral radiographic examination of the ankle joint. 13 cases showed no abnormalities, while 21 cases showed signs of osteochondral damage of the talus. The radiographic manifestation of osteochondral injury of the talus was a hypodense area or exfoliated osteochondral mass at the apex of the talar talus; Berndt and Harty classified the disease into 4 stages according to its radiographic manifestation. Two cases were stage I, five cases were stage II, 11 cases were stage III, and three cases were stage IV. The MRI of the ankle joint can clearly show the focal point of osteochondral injury of the talus, with a well-defined low-signal area under the talar cartilage on T1-weighted images and a high-signal area on T2 images; it can also show whether the surface articular cartilage is intact, whether there are cysts in the subchondral bone, and whether there are separated osteochondral blocks. The treatment should be surgical if the conservative treatment in stage I is ineffective, and surgical treatment should be performed in all stage II. In our group, all 34 cases underwent ankle MRI before surgery, 6 cases were stage I and 28 cases were stage II. All 34 patients underwent ankle arthroscopy (6 patients with stage I MRI were not treated with rest, no weight-bearing or partial weight-bearing on the affected limb for 6 weeks). The surgery was performed using intra-lumbar anesthesia, with the patient in the supine position and a tourniquet at the root of the affected thigh at a pressure of 300 mm Hg. A 30° diameter 4.0 mm arthroscope was used, with anteromedial and anterolateral approaches to the ankle joint. Arthroscopic findings revealed varying degrees of inflammatory hyperplasia in the synovial membrane of the ankle joint in 34 cases. A total of 29 cases of talar osteochondral injury were located medially and 5 cases laterally; the area of injury ranged from 7 mm×7 mm to 20 mm×15 mm. According to the grading criteria of arthroscopic talar osteochondral injury by Cheng et al, there were 2 cases of grade B, 4 cases of grade C, 13 cases of grade D, 11 cases of grade E, and 4 cases of grade F. The total number of cases of grade D and E was 22, accounting for 71% of the total number of cases. In 11 cases, simple lesion debridement was performed, including excision of the hyperplastic synovial membrane, removal of the free body, removal of the unstable cartilage at the edge of the lesion with a cartilage scraper, and debridement of the degenerated calcified cartilage on the surface of the talar bone bed. 5 cases were debridement with drilling, using a 2-mm diameter Kirschner needle perpendicular to the talar bone bed at a depth of 5 mm and a spacing of 3 mm. The ankle should be placed in plantar flexion and a special microfracture instrument should be used to make a hole in the talar bone bed.18 For lesion debridement with microfracture, the tip of the microfracture instrument is drilled perpendicular to the talar bone bed with a depth of 5 mm and a spacing of 3 mm.18 After drilling or microfracture, the tourniquet can be loosened to check if the depth is adequate. If there is blood oozing from the bone hole, the depth of the hole is appropriate; if not, the hole needs to be deepened. After surgery, the affected limb is wrapped with thick cotton pads under pressure, and no drainage is placed in the joint. The affected limb should not be weight-bearing for 8 weeks after surgery, and ankle flexion and extension exercises should be started in the third week after surgery. Patients could resume daily activities and gradually start sports 3 months after surgery. Results We followed up 31 patients from 12 months to 59 months with a mean of 28 months. The preoperative American Foot and Ankle Surgery (AOFAS) hindfoot score (AHS) was 70.9±7.6 (34-75); postoperatively, 90.8±9.4 (65-100). The mean postoperative improvement was 19.9 points compared with the preoperative one, which was statistically different (t test, t = 9.147, P = 0.000); the postoperative score was higher than 80 in 24 cases (above 80 points was considered excellent), and the excellent rate was 87.1%. The subjective pain level score (VAS scale, 0-10 points) was 7.5±1.3 (5-10 points) before surgery; 2.4±2.3 (0-9 points) after surgery; the average decrease of 5.1 points after surgery compared with that before surgery was statistically different (t test, t = 10.853, P = 0.000). The results of the subjective patient satisfaction survey were excellent in 15 cases, good in 12 cases, fair in 3 cases, and poor in 1 case; the excellent rate was 87.1%. There were no postoperative complications such as wound or joint infections or deep vein thrombosis in the lower extremities in any of the 34 cases in this group. Discussion The etiology of osteochondral injury of the talus is unclear and may be related to trauma and ischemia. In our group, 28 cases (82.4%) had a history of trauma, which is similar to the ratio of 75%-92% reported in the literature. Since there are no specific symptoms and signs of osteochondral injury of the talus, the diagnosis mainly relies on imaging examination. In 38.2% (13/34) of the cases in this group, no abnormalities were seen on X-ray, but the osteochondral injury of the talus was detected by MRI, which was further confirmed by arthroscopic surgery. a study by Verhagen et al [3] found that the rate of missed diagnosis on plain X-ray was 41%, with sensitivity and specificity of 0.59 and 0.91, respectively; the sensitivity and specificity of spiral CT were 0.81 and 0.99, respectively; and the sensitivity and specificity of spiral CT were MRI is not only able to reduce leakage and improve the accuracy of diagnosis, but also can accurately show the location, scope and nature of the lesion, which helps in the selection and formulation of treatment plans. MRI can help in the selection and development of treatment plans. The traditional view of Berndt and Harty is that anterolateral injuries are closely related to trauma, have severe symptoms, and have a poor prognosis, whereas posterior medial injuries are not related to trauma, have mild symptoms, and have a good prognosis. However, some studies have shown that there is no significant difference between posterior medial and anterolateral injuries in terms of trauma history and prognosis, and that the main factors affecting the prognosis of osteochondral injuries of the talus are the age of the patient (i.e., whether the epiphysis is closed) and the condition of the surface cartilage, respectively. Adolescent patients with unclosed epiphyses and patients with intact articular cartilage surface (only softening) have a better prognosis and usually do not require surgical treatment. In this group, there were 29 cases of medial talar injuries (85.3%) and 5 cases of lateral injuries (14.7%). 77% of the injuries in Ming et al.’s study were medial to the talus and most of the injuries in Schuman et al.’s study were also medial, while Pettine et al. found that lateral injuries accounted for the majority of injuries; some other scholars found the same percentage of medial and lateral injuries. In Ming et al.’s study, the postoperative AHS score was 92.1 in the lateral injury group and 93.7 in the medial group, and there was no statistical difference between the two groups. The mean postoperative AHS score was 90.3 in the medial group and 95 in the lateral group in this study. Because of the small number of the lateral group, it was difficult to perform a statistical analysis of the effect of injury site on prognosis. Conservative treatment of osteochondral injuries of the talus includes rest, partial weight-bearing of the affected limb, or cast immobilization, and is usually indicated for adolescents and for patients whose x-ray staging falls into stage I or II. However, the 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 success rate of conservative treatment in adult patients was 45% through changes in motion, partial weight bearing, or cast immobilization . The excellent rate of traditional ankle arthrotomy and lesion debridement is between 40% and 62.5%. However, due to the large damage, it is usually necessary to do an osteotomy of the inner or outer ankle, which requires several weeks of postoperative cast fixation, which is not conducive to the patient’s early return to normal life and work. Arthroscopic surgery has gradually become the main method of treating osteochondral injuries of the talus due to its low trauma, relatively simple operation and excellent results. The literature shows that arthroscopic lesion cleaning alone, or arthroscopic lesion cleaning plus microfracture (or drilling) for small osteochondral injuries of the talus have good results, with excellent rates of 83%-93%. The subjective and objective excellent rates in this study were 85.6%, which is similar to the results reported above in the literature. Because the degenerated cartilage on the surface of the bone bed is not conducive to the healing of articular cartilage, care should be taken to remove all the degenerated cartilage on the surface of the subchondral bone bed when performing lesion cleaning, which will achieve better results. In addition, it is not suitable to perform drilling or microfracture when the cartilage damage is mild and the subchondral bone is not exposed, but only to perform focal debridement; osteochondral grafting can be performed when the subchondral bone is obviously damaged and the damage is large and deep; in the rest of cases, the subchondral bone should be drilled or microfractured after the focal debridement to promote cartilage repair. When performing the procedure, care should be taken to place the tip of the kerf or microfracture instrument perpendicular to the subchondral bone surface of the talus and at a sufficient depth (5 mm deep, with blood exuding from the bone hole after relaxing the tourniquet). Compared with the traditional drilling technique, the microfracture technique has gradually replaced the former because it does not produce thermal damage, allows easier management of the posterior talar lesion, and facilitates the attachment of the repair tissue. In this study, there were four cases with poor outcomes: one basketball player, one amateur sportsman, and two general employees. The one case with poor outcome was an amateur sportsman, who showed no relief of ankle pain and increased pain during flexion and extension activities after surgery. The second arthroscopic exploration was performed 18 months after the operation after the treatment with topical joint wash and non-steroidal anti-inflammatory drugs failed. During the operation, it was found that the talar osteochondral injury had been covered by fibrous cartilage tissue, but the local cartilage was significantly overgrown and the normal joint space had almost disappeared. The overgrown cartilage tissue was removed with a planing knife, and the pain was relieved postoperatively. The literature reports that for cases with poor results of arthroscopic lesion cleaning plus microfracture, large talar injuries (>2 cm2) or cases with deep bone cysts, autologous osteochondral transplantation or chondrocyte transplantation, etc., can be attempted with an excellent rate of about 90%. The main symptom of osteochondral injury of the talus is weight-bearing pain in the ankle joint and aggravation after exercise. MRI examination can improve the correct diagnosis of osteochondral injury of the talus and provide a more accurate basis for surgical treatment. The status of osteochondral repair can be clarified by MRI review or secondary arthroscopy. Long-term postoperative follow-up can be used to further understand whether the outcome has changed over time.