Abstract: BACKGROUND: Talus cartilage injury is a common motor system disease. This type of injury will affect the patient’s daily life and work ability, and may worsen the condition if left untreated. Surgical treatment is commonly used, but the selection of surgical methods and the evaluation of medium- and long-term follow-up results have always been difficult clinical problems.
OBJECTIVE: To explore the influence of T1ρ technique on the range of quantitative evaluation of talus osteochondral injury on the choice of surgical method and the results of medium- and long-term follow-up.
METHODS: A total of 154 patients with osteochondral injury of talus admitted to The Second Hospital of Tangshan from January 2019 to August 2022 were retrospectively selected as the study subjects. The lesion site of talus was examined by MRI before operation, and the T1ρ and T2 values of different types were compared. Different surgical methods were selected according to the different T1ρ values. Group A (n=73) was treated with microfracture surgery with T1ρ < 45 ms; group B (n=81) was treated with autogenous bone and cartilage transplantation with T1ρ ≥ 45 ms. The general clinical characteristics and curative effects of patients under different surgical methods were compared; the important factors of postoperative recurrence were analyzed by multivariate Logistic regression, and the relationship between T1ρ value and postoperative recurrence was analyzed by restricted cubic spline graph, y=1-1/(1+e-z) regression equation to build a prediction model. The stability of the model was verified by cross-checking method. 
RESULTS AND CONCLUSION: (1) Classification of talus osteochondral injury in 154 patients (type I: 36 cases; type II: 37 cases; type III: 40 cases; type IV: 41 cases), T1ρ and T2 values of the four groups were statistically significant (P < 0.05); pairwise comparison was also statistically significant (all P < 0.05). (2) After treatment of 154 patients, 7 cases (4.6%) had local swelling, 3 cases (2.0%) had pain aggravation, and 5 cases (3.3%) had wound infection. There were 2 cases (1.3%) with poor cartilage healing. (3) After treatment, there were statistically significant differences between groups A and B in terms of American Orthopaedic Foot & Ankle Society score, visual analog scale score, plantar flexor motion range, dorsoextension motion range, subchondral bone marrow edema volume, interleukin-6, interleukin-8, C-reactive protein, procalcitonin, platelet-derived growth factor, transforming growth factor-β1, and efficacy (P < 0.05). The total effective rate of group B (90%) was higher than that of group A (85%) (P < 0.05). (4) Age (OR=1.589, 95%CI: 0.305-1.252, P=0.036), interleukin-6 (OR=1.737, 95%CI: 0.974-5.254, P=0.049), interleukin-8 (OR=1.385, 95%CI: 1.066-4.355, P=0.034), C-reactive protein (OR=1.957, 95%CI: 1.323-2.178, P=0.035), transforming growth factor-β1 (OR=1.459, 95%CI: 0.897-2.455, P=0.038), T1-ρ (OR=1.687, 95%CI: 0.854-3.321, P=0.026), T2 (OR=1.843, 95%CI: 0.657-2.454, P=0.036), complications (OR=1.719, 95%CI: 0.654-3.464, P=0.019), and classification of osteochondral injury of talus (OR=3.789, 95%CI: 1.023-5.897, P=0.028) were independent risk factors for postoperative recurrence. Microfracture surgery (OR=0.751, 95%CI: 0.321-1.264, P=0.012) and autogenous bone and cartilage grafting (OR=0.649, 95%CI: 0.246-1.356, P=0.023) were independent protective factors for recurrence after medium- and long-term follow-up. (5) When T1ρ value ≤35 ms, the risk of postoperative recurrence decreased rapidly, and when T1ρ value > 35 ms, the risk of postoperative recurrence increased rapidly. (6) Further stepwise regression analysis showed that these nine risk factors were most closely associated with postoperative recurrence, and the formula for postoperative recurrence was obtained. The probability of postoperative recurrence was calculated using the regression equation. When P=0.75, the maximum value of Jorden index was 77.728, indicating that the model has a better prediction effect. (7) It is indicated that the quantitative evaluation of T1ρ before operation can effectively guide the selection of surgical methods, improve the success rate of surgery and the quality of life of patients.

Key words: quantitative T1ρ technique, talus cartilage injury, typing, microfracture, autogenous bone and cartilage grafting, follow-up