ABSTRACT
Objective: To sum up staging treatment experiences of hip preservation for avascular necrosis of the femoral head (ANFH) according to China-Japan Friendship Hospital Classification (CJFH Classification). Methods: The literature about hip preservation of ANFH was extensively reviewed, and a staging treatment method for ANFH was set up base on CJFH Classification and the 28 years of clinical experience in this research group. Results: According to CJFH Classification, the ANFH can be rated as types M, C, and L. And the type L is rated as L1, L2, and L3 subtypes. The staging treatment method for ANFH based on CJFH Classification is set up. Conservative treatment was selected for CJFH-M patients because the necrotic area is small and in the medial non-weight-bearing area. Minimally invasive sequestrum clearance, impacting bone graft, and supporting allogenic fibular graft is selected for CJFH-C patients because the necrotic area is also small and in the lateral non-weight-bearing area. If patients are in CJFH-L1, normal bone area is less than 1/3 on hip abduction radiograph, the sequestrum clearance and impacting bone graft via surgical hip dislocation approach can be selected. If patients are in CJFH-L1, normal bone area is more than 1/3 on hip abduction radiograph, the transtrochanteric curved varus osteotomy can be selected. The rotational osteotomy on the base of femoral neck via surgical hip dislocation approach is for CJFH-L2 patients. Total hip arthroplasty via direct anterior approach is for CJFH-L3 patients. Conclusion: The staging treatment method for ANFH according to CJFH Classification has good short-term effectiveness. But the long-term effectiveness needs further follow-up.
ABSTRACT
BACKGROUND: It is reported that the hip-conserving effect of osteonecrosis of femoral head is closely related to the retention of lateral column. The classification of China-Japan Friendship Hospital is based on the three-column structure, and the prediction accuracy of femoral head collapse is high. OBJECTIVE: To establish a three-dimensional finite element model for China-Japan Friendship Hospital classification of femoral head necrosis, and to analyze the mechanical changes of fibula implantation in each classification by finite element method, and to explore the significance of lateral column retention in hip preservation, so as to provide a basis for precise prediction of collapse of the classification. METHODS: Three groups of 11 kinds of three-dimensional finite element models of normal femoral head, China-Japan Friendship Hospital type femoral head necrosis (type M, type C, type L1, type L2, type L3) and fibula implantation were established. The finite element analysis was carried out by ANSYS software. The maximum stress, maximum displacement and load transfer mode of proximal femur were observed in each group. RESULTS AND CONCLUSION: (1) In the necrosis group, the strain was the largest, and the displacement was different due to the different types of necrosis. The displacement changes were as follows: Type M < type C < type L1 = type L2 < type L3. The displacement recovery of fibula implantation group was lower than that of the normal group, and the displacement recovery was different due to the different necrosis types. The displacement changes were as follows: Type M < type C < type L1 < type L2 < type L3. The reduction range of the displacement of the repaired necrotic femoral head gradually decreased from the lateral column to the medial column, which was lower than the maximum displacement of the normal femoral head. (2) The peak value of the stress nephogram of the loading area of the femoral head after necrosis was higher than that of the normal group. The peak value of necrotic type M was nearly normal. The peak value of necrotic type C was 74.5% higher than that of the normal group, and the peak value of necrotic type L was more than 100% higher than that of the normal group. The peak value of necrotic type M after operation was not only 14.2% lower than that before operation, but also was lower than that of the normal group. The peak value of necrotic type C after operation was 5.3% lower than that before operation, but higher than that of normal group. The peak value of necrosis type L after operation was lower than that before operation, but significantly higher than the normal level. (3) The load transfer in the normal femoral head was continuous. The conduction path was from the lateral column of the femoral head to the femoral moment. In the necrosis group, the internal load transfer of types M and C femoral head was continuous, and the conduction of type M was basically consistent with normal. The stress of type C conduction to femoral moment was reduced. The load transfer of L1, L2 and L3 type femoral head was interrupted. The stress changed in cliff type, and was unable to transmit to femoral moment, resulting in stress concentration in load area of the femoral head. A certain effective load transfer mode was reconstructed in the femoral head of the fibula implantation group, and the stress concentration at the femoral moment occurred in all types of conduction. Part of the load was transferred to the femoral moment through fibula, and the normal load transfer mode was partially restored. (4) China-Japan Friendship Hospital type fibula placement can prevent the collapse of the femoral head to a certain extent. The location and size of the necrosis area are very important. The closer the necrosis is to the lateral column, the easier it is to collapse and the more difficult it is to repair. The retention of the lateral column is an important factor for accurate prediction of the collapse of the femoral head.