Abstract
Sir,
I am very grateful to the author of the letter for the details of my article, for which there are some points that need attention to help further clarify the focus of delayed reduction of femoral neck fractures in children.
1. For femoral neck fracture reduction, the aim is to achieve anatomical reduction not the acceptable reduction. In our experience, both closed reduction and open reduction require anatomical reduction. We tried to close reduce fractures, if possible. If tried for three times and failed to achieve anatomical reduction, we change to open reduction to achieve anatomical reduction under direct vision. Internal fixation is required after reduction, and hip spica cast is required after internal fixation.
Indeed, “conservative management” in “Patients and methods–treatments” seems confusing readers, we are sorry we did not make it clear. It is easier to express clear to delete “conservative management”. The best meaning is “The treatment modalities used were closed reduction and internal fixation (CRIF), or open reduction and internal fixation (ORIF), depending upon the patient profile and fracture pattern”.
Literature suggests 1 that “A hip spica cast must be used to supplement internal fixation in all patients who are younger than 10 years. For older patients, if the stability of the fracture is questionable or if the child’s compliance is doubtful, the surgeon should not hesitate to apply a hip spica cast. The quality of reduction and the stability of the fixation have a direct impact on the occurrence of nonunion.”
We suggest hip spica cast for both younger patients and older patients (the maximum age in this study is 14 years).
Patients go home a few days after operation. Without hip spica cast, the children will stand, walk and even run, not really achieve weight-free recovery. We also encountered several cases in which the children removed cast by themselves and walked, resulting in cartilage dissolution, femoral head necrosis and other serious complications. Therefore, we used hip spica cast for about 2 months after operation. When the radiography showed the fracture line began to heal, the cast was removed, and the patient began to bedside exercise, non–weight-bearing walking and weight-bearing walking step by step.
2. In our study, in these cases, only one patient with Delbet type I (1-year-old; case 12) was treated with open reduction and two 1.6-mm Kirschner wires for internal fixation.The other fractures (type I, II, and III; cases 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, and 16) were stabilized with two 4.5- to 6.5-mm cannulated screws, depending on the size of the children’s femoral neck.
3. For the classification of femoral neck fractures in children, Delbet classification is commonly used. Delbet classification is mainly used to determine the location of the femoral neck fracture. However, for the displacement degree of femoral neck fractures, Garden classification is generally accepted. Garden classification can determine whether the fracture is complete, displaced, or angled, 2 meanwhile Delbet classification cannot solve these problems.
For the initial version of this article, we did not use Garden classification. A reviewer suggested adopting Garden classification. Considering that it could indeed explain the characteristics of fracture displacement and angle, we followed the reviewer’s advice and added Garden classification, trying to study children’s femoral neck fractures from the perspective of Garden classification.
In “Assesment,” “Table 2” explains Garden classification, not AVN classification. The article makes the readers misunderstand. Indeed, AVN imaging types were Delbet classification, three types were “type I, whole head: necrosis of both femoral head and neck; type II, partial head: necrosis of femoral head, not neck; type III, femoral neck: an area of necrosis of the femoral neck from the fracture line to the physis, not head.” 1
4. In three patients with short femoral neck in this series, the amount of shortening compared to the contralateral normal side were 1.04 cm (case 6, right 6.15 cm vs. left 5.11 cm), 0.60 cm (case 10, right 3.73 cm vs. 4.43 cm), 0.26 cm (cases 12, right 1.94 cm vs. 2.20 cm). Femoral neck length was measured from the femoral head center along the femoral neck axis to the cross point of the shaft axis and femoral neck axis. 3 The lower limb length discrepancy in these patients were less than 2.0 cm, so there was no significant difference in gait. 4
5. Hip varus, valgus, nonunion, chondrolysis, avascular necrosis, unequal length of lower limbs, short neck deformity are the complications. However, no cases of coxa varus, premature physeal closure, nonunion, or chondrolysis were found in the follow-up of children treated according to the standards of our department. Probably anatomical reduction, rigid internal fixation, and plaster hip cast help decreasing these complications, however few cases and short follow-up time in this study may lead to deviation.
The children with AVN have Ratliff Score as “good” or “fair,” so they do not need additional operation for this complication.