Double reverse traction repositor versus traction table for the treatment of intertrochanteric femur fracture: A comparative Study

Background The aim of this study was to compare the clinical results between double reverse traction repositor and traction table used for the treatment of unstable intertrochanteric femur fracture. Methods This retrospective study included 95 patients with AO/OTA 31- A2 and A3 proximal femur fracture, who underwent double reverse traction repositor or traction table facilitated Asian proximal femoral nail antirotation (PFNA-II) nailing. The demographics, duration of operation, blood loss, part loading time after surgery, the period of union of fracture, complication were assessed. Clinical and radiological outcomes were evaluated. Results There were no significant differences in respect to demographics and fracture characteristics. Duration of patient positioning and total operative time were significant longer in traction table group than that in double reverse traction repositor group(p<0.001). No differences were found intraoperative blood loss, part loading time after surgery, fracture healing time and Harris Hip Score between two groups. Conclusion When treating unstable intertrochanteric fractures, double reverse traction repositor is superior to tract table in respect to operative time and duration of patient position, despite an additional ipsilateral anterior superior iliac spine (ASIS)incision and drilling of ASIS and femur condyle.


Introduction
The unstable intertrochanteric fracture usually involves the trochanter minor and posteromedical cortex, even extends into subtrochanteric region [1]. It is popular to manage unstable intertrochanteric fracture with closed reduction and cephalomedullary nailing [2]. The determinant factor that influences the prognosis is the quality of reduction, which is almost achieved through the application of a traction table(TT).
However, some complications related with traction table usage have been reported,   including extra time needed to set up traction table, neurological injuries, soft tissue contusions, compartment syndrome, crush syndrome and vascular injuries [3]. These complications may cause terrible consequences to patient, which compromises the use of traction table. In order to avoid these potential complications, the double reverse traction repositor was employed as an alternative to traction table for the closed reduction of the fragments and PFNA-Ⅱ fixation.
Double reverse traction repositor (DRTR) is designed by Zhang el al to achieve the closed reduction of a displaced fracture based on a concept of skeletal distraction [4]. Zhang

Surgical Technique
All operation were performed by the same experienced orthopedic surgeon. If the double reverse traction repositor (DRTR) was used, the surgical process was described as follow.
The patients were placed in a supine position under general anesthesia on the radiolucent performed. The repositor consists of a reduction scaffold, traction bow, traction pin, radiolucent connecting rod, distal reduction pin and proximal anchor (Fig. 1). Firstly, a 2cm incision and drill of the ipsilateral anterior superior iliac spine(ASIS) was applied to screw a 3-mm Schantz pin. The Schantz pin was linked to the proximal end of the radiolucent connecting rod via a cardan shaft. The optimal length of connecting rod was applied according to distance between ASIS and femoral condyle. Then, the distal end of rod was fixed to the traction scaffold with four legs that can be adjustable to fit the height. Another 2.5-mm K-wire was screwed at the femoral supracondylar level and

Postoperative rehabilitation
The isometric quadriceps and a ankle pump exercise were performed on the first day after surgery. The active flexion and extension of hip and knee were encourage and X-ray were reviewed on post-operative day two. The low molecular weight heparin was used for anticoagulation on the first day after surgery. Full weight-bearing was permitted when the disappearance of the fracture line on X-rays and pain on hip.

Clinical Data
The remaining placement of blades were considered as suboptimal fixation [5]. For evaluation of reduction quality, the cortical continuity was confirmed anatomic, 5-10 0 varus/valgus was confirmed good, and more than 10 0 varus/valgus was defined poor. [6] 2.6 Statistical analysis  For radiological assessment of the quality of the reduction and fixation, the radiographs were taken on post-operative day two. As shown in Table 3, fractures reduction were accepted anatomic in 58 patients, good in 30 patients on the postoperative radiographs evaluation. In addition, the placement of blades were optimal in 80 patients. There were no significant differences between two groups in fracture reduction and implant position (P > 0.05).  We found total operative time was shorter for DRTR group compared with TT group. This can likely duo to the decreased time required to patients positioning and easy abduction and adduction of the hip joint at will when inserting the guide wire and PFNA-Ⅱ in DRTR group. In traction table group, the mean duration of patient positioning and fracture reduction was comparable with the published report [7]. However, mean duration of patient positioning in DRTR group was only 6.5 ± 1.2 minutes. This may be attributed to easy double reverse traction repositor assembly. Of note, the decreased operative time was a critical determinant of mortality in surgical treatment of hip fracture, especially for elderly who was extremely sick.
Recently, management unstable intertrochanteric fractures with PFNA-Ⅱ has been a promising approach [1]. There is growing evidences that excellent intertrochanteric fractures reduction should be performed before intramedullary nailing, otherwise the failure of nail fixation may be inevitable [8]. In this study, we discovered that satisfied clinical efficacy was obtained when unstable intertrochanteric fractures were treated with double reverse traction facilitating PFNA-Ⅱ. The results showed more than 80% patients obtained excellent-good Harris Hip Scores at the end of follow-up.
The quality of reduction takes the primary responsibility for the ideal position of PFNA-Ⅱ and superior clinical outcomes. In DRTR group, postoperative X-ray evaluation showed a good-anatomic reduction in 95% of cases and central-central and inferior-central placement of blade in femoral neck was achieved in 47 cases (84%). This methods has obvious advantages over tradition traction table. As traction table usually placed between the perineum and distal extremity, it only produces skin traction force that steps over hip, keen and ankle joints before transmitting to the fracture site by soft tissue. This kind of skin traction may fail to provide sufficient force to correct the angular and rotational displacement [9]. The double reverse traction repositor is fixed to the ASIS and distal femur via traction bow, thereby, a skeletal traction system is formed. Once the distal tract handle was reverse rotated, two opposing directional forces was generated to distract and reduce the displaced intertrochanteric fractures. Therefore, the same reduction outcome can be achieved with less tractive force in patient treated with DRTR compared with traction table, which significantly decreased the occurrence of soft tissue injuries.
Moreover, the resistant force by the ASIS via connection rod pulling can counter the distal femoral traction force. Therefore, there is no need to place perineal post required in traction table, which avoids the complication resulted from the compress of labia or scrotum [10]. In our study, no patients in DRTR group suffered from peroneal nerve palsy, perineal ulcers or nerve injury.
When dealing with intertrochaneric fracture reduction, techniques have been employed to correct the varus angulation, external rotation and posterior sag of proximal fragment.
Traditionally, the table traction has become a standard procedure for intertrochaneric fracture reduction via longitudinal traction and internal rotation of distal fragment.
However, in certain intertrochaneric fracture, the external rotation of proximal fragment because of forces by the short external rotators of hip can may compromise the reduction [11]. Some authors reported that fracture with more than 2 independent fragments, especially type A2 fracture with a posteromedial fragment, if applying internal rotation to the distal injury limb, can lead to malunion and deformity that need a revision surgery [12]. To avoid that, the surgeon can externally rotate lower injured limb to achieve the ideal reduction, which makes the whole extremity in the external rotation but  [13].Therefore, moderate adduction of hip is required for surgeon to easily locate the top of great trochanter and insert the PFNA-Ⅱ, especially dealing with fat patients. In the present study, the double traction technology represents a prone method to provide distinct internal rotation of hip for anatomic reduction as well as adduction for optimal insertion of PFNA-Ⅱ.
It must be noted that one elderly patient from DTRD group had an iatrogenic ASIS fracture. When the DTRD applied in the elderly, the bone mineral density should be perform to rule out the severe osteoporosis, which may increase to ASIS fracture during the skeleton traction. Based on our experience, the technique to prevent ASIS fracture in DTRD group is that the position of drill is recommended more than 3 cm underneath the top surface of ASIS and size of Schantz pin used should be no more than 3-mm.
Although an extra incision of ASIS and drilling in ASIS and femoral condyle were required in DTRD group, no significant differences in mean blood loss and surgical time were found between two groups. The 2-cm incision without further tissue and muscle dissection may cause small amount of blood loss and did not reach the significantly statistical difference.
Moreover, the cost of the double reverse device is less than 40.000 Yuan (5000 USD), which is highly cheaper than the traction

Funding
This article was funded by the Novel medical techniques of the second xiangya hospital of Central south university.

Ethics approval and consent to participate
The study protocol was reviewed and approved by the Committee On Ethics board of the second Xiangya hospital of Central South University. Because the study was retrospective, the inform consent was not necessary.