Proximal femoral fractures are common among older people requiring surgery for stable fixation and early ambulation. From the inception of DHS, such fixtures have become the gold standard for the treatment of intertrochanteric fractures [
5‐
7]. In patients with stable fractures such devices produce excellent results. However, in patients with unstable fractures, the dynamic hip screw and plate are associated with an increased prevalence of complications such as cut-out, shaft medialization, shortening, and subsequent loss of reduction. For these reasons, there has been a sustained interest in the use of an intramedullary nail to treat proximal femoral fractures. However, the intramedullary method for trochanteric fractures requires extensive surgical experience. The incidence of complications, for example cut-out, femoral shaft fractures, and the steep learning curve has resulted, in the past, in the loss of popularity for these devices.
With the axial biomechanical advantages of the intramedullary nail, a series of intramedullary fixation implants evolved from the Gamma nail, PFN and PFNA to the latest TRIGEN INTERTAN nail. With the unique integrated, interlocking screw constructs, the TRIGEN INTERTAN nail provides all the benefits of a traditional surgical approach for the antegrade intramedullary nail, and also increases the stability and the resistance during the intraoperative and postoperative femoral head rotation. Furthermore, the INTERTAN™ compression screw is always against the nail so a medial migration is impossible; thus, eliminating the Z-effect. For the above reasons, the TRIGEN INTERTAN is technically an ambitious operative procedure for the treatment of intertrochanteric fractures. However, information about the intraoperative technical complications of implantation had hardly ever been reported.
When the first version of the Gamma nail was introduced to Asian patients, Leung
et al.[
8,
9] did report problems about the geometric mismatch of the Gamma nail and the Chinese femur. Subsequently, a series of modifications in the design had improved it. Windolf
et al.[
10] also had reported that sufficiently deep insertion of the selected nail was impossible in three patients because of the anticurvation of the femoral shaft. In two of these cases, the entry point of the nail was placed too far dorsally. These problems were solved by changing to a thinner nail. As for Hwang
et al.[
11], they had reported the mismatch between the implant and the bowing of the femur in the coronal plane. During the insertion of the nail, an iatrogenic fracture developed along the medial cortex of the subtrochanteric area. As shown in Figure
1, our patient not only had the femoral anatomical specificity of anticurvation but also lateral curvation. After analyzing the radiographs during the operation, we changed the portal entry accordingly without changing to a smaller nail and then we placed the nail smoothly. As the person ages, the femoral diaphysis enlarges and the bowing of the femoral shafts increases [
12]. The concern with using a straight intramedullary nail in a bowed osteopenic femur can result in the impinging of the main nail, and in some cases even perforating the distal femoral metaphyseal cortex. Additionally, when the nail engulfs the femoral cortex, any locking screws placed in the distal part of the femur may cause a stress riser in this area, which might lead to an iatrogenic fracture or pain in the postoperative rehabilitation period [
13]. It is difficult to perceive the bowing of the femoral shaft with AP and lateral views of the injured hip. Based on our experience, full-length AP and lateral radiographs of the injured femur are necessary for the confirmation of anatomical specificity. With this evaluation, potential intraoperative complications during implantation should come to the surgeon’s attention as well as the correspondent shift of portal entry (Figure
1). If excessive curvation of the femoral shaft in the coronal and sagittal planes is observed before the operation, then the strategy of open reduction and fixation with a DHS seems to be more rational and should be considered as an alternative method.Based on our experience with one of the cases, that is our obese patient (Figure
2A, B), we believe that it is important to achieve a vertical trajectory approach with the nail insertion; this can be difficult in obese patients. If the intramedullary nail is inserted at an oblique angle due to fat obstruction, the nail itself can impact the relatively soft bone of the lateral aspect of the greater trochanter, which could result in an iatrogenic fracture of the proximal femur. It is better to perform a vertical trajectory approach with the nail insertion; thus, a jackknife position is the preferred one in our hospital. For the case in Figure
2C, D, E when stiff resistance was encountered, we had to adjust the reamer assembly to the desired trajectory. Moreover, by utilizing the intraoperative radiographs, we had observed the anatomical specificity of the narrow proximal femoral canal that enabled us to thoroughly ream the medial cortex. With this improvement, a relatively smooth insertion was acquired. As for our patient in Figure
3A, B, the width of the proximal femoral canal was measured at around 11mm from the preoperative radiographs. We underestimated the difficulties of implants due to the measured width and the predicted osteoporosis in our 83-year-old patient. In this case, the resistance had developed for several reasons, most likely: (1) there was a less-than-ideal portal entry and (2) the trajectory resulted in the collision between the tip of the nail and the cortex in the process of moving forward. After that, iatrogenic fractures of the distal femur developed because of the violent hammering and underestimating of the bone fragility.
As described in Case 4, our patient had suffered comminute intertrochanteric fractures where there was significant shift in the fragments. To stretch the muscle that was attached to the bone, it was extremely hard to reduce the fragments and insert the nail simultaneously into the distal femoral canal - open reduction and implantation took place. After the insertion of the integrated interlocking screw, we proceeded in locking the distal slot. During the drilling, an iatrogenic fracture around the distal locking slot developed. We analyzed that the huge stress from the separated fragments on the nail resulted in the deviation of the nail and serious tension on the cortex was produced due to the impact of the distal nail. When there is serious tension, especially when the drilling point is so close to the edge, the distal cortex broke while drilling it. If serious tension had impacted on the cortex - developed due to deviation of the INTERTAN™ tip - more attention should have been paid to avoid iatrogenic fractures. Reverse rotation and gentle manipulation during drilling are recommended. Furthermore, we believe that if hard reduction is predicted from the preoperative evaluation, the strategy of open reduction and fixation with a DHS seemed to be more rational and/or should be prepared as an alternative method. In spite of the biomechanical disadvantages, a DHS has a series of advantages such as low blood loss, a shorter operation time and more satisfactory reduction in these cases [
14].