Intramedullary nails have become the mainstream treatment for intertrochanteric fractures due to their advantages of being minimally invasive and biomechanics features. However, with the widespread use of intramedullary nails, distal locking procedure as a routine operation gradually raised controversy. Complications emerged associated with distal locking, including fascia lata irritation, secondary femoral fractures [5, 7, 8], thigh pain and erosion of the femoral cortex, femoral cortical hypertrophy and superficial femoral artery . Due to this emerging problem, some researchers investigated the utility of using distal interlocking screws in their biomechanical studies, demonstrating that distal locking is unnecessary in stable and in some unstable intertrochanteric fractures [6, 21–26]. Many studies compared the outcomes of distal locking and unlocking in the intramedullary nailing for the treatment of intertrochanteric fractures, but clear inconsistency in the treatment effects were described in these studies. Thus, the optimal method to deal with distal locking during nailing of intertrochanteric fractures remains controversial [12–20]. Therefore, the purpose of this meta-analysis and systematic review was to summarize the existing evidence to determine the safety and efficacy of distal locking and unlocking in the nailing of intertrochanteric fractures. At present, no similar meta-analysis has been performed.
This study considered 9 articles that included a total of 1978 patients with a similar baseline. The results showed that the distal unlocking group had shorter operation time, less intraoperative bleeding, transfusion rate, and thigh pain in the treatment of femoral intertrochanteric fracture compared with the distal locking group. No significant differences in safety- related outcomes including mortality, infection rate, cutting out, loss of reduction, backing out of lag screws, cephalic screw breakage, nail breakage, and peri-implant fractures was found. Efficacy-related outcomes including nonunion, delayed healing rates, and Harris functional score were also not significantly different. According to the GRADE tool, most of these outcomes were graded as low-moderate.
Consistent with the foregoing expected results, the operative time, blood loss, rate for blood transfusion, and radiation exposure in ULN were significantly reduced compared with LIN. The operative time was shorter and the radiation exposure was lesser because of less surgical procedures. The reason for the low amount of blood loss was mainly due to the smaller trauma and shorter operation time. The short operation time and the small amount of intraoperative blood loss minimize the anaesthetic effect on respiration and blood circulation, and represent an advantage for the recovery of elderly patients after surgery. Reduced transfusion implies a reduced risk of disease transmission, transfusion reactions and immunomodulation, and it also reduces the costs since transfusions are rising in price . Less radiation exposure can reduce the danger and increase the protection for both patients and surgeons. A statistically significant difference of heterogeneity existed due to different hospitals that calculate the operating time and blood loss, different internal fixation, and the inconsistency of the surgeon proficiency.
The overall results regarding thigh pain were significant, suggesting that the use of distal screw might be harmful. This is consistent with the literature reports [12, 15, 16, 18]. However, when subgroup analysis was performed, the difference was not significant, suggesting that the reliability of this result was not strong.
Rates of peri-implant fracture were similar in both LIN and ULN group and thus, not statistically significant. However, the data were heterogeneous (P = 0.010; I²=67%), mainly due to Skala-Rosenbaum J et al. study . After the removal of this article, although the conclusion remains unchanged, the heterogeneity significantly decreases (P = 0.82; I²=0%). In the present study, after analysing a group of 849 pertrochanteric fractures managed with short nails, it was surprising to find that patients without distal locking had an 85.7% greater risk of peri-implant fracture. This result is different from the results of all the clinical and biomechanical studies considered in our work. Methodologically speaking, the reason of this difference is due to the absence of random and blind methods in the research of Skala-Rosenbaum J et al. and in addition, the baseline and weight-bearing time between the two groups were not introduced. Clinically speaking, the difference might be theoretically related to the fracture type or to the inappropriate selection of patients for unlocked nailing, whose fracture should be a stable fracture for this choice of using unlocked nailing, because the dorsomedial fragment or the existence of recessive fracture is of difficult detection by ordinary X-ray [18, 28]. In addition, peri-implant fractures are associated with instability. The stability is not only related to internal fixation, but also to surgical reduction. Poor surgical reduction can also lead to instability . Skala-Rosenbaum J et al.’s study did not mention the effect of post-operative reduction. Furthermore, their study did not give a detailed description of the tip apex distance and the position of the head nail, which are closely related to the stability.
This meta-analysis has some limitations. 1. These nine articles included 1978 cases of intertrochanteric fractures of the femur. Five of them are observational studies. Some defects are present in the research design, and the performance of the statistical tests may be insufficient. 2. The nine articles involved do not describe each measurement and outcome in detail, and the validity of the statistical tests may be insufficient. We tried to contact the authors if the included studies for more information, but we did not receive any response regarding the possibility to check the data of their research. Therefore, subgroup analysis of some aspects including fracture types, intramedullary nails, and complications was not performed to rule out possible confounding factors, thus affecting the effectiveness of our research. 3. The inconsistence about nails length, number or type of cephalic screws and angle between cephalic screws are unclear aspects that make our results questionable.
Further research should be performed considering larger, multicentre, randomized controlled study taking into account the need for large clinical trials with a valid, type-specific fracture and uniform method for the measurement and definition of the outcome. Our recommendation is that CT should be performed to identify the type of fracture as stable before deciding to use distal locking nails. Patients with wide diameters of medullary cavity, comminution of the lateral wall of the greater trochanter, and large posteromedial fragment extending distally below the lesser trochanter should be not taken into consideration for unlocked intramedullary nailing. Current studies mainly focus on short nails, but relatively few on long nails. Therefore, this study of long intramedullary nailing for intertrochanteric treatment should be enriched with other studies properly performed as we recommended above.