Basicervical proximal femoral fracture is a special type of fracture located in the intermediate border of intracapsular and extracapsular fracture. As a result, they have varying definitions in the literature[10, 11, 17]. Due to its greater biomechanical instability and higher surgery failure rates, it’s of significant importance to get proper diagnosis. Watson defined the basicervical fractures more strictly based on X-Ray as occurring at the base of the femoral neck and exiting above the lesser trochanter but was more lateral than a classic transcervical fracture. To our knowledge, there’s no prior study to use CT to further precise basicervical fracture. In our study, 5 of all suspect basicervical fracture was excluded and turned out to be intertrochanter fracture by CT scan (Fig. 1). In diagnosis, X-ray alone is not accurate enough for the diagnose of basicervical fracture. As a periarticular fracture, CT scan is highly recommended to confirm the integrity of the greater and lesser trochanters with the shaft. As a result, the prevalence of basicervical proximal fracture treated with internal fixation in our organization was 3.0% (25/821).
The primary factors that predispose a patient with internal fixation to poor prognosis include highly unstable fracture, inadequate reductions, improper fixation chosen and poor rehabilitation strategy[17, 18]. In addition, low bone density is an independent risk factor when treating with internal fixation. Watson reported the failure rate of CMN was 54.5% (6/11) and suggested that CMN may be inadequate for fixation of 2-part basicervical fractures. Different CMNs they used in the study produced less effective compression between fractures which may be one reason of high failure rate. Additionally, low bone density might be an ignored factor as the patients included were older than most studied (the average age in the failure group was 75 years old). Anti-osteoporosis treatment was also recommended to the patients after surgery in our study.
Basicervical hip fractures are reported with high failure rates after the treatment with osteosynthesis[1, 11]. As femoral neck fracture, basicervical fracture is closer to intertrochanter with large pauwel’s angle that demonstrates high shear force when bearing weight. It has even greater biomechanical instability than intertrochanteric fractures. Kuokkanen reported that the use of multiple screws was not recommended in the treatment of basicervical fracture. When treated as an extracapsular fracture, both biomechanical and clinical studies have revealed better stability and clinical outcome[14, 13, 10, 12]. It can be treated with DHS or CMN. In a biomechanical study of different internal fixation techniques, Blair noticed that the lateral position of the basicervical fracture line minimized the support of fixation provided from the lateral cortex. As a result, basicervical fracture has more collapse and failure than intertrochanteric fracture.
Certainly, there is considerable debate regarding the optimal surgical fixation of basicervical fractures[11, 14, 8]. Biomedical studies have shown CMNs could provide an increased load to failure and great anti-rotation properties. The fault tolerance of CMNs insertion is relatively high with minimal invasive to the soft tissue and relative stability of reduction that are bonded to decrease operational duration, surgical trauma, and the inability of the implant to survive until fracture union. However, in our study, the patient treated with Intertan sustained reoperation due to excessive varus collapse and finally cut-out of lag screw although an acceptable reduction quality (5–10 valgus) was achieved during the surgery. As fracture reduction is a significant component in the prognosis of uneventful fracture healing, efforts should be devoted to improvements in reduction. Reduction in valgus and positive buttress alignment would have a positive effect on postoperative fracture stability. Positive buttress is hard to get in basicervical proximal femoral fracture due to dilemmatic area of the fracture. Anatomic reduction may be the key to resist the shear force. Therefore, the reduction criteria for hip fractures described by Fogagnolo is not fit for basicervical fractures which allows 20 degree of angulation in lateral view . The criteria of reduction of basicervical fracture should be even stricter than that provided by Baumgaertner. The insertion process of internal fixation may cause further displacement of the fracture, so the maintenance of the fracture alignment and timely fluoroscopy during the operation are necessary.
Our study showed there was no significant difference in function recovery and complication rate between two group. The result also consists with the study by Kim et al who compared the effects of DHS and CMN on the treatment of basicervical fractures. They proved that CMN with blade type or two integrated screw type could drastically reduce the failure rates in the osteosynthesis of basicervical hip fractures. PFNA was designed to improve angular and rotational stability with the blade type lag screw while InterTAN nail provides rotational stability and immediate intraoperative linear compression with two integrated interlocking lag and compression screws. Inserting the PFNA blade can also compact the cancellous bone and provide additional stability. As for unstable proximal femeral frature, PFNA and InterTAN nail are effective CMN options[23, 24]. TAD value of CMN is considered a key indicator to predict postoperative cut-out complications. Patients with a TAD < 25 mm were less likely to encounter screw cut-outs complication. In our study and average TAD was 20.3 mm and associated with fewer failures than previous studies.
The DHS has long been considered the “gold standard” for operative fixation of peritrochanteric fractures until the advances in CMN were reported[14, 22, 25]. However, current study showed DHS was still effective and possessed unique advantages treating basicervical hip fractures. Better reduction could be obtained as the distal fragment was retracted laterally using a bone hook or a Hohmann retractor after traction of the fractured bone. Then one or two k-wire was inserted to contral rotation of the proximal fragment and maintain the reduction fixation during the fixtion. The K-wire could also be used as guide pin of the derotation screw. The additional derotation screw could improve strength and rotational control of DHS in a biomedical study although ambivalent results have been reported by Imren. As basicervical fractures in the elder population treated with osteosynthesis resulted to high rates of surgical complications, revision surgery is also an importance factor when choosing initial treatment. In cases of failure, conversion hip arthroplasty can be a favorite treatment option. Bercik et-al compared outcomes of conversion total hip arthroplastys for femoral neck fractures initially fixed with DHS versus cephalomedullary nails and reported CMNs were difficult to remove and their removal can result in complications during conversion arthroplasty. Thus, it would prolong operative time and increase blood loss for patients and even cause persistent hip pain after conventional surgery in the CMN group[27, 28].
The goal of fracture treatment is always early functional rehabilitation. However, due to shear stress at the basicervical site, load commitment may affect the healing of the fracture and increase postoperative complications. We prolonged the time to weight-bear after surgery but encourage active leg exercises on-bed. That maybe another reason of less complication rate of our study.
There are several unavoidable limitations in our study. First, our study was designed retrospectively with the small number of patients. More date with multiple trauma centers may make our conclusion more convincing. Second, various factors were proposed but could not be further analyzed in this study. Reduction quality and BMD are two important factors influencing the prognosis, but we couldn’t get a conclusion whether they play a role in the complications due to limited data and small sample size. However, we will design more rigorous prospective clinical studies to analysis factors of one certain device to further investigate the root cause of difficulty of treating basicervical fractures.