Overview, management of occult femoral neck fracture in high-energy femoral shaft fracture
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A 26-year-old man who was in a motorcycle crash arrived at the ED with a Glasgow Coma Scale score of 3T. Following stabilization in the trauma bay, trauma scans were obtained.
The patient sustained extensive non-orthopedic injuries including severe craniofacial trauma (multifocal subarachnoid and subdural hematomas), bilateral rib fractures with associated pneumothorax and sternal fractures. He also sustained significant orthopedic injuries, including a right diaphyseal femur fracture, right diaphyseal tibia fracture, right patella fracture, type 1 open diaphyseal radius and ulna fractures, left inferior pubic ramus fracture and right scapular body fracture. There was no evidence of ipsilateral femoral neck fracture in preoperative radiographs or the CT scan (Figure 1). There was also concern for superficial femoral artery injury and impending compartment syndrome of the patient’s right thigh. Therefore, he was taken emergently to the OR for vascular exploration and thigh fasciotomies by the general surgery trauma team. Orthopedics was consulted intraoperatively for temporization of the patient’s long bone injuries, which included using a spanning external fixator for the entire right lower extremity and irrigation and debridement with sugar-tong splinting of his right upper extremity.
Source: Eben A. Carroll, MD
Utilizing principles of early appropriate care, he was taken back to the OR for definitive fixation of his right femur, right tibia, and right forearm 48 hours after initial presentation. Based on the injury patterns, it was determined that retrograde intramedullary (IM) nailing of the femur and IM nailing of the tibia were appropriate. Postoperatively, the patient was made weight-bearing as tolerated in a knee immobilizer due to his patella fracture.
On postoperative day 7, the general surgery trauma team obtained a CT abdomen that showed a displaced right femoral neck fracture (Figure 2).
What is the next best step to manage this patient?
See answer below.
Open reduction and internal fixation of femoral neck fracture
At this time, the patient’s prognosis was improving, and he was taken urgently (within 24 hours) for operative fixation of his femoral neck fracture.
Operative details
A modified Smith-Petersen approach was used in this case. The incision was made just distal and lateral to the anterior superior iliac spine and coursed for approximately 10 cm toward the lateral border of the patella. The superficial interval was developed between the tensor fascia (superior gluteal nerve) musculature and the sartorius (femoral nerve). A deeper dissection was done between the gluteus medius (superior gluteal) and the direct head of the rectus femoris (femoral nerve).
The hip capsule was readily visualized. The capsulotomy was performed with the transverse limb of the capsulotomy toward the acetabulum to protect the femoral head blood supply. The fracture was readily identified. There was no significant comminution. First attempts at reduction resulted in a slight varus deformity. A compression and distraction forceps with one compression wire in the superior femoral neck and the other in the greater trochanter were used to apply a valgus force and anatomically reduce the fracture via direct visualization.
Following reduction, the fracture was secured with a two-hole Synthes Femoral Neck system (FNS). Biplanar fluoroscopy confirmed proper reduction of the fracture and appropriate placement of all hardware (Figure 3). The capsule was closed and the remaining closure proceeded in a layered fashion. Postoperatively, the patient was made non-weight-bearing to the right lower extremity with follow-up imaging done at 6 weeks and 5 months postoperatively (Figure 4).
Discussion
The incidence of concomitant ipsilateral femoral neck fractures in the setting of high-energy femoral shaft fractures has been reported to be as high as 9%, with the reported rate of missed diagnosis of occult femoral neck fractures being as high as 30%. Despite the awareness of this injury pattern, there has been no standardized protocol for preoperative diagnosis. Paul Tornetta III, MD, and colleagues developed a protocol at their institution that included a fine-cut CT of the ipsilateral femoral neck (2-mm cuts), intraoperative lateral of the femoral neck, and a postoperative anteroposterior (AP) and lateral. This protocol resulted in a 91% reduction in missed neck fractures. In our patient, CT with 1.3-mm cuts and immediate postoperative AP and lateral showed no evidence of femoral neck fracture. Nathan B. Rogers, MD, and colleagues looked at the 1-year results of using rapid-sequence MRI to identify femoral neck fractures. In this study, the MRI protocol identified an additional ten femoral neck fractures not identified on standard radiographs and thin-cut CT scans (2 mm). For this study, it increased the incidence of neck fractures from 7.7% (9/116) to 16.4% (19/116). It is important to note that this occurred at a large tertiary care center where rapid-sequence MRI is readily available. Because of this unacceptably high rate of occult femoral neck fractures, anterograde femoral nailing with prophylactic neck fixation has become standard practice at the researchers’ tertiary care center for the treatment of isolated high-energy femoral shaft fractures.
In the event of a femoral neck fracture identified preoperatively, order of fixation occurs from proximal to distal with anatomic reduction of the femoral neck taking precedence. If the fracture is displaced, an open reduction with direct visualization of the fracture site is performed. In this case, an anterior modified Smith-Petersen approach was used. Studies have shown that the major risk factor for development of avascular necrosis of the femoral head following femoral neck fracture is quality of reduction. A recently published study looked at differences in reduction quality based on the approach used and showed no difference between a laterally based approach (Watson-Jones) and an anteriorly based approach (modified Smith-Petersen). Approach should be based on surgeon preference and comfort level.
There has been a trend toward using the Synthes FNS at this institution for fixation of femoral neck fractures. It is a fixed-angle construct with an anti-rotation screw and a sliding, cylindrical bolt that allows for compression at the fracture site as the patient begins to ambulate. Thus, it acts in a way similar to a sliding hip screw with a separate anti-rotation screw but within the same construct. Moreover, a biomechanical cadaveric study by Karl Stoffel and colleagues showed the FNS is at least equivalent to sliding hip screw and superior to three cannulated screws.
Conclusions
Although relatively rare, ipsilateral femoral neck fractures in the setting of high-energy femoral shaft fractures are a well-described injury pattern. The treating surgeon must have a high index of suspicion for occult femoral neck fractures to minimize the risk of a missed diagnosis. Unfortunately, there has been no consensus on how to diagnose these injuries. However, having a standardized protocol and potentially evolving modalities (rapid sequence MRI) can help reduce the chances of a missed injury. Also, no single implant or implant combination has been shown to be superior to another. Until better evidence is found, treating surgeons must use techniques and implants they feel provide patients with the best possible outcomes.
- References:
- Jones CB, et al. J Am Acad Orthop Surg. 2018;doi:10.5435/JAAOS-D-17-00497.
- Min BW, et al. Orthopedics. 2011;doi:10.3928/01477447-20110317-13.
- Patterson JT, et al. J Orthop Trauma. 2021;doi:10.1097/BOT.0000000000002068.
- Rogers, NB, et al. Injury. 2021;doi:10.1016/j.injury.2021.05.009.
- Stoffel K, et al. J Orthop Trauma. 2017;doi:10.1097/BOT.0000000000000739.
- Tornetta P III, et al. J Bone Joint Surg Am. 2007;doi:10.2106/JBJS.F.00297.
- For more information:
- Eben A. Carroll, MD; Rosser W. McCallie, MD, an orthopedic resident PGY-4; Donald J. Scholten II, MD, PhD; and Kelly M. Stumpff, MD, an orthopedic trauma surgeon, can be reached at Wake Forest Baptist Health, Department of Orthopaedics, 1 Medical Center Blvd., Winston-Salem, NC 27157. Carroll’s email: ecarroll@wakehealth.edu. McCallie’s email: rmcclli@wakehealth.edu. Scholten’s email: dscholte@wakehealth.edu. Stumpff’s email: stumpffk@gmail.com.
- Edited by Steven D. Jones Jr., MD, and Donald (DJ) Scholten, MD, PhD. Jones is a chief resident in the department of orthopedic surgery at the University of Colorado. He will pursue a fellowship in sports medicine at Stanford University following residency completion. Scholten is a chief resident in the department of orthopedic surgery at Wake Forest University School of Medicine in Winston-Salem, North Carolina. He will be a sports medicine fellow at the University of Michigan following residency. For information on submitting Orthopedics Today Grand Rounds cases, please email: orthopedics@healio.com.
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