FHFD, which is caused by high-energy injury, is very complicated and difficult to treat because it requires prompt treatment, extensive approach to the muscles surrounding the hip joint, and anatomic reduction and rigid fixation due to the nature of intra-articular fractures in addition to the demand for trochanteric flip osteotomy in some patients [3, 21]. Among the 34 patients with FHFD, good outcomes were achieved for SHD with TFO in 32 patients, except 2 patients in whom AVN was caused by the association of the femoral neck fracture, demonstrating that SHD with TFO is a safe and useful approach for the treatment of FHFD.
In FHFD, three major complications are considered to warrant special attention: AVN, post-traumatic osteoarthritis, and HO [22, 23]. Post-traumatic osteoarthritis and HO can be treated conservatively or surgically, depending on the severity; however, in most cases, AVN caused by trauma requires artificial joint surgery, indicating the importance of analyzing the risk factors for AVN in patients with FHFD . Among the fractures classified according to the Pipkin system, type III fractures (i.e., femoral neck fractures with femoral head fractures) have unfavorable clinical and radiologic outcomes . Simultaneous fractures of the femoral neck and head contribute to difficulty in performing reduction and fixation, and AVN can develop owing to medial femoral circumflex artery injury that occurs with the fracture . In this study, femoral neck fractures frequently caused complications with two of the three (66.7%) patients with femoral neck fractures developing AVN.
The anterior approach has the advantage of being convenient for internal fixation because most femoral head fragments are located on the anteromedial side [27, 28]. However, Epstein et al. suggested that the anterior approach can damage the blood flow on the anterior side in addition to the blood flow on the posterior side, which had already been damaged by posterior hip joint dislocation . Moreover, the anterior approach provides limited visualization of the operative field because it does not expose the entire femoral head. It might also provide insufficient fixation because it does not offer sufficient angles for fixation screw insertion when multidirectional screw fixation is required, owing to comminuted femoral head fragments. Giannoudis et al. systematically reviewed AVN rate for the approach in 153 patients with femoral head fracture in 11 studies, and the frequency of AVN development was 3.67 times higher with the posterior approach than with the anterior approach and 2.24 times higher than that with TFO. Additionally, the frequency of post-traumatic arthritis was higher with the anterior and posterior approaches than with TFO by 20.3 times (p = 0.04) and 30.6 (p = 0.018) times, respectively . This proves that TFO is safe and provides a wide field of view for anatomic reduction and stable fixation.
The correlation between the time to femoral head reduction, which is known to influence functional outcomes, and the Pipkin classification was not statistically significant in the current study; however, a significant correlation was found between functional outcomes and age, associated acetabular fracture, AVN development, and radiologic results [4, 30]. This may be because older age is associated with more difficult postoperative rehabilitation, consequently, a longer time to return to daily activities. Moreover, the presence of an associated acetabular fracture with FHFD indicates serious hip joint damage due to high-energy injuries . Marchetti et al. found no significant difference in a comparative analysis of closed reduction within and after 6 h . This means that blood flow disturbance caused by femoral neck fractures has a large influence on the outcome .
In AVN diagnosis, SPECT/CT and MRI are useful methods; however, they have some limitations. MRI is currently the most accurate method for AVN diagnosis . Compared with simple radiography, MRI allows a much earlier diagnosis of necrosis, specifies the location and size of the lesions, which are crucial for a more accurate determination of prognosis or treatment, and aids in the differential diagnosis of subchondral stress fractures or transient osteoporosis of the hip joint (bone marrow edema syndrome); this may present a similar pattern to AVN. However, MRI is relatively expensive, and signal blurring caused by the metals used to fix the fracture site of the femoral head and acetabulum may interfere with accurate diagnosis . SPECT has higher accuracy than simple bone scanning; however, it does not specify the size or location of necrosis. To overcome this limitation, the SPECT/CT examination method, which combines SPECT and CT, was developed. This method evaluates the blood flow status in the bone while precisely localizing the necrotic site using CT, and it has a lower examination cost (by approximately one-third) than MRI. Additionally, the interference of implants is less than that present in MRI, thereby allowing for accurate examination even after implant insertion . Park et al. reported that SPECT/CT has a diagnostic value in predicting the occurrence of AVN after femoral neck fractures . When Ganz introduced the method for TFO, he devised it to solve the impingement that occurred in the femoral head or acetabulum, and AVN was confirmed by simple radiography . In this study, MRI or SPECT/CT was performed for the first time to accurately identify the lesion site for FHFD.
This study has several limitations. First, this was a retrospective study in which data were obtained from the patients’ medical records, and only patients with FHFD who underwent SHD were included. The incidence of AVN varied according to the patient’s age, sex, and severity of damage . In this study, there was a large difference in the number of male and female patients and a large age span among the study participants. Hence, a selective bias may have been introduced during data collection. Second, the incidence of FHFD (i.e., number of patients with FHFD treated at our hospital) was relatively low, no control group was included, and patient compliance was not considered. Third, the relatively short follow-up period may have limited our evaluation of the clinical and radiological outcomes in patients who were followed up for > 2.5 years. Nonetheless, we believe that our findings from an average follow-up of 5 years provide sufficient evidence for the effectiveness of SHD as a surgical technique, in view of Brav et al.’s report that 98% of AVN developed within 1 year in patients with traumatic hip dislocation .