Early Versus Delayed Hip Reduction in Treating Femoral Head Fracture Combined With Posterior Hip Dislocation: A Comparative Study

Background: Few studies focus on the treatment of femoral head fracture combined with posterior hip dislocation, and the the safe interval time between injury and reduction still remains controversial. The purpose of this study was to evaluate and compare the outcome of early and delayed hip reduction in treating femoral head fracture combined with posterior hip dislocation. Methods: A total of 71 patients were evaluated in this retrospective study. Based on the time to hip reduction, they were divided into early group (within 6 hours after injury) and delayed group (between 6 12 hours after injury). The two groups were compared in reference to hospital day, fracture healing time, the occurrence of complications and nal functional outcome. The Thompson-Epstein criteria, modied merled’ Aubigne-Postel scores, visual analog scale (VAS) and Medical Outcomes Short Form 12-item questionnaire score (SF-12) were used for nal functional evaluation. Results: The mean hospital day and fracture healing time in the early group were signicantly lower than delayed group. The incidence of infection, post-traumatic osteoarthritis, and avascular necrosis of the femoral head (ANFH) in the delayed group were higher than early group. The early group had better functional outcomes in term of Thompson-Epstein criteria, modied merled’ Aubigne-Postel scores and physical component scale (PCS) than delayed group. Conclusions: For the treatment of femoral head fracture combined with posterior hip dislocation, the early and prompt hip reduction can effectively facilitate the fracture healing and patient recovery as well as obtain better functional outcomes.


Background
Femoral head fractures are relatively infrequent injury, occurring often following traumatic posterior hip dislocation [1,2]. As reported in previous literature, approximately 15% femoral head fractures were associated with posterior hip dislocation [1,3,4]. In 1957, Pipkin proposed the Pipkin classi cation for femoral head fractures combined with posterior hip dislocation, witch based on the location of the fracture line relation to the fovea and the potential presence of the femoral neck or acetabulum [5].
Because of the Pipkin classi cation was widely used for clinical work, which greatly contributed to the understanding of femoral head fractures, the femoral head fractures combined with posterior hip dislocation is therefore also called Pipkin fractures [3].
Owing to the complexity of the hip anatomy, the treatment of femoral head fractures is particularly di cult. Although some studies have reported satisfactory results with nonsurgical treatment in the nondisplaced Pipkin type I and type II fractures, this treatment has been almost abandoned because of the high rate of complications associated with longstanding patient immobility and the high cost of prolonged admission [1,[6][7][8][9]. Nowadays, more and more investigators recommend surgical treatment of femoral head fractures [2]. For an optimal outcome, there should be anatomic joint reconstruction, restoration of the hip congruency and fracture stabilization to facilitate union [1,2].
In cases of femoral head fractures combine with posterior hip dislocation, the early and prompt hip reduction is associated with a good results [1,2,10,11]. However, because of the the relatively infrequent and limited numbers of patients, there is still no consensus on the reduction timing of posterior hip dislocation in treating femoral head fracture-dislocations [2,12]. Although some reports showed that the good results can be achieved when hip reduction was performed within 12 hours or 24 hours, some authors emphasize that the posterior dislocation of hip joint should be reduced within 6 hours [7,[13][14][15].
The purpose of this study was to compare the outcome of early and delayed hip reduction in treating femoral head fracture combined with posterior hip dislocation, with the objective of de ning the best timing reduction.

Study design
After obtaining approval from our institutional review board, we retrospectively reviewed patients who

Interventions
All patients presented to our emergency department and then were assessed according to the Adult Trauma Life Support (ATLS™) guidelines, including a hip anteroposterior radiograph and threedimensional computed tomography examination. The emergency closed reduction of posterior hip dislocation was attempted under general anaesthesia by Allis method in operating room [16]. If the hip can not be reduced closed or the concentric reduction cannot be achieved, an open reduction was performed immediately. After successful reduction of posterior hip dislocation, the skeletal traction was essential to maintain the reduction, and the fractures were treated operatively within 72 hours.
All surgeries were performed under general anesthesia by one surgical team consisting of 2 senior orthopaedics surgeons. The modi ed Heuter anterior approach or posterior Kocher-Langenbeck approach as previously described was chosen for Pipkin type I and type II fractures, and the Kocher-Langenbeck approach was applied for Pipkin type III and type IV fractures [9,11]. The fractures reduction were performed under intraoperative uoroscopy, small or comminuted fragments of the femoral head were removed and the large fragments or fragments within the weight-bearing portion were reduced anatomically and xed with bioabsorbable screws or cannulated screws. The femoral neck fractures were reduced and xed with cannulated screws, the acetabular fractures were reduced and xed with reconstruction plates plus screws.
After operation, the prophylactic intravenous antibiotics were administered for 24 hours, and low molecular weight heparin were given to prevent deep venous thrombosis. The drainage was maintained for 24-48 hours and then was removed. Limb functional exercises were encouraged after recovery from anesthesia. All patients were instructed to non-weight bearing for six to eight weeks initially, and then gradually increased to partial weight-bearing. Once the radiographs showed bone union, full weight bearing was started. All patients would be followed at monthly until the radiographic bony union, and then at annually until the last follow-up. Serial radiographs were obtained at every follow up, and the complication were recorded.

Statistical analysis
All data management and statistical analysis were performed with Statistical Package for the Social Sciences (SPSS 20.0, IBM, New York City, USA). Categorical data were tabulated with frequencies or percentages, and continuous data were expressed as the mean ± standard deviation(SD). Normality was tested using the Kolmogorov-Smirnov test. Independent t-tests were used for normally distributed continuous data and the Mann-Whitney test was used to compare abnormally distributed continuous data between two groups. Chi-square test or Fisher exact test was used to analyze the categorical variables. The level of signi cance was set at p<0.05.

Baseline characteristics
A total of 71 patients were evaluated in this retrospective study, the posterior hip dislocation were reduced within 6 hours after injury in 39 patients (early group), and 32 patients were reduced between 6 -12 hours after injury (delayed group). All patients were attempted to closed reduction in the operating room by Allis method, three cases in early group and ve cases in delayed group required open reduction after the failure of closed reduction. The mean time between injury to the reduction of posterior hip dislocation in early group was 4.2 ± 1.2 hours, which was signi cantly lower than the delayed group (10.0 ± 1.6 hours). The mean operative time for the early group was 146.5 ± 48.0 minutes and for the delayed group was 147.3 ± 54.6 minutes. The estimated blood loss was 305.6 ± 179.6 ml for the early group and 350.7 ± 214.3 ml for the delayed group. There was no statistically signi cant differences between the two groups in terms of Pipkin classi cation, age, gender, side, causes, reduction method of dislocation, Surgical approach, operative time, blood loss and follow-up duration. The baseline characteristics of the patients were showed in Table 1.   (Table 2).

Discussion
The main mechanism of injury for Pipkin fracture-dislocations is traumatic posterior hip dislocation, as a result, the early and prompt hip reduction is particularly important [1,2,4,10,20]. In general, operating room closed reduction under anesthesia or sedation is the most common method. In recent years, more and more evidences show that urgent closed reduction in the Emergency Department is also an effective and safe method [1,21]. The most widely used reduction method for posterior hip dislocation is Allis manoeuvre, however, because of the residual intra-acetabular incarceration of the fracture fragments and soft tissue, failed closed reduction of posterior hip dislocation are not uncommon [22]. Chen et al. [20] reported a modi ed Allis manoeuvre which can effectively relieve the bony incarceration of the femoral head, and achieve closed reduction in ve Pipkin type I femoral head fracture cases who had experienced failed closed reduction via the Allis method. If the closed reduction fails or the concentric reduction cannot be achieved, the open reduction should be performed immediately. In our study, all patients were attempted to closed reduction in the operating room by Allis method, eight patients (three cases in early group and ve cases in delayed group) required open reduction after the failure of closed reduction.
While lots of evidences suggested that the time to hip reduction in a femoral fracture-dislocation is critical, the safe interval time between injury and reduction still remains controversial [10,23]. Early research suggested that the posterior hip dislocation should be reduced within 24 hours, otherwise the prognosis will be poor [14]. However, more and more studies reported that reduced within 6 hours help to minimize the incidence of complications and achieve a good result [15,23]. There is also evidence that good results were achieved when reduction was performed within 12 hours [13].
In our study, we found that the early reduction of posterior hip dislocation within 6 hours could facilitate fractures healing. Femoral head fractures often accompanied by severe bone and soft tissue damage, and the prolonged posterior hip dislocation will caused vasospasm, which further damage the blood supply of the femoral head and in uence the healing of fractures [1,2,10,23,24]. Early reduction of dislocation may recover earlier blood supply to the site of fractures by relieving tension across the femoral and circum ex vessel, which is bene cial to fracture healing [23]. Besides, our research also showed that the early reduction could shorten mean length of hospital stay, there might be several reasons for this. On one hand, the severe damage of soft tissue and blood supply cause by longer time dislocation may affect the healing of incision, which might increased the length of hospital. On the other hand, the dislocation of hip joint would aggravate the swelling of soft tissue and further affect the recovery of limb function.
The common complications of femoral head fractures included post-traumatic osteoarthritis, HO, ANFH and nonunion. The incidence of post-traumatic osteoarthritis is approximately 20%, which is related to the reduction quality of fracture and posterior hip dislocation [11]. Our data showed that the incidence of post-traumatic osteoarthritis is lower when reduction was performed within 6 hours. Similarly, prolonged dislocation of hip joint may have been associated with a higher rate of ANFH [10,24,25]. Mehlman et al.
[26] reported that patients whose reduction was delayed greater than 6 hours had a 20 times higher risk of having avascular necrosis develop compared with patients whose hips were reduced in 6 hours or less.
A meta-analysis showed that early reduction of posterior hip dislocation within 6 hours have a lower rate of osteonecrosis of the femoral head compare with delayed dislocation (over 6 hours from the time of injury) [23]. Our study also emphasize this point once again. At the nal follow up, the function evaluation showed that a better functional outcome can be obtained in early group.
There are several limitations to our study. One of the limitations is that this was a retrospective study. Second, our data was based on the clinical records, there may be some margins of error in the exact time from injury to hip reduction. Furthermore, the length of follow up is relatively insu cient, the longer follow-up was needed to further assess the long-term effects of reduction timing of posterior hip dislocation in treating femoral head fractures combined with posterior hip dislocation. We also found that some patients failed to complete the reduction of posterior hip dislocation within six hours because of the untimely transportation, therefore it is necessary to develop and improve the transport systems so as to transport such patients to the nearest trauma center immediately. This study was the rst report focusing on femoral head fractures combined posterior hip dislocation comparing the outcomes between the early reduction (within 6 hours after injury) with the delayed reduction (between 6 -12 hours after injury) of posterior hip dislocation.

Conclusion
In summary, in patients with femoral head fractures combined with posterior hip dislocation, the early and prompt hip reduction within 6 hours can effectively facilitate the fracture healing and patient recovery as well as obtain better functional outcomes. At the same time, our study indicate an association between early hip reduction and lower rate of complications in treating femoral head fractures combined with posterior hip dislocation.

Declarations
Ethical approval: The study was approved by the ethical committee of West China Hospital, Sichuan University. All procedures performed in studies involving human participants were in accordance with the ethical standards of institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.Written informed consent was obtained from all patients included in this study.  A-27-year-old woman with right Pipkin type III fracture, the emergency reduction of dislocation was performed within 6 houres after injury(A), Post-operative (B) and follow-up (C and D) radiographs demonstrating an bony union.