Femoral head fracture is rare uncommon injuries, which typically occurs as a result of traumatic posterior dislocation of the hip joint [16, 26–28]. Early diagnosis and prompt concentric reduction are essential for the successful management of these fractures [29]. However, due to a lack of established consensus on the diagnosis and treatment of femoral head fractures and a limited number of cases reported in the literature, the prognosis of these injuries remains uncertain.
In this retrospective study, we evaluated the management, complication, and outcome of femoral head fracture. We used MHHS to evaluate the functional outcome. Our study found an overall outcome of excellent in two patients, good in sixteen patients, fair in twenty-two patients, and poor in eleven patients. The association between functional outcome, treatment approaches, and complications was further investigated based on Pipkin Classification.
According to the Pipkin classification [3–5], a relative increase of poor outcomes from Pipkin 1 to 4 (11–29% respectively) was noted. Our study also indicated similar outcomes classification-wise supported by statistical significance. While these observations were in a small cohort of patients, they do suggest the importance of pipkin classification in predicting less favorable outcomes with an associated femoral head fracture.
The particularity of Femoral Head fractures and Prognostic Factors
The femoral head fracture with hip dislocation is a true emergency in orthopedic trauma. Long-term fracture and dislocation of the femoral head will damage the blood supply of the femoral head, leading to subsequent avascular necrosis of the femoral head [18]. In addition, a complication such as traumatic arthritis may develop due to poor reduction of fracture in the weight-bearing area of the articular surface [30]. Therefore, timely diagnosis and prompt reduction of the associated hip dislocation should be performed to prevent further damage to peripheral vessels and improve outcomes. Treatment measures were either operative or non-operative. The treatment approach and timing for recovery for each patient were dependent based on the fracture pattern and associated injuries. Using skeletal traction [9, 31–33], which is frequently used as an initial management of femoral head fracture, 16% of cases in our study were managed non-operatively to decrease the risk of chondrolysis. The criteria for non-operative intervention were determined based on anatomic reduction of hip dislocation and femoral head fracture, intraarticular fragment displacement of less than 1 cm, absence of bone or cartilaginous fragment in the joint space, and hip stability. Those fractures that did not meet such criteria were treated operatively [8, 16]. The operative measure included fracture fixation using ORIF or THR. Operative management is generally preferred when the fracture is severe and extends superior to the fovea. In our study, ORIF was mainly rendered to Pipkin II (80%) and Pipkin IV (79%) fracture, while THR was performed mostly within Pipkin III fracture (37.5%).
The long-term follow-up analysis after operative (ORIF) or non-operative treatment regimens on Pipkin I injuries demonstrated that the best results (80% excellent or good) were accomplished. Although a statistical difference was not found (P = 0.59), the non-operative intervention seems to result in a better outcome than an operative intervention. Several studies support this non-operative management of Pipkin I fracture and controversies remain regarding the surgical management of these fractures [34–37]. The fact that only 4 cases were managed non-operative. Thus, we do not make an absolute recommendation in favor of non-operative when dealing with Pipkin 1. However, when the head fractures are less than 1 mm, absence of loose bodies in the joint space, stable hip joint with good relation of the head with the glenoid[38], non-operative intervention may be an adequate intervention. Pipkin II fracture involves a larger portion of the weight-bearing femoral head surface and is a more challenging injury [34]. The majority (80%) of these fractures were operated with internal fixation of the fragment. This is in line with current principles of managing Pipkin II fractures with anatomical reduction and surgical fixation [11, 18, 34].
Pipkin Type III fracture is the least frequent type that involves dual insult to the femoral head and neck. All eight of our Pipkin III injuries underwent operative intervention, using ORIF and/or THR, while none of the patients demonstrated the best results (excellent or good). Although treatment options for Pipkin III fracture range from open reduction and rigid fixation to arthroplasty, the outcome is highly dependent on age, delay in surgery, and degree of comminution. Generally, young patients with Pipkin III fractures should be aimed at preserving the joints, while THR may be a reasonable option for the elderly[6, 39]. In our study, two (out of five) patients with Pipkin III fracture who were operated on with fixation of fragment required conversion to secondary THR. This trend supports the opinion of published literature that postulates Pipkin III fracture as a predictive of secondary THR in femoral head fracture [7, 40].
Pipkin IV injuries lead to the worst outcome as they involve both the femoral head and the acetabulum. A majority of our patients with Pipkin IV injuries were treated with ORIF, however, there was no significant improvement in outcome among different treatment methods. One of the particular characteristics of this injury group is that, despite the type of intervention used, it is often challenging to address whether the approach should be directed to the acetabulum, femoral head, or both. These fractures require anatomical reduction and internal fixation of the femoral head and acetabulum lesions with attention toward restorations of hip congruency and hip stability.
Femoral Head Fracture and Significance of Surgical Approach
Despite advances in several surgical approaches for femoral head fracture management, controversy exists concerning the choice of optimal surgical treatment. The anterior S-P approach offers good exposure and easier access to the fractured head; thus, it is more suitable for the treatment of Pipkin I and II femoral head fractures [41]. Such an anterior approach can significantly reduce blood loss and operation time, and therefore reduce the incidence of avascular necrosis of the femoral head, compared to the posterior K-L approach. However, the often-quoted disadvantage of the anterior-based approaches has been the association with increased heterotopic ossification[4, 13, 17, 42]. Similarly, this approach has also been linked to further damage to any residual anterior blood supply to the femoral head although, the anatomical studies do not support this theory [43, 44]. The posterior-based approach can provide direct visualization of the acetabular fracture and an opportunity for simultaneous repair of the femoral head and acetabular fracture as seen in Pipkin type IV injuries. In this study, the majority of patients with Pipkin I and II were treated using the anterior approach while the posterior was mainly used in Pipkin III and Pipkin IV fractures. Correlation analysis showed no statistical difference (p > 0.05) in outcome between the anterior and posterior approaches. Although it should be noted that irrespective of our findings, the choice of surgical approach and outcome is frequently determined by the fracture pattern and the overall injury severity characteristics.
Factors Regarding Complications and Outcomes
Regarding major complications, our findings suggest that the likelihood of AVN is higher when a lateral approach is used. This could be due to the severity of Pipkin III injuries and the confounding factors such as displaced femoral neck fracture, damage to vascular structures, and inadequate reduction that mostly leads to subsequent AVN despite surgical approaches. The AVN is one of the main long-term complications secondary to iatrogenic insult or due to damage during the initial injury[22]. Clinical symptoms of AVN may present early (from 6 weeks) or late (several years following injury) with the collapse of the femoral head accompanied by PTA[45]. In our study, all patients who developed AVN showed poor functional outcomes. While two patients who underwent a posterior approach for ORIF developed AVN. It is important to note that our mean follow-up time may be too short to capture all patients who develop clinical symptoms of AVN and thus longer follow-up times are required for detailed analysis of the incidence of AVN. Similarly, HO is one of the most common complications after operative fixation, with an incident associated with the anterior surgical approach [13, 18, 26]. In our study, odds ratio analysis demonstrated a trend to a higher incidence of HO (all Brooker stages) after the posterior approach relative to the anterior one, which was statistically not significant. Although it is unclear, this result could be implicated due to extensive surgical dissection of gluteal muscles during fixation[46]. However, only eight (16%) of our patients who developed HO, all with a Brooker grade I, had no impact on the final functional outcome. Post-traumatic osteoarthritis is another common complication of femoral head fracture management and its incidence is directly related to the severity of the initial injury[28]. A higher incidence of PTA was found in the case of a posterior or lateral approach respectively versus an anterior approach. This finding, however, could be attributed to the fact that majority of the patients who developed PTA had fracture that belonged to Pipkin type III (37.5%) and IV (43%) category.
Overall, our study has for the first time used a modified Harris Hip (MHHS) score for the clinical evaluation of femoral head fracture. Operative management using ORIF is carried out in the majority of cases with Pipkin I and Pipkin IV fracture. Non-operative intervention may be adequate for Pipkin I fracture and should be recommended only after acceptable evaluation of the fracture reduction, articular congruency, hip stability, and the absence of loose fragments in joint space using modern imaging techniques. The anterior surgical approach has provided promising results with a lower incidence of major complications in Pipkin I and II fracture, making it probably the best approach for operative management of Pipkin I and II fracture. The incidence of HO is also shown to be highly prevalent with the posterior K-L approach. Regardless of rigid and anatomical fixation, the degree of trauma with pipkin III or IV creates complexity in physio-anatomical healing and poor functional outcome.
This study was subject to several limitations. Firstly, this study was small in size for a single center. Secondly, the study enrolled a small number of patients treated with a different approach. Thirdly, the power of the statistics was low due to the lack of a higher number of enrolled patents, different approaches, and management. Relatively short follow-up duration was also a limitation of this study because it might be insufficient to assess post-traumatic osteoarthritis. Therefore, it is important to conduct a large prospective study using validated outcome scores, that will develop the fracture classification and operative approaches.