Femoral head fractures are rare uncommon injuries, which typically occurs as a result of traumatic posterior dislocation of hip joint 11,20-23. In our study, 62% of these fractures resulted from motor vehicle accident, followed by 28% from injury due to fall. Early diagnosis and prompt concentric reduction are essential for successful management of these fractures 24. However, due to lack of established consensus on the diagnosis and treatment of femoral head fractures and limited number of cases reported in the literature, the prognosis of these injuries remains uncertain.
In this retrospective review, we evaluated the management, complication and outcome of fifty patients with femoral head fracture treated at a single institution from January 2011- December 2018. We used modified Harris hip score 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 were further investigated based on Pipkin Classification.
According to Pipkin classification 2-4 a relative increase of poor outcomes from Pipkin 1 to 4 (11% to 29% respectively) was noted. This observation is indicative for predictive value of pipkin classification which is also supported by the 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 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 femoral head 13. In addition, complication such as traumatic arthritis may develop due to poor reduction of fracture in the weight bearing area of the articular surface 25. Therefore, timely diagnosis and prompt accurate reduction of the associated hip dislocation should be performed to prevent further damage to peripheral vessels and improve outcome. Treatment measures were either operative or non-operative. Treatment approach and timing for recovery to each patient were dependent based on the fracture pattern and associated injuries. Using skeletal traction 6,26-28, which is frequently used as an initial management of femoral head fractures, 16% of cases in our study were managed non-operatively to decrease 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 11,29. Operative measure included fracture fixation using ORIF or total hip replacement (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%) fractures, while THR was performed mostly within Pipkin III fractures (37.5%).
The long-term follow-up analysis after operative (ORIF) or non-operative treatment regimens on Pipkin 1 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 better outcome than an operative intervention. Several studies support this non-operative management of Pipkin I fractures and controversies remain regarding surgical management of these fractures30-33. The fact that only 4 cases were managed non-operative, our finding could be attributed to statistical error. Thus we do not make absolute recommendation in favor of non-operative and against all other operative approaches, when dealing with Pipkin 1 factures, but, if head fractures are less than 1 mm, absence of loose bodies in the joint space, stable hip joint with good relation of head with glenoid34, non-operative intervention may be an adequate intervention.
Pipkin II fractures involves a larger portion of weight bearing femoral head surface and is more challenging injury 30. 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 fracture with anatomical reduction and surgical fixation 7,13,30.
Pipkin Type III fractures is the least frequent fracture types that involve dual insult to 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 best results (excellent or good). Although treatment options for Pipkin III fractures ranges from open reduction and rigid fixation to arthroplasty, the outcome is highly dependent on age and other variables. Generally, the young patients with Pipkin III fractures should be aimed at preserving the joints, while Total Hip Arthroplasty (THA) may be reasonable option for the elderly35,36. In our study, two (out of five) patients with Pipkin III fracture who were operated with fixation of fragment required conversion to secondary THR. This trend supports the opinion of published literature that postulates Pipkin III fractures as a predictive of secondary THR in femoral head fractures 5,37.
Pipkin IV injuries leads to 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 treatments methods. One of the particular characteristics about this injury group is that, despite of the type of intervention used, it is often challenging to address whether the approach should be directed to acetabulum, femoral head or both. These fractures require anatomical reduction and internal fixation of femoral head and acetabulum lesions with attention toward restorations of hip congruency and hip stability.
Despite advances in several surgical approaches for femoral head fracture management, controversy exists with regard to the choice of optimal surgical treatment. The anterior Smith-Petersen approach offers good exposure and easier access to the fracture head; and thus, it is more suitable for the treatment of Pipkin I and II femoral head fractures 38. 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 posterior Kocher-Langenbeck approach. However, the often-quoted disadvantage of the anterior- based approaches has been the association with increased heterotopic ossification3,9,12,39. Similarly, this approach has also been linked to further damage any residual anterior blood supply to the femoral head although, the anatomical studies does not support this theory 40,41. The posterior-based approach can provide direct visualization of the acetabular fracture and an opportunity for simultaneous repair of femoral head and acetabular fractures as seen in Pipkin type IV injuries. In this study, majority of patients with Pipkin I and II were treated using 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 anterior and posterior approach. 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.
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 of surgical approaches. The AVN is one of the main long-term complications secondary to iatrogenic insult or due to damage during the initial injury16. Clinical symptoms of AVN may present early (from 6 weeks) or late (several years following injury) with collapse of femoral head accompanied with PTA42. In our study, all patients who developed AVN showed poor functional outcome. While two patients who underwent 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 on incidence of AVN. Similarly, heterotopic ossification (HO) is one of most common complication after operative fixation, with an incident associated with anterior surgical approach 9,13,20. In our study, odds ratio analysis demonstrated a trend to a higher incidence of HO (all Brooker stages) after posterior approach relative to 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 fixation43. However, only eight (16%) of our patients who developed HO, all with a Brooker grade I, had no impact to the final functional outcome. Post-traumatic osteoarthritis is another most common complication of femoral head fracture management and its incidence is directly related to the severity of initial injury23. A higher incidence of PTA was found in 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 fractures that belonged to Pipkin type III (37.5%) and IV (43%) category.
Overall, our study has for the first time used modified Harris Hip (mHHS) score for clinical evaluation of femoral head fractures. Using mHHS, our study indicates that Pipkin classification of femoral head fractures can have a predictive value. Operative management using ORIF is carried out among majority of cases with Pipkin I and Pipkin IV fractures. Non-operative intervention may be adequate for Pipkin I fractures and should be recommended after thorough evaluation of the quality of fracture reduction, articular congruency, hip stability and the absences of loose fragments in joint space using modern imaging techniques. Anterior surgical approach has provided promising results with lower incidence of major complications in Pipkin I and II fractures, making it probably the best approach for operative management of Pipkin I and II fractures. The incidence of HO is also shown to be highly prevalent with posterior K-L approach. Despite of rigid and anatomical fixation, the degree of trauma with pipkin III or IV, creates complexity in physio-anatomical healing and poor functional outcome.