Evaluation of the muscle morphology of the obturator externus and piriformis as the predictors of avascular necrosis of the femoral head in acetabular fractures.

Lalit Maini,Sahil Batra,Sumit Arora,Santosh Kumar,Rajat Gupta

doi:10.1007/s11751-016-0253-7

Lalit Maini, Sahil Batra + Show 3 more

Open Access

https://doi.org/10.1007/s11751-016-0253-7

Copy DOI

Abstract

Avascular necrosis (AVN) of femoral head is a recognised complication of fracture dislocation of the hip joint but is not studied frequently in relation to acetabulum fractures. The aim was to establish the relationship between obturator externus and piriformis muscle morphology in acetabulum fractures and potenital development of AVN of the femoral head. Twenty-five fractures were included in this prospective study and were subjected to radiological assessment and computed tomography of the pelvis. Magnetic resonance imaging (MRI) of the hip was performed to assess the morphology of obturator externus and piriformis, and findings were compared intraoperatively (in 15 cases). Serial radiographs were taken at monthly intervals to assess the development of avascular necrosis. The patients with no evidence of AVN on radiographs at 6 months had additional MRI scans to look for such changes. Three patients developed AVN of femoral head and two had complete tears of piriformis and/or obturator externus muscles on the pre-operative MRI with the findings confirmed intraoperatively (p = 0.013). None of the patients without changes of AVN at 6-month follow-up had complete tears of either or both muscles. Of these patients, there was one case each of T-type fracture, isolated posterior wall fracture with hip dislocation, and posterior wall with transverse fracture of the acetabulum. Complete tears of obturator externus and/or piriformis muscles are a strong predictor of future development of AVN of the femoral head.

Highlights

Acetabular fractures result from high-energy trauma in which soft tissues around the involved hip are severely affected
The aim was to establish the relationship between obturator externus and piriformis muscle morphology in acetabulum fractures and potenital development of Avascular necrosis (AVN) of the femoral head
The morphology of piriformis and obturator externus was examined in 10 cases that were operated with Kocher– Langenbeck approach and the findings compared with the pre-operative Magnetic resonance imaging (MRI)

Summary

Introduction

Acetabular fractures result from high-energy trauma in which soft tissues around the involved hip are severely affected These cases may, at times, be associated with dislocation of the hip joint and lead to avascular necrosis (AVN) of femoral head potentially. The relevant nutrient vessel to the femoral head in adults is the deep branch of the medial femoral circumflex artery (MFCA) [11] It may be injured during the posterior approach to the hip and acetabulum. Gautier et al [11] stated the piriformis branch might play a role in vascularisation of the femoral head after injury of the deep branch of the MFCA They observed the obturator externus muscle protects the MFCA when the hip is dislocated. We investigated the possible association of acetabular fracture pattern on development of AVN of the femoral head

Patients and methods

Results

Conclusion

Compliance with ethical standards