Program

P027

Poster

Bone graft of a femoral head by fragments of neurogenic heterotopic ossification

Mr Damien MOTAVASSELIa, Dr Aurélie DIEBOLDa, Dr Alexis SCHNITZLERa, Dr Philippe DENORMANDIEa, Dr Mélanie POPOFFa, Dr Francois GENÊTa

a Hopital Raymond Poincaré

Introduction
Neurogenic heterotopic ossification (NHO) are a common complication after lesions of the central nervous system (10-23% after head injury). The late removal of hip NHOs sometimes causes the risk of femoral head and femoral neck fracture per or postoperatively. Indeed ankylosis of a joint eventually induces bone loss and joint destruction.

Observation
A 23 year old patient who suffered a severe TBI in 2012 in a military context presents multiple NHOs, which especially affects both hips. On the right side, CT of the pelvis shows a circumferential NHO that ankyloses the joint. The NHO therefore absorbs the stresses on the femoral head which is thus off-loaded. This causes bone loss quantified by CT.
A surgical indication for excision is established for functional reasons and because of the risks of the sciatic nerve compression. A soft femoral neck is found during the procedure. A bone graft using the fragments of the NHO is attempted by internal drilling. The procedure ends with a sciatic nerve release. The rehabilitation program started after two weeks of strict bed rest in order to consolidate the bone graft. A passive mobilization program in flexion-extension is started afterward, with a gain of 10° every two weeks. Rotations and abductions-adductions are strictly prohibited during the first 6 weeks. Progressive verticalization is started after 2 months. A radiography of the pelvis shows the integrity of the femoral head 6 weeks after surgery. The patient is then placed in a wheelchair.

Discussion
The NHOs must be removed as soon as they are troublesome. Late surgery is exposing the patient to a joint ankylosis which complicates the surgical procedure and its aftermath. In this case, bone grafting the femoral head with fragments of NHOs seems to be an alternative to explore in order to avoid head-neck resection or the implantation of a hip replacement. However, an extremely cautious rehabilitation seems to be necessary.

References

1.Genet F, et al. Impact of late surgical intervention on NHO of the hip after traumatic neurological injury. JBoneJtSurgBr. nov2009;91(11):1493-8.

2.Carlier RY, et al. Ankylosing neurogenic myositis ossificans of the hip. An enhanced volumetric CT study. JBoneJtSurgBr. mars2005;87(3):301-5.

Keywords : Neurogenic heterotopic ossification, NHO, ankylosis, bone graft, rehabilitation, femoral head