Bone Marrow Lesions of the Hip - Avascular Necrosis and Subchondral Cyst
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This lecture discusses avascular necrosis of the femoral head. It covers AVN causes, diagnostic workup with MRI, CT and X-ray examples, surgical and non-surgical management of AVN and includes an AVN case study. It also covers periacetabular subchondral cysts and subchondroplasty with a case study.
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Bone Marrow Lesions of the Hip - Avascular Necrosis and Subchondral Cyst
- 1. Bone Marrow Lesions of the Hip AVN and Subchondral Cyst SportsMed Innovate – 9/25/19 Benedict U. Nwachukwu MD MBA Attending Surgeon Hospital for Special Surgery Clinical Instructor Weill Cornell Medical School Co-Director for Clinical Research HSS SMI
- 3. 3 Avascular necrosis femoral head Femoral head avascular necrosis (AVN) defined as bone cell death that follows an impairment of the blood flow to the bone from a traumatic or non-traumatic origin Swedish and Australian Registries – 6- 12% of all primary total hip replacements Early diagnosis and management is critical Clinical presentation can be quite non specific
- 4. 4 AVN Causes Osteonecrosis of the femoral head: pathophysiology and current concepts of treatment – Petek et al. 2019
- 6. 6 MANAGEMENT MEDICAL o Statins/Enoxaparin o Promising results in very early disease for patients with hypercoagulopathies o Bisphosphonates (alendronate ) Prevents femoral head collapse in osteonecrosis with subchondral lucency o Hyperbaric oxygen therapy (HBO) Thought to reverse cellular ischemia
- 7. 7 MANAGEMENT SURGICAL o Core Decompression alone o Vascularized and Non- vascularized bone graft o Proximal femoral osteotomies o Total Hip Replacement o Arthroscopic assisted core decompression with structural support and biologic augmentation
- 8. 8 Case Presentation – AVN 51 year old female with ongoing right hip pain No relief with 2 x CSIs Limited hip flexion, adduction and internal rotation on exam XR with concentric hip joint, otherwise unremarkable
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- 10. 10 Diagnostic Arthroscopy: Normal chondrolabral interface Softening of the femoral head
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- 12. 12 Sample delivery system for a commercially available option Can be mixed with saline or bone marrow aspirate (BMA) Non-published data suggestive of improved osseous integration when mixed with BMA Images courtesy of Arthrex BoneSync
- 13. What about sub-chondral problems on the other side of the socket?? 13
- 14. Management of periacetabular subchondral cysts 14
- 15. Is there a role for subchondroplasty in the hip? 15 2019 Subchondroplasty provides symptomatic pain relief in the knee – can we apply principles to the hip?
- 16. 16 47 year old female with persistent right hip pain Mild limitations in hip range of motion with some hip impingement signs Failed physical therapy 1 month relief with hip injection Case Presentation – AVN
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- 19. 19
- 20. THANK YOU
Editor's Notes
- Avascular necrosis of the femoral head is a condition in which the subchondral bone loses its viability. The condition is characterized by a compromised subchondral microcirculation, especially in the small retinacular vessels, which ultimately leads to necrosis of bone. An accumulation of micro-injuries is seen and, as there is no bone remodelling, a collapse of the subchondral bone occurs In the United States epidemiological data suggests that the incidence of femoral head AVN is between 300 and 600 thousand new cases each year and in well established registries including the Swedish and Australian registries femoral head AVN accounts for between 6 and 12% of all primary total hip replacements Given the incidence, early diagnosis and management is critical however the clinical presentation can often be quite non specific
- It is important to remember that femoral head AVN can be either traumatic or atraumatic in nature. Traumatic causes include hip dislocation and proximal femur fracture The most common cited risk factors however are corticoid administration and alcohol intake. Steroid administration causes AVN by various mechanisms but the most significant of which is that alcohol induces a vasoconstriction and leads to an increase of a procoagulant factor production. Alcohol consumption causes AVN by altering mesenchymal differentiation and many studies had shown that there is a reduced ability to differentiate toward an osteoblastic lineage. And finally, hypercoagulable states induce AVN through altered blood flow
- Imaging modalities in hip AVN range from MRI to XRs and CTs. In my practice – MRI is the gold standard for detecting pre-collapse lesions and differentiating between osteopenia and femoral head bruises. CT has a limited role and is better for evaluating already advanced head collapse
- Although this is largely a surgical audience it is always worthwhile noting that there are medical options that do exist in the treatment of femoral head avascular necrosis On the non-traumatic pathway, there are some medications that have been proposed to be started before critical ischemia occurs and these consist of the use of statins or enoxaparin to prevent, first, endothelial dysfunction and, second, thrombosis formation. Bisphosphonates – specifically Alendronate have been shown to have beneficial effects in early hip avascular necrosis. The proposed mechanism of action is that bisphosphonates slow down osteoclastic resorption of necrotic bone during repair, thereby helping in maintaining femoral head sphericity and allowing for the revascularization and prevention of the collapse of the femoral head Hyperbaric oxygen therapy (HBO) has also been postulated to reverse cellular ischemia and to diminish the inflammatory response for the symptomatic early stage ONFH
- The gold standard surgical treatment for femoral head AVN is a core decompression. The procedure is theorized to reduce the intraosseous pressure as well as to restore the vascular inflow of the femoral head. The original technique was described by Ficat in 1985 and they reported a 90% success rate Bone grafting is theoretically supposed to be superior to CD alone because it gives a structural support to the remaining subchondral bone that has been decompressed. Techniques for bone grafting with a vascular pedicle have also been described however these techniques do have associated complications and require microvascular expertise Some authors may counsel for proximal femoral osteotomy in select patients as a way of offloading the necrotic bone segment and providing symptomatic relief. It is worth noting though hip replacements performed after these osteotomies have been shown to have less favorable results In advanced cases of femoral head collapse with recalcitrant pain – a total hip replacement is the most established and reliable treatment Over the next few slides I am going to give my technique for addressing pre-collapse femoral head AVN. I prefer an arthroscopic assisted core decompression with structural support and biologic augmentation.
- This is that patient’s MRI which avascular necrosis of the anterosuperior femoral head without evidence of subchondral collapse Based on this finding and persistent pain, the decision was made to proceed with hip arthroscopy and core decompression
- A standard hip arthroscopy with an anterolateral and a modified mid anterior portal used I will initially perform a diagnostic arthroscopy to evaluate the cartilage and labrum. In this case there is no labral abnormality and I am able to use my probe to palpate the area of femoral head avascular necrosis. If softening or delamination is present, a chondroplasty or microfracture is performed based on the size, stability, and depth of the lesion. This is typically performed through the anterior portal while one is visualizing through the AL portal. In this case there was no evidence of that
- Core decompression is then performed through a separate 3-cm incision distal and posterior to the AL portal. This incision is localized and the trajectory is confirmed under fluoroscopic guidance. The probe is also use for triangulation of the lesion First a guide pin is advanced to 1 to 2 mm deep to the subchondral bone – this the image in the upper left A soft-tissue guide is placed over the guide pin, and a reamer is advanced to the same depth. Obviously you have to be careful to not advance the pin as you ream – for this case we used the Wright Medical Core Decompression system but there are a number of viable options. Tactile feedback can be helpful here as you know that you are in the sclerotic bone as it will get considerably harder Once in the sclerotic bone – I will often introduce a curved curette to remove any residual necrotic bone Depending on the system that you are using, a syringe can then be inserted into the reamed canal to inject a synthetic agent into the femoral head. In this case we used a synthetic putty that is a combination of calcium phosphate (CaPO4) and calcium sulfate (CaSO4). Some of the other commercially available alternatives provide a collagen additive that is theorized to provide the ability for native boney ingrowth
- This is an example of the kit for one of the commercially available options – most options will have some kind of kit for delivery and some options will allow you to mix in bone marrow aspirate with the putty. The theoretical benefit of this obviously is that there is increased potential for osseous integration and regrowth
- We re going to change pace now and talk about management strategies for subchondral damage on the acetabular side
- In contrast to femoral head AVN and subchondral disease of the femoral head we have traditionally had limited treatment options for patients with periacetabular subchondral disease. This MRI is representative of a patient that can present a treatment challenge. Often these patients will have maintained joint spaces and will not yet be ready for a hip replacement but may have joint degeneration that would limit their outcome from traditional hip arthroscopy with osteochondroplasty
- Symptoms – onset is variable, usually have history of chronic, mild discomfort Alternative/coexistent etiologies – impact treatment algorithm History of dysplasia/disorders – also impacts treatment approach
- Symptoms – onset is variable, usually have history of chronic, mild discomfort Alternative/coexistent etiologies – impact treatment algorithm History of dysplasia/disorders – also impacts treatment approach
- Symptoms – onset is variable, usually have history of chronic, mild discomfort Alternative/coexistent etiologies – impact treatment algorithm History of dysplasia/disorders – also impacts treatment approach