AVASCULAR NECROSIS OF THE FEMORAL HEAD

Moderator:

Presented by:

Avascular Necrosis (AVN) of the femoral head is a pathological process that results from interruption of the blood supply to the bone.

Also known as Osteonecrosis/ Osteochondritis Dissecans/ Chandler’s Disease

First described by Munro in 1738.

In 1835 Curveilhier depicted femoral head morphological changes secondary to interruption of blood flow.

First large sample size report by Mankin in 1962.

Traumatic

Non Traumatic

AVN

!!Compromise of the already tenuous blood supply!!

EPIDEMIOLOGY

10-25% of traumatic hip dislocations, risk with duration.

Non displaced femoral neck fractures 10%.

Displaced femoral neck fractures 15-50%.

True incidence of atraumatic AVN unknown but 5-18% of THR’s performed in US are for AVN.

Men:Women = 4:1

OA in relatively young patients; mean age at presentation: 38y.

Atraumatic AVN is bilateral in 30-70% but typically asymmetrical.

BLOOD SUPPLY OF FEMORAL HEAD

ETIOLOGY

Mechanical interruption of blood supply in traumatic cases.

Precise genesis of atraumatic AVN is unclear. It is hypothesized that various etiological factors:

Compromise the blood supply of the subchondral bone

Direct toxic effect on cells, with cellular necrosis and impaired remodeling potential of the subchondral bone with eventual collapse.

TRAUMATIC

Displaced hip fractures

Hip dislocation

Iatrogenic sec. to anterograde nailing

ATRAUMATIC

Most are Idiopathic.

Corticosteroids

90%Atraumati

cAVN

Alcohol Abuse

High dose oral corticosteroid regimens have a stronger association.

Quantifying amount of alcohol intake that increases risk of AVN has been problematic.

A prospective study suggests patients consuming 400ml of alcohol per week were 9.8 times more likely to develop AVN.

Smoking

Thrombophilias

Renal Osteodystrophy

Solid Organ Transplantation

Haemoglobinopathies

HIV infection

Gaucher Disease

Hyperlipidemia

Pancreatitis

Radiation Therapy

Chemotherapy

Liver Disease

Gout

SLE

Caisson Disease

PATHOPHSIOLOGY

Exact mechanism of atraumatic AVN not clearly defined.

Intraosseous vascular factorsI. Arterial factorsII. Venous factors

Intravascular

Intraosseus Factors

Capsular factors

Extravascular

EXTRAOSSEUS VASCULAR FACTORS

ARTERIAL FACTORS

Most important

Femoral Head blood supply is an End-Organ System with poor collateral development

Trauma to the hip may lead to contusion or mechanical interruption to the Lateral Retinacular Vessels (main blood supply of the femoral head & neck)

INTRAOSSEUS VASCULAR FACTORS

ARTERIAL FACTORS

Circulating microemboli that block the microcirculation of the femoral head

In conditions like-

1. Fat emboli (hyperlipidemia associated with alcoholism)

2. Steroid therapy3. Sickle Cell Disease4. Nitrogen bubbles in Caisson Disease

INTRAOSSEUS VASCULAR FACTORS

VENOUS FACTORS

Enlargement of intramedullary fat cells or fat-loading osteocytes causes the cells to expand; this may be the most significant factor l/t obstruction of venous drainage

Reducing venous outflow & causing stasis

S/i Caisson disease & SCD

EXTRAVASCULAR FACTORS

INTRAOSSEUS FACTORS

Ficat et al demonstrated increased bone marrow pressure in

the femoral necks of a large number of patients with

avascular necrosis of the femoral head (AVN).

Steroid

Hypertrophy of Fat cellsGaucher cells & Inflammatory cells

Encroach on intraosseous capillaries

Intramedullary circulation

Compartment syndrome

Alcohol & Steroid

Direct toxic metabolic effect on osteogenic cells

EXTRAVASCULAR FACTORS

CAPSULAR FACTORS

Trauma, Infection & Arthritis

Effusions within the Hip joint

Intracapsular Pressure

Tamponade of the LEVs

HISTORY

Non specific signs and symptoms

Early Painless.

Ultimate presentation Pain and

limitation of motion.

Mostly localized to groin area but may also

manifest in the ipsilateral buttock, knee or

greater trochanter region.

Mechanical Pain

PHYSICAL

Passive ROM limited and painful, esp. forced internal rotation.

Distinct limitation of passive abduction.

SLR against resistance provokes pain.

“Log-roll” may elicit pain consistent with active capsular synovitis.

Patients with chronic symptoms may have flexion contractures.

WORKUP

Labs:

Various investigations depending upon the suspected etiology

IMAGING STUDIES

X-rays:

A-P and frog-leg lateral (cross table lateral is less satisfactory)

Early changes not visible but, over time, a predictable pattern of radiographic change becomes evident.

Steinberg ME. Diagnostic imaging and role of stage and lesion size in determining outcome in osteonecrosis of the femoral head. Tech Orthop. 2001;16:6–15.

NECROTIC ANGLE OF KERBOULNecrotic angle >200 degrees Less favorable outcomes with certain head sparing procedures.

MRIo Most Accurate

o 1.5-T magnet 88% sensitivity 100% specificity 94% accuracy 

(Beltran et al)

o Indispensable for Accurate Staging of AVN because images clearly depict

Size of the lesion Gross estimates of stage

Avascular necrosis of the femoral head: high-field-strength MR imaging with histologic correlation.Lang P, Jergesen HE, Moseley ME, Block JE, Chafetz NI, Genant HK. Radiology. 1988 Nov; 169(2):517-24.

MRI

Can also show revascularization.

Objective evidence of tissue changes in response to treatment, allowing sequential evaluation on follow-up.

Understanding and treating osteonecrosis of the femoral head.Mont MA, Jones LC, Sotereanos DG, Amstutz HC, Hungerford DS. Instr Course Lect. 2000; 49():169-85.

T1 weighted image:

Subchondral changes in antero-superior quadrant of head with single line density, demarcating normal from ischemic bone.

T2 weighted image:

High signal line inside a low signal line (double-line sign.)

CT SCAN

Useful only in separating late pre-collapse stage from early collapse

Steinberg ME. Diagnostic imaging and role of stage and lesion size in determining outcome in osteonecrosis of the femoral head. Tech Orthop. 2001;16:6–15

BONE SCAN

Technetium 99m diphosphonate imaging is also a useful technique.

Khanuja HS, Mont MA, Etienne G, Hungerford DS. Treatment algorithm for osteonecrosis of the hip. Techn Orthop. 2001;16:80–9

STAGING

Arlet and Ficat in 1960’s described a 3 part staging system. Later a 4th stage was added in 1970’s.

Paul Ficat1917-1986

Disadvantages:Relies solely on plain radiographs, which are unrevealing early on.No measurement of lesion size or articular surface involvement.

Steinberg ME, Hayken GD, Steinberg DR. A quantitative system for staging avascular necrosis. J Bone Joint Surg Br. 1995;77[1]:34-41.)

Sugano et al. The 2001 revised criteria for diagnosis, classification, and staging of idiopathic osteonecrosis of the femoral head. Journal of Orthopaedic Science. September 2002, Volume 7, Issue 5, pp 601-605.

DIAGNOSTIC ALGORITHM

TRANSIENT OSTEOPOROSIS OF HIP (TOH)

No findings of bone infarction or repair, which are the

hallmarks of osteonecrosis.

The pathologic picture is primarily one of marrow edema,

hence also referred to as Bone marrow edema syndrome

(BMES) .

Clinically, pain is usually more sudden, severe.

In females, esp.during 3rd trimester of pregnancy

Dx can be made readily based on MRI in most cases.

TOH is usually self-limiting. Rx is protected weight bearing to

prevent #.

A diffuse low signal intensity in the T1-weighted image and a high intensity in the T2-weighted image

TREATMENT

AIMS:

Preserve rather than Replacing Femoral Head & Cartilage.

Early Intervention has favorable impact on the disease prognosis irrespective of the treatment modality used.

NON OPERATIVE TREATMENT

RESTRICTED WEIGHT BEARING:

Very few studies.

Cane or crutch ambulation.

Small pre-collapse lesions: Take longer to become symptomatic Rarely may resolve spontaneously.

A meta-analysis of RWB as a Rx modality; 21 studies in 819 hips:

Only 22.7% were satisfactory clinically 67% required hip arthroplasty or a salvage

procedure.

Now universally agreed, it is not an appropriate treatment modality

Review Core decompression versus nonoperative management for osteonecrosis of the hip.Mont MA, Carbone JJ, Fairbank AC, Clin Orthop Relat Res. 1996 Mar; (324):169-78.

LIPID LOWERING AGENTS

Prithcett in a clinical study reported that, at a mean of 7.5 yrs, only 1% of 284 patients taking corticosteroids along with STATINS developed AVN of femoral head in contrast to a prevalence of 3-20% in patients taking steroids alone.

Statin therapy decreases the risk of osteonecrosis in patients receiving steroids. Pritchett JW. Clin Orthop Relat Res. 2001 May; (386):173-8.

Glueck et al reported the use of Anabolic steroid Stanozolol (6mg/day) in patients who had hypofibrinolysis associated with a high level plasminogen activator activity. All patients showed a decrease of symptoms at one year following treatment.

Idiopathic osteonecrosis, hypofibrinolysis, high plasminogen activator inhibitor, high lipoprotein(a), and therapy with Stanozolol.Glueck CJ, Freiberg R, Glueck HI, Tracy T, Stroop D, Wang Y. Am J Hematol. 1995 Apr; 48(4):213-20.

Meizer et al studied the use of prostacyclin derivative Iloprost, in patients with osteonecrosis of femoral head and bone marrow edema syndrome. Among 17 patients with early stage AVN, all had clinical and radiographic improvement at one year.

MRI-controlled analysis of 104 patients with painful bone marrow edema in different joint localizations treated with the prostacyclin analogue iloprost. Meizer R et al. Wien Klin Wochenschr. 2005 Apr; 117(7-8):278-86.

Glueck et al used enoxaparin (60mg/day, 12 weeks) to treat patients of thrombophilic or hypofibrinolytic disorders and early stages of AVN. AT 2 yrs, 89% had not required surgery and were still in Ficat stage 1 or 2. They suggested that Rx of the underlying coag. Disorder may arrest or delay progression of AVN if started early.

Enoxaparin prevents progression of stages I and II osteonecrosis of the hip.Glueck CJ, Freiberg RA, Sieve L, Wang P. Clin Orthop Relat Res. 2005 Jun; (435):164-70.

Lai et al, in a study of patients with Steinberg Stage 2 or 3 osteonecrosis of the femoral head who were either treated with alendronate (70mg/day for 25 weeks) or assigned to a control group. At a minimum of 2 year follow up:

Only 2 of 29 hips in alendronate group had loss of femoral head integrity compared with 19 of 25 hips in control group (p<0.001)

1 hip in alendronate group and 16 hips in control group underwent THR.

However doses required and duration of treatment are yet to be clearly defined.

Also long term effect of these drugs, many of which have extremely long half lives, on normal bone homeostasis and turnover also merits caution.

The use of alendronate to prevent early collapse of the femoral head in patients with nontraumatic osteonecrosis. A randomized clinical study. Lai KA, Shen WJ, Yang CY, Shao CJ, Hsu JT, Lin RM. J Bone Joint Surg Am. 2005 Oct; 87(10):2155-9.

EXTERNAL, BIOPHYSICAL, NON OPERATIVE MODALITIES PULSED ELECTROMAGNETIC FIELD STIMULATION

Two fundamental mechanisms of action:

1. Important role in control of local inflammmation.

2. These favor repair activity and can potentiate the healing process by stimulating neo-vascularization and new bone formation.

Biophysical stimulation with pulsed electromagnetic fields in osteonecrosis of the femoral head.Massari L, Fini M, Cadossi R, Setti S, Traina GC. J Bone Joint Surg Am. 2006 Nov; 88 Suppl 3():56-60.

Radiographic progression in Ficat stage II . Hips treated with core decompression (CD) plus pulsed electromagnet fields (PEMF) exhibit 33% less radiographic progression than hips treated with CD alone (P 0.04)

EXTRACORPOREAL SHOCKWAVE THERAPY

Wang et al compared the results of ESWT with non vascularized fibular grafting in 23 patients.

At a mean of 25 months, 79% of the ESWT recipients had improved HHS as compared to only 29% of those with non-vascularised fibular grafting

Treatment for osteonecrosis of the femoral head: comparison of extracorporeal shock waves with core decompression and bone-grafting. Wang CJ, Wang FS, Huang CC, Yang KD, Weng LH, Huang HY. J Bone Joint Surg Am. 2005 Nov; 87(11):2380-7.

HYPERBARIC OXYGEN (HBO)

Improves oxygenation Reduces edema Induces angioneogenesis Thus reducing intraosseus pressure and

improving microcirculation

Reis et al, reported the use of HBO in 12 patients (16 hips) with Steinberg stage 1 disease. Each patient was given 100% oxygen via a mask at 2-2.4 atmospheres for 90 minutes for 100 consecutive days.

They reported that 13 of the 16 femoral heads subsequently appeared normal on MRI after this treatment.

Hyperbaric oxygen therapy as a treatment for stage-I avascular necrosis of the femoral head. Reis ND, Schwartz O, Militianu D, Ramon Y, Levin D, Norman D, Melamed Y, Shupak A, Goldsher D, Zinman C. J Bone Joint Surg Br. 2003 Apr; 85(3):371-5.

§ Core Decompression

§ Various Nonvascularized & Vascularized Bone Grafting Procedures

§ Osteotomy Procedures

§ Total Hip Arthroplasty

§ Hip Resurfacing Procedures

CORE DECOMPRESSION

Based on the concept that increased intramedullary pressure is involved in the pathogenesis of AVN.

Wang et al have shown short term effect of increased femoral head blood flow due to core decompression in the rabbit model.

Core decompression is expected to relieve pain & to allow creeping substitution to the necrotic area by bringing the blood supply through th drill channel.

The effect of core decompression on femoral head blood flow in steroid-induced avascular necrosis of the femoral head. Wang GJ, Dughman SS, Reger SI, Stamp WG. J Bone Joint Surg Am. 1985 Jan; 67(1):121-4.

A meta-analysis of 24 reports analyzing 1206 hips treated with or without cancellous bone grafting revealed an overall clinical success rate of 63.5%. Less than 33% of the hips required a replacement or salvage procedure during the follow-up period.

Core decompression versus nonoperative management for osteonecrosis of the hip.Mont MA, Carbone JJ, Fairbank AC. Clin Orthop Relat Res. 1996 Mar; (324):169-78.

Conventional method involves the use of an 8-10mm trephine or cannula inserted under flouroscopic guidance to penetrate the lesion.

Kim et al compared the efficacy of two drilling methods (multiple drillings vs conventional core decompression)in treatment of pre collapse osteonecrosis in 54 patients.

The average pre and post operative HHS were comparable

The group that had undergone multiple drillings (3mm drill bits) had significantly longer time before collapse (42.3 m vs 22.6m)

Lower rates of collapse within 3 yrs after operation (55% vs 85.7%)

Kim SY, Kim DH, Park IH. Multiple drilling compared with core decompression for the treatment of osteonecrosis of the femoral head. J Bone Joint Surg Br. 2004;86:149

Currently recommended for the treatment of Ficat stage 1 or 2A, small central lesions in young, non-obese patients who are not taking steroids.

Campbell’s Operative Orthopedics. 12th Edition

USE OF OSTEOINDUCTIVE SUBSTANCES ALONG WITH CORE DECOMPRESSION

Bone Morphogenic Proteins:

Lieberman et al suggested that core decompression may be more effective if combined with BMP and/or angiogenic fators.

Treatment of osteonecrosis of the femoral head with core decompression and human bone morphogenetic protein. Lieberman JR, Conduah A, Urist MR. Clin Orthop Relat Res. 2004 Dec; (429):139-45.

Bone marrow mesenchymal cell grafting:

Mesenchymal stem cells (MSC) from adult bone marrow are multipotent that can diff. into fibroblastic, osteogenic, myogenic, adipogenic and reticular cells.

Osteonecrosis is associated with a decrease in progenitor cells in the proximal femur.

MRI has shown that conversion of red to fatty marrow occurs prematurely in some patients with AVN.

Fatty marrow conversion of the proximal femoral metaphysis in osteonecrotic hips. Koo KH, Dussault RG, Kaplan PA, Ahn IO, Kim R, Devine MJ, Cui Q, Cho SH, Wang GJ. Clin Orthop Relat Res. 1999 Apr; (361):159-67.

As a consequence intramedullary vascularity is altered and may be a predisposing factor to AVN.

Lack of osteogenic cells also can influence bone repair which occurs after osteonecrosis.

The current guidelines are that these should be instilled in a conc. of 2X106 stem cells in non-traumatic precollapse stage of AVN.

The use of percutaneous autologous bone marrow transplantation in nonunion and avascular necrosis of bone. Hernigou P, Poignard A, Manicom O, Mathieu G, Rouard H. J Bone Joint Surg Br. 2005 Jul; 87(7):896-902

Various studies e.g. Gangji et al (2005), Yan et al (2006), Deltro et al (2008) have concluded that percutaneous decompression augmented by MSC implantation is safe and more efficacious than decompression alone.

Treatment of osteonecrosis of the femoral head with implantation of autologous bone-marrow cells. Surgical technique. Gangji V, Hauzeur JP. J Bone Joint Surg Am. 2005 Mar; 87 Suppl 1(Pt 1):106-12.

Treatment of osteonecrosis of the femoral head by percutaneous decompression and autologous bone marrow mononuclear cell infusion. Yan ZQ, Chen YS, Li WJ, Yang Y, Huo JZ, Chen ZR, Shi JH, Ge JB. Chin J Traumatol. 2006 Feb; 9(1):3-7

Daltro GC, Fortuna VA, Salvino de Araújo SA, FerrazLessa PI, Sobrinho UA, Borojevic R. Femoral head necrosis treatment with autologous stem cells in sickle cell disease. Acta Orthop Bras. 2008;16:44–8.

BONE GRAFTING Bone grafting procedures are a group of joint

preserving techniques that involve the removal of the diseased femoral head segment, followed by its replacement with 1 or more of a variety of bone graft options.

These are most valuable in treating patients with Stage I & II disease

TECHNIQUES OF BONE GRAFTING

Grafting through lateral core track

Grafting through femoral neck window

Grafting through articular surface window

GRAFTING THROUGH LATERAL CORE TRACK

Advantages:-

Simple technique Minimal Invasiveness Avoidance of surgical dislocation of the hip Low Complication Rate Can be performed bilaterally under one anesthetic

Disadvantages:-

Inability to directly visualize the joint surfaces Inexact nature of removing diseased bone & replacing it with bone graft under fluoroscopic guidance Risk of postoperative #

LIGHT BULB PROCEDUREA window is created to expose the anterior femoral neck, at the level of the junction of the femoral head & neck

When Combined with a Bone Grafting procedure, referred to as the “light bulb” procedure. Advantage is the improved access to the necrotic femoral head segment & the avoidance of direct iatrogenic cartilage damage

Disadvantage is the creation of a cortical defect in the femoral neck, which raises the risk of fracture

TRAPDOOR PROCEDURE The 3rd method of accessing the necrotic segment of the femoral head is

known as the “Trapdoor” approach

With this method, the hip is surgically dislocated using a technique aimed at preserving the blood supply to the femoral head & neck

Once exposed, a “trapdoor” window is made in the femoral head cartilage to access the diseased subchondral bone

When combined with a bone grafting procedure, referred as the “Trapdoor” Procedure

Advantage : Exposure allows a direct evaluation of the cartilage surface &

underlying diseased femoral head segment & allows for

precise bone graft placement.

Disadvantage : Demanding technical nature

Iatrogenic cartilage damage & osteonecrosis

Surgical dislocation

Trapdoor

Lightbulb

Most authors recommend non-vascularised bone grafts for hips with less than 2mm of femoral head depression or those in which core decompression has failed and there is no acetabular involvement (Ficat stage 1 and 2)

Campbell’s Operative Orthopedics. 12th edition

Nonvascularized cortical bone grafts are typically prepared as several struts that provide structural support under the articular surface within the evacuated segment

This construct is often augmented with cancellous bone graft in an effort to improve its osteoconductive and/or osteoinductive properties

Local pedicled grafts ,which do not require microvascular reanastomosis.

eg :Muscle-pedicle bone grafts

Free vascularized grafts, which require a microvascular reanastomosis. eg: Free vascularized fibula graft

Nonvascularized Grafts Vascularized Grafts

MUSCLE-PEDICLE BONE GRAFT

FREE VASCULARISED FIBULAR GRAFTING

POROUS TANTALUM ROD INSERTION

A novel approach in the treatment of stage I & II precollapse osteonecrosis

This rod functions analogously to a Cortical Strut Graft allowing structural & osteoconductive properties

OSTEOTOMIES

The main biomechanical effect is to rotate the necrotic or collapsing segment of the hip out of the weight bearing zone, replacing it with a segment of articular cartillage of the femoral head supported by healthy viable bone.

Additionally, may also reduce venous hypertension and decrease intramedullary pressure.

TYPES OF OSTEOTOMIES

2 main types have been described:

Trans-trochanteric rotational osteotomy

Intertrochanteric varus or valgus osteotomy(usually combined with either flexion or extension)

IDEAL PATIENT FOR OSTEOTOMY

Not being treated with long term steroids

Minimal osteoarthritic changes, with no loss of joint space or acetabular involvement

Small combined necrotic angle

Disadvantages:

Technically demanding

Subsequent conversion to THR may be difficult

 Shannon BD, Trousdale RT. Femoral osteotomies for avascular necrosis of the femoral head. Clin Orthop Relat Res. 2004;418: 34-40

VALGUS OSTEOTOMY WITH FLEXION AND BONE GRAFTING

VARUS OSTETOMY

ROTATIONAL OSTEOTOMY

HIP RESURFACING

THR has a higher rate of failure in this cohort.

May be because of the relative youth of these patients and lack of other factors limiting physical activity.

Accordingly, temporizing procedures have evolved which include:

Resurfacing Hemi-arthroplasty Total resurfacing arthroplasty

Resurfacing procedures have demonstrated clinical promise

but current short- and long-term results for resurfacing procedures remain variable

Schmalzried TP. Total resurfacing for osteonecrosis of the hip. Clin Orthop Relat Res. 2004;429:151-156.Adili A, Trousdale RT. Femoral head resurfacing for the treatment of osteonecrosis in the young patient. Clin Orthop Relat Res. 2003;417:93-101.Grecula MJ. Resurfacing arthroplasty in osteonecrosis of the hip. Orthop Clin North Am. 2005;36(2):231-242.

TOTAL HIP ARTHROPLASTY

TOC for advanced osteonecrosis of the hip (University of Pennsylvania Stages IVB–VIC)

Excellent pain relief & functional

improvements

More recent studies at intermediate follow up up to 10 years have demonstrated similar survivorship compared to total hip replacement for osteoarthrosis.

Kim YH, Oh SH, Kim JS, et al. Contemporary total hip arthroplasty with and without cement in patients with osteonecrosis of the femoral head. J Bone Joint Surg Am. 2003;85-A(4):675-681.

Operated at Ortho Unit-IBone & Joint Surgery Hospital•Name: Shareef Ahmad•Dx: Idiopathic AVN•Rx: Non-cemented total hip arthroplasty

Thank you