12. Sử dụng Steroid
Corticosteroids: Prednislone / Methyprednislone:
sử dụng trong điều trị hen suyễn
Bệnh lý da liễu
Các bệnh lý tự miễn
Ghép thận
Không có lựa chọn điều trị khác
trong những trường hợp trên
Liên quan tới Steroid thường xảy ra hai bên
(50-80%)
24. MRI
Phương pháp có giá trị nhất (ĐN: 97%, DDH: 98%)
PROTOCOL
COR T1 SE NON FAT SAT
COR FSE STIR
AXIAL T2 FSE FAT SAT
AXIAL OBLIQUE PD FSE FAT SAT
COR T2 FSE FAT SAT
SAG T2 FSE FAT SAT or SAG PD FAT SAT
32. MRI SÀNG LỌC NHANH
• MRI thường quy để phát hiện sớm AVN ở
những bệnh nhân có yếu tố nguy cơ nhưng
không triệu chứng.
• Rapidly acquired MRI thời gian <1 phút, phát
hiện 92% TH (SEN: 99%, SPE: 98%)
• Có thể dùng chụp toàn thân
The rapidly acquired MR sequences (<1 min) that we studied reliably revealed
the presence or absence of AVN, marrow edema, and osteoarthritis of the hip
in our sample population when compared with SE and TSE sequences that we
routinely perform (>7 mins) (May DA et al.)
- NORMAL MARROW is devided into red marrow and yellow marrow
- Conversion to yellow marrow in apo-/epiphysis of the femur in 1st year
FEEDING VESSELS
Three vessels feed the femoral head:
1. Medial femoral circumflex artery
2. Lateral femoral circumflex artery
3. Artery of Ligamentum Teres
The Medial is considered the most important
Avascular Necrosis is condition in which there is loss of blood supply to the bone.
bone death
If bone death progresses leads to bone collapse
Blood supply to femoral Head (ball of hip joint) is interrupted by
Traumatic
Nontraumatic
Femoral head: Death of bone cells and marrow
Dead segment of bone
Further collapses and loss of sphericity
CAUSES
Traumatic: Fracture in neck of Femur, dislocations of hip
Nontrauamtic: Steroid use, Excess Alcohol intake, Other blood cell disorders, Deep sea divers and miners
Dysbaric osteonecrosis
Caisson disease / Aeroembolism.
Seen in deep sea divers , tunnel workers, working under more than 30m
Nitrogen gas bubbles liberated in a concentration that cannot be readily absorbed by blood stream or excreted by lungs.
As a result gas bubbles accumulate in tissues causing local ischemia or intravascular occlusion
TRAUMA
STEROID INDUCED
Corticosteroids: Prednislone / Methyprednislone: used in management of Asthma
Skin diseases
Immunological diseases
Renal transplant
In the above conditions there is no choice
Steroid induced is usually Bilateral (50-80%)
CLINICAL FEATURES
AGE: 3rd-5th decade
Very rare in extremes of age
Mean age is 5th decade
Male/Female = 4/1
COMPLAINTS
Pain:groin,buttocks, Front of thigh
Limp
Stiffness in hip
Night pain
Clinical symptoms are
Poor
Non specific
Asymptomatic in early stage
Imaging
Imaging tools
4 zones in AVN
A-ARTICULAR CARTILAGE
B-ZONE OF ISCHAMIA
C–REPARATIVE ZONE
D-NORMAL BONE
1.Early stages of AVN : X ray not useful even though there is pain
2.Advanced Stages of AVN :
Bone cyst
Crescent sign
collapse of dead bone
arthritic changes
Bone cyst + sclerosis
Subchondral osteoporotic fracture -Crescent sign
Collapse
Flattening of headJoint space narrowing + Osteoarthotic changes
MRI = 2nd step
For diagnosing
Quantifying
Staging
Evaluating respond to treatment
Follow-up
The most sensitive modality (SEN: 97%, SPE: 98%)
T1
- Hypointense peripheral band = reactive interface
- +/- Hypointense bone marrow edema
- +/- Hypointense joint effusion
T2
- Characteristic “double line” sign in 80%
T1 C+
Early stage – decreased enhancement
Nonviable trabeculae + marrow – no enhancement
Enhancement corresponds to reparative zone
Type A
Several MRI sequences of avascular necrosis of the femoral head. Reparative granulation tissue, which strongly enhances, is seen around the periphery of the necrosis.
Type C
FICAT AND ARLET STAGING
Stage 0
Normal Imaging
Stage 1
Positive bone scan/MR
Stage 2
Mottled femoral head/ Sclerosis/cyst/osteopenia
Stage 3
Crescent sign lesions + depression femoral head
Stage 4
Flattening articular surface
Joint space narrowing
Secondary acetabular changes
The disadvantage of MRI is its limited differentiation between Stages II and III avascular necrosis of the femoral head
Rapidly acquired MRI IN SCREENING AVN
Regular MRI used for screening patients having risks but no symptom.
Rapidly acquired MRI (less than 1min) is used to detect AVN (92% cases)
Can be used for whole-body scan
Scintigraphy
A very sensitive investigation
Scan shows cold spot at places of AVN
Replaced now by MRI
TREATMENT
Once AVN started : treatment depends on Stage of Disease and symptoms/Age/general health of patient
AVN is irreversible: no drugs can restore blood supply to femoral head
Keeping weight of affected hip = Crutch walking
Anti inflammatory medications
Bisphosphnates :Reduces risk of femoral head collapse
Blood thinning drugs with a hope of maintaining precarious blood supply
SURGERY
Early stage
No Collapse operations to increase blood supply
Core Decompression with or with out bone graft
Advanced stage
Arthritic Hip
Total Hip Replacement
DECOMPRESSION OF FEMORAL HEAD + VASCULARISED FIBULAR GRAFT
1. Decompression of femoral head is done by making a hole into femoral head.
2. A fibular graft along with its blood vessels is removed from the leg and inserts into the hole created in femoral neck and head. Surgeon then connects the blood vessels of the fibula to the blood vessels around the hip.
3. It can help to restore the blood supply .
Fibular graft act as strut and help in preventing collapse of femoral head
POSTOPERATIVE MANAGEMENT
After decompression it weakens the femoral neck & head
Protected weight bearing with aid of crutches and walker for 6 weeks
Weight bearing after 6 weeks and return to regular activities.
