Degenerative Joint Disease (DJD)
Macroscopic & Microscopic Appearance of Normal vs. Damaged Articular Hyaline Cartilage by DJD
Hip Osteoarthritis (OA) aka Osteoarthrosis
- Symptomatic and potentially disabling DJD
- Progressive damage and loss of the articular cartilage causing denudation and eburnation of articular bone
- Cystic changes, osteophytes and gradual joint destruction
- Develops d/t repeated joint loading and microtrama
- Obesity, metabolic/genetic factors
- Secondary Causes: trauma, FAI syndrome, osteonecrosis, pyrophosphate crystal depostion, previous inflammatory arthritis, Slipped Capital Femoral Epiphysis, Leg-Calves-Perthes disease in children etc.
- Hip OA, 2nd m/c after knee OA. Women>men
- 88-100 symptomatic cases per 100000
Radiography is the Modality of Choice for the Dx and Grading of DJD
- Special imaging is not required unless other complicating factors exist
- Acetabular-femoral joint is divided into superior, axial and medial compartments/spaces
- Normal joint space at the superior compartment should be 3-4-mm on the AP hip/pelvis view
- Understanding the pattern of hip joint narrowing/migration helps with the DDx of DJD vs. Inflammatory arthritis
- In DJD, m/c hip narrowing is superior-lateral (non-uniform) vs. inflammatory axial (uniform)
AP Hip Radiograph Demonstrates DJD
- With
non-uniform loss of joint space (superior migration), large subcortical cysts and subchondral sclerosis - Radiographic features:
- Like with any DJD changes: radiography will reveal L.O.S.S.
- L: loss of joint space (non-uniform or asymmetrical)
- O: osteophytes aka bony proliferation/spurs
- S: Subchondral sclerosis/thickening
- S: Subcortical aka subchondral cysts “geodes”
- Hip migration is m/c superior resulting in a “tilt deformity”
Radiographic Presentation of Hip OA May Vary Depending On Severity
- Mild OA: mild reduction of joint space often w/o marked osteophytes and cystic changes
- During further changes, collar osteophytes may affect femoral head-neck junction with more significant jint space loss and subchondral bone sclerosis (eburnation)
- Cyst formation will often occur along the acetabular and femoral head subarticular/subchondral bone “geodes” and usually filled with joint fluid and some intra-articular gas
- Subchondral cysts may be occasionally very large and DDx from neoplasms or infection or other pahtology
Coronal Reconstructed CT Slices in Bone Window
- Note moderate joint narrowing that appears non-uniform
- Sub-chondral cysts formation (geodes) are noted along the acetabular and femoral head subchondral bone
- Other features include collar osteophytes along head-neck junction
- Dx: DJD of moderate intensity
- Referral to the Orthopedic surgeon will be helpful for this patient
AP Pelvis (below first image), AP Hip Spot (below second image) CT Coronal Slice
- Note multiple subchondral cysts, sever non-uniform joint narrowing (superior-lateral) and subchondral sclerosis with osteophytes
- Advanced hip arthrosis
Severe DJD, Left Hip
- When reading radiological reports pay particular attention to grading of hip OA
- Most severe (advanced) OA cases require total hip arthroplasty (THA)
- Refer your patients to the Orthopedic surgeon for a consultation
- Most mild cases are good candidate for conservative care
Hip Arthroplasty aka Hip Replacement
- Can be total or hemiarthroplasty
- THA can be metal on metal, metal on polythelen and ceramic on ceramic
- Hybrid acetabular component with polyethelen and metal backing is also used (above right image)
- THA can be cemented (above right image) and non-cemented (above left image)
- Non-cemented arthroplasty is used on younger patients utilizing porous metallic parts allowing good fusion and bone ingrowth into the prosthesis
Failed THA May Develop
- Most develop within
first year and require revision - Femoral stem may fracture (above left)
- Postsurgical infection (above right)
- Fracture adjacent to prosthesis (stress riser)
- Particle disease
Femoroacetabular Impingement Syndrome
- (FAI): abnormality of normal morphology of the hip leading to eventual cartilage damage and premature DJD
- Clinically: hip/groin pain aggravated by sitting (e.g. hip flexed & externally rotated). Activity related pain on axial loading esp. with hip flexion (e.g. walking uphill)
Pincer type acetabulum: > in middle age women potentially many causes- CAM-type deformity: > in men in 20-50 m/c 30s
- Mixed type (pincer-CAM) is most frequent
- Up until the 90s FAI was not well-recongnised
FAI Syndrome
- CAM-type FAI syndrome
- Radiography can be a reliable Dx tool
- X-radiography findings: osseous bump on the lateral aspect of femoral head-neck junction. Pistol-grip deformity. Loss of normal head sphericity. Associated features: os
acetabule , synovial herniation pit (Pit’s pit). Evidence of DJD in advanced cases - MRI and MR arthrography (most accurate Dx of labral tear) can aid the diagnosis of labral tear and other changes of FAI
- Referral to the Orthopedic surgeon is necessary to prevent DJD progression and repair labral abnormalities. Late Dx may lead to irreversible changes of DJD
AP Pelvis: B/L CAM-type FAI syndrome
Pincer-Type FAI with Acetabula Over-Coverage
- Key radiographic signs: “Cross-over sign” and abnormal center-edge and Alfa-angle evaluation methods
Dx of FAI
- Center-edge angle (above the first image) and Alfa-angle (above the second image)
- B/L CAM-type FAI with os acetabule (above right image)
MR Arthrography
- Labral tear and CAM-type FAI syndrome on axial (above left) and coronal T2 W (above right) MR arthrography
- Note acetabula labral tear. Referral to orthopedic surgeon is required. For more information:
- https://radiopaedia.org/articles/femoroacetabular-impingment-1
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