Three Key Reporting Criteria
Orthopedic management depends on all three:
- Fracture location — trochanteric, along femoral stem, or well distal to stem
- Prosthesis stability — stable vs. loose (present in ~70% of periprosthetic fractures)
- Bone stock quality — good vs. poor (determines revision hardware options)
Medial Buttress
The medial cortex along the proximal femoral stem is a key landmark. Fractures that disrupt the medial buttress may compromise femoral stem stability regardless of where the fracture line originates — note any medial cortex involvement explicitly.
Prosthesis Stability Assessment
| Finding | Press-Fit (Uncemented) | Cemented |
|---|---|---|
| Fixation surface disruption (traumatic loosening) | Fracture extending along textured proximal ingrowth surface — shears off osseointegration | Fracture paralleling or disrupting cement mantle |
| Periprosthetic lucency (preexisting loosening) | Lucency >2 mm at bone-prosthesis interface (especially divergent/widening); radiolucency around proximal textured surface — abnormal; lucency around distal smooth surface — may be normal (<2 mm) | Continuous radiolucency around entire cement mantle — abnormal; lucency >2 mm at bone-cement interface; any lucency not present on initial postop XR |
| Progressive lucency | Any progression after 2 years postop | Any progression after 2 years postop |
| Subsidence / migration (>5 mm or >2 yrs postop = abnormal) | Caudal settling of stem relative to femur. Measure: greater trochanter → lateral shoulder of prosthesis; OR lesser trochanter (most medial point) → medial shoulder of prosthesis. Also assess tilting (varus/valgus) and rotation | Same measurement approach |
| Other signs | Bony pedestal at prosthesis tip; bead shedding; endosteal scalloping; osteolysis | Cement fracture; prosthesis fracture; eccentric femoral head position (liner wear → particle disease) |
| Prosthesis fracture | Diagnostic of instability regardless of other findings | Diagnostic of instability regardless of other findings |
Normal Findings — Do Not Overcall Loosening
Press-fit (uncemented): thin radiolucent line <2 mm around distal (smooth) stem; trabecular ingrowth / spot welds at textured surface; stress shielding (proximal bone resorption + distal cortical hypertrophy); subtle pedestal sclerosis in first 2 years postop.
Cemented: small air bubbles in cement; radiolucent line <2 mm at bone-cement interface (stable, nonprogressive); thin cement mantle surrounding stem.
Stress Riser
When a plate does not overlap the distal stem tip, the unprotected bone segment between two implants concentrates stress, increasing interprosthetic fracture risk. Cortical plates should extend distally past the stem tip.
Reporting Checklist
- General fracture description: displacement, comminution, angulation, alignment
- Fracture location: greater trochanter / lesser trochanter / along or just distal to femoral stem / well distal to stem (≥4–5 cm from tip)
- Implant stability — signs of loosening:
- Fracture extension to or along fixation surface (textured ingrowth or cement mantle)
- Periprosthetic osteolysis / lucency (>2 mm; progressive; divergent)
- Subsidence, tilting, or rotation vs. prior imaging
- Prosthesis or cement fracture
- Bone stock: presence and severity of bone loss (cortical thinning, medullary widening, cancellous loss, osteopenia, comminution)
- Bone loss location: trochanteric / proximal stem / entire stem / extensive with distortion
- Imaging recommendation: CT if radiographs are equivocal and patient cannot bear weight, or for surgical planning (note: metallic streak artifact may limit CT)
Reference
Marshall RA et al. Periprosthetic Femoral Fractures in the Emergency Department: What the Orthopedic Surgeon Wants to Know. RadioGraphics. 2017;37(4).