- See:
-
Types of Loosening:
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Exam for THR Loosening:
- Grading of Cement Technique: (Barrack et. al. JBJS 1992 and Mulroy et.al. 1995)
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Grade A: meduallary canal completely filled w/ cement (white out).
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Grade B: a slight radiolucency exists at the bone cement interface.
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Grade C: a radiolucency of more than 50% at the bone cement interface.
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Grade D: a radiolucency involving more than 100% of the interface between bone and
cement in any projection, including absence of cement distal to the stem tip;
- as noted by Mulroy et.al. 1995, a femoral cement mantle less than 1 mm and
defects in the cement mantle are associated with early loosening;
- Radiographic Stem Loosening:
- note that radiolucent lines are commonly found in the lateral and anterior aspects of the proximal
femur, since these areas can be difficult to visualize and difficult to pressurize;
- in the proximal 1 cm of the femur, linear radiolucencies less than 2 mm
in width should not be considered to be indicative of loosening;
-
definite loosening:
-
stem fracture
-
cement fracture;
- cement-prosthesis lucency: radiolucency at the cement component interface greater than 1 mm in width;
- is a definite sign of loosening if a new radiolucent line of any size apprears at the cement
prosthesis interface which
was not present on initial postoperative radiographs;
- cement debonding between the prosthesis and the cement in zone 1 (anterolateral segment), may not necessarily
correlate with poor clinical results;
-
changes in stem position:
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pistoning:
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medial midstem pivot:
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calcar pivot:
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subsidence;
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distal pivot:
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probable loosening:
-
radiolucent lines: continuous radiolucency at bone cement interface;
- typically these radiolucent lines will be surrounded by lines of increased density;
- endosteal cavitation (linear osteolysis and focal osteolysis) are also suggestive of femoral loosening;
-
possible loosening:
-
radiolucent lines at cement bone interface from 50-100% of the total bone cement interface;
- Technical Failures Causing Loosening:
- as noted by Kobayashi et al 1997., a "stove pipe" femur is a strong risk factor for radiographic loosening in cemented femoral components;
- Assessment of cement column:
Factors affecting aseptic failure of fixation after primary Charnley Total Hip Arthroplasty.
S. Kobayashi et al. JBJS. Vol 79-A. No 11. Nov 1997. p 1618.
Short-term aseptic loosening of the femoral component in canine total hip replacement: effects of cementing technique on cement mantle grade.
Comparison between triple-tapered and double-tapered cemented femoral stems in total hip arthroplasty: a prospective study comparing the C-Stem versus the Exeter Universal early results after 5 years of clinical experience.
Femoral component loosening using contemporary techniques of femoral cement fixation.
