J Korean Orthop Assoc.  2012 Feb;47(1):35-40. 10.4055/jkoa.2012.47.1.35.

Early Aseptic Loosening after Total Knee Replacement Using Legacy Posterior Stabilized-Flex Prosthesis

• Choi YJ
• Kang JH
• Lee KW
• Joo YS
• Park JS
• Choo HH

• KMID: 1439990
• DOI: http://doi.org/10.4055/jkoa.2012.47.1.35

Abstract

PURPOSE
We analyzed the patterns and causative factors of early aseptic loosening after total knee arthroplasty (TKR) using a legacy posterior stabilized (LPS)-flex prosthesis.
MATERIALS AND METHODS
We examined 483 cases that occurred in 311 patients who underwent TKR using LPS-flex by single surgeon between August 2001 and March 2007 and who were followed-up for at least 2 years. The loosened group included 25 cases that exhibited early aseptic loosening on radiograph, the remaining 458 cases were regarded as the control group, and analysis was performed.
RESULTS
The mean loosening period was 34.7 months and femoral component loosening alone was found in 22 cases (88%). There were no statistically significant differences in age, body mass index, or pre-operative range of motion between the 2 groups, but varus deformity was more severe in the loosened group (mean 8.92degrees) than in the control group (mean 5.21degrees) (p=0.003). Protrusion of the femoral component proximally over posterior condyle of the distal femur were more prominent in the loosened group (mean 20.3%) than in the control group (mean 13.4%) (p=0.001).
CONCLUSION
Early loosening after TKR using LPS-flex prosthesis developed mostly in the femoral component. Choosing a proper size for the femoral component and cutting level for the distal femur should be considered.

Keyword

femoral prosthesis; loosening; arthroplasty replacement total

MeSH Terms

Arthroplasty
Arthroplasty, Replacement, Knee
Body Mass Index
Congenital Abnormalities
Femur
Humans
Knee
Prostheses and Implants
Range of Motion, Articular

Figure

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  Figure 1 We measured the extent of protruded femoral component by the proportion of uncovered surface (A) to total length of posterior condyle of femoral component (B).

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  Figure 2 A 65-year-old female patient (A-D) had lateral radiographs taken at 13, 60, 77, and 84 months respectively, showing progressive loosening at anterior flange and posterior condyle with proximal migration of femoral component. (E) There was a scanty cement mantle on backside of the femoral component.

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