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Fig. 3 | BMC Musculoskeletal Disorders

Fig. 3

From: Influence of extension stem length and diameter on clinical and radiographic outcomes of revision total knee arthroplasty

Fig. 3

Example of CFR parameter evaluation. Left, the stem diameter is 1.04 cm, whereas the narrowest part of medullary canal which is occupied by the stem is 1.42 cm. CFRmax = 1.04/1.42 = 0.73. CFR > 0.85: negative. Right, for the calculation of CFR0.7 length, divide stem diameter (1.04 cm) by 0.7 equals to 1.49 cm. Measure the length from stem tip to the level where canal diameter is 1.49 cm. In this case, it is 1.15 cm. As a result, CFR0.7 > 2 cm: negative, CFR0.7 > 4 cm: negative, CFR0.85length: 0 cm, CFR0.7 length: 1.49 cm

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