, Paul D. Siney1 and Patricia A. Fleming1
(1)
The John Charnley Research Institute Wrightington Hospital, Wigan, Lancashire, UK
The study by Griffith et al. [1] has established the method of wear measurement of the UHMWPE on serial radiographs. It was essential that the results of the method were validated by comparison with measurements taken directly from explanted cups.
The Study
Acrylic casts (Fig. 32.1) and the shadowgraph technique (Fig. 32.2) were used to compare the real penetration of the cup with measurements taken from pre-revision radiographs. Twenty two paired observations were compared [2].
Fig. 32.1
Acrylic cast used to measure the real penetration of the cup
Fig. 32.2
Shadowgraph technique used to measure the penetration of the cup (Reproduced with permission and copyright © of the British Editorial Society of Bone and Joint Surgery from Wroblewski [2])
The mean real (shadowgraph) penetration rate was 0.19 mm/year (0.017–0.52 mm/year) compared with 0.21 mm/year (0–0.41 mm/year) as measured on radiographs (Fig. 32.3).
