Fragmentation of the Polyethylene Cement Restrictor in Total Hip Arthroplasty

The presence of polyethylene wear particles at the bone-cement interface after joint replacement is considered a major cause of prosthetic loosening.

Nevertheless, many surgeons continue to use winged Hardinge polyethylene restrictor of which fragments are frequently seen to detach during insertion into the femoral canal, and to emerge during medullary lavage. The extent to which such fragments may be retained in the femoral cement mantle is not clear, and there is obvious concern that such fragments may result in polyethylene granuloma formation. We reviewed 89 post-operative X-rays after hip replacement employing the Hardinge restrictor. The following issues were examined:

1. Dimensions and number of distal radiolucencies in the cement and their correspondence with the wing size of the restrictor,

2. method of suction used during pressurised lavage,

3. Proximal and distal canal diameter and amount of taper,

4. Gruen zone location of radiolucencies.

Linear lucencies corresponding exactly to the wings of the restrictor were found on 14 X-rays (15.7%), 7 were seen out of 54 cases in which distal suction was used during lavage, and 7 were seen in 35 cases in which proximal suction only was employed. There was no statistical difference between these two methods of suction in limiting the number of retained fragments of restrictor (P= 0.156).

There was no correlation between the likelihood of fragment detachment and canal taper or distal diameter. A total of (17) detached fragments were identified, distributed in the following Gruen zones; 3 (35.3%), 4 (38.2%), 5 (26.5%). We suggest that the above observations should alert surgeons who wish to use this type of restrictor to the importance of meticulous femoral preparation, preferably under direct vision, to ensure that no fragments of restrictor become detached