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Friday, March 2, 2001

Late dislocation after THA is found more common

Late dislocation after total hip arthroplasty (THA) is more common than previously thought. About one quarter (27 percent) of dislocations occurred for the first time after more than five years, say investigators who followed 25,465 primary total hip arthroplasties performed at a single institution between 1969 and 1995.

Their report in scientific paper 73 on Thursday defined late dislocation as cases in which the first dislocation occurred more than five years after operation. Results: 616 of 25,465 hips (2.4 percent) dislocated: 451 (1.8 percent) before five years and 165 (0.6 percent) at five years or more. The median time to dislocation in the late dislocation group was 11.3 years (range: 5.0 to 24.9).

Compared to early dislocation, late dislocation was more frequent in women (p = 0.02), but did not correlate with age at THA. Factors associated with late dislocation included previous subluxations in 20, trauma in 11 and onset of neurologic impairment in 11. Late dislocation occurred in association with polyethylene wear > 2 mm in 18, implant change in eight, and acetabular malposition in 30.

The late dislocation become recurrent in 90 (55 percent) and required reoperation in 55 (30 percent). The likelihood of late dislocation becoming recurrent is high say the investigators, Marius von Knoch, MD, Hamburg, Germany; and Daniel J. Berry, MD, and Bernard F. Morrey, MD, both of Mayo Clinic, Rochester, Minn.

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2001 Academy News March 2 Index C

Last modified 15/February/2001 by IS