A NEW CLASSIFICATION FOR HETEROTOPIC OSSIFICATIONS IN TOTAL HIP-ARTHROPLASTY CONSIDERING THE SURGICAL APPROACH

We would like to introduce a new classification for heterotopic ossifi cations (HO) after total hip arthroplasty which also considers ossific ations within the region of the surgical approach. Furthermore, we wil l point out the influence of the surgical approach on the rate of HO. We analyzed 75 cementless hip arthroplasties with consecutive HO in a prospective study. The operations were performed by three experienced orthopaedic surgeons using an identical stem and a standardized latera l approach. All patients followed an identical rehabilitation procedur e, Clinical and radiological data were documented in a standardized wa y. We found a total of 40 HO. Only 24 could be exactly classified by t he known methods. Our classification considers 3 regions and 4 grades and is relevant for all 40 HO. Electrocauterisation to dissect the mus cles in the lateral approach reduced the rate of HO: overall 64.3% to 39.4%; clinically relevant ossifications were reduced to 3.0% from 16. 7%. Our new classification considers all HO concerned with total hip a rthroplasty, especially those localized in the intertrochanteric regio n. The rate of HO can be reduced by using electrocauterisation for mus cle dissection in the lateral approach.