[Hip joint arthroplasty following surgical treatment of acetabular fracture]

A group of 49 patients treated by total hip arthroplasty after previous surgery for an acetabular fracture are evaluated in this retrospective study.

In the period from 1997 to 2004, 49 patients, 35 men and 14 women, with posttraumatic arthritis following acetabular fracture were treated in our department. The average age was 42 years, with 67 % of the patients being younger than 40 years. The average follow-up was 42 montsh (range, 18 to 92). The acetabular fractures evaluated by the AO classification included type A1 in 17 patients, type A2 in seven, type B1 in nine, type B2 in six, type B3 in seven, type C1 in three and type C2 in two patients.

In 11 patients with aseptic necrosis of the femoral head without acetabular deformity, cementless Zweymüller Bicon or Spotorno CLS acetabular components were used. Twenty-nine patients with acetabular defects of type I and II, according to the American Academy of Orthopedic Surgeons (AAOS) classification, underwent acetabular reconstruction with the bone impaction grafting technique, using allogenic grafts and cementless Zweymüller Bicon acetabular components. Four patients with AAOS type III acetabular defects were treated with impacted morsellized bone allografts, using titanium mesh and cemented polyethylene acetabular cups. Three patients were treated with solid bone grafts fixed with osteosynthetic material. In two patients with type IV defects, osteosynthesis using a plate completed with allogenic bone graft, a mesh and a cemented cup were used.

The patients were evaluated with the use of Harris hip scores. In 20 patients (43 %) the outcomes were excellent, and very good in 18 (37 %), satisfactory in six (12 %) and poor in four (8 %) patients.

Hip joint arthroplasty following the surgical treatment of acetabular fracture is indicated in patients with post-traumatic hip arthritis. This frequently occurs due to complications associated with surgery for acetabular fractures, or the cause remains unknown. Some types of these fractures show a high proportion of poor results. The group can be divided into two different subgroups: the patients with a spherical, healed acetabulum and the patients with acetabular deformity or defect, of which the most serious condition is pseudoarthrosis of one or both columns. In the first subgroup, the surgical technique of acetabulum replacement is the same as in cases with arthritis due to degenerative disease. In the other subgroup, the procedure for cup implantation resembles revision arthroplasty for acetabular loosening. The options for treating defects or deformities and the implants used are identical in both situations. Therefore the results should be compared with those of revision arthroplasty and not primary implantation. Scars, fibrotic changes in muscles, para-articular ossification, bone defects, residual deformities of the acetabulum, devitalized bone fragments or hindering previous implants make the surgical procedure more difficult and interfere with good results.

Total hip arthroplasty carried out after acetabular fracture is technically demanding. The prerequisite for a good result is to achieve primary stability of the acetabulum. Acetabular reconstruction is based, in the first place, on replacement of the missing bony tissue, and on providing conditions for correct alignment of the acetabulum and reliable primary and early secondary osteointegration. THA after acetabular fracture achieves poorer results than when it is indicated for degenerative disease. Key words: acetabular fracture, post-traumatic hip arthritis, total hip replacement.