OTA 1997 Posters - Pelvic & Acetabular Fractures

Acetabular T-type Fracture - Factors Determining the Outcome

Alex Gänsslen, T. Pohlemann, T. Hüfner, H. Tscherne

Unfallchirurgie, MHH, Hannover, Germany

Purpose: Acetabular T-type fractures are rare injuries. In his series, Letournel only found 7% in this fracture group. The main factor for good or excellent long term outcome was the quality of initial reduction, i.e. the relocation of the femoral head under a sector of roof of sufficient size. The aim of the present study was to evaluate factors determine the long-term outcome after this specific fracture type.

Methods: Between 1972 and 1993, 70 patients with acetabular T-type fractures were treated at our institution. Clinical parameters (time of reduction, type of dislocation etc.), the operation report and primary x-rays concerning additional acetabular and femoral head lesions (fracture modifiers: e.g. impression zones, intraarticular fragments, chondral lesions) were analyzed. Eight patients died during clinical course, a 2-year (mean 4 years) follow-up was possible in 48 patients (77%). Besides an orthopaedic examination, a detailed radiological analysis (quality of reduction, type of osteoarthritis, femoral head necrosis, heterotopic ossification, etc.) of postoperative and follow-up x-rays was performed. The overall incidence, the prognosis and the type of degenerative changes was recorded. A poor outcome was defined as severe osteoarthritis, severe femoral head necrosis or Brooker type III-IV ossifications.

Results: Seven patients had infratectal (62B21), 16 juxtatectal (62B22) and 25 transtectal T-type (62B23) fractures. Overall 11 patients had impressions zones of the femoral head, 23 of the acetabulum, intraarticular fragments were found in 18 patients, 25 patients had comminution zones and 30 patients had an additional posterior wall injury. Postoperative reduction in 39 patients was anatomic in 15, a step or gap up to 4mm was present in 19 patients, 5 patients had gaps of 4mm (3). Analysis of postoperative reduction versus radiological outcome showed 21% poor results after anatomic reconstruction of the joint vs. 42% with a gap/step of > 1mm. There was a strong correlation between the number of additional fracture markers and the outcome. A poor outcome was found in 12.5% after T-type fractures without and 10% with one additional fracture marker. An increasing rate was found with two (20%), three (40%) and four (62.5%) additional fracture markers. In the group with 3 additional modifiers, 86.7% had an additional posterior wall fracture, 73.3% had acetabular comminution and 66.7% had acetabular impressions. In the group with 4 additional modifiers all patients had impression zones and comminution zones of the acetabulum and an additional posterior wall fracture, 62.5% showed intraarticular fragments.

Conclusion: Besides quality of reduction, prognostic factors influencing the outcome are impression zones of the acetabulum, comminution zones of the acetabulum and additional posterior wall fracture.