ULTRASONIC ABLATION OF FEMORAL CEMENT FOR REVISION TOTAL HIP ARTHROPLASTY: EARLY EXPERIENCE

Abstract

Purpose: Removing cement for revision total hip arthroplasty is always a challenge. The OSCAR device (Orthosonics Ltd UK) provides an elegant solution. We conducted a prospective study of ultrasound ablation using this device in 19 patients undergoing revision total hip arthroplasty to assess feasibility.

Material and methods: Between March 1999 and January 2001, 17 patients, ten women and seven men underwent revision of their femoral component for aseptic loosening (14 cases) or infection (five cases). The Vives criteria as modified by SOFCOT were six grade 1, six grade 2, five grade 3 and two grade 4. The femoral stem removed had a standard length in 17 cases and measured 250 mm in one. The cement obturated the femur in one case with a proximal misinsertion. On the average, the terminal plug went 40 mm beyond the tip of the stem. Trochanterotomy was used ten times and anterior approach in nine. Two ultrasound probes were used: scraper probes that removed cement from the walls and a perforating probe when needed to remove the terminal plug. We recorded the time needed to remove all the cement, the ease or difficulty of the process, the presence of misinserted cement, need for other methods (new window, femorotomy), duration of the hospital stay, and delay to weight-bearing with crutches. The quality of the cementing and presence of cement overflow were determined on plain radiographs. All patients were reviewed for this work.

Results: It took less than 60 min to remove the cement in 14 cases and from 60 to 90 min for four cases; the cement could not be totally removed in one case. There was one fracture (grade 4 during a third revision operation). The end plug was removed under good conditions in 14 cases. The femoral stem could be recemented in nine cases using a longer stem in five. Cementing was satisfactory in 12 cases. Deferred surgery was required for the five cases with infection; in two cases the cement persisted at the second operation requiring a new ablation process. There were no cases of misinsertion. Mean hospital stay was 10.1 days and weight-bearing was authorised on the third day for patients without infection. At a mean follow-up of 8.5 months, there have been no cases of revision, fracture or stem migration.

Discussion: The rate of total hip arthroplasty revision is an estimated 10%. The risk of an incident during cement ablation is an estimated 18% to 28%. Advantages of the ultrasound technique include: shorter operative time, simple material, less danger for weak bone as noted in our patients, absence of the need for complementary fixation, shorter hospital stay, and lower cost. Histology studies have demonstrated the absence of deleterious effects of ultrasound ablation explaining the good quality of recementing (12 cases).

Conclusion: Ultrasound ablation of femoral cement is effective for aseptic revision. In case of infection, the presence of persistent cement might be related to recurrent infection.