The ESKA TAR is a non-constrained, fixed-bearing, two-component prosthesis that was designed in Germany for cementless implantation between 1985 and 1989.1,2  It has a shallow groove on the talar component that is congrous to the ultra-high-molecular-weight polyethylene (UHMWPE) bearing fixed to the tibial prosthesis.  The following features were included to improve the biomechanics of the ankle replacement:

  • Cementless implantation and porous-structured implant surface for faster osteointegration
  • Shear force reduction and rotational force control by shape design of both metallic components
  • Easy replacement of the polyethylene without disturbing prosthesis anchoring.1,2

Because of the ridge-like shaping and its transverse anchoring peg in both metallic components, a lateral approach with fibular osteotomy or in special cases, a medial malleolar approach is used for component implantation.

In 2001, the prosthesis designer, Dr. Rudigier, published short-term results of 56 patients treated with the ESKA prosthesis since 1990.  Forty of 56 patients were reviewed at a minimum follow up of 1 year.  All patients experienced significant pain relief, improved ankle ROM and ability to walk, and showed functional improvement as assessed by the Kofoed ankle score.  In two cases, deep infection led to prosthesis removal and conversion to ankle fusion.  Another patient showed painful progressive ossification of the joint capsule resulting in ankle fusion.  The same patient cohort was again reviewed at a longer follow up and the results were published in another two studies.3,5  The authors reported a significant improvement of the Kofoed ankle score from 37.6 points preoperatively to 90.4 points postoperatively. Of 12 TARs performed 10-15 years before, 8 (67%) remained in situ (2 early deep infections, 2 aseptic loosenings).  In 20 implants inserted 5-10 years before, 3 were revised, leaving 17 (85%) in situ functioning well.  None of the implants with a follow-up of 1-5 years failed.  No results from independent authors have been published.

In summary, the limited studies performed by ESKA prosthesis designers reported favorable mid-term results with improved ankle ROM, pain relief, and ability to walk long distances postoperatively.3-5  However, the authors conceded that this surgery should be limited to only highly experienced foot and ankle surgeons due to the demanding lateral approach with fibular osteotomy.  As with the BOX TAR, published results have come from only the prosthesis designers.  Thus additional, independent analyses of ESKA efficacy are needed.

References

  1. Rudiger,J.: Ankle replacement by the cementless ESKA endoprosthesis. Tech Foot & Ankle, 4:125-136, 2005.
  2. Rudiger,J., Menzinger,F., and Grundei,H.: 14 Jahre Erfahrungen mit der zementfreien ESKA-Sprunggelenksendoprothese. Fuss Sprungg, 2:65-75, 2004.
  3. Rudigier,J.: Ankle replacement by the cementless ESKA endoprosthesis. Tech Foot & Ankle, 4:125-136, 2005.
  4. Rudigier,J., Grundei,H., and Menzinger,F.: Prosthetic replacement of the ankle in posttraumatic arthrosis: 10-year experience with the cementless ESKA ankle prosthesis. Eur J Trauma, 27:66-74, 2001.
  5. Rudigier,J., Menzinger,F., and Grundei,H.: 14 Jahre Erfahrungen mit der zementfreien ESKA-Sprunggelenksendoprothese. Fuss Sprungg, 2:65-75, 2004.