Novel metallic implantation technique for osteochondral defects of the medial talar dome. A cadaver study.
OBJECTIVE
A metallic inlay implant (HemiCAP) with 15 offset sizes has been developed for the treatment of localized osteochondral defects of the medial talar dome. The aim of this study was to test the following hypotheses: (1) a matching offset size is available for each talus, (2) the prosthetic device can be reproducibly implanted slightly recessed in relation to the talar cartilage level, and (3) with this implantation level, excessive contact pressures on the opposite tibial cartilage are avoided.


METHODS
The prosthetic device was implanted in 11 intact fresh-frozen human cadaver ankles, aiming its surface 0.5 mm below cartilage level. The implantation level was measured at 4 margins of each implant. Intraarticular contact pressures were measured before and after implantation, with compressive forces of 1,000-2,000 N and the ankle joint in plantigrade position, 10 dorsiflexion, and 14 plantar flexion.


RESULTS
There was a matching offset size available for each specimen. The mean implantation level was 0.45 (SD 0.18) mm below the cartilage surface. The defect area accounted for a median of 3% (0.02-18) of the total ankle contact pressure before implantation. This was reduced to 0.1% (0.02-13) after prosthetic implantation.


CONCLUSIONS
These results suggest that the implant can be applied clinically in a safe way, with appropriate offset sizes for various talar domes and without excessive pressure on the opposite cartilage.
Orthopedic Research Center Amsterdam, Department of Orthopedic Surgery, Academic Medical Center, University of Amsterdam, The Netherlands. c.j.vanbergen@amc.nl
Christiaan J A
CJ
van Bergen
Maartje
M
Zengerink
Leendert
L
Blankevoort
Maayke N
MN
van Sterkenburg
Jakob
J
van Oldenrijk
C Niek
CN
van Dijk
D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys; D000843:Ankle Joint / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena; D002102:Cadaver; D002358:Cartilage, Articular / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D020007:Implants, Experimental; D007595:Joint Prosthesis; D008297:Male; D008422:Materials Testing; D010007:Osteochondritis / Q000601:surgery; D019919:Prosthesis Implantation / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D013628:Talus / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*
D000497:Alloys