Effects of a contoured articular prosthetic device on tibiofemoral peak contact pressure: a biomechanical study

Abstract

Many middle-aged patients are affected by localized cartilage defects that are neither appropriate for primary, nor repeat biological repair methods, nor for conventional arthroplasty. This in vitro study aims to determine the peak contact pressure in the tibiofemoral joint with a partial femoral resurfacing device (HemiCAP ® , Arthrosurface Inc., Franklin, MA, USA). Peak contact pressure was determined in eight fresh-frozen cadaveric specimens using a Tekscan sensor placed in the medial compartment above the menisci. A closed loop robotic knee simulator was used to test each knee in static stance positions (5°/15°/30°/45°) with body weight ground reaction force (GRF), 30° flexion with twice the body weight (2tBW) GRF and dynamic knee-bending cycles with body weight GRF. The ground reaction force was adjusted to the living body weight of the cadaver donor and maintained throughout all cycles. Each specimen was tested under four different conditions: Untreated, flush HemiCAP ® implantation, 1-mm proud implantation and 20-mm defect. A paired sampled t test to compare means (significance, P ≤ 0.05) was used for statistical analysis. On average, no statistically significant differences were found in any testing condition comparing the normal knee with flush device implantation. With the 1-mm proud implant, statistically significant increase of peak contact pressures of 217% (5° stance), 99% (dynamic knee bending) and 90% (30° stance with 2tBW) compared to the untreated condition was seen. No significant increase of peak contact pressure was evaluated with the 20-mm defect. The data suggests that resurfacing with the HemiCAP ® does not lead to increased peak contact pressure with flush implantation. However, elevated implantation results in increased peak contact pressure and might be biomechanically disadvantageous in an in vivo application.

Treatment of osteochondral defects of the talus

“…Becher et al compared implantation levels of a femoral condyle HemiCAP using human cadaver specimens. 43 Th ey concluded that protruding implantation led to substantially increased peak contact pressure, as also occurred in our single protruding implantation (specimen no. 11).…”

“…In particular, the periphery of the implant cap should be recessed because "edge-loading" may result in a poor outcome. 43,222 . Th e lateral part of the implant can be considered to be crucial because it is located on the weight-bearing talar dome articulating with the tibial plafond.…”

Effect of Implantation Accuracy on Ankle Contact Mechanics with a Metallic Focal Resurfacing Implant

“…Focal resurfacing with use of a metallic cap has been shown to be a promising alternative approach with which to avoid or delay joint replacement in middle-aged and older patients [14][15][16][17][18][19] . However, recent animal studies have suggested that articular damage can be associated with these implants [20][21][22] , especially in the case of surface-proud implantation.…”

Time-dependent behavior of cartilage surrounding a metal implant for full-thickness cartilage defects of various sizes: a finite element study

“…Both microfracture and metal implants damage the directly articulating cartilage, and remote places in the knee, but metal implants cause less damage than the microfracture technique (Custers et al 2009b). Contact pressures on the articulating surfaces from metal implants have been studied using human cadaveric knees, showing that position of the implant significantly affects the contact pressure (Becher et al 2008(Becher et al , 2009.…”