Fig 1.
Tenorrhaphies using the Woven-Fridén technique on human tendons.
Representation of specimens with variable overlap of the donor (top) and the recipient tendon (bottom) at 1.5 cm (left), 2 cm (middle) and 3 cm overlap (right) respectively.
Fig 2.
Comparison of the ultimate load of tenorrhaphies with 1.5 cm, 2 cm and 3 cm overlap (experimental groups, single-color bars) with native tendons (control group, crosshatched bar).
Data are expressed as means, bars with standard deviations are indicated. Different superscripts indicate statistically significant differences among the groups (p < 0.05 for 1.5 cm vs. 2 cm and for 3 cm vs. native; p < 0.001 among the remaining groups). For the control group, 10 native tendons were tested. For the experimental groups with 2 cm and 3 cm overlap 10 samples were tested respectively, for 1.5 cm overlap 9 samples were tested.
Fig 3.
Comparison of the stiffness of tenorrhaphies with 1.5 cm, 2 cm and 3 cm overlap (experimental groups, single-color bars) with native tendons (control group, crosshatched bar).
Data are expressed as means, bars with standard deviations are indicated. Different superscripts indicate statistically significant differences between groups at p < 0.001 and for 2 cm vs. 3 cm at p = 0.001. For the control group, 10 native tendons were tested. For the experimental groups with 2 cm and 3 cm overlap 10 samples were tested respectively, for 1.5 cm overlap 9 samples were tested.
Table 1.
Determined (bold) and extrapolated by formula 3 (italic) ultimate loads with corresponding safety factors for tenorrhaphies of variable overlap.
Fig 4.
Load bearing capacity of tenorrhaphies in Woven-Fridén (WF) suture technique as a function of the overlap length of the tendons.
The graph Gf (blue) illustrates the relation between overlap length in mm of WF tenorrhaphies (x-axis) and the corresponding ultimate load in N (y-axis). Each point in the coordinate system represents one sample (blue dots). The green line represents the greatest ultimate load expected (corresponding to the ultimate load of native tendons, i.e.control group). It can be approximated to 435 N. The red line represents the minimum required load capacity of the tenorrhaphies (corresponding to the maximum force expected by contraction of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) muscles). It is given by Ward et al. as approximately 69 N [31]. The intersection of the graph at the x-axis (x0) represents the beginning of the definition range, as no WF tenorrhaphies can be performed below this threshold (in case of too little tendon overlap). Therefore, no load bearing capacity is to be expected at this point.