Comparative Biomechanical Characteristics of Modified Side-to-Side Repair and Modified Pulvertaft Weaving Repair - In vitro Study.

BACKGROUND

Strong surgical repair is the mechanical basis of early mobilization and prerequisite for biological healing following tendon grafting. Side to side and pulvertaft repairs were developed to meets these demands. However, these techniques have later been modified to improve the strength of repair but their characteristics have not been compared.

METHODS

We compared biomechanical strength of the modified side-to-side (SS) repair with the modified Pulvertaft (PT) repair technique in turkey tendons keeping overlap length, anchor points, type of suture, suture throw and amount of suture similar. Two investigators performed 34 repairs during one summer month to test the tensile strength of the repair using mechanical strength testing machine. Variables measured were maximum load, load to first failure, modulus, load at break, mode of failure, site of failure, tensile strain, tensile stress. The statistical comparison was carried by Levene's test and T test for means.

RESULTS

The mean maximum load for modified SS repair was 50.3 (SD 13.7) N and modified PT repair was 46.9 (SD 16.4) N. The tensile stress at maximum load for SS and modified PT repair was 4.7 (SD 4) MPa and 4.2 (SD 3) MPa respectively. The suture cut through was the commonest mode of failure.

CONCLUSIONS

We found no statistical difference between 2 repairs in load at which they started failing (p = 0.16), and maximum load repairs could withstand (p = 0.35). Our study uniquely compares two techniques under standard conditions, and contrary to existing evidence found no difference. However, in our opinion the number of anchor points may have a greater impact than number of weaves on the strength.