The effects of extra-articular suture tension on contact mechanics of the lateral compartment of cadaveric stifles treated with the TightRope CCL or lateral suture technique.

OBJECTIVE

To determine the effect of suture tension on contact pressures in the lateral compartment of the stifle for the TightRope CCL((R)) (TR) and circumfabellar-tibial suture (LS) techniques.

STUDY DESIGN

Ex vivo biomechanical study.

SAMPLE POPULATION

Pelvic limbs (n=12) from dogs weighing 21-24 kg.

METHODS

A pressure sensor was used to record peak contact pressure (PCP) and mean contact pressure (MCP) and contact area (CA) in limbs mounted in a materials testing machine. Stifles were stabilized using either a TR or LS technique and the prosthesis was tensioned increasingly from 25 to 70 N. PCP, MCP, and CA were collected at each applied tension before and after applying an axial load of 150 N.

RESULTS

In the unloaded condition, LS stabilization resulted in a significant increase (P=.034) in PCP at >or=40 N tensions, whereas TR stabilization resulted in a significant increase (P=.047) in PCP at 70 N tension. There was a significant increase in CA at tensions >or=60 N in the LS group. No effect on MCP was noted. No significant differences in contact pressures were observed in the loaded condition. There were no significant differences in normalized PCP and CA between stabilization groups at any of the tension increment.

CONCLUSIONS

The application of high tension to the extra-articular prosthesis alters lateral compartment contact pressures in the unloaded stifle in this ex vivo model.

CLINICAL RELEVANCE

Over tightening of an extra-articular prosthesis may increase lateral compartment pressure at the time of surgery. The clinical implications of this finding are unknown, as weight bearing may negate any detrimental effect of high prosthesis tension.