Tendon With Z-Lengthening Technique and Construct Assessment: A Biomechanical Study for Use in Tendon Reconstructions.

PURPOSE: Tendon reconstruction is frequently required under conditions of tendon deficiency. The authors sought a technique that could obviate the need for tendon harvest yet meet the minimum load of 45 N required for an early active motion protocol. This study was designed to determine the ideal suture construct utilizing the tendon with Z-lengthening (TWZL) technique.

METHODS

Sixty fresh-frozen cadaveric flexor digitorum profundus tendons of the index, middle, and ring fingers were randomized into 5 different TWZL construct designs using 3-0 braided polyethylene suture. Constructs were tested on an electromechanical actuator until failure was observed on the load-elongation recording. Data points on maximum yield and load at 8% strain were recorded for each construct.

RESULTS

The maximum yield data revealed the construct with a 4-core suture type configuration (construct #4) had the highest overall mean load to failure at 150 N compared with all other constructs. The construct with the highest mean load at 8% strain was that with a 4-core type repair (construct #4) at 59 N. The constructs with Krackow locking sutures (constructs #2, #3, and #4 were found to withstand a significantly higher mean load at 8% strain than those without Krackow sutures (#0 and #1). Comparison among constructs with Krackow locking sutures #2 (56 N), #3 (48 N), and #4 (59 N) did not show a significant difference in mean load at 8% strain. Construct #3, however, had an SD and 95% confidence interval that fell below the 45 N early active motion threshold, whereas both #2 and #4 had 95% confidence intervals that fell no lower than 50 N.

CONCLUSIONS

This study provides evidence that the TWZL technique utilizing either construct #2 or #4 could provide sufficient strength and reproducibility for tendon reconstruction.

CLINICAL RELEVANCE: The study describes the application of the TWZL technique for utilization in tendon reconstruction and quantifies differences in the yield strengths of the 5 proposed constructs.