Artikel
Biomechanical Analysis of the Tendon with Z-lengthening (TWZL) Construct: An Alternative Reconstructive Technique
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Autoren
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Jeffrey Greenberg
- Indiana Hand to Shoulder Center, Indianapolis, United States
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William J. Weller
- Campbell Clinic, Memphis, United States
| Veröffentlicht: | 6. Februar 2020 |
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Gliederung
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Objectives/Interrogation: An alternative to utilization of free tendon grafting is the Tendon With Z-Lengthening (TWZL) technique. This method utilizes the native tendon, z-lengthened and rotated on a distal juncture to provide length in cases of tendon deficiency. This technique obviates the need for tendon autograft and may allow for early active motion (EAM) protocols. This study evaluated the feasibility of the TWZL technique in cadaveric FDP tendons and biomechanically analyzed various suture constructs to determine the ideal one that could potentially allow an EAM rehabilitation protocol.
Methods: The FDP tendons of the index, middle and ring fingers harvested from 20 fresh frozen cadavers were utilized. 60 tendons were randomized into 5 different TWZL construct designs (Figure 1 [Fig. 1]).
Tendon-suture constructs using 3-0 Maxbraid® were tested on a servohydraulic testing machine until failure was observed on the load-elongation recording. Stress-strain graphs were created. Data points on maximum yield and load at 8% strain were recorded for each construct.
Results and Conclusions: The maximum yield data revealed construct #4 to have the highest overall mean load to failure at 150 N compared to all other constructs (p <0.0003).
Construct #4, at 59 N, had the highest mean load at 8% strain. Constructs #2, #3, and #4 were found to withstand a significantly higher mean load at 8% strain than constructs #0 and #1 (p < 0.0001). Comparison amongst constructs #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 standard deviation and confidence limit intervals that fell below the 45 N EAM threshold, whereas both constructs #2 and #4 had 95% confidence limits that fell no lower than 50 N.
In conclusion, the option of having a less morbid and simplified procedure for tendon reconstruction is attractive, especially if an EAM protocol can be initiated at time zero. This study provides evidence that the TWZL technique utilizing either construct #2 or #4 could provide sufficient strength for tendon reconstruction and subsequent early rehabilitation.
