SLR - November 2014 - Julie Riley

Biomechanical Evaluation of Various Suture Configurations in Side-to-Side Tenorrhaphy

Reference: Emilio Wagner, MD; Cristian Ortiz, MD; Pablo Wagner, MD; Rodrigo Guzman, PT; Ximena Ahumada, MD; Nicola Maffulli, MD, MS, PhD, FRCP, FRCS(Orth), FFSEM. Biomechanical Evaluation of Various Suture Configurations in Side-to-Side Tenorrhaphy. J Bone Joint Surg Am, 2014 Feb 05;96(3):232-236.

Scientific Literature Review

Reviewed By: Julie Riley, DPM
Residency Program: St. Elizabeth’s Medical Center, Brighton, MA

Podiatric Relevance: Tendon surgery, whether as a primary or adjunctive component of a surgical case, is commonly performed in podiatric medicine. Post-operative protocols differ between practitioners but many agree that early range of motion and weight bearing is advantageous to prevent adhesions or stiffness. There are many different kinds of sutures and types of stitch available for a podiatrist to choose from to perform a given tenorrhaphy or tendon transfer and it is up to the discretion of the practitioner to choose the best one in a given situation. Utilizing evidence based medicine to support the suture selection as well as to guide post-operative care is important for making educated decisions. Commonly used in practice is end-to-end tenorrhaphy and many different factors have been extensively studied with this approach. Examples include number of strands of suture bridging the repair, suture caliber, and placement of knots. Side to side tenorrhaphy which is commonly utilized in many podiatric procedures does not have as much data.

Methods: Porcine flexor digitorum tendons were harvested and utilized for this prospective experiment. All tendon segments were 8 cm long by 1 cm and sutured, utilizing FiberWire, with an overlap of 3 cm between each segment. All of the constructs were standardized with respect to number of connection points between tendons as well. The four suture configurations tested were simple eight, pulley, vertical mattress, and running locked and there were eight tenorrhaphies per group. The configurations were biomechanically stressed on a tensile testing machine in a cyclical loading fashion at a rate of 1 mm/sec with 15-35 N. They were then monotonically elongated to failure at this same distention rate. Outcomes for the cyclic loading phase included cause of failure and tendon distension during loading. Outcomes for the monotonic phase included cause of failure, load to first failure, max load resisted prior to 1 cm of distension, load resisted at 1 cm distension, and repair stiffness. Causes of failure included suture breakage, knot loosening, or tendon stripping. The results were recorded, graphed, and analyzed using wavemetrics software. Descriptive statistical tests were used to analyze and confirm the characteristics and significance of the results.

Results: No failure or slippage of any of the four constructs was noted in the cyclic loading phase. During the monotonic loading phase, all failures were due to tendon slipping at the repair site. The vertical mattress configuration had a significantly lower maximum load to failure, max load resisted prior to 1 cm distension, and load resisted at 1 cm distension than the other three types. No significant differences were seen among the other three configurations in these categories. Evaluation of construct stiffness utilizing a load versus distension graph showed that the running locked suture groups were stiffer than the vertical mattress groups.

Conclusions: The importance of optimum dynamic balance in foot and ankle cases has long been established. When planning surgical procedures in which tendon transfers, tendon advancements, or tenorrhaphies are necessary, it is important to feel confident in your fixation. This study looks at the ability of different suture configurations using a commonly used suture to examine if they can withstand physiologic demands similar to those in a post-operative period. The results suggest that early rehabilitation protocols and passive range of motion are mechanically safe utilizing any of the four suture configurations. Vertical mattress, although found to be the weakest overall, still required a stress of 140 N before failure. With a stress of 398 N being required for failure of the pulley group, this would seem to be the best choice for early weight bearing and rehabilitation. In conclusion, many factors go in to choosing suture types and configurations, and having research in this area is important in lending to these evidence based decisions. 

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