Categorize the existing clamps used for tensile test of human graft- a systematic review

Abstract

Background: The use of tendon allografts for orthopedic repair has gained wide acceptance in recent years, most notably in anterior cruciate tendon reconstruction. Multiple studies support the use of tendon allografts and the benefits of its use are well accepted and understood. One of the important criteria of the use of tendon allografts is statistically similar histological and biomechanical properties to autographs. The aim of this systematic literature review is to investigate and categorize existing clamps used in the determination of the biomechanical properties of tendons such as maximum load, maximum strength, modulus of elasticity, ultimate strain, and stiffness. A variety of clamps for use during the endurance test of tendons were categorized according to the temperature used during the measurement. The clamps are divided into three groups: room temperature, cooled and heated clamps. The second goal of our review is to overview of clamps on the following aspects: name of clamp, author and date, type of clamps, type of endurance test (static or dynamic), type preloading (dynamic or static), type of tendon and measured and calculated parameters, and summarize in Table 3, as a comprehensive catalogue.

Methods: This systematic review was carried out in keeping with the PRISMA 2020 E&E and the PRISMA-S guidelines and checklists. A search was conducted for publications dating between 1991 and February 28th 2022 through three electronic databases (Web of Science, Scopus, and PubMed). We used Critical Appraisal Skills Program checklist to check the quality of included articles.

Results: The database search and additional sources resulted in 1725 records. 1635 records eliminated during the screening for various reasons (case report, other languages, book chapter, unavailable text/conference abstract, unrelated topic). The number of articles used in the final synthesis was 90. A variety of clamps for use during the endurance test of tendons were identified and categorized according to the temperature used during the measurement. Based on this, the clamps are divided into three groups: room temperature, cooled or heated clamps.

Conclusions: On the basis of the systematic literature review, mechanical parameters determined by usage with cooled clamps proved to be more reliable than with those at room temperature and with heated clamps. The collected information from the articles included name of clamp, author and date, type of clamps, type of endurance test (static or dynamic), type preloading (dynamic or static), type of tendon and measured and calculated parameters given in Table 3. summarized. The main advantage of the cooled clamps is that there is no limit to the type and length of the tendon. This study provides an overview of clamps and does not represent the modernity of any method.

Keywords: Biomechanical endurance test of tendon; Clamp type; Mechanical properties; Tendon.

Fig. 1

Metal U-shaped frames [115, 116]

Fig. 2

Custom-designed clamps for Canine PLT segments [117]

Fig. 3

Images of factory clamps (Zwick/Roell) a) Osseus blocks potted in polyurethane  fixed into the clamps of the testing device [107]

Fig. 4

Wedge-shaped factory clamps [110] A special case is when wedge-grip clamp use involves silicone or some kind of artificial resin at both ends to ensure the connection between clamp and tendon [56, 85, 106] (Fig. 5)

Fig. 5

Wedge-grip clamps [56, 106] Several articles use polymer-encapsulated aluminum clamps to achieve better adhesion between the tendon and the clamp (Fig. 6). One of the advantages of the system is that it can be expanded by strain gauges [–79, 102]

Fig. 6

Aluminum grips with polymer liners and strain gauge [–79] There are articles that do not put any additional material between the ligament and the clamp, using only the factory “serrated” surface of the clamp to prevent slipping (Fig. 7). [35, 62] [49, 93]. [99, 103, 111]

Fig. 7

“Serrated” surface [35, 49, 62, 93]. [99, 103, 111]

Fig. 8

Testing configuration for single-row (a) and double-row (b) screw fixtures [69, 108]

Fig. 9

Cooled clamps with different ice chambers a) custom-designed clamp [42] b) factory clamp [65]

Fig. 10

Screwed custom clamps with aluminium chamber for dry ice [73]

Fig. 11

Test device with clamps, insulation, carbon composite rod, load cell, sample and thermocouple [114]

Fig. 12

Testing chamber with a PTB specimen mounted in custom grips, showing.eaters used to maintain the phosphate buffered saline at 37°C [81]

Fig. 13

Biochamber used for cyclic loading in solution at 37°C [104]