Biomechanical Comparison of an All-Inside Meniscal Repair Device Construct Versus Pullout Sutures for Arthroscopic Transtibial Repair of Posterior Medial Meniscus Root Tears: A Matched-Pair Cadaveric Study

Abstract

Background: Meniscus root repairs are important for restoring knee function after a complete meniscus root tear. Various suturing patterns have been proposed for the root repair. The 2-simple-stitches (TSS) method is currently the preferred technique, as it is simplest to perform and allows the least displacement of the meniscus root.

Purpose: To compare the biomechanical properties of a posterior medial meniscus transtibial root repair consisting of an all-inside meniscal repair device (AMRD) construct with the TSS pullout suture pattern.

Study design: Controlled laboratory study.

Methods: Ten pairs of cadaveric medial menisci were prepared with 1 of the 2 constructs. The constructs were randomized between pairs. All constructs were subjected to preloading with 2 N for 10 seconds and then cyclic loading from 5 N to 20 N for 1000 cycles at a frequency of 0.5 Hz. Subsequently, the menisci were loaded to failure at a rate of 0.5 mm/s. All loads were applied in-line with the circumferential meniscal fibers near the posterior medial meniscal horn.

Results: The mean yield load and stiffness were similar for both constructs. The elongation after cyclic loading was greater for the AMRD. The displacement at both yield load and ultimate failure were also higher for the AMRD. The ultimate failure load of the AMRD was also significantly higher. During load to failure, the mode of failure in the AMRD was heterogeneous. All the TSS constructs failed by suture cutout.

Conclusion: Posterior medial meniscus root repairs using both the AMRD and TSS constructs have elongation under the biomechanically acceptable threshold of 3 mm. The stiffness and yield loads indicate similar mechanical properties of the constructs. However, the significantly higher elongation for the AMRD leaves the TSS method as the preferred option for transtibial repairs. Despite this, the AMRD construct may still represent a viable alternative to the TSS suture pattern, comparable to alternative suture patterns with similar limitations.

Clinical relevance: The AMRD construct may represent a viable alternative to the TSS suture pattern.

Keywords: all-inside meniscal repair device; biomechanical testing; meniscus root tear; pullout suture; root repair.

Figure 1.

Images of (A) the TSS construct and (B-D) the AMRD construct. (C) The position of the introducer for the first device is shown. (D) More detail for the application of the AMRD is shown schematically. AMRD, all-inside meniscal repair device; TSS, 2-simple-stitches.

Figure 2.

Photographs of test fixture showing (A) the meniscus fixed in the test clamp and the sutures tied over the 8-mm pin, which is fastened to the 1-kN load cell, and (B) the distances between the insertion point of sutures in the meniscus and the pin at the start of each cyclic test.

Figure 3.

Representative cyclic loading curve using WaveMatrix. The inset details the cyclic nature of loading. The elongation after cyclic loading is annotated in red.

Figure 4.

Representative load-to-failure curve collected using WaveMatrix. Shown are distinct yield and ultimate failure loads. The stiffness was calculated as the slope of the red dashed line.

Figure 5.

Boxplot showing the elongation after cyclic loading of the constructs. The box represents the interquartile range (IQR) (quartile 1 [Q1] to Q3), the black diamond represents the mean, the horizontal line the median values, and the error bars represent the minimum and maximum (calculated as Q1 – 1.5 × IQR and Q3 + 1.5 × IQR). The circle indicates an outlier. AMRD, all-inside meniscal repair device; TSS, 2-simple-stitches.

Figure 6.

Boxplot showing the (A) ultimate failure load and (B) displacement at ultimate failure load. The box represents the interquartile range (IQR) (quartile 1 [Q1] to Q3), the black diamond represents the mean, the horizontal line the median values, and the error bars represent the minimum and maximum (calculated as Q1 – 1.5 × IQR and Q3 + 1.5 × IQR). AMRD, all-inside meniscal repair device; TSS, 2-simple-stitches.

Figure 7.

Boxplot showing the (A) yield load and (B) displacement at yield load for the all-in meniscal repair device and 2-simple-stiches constructs. The box represents the interquartile range (IQR) (quartile 1 [Q1] to Q3), the black diamond represents the mean and horizontal line the median values, and the error bars represent the minimum and maximum (calculated as Q1 – 1.5 × IQR and Q3 + 1.5 × IQR). AMRD, all-inside meniscal repair device; TSS, 2-simple-stitches.