# Transtibial repair of medial meniscus posterior root tears: Interference screw fixation improves primary stability in a porcine model

## TL;DR

This study found that using an interference screw improves the stability of medial meniscus repairs in a pig model compared to another method.

## Contribution

The study introduces new biomechanical evidence that interference screw fixation is more stable for medial meniscus root repairs in a porcine model.

## Key findings

- Interference screw fixation showed significantly lower elongation and higher stiffness than Endobutton fixation.
- Group 1 (IS + SutureTape) had the highest maximum load to failure, while Group 2 (IS + FiberWire) had the lowest.
- Endobutton with FiberWire had the highest yield load, but interference screw with SutureTape performed best overall.

## Abstract

This porcine study aimed to evaluate surgical refixation methods for medial meniscal root tears. We compared biomechanical characteristics of tibial fixation using an interference screw (IS) and fixation with an Endobutton (EB).

Forty porcine knee joints were prepared with radial section for a complete detachment of the medial meniscus posterior root (MMPR), followed by transtibial pull‐out refixation. Specimens were randomly assigned to four groups based on fixation method and suture material: IS (STORZ PEEK Power Fix 7 × 25 mm, Storz, Tuttlingen, Germany) or EB (Smith & Nephew, London, UK), each combined with two single stitch sutures of either FiberWire size 2 (FW; Arthrex, Naples, USA) or SutureTape 1.3 mm (ST; Arthrex, Naples, USA). Constructs were subjected to cyclic loading (1000 cycles), followed by load‐to‐failure testing. Biomechanical parameters assessed included elongation, stiffness, yield load, maximum load to failure and failure mode.

Fixation with IS (Groups 1 and 2) demonstrated significantly lower elongation and greater stiffness compared to EB fixation (Groups 3 and 4). Specifically, Group 2 (IS + FW) showed significantly reduced elongation versus both EB groups (p < 0.05). Group 1 (IS + ST) exhibited significantly higher stiffness than Groups 3 and 4 (p < 0.05). Yield load and maximum load to failure varied depending on the fixation method and suture type. Group 4 (EB + FW) had the highest yield load, followed by Group 1 (IS + ST) and Group 3 (EB + ST). Group 2 (IS + FW) had a significantly lower yield load compared to Group 4 (p < 0.05). Furthermore, Group 2 demonstrated significantly reduced maximum load to failure compared to both Group 1 and Group 4 (p < 0.05). Overall, Group 1 (IS + ST) achieved the highest maximum load to failure, whereas Group 2 (IS + FW) showed the lowest.

In this porcine model, transtibial pull‐out repair of MMPR tears using IS demonstrated superior primary biomechanical stability compared to EB fixation. Constructs with IS showed reduced elongation and increased stiffness under load. However, to confirm the clinical relevance of these findings, further investigations in clinical settings are necessary.

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