Meniscal repair: The current state and recent advances in augmentation

Abstract

Meniscal injuries represent one of the most common orthopedic injuries. The most frequent treatment is partial resection of the meniscus, or meniscectomy, which can affect joint mechanics and health. For this reason, the field has shifted gradually towards suture repair, with the intent of preservation of the tissue. "Save the Meniscus" is now a prolific theme in the field; however, meniscal repair can be challenging and ineffective in many scenarios. The objectives of this review are to present the current state of surgical management of meniscal injuries and to explore current approaches being developed to enhance meniscal repair. Through a systematic literature review, we identified meniscal tear classifications and prevalence, approaches being used to improve meniscal repair, and biological- and material-based systems being developed to promote meniscal healing. We found that biologic augmentation typically aims to improve cellular incorporation to the wound site, vascularization in the inner zones, matrix deposition, and inflammatory relief. Furthermore, materials can be used, both with and without contained biologics, to further support matrix deposition and tear integration, and novel tissue adhesives may provide the mechanical integrity that the meniscus requires. Altogether, evaluation of these approaches in relevant in vitro and in vivo models provides new insights into the mechanisms needed to salvage meniscal tissue, and along with regulatory considerations, may justify translation to the clinic. With the need to restore long-term function to injured menisci, biologists, engineers, and clinicians are developing novel approaches to enhance the future of robust and consistent meniscal reparative techniques.

Keywords: biologics; materials; meniscectomy; meniscus; repair.

FIGURE 1

Schematics of prevalent meniscal tears. Schematics of radial, longitudinal, and horizontal tears, in both axial and cross-sectional views. Arrows indicate the progression of these smaller tears to larger and more complex versions

FIGURE 2

Meniscus tear observed incidence rates (% of observed tears within each study) from the literature. (A) Rates for affected meniscus (medial, lateral, or both) in adult (including adults with ACL reconstruction (+ACLR) and Athletes) and pediatric populations. Data from Jackson et al. (2019), Robinson et al. (2011), El Mansori et al. (2018), Kim et al. (2019), Ridley et al. (2017), Christino et al. (2019), Baker et al. (1985), Terzidis et al. (2006).^– (B) Rates by region (anterior, body, posterior, multiple) in adult (including +ACLR and Athlete) and pediatric populations. Data from Jackson et al. (2019), El Mansori et al. (2018), Kim et al. (2019), Terzidis et al. (2006).^,– (C) Rates by vascular zone (outer = red-red, intermediate = red-white, inner = white-white, multiple) in the medial and lateral menisci in adult populations. Data from Terzidis et al. (2006). (D) Rates by tear type and affected meniscus (T, M, and L) in general adults, ACLR+ adults, and adults who are athletes. Data from Jiang et al. (2017), El Mansori et al. (2018), Terzidis et al. (2006).^,, ACL, anterior cruciate ligament; L, lateral; M, medial; T, total incidence

FIGURE 3

Summary of systematic review findings. (A) Publication history of papers included in the systematic review from 1988 to 2020. Papers categorized across technique, biological, material, and hybrid (combined biological/material) interventions. (B) Graph of prevalent injuries/models (annulus model and circular lesion) utilized in studies. (C) Graph of model systems used in studies in systematic review (middle) and expansions of explant species (left) and large animal model species (right). Each circle presents one study that has utilized that system or model (n = 107)

FIGURE 4

Schematic and recommendations for meniscus repair techniques. (A) (Left) inside-out, (middle), all-inside, and (right) outside-in techniques. (B) Repair techniques (inside-out, all-inside, outside-in) recommended for major tear types discussed (radial, longitudinal, horizontal, ramp [longitudinal tear in the peripheral capsular attachment of the posterior horn], root). Relative use (acceptable, very common, not suitable, etc.), gold standards, and risks are also detailed. Recommendations obtained from the following sources for inside-out (Muckenhirn et al., 2017; Nelson et al., 2013; Kang et al., 2019)^–, all-inside (Kang et al., 2019; Negrin et al., 2018)^,, outside-in (Menge et al., 2016; Steiner et al., 2018; Dave et al., 2012; Thompson et al., 2014)^–, and transtibial techniques (Chahla et al., 2016; LaPrade et al., 2015)^,

FIGURE 5

Statistics regarding technique-based studies for meniscus repair. (A) Technique advancement by category, (B) model system, and (C) injury type

FIGURE 6

A look at the intended functions of biological intervention. (A) Schematic of four major themes in biological repair. (B) Statistics reflecting the prevalence of each theme

FIGURE 7

A schematic of the types of material intervention for repair. (A) Schematic of four major themes in materials-based repair. (B) Statistics reflecting the prevalence of each theme

FIGURE 8

Statistics of biological, hybrid, and material interventions for meniscus repair. (A) Model systems and (B) injury models in each type of intervention