Innovating for Longevity: Meniscus Tear Repair with Tissue Adhesives
By
Gabriela Voskerician, PhD
We all aspire to healthier, active, and longer lives. Meniscus tears are a direct result of such aspirations. With a more active lifestyle, as well as anincrease in life expectancy, the incidence of meniscus tears has seen a significant rise. As a result, patients demand solutions that will keep them“in the game” for as long as possible…and beyond. As a result, a number of solutions have been proposed, developed, and applied in meniscus repair, with variable levels of success.
Dr. Buma and his colleagues from Radboud University Nijmegen Medical Centre, University of Twente, and University Medical Centre Groningen, The Netherlands, offer a first look at the current state of the art as well as current efforts in meniscus repair with tissue adhesive [click here todownload the article].
From the start, the article sets the stage forunderstanding the problem. Dr. Buma and his colleagues diligently and logically describe the meniscus mechanical and physiological properties, along with empirical data on tear characteristics. Through this approach, the group lays a foundation for evaluating current repair procedures in the context of the actual needs of the tissue being repaired. With a clear understanding of the problem and needs, the group describes the limitations of procedures such as suturing or anchoring. The benefits of using tissue adhesives are, then, introduced.
One interesting aspect of meniscus damage is age-related degeneration. While the general appearance of the meniscus might be similar among various age groups, the article does not directly address how meniscus degeneration progresses throughout adulthood. Dr. Buma and his colleagues explained that a healthy meniscus of an adult contains approximately 72% of water and 28% of organic matter [majority collagen type I]. Between the age of 30 to 80, the collagen presence remains constant, followed by a decline after the age of 80. Meniscus aging is further characterized by adecrease in the non-collagenous matrix proteins, and a reduction along with re-organization of cellular presence into clusters.
Figure 3 of the article presents, at a glance, the standardized mechanical properties of the meniscus as reported in the literature. Interestingly, the cited literature had evaluated menisci mechanical properties from a very wide range of adults, 26-73 years of age. It appears that in these papers, themechanical properties reporting relies on a consensus average of the existing data, regardless of age. To some extent, those findings contrastwith the expected mechanical properties variability reported by other groups that focused on mapping tissue aging. Dr. Buma clarified that, with aging, the meniscus becomes stiffer. Through the process of aging, the meniscus experiences a gradual loss of cellularity, followed by appearance of voids (empty spaces)together with an increase in the fibrous tissue to elastic tissue ratio. The notable outcome is appearance of tears within the tissue, which are difficult to repair through conventional surgical methods, such as suturing. The critical aspects to consider here are: (a) recognize that the meniscus mechanical properties depend on the overall patient health status [other co-morbidities, e.g., diabetes, arthritis] and lifestyle [active/non-active]; and (b) to determine the purpose of a repair, the age of the patient, extent of damage, and especially the patient lifestyle before choosing asurgical repair route.
Further, it was puzzling to learn that while the fibrin adhesives used in meniscus tear repair reported above produced average outcomes with very low long-term recurrence rates, this specific adhesive has met resistance to adoption. Dr. Buma elaborated on this low adoption rate by explaining that the reported outcomes used fibrin glue as an adjunct to suturing. Further, the authors note a number of additional limitations disfavoring the use of fibrin glue adhesives as a primary repair venue. They include poor mechanical properties, need to immobilize the repaired joint to allow the fibrin adhesive to absorb into the meniscus tear, potential transmission of disease, and high cost.
Photocrosslinkable adhesives are fascinating in their versatility of structure-function as well as versatility of application. While applied to skin and heart, these adhesives have not been evaluated in the context of meniscus repair. The authors elaborated on the future of these versatile adhesives in the meniscus repair space. The general adhesion mechanism of the photocrosslinkable adhesives is covalent bonding and mechanical interlocking on the exposed tissue surface. The mechanical and physiochemical properties [e.g., hydrophilicity, degradation rate] of these adhesives can certainly be tuned to meniscus tear repair needs. The group recognizes that a primary obstacle tothe adoption of photocrosslinkable adhesives for mainstream meniscus repair is the availability of the needed light source in situ to initiate curing. This limitation is a result of the current majority adoption of arthroscopic procedures that limit the size of instruments and visual field available to the surgeon during the procedure.
In this review article, Dr. Buma and his colleagues share with the scientific community the state of the art in tissue adhesive application tomeniscus repair. For the past year in particular, the journal has emphasized in its publication the clinical applications of biomaterials, especially their bedside success and failure.
I would like to thank Dr. Buma and his colleagues for kindly agreeing to offer a cohesive clinical and investigational account of their ongoing work in meniscus repair using tissue adhesives.
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