Design Criterion – A set of rules and principles that set the standard of what must be achieved.

To create next level tendon repairs, we must identify the current problems and find a way to better them in the prototype.

1) Biodegradability

-Repairing the tissue would take time healing and matching the tangent stiffness up to 32% of failure force. The solution should also include biological composite scaffolds that are biodegradable. [23]

Fig.3

Chitosan Biopolymer at 10mm and increasing to the micron magnification level [31]

Additional Subfactors to Consider

  • Non-biodegradable material can be adverse to random sorts of people. Biodegradable insures safety to all no matter blood type,allergies, etc.  [31]
  • Scaffolds that can interact with the tendon and the surrounding biofluids without any harm to the system internally or externally.  [32]
  • Natural material from crustacean shells, removes ethical fears and concerns. [31]

2) Durability

As the tendons are strong and need an aid that is just as strong to aid healing and be resistant to the body’s fluids without wearing or having capillary action issues, we can used a reinforced chitosans scaffold that is strong to help act as pro-tempore tendon to aid the main Achilles Tendon repair. 

Chitosan polysaccharide scaffolds have been studied and shown to have great usage in Tissue Engineering based on its great adhesive properties and low degradation rate.  [24]

  • Why focus on Durability?  
    • Traditional scaffolds fail upon hours of insertion from surgery [23]
    • Supportive scaffolds have poor resistance to biofluids. [23]
  • Benefits of stronger durability?  
    • Can help speed up regeneration time opposed to alternatives. [28]
    • Prevents infection chances as scaffolds act as a biological barrier.  [23]
  • Existing Solutions of these durable polymers 
    • Several variants of Collagen-polymers scaffolds exist with specific degradation times [27]
    • Chitosan Polysaccharide Research proves promising !
      • One of the most durable variants. [23]
      • Resistant to biofluids for an extended period time [28]
      • Temporarily restored functionality until Completed 
        • Ultrafine (thin fibers <1µm thick) Chitosan Polymer in situ acts as a mechanical tendon and can provide temporary locomotion  [28] 

Fig 4 (Left)

Collagen Polymer from the company Biotek AG that has similar and competitive properties as Chitosan scaffolds. [29]

Fig 5 (Right; A is the scaffold, B as microscopic fibers)

Chitosan Scaffold and magnification, a general image of the traditional non-animal-based scaffolds and its ultrafine fibers [28]

 

3) Minimally Invasive

Some cases of tendon repairs are done very invasively (if the situation granted makes this the best choice), however invasive surgery has been seen to have damaging after effects on the target area of skin that was manipulated, stretched, or changed during surgery.

Along with chances of infection to the tendons, and longer repair times being a health hazard and hassle to the patient and doctors involved. Minimally invasive tendon repairs can be done with specialized suture devices that lock into place of the target tendon and “invade” with the least skin tissue damage; however the same limitations and health risks still remain, but at a lower chance (considering the least possible invasion of tissue is applied here). [25]

Competitive Comparison to Invasive Surgery

  • Problems with Invasive
    • Damages skin of the target area 
    • Increased chances of infection post-operation
    • Regeneration time is too long 
      • Sub-optimal for Athletes or Middle Aged Men 
    • Reduced Function for months 
  • Go Minimal!  [23]
    • Less Damage and aftermath scarring
    • Less Chances of Infection
      • Less invasive and infection chances due to using microbiological and intercellular interactions rather hands-on contact with the tendons.
    • Regeneration time shortened [28,29]
      • Encourages regeneration with hiSPC (Stem Cells) 

Fig 5

MISD in action on tendon experimentation and effectiveness. Two (outer left, outer right) larger MISD tools are for stability. The two (inner wires) are the MISD mean to surgically insert and incise themselves into the target area of surgery, along with having the wire go through as a suture initiation. [23]