Tendon healing: an overview of physiology, biology, and pathology of tendon healing and systematic review of state of the art in tendon bioengineering.
OBJECTIVE
Tendon injuries vary from acute rupture to chronic tendinopathy. For an optimal treatment of either condition, a profound knowledge is essential. Therefore, this article shall give an overview of physiology, biology, and pathology of tendon healing and state of the art in tendon bioengineering.


METHODS
For a preferably comprehensive survey, the current literature listed in PubMed and published in English peer-reviewed journals (March 2013) was systematically reviewed for tendon healing and tendon bioengineering including cytokine modulation, autologous sources of growth factors, biomaterials, gene therapy, and cell-based therapy. No differentiation was made between clinical and preclinical in vitro investigations.


RESULTS
Tendon healing happens in certain stadiums of inflammation, formation, and remodelling. An additional process of "collagen recycling" close to the healing site has been described recently. With increasing comprehension of physiology and pathology of tendon healing, several promising approaches in tendon bioengineering using growth factors, biomaterials, gene therapy, or cell-based therapy are described. However, only some of these are already used routinely in clinics.


CONCLUSIONS
Strong and resistant tendons are crucial for a healthy musculoskeletal system. The new approaches in tendon bioengineering are promising to aid physiological tendon healing and thus resulting in a stronger and more resistant tendon after injury. The growing knowledge in this field will need to be further taken into clinical studies so that especially those patients with prolonged courses, revision surgery, or chronic tendinopathy and high-demanding patients, i.e., professional athletes would benefit.


METHODS
II.
Department of Orthopedic Surgery, University Hospital Basel, Spitalstrasse 21, 4031, Basel, Switzerland, muellerse@uhbs.ch.
Sebastian A
SA
Müller
Atanas
A
Todorov
Patricia E
PE
Heisterbach
Ivan
I
Martin
Martin
M
Majewski
D001672:Biocompatible Materials / Q000627:therapeutic use; D057005:Bioengineering; D064987:Cell- and Tissue-Based Therapy; D003094:Collagen / Q000502:physiology; D016207:Cytokines / Q000502:physiology; D015316:Genetic Therapy; D006801:Humans; D007249:Inflammation / Q000503:physiopathology; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology; D012421:Rupture / Q000473:pathology; D052256:Tendinopathy / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D013708:Tendon Injuries / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy*; D014945:Wound Healing / Q000502:physiology*
D001672:Biocompatible Materials; D016207:Cytokines; D036341:Intercellular Signaling Peptides and Proteins; D003094:Collagen