An open incision provides enough room for the surgeon to prepare a tissue for repairing to the tissue or sewing the tissue together, nonabsorbable sutures make sure that the repair is as strong as possible. A small screw/anchor is used to reattach the tendon back to the bone if the it has been ruptured completely. Surgeons often use a strong nylon or polyester material to bring the edges of your torn tendon together.
Muscle related damage the surgeon often use a strong nylon or polyester material to bring the edges of your torn muscle together. They use a locking-loop or three-loop pulley pattern to prevent the muscle tissue from gapping. This also provides the muscle with the 'tension' needed to ensure the muscle heals with stronger fibers. (source: US National of Library of Medicine - https://www.ncbi.nlm.nih.gov/pubmed/2697063)
An open procedure with precise suturing improves overall strength of your tendon / muscle during the recovery process, making it less likely to re-rupture in the future.
Debulking or Debridement of the Soft Tissue
This surgical technique is done during open tendon surgery. To perform a debulking or debridement the surgeon will cut away any damaged/inflamed tissue and scrape down any calcium deposits (bone spurs) that have grown on bone. Scar tissue may be removed from the tendon fibers, tendon sheath surrounding the tissue or from both surfaces.
Debulking or debridement of the tendon or muscle is used as a last resort, if all methods of conservative therapy have been exhausted, in chronic conditions.