Flexor Tendon Lacerations

Continuing Education Activity

Flexor tendon injury is frequently seen in household accidents involving knives, glass, or mirror injuries, but also can be due to chainsaw injuries, crush injuries, mesiofacial degloving injuries, bite injuries, sheet metal injuries, scissors injuries, or ceramic chip injuries. This activity outlines the evaluation and surgical treatment of flexor tendon lacerations and highlights the role of the interprofessional team in evaluating, treating and improving care for patients with this condition.


  • Identify the etiology of flexor tendon lacerations.
  • Explain how to evaluate flexor tendon lacerations.
  • List the treatment and management options available for flexor tendon lacerations.
  • Describe how an optimally functioning interprofessional team would coordinate care to enhance outcomes for patients with flexor tendon lacerations.


The flexor tendon repair is one of the most demanding techniques because sometimes the results are not ideal. This article reviews the configuration to perform a tenorrhaphy. There is no consensus for its use. At present, there are many variants and many threads and materials that can be used; however, there is little variety of elements to reinsert an avulsed tendon.

Numerous works that study the anatomy, physiology, nutrition of the tendon and its biomechanics have contributed to the fact that the technique is to debug and perfect. The advent of new postoperative protocols has made functional results improve, drawing on the trinomial surgeon-physical therapist-patient relationship.


Flexor tendon injury is frequently seen in household accidents that occur with knife, glass or mirror injuries, but also with a chainsaw injury, crush injury, damage by mesiofacial degloving injury and bite, sheet metal, mower knives, scissors or ceramic chips.


There are no differences between gender or age.


Morphology [1]

Seventy percent of flexor tendon is composed of chains of tropocollagen (peptides in triple helix), type-I collagen, and fibroblasts mature (tenocytes).

The extension of the same is covered by the endotendon.

In hand, the tendon is covered by a visceral and parietal adventitia called paratendon closely related to the synovial fluid lubricant.

The pulleys not only fulfill the function known to avoid the rope of arc but also provide a sliding surface and protection to the tendon.

Nutrition [1]

Nutrition depends on 2 systems: parietal and the system link.

The binding is a structure of nutrition that is included in the mesotendon, and it is part of the intrinsic contribution to tendon healing. There are long and short links.

If you study the flexor tendon through a cut end, there is evidence that the vast majority of the vessels are located in the dorsal (deep).

The paratendon parietal works as a mechanism of dissemination or a passive system of entry and exit of nutrients.

Tendon Healing Physiology [1]

Professionals believe that both the intrinsic and the extrinsic factors collaborate with scarring of the tendon. The first 48 to 72 hours correspond to a period of inflammation, then evolve to the fibroblastic phase, or collagen, that extends up to the fourth week. The final phase of remodeling lasts up to week 16. During the first phase, the force is supported only by the suture. Therefore, care during this period is critical to prevent a failure in the repair. After this first phase, the resistance increases rapidly during the fibroblastic phase. When considering predominances, there will be excessive adhesions between the tendon and the neighboring tissues if the extrinsic scarring prevails on the intrinsic one.

History and Physical

Examination of the flexor digitorum superficialis (FDS) tendon, as distinct from the flexor digitorum profundus (FDP) tendon, is performed. Active flexion is evaluated for each digit separately and, if present, indicates intact fibers of the FDS inserting into the middle phalanx. Practitioners evaluate the FDP tendon with DIP joint active flexion. 

The FDP tendon is divided into 5 anatomic zones. Zone I lies distal to the insertion of the FDS tendon. A synovial tissue covers the distal aspect of zone III, and the proximal aspect of the A1 pulley is the entrance to the flexor sheath or zone II of the flexor tendon. Zone III represents the origin of the lumbricals from the FDP tendon. Zone IV describes the flexor tendons within the carpal tunnel, and zone V extends from the muscle-tendon junction to the proximal aspect of the carpal tunnel. 


The most widely used method to evaluate the functional results is the formula of Strickland and Glogovac. This formula measures the active mobility of the joints IFP and IFD, subtracting the deficit of the extension if it exists. Buck-Gramcko system is used to evaluate the functional results of thumbs.[2] 

Treatment / Management

Considerations for the Flexor Tendon Suture [1]

Strickland numbers a list of the aspects that are considered essential to achieve an ideal primary repair of the flexor tendon:

  • Sutures easily located in the tendon
  • Properly secure the knots of the suture
  • Ensure that the ends of the tendon to join in a non-bulky
  • Have minimum space on the site of the repair
  • Get minimum interference with the vascularization of the tendon
  • Achieve a sufficient strength in the repair to allow the application of a voltage of early movement

Surgical Technique for Repairing the Deep Flexor Fingers in Zone II [1]

In brachial plexus anesthesia, local or general anesthesia can be used, with the patient in the supine position and with a pneumatic tourniquet. The enlargement of the wound can be done through a Bruner approach on one side. Then, the procedure continues, with the help of magnification, to identify both neurovascular bundles. Then, the surgeon opens the flexor sheath to correctly identify the magnitude of the lesion and the ends of the tendon. It is repaired between the windows that let the pulleys cruciform after His section, pulleys, A1, A3 and A5 or minimal partial openings of the pulleys A2 and A4.

The technique consists of a central simple point double-stranded that enters and leaves the ends of the tendon, and it is closed on its side. The material used is Nylon 4-0; repair is completed with additional horizontal points at the ends of the tendon with Nylon 6-0. In the case that both the FDP and the nerve collateral are cut off, both are repaired.

After the corresponding washing and hemostasis, the synthesis of the skin is carried out with Nylon 5-0.

Surgical Technique for Deep Flexor Tendon Insertion

The anesthesia, the approach, and the identification of the ends of the tendon are made in the same way mentioned above for the repair in zone II.

The opening of the sheath between the pulleys C3 and A5 is made. In injuries in zone II distal to the pulley A4 without distal tendon or avulsion, the surgeon may perform a pull-out or use an anchor, then reinsert the avulsed tendon in His bed, trying to place it in the hole previously wrought. If the distal stump is longer than 1 centimeter (if it was sectioned and not avulsed), it can be carried out an end-to-end suture with the 4 strands.

Finally, the skin is profusely washing and closed.

Surgical Technique of Tenorrhaphy in Zone III 

There are no contrasts in regards to the repair in zone II or in the postoperative treatment.


The prognosis is excellent, and good results for the long fingers obtained with this technique revolve around 90% to 95%. The worst outcome is related to non-compliance with the postoperative protocol on the part of the patient. Postoperative compliance is the determining factor in the favorable evolution after surgery and in cases with complications such as skin necrosis that delayed rehabilitation. The best results are obtained in young patients. There is no relationship between the area of insult in the FLP and the functional results obtained.

The active participation of a team of therapists contributes significantly to improving outcomes through a strict custom and postoperative protocol that shows a difference in the functionality of the fingers operated on in the patients who complied with the protocol and those who did not. This leads patients to return more quickly to normal tasks.

Enhancing Healthcare Team Outcomes

An interprofessional team that provides an integrated approach to postoperative care can help achieve the best possible outcomes.

Collaboration and communication are key elements for a good outcome. The interprofessional care provided to the patient must use an integrated care pathway combined with an evidence-based approach to planning and evaluation of all joint activities. 

he active participation of a team of therapists contributes significantly to improving outcomes through a strict custom and postoperative protocol that shows a difference in the functionality of the fingers operated on in the patients who complied with the protocol and those who did not. This leads patients to return more quickly to normal tasks.

(Click Image to Enlarge)
Flexor Tendon Laceration
Laceration of skin and flexor tendons of toes 3-5.
Flexor Tendon Laceration Laceration of skin and flexor tendons of toes 3-5.
Contributed by Mark A. Dreyer, DPM, FACFAS
Article Details

Article Author

Juan Carlos Caruso

Article Editor:

Juan Patiño


8/29/2020 7:14:59 PM



Strickland JW, Development of flexor tendon surgery: twenty-five years of progress. The Journal of hand surgery. 2000 Mar     [PubMed PMID: 10722813]


Strickland JW,Glogovac SV, Digital function following flexor tendon repair in Zone II: A comparison of immobilization and controlled passive motion techniques. The Journal of hand surgery. 1980 Nov     [PubMed PMID: 7430595]