How Are Tendons Reattached? Surgical Procedures

Tendons are reattached by stitching the torn ends back together, anchoring them to bone, or sometimes both, depending on where the injury occurred and how badly the tissue is damaged. The specific procedure varies widely by location in the body: a torn rotator cuff in the shoulder calls for a different approach than a severed flexor tendon in the finger or a ruptured Achilles at the ankle. But the underlying goal is always the same: restore a strong, gliding connection between muscle and bone so the joint can move again.

Why Tendon Reattachment Is Harder Than It Sounds

Tendons connect two very different materials. On one end you have soft, flexible tissue, and on the other you have rigid bone. In a healthy body, the transition zone between them (called the enthesis) features gradual shifts in structure, composition, and stiffness that distribute stress evenly across the junction. When a tendon tears off bone and a surgeon reattaches it, that carefully graded transition does not grow back the same way. Healing typically produces scar tissue instead, which is mechanically inferior to the original.

1PubMed Central. The development and morphogenesis of the tendon-to-bone insertion – what development can teach us about healing

This mismatch is a major reason re-tears happen after surgical repair. It also explains why so much research focuses not just on stronger stitching methods but on ways to biologically improve the healing interface, from growth factors to synthetic scaffolds. The surgery itself is only half the battle; how the body heals around the repair determines the long-term result.

Suture Techniques for Joining Torn Tendon Ends

When a tendon ruptures in its midsection, the surgeon’s primary job is to bring the two frayed ends together and stitch them securely. Several well-known stitching patterns exist, each threading suture material through the tendon in a slightly different geometry. The most commonly referenced are the Kessler, the Bunnell, and the Krackow techniques, along with numerous modifications of each. The original Kessler grasping technique, described in 1969, has been modified so many times over the decades that what surgeons now call a “modified Kessler” looks quite different from the original.

You might assume one technique is clearly stronger than the rest, but laboratory testing tells a more nuanced story. A cadaver study comparing Krackow, Bunnell, and Kessler repairs in Achilles tendons found no significant strength difference among them when each used a double suture weave.

2PubMed. The strength of achilles tendon repair: a comparison of three suture techniques in human cadaver tendons

A separate biomechanical comparison found that the Bunnell technique had advantages in mode of failure, while a minimally invasive configuration performed differently in elongation, suggesting that each technique has trade-offs depending on what the surgeon prioritizes.

3PubMed Central. Biomechanical comparison of tendon repair techniques: Bunnell suture leads in mode of failure and minimally invasive configuration in elongation

The choice of suture material matters too. One study tested the Bunnell, modified Kessler, and Tsuge techniques using both polyester and polydioxanone sutures, and the results shifted depending on the combination. The Tsuge technique paired with polyester suture produced the highest force resistance in certain measures, while the Bunnell technique was superior in stiffness with polyester and gave the best grip strength with polydioxanone suture.

4PubMed Central. Biomechanical comparison of Bunnell, modified Kessler, and Tsuge tendon repair techniques using two suture types

In practice, surgeons choose the technique and suture combination that best fits the tendon they are repairing, the patient’s anatomy, and their own training. There is no single “best” stitch for every situation.

Anchoring Tendons Back to Bone

Not all tendon injuries are midsubstance tears where two ends need stitching. In many common injuries, the tendon pulls away from the bone itself. A torn rotator cuff or a ruptured distal biceps tendon are classic examples. Here, the surgeon must fix the tendon’s end directly onto the bone surface, and that requires hardware.

The workhorse devices are suture anchors, small implants drilled or screwed into bone. Sutures are pre-threaded through the anchor, and the surgeon passes those sutures through the tendon, then ties or cinches them down to press the tendon firmly against the bone. Anchors come in two broad categories: traditional “hard body” anchors made of metal or a bioabsorbable polymer, and newer “all-suture” anchors that are mostly woven suture material and much smaller. Biomechanical testing has consistently shown that all-suture anchors hold up comparably to traditional anchors. One study found no significant difference in pullout strength or displacement between the two types.

5PubMed Central. Pullout strength of all suture anchors in the repair of rotator cuff tears: a biomechanical study

A more detailed analysis of several all-suture anchor designs showed that triple-loaded anchors (carrying three suture strands) held roughly twice the force of single-loaded ones, while none of the tested anchors shifted more than a few millimeters during repeated loading cycles.

6PubMed. All-Suture Anchors: Biomechanical Analysis of Pullout Strength, Displacement, and Failure Mode

All-suture anchors have a practical advantage beyond strength: their smaller drill holes preserve more bone, which matters if a revision surgery is ever needed.

For certain repairs, surgeons use an interference screw instead of or alongside a suture anchor. In distal biceps tendon reattachment, for instance, the tendon is threaded into a drill hole in the radius bone and locked in place with a screw that wedges the tendon against the tunnel wall. A hybrid technique adding a cortical button on the far side of the bone has been tested, but it did not significantly improve failure strength beyond what the interference screw alone provided.

7PubMed. Biomechanical comparison of interference screw and cortical button with screw hybrid technique for distal biceps brachii tendon repair

Single-Row Versus Double-Row Fixation in the Shoulder

Rotator cuff repair is one of the most frequently performed tendon reattachment surgeries, and how many rows of anchors the surgeon uses has been a major topic of debate. In a single-row repair, one line of anchors is placed along the edge of the bone footprint. In a double-row repair, a second row of anchors is added laterally, creating a broader area of contact between tendon and bone.

Biomechanical studies consistently favor the double-row approach in the lab. One study found that adding a medial row of anchors increased the stiffness of the repair by about 46% and the ultimate failure load by roughly 48%, while gap formation under cyclic loading was cut to less than half.

8PubMed. Biomechanical comparison of a single-row versus double-row suture anchor technique for rotator cuff repair

Another biomechanical evaluation confirmed that double-row fixation achieved significantly higher ultimate tensile load than all tested single-row configurations.

9Journal of Bone and Joint Surgery. Biomechanical Evaluation of Arthroscopic Rotator Cuff Repairs: Double-Row Compared with Single-Row Fixation

A newer variation uses three all-suture anchors instead of two hard-body anchors and has shown improved contact pressure between tendon and bone without sacrificing cyclic displacement, stiffness, or ultimate load.

10PubMed Central. Three Medial All Suture Anchors Improves Contact Force Compared to Two Hard Body Anchors in a Biomechanical Two-Tendon Rotator Cuff Tear Model

Whether the lab-measured advantages of double-row repair translate into better patient outcomes is less clear-cut, and the debate continues. But for larger tears, many surgeons lean toward double-row or “suture bridge” constructs to maximize the tendon’s footprint coverage on bone.

Open Surgery Versus Arthroscopic and Percutaneous Approaches

Tendons can be reattached through a traditional open incision, through small keyhole incisions using a camera (arthroscopy), or through percutaneous techniques that use stab incisions and specialized instruments. Each approach has genuine trade-offs, and the evidence suggests the differences are smaller than you might expect when it comes to long-term outcomes.

For rotator cuff tears, a prospective randomized trial comparing open and arthroscopic repair found no significant difference in shoulder scores, subjective shoulder value, or re-tear rates at long-term follow-up. Both groups had a re-tear rate of about 30% on MRI.

11Journal of Shoulder and Elbow Surgery / JSES International. No difference in long-term outcome between open and arthroscopic rotator cuff repair: a prospective, randomized study

A second prospective trial confirmed similar results, with no statistical difference in Constant scores or re-tear rates between the two approaches.

12PubMed. No difference in outcome for open versus arthroscopic rotator cuff repair: a prospective comparative trial

That said, arthroscopic repair does tend to cause less tissue disruption, which can mean shorter recovery times and lower infection rates, advantages that may matter more in patients who already face compromised healing.

13PubMed Central. Outcomes of Rotator Cuff Repair: Open vs. Arthroscopic Approaches in Patients with Diabetes or Hyperlipidemia

The Achilles tendon follows a similar pattern. Percutaneous repair, done through small stab incisions, has been shown to be a safe and reliable method with fewer wound complications compared to open techniques.

14PubMed Central. Percutaneous cruciate repair of ruptured Achilles tendon

A direct comparison found no significant difference in healing time, return to activity, or patient satisfaction between open and percutaneous Achilles repairs, with both groups achieving full weight bearing by the eighth week. The percutaneous group did, predictably, end up with a better-looking scar.

15PubMed. Percutaneous versus open repair of acute Achilles tendon ruptures

Open surgery retains clear advantages when the damage is extensive, when the surgeon needs direct visualization to navigate around nerves or other delicate structures, or when the tendon has retracted so far that it cannot be retrieved through small incisions. The choice is rarely ideological; it depends on the specific tear, the tendon involved, and the patient’s overall health.

What Happens in the Hand

Hand tendon repairs deserve their own discussion because the anatomy creates unique challenges. Flexor tendons in the fingers run through tight tunnels called tendon sheaths, held in place by a series of pulleys. Repairing a tendon cut inside these tunnels (especially the notoriously difficult “zone II” between the palm and the fingertip) means the surgeon must restore the tendon’s ability to glide smoothly without sticking to the surrounding sheath or pulleys.

After zone II flexor tendon repair, adhesions between the repaired tendon and the sheath are one of the most common complications, leading to stiffness and loss of finger motion.

16PubMed. Current trends in the prevention of adhesions after zone 2 flexor tendon repair

If the pulleys themselves are damaged during the injury, the surgeon may need to reconstruct them. Cadaver testing has shown that pulley reconstruction after zone II repair can partially restore gliding mechanics, though it does allow slightly more “bowstringing” (the tendon pulling away from the bone like a bowstring) compared to the intact state.

17PubMed Central. The Effect of Pulley Reconstruction on Maximum Flexion, Bowstringing, and Gliding Coefficient in the Setting of Zone II Repair of FDS and FDP: a Cadaveric Investigation

The healing process for tendons generally follows three overlapping phases: inflammation, cell proliferation, and tissue remodeling, with time frames that vary by the specific tendon involved.

18PubMed Central. Tendon: Principles of Healing and Repair

In the hand, the guiding surgical principle has long been to provide the minimum protective immobilization needed to protect the repair, then introduce therapy as early as safely possible to prevent those adhesions from locking up the finger.

Why Moving Early After Surgery Matters

One of the most important advances in tendon surgery over the past few decades has not been a new stitch or implant; it has been the shift toward early controlled motion after repair. Keeping a repaired tendon completely still for weeks might sound protective, but immobilization encourages scar tissue to form between the tendon and its surroundings, which can glue everything together.

Animal research on flexor tendons showed that tendons repaired with a robust four-strand technique and then actively mobilized were significantly stronger than immobilized tendons across the entire 42-day study period. The mobilized tendons also healed without the extrinsic adhesions and large calluses seen in the immobilized group.

19PubMed. Comparison of postoperative early active mobilization and immobilization in vivo utilising a four-strand flexor tendon repair

Clinical studies in humans back this up. A trial of extensor tendon repairs found that patients assigned to early active motion had better total active motion and returned to work earlier, with these differences being statistically significant up to 12 weeks, though by six months the immobilization group had caught up.

20PubMed Central. Early active mobilisation versus immobilisation after extrinsic extensor tendon repair: A prospective randomised trial

A more recent comparison of early active mobilization versus immobilization for extensor tendons in zones 5 and 6 found significantly higher finger motion at discharge for the early-motion group, with no tendon ruptures reported.

21PubMed. Immobilization versus Early Active Mobilization after Zone 5-6 extensor tendon repair

The biological explanation fits the clinical picture: controlled mechanical loading after repair activates cell signaling pathways that promote collagen production and organized tissue remodeling, strengthening the repair from the inside.

22PubMed Central. Effects of Mechanical Loading on the Structure and Function of the Achilles Tendon: From Homeostatic Adaptation to Pathological Degeneration

Without that mechanical stimulus, the new collagen fibers tend to form in disorganized patterns, producing weaker, stiffer scar.

23PubMed Central. The role of mechanical loading in tendon development, maintenance, injury, and repair

Early motion is not the same as unrestricted use. Rehabilitation protocols are carefully dosed, typically starting with passive or lightly assisted movements and gradually increasing the load over weeks. The strength of the surgical repair has to be able to tolerate the motion protocol, which is why multi-strand suture techniques and strong anchor constructs matter so much.

Adhesions and How Surgeons Try to Prevent Them

Adhesions remain one of the biggest obstacles to a good result after tendon repair, particularly in the hand. The body’s inflammatory response to surgery deposits fibrous tissue not just at the repair site but between the tendon and surrounding structures. Once those adhesions mature, the tendon can no longer slide freely, and the patient ends up with a finger, hand, or ankle that is stiff despite a mechanically intact repair.

Peritendinous adhesion involves abnormal connective tissue overgrowth and excessive matrix deposition around the repaired tendon.

24Computational and Structural Biotechnology Journal. Peritendinous adhesion: Therapeutic targets and progress of drug therapy

Researchers have explored multiple strategies to prevent this, ranging from physical barrier membranes (made from collagen, chitosan, or synthetic polymers) placed around the repair, to pharmacological agents like anti-inflammatory drugs and even chemotherapy compounds like 5-fluorouracil applied locally. Preclinical studies show significant adhesion reduction with some of these approaches, but inconsistent degradation rates, potential toxicity, and a shortage of human clinical data mean most have not yet become standard practice.

25PubMed Central. Anti-adhesive agents in tendon repair: mechanisms, preclinical evidence, clinical challenges, and future perspectives-a narrative review

For now, the most reliable anti-adhesion strategy remains the combination of a meticulous surgical technique that minimizes tissue trauma and an early controlled motion protocol that keeps the tendon gliding before adhesions can set in.

Grafts and Reconstruction for Irreparable Tears

Sometimes a tendon is too damaged, retracted, or degenerated to be directly repaired. In those cases, a surgeon may bridge the gap with a graft, a strip of tendon tissue taken from elsewhere in the patient’s own body (an autograft) or from a donor (an allograft). Common autograft sources include the palmaris longus tendon in the forearm or a strip of hamstring tendon. Allografts are typically freeze-dried or chemically processed before use.

An animal study comparing live autografts and freeze-dried allografts for flexor tendon reconstruction found an interesting result: there was no significant difference in maximum tensile force or stiffness between the two graft types over time. Autografts produced more extensive remodeling and scarring around the entire graft body, while allograft scarring concentrated mostly near the junctions where it was sewn in.

26PubMed Central. Adhesions in a murine flexor tendon graft model: autograft versus allograft reconstruction

The finding that the biomechanical advantage of live autograft over devitalized allograft was minimal challenges the longstanding assumption that “your own tissue is always better.” The reality is that both graft types come with trade-offs: autografts require a second surgical site and may create scarring problems, while allografts carry a small risk of immune response and disease transmission.

Scaffolds, Biologics, and the Future of Repair

Tissue engineering is actively trying to close the gap between what a surgeon can build in the operating room and what the body originally grew. Scaffolds, sheets or meshes of biological or synthetic material sutured over the repair site, are the most common strategy investigated so far.

27PubMed Central. Scaffolds in tendon tissue engineering

These scaffolds serve as temporary mechanical reinforcement and as a lattice for the patient’s own cells to grow into. Results have been mixed, though progress continues.

28PubMed Central. Scaffolds for tendon and ligament repair and regeneration

A newer generation of hybrid scaffolds combines synthetic polymers for strength with biological materials for cell compatibility. One example woven from collagen and poly(lactic acid) yarns achieved tensile strength well above what would be needed for normal tendon function, and the collagen component significantly improved tendon cell proliferation on the scaffold surface.

29PubMed Central. A collagen/PLA hybrid scaffold supports tendon-derived cell growth for tendon repair and regeneration

Platelet-rich plasma (PRP) is another biologic augmentation that has generated intense interest and equally intense debate. PRP is made by concentrating the patient’s own blood platelets, which release growth factors involved in tissue healing. It is widely used in orthopedic and sports-medicine settings. Basic science work generally supports its potential, but clinical results have been inconsistent, with outcomes varying depending on the specific injury, the PRP preparation method, and patient factors.

30PubMed Central. Can PRP effectively treat injured tendons? 31PubMed Central. Augmenting tendon and ligament repair with platelet-rich plasma (PRP)

The evidence is not yet strong enough to declare PRP a standard part of tendon repair, but it is not strong enough to dismiss it either. Researchers argue that better understanding of exactly how PRP works at the cellular level will lead to more targeted, effective use.

Tendon Surgery in Children

Pediatric tendon and ligament surgery follows the same basic principles of reattachment but adds a critical constraint: children have growth plates. Any surgical technique that drills across a growth plate risks disrupting normal bone growth, potentially causing a limb-length discrepancy or angular deformity. For that reason, techniques used in adults often cannot be applied to children without modification.

This concern is especially prominent in anterior cruciate ligament (ACL) reconstruction, where a tendon graft is typically threaded through tunnels drilled in the thighbone and shinbone, directly crossing the growth plates. Physeal-sparing techniques have been developed that route the graft entirely within the epiphysis (the end of the bone, above or below the growth plate) to avoid crossing it. One study evaluating 57 pediatric patients who underwent physeal-sparing ACL reconstruction using patellar tendon found the technique to be safe, with no significant growth disturbance and outcomes that were actually better than those typically seen in adults.

32PubMed. Physeal-sparing reconstruction of anterior cruciate ligament tears in children: results of 57 cases using patellar tendon

Alternative graft choices, such as quadriceps tendon autograft used with an all-epiphyseal technique, further reduce the risk of growth-plate injury.

33PubMed Central. Physeal-Sparing Anterior Cruciate Ligament Reconstruction for Skeletally Immature Patients: All-Epiphyseal Technique Using Quadricep Tendon Autograft

Beyond ACL reconstruction, the general principle holds for any tendon surgery in a growing child: the surgeon must balance achieving a secure repair against the risk of damaging growth cartilage, which often means accepting a slightly less rigid fixation method than would be used in an adult. The good news is that children’s tissues heal faster and more robustly, which helps compensate.

Anesthesia Innovations for Tendon Repair

An evolving area in tendon surgery is the way procedures are performed under local rather than general anesthesia. The “Wide Awake Local Anesthesia No Tourniquet” (WALANT) technique, now well established in hand surgery, uses an injection of local anesthetic with epinephrine to both numb the area and control bleeding, eliminating the need for a tourniquet or sedation. This approach allows the patient to actively move the repaired tendon on the operating table so the surgeon can check that the repair glides properly before closing. A preliminary study exploring WALANT combined with a nerve block for Achilles tendon repair found the combination was effective in over 90% of cases, with appropriate hemostasis in all patients and no need for a pneumatic tourniquet.

The ability to test a tendon repair in real time, with the patient awake and moving, is a meaningful step forward. It lets the surgeon confirm adequate strength and smooth gliding before the patient leaves the operating room, rather than discovering a problem weeks later when healing is already underway.