A cut flexor tendon is a surgical emergency — and how it's repaired determines how well your finger ever moves again. Dr. Graham performs a 6-strand non-absorbable repair under local anesthesia, allowing real-time feedback on every stitch. In his experience, this approach produces strong, slim repairs that move early — and patients have less stiffness and faster return to function as a result.
Any deep palm-side cut with altered finger motion should be evaluated urgently — even if the wound looks small. Flexor tendons sit just beneath the skin in some zones.
Understanding the Injury
The flexor tendons are the cables that run along the palm side of your fingers and thumb, connecting the forearm muscles to the fingertip bones. When you make a fist or grip an object, it is these tendons that do the work. Each finger has two — the flexor digitorum superficialis (FDS), which bends the middle joint, and the flexor digitorum profundus (FDP), which bends the tip joint. The FDP also provides grip strength.
A laceration — from glass, a kitchen knife, a box cutter, sheet metal, a saw — can sever one or both tendons at any point along their course. The tendon ends spring apart immediately after injury, and the longer before repair, the more they retract and the more difficult retrieval becomes. What remains is a finger that will not flex at one or both joints, resting in an unnaturally straight position compared to its neighbors.
Flexor tendon injuries are also frequently accompanied by digital nerve injuries, because the nerves run immediately alongside the tendons through the finger. A cut tendon with associated numbness almost always means the nerve was also divided, and Dr. Graham will repair it at the same operation.
In Dr. Graham's experience, patients are often surprised by how small the wound looks relative to how significant the injury is. A half-inch glass cut on the palm side of the finger can completely sever both tendons. Every palm-side hand laceration with altered finger motion deserves urgent surgical evaluation.
Both the FDP and FDS tendons run through a tight fibro-osseous sheath reinforced by the critical A2 and A4 pulleys. Any repair in this space must be strong enough to move yet slim enough to glide through without catching.
When the tendon is cut, both ends spring away from the laceration site. The proximal end — still attached to the muscle — retracts further with every attempt to grip or move the finger, making timely repair essential.
Recognizing a Flexor Tendon Injury
The signs of a flexor tendon laceration are often obvious — but not always. Small wounds can hide complete tendon divisions.
The most telling sign. If the FDP is cut, the fingertip will not bend. If the FDS is cut, the middle joint won't flex. If both are severed, the finger lies completely flat — unable to curl toward the palm at all — while adjacent fingers close normally.
A normal hand at rest has fingers in a gentle cascade — slightly more curled from index to pinky. A finger with a cut flexor tendon breaks that cascade, resting unnaturally straight. This asymmetry is often visible at a glance and is a reliable clinical sign.
Glass, kitchen knives, box cutters, utility blades, power saws, and sheet metal edges are the most common culprits. Any laceration on the palm side of the hand or finger — even a small one — can divide the tendon completely. The wound size does not predict the severity of the injury underneath.
Even if the finger appears to move, grip strength may be significantly reduced with a partial tendon laceration. Partial tears are painful, unstable, and at high risk for progressing to complete rupture with continued use. A partially cut tendon still requires surgical repair.
Numbness or altered sensation on one or both sides of a finger after a laceration means the digital nerve was likely also divided. Dr. Graham will repair both the tendon and the nerve at the same surgery. Numbness does not make the injury less urgent — it makes it more complex.
Flexor tendon ends retract after injury. Every hour matters — both for the tendon anatomy and for the potential presence of an open wound that requires washout. Any palm-side hand laceration with loss of finger flexion or any deep hand injury should be evaluated the same day. Call (904) 241-1204 or go to the nearest emergency department for initial wound care, then follow up with Dr. Graham as soon as possible.
Injury Location
The hand is divided into five flexor tendon zones. The zone of injury is the single most important factor in predicting surgical difficulty and outcome. Zone 2 is where the stakes are highest.
Zone 2 runs from the base of the finger to the middle of the middle phalanx — a narrow fibro-osseous tunnel where both the FDP and FDS travel together, held tightly against bone by the A2 and A4 pulleys. Historically called "no man's land" because early results were so poor, it remains the most technically demanding zone for flexor tendon repair.
The challenge is geometric: two tendons must be repaired inside a tunnel that barely has room for one. The repair must be strong enough to withstand early active motion, smooth enough to glide without catching on the pulleys, and slim enough that the combined bulk of both tendons — plus suture — can still move freely. A repair that is too bulky will stall at the A2 or A4 pulley, and a pulley that is released too aggressively will allow bowstringing.
Zone 1 involves only the FDP tendon, distal to where the FDS has already inserted on the middle phalanx. Repairs here are technically more straightforward — only one tendon, and the pulleys are less constraining. The "jersey finger" avulsion injury, where the FDP pulls off the distal phalanx during a gripping force, occurs in Zone 1. Repair involves reinserting the tendon to bone.
Zone 3 lacerations occur in the palm itself, where the tendons emerge from the carpal tunnel and lumbrical muscles originate from the FDP. The tendon sheath is less constraining here, and both tendons can typically be repaired without the same pulley management concerns. Outcomes are generally better than Zone 2.
Zone 4 injuries occur within the carpal tunnel; Zone 5 in the forearm proximal to the wrist crease. Multiple tendons are often injured simultaneously with high-energy mechanisms. Median and ulnar nerve injuries are common at this level and are repaired concurrently. Technical access is easier, but the number of structures involved makes these cases complex in a different way.
Surgical Treatment
Every element of Dr. Graham's technique — from suture choice to anesthesia to post-operative protocol — is designed around one goal: a repair that moves well from day one.
Dr. Graham performs flexor tendon repairs under local anesthesia (WALANT — wide-awake local anesthesia, no tourniquet). While this is most commonly associated with carpal tunnel and trigger finger in-office procedures, Dr. Graham applies the same principle to tendon repairs in the operating room — and it changes what he can see and do.
With the patient awake and able to follow commands, Dr. Graham can ask them to actively flex the finger at any point during the repair. This tells him whether the repair glides smoothly through the pulley system, whether the suture construct is creating bulk that catches, and precisely which pulleys require venting and how far. No tourniquet means better visualization. A cooperative patient means intraoperative testing.
This real-time assessment is also how he determines whether to repair the FDS. If the patient flexes and both tendons glide cleanly, he repairs both. If the FDS repair creates a bulk problem that he can see catching on the pulley, he leaves it. That decision is made based on direct observation — not a predetermined protocol.
The core repair uses six strands of non-absorbable suture crossing the laceration site. Six-strand repairs are meaningfully stronger than 2- or 4-strand constructs — the number of strands directly correlates with resistance to gapping and rupture under active loading. This is what allows early motion without the repair coming apart.
An epitendinous suture — a running stitch placed around the circumference of the tendon at the repair site — smooths the surface, adds 10–20% additional strength, and reduces the gap between tendon ends. In Dr. Graham's experience, the epitendinous suture is not optional; it is part of what makes the repair glide.
Dr. Graham attempts to repair both the FDP and FDS in most Zone 2 cases. However, the FDS repair is confirmed — not assumed — based on what he sees when the patient flexes intraoperatively.
If both repairs glide cleanly through the sheath, both are left. If the FDS creates bulk that catches at the A2 or A4 pulley, it is excised. Forcing a FDS repair that cannot move defeats the purpose of the operation.
This is one of the clearest examples of why WALANT matters for this procedure: the question of whether to repair the FDS is answered definitively in the operating room, by the patient's own tendon, under their own power.
Local anesthetic is injected into the hand and finger. No tourniquet, no general anesthesia, no sedation required — though sedation is available for patients who strongly prefer it. The patient is awake, comfortable, and able to follow commands. This is the same anesthetic approach used for in-office carpal tunnel and trigger finger procedures, applied here in the OR for its intraoperative assessment value.
The laceration is extended using Brunner zigzag incisions to preserve skin vascularity while allowing wide exposure. Both tendon ends are identified and retrieved — the proximal end, which has retracted under muscle tension, is milked back distally. Both ends are prepared with the core suture pre-placed before the repair is completed. Adjacent neurovascular structures are identified and protected.
Six strands of non-absorbable suture are placed across the repair site in a configuration that distributes tensile load evenly. The knots are buried between the tendon ends to minimize surface irregularity. Once the core repair is complete, a circumferential epitendinous suture is run around the repair site, smoothing the surface and adding additional structural integrity.
With the repair complete, Dr. Graham asks the patient to actively flex the finger. He directly observes how the repair travels through the pulley system. If it glides cleanly, the repair is complete. If it catches, he identifies the offending pulley and vents it precisely — only as far as needed, no further. In Dr. Graham's experience, this step is where bowstringing is prevented: by controlled, targeted pulley release guided by what the repair actually shows him, rather than by a predetermined formula.
The FDS repair is confirmed or revised based on glide testing. If the FDS creates a bulk problem at the pulley, it is left. If a digital nerve was divided, it is repaired under loupe magnification at this time — with meticulous alignment of fascicular groups to optimize sensory recovery. Nerve repair adds operative time but is always performed when indicated, at the same setting as the tendon repair.
Wounds are closed in layers. A light dressing is applied. In Dr. Graham's experience, his 6-strand repairs are strong enough that rigid bracing is frequently not required. Many patients are instructed in early active motion — carefully guided — without a dorsal blocking splint. This is not the standard protocol, and it reflects the strength of the repair and confidence from consistent outcomes with this approach. Hand therapy begins promptly.
Recovery
The enemy of flexor tendon outcomes is adhesion — scar tissue that forms around the repair and prevents the tendon from gliding. Early motion, guided by a skilled hand therapist, is the most powerful tool against it.
Dressing is kept clean and dry. In Dr. Graham's experience, many patients begin carefully guided active motion within the first few days — no rigid brace required. The hand is elevated to control swelling. Hand therapy referral is placed at or before discharge.
Formal hand therapy is the focus of this phase. Place-and-hold exercises, tendon gliding, and composite flexion work to prevent adhesion formation while respecting the repair's biological healing. Therapist and Dr. Graham communicate closely about progress. Sutures are removed at 10–14 days.
Resistance exercises are introduced gradually. Grip strength begins to return. Most patients can perform light activities of daily living with increasing ease. Scar management at the repair site becomes important — the epitendinous suture helps here, but silicone and massage add further benefit.
Most patients return to full light-duty function by 3 months and unrestricted use by 4 months. Manual labor and heavy gripping may require 4–6 months. Nerve recovery — if a nerve was also repaired — follows a slower timeline of 6–18 months depending on the length of the nerve gap and the distance to the target.
"Jean Ward described her experience as receiving an injection of humor along with expert surgical care — Dr. Graham called the day after surgery to check on her."
Jean Ward · Finger Surgery Patient · Verified Google Review ★ 5/5
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