Fellowship-Trained Expertise in Tendon Surgery
Flexor tendon repair is one of the most technically demanding procedures in modern hand surgery. The flexor tendons are responsible for bending the fingers and thumb, enabling every daily task that requires grip and dexterity. When one or more tendons are injured, the ability to move the finger or thumb is lost. Because the tendons run inside narrow tendon sheaths beneath the skin, their repair must be precise to restore smooth motion.
Dr. Thomas Neustein, a board-certified and fellowship-trained orthopedic hand and upper extremity surgeon, performs advanced flexor tendon repair and reconstruction using meticulous microsurgical technique. He treats both acute and chronic tendon injuries, combining expert surgical care with individualized rehabilitation to restore motion, strength, and confidence for his patients.
Understanding Flexor and Extensor Tendons
The hand contains two primary groups of tendons: flexor tendons, which bend the fingers and thumb, and extensor tendons, which straighten them. Flexor tendons originate from muscles in the forearm that share a common muscle belly before dividing into long tendons that run through protective tunnels called tendon sheaths.
Each tendon passes through annular pulleys and the oblique pulley, which keep the tendon close to the bone and maintain mechanical efficiency. Within these tunnels, a synovial sheath surrounds the tendon, providing lubrication and minimizing friction during movement.
Because the tendons are tightly enclosed within the sheath system, any cut, rupture, or swelling can severely limit motion and cause stiffness.
Anatomy of the Flexor System
Every finger has two major flexor tendons: the flexor digitorum superficialis (FDS), which bends the middle phalanx at the PIP joint, and the flexor digitorum profundus (FDP), which bends the distal phalanx at the DIP joint and contributes to overall grip strength.
The flexor tendons glide under the flexor retinaculum and transverse carpal ligament at the wrist before entering the digital sheath. They connect muscles to the bones of the proximal phalanx, middle phalanx, and distal phalanx, allowing coordinated motion at the MCP joints, PIP joints, and DIP joints.
Because these tendons share close quarters with nerves and blood vessels—including the median nerve—flexor tendon injuries frequently occur alongside neurovascular injury or partial lacerations of nearby structures.
What Is a Flexor Tendon Injury
A flexor tendon injury occurs when the tendon is cut, torn, or ruptured, resulting in immediate loss of finger flexion. These injuries may be partial tendon injuries, where only part of the tendon fibers are damaged, or complete ruptures, where the tendon is fully severed.
Common causes include deep lacerations to the palm or fingers, crush trauma or avulsion from the distal end of the tendon, sports injuries and falls causing ruptured tendon fibers, rheumatoid arthritis, or overuse in individuals with increased wrist loading or repetitive gripping.
Because tendons retract after rupture, immediate evaluation is crucial for successful repair.
Symptoms of a Flexor Tendon Injury
Typical signs include inability to bend the affected finger or thumb, pain and swelling along the tendon sheath, numbness or tingling if the median nerve or digital nerves are affected, a visible gap in the tendon’s course, and loss of tension when attempting DIP flexion or composite flexion.
If the injury involves the ring finger or small finger, patients may notice particular weakness in grip and reduced flexion at the distal aspect of the finger.
Diagnosing a Tendon Injury
Diagnosis begins with a careful medical history and physical examination. Dr. Neustein evaluates the patient’s ability to flex each finger independently, assessing both active motion and passive movement at the MCP, PIP, and DIP joints. The exact location of the tendon rupture or laceration is mapped along the palmar surface.
Imaging studies such as ultrasound or MRI help confirm whether the tendon ends are intact, retracted, or trapped within the sheath. These studies also reveal associated fractures or neurovascular injuries that require simultaneous repair.
Zones of Flexor Tendon Injuries
Flexor tendon injuries are classified into zones, each representing a specific anatomic region from the fingertip to the forearm:
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Zone I: Distal to the FDS insertion; involves the FDP near the distal end of the tendon.
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Zone II: Extends from the distal palmar crease to the insertion of the FDS; historically called “no man’s land” due to difficulty in achieving smooth glide.
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Zone III: Located in the palm where both tendons run within the common sheath.
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Zone IV: Inside the carpal tunnel beneath the flexor retinaculum.
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Zone V: Proximal to the wrist, where multiple tendons share a common muscle belly.
Each zone requires a tailored surgical approach based on tendon type, pulley integrity, and proximity to neurovascular structures.
Immediate Surgical Repair
Flexor tendon repair should be performed as soon as possible after injury. Early surgery reduces scar formation and allows for direct tendon approximation before retraction occurs. Dr. Neustein’s surgical team performs immediate surgery for complete lacerations or ruptures to optimize outcomes and minimize stiffness.
Delaying repair can lead to tendon shortening, adhesion formation, or the need for complex staged reconstruction.
Flexor Tendon Repair Technique
The procedure is performed under magnification at an accredited surgery center using microsurgical instruments and fine suture strands.
The wound is extended for exposure, the cut or ruptured tendon ends are identified and cleaned, and a direct tendon repair (primary repair) is performed using multi-strand core sutures that cross the repair site for strength. Epitenon sutures smooth the surface of the repaired tendon and reduce friction within the flexor sheath. The tendon sheath and oblique pulley are reconstructed to maintain tendon gliding. The wound is irrigated, the skin is loosely closed, and a splint is applied.
This approach provides strong, smooth repairs with fewer adhesions and reliable tendon healing.
Managing Partial Lacerations and Complex Injuries
Partial tendon injuries are repaired if more than 50% of the tendon’s diameter is disrupted. Complete lacerations always require surgical repair. For combined injuries involving extensor tendons, bone fractures, or neurovascular damage, all structures are addressed in a single operation.
Careful attention to the tendon sheath and blood supply prevents ischemia at the distal aspect of the finger and promotes long-term functional recovery.
Reconstruction and Tendon Grafting
In chronic cases or failed primary repairs, flexor tendon reconstruction may be necessary. A tendon graft is used to bridge the gap between the proximal and distal ends. The palmaris longus or plantaris tendon is commonly harvested for grafting.
The graft passes through the original flexor sheath to maintain smooth motion. If the sheath is scarred or destroyed, staged reconstruction using the Hunter technique may be performed, where a silicone rod is temporarily placed to create a channel for the tendon graft.
Tendon Transfer and Secondary Procedures
When the native tendon cannot be repaired or reconstructed, a tendon transfer may restore motion. This involves redirecting a healthy functioning tendon to substitute for the damaged one. Transfers are often used for injuries involving the ring finger, small finger, or chronic ruptured tendons that cannot generate force.
Secondary procedures such as tenolysis (scar release) may be required to improve gliding after the initial repair heals.
Microsurgical Techniques and Blood Supply Preservation
Flexor tendon surgery demands preservation of the surrounding blood vessels and synovial sheath to ensure adequate healing. Dr. Neustein uses minimal dissection and microsurgical magnification to maintain blood flow and reduce scar tissue formation.
Preserving the tendon’s nutritional environment within the sheath supports faster healing and fewer complications.
Postoperative Splinting and Early Rehabilitation
After surgery, the hand is placed in a dorsal blocking splint that keeps the wrist slightly flexed and the MCP joints flexed to relax tension on the repaired tendons.
Rehabilitation begins within days under supervision of a certified hand therapist. The protocol includes passive flexion and active extension within the splint, gradual increase in motion at the MCP, PIP, and DIP joints, and avoidance of forceful grip to prevent gap formation.
Early controlled motion reduces adhesions and promotes smoother tendon gliding.
The Role of Hand Therapy and Early Active Motion
Hand therapy is an essential part of recovery. Under the guidance of a skilled hand therapist, patients perform gentle early active motion to stimulate healing and maintain tendon glide. Passive movement exercises help prevent stiffness, while gradual loading improves tendon strength.
Therapy also includes swelling control, scar management, and functional retraining for grasp, pinch, and fine motor tasks.
Healing Process and Timeline
Tendon healing progresses through three overlapping stages.
The inflammatory phase lasts about a week as inflammatory cells clear debris. The proliferation phase follows, when collagen formation strengthens the repair site. The remodeling phase continues over several weeks as fibers realign for smooth gliding and resistance to rupture.
Patients begin light activities around six weeks and regain full strength after twelve weeks, depending on injury complexity and adherence to therapy.
Preventing Adhesions and Repair Failure
To minimize the risk of postoperative adhesions, gentle handling of the tendon, proper sheath repair, and early motion protocols are critical. Overly tight sutures or delayed therapy increase the chance of stiffness and repair failure.
Regular follow-up visits allow Dr. Neustein to monitor motion, ensure tendon integrity, and adjust therapy to maximize outcomes.
Managing Associated Injuries
Flexor tendon injuries are often accompanied by damage to extensor tendons, bones, or nerves. When the median nerve or digital nerves are involved, simultaneous nerve repair is performed.
Fractures of the proximal phalanx or middle phalanges are stabilized, and associated soft-tissue wounds are closed to protect the reconstructed tendons.
Outcomes and Prognosis
With timely surgery, precise repair, and consistent rehabilitation, most patients regain near-normal function. The repaired tendons restore DIP flexion, wrist extension, and coordinated motion of the fingers and thumb.
Long-term studies show excellent grip strength and reduced disability when early therapy protocols are followed under specialist supervision.
Potential Complications
Complications are uncommon but may include infection, stiffness, tendon rupture, or delayed healing. Persistent swelling or scar adherence can limit glide at the repair site. These issues are addressed promptly through therapy or, if needed, minor secondary surgery.
Why Choose Dr. Thomas Neustein
Dr. Thomas Neustein is one of the region’s most highly trained hand surgeons, with extensive experience in tendon repair, reconstruction, and microsurgery. His fellowship training in hand and upper extremity surgery provides expertise across both orthopedic and reconstructive techniques.
Patients consistently describe him as a caring, detail-oriented surgeon who takes time to explain every treatment step. His surgical team and office staff are known for professionalism, compassion, and exceptional outcomes.
Comprehensive Care Close to Home
Dr. Neustein treats tendon injuries of all types—from acute lacerations to complex staged reconstructions—at Specialty Orthopaedics offices in Duluth, Dawsonville, and Braselton. Whether your injury involves a single finger, a ruptured tendon, or multiple structures, you can expect top-tier care from diagnosis through recovery.
Schedule an Appointment for Flexor Tendon Evaluation
If you have experienced a tendon injury, difficulty bending your fingers, or loss of grip strength after trauma, schedule an appointment with Dr. Thomas Neustein today. Early evaluation and treatment provide the best opportunity for a complete recovery.
