Hand extensor tendon disruption

1. High-Yield Summary

Extensor tendon disruptions of the hand represent a diverse spectrum of traumatic, athletic, and attritional injuries characterized by loss of active digital extension, joint deformity, and impaired grip biomechanics. Key diagnostic and management principles include:

• Zone-Specific Biomechanics: The extensor mechanism transitions from a thin, broad, avascular aponeurotic hood over the digits (Zones I to IV) to thick, round, vascularized tendons on the dorsum of the hand and wrist (Zones V to VIII), dictating vastly different surgical repair strengths, excursion allowances, and rehabilitation protocols.
• Anatomical Traps & Compensations: Juncturae tendinum across the metacarpal area (Zone VI) can mask a complete laceration of the extensor digitorum communis (EDC) during gross digital extension testing, mandating isolated active extension testing of each individual finger with adjacent digits fully flexed.
• Nonoperative Excellence in Zone I: Closed mallet finger disruptions (Zone I), whether tendinous or bony (involving less than one-third of the articular surface without joint subluxation), achieve excellent union rates with 6 to 8 weeks of strict, uninterrupted distal interphalangeal (DIP) extension splinting. Even momentary DIP flexion during splint changes resets the biologic clock.
• Early Diagnostic Vigilance in Zone III: Closed central slip disruptions over the proximal interphalangeal (PIP) joint can initially present with preserved active extension via intact lateral bands. If untreated, volar migration of the lateral bands subluxates them below the PIP flexion-extension axis, converting them into secondary flexors and establishing a fixed boutonniere deformity. The Elson test is the gold standard clinical diagnostic maneuver.
• Modern Rehabilitation Paradigm: For Zones IV through VII repairs, rigid post-operative immobilization has been largely superseded by early active motion protocols, specifically Relative Motion Extension (RME / ICAM), which significantly improves Total Active Motion (TAM), accelerates functional recovery, and minimizes adhesion formation without increasing tendon rupture risk.

2. Anatomy

The extensor apparatus of the human hand is an intricate biomechanical system composed of extrinsic muscle-tendon units originating in the forearm and intrinsic hand muscles (interossei and lumbricals) inserting into an elaborate dorsal aponeurosis. Successful clinical management requires an exacting understanding of its microarchitecture, retinacular compartments, and safe surgical corridors.

The Dorsal Retinacular Compartments (Zone VII)

At the dorsal wrist, the extensor retinaculum is divided into six distinct osteofibrous tunnels anchored to the distal radius, ulna, and carpal bones, preventing bowstringing during wrist extension:

• First Compartment: Abductor pollicis longus (APL) and extensor pollicis brevis (EPB), bounded radially by the styloid process.
• Second Compartment: Extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB).
• Third Compartment: Extensor pollicis longus (EPL), which hooks around Lister’s tubercle to cross obliquely over the second compartment.
• Fourth Compartment: Extensor digitorum communis (EDC, four slips) and extensor indicis proprius (EIP, running ulnar and deep to the index EDC slip).
• Fifth Compartment: Extensor digiti minimi (EDM), overlying the distal radioulnar joint.
• Sixth Compartment: Extensor carpi ulnaris (ECU), residing within a distinct fibro-osseous groove on the dorsal ulna.

The Digital Extensor Hood & Retinacular Complex (Zones I to IV)

Distal to the metacarpophalangeal (MCP) joints, the central tendon continues across the proximal phalanx and splits into three distinct components: a central slip and two lateral slips:

• Central Slip: Inserts directly onto the dorsal tubercle of the base of the middle phalanx, serving as the primary active extensor of the PIP joint.
• Lateral Bands: Formed by the junction of the lateral slips of the extrinsic tendon with the intrinsic lateral tendons (volar lumbricals and interossei). Over the middle phalanx, the two lateral bands converge distally to form the conjoined terminal extensor tendon, inserting onto the base of the distal phalanx to extend the DIP joint.
• Triangular Ligament: A dorsal fibrous sheet situated over the middle phalanx that bridges the lateral bands, stabilizing them against excessive volar subluxation during PIP flexion.
• Transverse Retinacular Ligament (TRL): Originates from the flexor tendon sheath and inserts into the lateral bands, preventing excessive dorsal migration of the lateral bands during PIP extension.
• Oblique Retinacular Ligament (ORL / Landsmeer): Passes from the A2 flexor pulley and proximal phalanx volar to the PIP joint axis to insert onto the dorsal terminal tendon, creating a passive kinematic link between PIP extension and DIP extension.
• Sagittal Bands (Zone V): Sturdy transverse fibrous structures anchoring the extensor tendon over the MCP joint to the volar plate and intermetacarpal ligament, maintaining the tendon centralized during fist formation.

Surgical Planes & Neurovascular Danger Zones

Dorsal exposures are executed within the subcutaneous tissue plane overlying the paratenon. Critical neurovascular structures at risk include:

• Superficial Branch of the Radial Nerve (SBRN): Emerges between the brachioradialis and ECRL tendons approximately 8 cm proximal to the radial styloid. Courses directly over the first and second extensor compartments; longitudinal traction or transverse incisions risk painful neuroma formation and dysesthesia over the dorsal first web space.
• Dorsal Sensory Branch of the Ulnar Nerve: Arises 5 to 7 cm proximal to the ulnar styloid, passing deep to the flexor carpi ulnaris to cross subcutaneously over the sixth compartment and dorsal ulnar carpus.
• Terminal Posterior Interosseous Nerve (PIN): Located on the floor of the fourth extensor compartment deep to the EDC tendons on the dorsal wrist capsule; often resected during wrist arthrotomy for partial wrist denervation.
• Dorsal Digital Neurovascular Bundles: Cross obliquely along the dorsolateral aspects of the middle and proximal phalanges, vulnerable during lateral or midaxial digital incisions.

3. Pathogenesis

Disruptions of the hand extensor mechanism arise through three primary biomechanical mechanisms: acute sharp laceration, closed traumatic avulsion, and chronic attritional rupture.

• Sharp Open Lacerations: Represent the most common etiology in Zones V, VI, and VII, frequently caused by glass, knife edges, or industrial machinery. Because extensor tendons are superficial and covered by thin subcutaneous tissue, even shallow lacerations frequently sever underlying tendons. Due to digital posture at the time of injury (flexed hand versus extended hand), the skin laceration often does not align with the site of tendon transection, resulting in tendon ends retracting away from the skin wound.
• Closed Hyperflexion Avulsions (Zone I – Mallet Finger): Occur when a forced, sudden flexion force is applied against an actively extended DIP joint (such as a ball striking the tip of an outstretched finger). Tensile failure occurs at the insertion of the terminal tendon into the distal phalanx, resulting in pure tendinous disruption or bony avulsion of the dorsal lip of the distal phalanx.
• Closed Hyperflexion Traumatic Ruptures (Zone III – Central Slip Disruption): Result from sudden forced PIP flexion against active extension or direct dorsal blow over the PIP joint, causing failure of the central slip. Initial attenuation allows gradual lengthening; subsequent dorsal transmission of flexion forces tears the triangular ligament, permitting lateral bands to slide volar to the PIP flexion-extension axis.
• Closed Deceleration / Torsional Forces (Zone V – Sagittal Band Rupture): Commonly termed “boxer’s knuckle,” occurring when a direct blow to the flexed MCP joint tears the radial sagittal band (which is thinner and subjected to greater ulnar deviation stresses than the ulnar band), permitting the extensor tendon to subluxate or dislocate ulnarly into the intermetacarpal groove during fist formation.
• Attritional EPL Rupture: Occurs secondary to ischemia or mechanical friction against the sharp dorsal cortical ridge following nondisplaced distal radius fractures, or secondary to rheumatoid synovitis within the tight third compartment.
• Vaughan-Jackson Syndrome: Progressive attritional rupture of extensor tendons starting from the ulnar side (EDM, ring/small finger EDC slips) caused by friction against a subluxated or scalloped distal ulna (caput ulnae syndrome) in rheumatoid arthritis.
• Mannerfelt Syndrome: Rupture of the flexor pollicis longus and occasionally extensor tendons against an eroded scaphoid tubercle.

4. Natural History

The natural history of untreated extensor tendon disruption is defined by progressive biomechanical decompensation, fixed contractures, and characteristic secondary digital deformities:

• Zone I (Untreated Mallet Finger): Untreated terminal tendon failure initially results in an isolated DIP extension lag (20 to 60 degrees). Over time, all extrinsic and intrinsic extensor power is redirected into the central slip at the middle phalanx. This reciprocal extensor overdrive leads to hyperextension of the PIP joint, while the flexor digitorum profundus (FDP) maintains fixed DIP flexion, producing a debilitating secondary swan-neck deformity.
• Zone III (Untreated Central Slip Disruption): Central slip disruption creates an insidious cascade. At onset, PIP extension may appear preserved due to lateral band compensation. As the patient repeatedly flexes the digit, the triangular ligament attenuates and the lateral bands progressively subluxate volar to the PIP joint’s transverse rotational axis. Once volar, the lateral bands become powerful secondary flexors of the PIP joint while exerting concentrated, uninhibited extension forces on the distal phalanx. This culminates in the classic boutonniere deformity (PIP flexion contracture and DIP hyperextension). Left untreated, the transverse retinacular ligaments and volar plate undergo fixed contracture.
• Zone V (Untreated Sagittal Band Disruption): Chronic subluxation leads to persistent pain, inflammatory tenosynovitis, mechanical triggering, and an inability to initiate digital extension from a clenched fist. The tendon becomes permanently scarred in the ulnar gutter.
• Zones VI & VII (Untreated Midhand & Wrist Lacerations): Severe digital extension lag develops, accompanied by proximal tendon retraction, muscle belly contracture, and dense fibrous adhesion of the distal tendon stump to the metacarpal periosteum, carpus, or dorsal retinaculum. Delayed reconstruction often necessitates tendon transfer or interposition grafting.

5. Clinical Presentation

History

Evaluation begins with a targeted clinical history identifying:

• Mechanism & Energy: Sharp laceration (glass, metal, knife), blunt impact to an extended fingertip, crush injury, or low-energy snap during routine activity (suggesting attritional rupture).
• Hand Posture at Impact: Ascertaining whether the hand was actively gripping or in full extension during laceration predicts the degree of tendon retraction and discordance with the cutaneous wound.
• Contamination Risks: Animal bites, farm equipment, or tooth impact during clenched fist altercation (“fight bite” over Zone V), which introduces virulent oral flora (Eikenella corrodens, Streptococcus viridans, anaerobes).
• Patient Handedness, Occupation, and Timing: Critical for formulating individualized reconstructive goals and early rehabilitation splinting designs.

Physical Exam

Physical examination demands rigorous, isolated joint-by-joint assessment, as superficial gross movement can easily mask severe structural disruption:

• Passive Tenodesis Test: Passively flexing the wrist should induce reciprocal, automatic extension of all digital MCP and IP joints in an intact extensor apparatus. Loss of tenodesis cascade confirms complete structural discontinuity.
• Zone I Assessment: Active DIP extension is tested while the examiner stabilizes the MCP and PIP joints in full extension. Resting extension lag is measured in degrees. Passive extension must be documented to confirm supple joint mobility.
• Zone III Assessment (Elson Test): The patient’s PIP joint is held flexed 90 degrees over the edge of a table while the examiner places a counter-force on the dorsal middle phalanx. The patient attempts to actively extend the PIP joint against resistance. Normal response demonstrates strong extension force against resistance with a completely flaccid DIP joint. Positive finding demonstrates weak PIP extension with marked rigidity and active extension of the DIP joint due to compensatory lateral band overdrive (Sensitivity 95%, Specificity 98%).
• Zone III Assessment (Boyes Test): Active DIP flexion is assessed while the PIP is held in passive full extension. In chronic boutonniere with contracted lateral bands, DIP flexion is restricted.
• Zone V Assessment (Sagittal Band Stability): The examiner inspects the MCP joint during active fist formation and subsequent extension. Sagittal band rupture demonstrates tendon subluxation or frank ulnar dislocation into the intermetacarpal groove during flexion, with an audible or palpable snap or inability to actively extend from a fully flexed posture. If the finger is passively extended, the patient can subsequently maintain extension via the intact extrinsic muscle belly.
• Zone VI Assessment (Isolated EDC Testing): To eliminate spurious extension mediated across adjacent fingers via the oblique juncturae tendinum, each digit must be tested in isolation while holding all adjacent fingers in complete passive flexion.
• EIP and EDM Independence (“Horns Sign”): Tested with the hand flat on the examination table; independent extension of the index finger (EIP) and small finger (EDM) confirms integrity of their dedicated extrinsic units.
• Neurovascular Audit: Static and moving two-point discrimination (<6 mm normal) along both digital borders and radial/ulnar pulses or capillary refill (<2 seconds).

6. Imaging and Diagnostic Studies

Diagnostic imaging confirms bony participation, quantifies articular displacement, and identifies occult soft-tissue discontinuity:

• Plain Radiography (Standard Digit & Hand Views): High-resolution posteroanterior (PA), true lateral, and oblique views of the affected digit or hand. Dedicated true lateral views of the digit are essential in Zone I and Zone III injuries to evaluate avulsion fracture fragments, percentage of articular surface involvement (greater than one-third indicates instability), and volar subluxation of the distal or middle phalanx. Hand PA and oblique views screen for foreign bodies (glass, metallic debris) and periarticular MCP fractures in “fight bites.”
• High-Frequency Diagnostic Ultrasound: High-frequency linear transducers (15 to 22 MHz) provide dynamic, cost-effective evaluation of superficial extensor tendons. Ultrasound enables direct visualization of tendon fiber discontinuity, fluid hematoma within the gap, measurement of retraction distance in millimeters, reliable differentiation of partial lacerations (<50% tendon width) from complete tears, and dynamic detection of sagittal band snapping during active motion.
• Magnetic Resonance Imaging (MRI): Reserved for complex, chronic, or occult presentations, including suspected closed central slip attenuation with equivocal physical findings, rheumatoid wrist pannus, and multi-tendon attritional ruptures (Vaughan-Jackson syndrome) to delineate tendon stump viability and guide surgical reconstructive planning.

7. Classification

The definitive anatomical classification of extensor tendon injuries is the Verdan / Kleinert Zone System, dividing the dorsal upper extremity into eight distinct zones in the fingers (with an expanded ninth zone for forearm muscle bellies) and five specialized zones for the thumb. This structural classification directly dictates surgical approach, suture technique, and rehabilitation protocols.

Doyle Classification of Zone I Mallet Injuries

To guide the surgical versus nonoperative treatment of Zone I mallet disruptions, Doyle established a clinical sub-classification:

8. Treatment

Medical / Nonoperative Management

Nonoperative management is the standard of care for closed Zone I injuries, acute closed Zone III injuries, partial tendon lacerations involving less than 50% of the tendon width, and stable sagittal band strains:

• Zone I Closed Mallet Protocol: Application of a custom dorsal thermoplastic, Stack, or padded aluminum splint maintaining the DIP joint in neutral to slight hyperextension (0 to 5 degrees). Excessive hyperextension must be strictly avoided to prevent dorsal skin blanching and cutaneous ischemic necrosis. Duration is 6 to 8 weeks of uninterrupted, continuous wear, followed by 4 to 6 weeks of night-only splinting. If the DIP joint is allowed to flex even momentarily during splint changes, the healing fibrous callus ruptures, resetting the 6-week immobilization timeline back to day one.
• Zone III Closed Central Slip Protocol: Splinting of the PIP joint in absolute full extension (0 degrees) for 6 weeks. The DIP joint is deliberately left free, and the patient is instructed to perform active DIP flexion exercises. FDP contraction pulls the lateral bands and oblique retinacular ligaments distally and dorsally, preventing lateral band contracture and actively reducing the healing central slip onto its middle phalanx footprint.
• Partial Tendon Lacerations (<50% Tendon Width): Supported by contemporary systematic reviews, partial lacerations involving less than 50% of the tendon width without mechanical catching or extension lag can be safely treated nonoperatively without suture repair. The wound is debrided and skin closed, followed by 1 to 2 weeks of protective splinting and immediate active motion, avoiding suture-induced scar formation, tenodesis, and localized tissue bulk.

Operative Management

The primary goals of extensor tendon surgery are anatomic structural restoration, minimal surgical bulk to permit smooth excursion beneath the thin dorsal integument, secure tensile strength to withstand early motion, and prevention of joint stiffness.

• Zone I Operative Techniques: Open lacerations (Type II) undergo dermatotenodesis using 4-0 or 5-0 braided absorbable or monofilament sutures capturing both the dorsal skin margin and the divided tendon stump in a single mattress throw, combined with a trans-articular 1.0 mm (0.035-inch) K-wire pinning the DIP joint in neutral for 6 weeks. Displaced mallet fractures (Type IV-B/C) undergo percutaneous extension-block pinning (Ishiguro technique) or open reduction with mini-screw/wire fixation.
• Zone III Operative Techniques: Sharp transections are repaired using a modified Kessler or horizontal mattress core suture using 4-0 nonabsorbable braided suture, supplemented with a 5-0 or 6-0 running epitendinous stitch. Avulsions from the middle phalanx footprint are re-anchored using miniature 1.3 to 1.5 mm suture anchors or pull-out transosseous sutures. If the lateral bands are subluxated volarly, their dorsal margins are mobilized and re-approximated with fine interrupted 5-0 sutures over the middle phalanx to reconstruct the triangular ligament.
• Zone V Operative Techniques: Primary edge-to-edge repair of the torn radial sagittal band using 4-0 nonabsorbable braided mattress sutures is performed for acute ruptures. In chronic cases, a slip of the EDC tendon is detached proximally, passed deep to the deep transverse intermetacarpal ligament, and looped back onto itself to centralize the tendon. Contaminated human tooth altercation wounds (“fight bites”) are never closed primarily; they require emergent formal surgical debridement, extensive pulsatile arthrotomy irrigation of the MCP joint, intravenous antibiotics targeting oral contaminants, and delayed secondary closure.
• Zones VI & VII Operative Techniques: Rounder tendon morphology permits robust 4-strand core repairs (double modified Kessler or cruciate sutures) using 3-0 or 4-0 braided synthetic sutures, supplemented with a circumferential 5-0 running epitendinous suture to bury suture knots and optimize gliding. In Zone VII, the extensor retinaculum is released in a step-cut (Z-lengthening) configuration, and repaired tendons are placed superficial to the retinaculum or a portion is reconstructed as a loose pulley to prevent bowstringing without tunnel entrapment.
• Postoperative Rehabilitation Paradigms: Historically protected by static immobilization (wrist 30 degrees extension, MCP 15 to 20 degrees flexion for 4 to 6 weeks), modern protocols favor Relative Motion Extension (RME / ICAM protocol) or dynamic outrigger splinting. RME utilizes a low-profile hand splint holding the injured digit in 15 to 20 degrees greater MCP extension relative to adjacent uninjured digits, permitting safe immediate active digital motion within the first postoperative week, yielding superior Total Active Motion (TAM) and lower adhesion rates without increasing rupture risk.

Indications & Contraindications

• Absolute Indications for Surgery: Open extensor tendon lacerations with >50% structural transection; mallet fracture involving >30% to 50% of the articular surface; any mallet fracture accompanied by volar subluxation of the distal phalanx; acute open central slip transection or displaced bone avulsion of the middle phalanx; extensor tendon dislocation at the MCP joint failing closed conservative management; contaminated “fight bite” laceration requiring open joint washout.
• Relative Indications for Surgery: Chronic mallet finger deformity with functional impairment in young, active patients failing prolonged splinting; chronic flexible boutonniere deformity failing therapy.
• Contraindications to Primary Repair: Active, uncontrolled wound sepsis or gross purulence (staged debridement and delayed reconstruction indicated); severe crush injury with massive cutaneous tissue loss (coverage takes precedence over tendon repair); fixed joint contractures (arthrogenic contractures must be mobilized prior to tendon reconstruction); patient noncompliance or cognitive inability to participate in protective splinting.

9. Outcome

Clinical outcomes following extensor tendon repair depend heavily on the anatomic zone of injury, associated soft-tissue or skeletal trauma, patient age, and the postoperative rehabilitation strategy. Validated assessment tools include Miller’s Criteria and Total Active Motion (TAM) scores.

Miller’s Assessment Criteria for Extensor Tendon Repair

Long-term prospective trials demonstrate that closed mallet finger management achieves successful fibrous or bony union in 80% to 90% of compliant patients, with an average residual extension lag of less than 5 to 8 degrees, which produces negligible subjective disability. In Zones V and VI, comparative trials establish that early active motion via relative motion extension splinting delivers significantly superior early TAM (mean 240° vs 205° at 6 weeks) and earlier return to unrestricted work (average 5.8 weeks vs 9.2 weeks) compared to static immobilization, with secondary rupture rates below 2%.

10. Complications

Complications following extensor tendon disruption can be categorized by chronologic onset:

11. Pearls and Pitfalls

• Pearl (The Tenodesis Test Never Lies): Always assess passive wrist tenodesis before administering local anesthetic or nerve blocks. Automatic digital extension during passive wrist flexion confirms macroscopic extensor tendon continuity; absence of extension in any digit pinpoint an extensor tendon disruption with 100% specificity.
• Pearl (Skin Incision Extension): When exploring dorsal lacerations, never extend wounds linearly across flexion creases. Utilize Bruner zig-zag extensions or lazy-S incisions to avoid creating longitudinal scar contractures that restrict digital flexion.
• Pearl (The “Horns” Sign for Independent Extensors): To verify EIP and EDM integrity, ask the patient to make a fist with the middle and ring fingers while extending the index and small fingers. This isolates the dedicated independent extensors from the shared EDC system.
• Pitfall (The Juncturae Tendinum Trap): Never rely on composite active extension of all four fingers to rule out an EDC laceration. In Zone VI, the juncturae tendinum can transmit extension forces from adjacent intact tendons, producing near-normal extension even with a completely divided EDC slip. Always test each digit individually with adjacent digits fully flexed.
• Pitfall (Blanching the Dorsal Mallet Skin): Splinting a mallet finger in extreme hyperextension will cause cutaneous blanching and ischemic necrosis over the thin dorsal skin of the DIP joint. Position the joint in neutral (0 degrees) or at most 5 degrees of extension. If the dorsal skin is white, the splint is too tight.
• Pitfall (Missing the “Fight Bite”): Any small laceration overlying the MCP joint in a patient following an altercation must be treated as an open human bite wound with MCP joint capsule penetration until proven otherwise. Never close these wounds primarily in the emergency department; perform formal operative irrigation and debridement.

12. Controversy

Several significant controversies persist regarding optimal surgical decision-making and postoperative rehabilitation in hand extensor tendon disruptions:

• Relative Motion Extension vs. Dynamic vs. Static Splinting: While historically protected by 4 to 6 weeks of rigid static immobilization, substantial Level I randomized trials now endorse early active motion. Advocates of Relative Motion Extension (RME / ICAM) demonstrate faster functional return, superior Total Active Motion (TAM), and higher patient satisfaction compared to bulky dynamic outrigger splints. Critics caution that RME requires high cognitive compliance and precise fabrication by an experienced hand therapist, making static splinting safer in noncompliant cohorts.
• Management of Large Bony Mallet Fractures: The threshold for surgical fixation versus closed splinting in bony mallet injuries involving 30% to 50% of the articular surface remains hotly debated. While surgical fixation (such as Ishiguro extension-block pinning) restores anatomic articular alignment, multiple comparative studies show that closed extension splinting achieves equivalent long-term functional and subjective outcomes despite radiographic articular remodeling and mild dorsal prominence, avoiding the surgical risks of nail bed injury, pin tract infection, and recurrent displacement.
• Suture Repair vs. Conservative Debridement in Partial Lacerations: Traditional surgical dogma favored suture repair of any extensor tendon laceration exceeding 30% to 50% of its cross-sectional area to prevent secondary rupture. However, recent systematic reviews and biomechanical evidence reveal that suture repair creates localized bulbous tenodesis, snagging beneath the retinaculum, and tendon adhesion without improving ultimate failure load compared to wound irrigation, skin closure, and early protected mobilization.

13. Evidence-Based Synthesis

Modern clinical decision-making is grounded in high-quality randomized controlled trials and prospective registry analyses, corroborated by seminal biomechanical and anatomical descriptions.

14. References

• Newport ML. Extensor Tendon Injuries in the Hand. J Am Acad Orthop Surg. 1997. doi:10.5435/00124635-199703000-00001 [Level IV: Clinical Case Series / Cohort Study]
• Collocott SJF, Kelly E, Foster M et al. A randomized clinical trial comparing early active motion programs: Earlier hand function, TAM, and orthotic satisfaction with a relative motion extension program for zones V and VI extensor tendon repairs. J Hand Ther. 2020. doi:10.1016/j.jht.2018.10.003 [Level I: Randomized Controlled Trial]
• Mowlavi A, Burns M, Brown RE. Dynamic versus static splinting of simple zone V and zone VI extensor tendon repairs: a prospective, randomized, controlled study. Plast Reconstr Surg. 2005. doi:10.1097/01.prs.0000149479.96088.5d [Level I: Randomized Controlled Trial]
• Dickson K, Mantelakis A, Reed AJM et al. The management of partial extensor tendon lacerations of the hand and forearm: A systematic review. J Plast Reconstr Aesthet Surg. 2023. doi:10.1016/j.bjps.2023.06.004 [Level I: Systematic Review / Meta-Analysis]
• Hall B, Lee H, Page R et al. Comparing three postoperative treatment protocols for extensor tendon repair in zones V and VI of the hand. Am J Occup Ther. 2010. doi:10.5014/ajot.2010.09091 [Level I: Randomized Controlled Trial]

15. Master Class Pro-Tip

When operating in Zone VII under the extensor retinaculum, never re-approximate the entire fibrous roof directly over your tenorrhaphy. Suture knots, tissue bulk, and post-repair edema will create an immediate mechanical bottleneck, resulting in devastating tendon tenodesis and severe loss of digital flexion. Instead, perform an oblique or step-cut Z-lengthening of the retinaculum. Transpose one-half of the retinaculum beneath the repaired tendons to recreate a smooth gliding floor over the bare carpal bones, and use the remaining half as a partial, loose pulley to prevent bowstringing during active wrist extension. Intraoperatively, verify that complete passive wrist and finger flexion can be achieved without any hitching or impingement of the repair site.

Master Class Surgical Pearl: Hand Extensor Tendon Disruption