Hand Surgery

01 Hand, Wrist & Forearm Anatomy Essentials

Hand surgery covers the fingertips to the elbow. The hand surgeon operates on bone, tendon, nerve, vessel, skin, and joint in a space the size of a deck of cards — which means anatomic precision is everything. Scribes must master the vocabulary of this anatomy because the surgeon will narrate it continuously during exam and in operative notes.

Osseous Anatomy

The wrist is built around eight carpal bones arranged in two rows. The proximal row (radial to ulnar) contains the scaphoid, lunate, triquetrum, and pisiform. The distal row contains the trapezium, trapezoid, capitate, and hamate. The mnemonic Some Lovers Try Positions That They Can't Handle captures the order. Distal to the carpus are five metacarpals (MC1 = thumb through MC5 = small finger) and the 14 phalanges: each finger has a proximal (P1), middle (P2), and distal (P3) phalanx, while the thumb has only P1 and P2.

The joints follow the bones: radiocarpal joint (distal radius to scaphoid/lunate), midcarpal joint (between proximal and distal carpal rows), CMC joints (carpometacarpal, especially the saddle-shaped thumb CMC), MCP joints (metacarpophalangeal, the knuckles), PIP joints (proximal interphalangeal), and DIP joints (distal interphalangeal). The thumb has only one IP joint.

Tendons

The hand is moved by two sets of tendons. The flexor tendons travel on the palmar side; the superficial flexors include flexor carpi radialis (FCR), palmaris longus (PL, absent in ~15%), and flexor carpi ulnaris (FCU), while the digital flexors are the flexor digitorum superficialis (FDS) inserting on the middle phalanx and flexor digitorum profundus (FDP) inserting on the distal phalanx. The thumb flexor is flexor pollicis longus (FPL). Flexor tendons run through a fibro-osseous sheath with a pulley system — the critical A2 and A4 pulleys must be preserved to prevent bowstringing.

The extensor tendons travel on the dorsum of the wrist in six synovial compartments:

Nerves

Three nerves drive hand function. The median nerve enters the hand through the carpal tunnel, supplies the thenar musculature (abductor pollicis brevis, opponens pollicis, superficial flexor pollicis brevis), the radial two lumbricals, and sensation to the radial 3.5 digits (palmar surface) plus the dorsal tips of index/middle fingers. The ulnar nerve passes through Guyon canal, supplies the hypothenar muscles, interossei, ulnar two lumbricals, adductor pollicis, deep FPB head, and sensation to the ulnar 1.5 digits. The radial nerve divides into the posterior interosseous nerve (PIN) for wrist/finger extension and the superficial radial nerve (SRN) for sensation to the dorsoradial hand.

Intrinsic vs Extrinsic Muscles

The extrinsic muscles originate in the forearm and cross the wrist to act on the hand — these are the powerful flexors and extensors. The intrinsic muscles originate within the hand itself and provide fine motor control: the thenar group (APB, OP, FPB, adductor pollicis), hypothenar group (ADM, FDM, ODM), four lumbricals (arising from FDP tendons), three palmar interossei (adduction, PAD), and four dorsal interossei (abduction, DAB). Intrinsic paralysis (ulnar palsy) produces the classic "claw hand" — MCP hyperextension and IP flexion of the ring and small fingers — because the lumbricals normally balance the long extensors.

Vascular Anatomy

The hand receives dual blood supply from the radial artery (radial side, dorsum, deep palmar arch) and ulnar artery (ulnar side, superficial palmar arch). The two arches anastomose, which is why the Allen test is used to confirm patency of both vessels before radial artery harvest or arterial line placement. The common digital arteries branch from the superficial arch and bifurcate into proper digital arteries that run on the volar/radial and volar/ulnar aspects of each finger.

02 Scribe Documentation Framework

Hand surgery encounters split into three main flavors: acute trauma (ED consults, fractures, lacerations, infections), chronic elective (carpal tunnel, trigger finger, arthritis, Dupuytren), and post-operative follow-up. Each has a distinct documentation rhythm.

03 Distal Radius Fractures Fracture

The distal radius fracture is the most common fracture of the upper extremity. It occurs across three demographic peaks: pediatric falls, young high-energy trauma (MVCs, sports, falls from height), and low-energy osteoporotic fractures in older adults — particularly postmenopausal women. A scribe will see these in both the ED consult context and the post-reduction follow-up clinic.

Named Patterns

• Colles fracture: Extra-articular distal radius fracture with dorsal angulation ("dinner fork deformity"). The classic FOOSH injury.
• Smith fracture: Reverse Colles — distal radius fracture with volar angulation ("garden spade deformity"). Mechanism is typically a fall on the dorsum of the flexed wrist.
• Barton fracture: Intra-articular fracture-dislocation of the distal radius. Volar (more common) or dorsal rim fragment with carpus displaced along the fragment.
• Chauffeur fracture: Intra-articular radial styloid fracture. Named for hand-crank starters that kicked back; now more often seen with scapholunate ligament injury.
• Die-punch fracture: Depressed lunate facet fragment from axial load.

Evaluation & Parameters

Wrist x-rays (PA, lateral, oblique) are the workhorse. The surgeon will measure and dictate three critical radiographic parameters: radial height (normal ~11 mm), radial inclination (normal ~22°), and volar tilt (normal ~11° volar). Loss of these — especially volar tilt reversing into dorsal angulation — drives the decision to operate. Also document articular step-off, comminution, ulnar styloid involvement, and DRUJ congruence.

Classification

The Frykman classification organizes distal radius fractures by involvement of the radiocarpal joint, DRUJ, and ulnar styloid:

Management

Non-displaced or minimally displaced fractures are managed in a sugar-tong or short-arm cast for 4–6 weeks. Displaced fractures are reduced under hematoma block or conscious sedation. Operative indications include intra-articular step-off >2 mm, loss of radial length >5 mm, dorsal angulation >5–10°, and failed closed reduction. The workhorse operation is open reduction internal fixation with a volar locking plate. Alternatives include percutaneous pinning, external fixation, and dorsal bridge plating for severely comminuted fractures. AAOS 2020 clinical practice guideline on distal radius fractures provides current evidence on operative vs nonoperative thresholds, especially in older adults.

04 Scaphoid & Carpal Bone Fractures Fracture

The scaphoid is the most commonly fractured carpal bone (60–70% of carpal fractures). It is notorious for nonunion and avascular necrosis because its blood supply enters through the distal pole — a proximal pole fracture interrupts flow to the proximal fragment. Classic mechanism is FOOSH with the wrist extended.

Presentation & Workup

Anatomic snuffbox tenderness plus scaphoid tubercle tenderness plus pain on axial compression of the thumb is highly suggestive. Initial x-rays (PA, lateral, oblique, scaphoid view with ulnar deviation) miss up to 25% of acute fractures. Patients with a clinical suspicion and negative films are splinted in a thumb spica and brought back at 10–14 days for repeat imaging, or advanced imaging (MRI or CT) is obtained immediately.

Classification & Management

The Mayo classification divides scaphoid fractures by location: distal pole, waist (most common, ~65%), and proximal pole (highest nonunion risk). Non-displaced distal or waist fractures are treated in a thumb spica cast for 8–12 weeks. Displaced fractures (>1 mm), proximal pole fractures, and fractures with humpback deformity are treated with open or percutaneous compression screw fixation (typically a Herbert or Acutrak headless compression screw). Scaphoid nonunion advanced collapse (SNAC wrist) is a late complication requiring salvage procedures such as proximal row carpectomy or four-corner fusion.

Other Carpal Fractures

Hook of hamate fractures (baseball/golf/racquet sports) cause ulnar wrist pain and can irritate the ulnar nerve in Guyon canal. CT of the carpal tunnel is the best imaging study; treatment is hook excision if symptomatic or non-union develops. Triquetral fractures (dorsal avulsion from wrist hyperflexion) are common but usually heal with 4–6 weeks of immobilization in a short-arm cast. Pisiform fractures are treated symptomatically, with pisiformectomy reserved for persistent pain. Capitate, trapezium, and lunate fractures are rare but important — acute lunate fractures can precede Kienböck disease.

05 Carpal Instability & Perilunate Injuries Ligament

The carpus is held together by intrinsic (bone-to-bone) and extrinsic (forearm-to-carpus) ligaments. Disruption produces instability patterns.

Scapholunate (SL) Dissociation

The SL ligament links the scaphoid and lunate. Rupture causes the scaphoid to flex and the lunate to extend (DISI — dorsal intercalated segmental instability). On PA x-ray, look for an SL gap >3 mm ("Terry Thomas sign") and a cortical ring sign from the foreshortened, flexed scaphoid. On lateral, the SL angle is >60° (normal 30–60°). Watson scaphoid shift test is provocative. Untreated SL dissociation progresses to scapholunate advanced collapse (SLAC wrist). Treatment ranges from acute ligament repair to reconstruction (Brunelli, SLIC screw) to salvage (PRC, four-corner fusion).

Lunotriquetral (LT) Injury

Less common. Causes ulnar-sided wrist pain. Produces VISI (volar intercalated segmental instability). Diagnosed with lunotriquetral ballottement (Reagan test) and arthrography or MR.

Perilunate Dislocation

A high-energy injury (FOOSH with hyperextension). The carpus dislocates around the lunate in a progressive pattern described by Mayfield stages:

These are urgent — require emergent reduction, open repair of the ligaments, and pinning. Median nerve compression is common and may require acute carpal tunnel release.

Kienböck Disease

Avascular necrosis of the lunate, often in young manual laborers with negative ulnar variance. Staged using the Lichtman classification:

Treatment includes immobilization, joint-leveling procedures (radial shortening osteotomy), revascularization, and salvage arthrodesis.

06 TFCC Injury & DRUJ Instability Ligament

The triangular fibrocartilage complex (TFCC) is the meniscus of the wrist — a shock-absorbing and stabilizing structure on the ulnar side. It connects the distal radius to the ulnar styloid and stabilizes the distal radioulnar joint (DRUJ). Injuries cause ulnar-sided wrist pain with clicking, and worsen with forearm rotation and gripping.

The Palmer classification splits TFCC lesions into traumatic (Class 1) and degenerative (Class 2) categories. Class 1A is a central perforation; 1B is an ulnar avulsion (often with DRUJ instability); 1C is a volar distal avulsion; 1D is a radial avulsion. Class 2 lesions represent progressive ulnocarpal impaction, especially in positive ulnar variance wrists.

Evaluation includes ulnar fovea sign, piano key test (for DRUJ instability), and MRI or MR arthrogram. Treatment ranges from splinting and cortisone injection to arthroscopic TFCC debridement or repair, ulnar shortening osteotomy for ulnocarpal impaction, and DRUJ reconstruction (Adams-Berger ligament reconstruction with palmaris longus graft).

DRUJ Instability & Ulnar Variance

The DRUJ allows forearm rotation (pronation/supination). Instability causes painful clunking with rotation and loss of grip strength. Exam: piano key sign (dorsally displaced ulnar head that "springs back"), pain with loaded rotation. Imaging: PA wrist films in neutral rotation to assess ulnar variance (positive, neutral, or negative) — positive variance predisposes to ulnocarpal impaction. Chronic instability after distal radius malunion may require corrective osteotomy of the radius or ulnar shortening.

07 Metacarpal & Phalangeal Fractures Fracture

Metacarpal Fractures

Boxer fracture: fifth metacarpal neck fracture from punching a solid object. Tolerates up to 40° of volar angulation in the small finger before treatment is needed. Always rule out a fight bite — a laceration over the MCP from striking teeth — which is a surgical emergency due to the risk of Eikenella/oral flora septic arthritis.

Bennett fracture: intra-articular fracture-dislocation of the base of the thumb metacarpal. The volar-ulnar fragment remains attached to the anterior oblique ligament while the shaft is pulled proximally and radially by APL. Requires reduction and pinning or ORIF.

Rolando fracture: comminuted (Y- or T-shaped) intra-articular fracture of the thumb metacarpal base. Worse prognosis than Bennett; may require ORIF or external fixation.

Phalangeal Fractures

Proximal, middle, and distal phalanx fractures are managed by location (base, shaft, neck, condyle) and rotation. Malrotation is the critical finding — the fingers should point toward the scaphoid tubercle when flexed. Even 5° of rotation creates significant finger scissoring. Displaced, rotated, or intra-articular fractures are managed with CRPP, ORIF with mini plates and screws, or dynamic traction.

08 Tendon Injuries (Flexor & Extensor) Tendon

Flexor Tendon Zones (Verdan)

Flexor tendon lacerations are classified by the level at which they occur. The Verdan zones:

The thumb uses a separate T1–T3 system.

Classic exam: FDS is tested by holding all other digits in extension while the patient flexes the PIP of the tested finger. FDP is tested by isolated DIP flexion. Repair is typically within 7–10 days using a modified Kessler, Tajima, or Massachusetts General Hospital (MGH/Strickland) core suture (often 4- or 6-strand) with a running epitendinous suture. Post-op rehabilitation uses early passive or active motion protocols (Duran, Kleinert, or Indiana). The Strickland formula measures outcome as percentage of normal PIP+DIP motion.

Jersey Finger

Avulsion of the FDP from the distal phalanx, classically when a defender grabs a jersey. Ring finger is most common. Classified by Leddy and Packer (I: retraction into palm, severed vincula — repair within 7–10 days; II: retraction to PIP, vincula intact; III: retraction to A4 with bony fragment).

Extensor Tendon Zones & Injuries

Extensor zones are 1–8 over the fingers/wrist. Mallet finger (Zone 1): terminal extensor tendon avulsion causing DIP droop; treated with 6–8 weeks of continuous DIP extension splinting. Central slip injury / boutonnière deformity (Zone 3): PIP flexion, DIP hyperextension. Swan neck deformity: PIP hyperextension, DIP flexion — often from volar plate laxity or intrinsic tightness. Open extensor lacerations are repaired with a figure-of-eight or mattress suture.

09 Stenosing Tenosynovitis Tendon

Trigger Finger

Thickening of the A1 pulley traps a nodular flexor tendon, causing catching, locking, and pain at the MCP. More common in diabetics and women 40–60. Graded by the Quinnell/Green classification:

Treatment: activity modification and NSAIDs, corticosteroid injection into the flexor sheath (up to 2–3 injections), and A1 pulley release (open or percutaneous) for refractory cases.

de Quervain Tenosynovitis

Stenosing tenosynovitis of the first dorsal extensor compartment (APL and EPB). Presents with radial-sided wrist pain, worse with thumb use (classic in new mothers lifting infants). Provocative tests: Finkelstein (examiner ulnarly deviates the wrist with the thumb in the fist), Eichhoff (patient tucks thumb into fist and ulnar-deviates), WHAT (wrist hyperflexion and abduction of thumb) test. Treatment: thumb spica splint, NSAIDs, corticosteroid injection, and first dorsal compartment release if refractory. Watch for a separate EPB subcompartment during surgery.

Intersection Syndrome

Inflammation where the first dorsal compartment (APL/EPB) crosses over the second (ECRL/ECRB) approximately 4 cm proximal to Lister tubercle. Presents with dorsoradial forearm pain and crepitus. Managed with splinting, NSAIDs, and activity modification.

10 Compressive Neuropathies of the Upper Extremity Nerve

Carpal Tunnel Syndrome (CTS)

The most common compressive neuropathy. Median nerve compression beneath the transverse carpal ligament causes numbness/tingling in the radial 3.5 digits, classically waking patients at night and provoked by activities like driving or holding a phone. Risk factors include female sex, obesity, pregnancy, diabetes, hypothyroidism, and repetitive wrist flexion. Advanced cases produce thenar atrophy and weakness of thumb opposition.

Provocative tests: Phalen (wrist flexion reproduces symptoms in <60 seconds), Tinel sign (tapping over the median nerve at the wrist), and Durkan carpal compression test (direct compression on the median nerve, most sensitive). Electrodiagnostic studies (EMG/NCS) confirm slowed median sensory and motor conduction at the wrist. AAOS clinical practice guideline on carpal tunnel syndrome management endorses nocturnal neutral-wrist splinting, corticosteroid injection, and surgical release — either open carpal tunnel release (OCTR) or endoscopic (ECTR) — for refractory or severe cases.

Cubital Tunnel Syndrome

Ulnar nerve compression at the elbow, the second most common compressive neuropathy. Presents with ring/small finger numbness, weakness of grip and pinch, and positive Froment sign (compensatory thumb IP flexion by FPL when adducting the thumb against a piece of paper) and Wartenberg sign (small finger abducted). Nighttime elbow flexion worsens symptoms. Treatment: avoid prolonged elbow flexion, night extension splint, and surgical decompression — in situ release, subcutaneous transposition, or submuscular transposition, sometimes with medial epicondylectomy.

Guyon Canal Syndrome (Ulnar Tunnel)

Ulnar nerve compression at the wrist. Causes include hook of hamate fracture, ganglion cyst, and prolonged handlebar pressure ("cyclist's palsy"). Zone of compression (Shea and McClain) determines whether sensory, motor, or both are affected. Treatment is activity modification, splinting, and surgical release.

Radial Tunnel & PIN Syndrome

Compression of the radial nerve/PIN in the proximal forearm. Radial tunnel syndrome causes lateral elbow pain mimicking lateral epicondylitis but with tenderness ~4 cm distal to the lateral epicondyle. PIN syndrome causes motor weakness (finger drop, radial wrist extension with deviation because ECRL is spared) without sensory loss. Common sites of compression include the arcade of Fröhse (fibrous edge of supinator).

Anterior Interosseous Nerve (AIN) Syndrome / Pronator Syndrome

AIN is a pure motor branch — compression causes weakness of FPL, FDP to index, and pronator quadratus; the patient cannot make the "OK sign" because they can't flex the IP of the thumb and DIP of the index. Pronator syndrome involves median nerve compression at the elbow/proximal forearm (between pronator teres heads or at the lacertus fibrosus) and includes both motor and sensory symptoms — unlike CTS, it affects the palmar cutaneous branch so the thenar palm is also numb.

11 Peripheral Nerve Injuries & Brachial Plexus Nerve

Nerve injuries are graded with the Seddon and Sunderland classifications:

Repair options include direct epineurial repair, nerve grafting (sural, MABC, AIN-to-ulnar transfer), nerve conduits, and motor/sensory nerve transfers. The hand surgeon often works with microsurgery colleagues for brachial plexus reconstruction.

Tendon transfers restore function after high-level nerve palsy: for high radial nerve palsy, a typical set is PT→ECRB, FCR→EDC, PL→EPL. Low median nerve palsy can use an opposition transfer (Camitz/PL, Huber, Bunnell/FDS ring). Low ulnar palsy can use Zancolli lasso, Brand, or FDS ring finger transfers for claw correction.

12 Dupuytren Contracture Soft tissue

A progressive fibroproliferative disease of the palmar and digital fascia producing cords and nodules that pull the fingers (especially ring and small) into flexion contracture. Northern European ancestry, diabetes, smoking, alcohol use, and male sex are risk factors (the so-called "Dupuytren diathesis"). The affected structures are pathologic cords derived from the pretendinous band, spiral band, lateral digital sheet, Grayson ligament, and natatory ligament — the Cleland ligament is spared.

Table-top test: the patient cannot place the palm flat on a table once the MCP contracture exceeds ~30°. Treatment options:

• Observation for mild, non-progressing disease.
• Collagenase clostridium histolyticum injection followed by manipulation (Xiaflex).
• Percutaneous needle aponeurotomy — minimally invasive cord division.
• Open fasciectomy (regional or limited) — the definitive procedure, removing the diseased fascia.
• Dermofasciectomy with skin grafting for recurrent or aggressive disease.

Digital nerves can spiral within the cord and are at risk during surgery. Post-op splinting and hand therapy are standard.

13 Hand & Wrist Masses / Tumors Soft tissue

Ganglion cyst: the most common hand mass (60–70%). Mucinous fluid from a joint or tendon sheath. Dorsal wrist ganglia (70%) arise from the scapholunate ligament; volar wrist ganglia arise from the radiocarpal or STT joint and are adjacent to the radial artery; retinacular cysts come from the flexor tendon sheath. Treatment: observation, aspiration, or excision back to the stalk.

Giant cell tumor of tendon sheath (GCTTS): the second most common hand tumor; firm, slow-growing, often along a flexor tendon sheath. Treatment is marginal excision; recurrence is common.

Mucous cyst: a ganglion arising from the DIP joint in OA, often with nail grooving from pressure on the germinal matrix.

Glomus tumor: rare benign neoplasm of the glomus body, usually subungual. Classic triad: pinpoint tenderness, cold sensitivity, paroxysmal pain. Treatment is excision.

Enchondroma: the most common primary bone tumor of the hand. Usually discovered incidentally or after pathologic fracture. Treated with curettage and bone grafting.

Epidermal inclusion cyst, lipoma, schwannoma, and vascular malformations round out the differential.

14 Hand Infections Infection

• Paronychia: infection of the nail fold. Acute — usually Staph aureus; treated with warm soaks, oral antibiotics, and drainage if an abscess is present. Chronic — often Candida, in dishwashers and diabetics.
• Felon: closed-space infection of the pulp of the fingertip. Intensely painful. Drained through a longitudinal or lateral incision, breaking the vertical septa.
• Herpetic whitlow: HSV infection of the finger (clear vesicles, historically in dental/medical workers). Do NOT incise — manage with acyclovir.
• Deep space infections: thenar space, midpalmar space, Parona space. Require operative drainage and IV antibiotics.
• Septic arthritis: often after a fight bite at the MCP joint. Urgent washout, IV antibiotics.
• Animal and human bites: Pasteurella (dog/cat), Eikenella (human). Standard prophylaxis is amoxicillin-clavulanate; consider tetanus and rabies.
• Necrotizing fasciitis: pain out of proportion, crepitus, bullae, rapid progression — emergent debridement and broad-spectrum antibiotics.

IDSA practice guidelines for skin and soft tissue infections inform empiric antibiotic selection and drainage decisions.

Complex Regional Pain Syndrome (CRPS)

CRPS type 1 (reflex sympathetic dystrophy) occurs after trauma without nerve injury; type 2 (causalgia) follows a defined nerve injury. Presentation includes disproportionate burning pain, allodynia, hyperalgesia, edema, temperature asymmetry, trophic skin/nail changes, and motor dysfunction. Diagnosis is clinical via the Budapest criteria. Treatment is multimodal: early hand therapy (desensitization, mirror therapy), neuropathic medications (gabapentin, pregabalin, TCAs), stellate ganglion blocks, and avoidance of unnecessary surgery. Early recognition and aggressive therapy dramatically improve outcomes.

15 Arthritis of the Hand & Wrist Joint

Thumb CMC (Basal Joint) Arthritis

Osteoarthritis of the first carpometacarpal (trapeziometacarpal) joint is extremely common, especially in postmenopausal women. Presents with pain at the base of the thumb, weakness of pinch, and a "shouldered" appearance of the CMC. Grind test (axial compression with rotation) reproduces pain. Staged with the Eaton-Littler classification:

Treatment: splinting, NSAIDs, injection, and operative options including trapeziectomy with ligament reconstruction and tendon interposition (LRTI), suspensionplasty, CMC arthrodesis, or arthroplasty.

Hand Rheumatoid Arthritis

RA produces symmetric inflammatory arthritis affecting the MCP and PIP joints (DIPs are classically spared). Deformities include ulnar drift at the MCPs, swan neck, boutonnière, and caput ulnae at the wrist. Tendon ruptures at Lister tubercle (EPL) and over the distal ulna (EDC to small/ring — Vaughan-Jackson) are classic. Treatment focuses on DMARDs, biologics, synovectomy, tendon transfers (EIP to EPL, FDS to EDC), and joint arthrodesis or arthroplasty.

16 Fingertip, Nail Bed & Amputation Injuries Trauma

Fingertip injuries are the most common hand injury seen in the ED. Management depends on tissue loss, bone exposure, and the angle/geometry of the defect.

• Subungual hematoma: trephination (nail drill or heated paperclip) if >50% of the nail surface.
• Nail bed laceration: nail removal, nail bed repair with 6-0 or 7-0 absorbable suture, replacement of the nail or a nonadherent splint in the eponychial fold.
• Fingertip amputation with no bone exposed: healing by secondary intention (occlusive dressing).
• Fingertip amputation with bone exposed: local flap (V-Y Atasoy/Kutler advancement, cross-finger flap, thenar flap, Moberg advancement for thumb).
• Digital replantation: considered for thumb amputation (always attempt), multiple digit amputations, sharp amputations distal to FDS insertion, and in children. Generally not indicated for single-digit proximal to FDS insertion in an adult. Performed under operating microscope with bone fixation, extensor repair, flexor repair, arterial anastomosis, nerve repair, vein anastomosis, and skin closure. Leech therapy may be used for venous congestion.

Stener Lesion (Gamekeeper/Skier Thumb)

Rupture of the ulnar collateral ligament of the thumb MCP, often from a ski pole injury. In a true Stener lesion, the ruptured UCL is displaced superficial to the adductor aponeurosis and cannot heal without surgery. Exam reveals thumb MCP laxity >30° with radial stress (or >15° more than the contralateral side). Treatment is operative repair with a suture anchor.

17 Congenital Hand Anomalies Congenital

Congenital hand differences are classified by the Oberg-Manske-Tonkin (OMT) system, which replaced the older Swanson classification. Common entities:

• Syndactyly: webbing of adjacent digits. Simple (skin only) vs complex (bony fusion). Most commonly between the long and ring fingers. Repaired surgically with zigzag incisions and full-thickness skin grafts, typically around 12–18 months of age.
• Polydactyly: extra digit. Preaxial (thumb) is more common in Caucasians; postaxial (small finger) in people of African descent. Treatment depends on Wassel classification for preaxial thumb duplication.
• Trigger thumb in children: FPL nodule causing fixed IP flexion (Notta node). Often resolves spontaneously by age 2; A1 release for persistent cases.
• Radial club hand / radial longitudinal deficiency, cleft hand, camptodactyly, clinodactyly, macrodactyly, and constriction band syndrome are less common but recognized.

18 Hand Surgery Procedures — A to Z

19 Imaging & Diagnostics

• Plain radiographs: PA, lateral, oblique; dedicated scaphoid view; stress views; clenched fist view for SL gap.
• CT: fracture characterization, occult scaphoid fractures, intra-articular step-off, malunion/nonunion evaluation.
• MRI: TFCC tears, ligament injuries, occult fractures, AVN, tumors, tendon ruptures.
• MR arthrogram: gold standard for TFCC and intrinsic carpal ligament tears.
• Ultrasound: dynamic assessment of trigger fingers, ganglia, foreign bodies, tendon ruptures.
• EMG/NCS: confirm compressive neuropathy diagnosis and severity; typical CTS findings include prolonged distal motor and sensory latencies.
• Fluoroscopy (mini C-arm): intraoperative and in-clinic for reduction confirmation and K-wire placement.
• Bone scan: occult scaphoid fracture when MRI unavailable; complex regional pain syndrome (three-phase bone scan shows periarticular uptake).

Reading a Hand X-Ray

The hand surgeon will dictate in a predictable pattern: bone (cortices, alignment, articular surfaces), joint (congruence, space, subchondral change), soft tissue (swelling, foreign body, gas). Document specific measurements verbatim: "volar tilt -15°, radial inclination 18°, radial height 8 mm, 2 mm articular step-off, comminution of the dorsal rim." Never paraphrase numeric findings. When the surgeon says "positive ulnar variance of 3 mm" or "SL gap of 5 mm on clenched fist view," write the number exactly.

20 Medications You Must Know

21 Classification Systems

All major classifications used in hand surgery are enumerated within their respective condition sections above. Key references include:

• Frykman — distal radius fractures (Section 03)
• Mayo — scaphoid fractures (Section 04)
• Mayfield — perilunate injury progression (Section 05)
• Lichtman — Kienböck disease (Section 05)
• Palmer — TFCC lesions (Section 06)
• Bennett / Rolando — thumb metacarpal base fractures (Section 07)
• Verdan — flexor tendon zones I–V (Section 08)
• Leddy and Packer — jersey finger (Section 08)
• Strickland / Boyes — flexor tendon outcome (Section 08)
• Quinnell / Green — trigger finger (Section 09)
• Seddon / Sunderland — nerve injury (Section 11)
• Eaton-Littler — thumb CMC arthritis (Section 15)
• Wassel — thumb polydactyly (Section 17)
• Oberg-Manske-Tonkin (OMT) — congenital hand differences (Section 17)

22 Physical Exam — The Hand Exam

23 Abbreviations Master List

24 Sample HPI Templates

25 References & Sources

Clinical Practice Guidelines

Landmark Publications

Diagram & Figure Sources