Metacarpal Fractures

High-yield overview

Boxer's Fracture | Rotation vs Angulation | Fight Bites | 10-10-30-50 Rule

18-44%Of all hand fractures

0°Acceptable rotation (NONE)

5°Rotation = 1.5cm fingertip overlap

50°Max angulation for 5th MC (Boxer's)

Critical Must-Knows

Cardinal rule: NO degree of rotation is acceptable - fingers must converge to scaphoid tubercle on flexion without scissoring
10-10-30-50 rule for acceptable neck angulation: 2nd=10°, 3rd=10°, 4th=30°, 5th=50° (increases ulnarly due to CMC mobility)
Interossei cause apex dorsal angulation (head drops volar, shaft points dorsally)
Fight bite (laceration over MCP) = human bite until proven otherwise - Eikenella corrodens - requires formal washout + Augmentin
Shortening causes ~7° of MCP extensor lag per 2mm (Strauch) - tolerance ~5mm before functional loss

Clinical Pearls

"
Jahss manoeuvre: Flex MCP + PIP to 90°, push dorsally on proximal phalanx to reduce neck fracture
"
Why 4th/5th tolerate more angulation? CMC joints have 20-30° flexion-extension arc to compensate
"
X-ray CANNOT assess rotation - must check clinically (nail planes, finger cascade, scissoring)
"
Never suture a fight bite wound tightly - leave open for drainage

Clinical Imaging

Imaging Gallery

Preoperative X-ray of the first fracture event. The X-ray shows the fracture of the fifth metacarpal bone shaft of the left hand (red circle).Credit: Choi JS et al. via Arch Plast Surg via Open-i (NIH) (Open Access (CC BY))

Preoperative X-ray of the second fracture event. The X-ray shows refracture and hole-defects of the fifth metacarpal bone shaft of the left hand (red circle). — Preoperative X-ray of the second fracture event. The X-ray shows refracture and hole-defects of the fifth metacarpal bone shaft of the left hand (red Credit: Choi JS et al. via Arch Plast Surg via Open-i (NIH) (Open Access (CC BY))

(a) X-ray of the hand showing fractures involving the shaft of the 1st and base of the 2nd metacarpal of right hand following a blast injury (b) Postoperative X-ray of same patient showing composite f — (a) X-ray of the hand showing fractures involving the shaft of the 1st and base of the 2nd metacarpal of right hand following a blast injury (b) PostoCredit: Kamath JB et al. via Indian J Orthop via Open-i (NIH) (Open Access (CC BY))

Radiograph demonstrating the adjacent second metacarpal fracture post removal of K-wiresCredit: Loh CY et al. via Indian J Plast Surg via Open-i (NIH) (Open Access (CC BY))

Exam Warning

The cardinal rule of metacarpal fractures: No degree of rotation is acceptable. Fingers must converge to the scaphoid tubercle on flexion. If they cross (scissoring), surgical correction is needed. Angulation is tolerated progressively from radial to ulnar (2nd < 3rd < 4th < 5th) due to CMC mobility. Boxer's fracture can tolerate up to 40-50 degrees neck angulation.

Deforming Forces

Interossei Muscles:

Origin from shafts
Flex MCP, Extend IPJ
In fractures: Flex the distal fragment
Result: Apex Dorsal Angulation (Head drops volar)

Acceptable Angulation (Neck Fractures):

Index (2nd): less than 10-15° (Rigid CMC)
Middle (3rd): less than 10-15° (Rigid CMC)
Ring (4th): less than 30-40° (Mobile CMC)
Little (5th): less than 50-60° (Mobile CMC) - Boxer's

Why the Difference?

4th/5th CMC joints have 20-30° flexion/extension arc
Allows compensation for fixed deformity (pseudoclawing)
2nd/3rd CMC joints are rigid pillars

Key Mnemonics

Mnemonic

10-10-30-50Acceptable Angulation

1	10° Index (2nd): 10 degrees - rigid CMC
2	10° Middle (3rd): 10 degrees - rigid CMC
3	30° Ring (4th): 30 degrees - mobile CMC
4	50° Little (5th): 50 degrees - Boxer's fracture, mobile CMC

1	10° Index (2nd): 10 degrees - rigid CMC	3	30° Ring (4th): 30 degrees - mobile CMC
2	10° Middle (3rd): 10 degrees - rigid CMC	4	50° Little (5th): 50 degrees - Boxer's fracture, mobile CMC

Hook:Increases ulnarly due to mobile CMCs - 1-1-3-5 easy to remember

Mnemonic

ROMISurgical Indications

R	Rotation ANY rotational deformity (cardinal rule) - scissoring
O	Open fracture Open fractures including fight bites
M	Multiple Multiple metacarpal fractures (unstable)
I	Intra-articular Displaced intra-articular fractures (head/base)

R	Rotation ANY rotational deformity (cardinal rule) - scissoring	M	Multiple Multiple metacarpal fractures (unstable)
O	Open fracture Open fractures including fight bites	I	Intra-articular Displaced intra-articular fractures (head/base)

Hook:ROMI goes to theatre - Rotation, Open, Multiple, Intra-articular

Mnemonic

WASHFight Bite Management

W	Washout Formal surgical washout in theatre
A	Augmentin Amoxicillin-clavulanate covers Eikenella + oral flora
S	Stay open Never primarily close - leave wound open
H	History Often false ('cut on glass') - assume bite

W	Washout Formal surgical washout in theatre	S	Stay open Never primarily close - leave wound open
A	Augmentin Amoxicillin-clavulanate covers Eikenella + oral flora	H	History Often false ('cut on glass') - assume bite

Hook:WASH the fight bite properly - don't believe the glass story

Overview & Epidemiology

Metacarpal fractures account for roughly 18-44% of all hand fractures (Kollitz), with the 5th metacarpal neck (Boxer's fracture) being the most common pattern in young males. The cardinal rule is that no degree of rotation is acceptable - fingers must converge to the scaphoid tubercle on flexion without scissoring. Acceptable angulation increases from radial to ulnar (10° for 2nd/3rd, 30° for 4th, 50° for 5th) due to progressive CMC joint mobility. The interossei cause apex dorsal angulation, and any laceration over the MCP joint should be treated as a human "fight bite" requiring washout and antibiotics covering Eikenella corrodens.

Fracture Patterns

Metacarpal Fracture Overview

Epidemiology:

18-44% of all hand fractures (Kollitz review); ~88% involve non-thumb metacarpals
Most common: 5th metacarpal neck (Boxer's fracture)
Peak incidence: Young males (10-29 years)
Common mechanisms: Punch, fall, crush

Key Principles:

Rotation is NEVER acceptable (cardinal rule)
Angulation tolerance increases from radial to ulnar
Mobile 4th/5th CMC joints compensate for apex dorsal angulation

Fracture Location Overview

Location	Pattern	Treatment
Neck	Apex dorsal angulation (Boxer's)	Usually conservative
Shaft	Transverse, oblique, spiral	Assess rotation carefully
Base	Intra-articular (CMC joint)	May need surgery if displaced
Head	Intra-articular (MCP joint)	Often need ORIF

Pathophysiology & Anatomy

Metacarpal Anatomy

Structure:

Five metacarpals (1st = thumb, 2nd-5th = fingers)
Each has head, neck, shaft, and base
2nd and 3rd CMC joints are rigid (fixed pillars)
4th and 5th CMC joints are mobile (20-30° arc)

Key Structures:

Interossei muscles originate from shafts
Extensor tendons run dorsally over MCP joint
Sagittal bands stabilise extensor over metacarpal head

CMC Joint Mobility

Ray	CMC Mobility	Angulation Tolerance
2nd (Index)	Rigid	10-15°
3rd (Middle)	Rigid	10-15°
4th (Ring)	Mobile	30-40°
5th (Little)	Mobile	50-70°

Fracture Types

Classification by Location

Anatomic Classification:

Head fractures (intra-articular MCP)
Neck fractures (most common = Boxer's)
Shaft fractures (transverse, oblique, spiral, comminuted)
Base fractures (intra-articular CMC or extra-articular)

By Fracture Pattern:

Transverse: Prone to angulation, stable in rotation
Oblique: Intermediate stability
Spiral: Prone to rotation and shortening
Comminuted: Unstable, often need surgery

Pattern and Implications

Pattern	Deformity Risk	Fixation Preference
Transverse	Apex dorsal angulation	Plate or IM screws
Oblique (greater than 2x diameter)	Shortening, rotation	Lag screws
Spiral	Rotation, shortening	Lag screws or plate
Comminuted	Shortening, instability	Plate +/- bone graft

Clinical Presentation & Examination

Inspection:

Swelling (dorsal hand)
Loss of knuckle prominence (depressed head)
Rotational Alignment:
1. Ask patient to make a fist
2. Fingertips should all point to Scaphoid Tubercle
3. Look for scissoring/overlap
4. Compare fingernail planes (should be parallel)

Neurovascular:

Sensation (Digital nerves)
Perfusion

Skin:

"Fight Bite": Laceration over MCP joint from tooth
Assume infected human bite (Eikenella corrodens)
Needs washout + antibiotics (Augmentin)

Fight Bites

Any laceration over an MCP joint in a young male is a human bite until proven otherwise. The tooth penetrates the joint capsule in flexion, dragging bacteria in. When the finger extends, the tract seals. These require formal washout (often in theatre) and antibiotics covering Eikenella.

Clinical Context: Never suture a fight bite wound tightly.

Conservative Management

metacarpal fractures management algorithm — Management algorithm for metacarpal fracturesCredit: OrthoVellum

Indications:

Stable fractures
Acceptable angulation
No rotation

Technique:

Buddy Strapping: For stable shaft fractures
Ulnar Gutter Splint: For 4th/5th Metacarpal
Radial Gutter Splint: For 2nd/3rd Metacarpal
Position of Safety (Not for fractures!): Intrinsic plus position usually used for immobilisation, BUT:
- Some evidence suggests buddy taping alone allows earlier return to work for Boxer's fractures.

Duration:

3-4 weeks immobilisation
X-ray check at 1 week for position

Investigations & Radiographic Assessment

Imaging Assessment

Plain Radiographs:

PA (posteroanterior) of hand
Lateral of hand
Oblique of hand
Assess all 5 metacarpals systematically

What to Assess:

Fracture location (head, neck, shaft, base)
Angulation (apex dorsal = most common)
Shortening (compare to adjacent metacarpal)
Rotation (cannot assess on X-ray - clinical only)

Boxer's fracture - 5th metacarpal neck fracture on X-ray — Oblique hand X-ray demonstrating a classic boxer's fracture - a 5th metacarpal neck fracture (circled). This is the most common metacarpal fracture pattern, typically occurring from striking with a closed fist. Note the apex dorsal angulation at the fracture site. Up to 50 degrees of angulation is acceptable for 5th metacarpal neck fractures due to compensatory CMC joint mobility.Credit: PMC - CC BY 4.0

Special Views

View	Indication	What It Shows
Brewerton	MCP collateral ligament injury	Collateral ligament avulsions
Skyline	Metacarpal head assessment	Articular surface fractures
CT scan	Complex base fractures	CMC joint involvement

Treatment Algorithm

Conservative Indications:

Stable fractures with acceptable angulation
No rotational deformity
Closed injury (no fight bite)

Conservative Techniques:

Buddy taping: Simple, allows early motion
Ulnar gutter splint: 4th/5th metacarpal
Radial gutter splint: 2nd/3rd metacarpal
Duration: 3-4 weeks

Surgical Indications:

ANY rotational deformity (cardinal rule)
Unacceptable angulation for the ray
Shortening greater than 5mm
Open fractures
Multiple metacarpal fractures
Intra-articular displacement

Treatment by Pattern

Pattern	First-Line	Surgical Option
Boxer's (acceptable)	Buddy tape or ulnar gutter	Rarely needed
Shaft with rotation	Surgery indicated	K-wires or plate
Head fracture	Often surgery	Lag screws or plate
Base (CMC)	Assess stability	K-wires or ORIF

Surgical Management

Indications:

Rotational deformity (ANY)
Unacceptable angulation (e.g., greater than 50° in 5th neck)
Shortening greater than 5mm (relative)
Open fractures
Multiple metacarpal fractures
Intra-articular displacement

Techniques:

K-wire Fixation:
- Retrograde (intramedullary) or Transverse (pinning to adjacent bone)
- Minimally invasive, wire removal later
ORIF (Plate/Screws):
- For shaft fractures, unstable patterns
- Anatomical reduction
- Risk: Tendon adhesions, prominent hardware
Intramedullary Screw:
- Newer technique for neck/shaft
- Headless compression screw

Differential Diagnosis

The dorsal hand injury is rarely a true diagnostic dilemma, but the exam tests whether you can separate the metacarpal fracture from look-alikes that change management.

Differentiating Dorsal Hand / Knuckle Injuries

Diagnosis	Distinguishing features	Why it matters
5th metacarpal neck (Boxer's)	Apex-dorsal angulation, lost knuckle prominence, punch mechanism	Usually conservative; high angulation tolerance
Fight bite / septic MCP	Laceration over MCP, often a denied bite, joint signs/pus	Surgical emergency: washout, never close
Bennett / Rolando (thumb base)	Thumb CMC pain, intra-articular base fracture-dislocation	Needs anatomic reduction +/- fixation
Reverse (baby) Bennett (5th base)	5th CMC, base displaced by ECU pull	Often unstable - pinning/ORIF
CMC fracture-dislocation	Carpometacarpal step-off, missed on PA, seen on lateral/oblique	Easily overlooked; needs reduction
Sagittal band rupture (boxer's knuckle)	Extensor subluxation, no fracture on X-ray, painful MCP	Soft-tissue injury - splint vs repair, not a fracture
Phalangeal / proximal phalanx fracture	Tenderness distal to MCP, finger-level deformity	Different alignment and rehab principles

Controversies & Areas of Uncertainty

Angulation thresholds are eminence-based, not evidence-based. The widely quoted 10-10-30-50 (or 10-20-30-40) figures vary between texts; the Cochrane review (Poolman) found no high-quality data defining a precise cut-off, and many patients tolerate angulation well beyond classic limits with good function.
Best non-operative method is unsettled. Poolman found no regimen (buddy taping, soft wrap, ulnar gutter, functional brace) superior to another. Practice varies from immediate mobilisation to 3-4 weeks of splinting.
IM screw vs K-wire vs plate. Antegrade headless IM screws give excellent union and motion (Beck), but evidence is largely Level III-IV; concerns include articular cartilage violation at the entry point and cost. No adequately powered RCT defines the optimal implant.
Shortening tolerance. Strauch quantifies ~7° extensor lag per 2 mm shortening, but the clinically "acceptable" limit (commonly cited as ~5 mm) is extrapolated, and MCP hyperextension may compensate.
Fight-bite antibiotic duration and washout setting. Universal agreement on washout plus amoxicillin-clavulanate, but optimal antibiotic duration and whether minor early injuries can be managed without theatre remain debated.

Conservative Treatment of Fifth Metacarpal Neck Fractures (Cochrane)

Poolman RW, Goslings JC, Lee JB, et al. • Cochrane Database Syst Rev (2005)

Key Findings:

Five randomised/quasi-randomised trials, 252 participants, comparing functional treatment with immobilisation
No single non-operative regimen was statistically superior to another in result
Trials were of limited quality and size; validated hand function was not reported in any study

Clinical Implication: For closed fifth metacarpal neck (Boxer's) fractures there is no proven advantage of one non-operative method over another, so the simplest functional treatment (buddy taping/early motion) is reasonable.

Verify on PubMed (PMID 16034891)

Rotational Deformity Following Metacarpal Fracture

Royle SG • J Hand Surg Br (1990)

Key Findings:

Prospective series of 91 patients with 98 metacarpal fractures
A quarter had minor rotation under 10 degrees; only 5 had more, and just 2 needed operative correction for rotational instability
Rotation must be assessed with an end-on view of the fingernail, as MCP joint motion is often restricted after fracture

Clinical Implication: Clinically significant malrotation is uncommon but must be actively sought (nail-plate / finger-cascade exam), because it is the deformity least tolerated and the main operative indication.

Verify on PubMed (PMID 2307874)

Effect of Metacarpal Shortening on the Extensor Mechanism

Strauch RJ, Rosenwasser MP, Lunt JG • J Hand Surg Am (1998)

Key Findings:

Cadaver model (9 hands), 2nd and 5th metacarpal shaft fractures shortened in 2 mm increments to 10 mm
Average of 7 degrees of MCP extensor lag produced for every 2 mm of metacarpal shortening
MCP hyperextension capacity may clinically compensate for some of this lag

Clinical Implication: Quantifies the shortening tolerance rule: roughly 7 degrees of extensor lag per 2 mm shortening, supporting fixation when shortening approaches 5 mm or more.

Verify on PubMed (PMID 9620194)

Human Bite Wounds and Eikenella corrodens

Griego RD, Rosen T, Orengo IF, Wolf JE • J Am Acad Dermatol (1995)

Key Findings:

Clenched-fist (fight-bite) injuries to the hand carry far higher infection and complication rates than bites elsewhere
Infections are polymicrobial; Eikenella corrodens is the characteristic pathogen of human bites
Hand bites warrant aggressive irrigation/debridement and beta-lactam plus beta-lactamase-inhibitor cover

Clinical Implication: A laceration over the MCP joint is a fight bite until proven otherwise - it needs washout and amoxicillin-clavulanate, and must never be primarily closed.

Verify on PubMed (PMID 7490347)

Intramedullary Screw Fixation of Metacarpal Fractures

Beck CM, Horesh E, Taub PJ • Plast Reconstr Surg (2019)

Key Findings:

Systematic review of 9 studies, 169 metacarpal fractures (74% small finger; mostly neck fractures)
Radiographic union in 100% of reported cases; mean MCP flexion 86 degrees and grip 96% of contralateral
No serious complications; only minor complications including asymptomatic hardware removal

Clinical Implication: Antegrade headless intramedullary screw fixation is a safe, low-morbidity alternative to K-wires for neck and shaft fractures needing surgery, allowing early motion without routine hardware removal.

Verify on PubMed (PMID 30676504)

Metacarpal Fractures: Treatment and Complications

Kollitz KM, Hammert WC, Vedder NB, Huang JI • Hand (NY) (2014)

Key Findings:

Metacarpal fractures comprise 18-44% of all hand fractures; the fifth finger is most commonly involved
Around 88% of metacarpal fractures involve the non-thumb metacarpals; most are simple, closed and stable
Persistent controversy and limited high-level evidence to define the optimal treatment algorithm

Clinical Implication: Most metacarpal fractures unite well non-operatively; surgery is reserved for rotation, unacceptable angulation/shortening, open/multiple fractures and displaced intra-articular patterns.

Verify on PubMed (PMID 24570632)

Complications

Complications of Metacarpal Fractures

Complication Pitfalls

Rotational malunion: every 5° of rotation at the metacarpal produces ~1.5cm of fingertip overlap; correct with a dorsal-approach derotation osteotomy and plate fixation. Stiffness from tendon adhesions is the most common post-surgical complication - mitigate with stable fixation and early protected motion. Hardware issues: dorsal plates cause adhesions/prominence, K-wires cause pin-site infection and migration.

Postoperative Care

Rehabilitation Protocol

Immobilisation Phase (0-3 weeks):

Splint protection (ulnar or radial gutter)
Elevation to reduce swelling
Active finger ROM if fixation stable
Avoid heavy loading

Mobilisation Phase (3-6 weeks):

K-wire removal at 4-6 weeks
Wean from splint
Active ROM exercises
Hand therapy referral

Strengthening Phase (6-12 weeks):

Progressive grip strengthening
Return to light activities
Functional exercises

Timeline by Treatment

Treatment	Immobilisation	Return to Work
Buddy taping	Immediate ROM	1-2 weeks light duties
Splinting	3-4 weeks	4-6 weeks
K-wires	4-6 weeks to removal	6-8 weeks
ORIF plate	1-2 weeks splint	8-12 weeks manual

Outcomes

Functional Outcomes

Overall:

Excellent outcomes for most metacarpal fractures
95% union rate with appropriate treatment
Stiffness is main complication, especially after surgery

Boxer's Fracture:

Excellent function even with radiographic malunion
Loss of knuckle prominence is cosmetic only
Surgery not superior to conservative for typical patterns

Shaft Fractures:

Good outcomes if rotation corrected
Stiffness risk higher with plate fixation
K-wires associated with less stiffness but less rigid fixation

Outcome by Pattern

Pattern	Union Rate	Main Concern
Boxer's (conservative)	Greater than 95%	Cosmetic only
Shaft (K-wire)	Greater than 95%	Pin complications
Shaft (plate)	Greater than 95%	Stiffness, adhesions
Head fracture	90-95%	MCP arthritis

Evidence Base

Key Studies

Cochrane Review (Poolman 2005):

Conservative treatment effective for Boxer's fractures
No difference between immobilisation methods
Surgery adds risk without clear benefit for standard patterns

Biomechanical Studies:

Rotation tolerance: Zero degrees acceptable
5° rotation = 1.5cm fingertip overlap
Shortening greater than 5mm causes extensor lag

Evidence Summary

Study	Key Finding	Clinical Impact
Poolman 2005	Conservative = surgical for Boxer's	Avoid unnecessary surgery
Ali 2005	K-wire biomechanics effective	K-wires are reasonable fixation
Kollitz 2014	Review of treatment options	Algorithm-based approach

Exam Viva Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

Scenario 1: Boxer's Fracture

CLINICAL PROMPT

"A 22-year-old rugby player presents with a swollen right hand after punching a wall. X-ray shows a 5th metacarpal neck fracture with 40 degrees of volar angulation. There is no rotational deformity clinically. How do you manage this?"

PRACTICAL APPROACH

This is a classic **Boxer's Fracture**. **Classification:** 5th Metacarpal Neck fracture. **Decision Making:** - Angulation is 40°. Limit for 5th ray is often cited as 40-70°. - CMC joint of little finger is mobile (20-30°), allowing compensation. - No rotation (Critical finding). - Assuming no open wound ("fight bite"). **Management Plan:** - **Conservative Treatment** is appropriate. - **Why?** Functional outcomes are excellent despite radiographic deformity. Surgery introduces risks (stiffness, infection, hardware). - **Technique:** Ulnar gutter splint or just buddy strapping (to ring finger) to allow early motion. - Evidence (Poolman et al.) supports functional treatment. **Follow-up:** - Check X-ray at 1 week (ensure no further slip). - Mobilise out of splint at 3-4 weeks. - Warn about: Loss of knuckle prominence (cosmetic), bump in palm. **When I would operate:** - If angulation greater than 70° (severe pseudoclawing risk). - If ANY rotation developed. - If open fracture.

KEY CLINICAL POINTS

5th ray tolerates significant angulation (mobile CMC)

Rotation is the main indication for surgery

Loss of knuckle is expected cosmetic outcome

Always assume punched a 'tooth' (check for wounds)

COMMON PITFALLS

Operating purely for X-ray appearance

Missing a fight bite

Missing malrotation (scissoring)

FURTHER QUESTIONS

"How does the management differ for the 2nd metacarpal?"

"What is the Jahss manoeuvre?"

"What is the maximum acceptable shortening?"

CLINICAL SCENARIOChallenging

Scenario 2: Third Metacarpal Shaft Fracture with Rotation

CLINICAL PROMPT

"A 30-year-old presents 5 days after a fall onto his hand. X-rays show a short oblique fracture of the third metacarpal shaft with minimal displacement and approximately 15 degrees of apex dorsal angulation. However, on clinical examination, when he makes a fist, you notice that the middle finger crosses over the index finger and the fingernail plane is rotated compared to the adjacent fingers. What is your management?"

PRACTICAL APPROACH

This scenario illustrates the cardinal rule of metacarpal fractures: any degree of rotational deformity is unacceptable and requires surgical correction. Although the angulation of 15 degrees is within acceptable limits for the third metacarpal (rigid CMC joint allows up to 15 degrees), the rotational malalignment causing scissoring is not tolerable and will significantly impair hand function, causing weak grip and inability to fully flex the fingers without overlap. My management would be surgical fixation. I would first explain to the patient that while some fractures can be treated with splinting, the rotation in his finger means the bones are twisted and will not heal in a functional position without surgery. At surgery, I would use an open approach to the third metacarpal shaft - typically a dorsal longitudinal incision between the second and third metacarpals, reflecting the extensor tendons radially or ulnarly. I would reduce the fracture correcting both the angulation and the rotation - this is where the surgery becomes technically demanding because you must ensure the nail plane is correct and the finger points to the scaphoid tubercle when checking alignment intraoperatively. For fixation of this short oblique fracture, I would use either a dorsal plate (2.0 or 2.3mm) with at least 3 screws each side of the fracture, or if the obliquity is favorable, I could use lag screws alone (2 or 3) perpendicular to the fracture line. Post-operatively, I would use a short period of splinting (1-2 weeks) for comfort, then start early protected motion to prevent tendon adhesions which are a significant risk with dorsal plating. I would warn him about risks including stiffness (most common), prominent hardware potentially requiring later removal, infection, and incomplete correction of rotation.

KEY CLINICAL POINTS

ANY rotational deformity requires surgical correction (cardinal rule)

Clinical assessment (finger cascade, scissoring) more important than X-ray

Third metacarpal rigid CMC allows only 10-15° angulation

ORIF with plate or lag screws, must correct rotation intraoperatively

Stiffness from tendon adhesions is main complication of dorsal plating

COMMON PITFALLS

Accepting rotational deformity because angulation is acceptable

Attempting closed reduction and K-wires (will not maintain rotation correction)

Not checking rotational alignment intraoperatively

Prolonged immobilization causing stiffness

FURTHER QUESTIONS

"How do you assess rotational alignment intraoperatively?"

"What is the biomechanical advantage of lag screws in oblique fractures?"

"How much fingertip overlap results from 5 degrees of rotation?"

CLINICAL SCENARIOCritical

Scenario 3: Fight Bite with Septic Arthritis

CLINICAL PROMPT

"A 24-year-old presents to the emergency department 3 days after 'cutting his hand on glass' at a bar. He has a 1cm laceration over the dorsum of his right 3rd MCP joint that he cleaned himself. The wound now has purulent discharge, the MCP joint is swollen and erythematous, and he has pain and restricted motion. He is febrile at 38.5 degrees. X-rays show soft tissue swelling but no fracture or gas. What is your assessment and management?"

PRACTICAL APPROACH

This is a fight bite with septic arthritis of the MCP joint until proven otherwise. The story of 'cutting on glass' is a classic cover story - any laceration over an MCP joint in a young person presenting from a bar should be assumed to be from punching someone in the teeth. The mechanism is that when the fist impacts the teeth, the tooth penetrates the extensor tendon and MCP joint capsule while the MCP is flexed. When the finger extends, the tract closes, sealing bacteria (particularly Eikenella corrodens and oral anaerobes) deep in the joint. The 3-day delay and current presentation with fever, purulent drainage, and joint signs indicate established septic arthritis which is a surgical emergency. My immediate management would be IV antibiotics - I would use amoxicillin-clavulanate (Augmentin) which covers Eikenella, Streptococcus, Staphylococcus, and anaerobes. I would take him urgently to theatre for formal open washout of the MCP joint. Under general or regional anesthesia, I would extend the laceration longitudinally, inspect the extensor tendon (often lacerated or frayed), open the MCP joint capsule widely, and perform copious irrigation with several liters of saline. I would inspect the metacarpal head for cartilage damage and debride any devitalized tissue. Critically, I would leave the wound open - primary closure of a fight bite is contraindicated as it creates an abscess. I would dress it with wet-to-dry dressings and plan for delayed primary closure or healing by secondary intention. Post-operatively, he needs IV antibiotics for 48-72 hours minimum, then transition to oral Augmentin for a total of 2 weeks. I would also send wound swabs and joint fluid for culture, though these are often negative. If there is significant tendon damage, he may need delayed tendon repair or reconstruction. I would counsel him honestly that he likely punched someone, this is serious, and if not properly treated he could lose function of his finger or develop chronic osteomyelitis requiring further surgery.

KEY CLINICAL POINTS

Laceration over MCP = fight bite until proven otherwise

Eikenella corrodens and oral flora cause rapidly progressive infection

Septic arthritis requires urgent surgical washout, not just antibiotics

NEVER primarily close a fight bite wound

Amoxicillin-clavulanate (Augmentin) is antibiotic of choice

COMMON PITFALLS

Accepting 'cut on glass' story and treating as simple laceration

Treating with oral antibiotics alone without washout

Primary closure of the wound (creates abscess)

Not inspecting extensor tendon and joint capsule

FURTHER QUESTIONS

"What organisms are typically involved in fight bites?"

"Why is Eikenella corrodens particularly concerning?"

"What would you do if the patient refuses to admit punching someone?"

MCQ Practice Points

Clinical Pearl

Q: What is the maximum acceptable angulation for a fifth metacarpal neck fracture (boxer's fracture) treated non-operatively?

A: Up to 70 degrees of apex dorsal angulation is acceptable for fifth metacarpal neck fractures due to the compensatory motion at the 4th and 5th CMC joints (30-40 degrees of flexion-extension). The fourth metacarpal accepts up to 40 degrees, the third metacarpal 15 degrees, and the second metacarpal (index) only 10-15 degrees because the 2nd and 3rd CMC joints have minimal motion. Rotational deformity is never acceptable and always requires correction.

Clinical Pearl

Q: What is the indication for surgical fixation of metacarpal shaft fractures?

A: Surgical indications include: Rotational malrotation (any degree - clinical scissoring), angulation exceeding acceptable limits (varies by ray), multiple metacarpal fractures, open fractures, intra-articular fractures with displacement, and shortening greater than 5mm (causes extensor lag). Spiral fractures are prone to rotational deformity while transverse fractures are prone to angular deformity. Lag screws are ideal for long oblique/spiral patterns; plates for transverse/short oblique/comminuted patterns.

Clinical Pearl

Q: How do you clinically assess for rotational malalignment in metacarpal fractures?

A: Finger cascade test: With the MCP joints flexed, all fingers should point toward the scaphoid tubercle. Scissoring: Overlapping of fingers during flexion indicates malrotation. Each 5 degrees of rotational deformity at the metacarpal level results in approximately 1.5cm of digital overlap at the fingertip. Compare tenodesis effect (passive wrist extension causes finger flexion) to the contralateral hand. Rotational deformity is the most poorly tolerated malunion and requires correction.

Clinical Pearl

Q: What is the difference between a Bennett's fracture and a Rolando's fracture?

A: Bennett's fracture: Intra-articular fracture-dislocation at the thumb CMC joint with a single volar-ulnar fragment attached to the AOL while the metacarpal shaft subluxates radially and proximally due to APL pull. Rolando's fracture: Comminuted intra-articular fracture at the same location with T or Y pattern (at least 3 fragments). Both require anatomic reduction. Bennett's is typically fixed with K-wires or screw, while Rolando's may need plate fixation or external fixation for severe comminution.

Clinical Pearl

Q: What is the reverse Bennett fracture and how is it managed?

A: Reverse Bennett fracture is an intra-articular fracture-dislocation at the fifth CMC joint with a volar-ulnar fragment remaining attached to the hamate while the metacarpal base displaces dorsally and proximally (pulled by ECU). Also called a baby Bennett. Treatment follows similar principles to thumb Bennett's: closed reduction and percutaneous pinning if anatomic reduction achieved, or ORIF for irreducible or significantly displaced fractures. Maintain reduction with splinting in slight flexion.

Guidelines, Registries & Global Practice

Global Epidemiology

Metacarpal fractures are 18-44% of all hand fractures; the hand accounts for ~20% of all skeletal fractures presenting to emergency departments worldwide.
Strong young-male preponderance (peak 10-29 years), reflecting interpersonal violence/punch and sports mechanisms; an alcohol-related, weekend, urban pattern is reported across high- and middle-income settings.
The fifth metacarpal neck (Boxer's fracture) is the single most common pattern; non-thumb metacarpals comprise ~88% of metacarpal fractures.

Society Guidance / Consensus (side by side)

Body	Position on Boxer's & shaft fractures	Emphasis
AAOS / ASSH (US)	Non-operative for most isolated closed neck/shaft fractures with acceptable alignment	Rotation and intra-articular displacement drive surgery
BOA / BSSH (UK)	Functional treatment and early motion for stable Boxer's fractures	Avoid over-immobilisation; hand-therapy access
AO Foundation	Operative options (lag screw, plate, antegrade IM nail/screw) defined by pattern and stability	Anatomic reduction of rotation; absolute vs relative stability
EFORT / European consensus	Conservative-first; IM techniques increasingly favoured when fixation needed	Minimise stiffness, early rehabilitation

There is broad international agreement (and no major guideline disagreement) on the core principles: zero tolerance of rotation, ray-dependent angulation thresholds, and conservative-first management of stable fractures. Differences are largely in surgical technique preference rather than indications.