Green's Metacarpal Phalanx Dislocations

Front 1

What is the most common ligamentous hand injury?

Back 1

PIPJ dislocation

Front 2

What is the normal range of motion of the PIP joint?

Back 2

100-110 degrees

Front 3

How does the PIP joint gain 9 degrees of supination through its arc of motion?

Back 3

Via asymmetry of the condyles

Front 4

What are the origins and insertions of the collateral ligaments of the PIP joints?

Back 4

2-3 mm thick, both arise from concave fossa on lateral aspect of each condyle, pass obliquely and volarly. Proper: inserts on volar third of base of middle phalanx. Accessory: inserts on volar plate.

Front 5

What is the primary restraint to radial and ulnar deviation in the PIP joint?

Back 5

Collateral ligaments (proper and accessory)

Front 6

Where is the volar plate most densely attached?

Back 6

At lateral margins, where it is confluent with insertion of collateral ligament; thinner centrally.

Front 7

What are the volar check ligaments?

Back 7

Originate from periosteum of proximal phalanx, inside A2 pulley. Paired, cordlike structures on lateral sides of volar plate, prevent hyperextension of joint while permitting full flexion.

Front 8

What is the "ligament-box" configuration of the PIPJ? When does instability occur?

Back 8

Ligament box: paired collateral ligaments and volar plate. Disruption in two planes results in instability/displacement of middle phalanx.

Front 9

At what location do the collateral ligaments tend to fail? The volar plate?

Back 9

Collaterals fail PROXIMALLY, while volar plate tends to avulse DISTALLY.

Front 10

What clinical observation ultimately determines treatment of an injured PIP joint?

Back 10

Maintenance of joint reduction with active motion. Do active ROM first, if that is stale, put through passive range, with gentle stress on each collateral in full extension and 30 degrees of flexion, and shearing volar and dorsally for dorsovolar stability. Full ROM means brief immobilization only with early protected ROM.

Front 11

What are the three directions of PIPJ dislocation?

Back 11

Dorsal, lateral, and volar (refers to position of middle phalanx)

Front 12

What is the typical mechanism of dorsal PIP dislocation?

Back 12

Hyperextension with axial loading, eg tip of digit hit with ball in sports

Front 13

What are three types of dorsal PIP dislocation? What is the implication for treatment?

Back 13

1. Hyperextension: avulsion of volar plate, minor longitudinal split in collateral ligaments
2. Dorsal dislocation: Avulsion of volar plate with major split in collaterals, "bayonet" positioning
3. Fracture-dislocation: shear on volar base of middle phalanx. Stable or unstable.

Types 1 and 2 usually conservative mgmt
Type 3 may require surgical treatment

Front 14

Describe the pathology of stable vs unstable dorsal PIP fracture-dislocations.

Back 14

Stable: fracture-dislocation with small triangular fragment representing <40% of volar articular arc. Dorsal collaterals remain attached, giving stability.

Unstable: >40% of volar articular surface disrupted, meaning collateral ligament-volar plate complex attached to fragment, not middle phalanx. Closed red difficult; may need open reduction.

Front 15

What is the mechanism of a PIP pilon fracture? Are these treated conservatively or aggressively?

Back 15

Axial compressive force with proximal and middle phalanges in line. Aggressive treatment may prevent deformity, stiffness, and arthritis.

Front 16

What is the treatment of stable type 1 (hyperextension) PIP injuries?

Back 16

Reassure patient that most return to normal function, but swelling/stiffness may persist for months. Immobilize for comfort <1 week - problems from prolonged immobilization are more likely than problems from mobilizing too early!

Front 17

What is the treatment of stable type 2 (dorsal dislocation) PIP injuries?

Back 17

Require 2-3 weeks of immobilization or controlled movement - will likely return to normal.

Front 18

What is the treatment of stable type 3 (fracture-dislocation) PIP injuries?

Back 18

If truly stable, can treat with 3 weeks dorsal block splinting followed by ROM. Most require formal hand therapy to avoid long term stiffness and disuse.

Front 19

What are some options for treatment of unstable PIP fracture-dislocations?

Back 19

Dynamic skeletal traction
Extension block splinting/pinning
Transarticular pinning
ORIF
Volar plate arthroplasty

Front 20

What principle allows reduction of fracture fragments in a PIP fracture-dislocation held by skeletal traction?

Back 20

Ligamentotaxis.

Front 21

What type of PIP fracture-dislocations is ORIF appropriate for?

Back 21

Acute cases with a single, large fragment - anatomic restoration of articular surface is difficult even with a large, single fragment

Front 22

What are some operative treatment options for unstable PIP fracture dislocations?

Back 22

Kwiring, ORIF, hemihamate autograft, cerclage wiring, volar plate arthroplasty

Front 23

What are characteristics of a fracture-dislocation (PIP) suitable for volar plate arthroplasty?

Back 23

Unstable, >40% articular surface involved, unsuitable for ORIF

Front 24

What is the exposure and operative basics for volar plate arthroplasty in PIP fracture-dislocation?

Back 24

Volar approach with chevron incision
"Shotgun" joint after proper collateral excision
Depending on length of time after injury, may need to step-cut and partially release checkrein ligaments to advance volar plate
Advance plate with pull-out suture, thread through drill holes in middle phalanx with PIPJ in 30 degrees flexion (to avoid tethering extensors)
Second suture between lateral volar plate and collaterals
Kwire joint at 30 degrees x2-3 weeks

Front 25

What types of dorsal fracture-dislocations are amenable to extension block splinting?

Back 25

Congruent joint postreduction, articular involvement <40%

Front 26

Describe the dynamic skeletal traction method described by the author for unstable, comminuted PIP fracture-dislocations.

Back 26

Use long 0.045" K-wires
First wire through proximal phalangeal condyles (centre of rotation)
Second wire through condyles of middle phalanx
Third wire in middle phalanx (fulcrum)
2.5cm between ends of kwires bent into hooks
Traction maintained with dental elastics

Front 27

What are treatment options for a neglected or chronic PIP fracture-dislocation?

Back 27

1. Open reduction with corrective osteotomy, +/- bone graft (need good reduction and reasonable chondral surfaces)
2. Implant arthroplasty
3. Arthrodesis
4. Volar plate arthroplasty
5. Hemihamate arthroplasty

Front 28

How does one evaluate the patient presenting with an apparent chronic PIPJ subluxation/hyperextension? What are two possibilities in this presentation that must be ruled out?

Back 28

1. Compare vs opposite side to rule out baseline laxity
2. If swan neck, distinguish primary volar plate laxity from extensor imbalance (eg severe mallet finger) - test by holding PIP in full extension and testing extension of DIP

Front 29

What treatments are available for symptomatic chronic hyperextension deformities of the PIP?

Back 29

1. Nonoperative: figure of eight ring splints, dorsal extension-block splinting
2. Surgical: late reattachment or reconstruction of volar plate (lateral band, slip of FDS, accessory collaterals)

Front 30

Describe the technique of chronic symptomatic PIP hyperextension/swan neck using lateral band transposition.

Back 30

1. Ulnar-sided mid-lateral incision made from 1cm proximal to 1cm distal to PIPJ
2. Incise Cleland's, protect NVB palmarly
3. Free lateral band from dorsal margin, keep intact proximal and distal, mobilize palmar to PIPJ
4. Flex PIPJ 20-30 degrees, suture lateral band to edge of A3 pulley, or open pulley and suture lateral band into it.
5. Apply dorsal extension block splint in 10-20 degrees flexion

Front 31

What are three requirements for successful treatment of a flexion contracture?

Back 31

1. Nonarthritic joint
2. Functional extensor mechanism
3. Motivated/compliant patient

Front 32

Is there a risk of instability following excision of volar plate and collaterals for PIP flexion contracture?

Back 32

No - joint should lay flat on the table at the end of surgery

Front 33

In what directions does the DIP joint tend to dislocate?

Back 33

Dorsal or lateral
Usually associated with open wound

Front 34

What directional forces are the MCPJs of the fingers vulnerable to?

Back 34

Forces directly ulnarly and dorsally

Front 35

Describe the capsule and supporting structures of the MCP joint.

Back 35

Capsule: extends from metacarpal neck to base of proximal phalanx
Dorsally: loose areolar tissue, insertion of common extensor tendon
Volarly: volar plate (continuous with deep transverse metacarpal ligament)
No checkreins in MCP!
Laterally: collateral ligaments

Front 36

How common are dorsal MCP dislocations? What digits tend to suffer?

Back 36

Uncommon injury
Most frequently involved: index, then small (border digits)

Front 37

What is the usual mechanism of dorsal MCPJ dislocations?

Back 37

Hyperextension with FOOSH

Front 38

What is the mechanism by which some MCPJ dislocations are irreducible?

Back 38

Volar plate is drawn distally over metacarpal head; periarticular tendons (flexors, lumbricals) drawn dorsally and proximally past MC head. This forms a tendon "noose". In small finger, entrapping structures include cmomon tendon of ADM and FDM

Front 39

How should a simple, subluxed MCPJ be reduced?

Back 39

Do NOT apply hyperextension or traction, as this will draw the volar plate into the joint and prevent reduction. Flex wrist to relax flexors, apply distal and volar directed pressure to base of proximal phalanx. Apply dorsal extension block splint to prevent extension beyond neutral.

Front 40

What is the posture of a complete MCPJ dorsal dislocation? Contrast with a subluxed MCPJ.

Back 40

MCPJ held in slight extension, flexion impossible
PIP and DIP in slight flexion
Digit midly deviated towards central digits
Prominence felt in palm, hollow palpated dorsally proximal to base of proximal phalanx

In a subluxed MCPJ, the finger is hyperextended.

Front 41

What is a Brewerton view?

Back 41

Hand placed palm up, dorsum of MCPJs against plate, MCPJs flexed 65 degrees, beam tilted 15 degrees ulnar to radial.
Used to detect occult MCP head fractures

Front 42

What is the treatment of an irreducible MCPJ dorsal dislocation?

Back 42

Surgical: dorsal or volar, combined approach also

Front 43

Describe Green's volar approach to a dorsal MCPJ dislocation. What structure is tented up directly beneath the skin?

Back 43

Exposure: Oblique palmar incision between proximal and distal palmar creases, to radial mid-axial line
-> Radial NVB is usually tented over protruding index MCP head, just beneath skin (ulnar NVB in D5)
- Metacarpal head will be obvious in subcutaneous tissue
- Release A1 pulley to release tension applied by flexor tendon

Front 44

What is the usual presentation of an isolated MCPJ radial collateral ligament tear? Mechanism of injury?

Back 44

Athlete with "jammed finger", pain and swelling not improving, tender and unstable along radial side. Often secondary to forced ulnar deviation with MCPJ flexed.

Front 45

What is the grading and treatment of isolated MCPJ radial collateral ligament tear?

Back 45

Depends on grade.
Grade 1: pain without laxity
Grade 2: laxity with endpoint in 60 deg flexion
Grade 3: no endpoint
Grade 1 and 2: splinting alone
Grade 3: 4 weeks casting in radial deviation or surgical repair

Front 46

What is the treatment of a subacute or chronic complete RCL injury?

Back 46

Unlikely to improve on its own - requires surgical ligament repair with bone anchor

Front 47

What are the two common mechanisms of a locked MCPJ? What must it be differentiated from?

Back 47

Differentiate from trigger digit (can't extend any IPJs)

Usual causes:
1. Restriction of collateral ligament excursion by prominent MCP head condyle
2. Impalement of ligament on marginal degenerative osteophyte

Front 48

How may a locked MCPJ be resolved?

Back 48

Insufflate joint with 2mL NS
Flex joint
Radially deviate and externally rotate digit
Extend digit
Splint in extension x1 week

Front 49

Which joint of the body has the most variable range of motion? Why?

Back 49

Thumb MP joint, due to different radii of curvature of metacarpal heads
Lower range of motion may be associated with increased frequency of joint injury!

Front 50

Does the UCL of the thumb tend to tear distally or proximally?

Back 50

Distally, at its insertion.

Front 51

What is the most common fracture pattern associated with UCL injury?

Back 51

Avulsion fracture of ulnar base of proximal phalanx at insertion of ligament

Front 52

What are criteria for closed vs open treatment of an avulsion fracture of ulnar base of thumb proximal phalanx associated with UCL tear?

Back 52

<10% of articular surface
>2mm displacement

Smaller fractures may be casted but may also eventually require ORIF due to persistent pain

Front 53

What is a Stener lesion?

Back 53

Interposition of the adductor aponeurosis between distally avulsed ligament and insertion into base of proximal phalanx

Front 54

In what position is the UCL of the thumb best tested? Why?

Back 54

In flexion, as this is the point of maximum tension, and also because the volar plate provides lateral stability in full extension of the thumb.

Front 55

How does one differentiate between partial and complete ruptures of the thumb UCL on exam?

Back 55

Difficult to distinguish absolutely
Some use degree criteria
Some use absence of endpoint to valgus stress
Stress XR not necessarily helpful

Front 56

Define gamekeeper's thumb.

Back 56

Chronic instability of UCL

Front 57

Treatment for acute partial ruptures of UCL?

Back 57

4 week period of immobilization in thumb spica (IP free), then 2 week active ROM

Front 58

Treatment of complete rupture of thumb UCL?

Back 58

Operative intervention usually attempted. If treating conservatively, must R/O Stener lesion.

Front 59

What techniques may be used to repair a complete UCL tear?

Back 59

Usually avulsed at insertion, requiring a pull-out suture or bone anchor to reattach to bony insertion. May be done arthroscopically.

Front 60

What is the most common complication of thumb UCL repair?

Back 60

Neurapraxia of dorsal sensory branches of radial nerve due to traction during procedure - may last weeks

Front 61

How do patients with chronic UCL instability present? Do they tend to have partial or complete UCL tears?

Back 61

Present with pain, swelling, weakness of thumb, exacerbated by forceful pinch and torsion (unscrewing jar top). Chronic instability means complete tear (partial tears typically heal without laxity)

Front 62

How is a chronic UCL rupture repaired?

Back 62

1. Adductor advancement
2. Reconstruction with palmaris

Front 63

How are partial and complete thumb RCL tears repaired?

Back 63

Partial: cast/splint, very unlikely to have Stener lesion as abductor aponeurosis is broad.
Complete: reapproximation, abductor advancement, free tendon grafting

Front 64

In what direction does the thumb MPJ usually dislocate?

Back 64

Dorsally, via hyperextension and rupture of volar plate, capsule, collaterals

Front 65

What are the three planes of motion of the thumb TMC joint?

Back 65

1. Flexion-extension
2. Abduction-adduction
3. Pronation-supination

Front 66

What are the four major ligaments of the thumb TMC joint?

Back 66

Volar/anterior oblique, intermetacarpal,dorsal-radial, dorsal oblique (posterior oblique)

Front 67

What ligament is the primary stabilizer of the TMCJ?

Back 67

Volar oblique: passes from trapezium to volar beak of thumb metacarpal, provides primary restraint to dorsal subluxation (with pinch)