3. Proximal Interphalangial Joint
Anatomical & functional locus of finger function
Site of most common ligament injury in the hand
Most ligament injury are incomplete with
maintenance of joint congruity & stability
In certain injuries (eg. Lateral dislocations &
hyperextension injuries) --> complete rupture of one
or more supporting structures
Treatment based on accurate diagnosis of
pathological lesions & degree of clinical dysfunction
4. Anatomy
PIPJ - Hinge joint
Arc of motion up to 1100
Stability:
Articular contours
Periarticular ligaments
Secondary stabilization by adjacent tendon &
retinacular systems
5. Anatomy - Bony Factors
Head of PP - 2x concentric condyles seperated by an
intercondylar notch
Condyles (PP) articulate with 2x concave fossa in the
broad, flattened base of MP separated by a median
ridge
Tongue-and-groove contour & breadth of
congruence add stability by resisting lateral &
rotatory stress (esp. when PIPJ is fully extended)
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7. Anatomy - Ligamentous factors
Radial & ulnar collateral ligaments
Primary restraints to radial & ulnar deviation force
Proper & accessory component
Both arise from the concave fossae on lateral aspects
of each condyle & pass obliquely & volary to their
insertions
Anatomically confluent but distinguished by their
points of insertion
Proper collateral lig. --> volar 1/3 base of MP
Accessory collateral lig. --> volar plate
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10. Anatomy - Volar Plate
Floor of joint
Suspended laterally by collateral
ligs.
Distal portion inserts across volar
base of MP (only densely
attached at its lateral margins -
col. lig. insertion)
Thinner centrally & blends with
MP volar periosteum
Central portion tapers proximally
into an areolar sheet & laterally
thickens to form a pair of check
ligaments
Secondary stabilizer against
lateral deviation esp when PIPJ
extended but only when
collaterals torn
11. Check ligaments:
+Originate from periosteum of PP1 just inside walls of
A2 pulley at its distal margin and are confluent with
proximal origins of C1 pulley
+prevent hyperextension while permitting full flexion
thereby providing maximum stability with minimum
bulk
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13. PIPJ Stability
Key: strong conjoined
attachment of the paired
collateral lig. & the volar plate
into the volar 1/3 of the MP
Ligament-box configuration
produces a 3D strength that
strongly resists PIPJ
displacement
For MP displacement to occur,
the ligament-box complex must
be disrupted in at least 2
planes
14. PIPJ Stability
Based on load to failure cadeveric studies & clinical observation,
collateral ligs. fail proximally about 85% of the time while the volar
plate avulses distally up to 80% of the time
At lower angular velocities of side-to-side deformation, the collateral
ligs. tend to fail in their midsubstance
15. PIPJ - Secondary Stabilization
Secondary
stabilization by
adjacent tendon &
retinacular systems
18. Dorsal PIPJ Dislocations
Mechanism: PIPJ hyperextension combined with
some degree of longitudinal compression
Frequently occurs in ball-handling sports
Usually produces soft tissue or bone injury to the
distal insertions of the 3D ligament-box complex.
The greater the longitudinal force, the more
likelihood for fracture dislocation
Rarely, VP ruptures volarly & become interposed
within the PIPJ causing irreducible dislocation
Volar fracture may even become trapped within the
flexor sheath and inhibit motion.
19. Dorsal PIPJ Dislocations
Type I (hyperextension): VP
avulsed; incomplete
longitudinal split in col. ligs.;
articular surfaces remain
congruous.
Type II (dorsal dislocation):
complete rupture VP; complete
split in col. ligs.; MP resting on
dorsum of PP.
Type III (fracture-dislocation):
disruption at the volar base of
MP where VP is inserted; stable
vs unstable injuries
20. Dorsal PIPJ Dislocations
Stable Type III:
fracture < 40% of volar
base MP; significant
portion of col. ligs. still
attached; possible
congruous reduction
Unstable Type III:
fracture > 40% of volar
base MP; little or no col.
ligs. attached; congruous
reduction unlikely;
depressed volar articular
defect
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37. Dorsal PIPJ Dislocations
Treatment depends on open vs closed, stable
vs unstable injuries
Rx principles:
Patient education
Avoidance of prolonged immobilisation
38. Dorsal PIPJ Dislocations
Operative Mx:
Debridement & joint washout for open injuries
Dorsal block splinting
? Role of primary VP repair
Other specific techniques for unstable PIPJ injuries:
Dynamic skeletal traction
Extension block pinning
Trans-articular pinning
ORIF
Volar plate arthroplasty
FDS tenodesis (for chronic hyperextension deformity of PIPJ)