Pipjw
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PIPJ Anatomy
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
Anatomy
PIPJ - Hinge joint Arc of motion up to 1100
Stability: Articular contours Periarticular ligaments Secondary stabilization by adjacent tendon &
retinacular systems
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)
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
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
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
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
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
PIPJ - Secondary Stabilization
Secondary stabilization by adjacent tendon & retinacular systems
PIPJ dislocations
Dorsal PIPJ Dislocation
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.
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
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
Dorsal PIPJ Dislocations
Treatment depends on open vs closed, stable vs unstable injuries
Rx principles: Patient education Avoidance of prolonged immobilisation
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)
Dorsal PIPJ Dislocations
Complications of operative Mx: Redisplacement Angulation Flexion contracture DIPJ stiffness