Hip dislocations can occur posteriorly or anteriorly;
however, any type of hip dislocation is considered an emergency.
Posterior hip dislocations are more common and the lower
limb will be flexed, adducted, and internally rotated. Posterior dislocations
are frequently caused by dashboard injuries. The impact with the car dashboard
drives the femoral head backwards out of the acetabulum. The physician will
want to observe sciatic nerve function and examine the knee to rule out a PCL
injury as well. Weakness of the ankle and toe dorsiflexion due to an injury to
the peroneal division of the sciatic nerve may result in foot drop. The patient
will also be unable to dorsiflex the ankle.
Anterior hip dislocation is rare. Superior Anterior hip
dislocation results from the lower limb being extended, abducted, and
externally rotated. Inferior Anterior Hip Dislocations (obturator type) results
from the lower limb being flexed, abducted, and externally rotated.
An emergency reduction of dislocations is needed in less
than 8 hours of the injury. An urgent reduction is mandatory to avoid avascular
necrosis and interruption of the blood supply, which leads to a collapse of the
femoral head. AVN is the death of a segment of bone.
Treatment
A CT scan should be obtained after reduction to evaluate the
presence of fragments in the joint and access stability of the joint. Hip joint
dislocations may be associated with acetabular or femoral head fractures (Pipkin).
An urgent closed reduction of the hip dislocation followed by stabilization of
either of the fractures if needed according to the protocols.
Proximal interphalangeal (PIP) dorsal fracture dislocations
can be challenging in management. In PIP dorsal fracture dislocations, there
is an involvement of the articular surfaces of the joint. These injuries are the
most disabling PIP joint injuries. A reduction of the middle phalanx on the
condyles of the proximal phalanx is the primary goal of treatment. The patient
frequently presents with a chronic dorsal subluxation due to delay in seeking
treatment or from failed treatment.
85% of motion for grasping objects occurs at the PIP joint.
The PIP joint has the largest arc of motion (120 degrees) of the three joints
in each digit.
There are three different types of injury:
Hyperextension
Impact Shear
Pylon
In cases of Hyperextension injuries, the size of the
fragment can range from a small piece of bone, up to 30% of the joint surface
with minimal comminution (usually stable).In order to provide accurate treatment, the physician will want to test
the stability of the fracture and apply a dorsal blocking splint. It is
important to observe the lateral view for any subluxation.
Impaction/Shear injuries are produced by an axial load
applied to a slightly extended or flexed PIP joint. The middle phalanx is
driven over the head of the proximal phalanx with comminution and impaction of
the base of the middle phalanx. These injuries are characterized by the loss of
the volar plate tether. A 50% loss of the palmar of the middle phalanx base
will make the PIP joint unstable. The extensor tendon and superficialis tendon
will aggravate the dorsal subluxation. Splints will be inadequate if the injury
is not stable. Treatment will include skeletal traction and early range of
motion. An open reduction and internal fixation may be necessary if the
fragment is large enough. A Palmar Plate Arthroplasty may be considered to
advance the palmar plate into the defect. This procedure will support the
palmar plate by filling the defect behind it with fracture chips, bone graft,
or by a superficialis slip. Chronic impaction/shear cases are a difficult
problem and can be treated with an arthrodesis or volar plate arthroplasty.
A pylon fracture results from an axial force that fractures
the volar and dorsal articular surfaces with impaction on the central part. A
pylon fracture is not a true fracture dislocation and will not have a good
outcome. Dynamic external traction should be done in order to help in
ligamentotaxis. Early range of motion is important for remodeling of the joint.
Classification of a PIP Dorsal Fracture Dislocation will
depend on the degree of involvement of the articular surface.
Type I (stable) <30%
Type II (tenuous)= 30-50%
Type III (unstable) > 50%
Treatment will consist of a Dorsal Extension Blocking Splint
if the PIP can be reduced in less than 30% of flexion. If less than 40%, the
joint involved and stable. For Type I and Type II fractures, decrease the
flexion gradually every week. Type III fractures will require ORIF, volar plate
arthroplasty, or hemi-hamate graft (if >40% joint involved and unstable).
With a Hemi-Hamate Graft, the damaged palmar lip of the
middle phalanx with a size matched portion of the hamate bone obtained from its
distal dorsal articular surface between the 4th and 5th
metacarpals. It restores both articular congruity and osseous stability.
Extension block pinning is probably a helpful technique. Treatment must provide
stable reduction to allow for early mobilization.
Stability of the reduction depends on the size of the
avulsed fragment and the amount of ligament remaining attached to the middle
phalanx. If less than 40% of the articular segment is avulsed, some of the
collateral ligament will be intact. This will keep the reduction stable. If
more than 40% of the articular segment has avulsed, only very little or none of
the ligament will remain attached to the base of the middle phalanx, rendering
the reduction unstable.
Recognizing Subluxation
AP and lateral x-rays are necessary for diagnosis. An AP
view will help to recognize impaction fractures.Subluxation can be missed on x-rays. The
physician will want to look for the characteristic “V” sign of diverging joint
surfaces, which indicates injury and subluxation.
If a reduction of the avulsion fracture is achieved with
less than a 30 degree bend, nonoperative treatment is a good choice. However,
if it takes more than 30 degrees of flexion to reduce the fragment, this may be
an indication for surgery.
