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Luxation
Luxation = displacement of articular surfaces from the normal position within a joint. Subluxation = Partial dislocation from the normal position within a joint.
True or False luxations and subluxations can be congenital or acquired
True.
How can Luxation and Subluxation be repaired?
Repaired via open or closed reduction
What is closed reduction - how is it performed?
Closed reduction is done by manipulating the joint into correct anatomical alignment. This should be carried out under general anaesthesia due to pain felt under sedation. X-rays should be taken afterwards to ensure the reduction was successful
What is open reduction
Open reduction is the surgical approach where the luxated bones are visualised and manipulated back into the joint.
Closed reduction patients should have what applied? and for how long?
A VALPEAU or EHMER should be applied and kept on for 5-7 days
How long should exercise be restricted for, for a luxation?
3-4 weeks
What is an Ehmer sling?
Ehmer sling is used to support the hind limb following reduction of hip luxation.
What is a Valpeau sling?
This is used to support the shoulder joint following luxation, bursitis, and non-displacement fracture of the scapula or humerus.
What is the most common luxation
Patella luxation
What is a patella luxation
A luxating patella is a condition in which the patella dislocates and moves out of the trochlear grove causing pain and discomfort to the patient.
What is a luxating patella commonly found in?
Small cats and dogs - basset hounds are prone due to the abnormal shape of the femour and tibia - The curves of the bones work with the forces of the quadriceps muscles to displace the patella.
Where is the patella found? and how does it work?
The patella is found on the cranial surface of the stifle; it sits in the trochlear groove and is held in place by tendons and ligaments. It moves every time the knee bends or straightens
What part of the body is affected by a luxating patella?
Hind legs - can affect one or both
Clinical Signs
- Intermittent lameness
- Pain
- Affected limb may temporarily lock into place
- Skipping gait
What causes a luxating patella
Congenital abnormality in the formation of the patellar groove. The trochlear groove fails to develop normally, and is too shallow. This can be apparent as early as four months old. The other cause is due to trauma.
Name the 4 grades involved with luxating patellas
Grade 1: The patella is positioned normally but can be luxated with slight manual pressure
Grade 2: Spontaneous luxation occurs, however it can reduce spontaneously or can be replaced manually
Grade 3: The patella is luxated most of the time, however it can be replace manually
Grade 4: The patella cannot be reduced manually
Diagnosis of the patella involves?
Examined by the vet
Sedated xrays to evaluate alignment
Arthrocentesis - aspirate synovial fluid for analysis of infections
How can a luxating patella be managed?
Medical treatment or surgery for patellas graded 2-4
What surgerys are there for luxating patellas?
Abrasion Trochleoplasty
Trochlear Wedge Sulcoplasty/ Recession
Trochlear Block Sulcoplasty/ Recession
Tibial Tuberosity Transposition
What is Abrasion Trochleoplasty? + instruments needed
This involves the removal of the articular cartilage and subchondral bone from the trochlea sulcus. It is less technically demanding than other surgical repair options. Instrumentation required: Gelpies, Rongeurs/or Bone Rasp.
What is Trochlear Wedge Sulcoplasty/ Recession? + instruments needed
This involves the removal of a ‘V shaped’ wedge of bone and cartilage from the femoral trochlear sulcus, followed by replacement of the original wedge in a recessed position. This surgical approach is more technically demanding. Instrumentation required: Fine toothed hand saw blade, Rongeurs and the Gelpies.
What is Trochlear Block Sulcoplasty/ Recession? + instruments needed
This involves the removal of a block from the femoral trochlea sulcus. This surgical approach provides a bigger proximal recession, which may provide more stability for the patient. It is a technically demanding surgery. Instrumentation required: Fine tooth hand-saw blade, modular osteotome, Mallet, Rongeurs, and the Gelpies.
What is Tibial Tuberosity Transposition? + Instruments needed
This surgical approach is used to improve alignment of the patellar mechanisms for patients who have an abaxially displaced tibial tuberosity. This involves cutting the tibial tuberosity and transpositioning laterally to achieve neutral orientation of the patella ligament. Instrumentation required: gelpies, mallet, rongeurs, Bone Rasp, IM Pins (K wire), Jacobs chuck handle and key, sagittal saw, listen bone cutters, modular osteotome, cerclage wire, wire twisters (possibly lag screw).
How is the clipping performed?
- dorsal or lateral recumbency
- Place non sterile glove over foot of the limb needing surgery
- Wrap in a non sterile bandage or micropore tape and hang this to an iv pole so the limb is elevated prior to the surgical prep.
Where do you clip?
Best practice to clip the fur from the hip to the tarsus circumferentially, this is so that the surgeon can move and manipulate the leg without contaminating the surgical field
Prep
Linear scrub is preferred
Surgical positioning
dorsal recumbency however some vets request lateral recumbency with the affected limb uppermost
Instruments
Four quarter drape General surgical kit Rongeurs Gelpies Fine tooth hand saw
