Hip luxation Flashcards
What are the primary and secondary stabilizers of the hip joint?
Primary: ligament of the head of the femur, joint capsule, dorsal acetabular rim.
Secondary: Acetabular labrum (transverse ligament ventrally), hydrostatic pressure, periarticular muscles (gluteals, iliopsoas, quadratus femoris, gemelli, internal and external obturator).
How many of the primary stabilizers of the hip need to be disrupted for luxation to occur?
Two (out of 3)
True or false. In immature dogs fractures of the capital physis are less likely to occur than hip luxation?
False
What percentage of hip luxations are craniodorsal?
75%
What injury might occur in conjunction with ventrocaudal luxation of the hip?
Avulsion fracture of the greater trochanter.
What is the function of the gluteal muscles on the hip joint?
Extension of the hip joint, with internal rotation and abduction of the femur
How do patients with craniodorsal hip luxation typically hold the affected pelvic limb?
External rotation and adduction.
Patients with caudoventral luxation typically hold the limb internally rotated and abducted.
What are some clinical findings associated with craniodoral hip luxation?
- Shortening of the limb.
- Adduction and external rotation of the hip.
- Assymetry of the hips.
- Increased distance between the greater trochanter and the ischiatic tuberosity, and failure to ‘push-out’ a thumb placed in the ischiatic notch during external rotation of the femur.
- Crepitus of the hip joint.
- Proximal displacement of the greater trochanter in relation to a line between the craniodorsal iliac spine and the ischiatic tuberosity.
Within what timeframe should coxofemoral luxation ideally be treated?
72 hours
When should immediate open reduction of hip luxation be considered?
Acetabular or femoral head fractures, reluxation after closed reduction, concurrent injuries that require immediate return of hip joint function, chronic luxation requiring assessment of the joint cartilage.
If a hip joint is dysplastic should closed reduction be attempted?
No - ideally FHO or THR are performed.
Reluxation of the hip occurs in what percentage of patients following closed reduction?
50%.
Most likely to occur with external rotation of the hip or hip extension for craniodorsal luxations. Dysplastic and chronically luxated hips also at increased risk of re-luxation.
What is the function of the Ehmer sling?
Internal rotation and abduction of the femur, flexion of the hip joint. Should be kept in place for 10-14 days.
What is the reported rate of reluxation rate following Ehmer sling application alone after closed reduction?
15 - 71%
What is the function of hobbles?
To prevent limb abduction following closed hip reduction for ventrocaudal luxation.
What is the success rate of closed reduction of ventral hip luxations without the use of hobbles?
80%
Aside from use of an Ehmer sling and hobbles, what other augmentation techniques are available following closed hip reduction?
Ischioilial pinning, ESF, transarticular pinning
What is the complication rate of ischioilial pinning for maintenance of closed hip reduction?
32% (contact with sciatic nerve in 75% of cases when the pin is inserted in the center of the ischium). These include; pin migration, reluxation, sciatic nerve injury, damage to the femoral head, joint sepsis.
What is the success rate of ischioilial pinning in preventing hip reluxation?
73%
What is the success rate following open surgical reduction of hip luxation?
85%
What approach to the hip joint is used for dorsal and ventral luxations?
Dorsal: craniolateral.
Ventral: dorsal.
Name 8 surgical techniques that may be used for open reduction of hip luxation.
- Capsulorrhaphy
- Prosthetic joint capsule
- Transposition of the greater trochanter
- Transarticular pinning
- Toggle rod
- Fascia lata loop stabilization,
- Transposition of the sacrotuberous ligament
- Extra-articular iliofemoral suture.
What is the reported success rate of capsulorrhaphy for open hip reduction?
83 - 90%, however may not be possible if the joint capsule is severely damaged
What technique may be combined with capsulorrhaphy to potentially help maintain hip reduction?
Deep gluteal tenodesis.
How is the prosthetic capsule technique performed?
Screws and washers or bone anchors are placed in the acetabulum and suture is passed in a figure of eight pattern around the screws and through a hole in the femoral neck.
In what percentage of cases is the prosthetic capsule technique reported to prevent hip reluxation?
66 - 100%
What are some complications associated with the prosthetic capsule technique for open hip reduction?
Damage to the articular cartilage, reluxation through the web of suture material, displacement of the suture from the screw heads, infection.
In what percentage of cases is transposition of the greater trochanter reported to prevent hip reluxation?
84%
What are the two methods of transarticular pinning?
Normograde or retrograde (if performed open).
The pin is left in place for 2-3 weeks.
What is the reported success rate of transarticular pinning for open hip reduction?
80% at maintaining joint reduction. However results are worse in heavier dogs or patients with pre-existing hip dysplasia (unsatisfactory outcomes in 40% of patients weighing >20%)
What are some complications of transarticular pinning for open hip reduction?
Cartilage damage, sciatic nerve injury, pin migration, perforation of the rectum, pin bending or breakage, OA.
Why is closed application of a toggle rod with the use of fluoroscopy no longer recommended?
It resulted in cartilage damage in 20% of cases.
What is one of the main advantages of use of toggle rod for maintaining hip reduction?
Allows early use of the limb post-operative, which may be required in patients with additional orthopedic injuries.
Why is closed application of toggle rod using fluoroscopy not currently recommended?
Resulted in cartilage damage in 20% of cases.
What are some materials that have been used in toggle-rod stabilization of hip luxation?
Woven polyester, monofilament nylon, and FiberWire.
The Tightrope system has also been used for Toggle rod.
What techniques can be combined with toggle rod stabilization of the hip?
Capsulorrhaphy, prosthetic capsule technique, transposition of the greater trochanter.
What is the reported rate of reluxation following toggle rod fixation?
6% (81% of dogs had little or no long term lameness)
What are some complications reported with the use of toggle rod repair for hip luxation?
Premature suture failure; joint reluxation; injury to the rectum; sciatic nerve damage; articular cartilage damage; and transient lameness.
What is fascia lata loop stabilization for repair of hip reduction?
Similar to toggle rod fixation except that fascia lata rather than suture material is used.
What is transposition of the sacrotuberous ligament for repair of hip reduction?
Similar to the toggle rod except the sacrotuberous ligament is used. It is detached from its attachment on the ischium, including a piece of bone. It is then passed from medial to lateral through the acetabular and femoral head bone tunnels, and attached to the femur using a bone screw.
Where is the suture passed in for extra-articular iliofemoral suturing of the hip, to prevent coxofemoral luxation?
From the ilium just cranial to the acetabulum, through a hole drilled caudal to cranial through the femur just distal to the insertions of the gluteal muscles.
What are reported surgical options for ventral hip luxation?
Prosthetic capsule or toggle rod +/- (if necessary) ventral augmentation. This may include:
1) Suturing of ventral acetabular ligament
2) Autogenous iliac crest shelf graft.
3) Extracapsular sling
4) internal fixator plate to augment the ventral acetabular rim.
Trochanteric transposition is not recommended.
Is progression of osteoarthritis common after closed or open hip reduction?
Yes - progresses in 55-62% of dogs and is more severe in heavier patients.
Asides from closed or open coxofemoral reduction techniques, what other surgeries might be indicated in the treatment of coxofemoral luxation?
- FHO
- TPO
- THR
According to Mathews 2020 in Vet Surg, what were two risk factors for hip reluxation following toggle rod stabilization? What was the overall rate of reluxation?
Decreased risk when the luxation was traumatic in nature, and the lameness was severe at presentation.
Overall rate of reluxation was 15%.
In a study by Ruperez 2021 in Vet Surg what was the most common post-operative complication following toggle rod repair of feline hip luxation? What 3 factors were associated with an increased risk of this complication?
Reluxation was the most common complication (11.1% of cases).
Performance of additional orthopedic procedures, occurrence of intraoperative complications, and non-performance of capsulorrhaphy were associated with reluxation.
In a study by Ruperez 2023 in Vet Surg, what were three issues identified with arthroscopic assisted hip toggle stabilization?
Intraoperative complications related to bone tunnel formation and toggle dislodgement, cartilage injury, and deviations in planned surgical technique.
In a study by Loh 2024 in Vet Surg, what was the success rate of ventral hip luxation treated by closed reduction alone, closed reduction and Ehmer sling, and closed reduction and Hobbles? What 3 factors were associated with successful non-surgical treatment?
9%, 15%, 49%.
Factors associated with successful treatment were increasing age, treatment by a specialist, and use of Hobbles.
Additional info: most ventral hip luxations were caused by low impact trauma (83%). Success rate for toggle rod was 88%. Complication rate of hobbles was 32% (half that of Ehmer slings).
In a study by Schalg 2019 in JAVMA, what was the rate of hip reluxation following Ehmer sling placement? What percentage of dogs had soft tissue injuries related to sling use? What were 3 factors associated with an increased risk of complication?
Reluxation rate was 43% (5x as likely for those patients suffering traumatic hip luxations).
50% of dogs had soft tissue injuries associated with sling use.
Three factors associated with increased risk of complications included poor owner compliance (13 x as likely), intern placing the bandage (4 x), wet or soiled (6x).
In a study by Knell 2023 in VCOT, was use of a double or single strand mini-Tightrope system associated with a decreased risk of suture failure when used for toggle pin of feline coxofemoral luxation?
Double strand (1/12 cats) compared to single strand (4/16) cats had suture failure. Reluxation was the most common post-operative complication.
Osteoarthritis was common post-operative, but outcomes were generally considered excellent.
In a study by LeFloch 2022 in JFMS, what was the success rate for cats undergoing closed hip reduction? What reduced the risk of reluxation?
51%
Application of a bandage (either Ehmer sling or hobbles) reduced the risk of reluxation.
