The sacroiliac joints join the pelvis to the spine
A blow to the hind end can result in dislocation of one or both sacroiliac joint
This can result in severe lameness or nonweight-bearing lameness of the hind limb(s)
Sciatic nerve damage can occur in cases that sustain a sacroiliac joint dislocation
Other concurrent injuries that must be ruled out include rupture of the bladder, rupture of the lung, and internal hemorrhage from trauma to the spleen or liver
- The pelvis consists of two symmetrical sets of bones that are fused together to form a solid bone. The pelvis is attached to the lower part of the spine, called the sacrum, by a a left and right sacroiliac joints. Unlike the hip, knee, elbow and other joints, the sacroiliac joints have limited movement.
- The sacrum consists of three spinal bones that are fused together
- Anatomy key:
- large arrow = sacroiliac joint
- S = sacrum (fused lower spine bones)
- I = ilium (shaft of the pelvis)
- A = acetabulum (hip socket)
- Is = ischium
- The sciatic nerve runs immediately below the sacroiliac joint, thus this nerve is susceptible to damage
- Sacroiliac luxation (luxation = dislocation in layman’s terms) usually is caused by a very traumatic blow to the hind end of an animal (i.e. hit by a motor vehicle).
- Varying degrees of lameness on the side of the luxation.
- Pain is noted when the sacroiliac joint is palpated.
- The pelvis may feel crunchy (crepitant) when a force is applied to the front of the pelvis.
- If the sciatic nerve was also injured, no or decreased sensation to the outside toe of the affected hindlimb will be noted; complete evaluation of the sciatic nerve may be difficult due to bruising of muscles and the nerve itself.
- Prior to surgery the following tests are usually performed:
- Bloodwork such as CBC and chemistry profile
- Radiographs (x-rays) of the chest to rule out trauma to the lungs or ribs
- Radiographs or ultrasound of the abdomen to rule out internal organ damage and internal bleeding
- Radiographs of the pelvis; the unfractured pelvis should fit within an imaginary box and if it does not, there is a fracture +/- dislocation the sacroiliac joint (put your cursor on radiograph below left) a part of the pelvis will be shifted outside this box. In this case, take note of the sacroiliac luxation and fractures of the pubis and ischium of the pelvis.
- There are three options for treatment of a sacroiliac luxation
- Conservative treatment is acceptable if only one side of the pelvis has been damaged, and minimal displacement of the sacroiliac joint is present. These patients will be painful for a much greater time versus having the luxation surgically repaired.
- Traditional surgery involves making a sizeable incision along the side of the pelvis and peeling the muscles off the bones to expose the dislocated joint (photo right). Screws are used to secure the dislocated joint in place.
- Minimally invasive surgery involves manually reducing the joint back into place from the outside, making a small incision (about 1 to 1.5 cm) over the side of the pelvis in the location of the sacroiliac joint and securing the sacroiliac joint in place with screws with the aide of fluoroscopy or digital radiography.
- The details: The patient is placed on the x-ray table with the affected pelvis up. Digital radiographs are made (or fluoroscopy used) to assist the surgeon in the placement of the screws. The ilium is manually pushed back into place and a small pin is inserted. Next, a hole is drilled over sacral body and the position of the drill bit is radiographed. If the positioning is good, the drill bit is advanced deeply into the sacrum. The drill bit is removed and a screw (premeasured screw length from the radiographs) is seated into the bones to hold the sacroiliac joint in place. Another screw is placed just behind the first screw using the same method.
- The benefits of this minimally invasive approach is that a very small incision is used and there is minimal dissection of the soft tissues, resulting in less pain. In addition, the surgeon can very accurately place the screws into the body of the sacrum, thereby preventing damage to the nerves that are located in the spinal canal of the sacrum. The length of time that it takes to perform the minimally invasive versus traditional surgery is similar.
- The radiographs below were taken during surgery. Place your cursor over images to see additional images.
- Limit activity until the fractures have healed
- Provide a soft bed to prevent bed sores
- Turn your pet from side to side, if your pet is very weak and cannot do this
- Check the incision for infection
- Use a towel as a sling to take your pet outside for elimination purposes
- Sciatic nerve damage
- Nonhealing of the fractures
- Breakage of the screws
- Anesthetic death
- Pregnancy should be avoided as natural delivery of the puppies may not be possible due to scar tissue or callus formation in the pelvic canal (C-section is also an option if breeding is a must)
- Chronic constipation if a lot of callus or scar tissue develops in the pelvic canal
- Entrapment of the urethra (tube from the bladder for urination) by fracture fragments
- Most patients heal well following surgical repair. It may take about 2 months for full recovery.
- Patients that have sciatic nerve injury frequently will regain normal or near normal function; occasionally the function of the nerve does not come back and the pet does not have any useful function of the limb.