Hip/Pelvis Flashcards
List four dangers of the Stoppa approach
Corona Mortis (lateral 1/3 sup. pubic ramus)
Bladder (insert foley)
Obturator nerve and vessels (when exposing quad plate)
External iliac vessels (mobilize early)
What is the potential space of retzius ?
Anterior to bladder post to pubic symphysis
What muscle do you have to take down to see quadrilateral plate?
Obturator internus
What fascia separates the middle and lateral window of the ilioinguinal approach?
Iliopectineal fascia
List five contents of the Greater sciatic notch
Exit above piriformis
- Superior gluteal artery and nerve
Exit below piriformis
POPSIQ
- Posterior femoral cutaneous nerve
- Nerve to Obturator internus
- Pudendal nerve and internal pudendal artery
- Sciatic nerve
- Inferior gluteal nerve and artery
- Nerve to quadratus femoris
piriformis
superior and inferior gluteal vessels and nerves
sciatic and posterior femoral cutaneous nerves
internal pudendal vessels
nerves to the obturator internus and quadratus femoris
List the structures that separate the windows in the ilioinguinal approach
Lateral: Iliac wing to Iliopsoas and femoral nerve
Middle: psoas to External iliac vessels
Medial: External iliac vessels to rectus abdominus
What are the Denis zones of the sacrum?
1: lateral to foramen
2: middle
3: medial to foramina into spinal canal
What nerve root runs along the sacral ala?
L5
What is the sacral ala?
The lateral aspect of the sacrum; lateral to the body, forming articulations with the iliac wing
What is the importance of iliac cortical density?
On the lateral is the overlying projection of the alar slopes, you want to be behind this when inserting an SI screw in order to avoid the L5 nerve root
On an AP pelvis is the posterior wall lateral or anterior?
Lateral!
Describe what you look for on Judet views.
Obturator oblique - AC (iliopectineal line), PW
Iliac oblique - AW, PC (ilioischial line)
What is a Morel-Lavallée lesion?
Internal degloving of subcutaneous tissue off of the underlying fascia.
Traditionally this term is reserved for lesions overlying the GT however this mechanism and injury has been seen all over the body and Morel-Lavallee is the term generally used.
What are key SI ligaments?
What are the other three important pelvic ligaments?
The posterior SI ligament complex are the strongest ligaments in the body
- Anterior Sacroiliac ligament - resist external rotation after failure of pelvic floor and anterior structures
- Posterior Sacroiliac ligament - resist cephalad-caudad displacement of pelvis
- Interosseous Sacroiliac ligament -
resist rotation and augment posterior SI ligaments
Also:
- Sacrotuberous - Sacrum to Ischial tuberosity. The sacrotuberous ligament passes behind the sacrospinous ligament. Is the inferior boundary of the lesser sciatic notch
- Sacrospinous - Sacrum to Ischial spine - Converts the sciatic notch into the greater and lesser sciatic foramen. The greater sciatic foramen lies above the ligament, and the lesser sciatic foramen lies below it.
- Iliolumbar ligament- •Iliac crest to transverse processes of 5th Lumbar. It forms the thickened lower border of two of the layers of the thoracolumbar fascia. Fracture of the fifth lumbar vertebra is a clue to an unstable pelvic fracture (JBJS 2011, see below)
An associated fracture of the transverse process of L5 was present in 17 patients; 14 (40%) of whom had an unstable fracture pattern. Overall, 14 of the 35 unstable injuries (40%) had a fracture of the transverse process, compared to only three of the 45 stable fractures (7%). The odds ratio for an unstable fracture of the pelvis in the presence of a fracture of the transverse process of L5 was 9.3 and the relative risk was 2.5. A fracture of the transverse process of L5 in the presence of a pelvic fracture is associated with an increased risk of instability of the pelvic fracture.
FURTHERMORE:
It is well documented that there is a strong association between transverse process fractures and abdominal injury. One study reports an association of up to 50%.9 In our study this was 12% (2 of 17).
Name the Contents of the Sciatic Notch Relative to Piriformis
Contents of GSN:
Above piriformis:
- Superior Gluteal Nerve & Artery
Below Piriformis (POPS IQ):
- Pudendal nerve and internal pudendal artery
- Nerve to Obturator internus
- Posterior femoral cutaneous nerve
- Sciatic nerve
- Inferior gluteal artery and nerve
- Nerve to Quadratus femoris
What travels through Lesser Sciatic Notch?
- Obturator internus muscle
- Nerve to obturator internus
- Pudendal nerve
- Internal pudendal artery and vein
Name the nerves relative to psoas:
- Lateral (3)
- Medial (2)
- Between iliac and psoas (1)
- Piercing them (1)
Lateral - iliohypogastric, lioinguinal, LFCN
Medial - obturator, lumbosacral trunk
Between - femoral
Piercing - genitofemoral
What is the cruciate anastomosis made of?
What vessels is the trochanteric anastamosos comprised of?
Cruciate anastamosis (looks like a cross)
First perforator of profunda
Inferior gluteal artery
Transverse branches of MCFA
Transverse branches of LCFA
this is an anastomosis between basically the internal iliac (via gluteal aa) and the Profunda femoris via the lateral circumflex artery.
If either femoral aa (SFA or Profunda) becomes occluded, collateral flow to the popliteal artery can be established via the cruciate anastamosis in the following way:
Internal iliac –> to Inferior Gluteal artery –> to perforator of the Profunda femoris –> to the DESCENDING branch of the lateral circumflex artery to the superior lateral geniculate aa to the popliteal artery.
IT IS NOT ENTIRELY CLEAR WHERE THIS IS REFERENCED FROM.
Trochaneteric Anastamosis
The trochanteric anastomosis is formed by the following arteries:
- Ascending branch of the medial circumflex femoralartery.
- Ascending branch of lateral circumflex femoral artery.
- Descending branch of the inferior gluteal artery .
- Descending branch of the superior gluteal artery.
What nerve is at risk with a retractor under transverse acetabular ligament?
If you bagged this nerve what muscles would be affected?
Obturator Nerve - posterior division
If you bagged this nerve what muscles would be affected?
- Obturator externus
- Adductor magnus
- Adductor brevis
How can we adduct after an obturator neurectomy
Pectineus, femoral
What nerve is above piriformis?
Superior gluteal nerve
What structure is most at risk of posterior ICBG harvest?
Superior gluteal artery and nerve (penetration into the notch)
cluneal nerves (use a vertical incision to avoid this)
Between What muscles does the posterior obturator nerve run between?
Adductor brevis and magnus
In the anterior Smith-Peterson approach the deep interval is between?
Rectus femoris (femoral)
and
Gluteus medius (superior gluteal)
What type of joint is the pubic symphysis?
Name the ligaments connecting the pubic sympysis.
non-synovial amphiarthroidal joint
Superior pubic ligament (stronger)
Inferior (arcuate) public ligament
What type of joint is the pubic symphysis?
non-synovial amphiarthroidal joint
What do the medial sacral crest and alae of the sacrum represent embryologically?
Medial sacral crest: fused spinous processes
Alae and SI articular processes: fused TP and costal processes
What strucures are near the posterior sacral foramina?
Dorsal primary rami
List the signs of sacral dysmorphism
5 signs:
Sacralization of L5
Lumbarization of S1
Mammillary processes
Oval or oblong foramen
Tongue in Groove sign of SI joint
What structures are near the anterior sacral foramina?
Ventral primary rami
In which direction are the coccyx of men and women directed?
Men: anteriorly towards pubis (like a penis)
Women: vertically
Where does the sacrotuberous ligament, sacrospinous ligament and iliolumbar ligaments run?
Sacrotuberous: sacrum to ischial tuberosity
Sacrospinous: sacrum to ischial spine
Iliolumbar: iliac crest fo 5th lumbar TP
What are the superficial surface markings of the SI joint?
Dimples of Venus
also said to be a marker of the PSIS
What are the borders of the lesser sciatic foramen?
Ischial spine and tuberosity
sacrospinous ligament (superior border)
sacrotuberous ligament (inferior border)
What is the obturator foramen, membrane and canal?
Foramen: big hole between pubic rami
Membrane: Membrane that covers the foramen (obturator int/ext attach)
Canal: superior opening in membrane, allowing passage of obturator n/a/v
At what age are the SI joints fused by?
Age 50
Name the ligaments of the SI joint
Posterior
Anterior
Interosseous
What are the boundaries of the greater sciatic notch?
It is bounded as follows:
- anterolaterally by the greater sciatic notch of the ilium
- posteromedially by the sacrotuberous ligament
- inferiorly by the sacrospinous ligament and the ischial spine
- superiorly by the anterior sacroilliac ligament
What attaches to the obturator membrane?
Obturator internus
and externus
Describe the criteria for an adequate AP pelvis x-ray
- Coccyx in line with symphysis
- Symmetric teardrops
- Symmetric Obturator foramina
- Symmetric iliac wings
- Superior border of pubic symphsis to coccyx should be 1-3 cm
- Superior border of pubic symphsis to sacrococcygeal junction distance of:
- 32mm in men
- 47mm in women
(However, visualization of the sacrococcygeal junc- tion can often be difficult, making the tip of the coccyx a more reliable landmark)
Clohisy, Beaule et al - A Systematic Approach to the Plain Radiographic Evaluation of the Young Adult Hip. JBJS 2008
As seen in Figure 8, the coccyx should be directly in line with the pubic symphysis, and the iliac wings, obturator foramina, and radiographic teardrops should be symmetrical in appearance. Additionally, if pelvic inclination is appropriate, the distance between the superior border of the pubic symphysis and the tip of the coccyx should be approximately 1 to 3 cm. Siebenrock et al.28, who published sex-specific values for pelvic tilt (referencing the distance between the superior aspect of the symphysis and the sacrococcygeal junction), noted that an average distance of 32.3 mm was typical in men, as compared with 47.3 mm in women. However, visualization of the sacrococcygeal junc- tion can often be difficult, making the tip of the coccyx a more reliable landmark.
List the 6 fundamental lines of Letournel
- Posterior wall
- Anterior wall
- Roof (or dome/tectum)
- Teardrop
- ilioischial line (posterior column)
- iliopectineal line (anterior column)
What are the ligaments that make up the hip capusle?
Anterior:
Iliofemoral ligament (Y ligament of Bigelow): Strongest ligament that runs from AIIS to intertrochanteric line
Pubofemoral ligament
Posterior:
Ischiofemoral ligament: attaches to femoral neck
What angle is classically measured off a Dunn view?
How do you take a Dunn View?
Alpha angle
It is calculated by measuring the angle between two lines: (1) a line from the center of the femoral head to the point on the ante- rolateral aspect of the head-neck junction where the radius of the femoral head first becomes greater than the radius of the femoral head found more centrally in the acetabulum (i.e., where a prominence starts),
and
(2) a line drawn through the center of the femoral neck, connecting to the center of the femoral head. Values of >42° are suggestive of a head-neck off- set deformity.
( The upper end of normal is an alpha angle of 50 - 55 degrees for measurement on an MRI or CT. i.e >55 is cam, some au)
Dunn View
The positioning for a 45° Dunn view with the hips flexed 45° and abducted 20°. The x-ray beam is centered at a point midway between the pubic symphysis and the anterior superior iliac spine
Describe the proximal femur blood supply
MFCA: femoral head via retinacular vessels
LFCA: GT
Obturator: vessels within ligamentum teres
What are the borders of the femoral triangle?
What makes up the floor, in what order?
Sartorius: laterally
Adductor longus: medially
inguinal ligament: superiorly
Floor (lat to med): iliacus, psoas, pectineus, adductor longus
Roof: Fascia lata except at the saphenous opening where it is bounded by the cribriform fascia (aka Hesselbach’s fascia) is the portion of fascia covering the saphenous opening in the thigh. It is perforated by the great saphenous vein and by numerous blood and lymphatic vessels
What angle is measured from a false profile view?
Anterior CEA
Describe the safe zone for acetabular screws:
Which zone is safe? Dangerous? What is at risk in each zone?
Divided into quadrants with one line running from ASIS to center of acetabulum and another line perpendicular to that
- Posterior superior (Target zone): sciatic nerve, superior gluteal n/a/v
-
Posterior inferior (Caution Zone)
-
safe if screws <20mm
- Dangers
- sciatic nerve
- inferior gluteal aa and nn
- Pudendal nerve and internal pudendal artery
- Dangers
-
safe if screws <20mm
-
Anterior inferior (Danger zone):
- obturator n/a/v (b/c aiming for obturator foramen)
- In particular the posterior branch of obturator nerve is at risk
- obturator n/a/v (b/c aiming for obturator foramen)
-
Anterior superior (Death zone)
- Dangers
- external iliac artery/veins
- Dangers
Name the short external rotators, from most proximal to most distal (6):
Piriformis
Gemellus superior
Obturator internus
Gemellus inferior
Obturator externus
Quadratus femoris
Name the OINA of all the muscles of the hip - see list in answers
Good luck
Where is the sciatic nerve most likely to be found in relation to piriformis and SERs?
Deep to piriformis, superficial to SER
- Usually sits on top of SER, that’s why during a posterior approach you can use them to protect it
A patient is undergoing percutaneous S1 SI screw fixation for a sacroiliac joint diastasis. What is the most common strength deficit sequela of this proposed screw trajectory?
- Loss of hip flexion
- Loss of knee extension
- Loss of ankle dorsiflexion
- Loss of great toe extension
- Loss of ankle plantar flexion
4: Loss of great toe extension due to damage to L5
What is the origin of LFCN and where does it exit pelvis?
L2-3
Exits pelvis under inguinal ligament, 2cm distal to ASIS
What is the most common position of the sciatic nerve in relation to the piriformis? What are the other variants?
See picture
What are the branches of the femoral artery (6)?
The superficial circumflex iliac artery is a small branch that runs up to the region of the anterior superior iliac spine.
The superficial epigastric artery is a small branch that crosses the inguinal ligament and runs to the region of the umbilicus.
The superficial external pudendal artery is a small branch that runs medially to supply the skin of the scrotum (or labium majus).
The deep external pudendal artery runs medially and supplies the skin of the scrotum (or labium majus).
The profunda femoris artery is a large and important branch that arises from the lateral side of the femoral artery about 1.5 in. (4 cm) below the inguinal ligament. It passes medially behind the femoral vessels and enters the medial fascial compartment of the thigh. It ends by becoming the fourth perforating artery. At its origin, it gives off the medial and lateral femoral circumflex arteries, and during its course it gives off three perforating arteries.
The descending genicular artery is a small branch that arises from the femoral artery near its termination within the adductor canal. It assists in supplying the knee joint.
What is the interval in the approach to the SI Joint?
Between Gluteus Maximus (inferior gluteal nerve)
and
Multifidus (mulitple posterior spinal nn branches)
What are the 3 variations of the LFCN?
Sartorius type (36%)
Posterior Type (32%)
Fan Type (32%)
What are two approaches you can use to access the hip anteriorly, what are their intervals?
- hueter aka Smith Peterson - TFL and sartorius, rectus, glut medius
- watson jones - TFL and GM. need to osteotomize GT or release the abductors to dislocate hip and access socket
What are 5 blocks to reduction in a congential dislocated hip DDH?
- pulvinar
- limbus
- transverse acetabular ligament
- capsule (constricted, hourglass)
- ligamentum teres
- labrum
