Hip

Question 1

Hip dislocations should be reduced within what time frame and why

Answer 1

within 6 h to decrease risk of AVN of the femoral head

Question 2

Hip precautions following dislocation

Answer 2

no extreme hip flexion, adduction, internal or external rotation for 6 weeks post-reduction

Question 3

Concurrence of hip dislocations and fractures

Answer 3

up to 50% of patients with hip dislocations suffer fractures elsewhere at the time of injury

Question 4

Anterior hip dislocation mechanism

Answer 4

posteriorly directed blow to knee with hip widely abducted

Question 5

Anterior hip dislocation clinical features

Answer 5

shortened, abducted, externally rotated limb

Question 6

Anterior hip dislocation treatment

Answer 6

■ closed reduction under conscious sedation/GA

■ post- reduction CT to assess joint congruity

Question 7

Posterior hip dislocation mechanism

Answer 7

severe force to knee with hip flexed and adducted

■ e.g. knee into dashboard in MVC

Question 8

Posterior hip dislocation clinical features

Answer 8

shortened, adducted, internally rotated limb

Question 9

Posterior hip dislocation treatment

Answer 9

■ closed reduction under conscious sedation/GA only if no associated femoral neck fracture or ipsilateral displacement

■ ORIF if unstable, intra-articular fragments, or posterior wall fracture

■ post-reduction CT to assess joint congruity and fractures

■ if reduction is unstable, put in traction x 4-6 wk

Question 10

Rochester method to reduce posterior dislocations

Answer 10

• Patient lying supine with hip and knee flexed on injured side
• Surgeon stands on patient’s injured side
• Surgeon passes one arm under patient’s flexed knee, reaching to place that hand on patient’s other knee (thus supporting patient’s injured leg)
• With other hand, surgeon grasps patient’s ankle on injured side, applying traction, while assistant stabilizes pelvis
• Reduction via traction, internal rotation, then external rotation once femoral head clears acetabular rim

Question 11

Complications for all hip dislocations

Answer 11

• post-traumatic OA
• AVN of femoral head
• fracture of femoral head, neck, or shaft
• sciatic nerve palsy in 25% (10% permanent)
• HO
• thromboembolism – DVT/PE

Question 12

Hip fracture clinical features

Answer 12

• acute onset of hip pain
• unable to weight-bear
• shortened and externally-rotated leg
• painful ROM

Question 13

Xray features of subcapital hip fractures

Answer 13

• Disruption of Shenton’s line (a radiographic line drawn along the upper margin of the obturator foramen, extending along the inferomedial side of the femoral neck)
• Altered neck-shaft angle (normal is 120-130°)

Question 14

DVT prophylaxis in hip fractures

Answer 14

LMWH (i.e. enoxaparin 40 mg SC bid), fondaparinux, low dose heparin on admission, do not give <12 h before surgery

Question 15

Femoral neck (subcapital) fracture definition

Answer 15

Intracapsular

Question 16

Femoral neck (subcapital) fracture mechanism

Answer 16

Young: MVC, fall from height

Elderly: fall from standing, rotational force

Question 17

Femoral neck (subcapital) fracture special clinical features

Answer 17

Same as general

Question 18

Femoral neck (subcapital) fracture investigations

Answer 18

Xray
AP hip
AP pelvis
Cross table lateral hip

Question 19

Femoral neck (subcapital) fracture complications

Answer 19

DVT

Non-union

AVN

dislocation

Question 20

AVN of femoral head

Answer 20

• Distal to proximal blood supply along femoral neck to head (medial and lateral femoral circumflex arteries)
• Susceptible to AVN if blood supply disrupted

Etiology: femoral neck fracture, chronic systemic steroid use, SCFE, Legg-CalvéPerthes, SLE, RA

Question 21

Intertrochanteric fracture stable vs unstable

Answer 21

Stable: intact posteromedial cortex

Unstable: non-intact posteromedial cortex

Question 22

Intertrochanteric fracture definition

Answer 22

Extracapsular fracture including the greater and lesser trochanters and transitional bone between the neck and shaft

Question 23

Intertrochanteric fracture mechanism

Answer 23

Same as femoral neck fracture Direct or indirect force transmitted to the intertrochanteric area

Question 24

Intertrochanteric fracture special clinical features

Answer 24

Ecchymosis at back of upper thigh

Question 25

Intertrochanteric fracture investigations

Answer 25

X-Ray: AP pelvis, AP/lateral hip

Question 26

Intertrochanteric fracture treatment

Answer 26

Closed reduction under fluoroscopy then dynamic hip screw or IM nail

Question 27

Intertrochanteric fracture complications

Answer 27

DVT, varus displacement of proxim l fragment, malrotation, nonunion, failure of fixation device

Question 28

Subtrochanteric hip fracture definition

Answer 28

Fracture begins at or below the lesser trochanter and involves the proximal femoral shaft

Question 29

Subtrochanteric hip fracture mechanism

Answer 29

Young: high energy trauma Elderly: osteopenic bone + fall, pathological fracture

Question 30

Subtrochanteric hip fracture special clinical features

Answer 30

Ecchymosis at back of upper thigh

Question 31

Subtrochanteric hip fracture investigations

Answer 31

X-Ray: AP pelvis, AP/lateral hip and femur

Question 32

Subtrochanteric hip fracture treatment

Answer 32

Closed/open under fluoroscopy, then plate fixation or IM nail

Question 33

Subtrochanteric hip fracture complications

Answer 33

Malalignment non-union wound infection

Question 34

Garden classification of femoral neck fractures

Answer 34

``` Type I Displacement none Extent incomplete Alignment valgus or neutral Trabeculae malaligned Tx internal fixation to prevent displacement (valgus impacted fracture) ``` ``` Type II Displacement None Extent Complete Alignment Neutral Trabeculae aligned Tx interal fixation to prevent displacement ``` ``` Type III Displacement some Extent complete Alignment varus Trabeculae malaligned Tx young - ORIF, elderly hemi/total hip arthroplasty ``` ``` Type IV Displacement complete Extent complete Alignment varus Trabeculae aligned Treatment young ORIF, elderly hemi/total hip arthroplasty ```

Question 35

Arthritis of the hip etiology

Answer 35

OA, inflammatory arthritis, post-traumatic arthritis, late effects of congenital hip disorders, or septic arthritis

Question 36

Arthritis of the hip clinical features

Answer 36

pain (groin, medial thigh) and stiffness aggravated by activity better with rest in OA * RA: morning stiffness >1 h, multiple joint swelling, hand nodules * decreased ROM (internal rotation is lost first) * crepitus * effusion * ± fixed flexion contracture leading to apparent limb shortening (Thomas test) * ± Trendelenburg sign

Question 37

Arthritis of the hip investigations

Answer 37

X-ray: weight-bearing views of affected joint ■ OA: joint space narrowing, subchondral sclerosis, subchondral cysts, osteophytes * RA: osteopenia, erosion, joint space narrowing, subchondral cysts * blood work: ANA, RF

Question 38

Arthritis of the hip treatment

Answer 38

• non-operative ■ weight reduction, activity modification, physiotherapy, analgesics, walking aids • operative ■ indication advanced disease ■ realign = osteotomy; replace = arthroplasty; fuse = arthrodesis • arthroplasty is standard of care in most patients with hip arthritis

Question 39

• complications with hip arthroplasty:

Answer 39

component loosening dislocation, HO, thromboembolism, infection, neurovascular injury, limb length discrepancy

Question 40

Hip dislocation post-total hip arthroplasty occurrence

Answer 40

occurs in 1-4% of primary THA and 10-16% of revision THAs

Question 41

Hip dislocation post-total hip arthroplasty risk factors

Answer 41

neurological impairment post-traumatic arthritis revision surgery substance abuse

Question 42

Hip dislocation post-total hip arthroplasty mechanism

Answer 42

THA that is unstable when hip is flexed, adducted, and internally rotated, or extended and externally rotated (avoid flexing hip >90° or crossing legs for ~6 wk after surgery)

Question 43

Hip dislocation post-total hip arthroplasty investigations

Answer 43

X-ray: AP pelvis, AP and lateral hip

Question 44

Hip dislocation post-total hip arthroplasty treatment

Answer 44

• non-operative ■ closed reduction: external abduction splint to prevent hip adduction (most often) • operative ■ indication: 2 or more dislocations with evidence of polyethylene wear, malalignment, hardware failure ■ revision THA ■ conversion to hemiarthroplasty with a larger femoral head ■ resection arthroplasty is a last resort

Question 45

Hip dislocation post-total hip arthroplasty complications

Answer 45

* sciatic nerve palsy in 25% (10% permanent) * HO * infection

Question 46

DVT prophylaxis in elective THA

Answer 46

(continue 10-35 d post-operative) Fondaparinux, low molecular weight heparin, or warfarin