Knee Surgery

Question 1

Causes of knee haematoma

Answer 1

1. Fracture
2. Ligament injury
3. Meniscal tear
4. Patella dislocation

Question 2

Classification for periprosthetic infections - THR OR TKR

Answer 2

Tsukayama JBJSA 1996

1) Acute - < 4weeks - Liner exchange
2) Chronic - 4 weeks to 2 years - 2-stage
3) Acute Hamatog - > 2 years - 2 stage
4) Positive intraop cultures - 6/52 IV Abx

Question 3

What are my Indications for HTO?

Answer 3

1 - Age < 55. 2- Weight < 90kg
3- Uni OA - Clinical and Rx. 4- Aysymptomatic PFJ OA
5- Range  90 flexion
6- Varus < 10
7- Subluxation < 1cm
8- No thrust
9- Stable knee
10- Non RA / Inflamm
Smoking is relative CI - Increased non-union so closing more than opening wedge

Question 4

What are the Coventry indications for HTO?

Answer 4

1- age < 65 
2- Pain correlated with medial Rx findings
3- Rx normal lateral compartment
4- Range  90 flexion
5- Varus < 15
6- Stable knee
7- Internal derangements excluded 

Coventry - Acta orthopaedica Belgium 1982

Question 5

Classification for femoral periprosthetic TKR #

Answer 5

Rorabeck and Lewis
Type 1 - non-displaced and stable
Type 2 - displaced and stable
Type 3 - unstable

Stable prosthesis - use Su classification
Type 1 - # above femoral component
Type 2 - # at level of femoral component.
Type 3 - # below level of component

Question 6

What studies looked at notching on femurs causing PP TKR #s

Answer 6

Lesh - JBJSA 2000
3mm anterior notch is 30% decrease torsional strength

Healing, remodelling and stress distribution

Ritter 1988 JofArth
670 TKR - 27% with notching

Question 7

Risk factors for PP TKR #

Answer 7

Patient

• age
• osteopaenia
• RA
• neurological disorder
• steroids
• loosening / lysis
• infection

Surgical

• notching
• malalignment
• increased constraint
• revision
• devascularization
• excessive resection

Question 8

Classification for tibial PeriProsthetic TKR #

Answer 8

Felix
Type 1 - tibial plateau
Type 2 - adjacent tibial stem
Type 3 - distal tibial stem
Type 4 - tibial tubercle

Question 9

Classification of patellar PeriProsthetic TKR #

Answer 9

Ortiguera and Berry

Type 1 - ext mech Intact & stable
Type 2 - ext mech disrupted - stable or unstable
Type 3 - EM intact, unstable, good bone stock
Type 4 - EM intact, unstable, poor bone stock

Question 10

Causes of a Valgus knee

Answer 10

Congenital - dysplasias

Acquired
SONK
Meniscectomy
Trauma - Cozens, physeal, mal union
Lateral OA / RA

Question 11

Risks of infection in ACL surgery

Answer 11

1. 9 times if previous knee surgery
2. 1 times is prior surgery was an ACL

Hamstring graft 1.4% risk vs 0.5 for BTB or allograft
Possibly - superficial fixation on post, high suture load, extra ST dissction

Limit infection - foot on sterile are at all time, graft from trusted site and always in secure area of OT, waterproof drapes, limit OT traffic

Question 12

Pattern of OA in PCL deficient knee

Answer 12

80% Medial femoral condyle and 50% Patella after 5 years