Scott Oral Exam Prep Flashcards
Outline your algorithm for dealing with neuromonitoring changes.
Gain control of the room
Pause case, announce to room
Remove distractions (music, etc)
Summon staff anesthetist, neurophysiologist, nurse.
Anticipate need for imaging.
Systemic/Anesthetic
Optimize MAP, Hb, pH, CO2, Temperature
Discuss potential need for wake up test
Technical
Verify anesthetic agent; presence of paralysis
Check electrodes & connections
Patient positioning
Timing and pattern of signal changes
Surgical
Remove traction, rods, screws
Probe screw holes PRN
Check osteotomy/laminotomy sites for compression
Imaging to confirm implant position
Ongoing
Wake up test if signals not improved
Reassess anesthetic/systemic issues
IV methylprednisolone 30mg/kg first hr, then 5.4 mg/kg/hr for 23 hrs.
MRI or CT myelogram
Consult with a colleague
Consider staging procedure. If spine unstable, remove any concerning screws, leave rods and spine in uncorrected position.
List three instances where one need not repair a dural tear.
Outline the postop protocol for a dural tear not repaired.
- Dura torn but arachnoid membrane intact
- Non repairable due to minimally invasive technique
- Anterior/inaccessible location
Bed rest 48 hrs then stand up test.
OK? Then get MRI at 6 mos
Headache? One more day of bed rest.
Consider return to OR for repair if still no better.
Outline intraop management of dural tear
RISK FACTORS: Revision surgery, OPLL, surgeon inexperience, connective tissue disorder, older patient
Visualization
Position in reverse Trendelenburg
Lighting/headlight/loupes
Decompress more bone PRN
Suction with cotton pledget
Hemostasis (bipolar; fibrin glue; gelfoam; surgicel)
Repair
Ensure no rootlets extruded
4-0 or 5-0 nylon running closure of dura (watertight)
Fibrin glue sealant
Valsalva to test integrity of repair.
Patch if not repairable (lumbodorsal fascia or fascia lata patch)
Watertight closure in layers.
Consider subfascial drain if valsalva causes leakage
Postop
Antibiotics for duration of drain
Bedrest for 48-72 hrs (Standup test)
Persistent drainage? Get IR or NSx to insert subarachnoid lumbar drain above durotomy. No more than 400 cc per day (clamp if >400cc in 24hrs)
Remove drain at 48 hrs.
Differential Diagnosis of bone lesion in children <5
Benign
Osteofibrous dysplasia
Osteomyelitis
LCH
Malignant
Leukemia
Metastatic rhabdomyosarcoma
Metastatic neuroblastoma
Differential for bone lesions in patients <30
Benign
LCH, Fibrous dysplasia, osteofibrous dysplasia, osteoid osteoma, osteoblastoma, chondroblastoma, UBC, ABC, NOF, Osteomyelitis
Malignant
Ewing’s, Osteosarcoma, Leukemia
Differential for bone lesions in patients >30
Benign
GCT, Brown’s tumour (hyperPTH), Paget’s
Malignant
Mets, Multiple myeloma, Lymphoma, Chondrosarcoma, Chordoma,
Paget’s and postXRT sarcoma
List principles of biopsy
Preop:
Have pathologist available
Labs (CBC, plts, INR)
Do in definitive treatment centre
Intraop:
Tourniquet on, don’t inflate
Longitudinal/extensile incision which can be incorporated into definitive resection
Meticulous hemostasis
Avoid creating/dissecting planes
Avoid neurovascular structures
Biopsy through single muscle compartment
Biopsy the soft tissue mass if possible
Bone biopsy - oval window
Send tissue for both frozen AND culture/sensitivity
If using drain, bring out in line w/ incision
Differential Diagnosis for multiple bone lesions
List benign/malignant
Benign:
Polyostotic FD, LCH, Multiple enchondromatosis, Multiple exostoses, Brown tumour, Paget’s, multifocal osteomyelitis
Malignant:
Mets, Multiple myeloma, Multifocal osteosarc
DDx for lesions in the sacrum
Midline:
Chordoma
Eccentric:
ABC, GCT, Mets, Chondrosarcoma
(Recall: Chordoma is S100 and keratin positive)
Investigations for metastatic disease
Prostate PSA
Thyroid U/S
Breast Mammogram
Lung CXR or CT Chest
Kidney CT abdo
MM SPEP/UPEP/Skeletal survey
Lymphoma CT C/A/P
Dr Holt mnemonic for diaphyseal lesions Ddx
A: adamatinoma
E: Eosinophilic Granuloma
I: Infection (osteomyelitis)
O: OO or OB
U: Ewing’s
Y: Myeloma, Lymphoma, Fibrous dYsplasia
METS
List 4 tumours treated with wide resection alone.
Chondrosarcoma
Chordoma
Parosteal Osteosarcoma
Adamantinoma
Benefits of gadolinium enhancement of MRI
Abscess will show peripheral enhancement
Can identify cystic/necrotic areas of a tumour
Pattern of enhancement can suggest benign vs malignant lesion
Pattern of enhancement can identify aggressiveness of vascular/lipomatous lesions
Outline your follow up plan for Soft Tissue Sarcomas
Visits q 3mos for a year
q 6 mos for 5 years
then yearly until 10 years
Physical exam and CXR at each visit
Lesions treated with chemotherapy and wide resection
Osteosarcoma
Periosteal osteosarcoma
Ewing’s Sarcoma
MFH of bone (fibrosarcoma)
Dedifferentiated Chondrosarcoma
Mesenchymal Chondrosarcoma
Rhabdomyosarcoma
Synovial Sarcoma
Describe 2 techniques for hip arthrodesis
- Watson Jones, anterior capsulotomy to denude cartilage, take off vastus lateralis, fix with 150 degree DHS and a few large cancellous screws. Postop spica.
- Smith Pete (modified). TFL/Sartorius plane. Watch for LFCN. Need to detach sartorius off ASIS and rectus of AIIS. Modification includes elevation of the abdominal muscles off the crest to subperiosteally expose the inner table (elevate iliacus) back to the SI joint. Femoral exposure is done by lifting vastus lateralis off from lateral to medial (to protect innervation). Must tie off ascending LFCA. Anterior capsulotomy (T) to denude cartilage. Insert a single lateral lag screw across the joint into superior acetabulum. Then a 12-14 hole large frag plate precontoured. Plate starts just lateral to SI joint to get good screws in PSIS bone. Contour to pelvic brim and down the femur. Can use compression device.
Position: 20-30 flexion, 0-5 adduction, 0-10 of ER
Costs 30% more energy expenditure
3 techniques for knee arthrodesis
Positions is 5-8 of valgus, 0-20 of flexion, and ER to match the other side (check preop).
- Retrograde/antegrade short nail (ie Wichita)
Benefits of less blood loss, no fem/tib mismatch and less breakage. Standard anterior approach and prep of surfaces. Ream and size tibia first (will be limiting size as tibia is smaller). Lock prox and distal with jig, compression with wrench. Bone graft PRN. Don’t incorporate patella if you plan to revise to TKR later. Zimmer/cast for 6/52. I will WBAT.
- Long antegrade nail (piriformis start)
- Dual compression plating. Options are medial/lateral or medial/anterior. Large frag contoured plates. 4 screws above and below.
4 ways to assess for normal joint line position in revision TKR
2 finger breadths above tibial tubercle
15mm above fibular head
3cm distal to medial femoral epicondyle
Look for old residual meniscus rim during surgery
**Just get an xray of the other side to compare. Note the height of the joint line above the fibular head**
6 intraop considerations for revision TKR
Exposure (and need for snip, turndown, osteotomy etc)
Safe removal of components
Addressing bone loss defects
Fixation of new revision components
Restoration of joint line
Balance of ligaments (and extra constraint PRN)
SONK vs secondary osteonecrosis of knee?
SONK
Older patient (>55), usually female
Usually unilateral medial femoral condyle
Tx: Nonop, then UKA or TKA if fails to respond
Spontaneous osteonecrosis
Younger (age <55), usually female, 80% bilateral
Risk factors often present
Pain when going from sit to stand
Tx: Nonop, vs allograft vs arthroplasty
DDx for painful THA with positive xray findings
(ie things that can be seen on xray)
Aseptic loosening
Septic loosening
Osteolysis without loosening
Micromotion
HO
Stress shielding
DDx for painful THA with negative xray
Reactive synovitis
ALVAL or Pseudotumour
Metal Hypersensitivity
Prosthesis impingement
Iliopsoas irritation
Gluteus medius tear
Nerve injury
GT bursitis
Inguinal hernia
Referred pain (intrapelvic or L spine)
What is the Dorr ratio?
Dorr calcar to canal ratio. Used to determine whether uncemented femoral component is appropriate.
Measure canal width at midpoint of LT, then 10cm distal.
A: <0.5
B: 0.5-0.75
C: >0.75 (AKA stovepipe)
How to identify the anatomic hip centre?
Ranawat’s Triangle
Measure pelvic height (horizontal lines at top and bottom of pelvis)
Draw vertical line thru a point “A” 5mm LATERAL (yes) to the intersection of Kohler’s and Shenton’s lines.
Draw another perpendicular line above “A” 20% of pelvic height. The length of this line should also be 20% of pelvic height.
Connect the triangle. Hip centre is the middle of the hypoteneuse.
Issues to mention for DDH arthroplasty.
Acetabulum
Soft bone; restore hip centre; smaller component; try for >50% host coverage; alternate bearing surface
Femur
Smaller canal, modular components for version; don’t over lengthen; posterior GT location
Equipment to ask for in DDH hip case
Smaller components (DDH components)
Modularity
Alternate bearing surfaces
Intraop xray
Structural allograft or augments
Consider TM shell or cluster shell for screws
Fixation for subtroch osteotomy (cables)
Describe interval for Ludloff approach
Superficial
Between gracilis and adductor longus (both supplied by anterior division of obturator nerve)
Deep
Between adductor brevis (anterior division of obturator nerve) and adductor magnus (dual innervation by posterior division of obturator and tibial nerve)
Pros/Cons of different bearing surfaces.
Metal on Poly
Ceramic on ceramic
Metal on Metal
MoP
Lowest cost, long track record, most options
Highest risk of particle induced osteolysis, higher wear rate
CoC
Lowest wear rate, inert particles
High cost, risk squeaking, risk of fracture (brittle), fewer options for size
MoM
Low wear rate, large head size allows for inc ROM
Metal debris/reaction/sensitivity, bad for CRF/child bearing females, higher cost.
Arthroplasty issues specific to Paget’s disease
Preop:
Treat with bisphosphonate first
Anesthesia: high output cardiac failure
Make sure to rule out Paget sarcoma
_Intraop_: Blood loss (be prepared)
Deformity (may need osteotomy, cemented fixation)
Protrusio (in situ neck cut, medial bone graft)
Postop:
HO prophylaxis
Structures at risk with acetabular screw placement (by quadrant)
Posterosuperior (max screw length 45mm)
Sup gluteal nerve/artery
Sciatic
Posteroinferior (max screw length 20mm)
Inf gluteal nerve/artery, internal pudendal artery
Anterosuperior
External iliac vessels
Anteroinferior
Obturator vessels
Zones of loosening THA
Acetabulum
Charnley zones (1: sup 1/3; 2: middle 1/3; 3: inferior 1/3)
Stem
Gruen zones
AP 1-7 (1 is GT, 4 is tip, 7 is LT)
Lateral 8-14 (8 is anterosup, 14 is posterosup)
Outline forequarter amputation
Anterior incision starts 2cm lateral to SC joint. Superior limb over the AC joint, inferior limb beneath axillary hair. Posterior limb behind shoulder.
Anterior work
Release clavicular head of pec major. Osteotomize clavicle lateral to SCM insertion. Release muscles off clavicle. Double ligate and divide subclavian vessels and plexus (traction).
Release Pec major and Lat Dorsi off the humerus. Release muscles off coracoid process.
Posterior work
Release skin flap off AC joint, acromion and superficial surface of scapula.
Release musculature off scapula (trapezius, omohyoid, levator, rhomboids, serratus). Arm is now free.
Suture pec, lats, traps, serratus over the chest wall. Trim skin flaps. Close over a drain.
Outline posterior flap external hemipelvectomy.
Position semi-supine with roll under side of trunk to prop up the patient.
Anterior
Incise along crest and along inguinal region to the symphysis. Sharply release abdominal musculature the whole way from PSIS to ASIS and on to symphysis. Protect spermatic cord/round ligament. Develop retroperitoneal approach back to the SI joint. Double ligate common iliac vessels. Ligate femoral nerve. Divide psoas muscle above the pelvis.
Perineal
Assistant abducts and flexes the leg. Continue incision from symphysis along the ischium. Disarticulate the symphysis. Protect bladder and urethra with malleable retractor. Develop ischiorectal space.
Posterior (may need to place patient in lateral position)
Skin incision continues laterally along gluteal crease and then heads anteriorly and superiorly to the ASIS. Elevate the full thickness flap back to the SI joint.
Carefully divide pelvic floor muscles off hemipelvis from ischium back to SI joint. Ligate sciatic nerve. Assistant holds the leg in abduction and flexion.
Disarticulate SI joint. Close over drains.
*** Can also do modified version where G Max left as part of flap. Osteotomize the ilium lateral to GMax origin ***
Outline hip disarticulation
- Apex of incision starts at 2cm medial to ASIS. Continue medially & distally through medial perineum and 2cm distal to ischial tuberosity, then 2cm distal to gluteal crease. Go posteriorly and laterally around leg then head back towards ASIS passing about 2cm anterior to GT.
- Will have to ligate the saphenous vein, superficial epigastric and multiple external pudendal vessels. Expose the femoral triangle. Double ligate the femoral artery then vein. Traction then ligate the femoral nerve.
- Release sartorius off ASIS then iliopsoas off LT.
- Gracilis, adductors and pectineus released off of pelvis. Must ID and ligate obturator vessels and nerve bifurcating around adductor brevis. Release obturator externus from the femur (leave attached to pelvis!)
- Hyperabduct the leg. Release hamstrings off the ischial tuberosity. Capsulotomy and cut the ligamentum teres.
- Adduct the leg. Divide Gmax and TFL in line with skin incision. Release Gmax, abductors and short external rotators off femur. Dissect sciatic, traction and divide to allow it to retract into pelvis.
- Sew gluteus medius and obturator externus over the acetabulum to reduce bony prominence. Approximate iliopsoas to quadratus femoris to reduce dead space.
- Sew gluteal fascia to the inguinal ligament and the pubis. Interrupted skin closure with drain inserted deep to gluteal fascia. Compressive dressing for 3-5 days.
Open approach to TFCC repair (type 1B)
Incision b/w 5th and 6th compartments
L shaped DRUJ capsulotomy (protect dorsal radiocarpal ligament)
Transverse ulnocarpal capsulotomy.
Debride fovea
Small K wire to make drill holes in dorsal ulnar neck exiting into fovea. 2-0 suture to repair TFCC to fovea, tie over ulnar neck.
6 weeks LAC then 2 more SAC.
Recall classification: 1A central tear, 1B ulnar avulsion, 1C distal avulsion off carpus, 1D avulsion off radius
Chronic DRUJ instability
Adams procedure
Dorsal incision between 5/6. L shaped DRUJ capsulotomy. Volar-ulnar approach for retrieval.
3.5 mm drill hole in distal radius, 5mm from both lunate facet and sigmoid notch. 3.5mm drill hole in ulnar neck into fovea.
Palmaris graft thru radius, into fovea, out the neck and around radial neck. Tie off and suture in reduced DRUJ position.
Can add sigmoid notch osteoplasty PRN.
Long arm immobilization for 6 weeks then short-arm for 2 more weeks.
Ulnar stabilization after Darrach
Breen-Jupiter technique
Proximally based strip of ECU
Distally based strip of FCU
Thru drill holes/canal
Modified Brunelli
(for stages 3 and 4)
Must be irreparable and reducible
Dorsal approach. Fibre splitting capsulotomy.
Check reducibility of SL articulation with traction or joystick pins.
Dorsal transverse trough in lunate with burr or rongeur, suture anchor in trough.
Drill hole thru long axis of scaphoid. Harvest 3-4mm wide distally base strip of FCR about 8cm long. Bring volar to dorsal thru the scaphoid.
Bring tendon thru pulley of dorsal radio-triquetral ligament.
Tension everything and insert SL and SC pins. Tie suture anchor in lunate, tie loop of tendon to itself.
Technique for midline lateral Lumbar discectomy
(Paracentral disc)
- Usual preop stuff, IV abx, xray to landmark, display preop xrays in the room.
- Prone position Wilson frame, belly hanging free.
- Midline incision 3-4cm. Incise midline fascia paramedian to the interspinous ligament. Subperiosteal dissection to expose posterior aspect of lamina and facet joint. Don’t violate facet capsule. Need to see intralaminar space as well as half of cranial and caudal laminae.
- ***Kocher on the SP and get another xray now***
- Use Kerrison to remove inferior edge of cranial laminae and strip the ligamentum flavum.
- Identify thecal sac. Bipolar cautery for venous plexus. Identify exiting nerve root and dissect any adhesions.
- Retract thecal sac/nerve root medially and remove disc fragment. May incise PLL to enter disc space and remove any loose fragments to prevent recurrence. May need to explore laterally in foramen or inferiorly in the root axilla.
Add some topical steroid.
Closure.
Techinique for transmuscular far lateral discectomy
- Preop IV abx, xray in the room, display preop films.
- Prone position Wilson frame on Jackson table, belly hanging free to reduce venous congestion.
- Check level with flat plate.
- Incision 3-4 cm long, about 3-6cm from midline.
- Incise fascia, bluntly separate multifidus and longissimus. Expose isthmus, TP above and below, facet joint.
- Detach intertransverse ligament
- Burr/kerrison to remove crescent of bone from superior isthmus and inferior aspect of cranial TP. Kerrison away the lateral ligamentum flavum.
- Visualize and protect the nerve root and DRG. Resect disk fragments (usually medial and inferior to the nerve root). Can incise disk space to do limited discectomy.
- Closure
Gallie wiring technique
Skin incised from EOP to C45 level
Careful subperiosteal dissection of C1 arch and C2 SP/lamina
Decorticate under arch and above C2 SP/Lamina.
Need to notch undersurface of C2 SP with burr.
Wire looped anterior to C1 arch, loop brought inferior to the C2 SP. Tuck in the crest cortical graft. Free ends of wire crossed over graft and tied to secure.
C1 C2 fixation pearls
C1 lateral mass screw
Start point at the lateral mass underneath where the arch meets the lateral mass. Protect C2 root. Aim slightly medial and superior (<10degrees). Can check lateral fluoro to gauge the amount of sagittal angulation. Want UNIcortical purchase. Can use penfield 4 to palpate medially to ensure no breach.
C2 screws
Pars: Inferior start point, midpoint of the C2/3 facet joint. 10-15degree medial angulation. Lateral fluoro to check sagittal angulation. Usually 12mm screw
Pedicle: Superior start point (in line with top of C2 lamina). More lateral start than pars screw, aim about 20-25deg medial. Slight upward sagittal trajectory but not as much as a pars screw. Usually 20-24 mm screw.
Transarticular
Inferior start in C2 but a bit more medial than pars screw. No med/lat angulation. Use lateral fluoro to gauge the sagittal angulation but aiming at the anterior tubercle of C1. Usually 40mm length.
In picture, purple is transarticular, green is pedicle and blue is pars.
Odontoid screw technique
Usually R side, transverse incision at C5 level.
Dissect medial to SCM and the Carotid sheath, lateral to trachea and esophagus.
Reach the prevertebral fascia at C5, dissect upwards. Identify C2-3 disc space on xray.
May need partial discectomy midline to expose anteroinferior start point on C2.
Drill K wire under biplanar fluoro into the fracture. Measure screw length and insert cannulated, partially threaded screw. Verify position on biplanar fluoro.
Posterior cervical foraminotomy technique
3mm burr to decompress the lamina above and below the nerve root. Lateral extent is the medial 1/3 of the facet joint. Use kerrison to remove the ligamentum flavum medially.
Picture shows decompressed nerve root
Magerl technique for subaxial lateral mass screws
Start point
1 mm medial to centre of LM
1-2 mm cephalad to centre of LM
Direction
Aim 25 degrees laterally
Aim 30 degrees superiorly (or parallel with superior articular facet on lateral xray)
