Wordings Flashcards
1
Q
CTEV
A
I am going to manage the patient according to Ponseti technique which depends on two biomechanical concepts to get a correction.
- First one is the using the viscoelastic property of tendons and ligament using the creep
- kinematic coupling in the movement of the foot and ankle.
My aim of the treatment is to achieve strong, painless, plantigrade and supple foot.
- Kinematic coupling - when is the joint is in the oblique plane as with subtalar joint all the motion is inextricably linked to one another or kinematically coupled The varus of the calcaneus can’t happen n without concurrent abduction/adduction of the forefoot.
- Creep - slow and progressive permanent deformation of a material with time and under constant stress.
- Pirani scoring - six components 0.5 , 1, 1.5 , Hindfoot and midfoot scores X rays - resistant and relapse or teratologic TC angle - AP / Lat 20 - 40 degrees
2
Q
CTEV
A
- Outline the Ponseti regimen
- Serial casting of the lower limb using a strictly defined technique and wkly change of the cast.
- Percutaneous tenotomy
- Foot Abduction orthosis( Denise Brown Splint) for first 3 months and night time up to age of 4-5 yrs
- If there is dynamic supination - split transfer of tib ant
- No attempt should be made to actively dorsiflex until The talar head is covered, usually NO midfoot contracture
- The foot is abducted to 50-70 degrees The heel is in or neutral
- Results of the Ponseti technique - the key paper
3
Q
PIN for SUFE - How would you do
A
- Appropriately consented and marked, IV Abx No formal manipulation, increase AVN Traction table.
- Entry point - both AP and lateral Anterior entry point Center - Center in the head,
- Perpendicular to the physis If not can hit the ascending cervical artery posteriorly DO not enter the joint, dye to confirm not penetrated the joint. 3-4 threads
- The starting point should not be medial to the intertrochanteric line - will result in impingement between the head of the screw and acetabulum with hip flexion screw position advance until 5 threads cross physis < 5 threads engaged in epiphysis increases risk of progression of slip >10° (<5 threads 41% progressed, >/= 5 threads 0% progressed) screws should be at least 5mm from the subchondral bone in all views Obligatory external rotation
4
Q
Valgus knee
A
- Surgical Approach
- Bone cuts
- Distal femur - 3degrees to compensate for remodelling
- Minimal femoral resection
- Tibial resection - perpendicular to mechanical axis 5-8mm off medial side , minimal / no lateral resection
- Rotation - posterior condylar referencing - inaccurate, tendency to IR femur component.
- Increase in Q angle and abnormal patellar tracking
- Whiteside’s line and Intercondylar Eminence line
- Soft tissue balancing
- Tight lat side - two types LCL and Polpliteus tendon - inserted at flexion and extension axis , isometric in extension and flexion of knee
- IT band , lat capsule and lat head of gastroc - act only in extension
- Ranawat inside-out technique - knee is extended and laminar spreader and palpate the tight structure laterally , Structures released - PCL , PLC , IT band ( multiple stab incision , one cm proximal and higher to the tibial cut )
- Tight in flexion - popleateal released
- Still not balanced - MCL advancement , MCL imbrication
- Patellar tracking
- release the tourniquet
- Lateral release - inside out technique - lat retinaculum is exposed and retinaculum is exposed and incised from mid patellar level to the upper tibial border 1 cm lateral to patella.
- Component selection - PS preferred and PCL in non functional
- Greater lateralisation of component with better patellar tracking
- Some degree of stability because of CAM POST mechanism
- Significant deformity - VVC or hinged knee , component augmentation
- Complications -
- Residual instability
- Recurrence
- Common peroneal nerve palsy due to traction ( 3-4%)
5
Q
Design a perfect plate
A
- The design of my implant consider many factors
- Modality of use
- Precontoued plate
- Fragment specific plate
- Primary vs secondary
- Anatomical reduction vs alignment
- Rigid vs relative stabilisation
- Load sharing vs load bearing
- Combination
- Straight locking vs variable angle
- Material property -
- bioinert, reliable, easily manufactured and sterilisable
- Youngs modulus elastic/ plastic
- Yield point Brittle- Ductile Toughness Hardness
- Structural property - depends on shape of the material
- Bending stiffness
- Torsional stiffness
- Axial stiffness
- Interface fixation -
- conventional
- locking plate or combination preservation of blood supply
- Stainless steel 316L — Low carbon - less corrosion, cheap
- TiAl 64V - self pacifying, youngs modulus is equal to the bone, CoCR
6
Q
Triplane fracture
A
Transitional fracture Differential ossification
7
Q
MRIa
A
Nuclear spin Precession - Magnatisation vector TR TE
8
Q
femoral stem
A
- double / triple Tapered highliy polished Forced closed - controlled subsidence
- Creep of cement hoop stress prevent stress shielding centraliser Cement -cement
9
Q
Pavlic harness
A
- stable concentrically reduced hip which prevents development of arthritis of the hip
- Pavlik harness is a dynamic flexion abduction orthosis used to treat DDH in infants up to 6 months of age
- harness usually leads to stability of reduced hip w/ in 4 wks, but its use should be continued until clinical exam &x-rays of hip are normal
- harness consists of chest strap, 2 shoulder straps, & 2 stirrups
- each stirrup has an anteromedial flexion strap &posterolateral abduction strap
- harness is applied with the child supine
- chest straps: - chest strap is applied first, allowing enough room for hand to be placed between the chest and the harness
- shoulder straps are buckled to maintain chest straps at nipple line
- these should not be applied distal to nipple line
- stirrups: feet are then placed in the stirrups one at a time
- anterior strap: hip is reduced in flexion (90 to 120 deg), & anterior flexion strap is tightened to maintain this position
- transient femoral nerve palsy has been reported w/ hip flexion greater than 120 deg; - ref: Femoral Nerve Palsy in Pavlik Harness Treatment for Developmental Dysplasia of the Hip
- lateral strap: lateral strap is loosely fastened to limit adduction, not to force abduction (knees should be 3-5 cm apart at full adduction in harness); - posterior strap: - will maintain hip in safe zone but must not to force hip into abduction (to avoid the rare complication of AVN)
- posterior straps should not be overtightened; - knees should be able to come together to w/ in 3 fingers width or should come to within 3-5 deg of the midline;
10
Q
Impediments to Reduction in DDH
A
- Intra articular
- Extraarticular
soft-tissue impediments to adequate reduction include: -
- constriction of the joint capsule of hip: most important type of obstruction in older children;
- contraction of the psoas tendon over acetabular inlet
- hypertrophy of the transverse acetabular ligament
- pulvinar, or the ligamentum teres; -
- as children reach walking age, hypertrophy of the ligament may preclude hip reduction unless ligament is excised;
- inverted neolimbus: - rare type of obstruction in DDH; - formed when dislocated femoral head is above or behind labrum
- lip of hypertrophied fibrocartilage may be infolded or everted
- may be adherent to hip capsule or supra-acetabular iliac wall;
11
Q
The ultimate goals of tibial pilon fracture management are
A
- restoring an anatomic articular surface,
- restoring mechanical alignment
- maintaining joint stability
- achieving fracture union
- regaining functional and pain-free weight bearing and motio
- while avoiding complications
12
Q
Tibial Pilon Reduction sequence
A
Fragments
- anterolateral
- medial
- posterolateral fragments,
- with a central component that may be significantly comminuted.
- With open approaches, the reduction sequence (after fixation of the fibula in many cases) begins posteriorly and then progresses medially, followed by central reduction, and finally the anterolateral fragment
