‘Bone Joint and Nerve Clinic’ was started in the year 2018 by one of the Best Orthopaedic Surgeons in Patna, Dr. Neeraj kumar.
To establish the centre of excellence in Orthopaedics Dr. Neeraj kumar focused on its specialities by providing a safe & secure environment and performed the duties with utmost competency through utilising effective and innovative clinical practices with profound academic research.
post traumatic osteoarthritis of hip ( acetabular fracture, neck of femur fracture)
Implant selection
Biomechanics of THR implant relies on prosthesis design, bearing surface and type of fixation (cemented vs uncemented)
THR components include
femoral component
cemented
uncemented (press-fit) High cost, difficult to control version, calcar fracture,
Modular stem
taper stem
extensively porous coated stem
Acetabular component
cemented
uncemented (press-fit)
Bearing surface
polyethylene
metal
ceramic
Type of fixation
Cement(PMMA)
Biological fixation( uncemented) – young, older patient with good bone quality and in revision THR
bone ingrowth- bone grows into the porosity of implant
bone ongrowth- bone grows onto the divots in the implant
Depuy Charnley 10A
22.2mm mono-block stainless steel head and stem
Matt-finish
stability depends on strong bonds between bone and implant
Stress shielding in proximal femur
Collared to prevent stress shielding
Exeter(Stryker)
Double taper stainless steel
Modular
Self locking sliding per or forced-closed design
Subsidence 1.5 mm in 12months
no neck collar
CPT stem (Zimmer)
Collarless, polished, Tapper stem
similar to Exeter
Made of cobalt chrome or stainless
C-Stem(Depuy)
Triple taper and thicker laterally.
Loads medial cement mantle
Produces proximal bone remodelling
Stanmore(Zimmer)
Similar design to charnley.
S-ROM stem(Depuy)
revision stem
distal fixing modular uncemented stem
Restoration Stem (Stryker)
modular revision stem
Imaging
X-RAY AP and frog leg lateral view of both hips done in 15 degree of internal rotation
CT scan as prep planning if there is protrusio acetabulum or bone loss
MRI in case of AVN of hip
Alignment view of both limbs
Xray ls spine to rule out referred pain from degenerative spine
Templating of femur and acetabulum
Horizontal line connecting two tear drops
Determine the centre of rotation
Appropriate size femoral stem to fill medullary canal
Approach
Minimally invasive THR
No added advantage over convention in RCT
B/L THR has increased infection rate and increased chances of bleeding
Head sizing
Skirted vs non skirted decreases the range of motion and head neck ratio so should be avoided
Small vs large head – 22.2mm vs 28mm vs 32mm, large head give more range of motion and decreases dislocation rate due to increased head and neck ratio.
Bearing surface
Metal on poly
metalic (cobalt chrome) femoral head on polyethylene acetabular liner
longest track record, low cost and most modular
High wear rate and osteolysis
revision rate 5% in male and 3% in female at 15 years in 75 years age group
Ceramic on ceramic
Best wear properties
Inert particle
expensive
Squeaking
low rate of revision 5.6% in male and 4.3% in female
Ceramic on poly
reduced fracture and squeaking risk
revision in male 2.3% and 2.9% in female at 15 year follow-up in 75 years age group.
Metal on metal
better wear properties than metal on poly
type 4 hypersensitivity
increased metal ions in urine and serum
Acetabular cup
Cemented cup
All poly
thicker poly can be used for reduce stress transmission on the cement mantle
commonly used cups are Exeter rimfit/contemporary, ZCA ally poly cemented cup Zimmer and marathon (depuy)
Uncemented cup
Trident stryker available in hemispherical shell with multilocking hole option and peripheral self locking option
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