TOTAL KNEE REPLACEMENT

11 Oct TOTAL KNEE REPLACEMENT

Posted at 09:10h in Uncategorized by drneerajkumar 0 Comments

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INDICATION

Pain
loss of function
Deformity

CONTRAINDICATIONS

Infection
Extensor mechanism
Precious arthrosis
Poor muscle power and ligaments
Limb ischemia
Charcots joint(neuropathic joint)

X-RAYS

weight bearing PA(Rosenberg view)
lateral in 30⁰ of flexion
Skyline
alignment view both lower limb

MANAGEMENT OF OSTEOARTHRITIS

Conservative
- Non surgical alternative method should be exhausted before surgical management.
  - weight loss BMI > 30 has high complication rate and poor survivorship
  - Physiotherapy
    - low impact aerobic exercises with quadriceps and hamstring strengthening
  - Brace
    - if varus/valgus correctable on passive stretching and if only one compartment is involved
    - Varus/valgus offloading brace
  - Intra-articular steroid injection
    - to reduce joint inflammation
    - increase viscosity of synovial fluid
    - TKR to be after 3 months of injection
  - Hylan injection- total three injection over 3 weeks of 3ml OR one injection of 6ml. INJ HYLAN VS STEROID – no difference
  - young patient – joint distraction
  - topical NSAID, TENS/IFT, THERMOTHERAPY – recommended
  - Arthroscopic lavage if meniscal tear
Surgical
- Technical goal of TKR
  - limb alignment
  - restoration of joint line
  - soft tissue balancing
  - ROM restoration
  - Matched rectangular flexion and extension gap
  - Restoration of Q angle
  - rigid durable low contact stress fixation
- choice of implant and long term survival
  - 90% survival rate at 10 years follow-up
  - Press fit condylar knee sigma (Depuy)
    - 3.18% for CS at year follow-up
    - 4.24% for PS at 15 year follow-up
  - Other implants
    - Triathlon(stryker)
    - scorpion(stryker)
    - genesis 2(smith ans nephew)
    - vanguard knee system
    - Nexgen(Zimmer)
  - Cemented had improved survivorship compared to uncemented.
Approaches
- Medial parapatellar
- Lateral parapateller
- Mid-vastus
- sub-vastus
- Extensile V-Y turn down and quadriceps snip and tibial tubercle osteotomy in case of quadriceps contracture, weak quadriceps and in revision cases
- use lateral most incision if there are multiple scars
- navigation/computer aided better alignment correction with computer aided than conventional method
- Minimal invasive vs conventional approach – no advantage of minimal invasive
Surgical considerations
- Femoral design
  - Single radius
  - Double radius
  - cruciate retaining
  - posterior stabilized
  - Anterior stabilized
  - Constrained non-hinged
    - large central post and deep femoral box
    - varus/valgus instability
    - in obese patient BMI > 35
  - constrained hinged
    - FEMUR AND TIBIA CONNECTED BY A BAR
    - Multi-ligament deficiency
    - polio
    - massive bone loss
    - in case of tutor or infection
  - No significant difference between all designs and are indicated in different cases.
  - Anterior vs posterior referencing
- Femoral preparation
  - intramedullary alignment by whiteside line.
  - Valgus cut of 5 to 7 degree to get a femoral cut perpendicular to mechanical axis of femur
  - size the femur(Ant. Vs Post. referencing)
  - Posterior condylar cut in 3 degree internal rotation with respect to epicondylar axis, so jig referencing from posterior condylar axis has a in-built 3 degree external rotation for posterior femoral cut.
  - Asymetric bone resection giving Grand piano sign.
- Tibial preparation
  - intramedullary / extra medullary alignment referencing.
  - dislocate tibia and externally rotate
  - Proximal cut perpendicular to mechanical axis
  - Tibial slope 5 to 7 degree
  - In CR recreate natural tibial slope formPCL to function and to ahem a better femoral rollback.
  - Tibial cut aligned with medial 3rd of tibial tuberosity.
  - PS VS CR
  - Meta-analysis PS VS CR no difference in flexion, ROM and complication.
Soft tissue balancing
- Technique
  - measured resection
  - Gap balancing
patella resurfacing
- Restore patella height and optimise extensor mechanism
- Non resurfaced VS resurfaced patella no difference