Types of knee arthroplasties
- Unicompartmental Knee Arthroplasty (UCKA)
- TKA
- LPS-Flex Fixed Bearing Knee (Hi-Flex TKA)
- LPS-Flex Mobile Bearing Knee (Hi-flex TKA)
What is the minimal goal for knee flexion for ADLs
120 degrees minimal
What we need for sitting, walking, and stairs
Unicompartmental Knee Arthroplasty advantages
- Replace only diseased bone — preservation of bone stock and more normal kinematics since cruciate ligs are preserved
- Decreased blood loss and extent of surgery
- “Feels” more like a normal knee
- Greater arc of motion (0-135 deg)
- Shortened hospital stay
- Normalized gait
indications for UCKA
- OA
- Single compartment disease (medial most often)
- Activity and rest pain
- > 120 degrees ROM
- No instability — ACL intact
- Usually <55 yo
- Informed patient.
Hi-Flex fixed and mobile TKAs
Designed to mechanically sustain the loads during flexion angles up to 155 deg and to accommodate patients that have the requirements, need and ability to continue their flexible lifestyle.
Considerations for Hi-Flex TKA
- Patient activity level — more active and young
- Need for high flexion — higher level activities
- Adherence to rehab
- Surgeon’s judgement that the patient will flex beyond 125 deg post op
If the patient has desire to be able to kneel, squat, and sit cross-legged what knee?
LPS-Flex Mobile Bearing Knee!!
Plus if patient is young, active, and pretty flexible beforehand
Max Protection phase post op TKA
- Control pain and swelling
- Achieve independent ambulation and transfers with AD
- Prevent early post op medical complications
- Regaining quad muscle strength and improving knee ROM
Mod Protecion phase post op TKA
- Achieve about 110 deg of knee flexion an full extension
- Regain LE strength and muscular endurance, balance, CardioPulm endurance
- Functional mobility
Min protection phase post op TKA
- Task- Specific strengthening exercises
- Proprioceptive and balance training
- Advanced functional training as well as strengths, power, balance, and endurance to return to a full level of functional activities/recreation in community
What should PTs know from surgeon
- Ligament stability
- Soft tissue status
- Extensor mechanism integrity
- Intraoperative ROM
Not much precautions for the knee otherwise
Key points in rehab
- Emphasize terminal extension ROM
— when possible, measure in prone
— Quick standing is energy efficient
— In standing, weight bearing line falls slightly anterior to axis of knee.
What happens with knee flexion contracture
- Excessive load on femoral and polyethylene components
- Increased quad force during weight bearing
- If 30 deg flexion contracture = quad demand rises to 50% of max contractile effort
- Imparied endurance
- Impaired function clinically
Etiology for TKA ROM loss
Pre-op ROM
Underlying disease like RA
Primary vs. Revision knee arthro
Post-op pain
Complex regional pain syndrome
Aseptic loosening or infection
Arthrofibrosis
Technical errors
ROM loss results in…
- Altered gait mechanics
- Quad fatigue
- Increased VO2 demand
- Hip/back discomfort
- Unhappy patient/poor outcome
Red flags for ROM loss
- No increase in extension range
- Hard end feel in flexion
- Increased co-contraction of quads and hams
What do you do if patellar instability/sublux/dislocation
Contact surgeon!!
What to do if there is not at least 90 deg knee flexion by week 3-4?
Contact surgeon!!
Returning to recreational activities
Pre-op activity level prior to TKA important.
If they were sedentary = no post op sports activity
If they were sports active in year prior = 77% able to return to sport
most important determinant of the likelihood of sports participation after TKA is pre-op participation in the sport itself
If patient wants to return to low impact sports post op what knee would you recommend
UCKA
