Knee - Osteotomies
60% of the load of the body weight passes through the medial compartment of the knee
Loads up to 4 times body weight are produced on climbing stairs
Osteotomy redistributes the force
Valgus osteotomy most commonly performed (varus knee) and is indicated in patients that have uni compartmental disease, are less than 60 - 70 years old, are of optimal weight, have an active occupation or lifestyle which they want to maintain and have a good range of motion
NB: ROM is not likely to improve with an osteotomy
INDICATIONS
- Age: physiologic age < 60 yrs in an athlete, laborer, or anyone who needs to knee down such as for gardening (TKR will generally not allow the patient to kneel)
- Weight: > 80 kg are at increased risk for component failure;
- Angular Deformity:
- > 15 deg of fixed varus deformity (often patients will have varus laxity)
- < 15 degrees flexion contracture
- > 90 degrees flexion
- Radiologically intact lateral (or medial) and patellofemoral compartments
CONTRAINDICATIONS:
- Tibial Subluxation > 1 cm
- RA & inflammatory arthritis
- ACL tear
- osteochondral injuries with involvement of more than 1/3 the condylar surface or OCD lesion of more than 5 mm deep
CLINICAL
- Observe patient walk (look for varus thrust)
- Stability
- Q Angle
- Compensatory arc of motion - to correct a valgus knee deformity - for a 20-degree varus osteotomy, 20 deg of abduction at the hip is required so pt does not end up with an adduction deformity
- Examine the foot and ankle to rule out fixed varus deformities which may worsen medial compartment loading
- Leg length discrepancy Coventry closing wedge osteotomy might be indicated, where as, if the arthritic side is shorter (than the other leg), then consider opening wedge osteotomy
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