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MICROFRACTURE OF THE KNEE

Method
Arthroscopic microfracture (a bone-marrow-stimulating technique)
Duration
30 to 60 minutes
Recovery time
6 to 12 weeks

How does microfracture work?

Microfracture is an arthroscopic procedure for treating well-defined cartilage defects in the knee joint. The subchondral bone plate is deliberately broken through in order to release stem cells and growth factors from the bone marrow. The aim is to form a replacement cartilage (fibrocartilage) that fills the defect and so improves the function of the joint.

Once the cartilage defect has been visualised arthroscopically, the damaged area of cartilage is cleanly removed with a burr and the edge of the defect stabilised. Several small holes are then punched into the bone plate beneath the defect with a fine, pointed instrument (an awl or a microfracture pick). Blood and bone marrow containing stem cells emerge from these micro-fractures.

These stem cells settle in the defect and differentiate into fibrocartilage-like tissue. The method is particularly suited to smaller, well-defined cartilage defects in young, active patients without advanced osteoarthritis. Aftercare is decisive for success, because the newly formed tissue needs time to mature.

Rehabilitation after microfracture

After a microfracture a consistent period of unloading is necessary so that the replacement cartilage can form and heal in. Rehabilitation is divided into several phases:

Phase I (0-6 weeks): unloading and passive mobilisation
  • Unloading on forearm crutches (as a rule for 6 weeks)
  • Movement splint (CPM) for passive mobilisation
  • Cooling, lymphatic drainage and anti-inflammatory treatment
  • Avoiding everyday activities that load the joint (squatting, crouching)
Phase II (6-12 weeks): building up load and function
  • Gradual increase in load up to full weight-bearing
  • Physiotherapy to activate the muscles and improve movement
  • Balance and co-ordination training
  • Exercise-bike training with little resistance
Phase III (from week 12): load tolerance and return to sport
  • Strengthening the whole of the leg muscles
  • Sport-specific build-up training from month 4-6
  • Return-to-sport tests before loading is cleared
  • Avoiding overloading in the long term (for instance jogging on hard ground)