Microfracture Technique for Knee Injuries

- Discussion: - see management of osteochondral injuries
       Microfracture is a knee surgery that involves the creation of multiple perforations (microfractures in the subchondral bone) in areas that are cartilage deficient.
       The theory behind this type of technique is that simple abrasion arthroplasty may not allow a sustained reparative response (no more than 2 weeks of
       healing) where as the micro-fracture technique (which penetrates the subchondral bone) allows a better and more sustained healing process.
       Microfracture is often chosen as the benchmark for which to compare to other cartilage repair procedures.
 
- Role in Degenerative Arthritis in the Knee: - see osteoarthritis and arthroscopy of the degenerative knee 
        - references:
                  - The Treatment of Articular Cartilage. Defects Using the Microfracture Technique 
                  - Orthopaedic Surgeon Performs Innovative Microfracture Procedure On Arthritic Knees Avoiding Knee Replacement Surgery 
                  - DEBRIDEMENT, ABRASION and MICROFRACTURE for OSTEOARTHRITIS of the KNEE   
                  - Microfracture Surgery Recovery: Slow Down for Best Results
                  - Steadman Hawkins Research Foundation 
                  - Microfracture Surgery for Cartilage Regeneration in Degenerative Arthritis of the Knee. 
                  - Knee Microfracture Surgery: New York Times Health Guide
                  - Knee microfracture surgery
                  - What is New in the Treatment of Focal Chondral Injuries of the Knee?
                  - Microfracture success depends not only on the operation but rehabilitation as well
                  - Treatment of Osteoarthritis of the Knee with Microfracture and Rehabilitation
                  - Cartilage healing after microfracture in osteoarthritic knees. 
                  - Patient satisfaction and outcome after microfracture of the degenerative knee.
                  - Articular cartilage regeneration with microfracture and hyaluronic acid. 
                  - Early results of medial opening wedge osteotomy in varus gonarthrosis
                  - Benefit of microfracture, implant for cartilage defects seen in early studies

- Surgical Technique: 
        - an arthroscopic awl is used to make multiple perforations (microfractures) in the subchondral bone; 
        - removal of the calcified cartilage layer:
                 - curet is then used to remove the calcified cartilage layer from the base of the lesion; (see articular cartilage)
                 - calcified cartilage layer: (see articular cartilage defects)
                            - thin layer between the deep zone of the cartilage and the subchondral bone
                            - can increase in thickness with age
                            - removal of the calcified cartilage may improve the bonding of the repair tissue to the subchondral bone after microfracture;
                            - references:
                                     - Arthroscopic microfracture technique augments healing of chondral defects in radial carpal bone and medial fem condyle of horses.
 
                 - bone is perforated every 4-5 mm to a depth of 3-4 mm 
                 - classic teaching is to use an awl, but recent evidence supports drilling;
                            - ref: Drilling and microfracture lead to different bone structure and necrosis during bone-marrow stimulation for cartilage repair.
                 - theory behind this type of technique is that simple abrasion arthroplasty may not allow a sustained reparative response (no more than 2 weeks of healing)
                            where as the micro-fracture technique (which penetrates the subchondral bone) allows a better and more sustained healing process; 
                 - patients are kept non wt bearing for 6-8 weeks.
                 - references:
                          - The surgical treatment of knee injuries in skiers.  Steadmand JR and Strereet WI.  Med Sci Sports Exerc. Vol 27 1995. p 328. 
                          - Treatment of articular cartilage defects in athletes: An analysis of functional outcome and lesion appearance. Orthopedics July 1998. Vol 21. 1998. p 761.
                          - Early events in cartilage repair after subchondral bone microfracture.
                          - Chondral Defect Repair After the Microfracture Procedure.  A Nonhuman Primate Model. 
                          - The Microfracture Technique for the Treatment of Articular Cartilage Lesions in the Knee. 
                          - A Randomized Trial Comparing Autologous Chondrocyte Implantation with Microfracture. Findings at Five Years
                          - Effects of calcified cartilage on healing of chondral defects treated with microfracture in horses.
                          - Early events in cartilage repair after subchondral bone microfracture.
                          - Healing of canine articular cartilage defects treated with microfracture, a type-II collagen matrix, or cultured autologous chondrocytes.