Microfracture Knee Surgery: Recovery and Clinical Outcomes

It is essential to stick religiously to the prescribed rehabilitation plan for the procedure to be successful. The main goal of the rehabilitation program is to provide motion without shearing or applying high-loading stress to the treated chondral defect. (1, 7)
Patients are kept at protected weight bearing for 6 to 8 weeks. This is longer than the period for debridement and drilling procedures. If the defect is in a non-wieght-bearing region, weight bearing can begin closer to 6 weeks post surgery depending on the size of the effected area. (7, 13)
Patients are sent home with a continuous passive motion machine for 8 weeks to limit atrophy. The machine works the motion of the knee from 10 degrees to 90 degrees for at least 8 hours a day, usually at night. The machine is set at 1 cycle per minute to exercise the largest range of motion that the patient finds comfortable. Animal studies have shown that continuous passive motion advances the formation of fibrocartilaginous repair tissue. If this machine is not available, exercises are substituted in its stead. The patient is required to perform full knee range of motion exercises such as cycling their knee over the edge of a table 1,500 times per day. Other exercises include three sets of 1,500 active leg flexion/extension exercises each day. (1, 7)
Postoperative weight-bearing status is affected by the location of the lesion. Patients with femoral condyle or tibial plateau lesions are to remain non weight bearing for 8 weeks. Patellar and trochlear groove lesions may be weight bearing as tolerated in a hinged brace with a 20 degree flexion stop while walking for 8 weeks. If the injury was in the medial or lateral compartment, the patient is allowed 15% weight bearing, with similar use of the continuous passive motion machine to that in patellofemoral lesions. (1, 7)
Patients remain in a brace for the entire recovery period other than when they are not weight bearing and go into the continuous passive motion machine. (7)
At 2 weeks, patients begin deep water running and stationary cycling. (1)
After the extensive 6 to 8 week period on the continuous passive motion machine and protected weight bearing, the patient begins active range of motion exercises and moves to full-weight bearing. (7)
At 12 to 16 weeks, patients can begin jogging. (1)
Cutting, twisting, or jumping activities are prohibited until at least 4 months post operation. (1, 7)
After recovery and rehabilitation the healing may be incomplete. If this is the case, a second microfracture to the exposed area can be performed. (7)

Procedure	Range of Motion Considerations	Consideration for Enhancing Muscle Function	Weight-Bearing Consideration
Arthroscopic Lavage and Debridement	Passive and unloaded active range of motion exercises with no restrictions on range of motion	Isometric and limited arc resisted open and closed chain exercises as tolerated	Partial weight bearing or weight bearing as tolerated gait; Discontinue assistive devices when: Full passive knee extension, at least 100 degrees of flexion, no knee extensor lag, able to ambulate without symptoms or gait deviations
Abrasion Arthroplasty, Subchondral drilling and Microfracture procedures	Unloaded passive range of motion exercises in range as tolerated	Isometric exercises at angles which do not engage the articular cartilage lesion; Limited arc resisted open and closed chain exercises after 4 to 6 weeks	Non-weight bearing or touch down gait for 6 weeks; Progress to weight bearing at tolerated gait after 6 weeks; Discontinue assistive devices when conditions for arthroscopic lavage and debridement met
Osteochondral grafts	Unloaded passive range of motion exercises in range as tolerated; May need to restrict motion dependent on fixation of graft	Isometric exercises at angles which do not engage the articular cartilage lesion Limited arc resisted open and closed chain exercises after 4 to 6 weeks	Non-weight bearing or touch down gait for 6 weeks; Progress to weight bearing at tolerated gait after 6 weeks; Discontinue assistive devices when conditions for arthroscopic lavage and debridement met
Osteotomy	Unloaded passive range of motion exercise in range as tolerated	Isometric quadriceps exercises with no loading across osteotomy site for 4-6 weeks (i.e., quad sets and unloaded straight leg raises until the osteotomy site has healed; Limited arc resisted open and closed chain exercises after 4 to 6 weeks	Partial weight bearing or weight bearing as tolerated with rehabilitation brace locked in full extension for 4-6 weeks; Discontinue assistive devices when conditions for arthroscopic lavage and debridement met

Table: Summary of rehabilitation considerations for surgical procedures for articular cartilage lesions of the knee
Adapted from James Irrgang, (11)

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