Jan 29, 2015
Micro Holes, Macro Results

In the past, suffering a chondral defect often meant an end to an athlete’s career. Today, exciting advances in microfracture surgery and rehab are allowing players to come back more explosive than ever.

By R.J. Anderson

R.J. Anderson is an Assistant Editor at Training & Conditioning. He can be reached at: [email protected].

When Phoenix Suns center Amare Stoudemire awoke from anesthesia on Oct. 11, 2005, he heard the word every basketball player dreads: microfracture. Complaining of intermittent knee pain that had been lingering for weeks, Stoudemire had elected to have a diagnostic arthroscopy. He knew ahead of time that the surgeon might find a significant cartilage defect and immediately perform a microfracture procedure. But he was hoping that wouldn’t be the case.

Fear of microfracture surgery is very real. Stoudemire undoubtedly recalled the returns of high-profile NBA players Chris Webber, Allan Houston, and Anfernee Hardaway–none of whom recaptured their pre-injury greatness after having the surgery.

But thanks to the skills of a premier orthopedic surgeon utilizing the latest microfracture technique, and a carefully designed, full-body rehab program steeped in corrective exercise, Stoudemire did regain his form, earning first-team All-NBA honors at the end of the 2007 season. He also gave athletes with cartilage damage new hope, including 2007 NBA number-one draft pick Greg Oden, who underwent the procedure in August.

On the Table

Microfracture surgery is performed to restore damaged articular cartilage, sometimes called a chondral defect. Such defects can occur any place cartilage exists, and in the knee they are most commonly found at the tibial condyles, the femoral condyles, or the backside of the patella where it contacts the tibia and femur in the medial compartment. How these injuries develop is not always clear, but they seem to occur either through a twist of a bent knee, a direct blow, or after a series of minor injuries.

The goal of the surgery is to bring blood and bone marrow to the defective area through a blood clot that contains tissue-building stem cells. The term “microfracture” refers to the tiny holes a surgeon makes in the patient’s bone that allow the blood and stem cell-containing bone marrow to seep into the area. With proper rehab, the tissue is trained to become healthy cartilage as it heals over the defective area.

While this surgery has been around for nearly 30 years, both the procedure and the rehab approach have greatly improved over the last decade. Before microfracture surgery was considered a viable option for elite injured athletes, those with chondral defects simply lived with the pain, usually experiencing a decline in performance and a shortened playing career.

A key part of any microfracture surgery is debriding the calcified “old” cartilage and creating a bed in which the new cartilage can form. Richard Steadman, MD, Orthopedic Surgeon and co-founder of the Steadman Hawkins Clinic in Vail, Colo., who is credited with pioneering knee microfracture surgery in the late 1980s and remains one its most successful practitioners, says completely removing the deepest layer of calcified cartilage is a surgical advance developed in the last five years or so.

“If the area where you’re trying to build new cartilage still has a layer of the old cartilage, it resists allowing the new cartilage to form,” says Steadman. “If you don’t remove that layer and create a bed on the bone with edges of stable cartilage surrounding it, we’ve found the chances of success are quite a bit lower. The healthy rim of cartilage around the bed decreases the amount of pressure shouldered by the new tissue and provides a cushion during the healing process.”

After a bed to house the new cartilage is created, a curved surgical awl is used to make microscopic punctures spaced about three or four millimeters apart at the ends of the bone. Steadman says using the awl allows surgeons to penetrate the subchondral bone while leaving the subchondral plate intact. “The subchondral plate is important for the functioning of articular cartilage, so most cartilage experts feel it is better to leave that plate in place,” he says.

Over time, Steadman says the procedure has evolved to now incorporate shallower holes–about three millimeters deep. “We’ve learned that you don’t have to go very deep, just enough to access the bone marrow,” he says. “If you go farther than that, the surgery is less likely to be successful.”

After the blood and marrow accumulate in the freshly scraped bed on the bone, the stem cells begin their healing magic, forming a new layer of tissue. This tissue consists mostly of type II collagen, which is the major protein found in cartilage and serves as the “glue” that holds the cartilage together while helping to provide elasticity within the joints. Type II collagen also contains mucopolysaccharides, which help the cartilage to heal itself.

“Articular cartilage is type II collagen,” Steadman says. “In a study we did on horses, we were able to take samples of regenerated cartilage and analyze them in several cases, and it turns out 70 percent of the new cartilage is made up of type II collagen–meaning it’s very similar to the original tissue.”

The molecular makeup of the regenerated cartilage isn’t the only discovery Steadman credits to the horse study, which he conducted in collaboration with the Colorado State University College of Veterinary Medicine and Biomedical Sciences. He says a number of surgical advances were prompted by his equine work, including the timeframe of his rehab protocol–especially the protective weight bearing phase. Most protocols call for the athlete to spend the first six to eight weeks post surgery in a protective weight bearing environment, and Steadman recommends a full eight weeks.

“We looked at horses’ cartilage after two weeks, four weeks, six weeks, and eight weeks, and found that eight weeks is when it looked mature enough to take the pressure of full weight bearing,” he says.

Another key part of the rehab protocol is to begin continual motion immediately. “Basically, our theory is that the new tissue needs a mechanical message to tell it what it should become,” explains Steadman. “With cartilage, you’d like a message that tells the new tissue it needs to be smooth and to fill in the defect. You want motion to convince these cells that they want to become cartilage, not bone or muscle or anything else. The constant motion and protective weight bearing are factors that send the right message to those cells.”

To provide the motion, immediately after surgery, patients can use a continuous passive motion (CPM) machine. “After about two to four weeks, if the patient is doing well, I’ll allow them to spin on a stationary bike, which gives them that smooth exercise,” Steadman says. “Then they can begin deep water running in which they don’t touch the bottom. Those types of movements stimulate the tissue to form a better quality cartilage.”

Ready for Rehab

In Stoudemire’s case, the arthroscopy revealed a fairly small lesion–a one-centimeter by one-centimeter chondral defect. Still, Thomas Carter, MD, an orthopedic surgeon at The Orthopedic Clinic Association in Phoenix and Team Physician for the Suns, decided to go ahead with the microfracture surgery, fearing that if left alone, the damaged cartilage would flake off and expand the lesion. During the 30-minute procedure, Carter scraped the damaged tissue in the femoral condyle region of Stoudemire’s knee, then made five microfracture holes to trigger the formation of the replacement cartilage.

The surgery deemed a success, Stoudemire readied himself for the long, arduous journey back. For the first week, he was at home with his knee completely unweighted, undergoing ice compression treatments and hooked up to a CPM machine.

Meanwhile, Suns Head Athletic Trainer Aaron Nelson, ATC, NASM-PES, CSCS, was hard at work, drawing up a blueprint for Stoudemire’s rehab. While he had assisted with other microfracture rehabs, this would be Nelson’s first experience with an athlete fresh off of the surgery.

“I started my research by finding out everything I could on other athlete rehabs, and I looked at different surgeons’ protocols,” Nelson says. “Then, Dr. Carter and I had a long conversation about his expectations and what he thought would and should happen throughout the process.”

Nelson also consulted with Micheal Clark, DPT, MS, NASM-PES, President and Physical Therapist at the National Academy of Sports Medicine, to design a comprehensive science-based rehab program. “We took what everybody else had done in the past and looked at what would be best for Amare, then basically laid out a plan and moved forward,” Nelson says.

Determining what would be “best for Amare” began before the surgery, when Nelson evaluated Stoudemire from head to toe. “We did a Kinetic Chain Assessment (KCA) of his overall body strength, flexibility, and mechanics prior to the surgery,” says Nelson. “We’re not positive what caused the cartilage damage, but our plan was to identify and eliminate any type of dysfunction that could cause a problem down the road or that might have contributed to his pre-surgery problems. At the same time we were rehabbing the knee after microfracture surgery, we wanted to address those other issues.”

There are a few schools of thought on what triggers a chondral defect, and it’s fairly certain there is no single answer. For example, some experts feel that a bone bruise can cause swelling and lead to microtrauma that worsens over time. There also seem to be some acute cases when an impact instantly tears the cartilage.

Regardless, Clark, who provides continuing education programs to the NBA Athletic Training Association, says his 10-plus years working with athletes who have had microfracture surgery leads him to believe there are usually movement impairments that contribute to the injury. (See “Smooth Moves” below.) He says identifying and correcting those deficiencies is important to both preventing future injury and compensating for complications during and after rehab.

“We try to identify these movement impairments and typically find they are a result of certain muscles that are too short and too tight,” says Clark. “This leads to movement impairment and muscle imbalances that can create trauma at the knee.”

When planning the rehab, a major goal was to have Stoudemire’s deficiencies corrected during the protective weight bearing phase. “That was a perfect time for us to hammer out those deficiencies and create activation of those muscles and joints that had been shut off,” Clark explains. “That way, when he started to fully bear weight again, he would have symmetrical joint motion and symmetrical muscle activation, which would take as much stress as possible off his knee during rehab.” Making Corrections

For the pre-surgery KCA, Stoudemire performed several exercises and movements. Most telling were his compensations during an overhead squat. “If the athlete has proper range of motion in the ankles, knees, and hips, and proper muscle activation in the lower leg, hip, stomach, and low back, they’ll be able to squat down while keeping their feet straight with their knees lined up over their second and third toe and their trunk upright,” Clark says.

“But what we see with a lot of athletes is that when they squat down, they either pronate, their feet turn out and their knees cave in, or their spine moves into flexion,” he continues. “Those are movement impairments and potential predictive factors of overuse injury at the knee. They can lead to serious articular cartilage damage, which could then necessitate microfracture surgery.”

One particular impairment Nelson and Clark discovered in Stoudemire was weakness in his upper gluteus maximus–a deficiency that has far-reaching implications. “When you’re running, at the point when one foot is forward and one foot is back, your opposite arm and lat work together to create that motion,” explains Clark. “If you have weakness in one of your glutes, the opposite lat has to work too hard and that can make it short and tight. If your left glute is weak, your right lat can be tight, and a tight right lat can rotate the right side of your pelvis forward, creating a pelvic imbalance that can cause a variety of complications, including additional stress on the knee.”

During the eight weeks of protective weight bearing work, Stoudemire worked with Nelson and Clark for three hours a day, five days a week. He performed foam rolling, stretching, and isolated, non-weight bearing corrective exercise, including plenty of work to strengthen his intrinsic core muscles. Many of the corrective exercises focused on strengthening his upper gluteus maximus.

After four weeks, the rehab team had Stoudemire doing single-leg lower-body work with his non-injured leg and workouts on a stationary bike. Increasing the weight he was able to bear was largely facilitated through hydrotherapy. Once his incisions had healed 10 days post surgery, Nelson had Stoudemire in the water every day possible.

“As he progressed and regained most of his range of motion, after about 10 to 12 weeks, we were able to do more partial weightbearing stuff with him–then he was only in the pool two to three times a week,” says Nelson, adding that Stoudemire still does hydrotherapy as preventative maintenance.

From there, Nelson and Clark evaluated Stoudemire’s swelling, quadriceps girth, and range of motion in the knee before progressing. “Every day we measured swelling of the knee joint–which should decrease every day post-surgery. If it went up, we backed the rehab off instantly,” Clark says. “We also looked for increased range of motion every day. If for some reason he lost motion, we backed off. His quad girth also had to increase in order for us to move forward.”

Although the rehab was long, Nelson says everything went smoothly. “It’s tenuous and redundant, which is challenging mentally–you do a lot of the same stuff over the different phases,” he says. “But it was my job to reassure Amare and help him fight through the boredom. You have to make the athlete realize that everything is a stepping stone and you’re going one block at a time as you build them up.”

A Success

Many variables determine whether or not an athlete successfully returns from microfracture surgery, including the size and location of the lesion, and the athlete’s medical history. But Nelson focuses on three controllable factors.

“One, you’ve got to have an experienced surgeon who does a great job,” he says. “Two, you need the athlete to be motivated and compliant. And three, the athlete has to do everything the rehab team asks.”

In Stoudemire’s case, all three were satisfied. He emerged from his rehab more balanced, more flexible, and with greater intrinsic core strength. A strong, healthy knee and a return to explosiveness were the end products of his hard work.

Though a success, Stoudemire’s rehab was not without hiccups. He missed nearly one full season of play, and wasn’t back to full strength until midway through the 2006-07 campaign. In the time since the microfracture surgery, he has had two additional arthroscopies–the latest one prior to this season–which his rehab team says may or may not be related to the chondral defect. “They were basic scopes that could have happened regardless of the prior injury,” says Clark. “We can’t make any cause-and-effect conclusions about those procedures.”

So far during the 2007-08 season, Stoudemire’s knee has been strong. “Knock on wood, there has never been a swelling issue with his knee,” says Nelson. “He gets a little stiff from time to time, but nothing significant. It’s normal wear and tear that even non-surgically repaired knees have.”

Since Stoudemire’s successful return to the court, Nelson and Clark have fielded numerous requests from colleagues looking to obtain similar results with athletes who have chondral defects. “When we talk to other people conducting microfracture rehabs, we don’t really go into detail about the actual knee rehab because everybody is doing a good job there,” says Nelson. “We focus on making sure they look at the entire body–trying to identify any imbalances that may overstress the knee. We also tell them to focus on core, balance, and functional training–not just isolated knee rehab.”

“From my perspective, the take-home message is that it’s not a mysterious injury–we just have to look at what deficiencies are causing it,” says Clark. “Typically, muscles, ligaments, and cartilage from each leg should be the same strength, and if a deficiency exists, it can be the proverbial straw that breaks the camel’s back.”

Sidebar: Smooth Moves

When Micheal Clark, DPT, MS, NASM-PES, President and Physical Therapist at the National Academy of Sports Medicine, evaluates athletes who are at risk for articular cartilage damage in the knee, these are the most common compensation patterns he sees, which tend to occur when an athlete cuts, lands, or decelerates from a jump:

Tibial external rotation: The athlete’s foot turns to the outside during landing and then caves inward. “That causes a shear force of the femur moving across the tibia and creates repetitive microtrauma of the articular cartilage,” says Clark.

Trunk flexing forward: When an athlete lands from a jump, instead of keeping their trunk upright and parallel to their lower leg, their chest collapses toward their knees. “When the athlete’s trunk flexes forward, they lengthen the gluteus maximus, which forces the hamstring to eccentrically control the lower leg and the loading of hip flexion,” says Clark. “And if their foot is already turned out into external rotation, they’re facilitating the lateral hamstring, or biceps femoris, which causes stress at the knee.”

Limited dorsiflexion in an opposite ankle: “Let’s say it’s the right knee that’s bothering an athlete,” Clark says. “In many cases, we see that the left ankle is restricted. If an athlete jumps for a rebound and lands, the dorsiflexion when landing from a jump needs to be at about 15 degrees. But many NBA players we see only have five degrees of dorsiflexion.

“If their ankles don’t bend, their knees must deal with the force,” he continues. “And the next joints up from the knees are the hips, then the spine. When they land, they have to shift the weight over to their right and their right knee takes most of the eccentric load, and you get shear, compressive force on the joint that creates trauma.”

Limited motion in the big toe: Clark says his assessments show that a lot of athletes have restrictions in one or both big toes. “If you’re loading eccentrically to jump, you have to get motion at your big toe,” he says. “If a restriction exists and the big toe can’t bend backward, the foot has to flatten out to compensate. When that happens, it lengthens the muscles on the inside of the calf, and then the muscles on the outside of the calf have to work too hard.

“If there is an imbalance where one side is pulling harder than the other, the joint will move in the direction of the muscle that’s pulling harder,” Clark adds. “That turns the foot to the inside, and if you jump, land, cut, or do anything with your knees in that position, the femur has to slide across, which creates massive stress.”

When rehabbing athletes from a microfracture procedure, Clark recommends athletic trainers and physical therapists go through a proper joint assessment, starting with the big toe and working their way through the ankle and hips, and also testing hamstring length, hip internal rotation, and hip extension. “Those are the primary areas that have to be within a certain range of motion,” Clark says. “If you don’t restore those joint motions when the athlete is rehabbing from microfracture, and they begin bearing weight, they will put increased stress on the microfracture in an early stage, which then creates swelling in the joint and doesn’t allow the cartilage to heal very well. That’s a big problem we’ve seen in a lot of the failed micros of the past.”


Great article! I am a student in a physical therapy assistant program andI will be using this as a resource on my presentation of microfracture and use Amare as a case study. Do you know if there are any more details as to the specific rehab exercises that were performed? Thanks!

– Gary Brito

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