Matt Kemp Out with an Osteochondral Lesion
Matt Kemp, who is an outfielder for the Los Angeles Dodgers, will be unable to help the Dodgers in the post season this year due to an MRI showing swelling in one of the major weightbearing bones in Matt Kemp’s ankle, the talus. Kemp initially injured his ankle in a play at the plate against the Washington Nationals on July 21. After missing 52 games on the disabled list, he returned to play on September 16th but was held out of Saturday’s game due to soreness in his ankle. This prompted an MRI that revealed swelling in the talus (osteochondral lesion), taking Kemp out of the lineup in the post season.
What does swelling in the ankle (talus) mean?
On an MRI after an ankle sprain injury, swelling in the talus typically will mean that there is some cartilage damage in the bone, called an osteochondral lesion. When an ankle is sprained, a number of different structures can be injured. In addition to the ligaments and tendons around the ankle being torn, occasionally a small piece of cartilage can chip off of the talus bone. This cartilage damage is usually not readily seen on x-rays, but will often show up on MRI as bone swelling. A CT scan may be useful in determining the size of the osteochondral lesion.
What is the treatment of an osteochondral lesion?
Treatment of an osteochondral lesion depends on the location and severity of the lesion. Lesions on the inside, or medial aspect, of the talus are usually deeper and more stable. Lesions on the outside, or lateral aspect, of the talus are usually shallower and wafer shaped – making them less stable. Osteochondral lesions can be classified as compression or bruising of the bone (stage I), partially detached (stage II), completely detached but non-displaced (stage III), or completely detached and displaced in the ankle joint (stage IV). Stage I, II, and lateral stage III lesions are best treated conservatively with a period of immobilization that includes a non-weightbearing below knee cast for six weeks. If pain persists after this period of immobilization, surgery may be indicated. Medial stage III and stage IV lesions are best treated with surgery.
What are the surgical options for an osteochondral lesion?
There are a number of procedures that can be done depending on the size and depth of the osteochondral lesion. Before surgery, the size and depth of the lesion should be determined with a CT scan to help with planning the appropriate procedure.
Cartilage in general has a poor blood supply and it has poor healing potential. Microfracture surgery involves drilling holes into the lesion to stimulate blood flow in the area and promote the formation of fibrocartilage. This procedure is fairly minimally invasive as it is often done through a scope. This procedure has good outcomes for smaller lesions.
A cartilage graft can be placed in the area of the osteochondral defect to effectively replace damaged cartilage. This method is usually reserved for lesions of about 1 cm in diameter. In this procedure, the osteochondral lesion is punched out and replaced with a cartilage graft of identical size from a donor. For the best results, a graft is taken from the similar bone in which the osteochondral defect is present as to recreate the anatomic contour of the joint as best as possible. This is best done with a cadaver bone that matches the affected ankle. Cadaver bones should be used within 14 days of it being harvested and should be fresh, not frozen. Frozen grafts will deteriorate cartilage cells and reduce the ability of the graft to successfully incorporate into the host.
Mesenchymal stem cells make up about 2-3 % of all blood cells in bone marrow and they have the ability to differentiate into different types of cell types if placed in the right environment. They also have the ability to stimulate new blood vessel growth, which is important in developing avascular tissue such as cartilage. Stem cells can be separated from bone marrow that is harvested from the body and either injected into the ankle joint or placed over the osteochondral lesion itself in a gel form with a scaffold graft. The stem cells will then differentiate into cartilage due to the growth factors and signals that are present in the environment in which they were placed.
What should Matt Kemp do?
The current treatment plan for Matt Kemp is immobilization in a non-weightbearing cast. This likely means that the lesion is either a stage I, II or lateral stage III lesion and likely to heal with conservative treatment. It is very important to rest this injury because the talus bone does not have a great blood supply. Due to this, any additional pressure that is placed on the ankle may cause the lesion to get bigger and ultimately cause arthritic changes in the future. A CT scan would be useful in evaluating any cartilage or bone defect that may be present in the ankle. Should he continue to have pain after this period of immobilization, surgery may be indicated. After immobilization, a period of rehab is needed. Range of motion and strengthening exercises are done to help strengthen the ankle. Assuming conservative treatment works, Matt Kemp should be back for spring training in 2014 to help the Dodgers reach the post season again.
Dr. Baravarian been involved in athletics his entire life and played competitive tennis in high school and college. He has an interest in sports medicine, arthritis therapy and trauma/reconstructive surgery of the foot and ankle. He servers as a consultant to the ATP (Association of Tennis Professionals) tour, multiple running organizations and several shoe manufacturers. He is also fluent in five languages (English, French, Spanish, Farsi and Hebrew),
Podiatrist Dr. Bob Baravarian is available for consultation at the Santa Monica, Sherman Oaks and UCLA Westwood offices.
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