While the exact injury or injuries that have befallen the All-Star still remain conjecture, we can still take a closer look at the processes involved and the anatomy of the knee and establish a baseline of knowledge that can provide a clearer picture of what the near future might possibly hold for the third baseman.
Judging from the video of the injury, Machado's foot caught the corner of first base awkwardly, forcing his knee to buckle inward and creating excessive valgus force and rotation upon the knee joint while his foot remained planted:
|A head on look at the bones of the knee joint and valgus rotation. Courtesy of annals.org|
Upon sustaining the injury, Machado was then questioned by the medical staff; questions in this type of acute setting usually revolve around what the mechanism of injury was, whether a 'pop' was heard or felt, and where the pain arises from primarily. At this point, a quick examination, limited to palpating the knee for areas of tenderness or crunching sensation - called crepitation - and an assessment of ligament health and stability are performed in order to rule out more severe injuries, such as dislocations or fractures. From there, the limb is immobilized.
Diagnostic imaging, especially x-ray, is then performed to provide additional information such as joint alignment, fracture, or bone chips. MRI studies can also be performed once immediate swelling has subsided, allowing an exceptionally accurate picture of the disease and injury processes at play. MRI images are especially helpful in confirming injuries in ligaments and cartilage.
With respect to the anatomy of the knee and knowing Machado's knee buckled medially (inward), what could possibly be at risk?
|Image courtesy of athleticadvisor.com|
The mensicus is the c-shaped, cartilagenous part of the knee that provides cushioning for the tibia and femur bones, while also assisting in the even transmission of weight across the femur - tibia interface. It also provides some nutritional and lubrication support of the knee. It is often torn when twisted or turning quickly, with the knee bent and the lower leg firmly planted. These are some of the more common lower body athletic injuries seen and are often accompanied by a tear of the anterior cruciate ligament.
ANTERIOR CRUCIATE LIGAMENT
The anterior cruciate ligament (ACL) is primarily responsible for keeping the femur and tibia bound together, preventing anterior translation of the tibia. It also assists in preventing significant varus or vagus stress of the knee; in simpler terms, the ACL prevents too much knock knee or bow legging stresses put on the knee and is one the knee's primary stabilizers. While ACL injury isn't as seen as frequently in baseball as compared to other sports, such as football, it does still occur, particularly when the mechanism of injury arises from a quick turn, sudden stop, or misstep.
MEDIAL COLLATERAL LIGAMENT
The medial collateral ligament (MCL) is the most commonly injured knee ligament, typically in the form of a sprain. It is the primary stabilizer against valgus (inward) stresses of the knee. It is unique in it having two components - static and dynamic. The static component is made up of the superficial and deep MCL and the posterior oblique ligament, while the dynamic portion of the MCL complex is comprised of aspects of the semimembranosus and vastus medialis muscles of the hamstring and quadriceps muscle groups, respectively.
While there are a number of other features of this region of the knee, the ones discussed here are the major players and the ones at greatest risk for injury during baseball competition. It will still be a few more days before the extent and complexity of Machado's injury will be known, but the potential for one or many of the anatomical features of the medial aspect of the knee discussed here to have been implicated in his injury is high. Once a confirmed diagnosis is provided, a more concise discussion of not only the anatomy at risk but also treatment and rehabilitation plans and timelines can be divulged and discussed.