Force applied to a less stiff knee is more likely to result in ACL tears.In addition, the quadriceps femoris muscle is an antagonist to the ACL. According to a study done on female athletes at the University of Michigan, 31% of female athletes recruited the quadriceps femoris muscle first as compared to 17% in males. Because of the elevated contraction of the quadriceps femoris muscle during physical activity, an increased strain is placed onto the ACL due to the "tibial translation anteriorly". Pathophysiology
The knee joint is formed by three bones: the femur (thighbone), the tibia (shinbone), and the patella (kneecap). These bones are held together by ligaments, which are strong bands of tissue that keep the joint stable while an individual is walking, running, jumping, etc. There are two types of ligaments in the knee: the collateral ligaments and the cruciate ligaments.The collateral ligaments include the medial collateral ligament (along the inside of the knee) and the lateral or fibular collateral ligament (along the outside of the knee). These two ligaments function to limit sideways movement of the knee.The cruciate ligaments form an "X" inside the knee joint with the anterior cruciate ligament running from the front of the tibia to the back of the femur, and the posterior cruciate ligament running from the back of the tibia to the front of the femur.
Micrognathism is a condition where the jaw is undersized. It is also sometimes called mandibular hypoplasia. It is common in infants, but is usually self-corrected during growth, due to the jaws increasing in size. It may be a cause of abnormal tooth alignment and in severe cases can hamper feeding. It can also, both in adults and children, make intubation difficult, either during anesthesia or in emergency situations. Causes
While not always pathological, it can present as a birth defect in multiple syndromes including:

Catel–Manzke syndrome
Bloom syndrome
Coffin–Lowry syndrome
Congenital rubella syndrome
Cri du chat syndrome
DiGeorge syndrome
Ehlers–Danlos syndrome
Fetal alcohol syndrome
Hallermann–Streiff syndrome
Hemifacial microsomia (as part of Goldenhar syndrome)
Incontinentia pigmenti
Juvenile idiopathic arthritis
Marfan syndrome
Möbius syndrome
Noonan syndrome
Pierre Robin syndrome
Prader–Willi syndrome
Progeria
Silver–Russell syndrome
Seckel syndrome
Smith–Lemli–Opitz syndrome
Stickler syndrome
Treacher Collins syndrome
Trisomy 13 (Patau syndrome)
Trisomy 18 (Edwards syndrome)
Trisomy 21 (Down syndrome)
Wolf–Hirschhorn syndrome
X0 syndrome (Turner syndrome)

Diagnosis
It can be detected by the naked eye as well as dental or skull X-Ray testing. Treatments
Micrognathia can be treated by surgery, orthodontic braces, and modified eating methods. Early detection of the problem and monitoring as the problems grows can help understand it better and find the most effective treatment procedure. See also
Human mandible
Macrognathism
Retrognathism

References
External links

"Micrognathia". Medline Plus. 12 May 2009. Retrieved 21 May 2011.