The knee is a commonly injured joint. Within recent years, the increase in ACL (anterior cruciate ligament) injuries has been remarkable. Trauma to this ligament within the knee can be serious, and injuries to it usually occur during athletic activity.
Why are knee injuries so common?
The knee is particularly vulnerable to injury. It is the joint between the two longest bones of the body, and the entire weight of the body is transferred to the foot through the knee. The knee is also more prone to injury because its stability decreases as it bends. The menisci and the ligaments provide less effective support to the bent knee.
What does the inside of the knee look like and where is the ACL?
The knee joint contains bones, ligaments, muscle tendons, cartilage, nerves, and blood vessels. A fibrous joint capsule made of collagen surrounds the joint and encircles the end of each bone to give the knee stability.
What are the signs and symptoms of an ACL injury?
A twist or strain has occurred which causes the following signs:
“Pop” – Many patients, but not all, will hear or feel a “pop” when the ACL tears.
Immediate onset of swelling – This is an indication that there is bleeding from the injured ligament.
Pain – Most patients experience quite a bit of pain with an ACL injury.
Instability – Patients often describe a buckling or unstable sensation in the knee.
How is an ACL injury diagnosed?
Dr. Lundy will want to know the history of the knee injury and will determine if the signs and symptoms of an ACL injury are present.
After taking a history, the orthopaedic surgeon will perform a physical examination. The doctor will perform manual tests on the knee to determine the amount of instability that exists. The Lachman Test, Anterior Drawer Test, and
Pivot Shift Test are exams the doctor may use to see how much the tibia moves in relation to the femur.
Pain, swelling, and muscle spasms in the early stages of an injury may make it difficult for the doctor to diagnose the degree of instability with manual tests. An arthrometer, a machine that measures joint looseness in the knee, may be used.
X-rays can reveal signs of bone fractures, chips, or arthritis. Since X-rays can only show bone, a Magnetic Resonance Image (MRI) may be ordered to assess damage to soft tissue such as ligaments, tendons, and cartilage. An MRI is a non-operative procedure that allows the surgeon to determine the amount of damage to the ACL and any other structures of the knee.
If further testing is needed to clearly evaluate the problem, an arthroscopy may be recommended. During an arthroscopy, a tiny fiberoptic scope is inserted into the joint. The doctor uses this scope to visually assess the damage. In most cases, a diagnosis can be made without using this surgical procedure.