Boyd W. Haynes III, MD
The knee joint plays a vital role in our everyday function and mobility. Limited range of motion in the knee can significantly impact our quality of life and daily activities. Identifying the underlying cause of restricted knee mobility is essential for accurate diagnosis and effective treatment. Here, I’ll discuss the potential diagnoses associated with limited range of motion in the knee.
Before delving into limited knee range of motion, let’s establish the normal range of motion in a healthy knee joint. The knee joint allows flexion and extension movements, as well as slight rotation. The normal range of motion typically includes flexion up to 135-155 degrees, extension to 0 degrees, and a slight degree of internal and external rotation. Of course, there are those folks who are hypermobile and flexible, but they left to join the circus or the Olympic gymnastic team, so we won’t deal with them here.
So, what are the most common reasons for limited range of motion in the knee?
- Osteoarthritis – the Biggie!
Osteoarthritis is a degenerative joint disease that can lead to limited range of motion in the knee. Joint space narrowing, osteophyte (bone spur) formation, and cartilage erosion contribute to pain, stiffness, and reduced mobility.
- Meniscal Tears
Meniscal tears, particularly in the medial or lateral knee menisci, are another frequent cause of limited range of motion. These injuries can occur due to trauma or degenerative changes. Meniscal tears can cause mechanical symptoms, such as catching or locking of the knee joint, leading to restricted movement.
- Autoimmune Conditions
Rheumatoid and psoriatic arthritis are often associated with limited knee range of motion and are characterized by cartilage breakdown and joint inflammation, leading to pain, stiffness, and reduced mobility. Rheumatoid and psoriatic arthritis, autoimmune diseases, cause chronic inflammation and joint destruction, resulting in joint deformities and restricted motion.
- Patellofemoral Disorders
Patellofemoral disorders encompass a range of conditions that can cause limited knee range of motion, including patellofemoral pain syndrome, patellar tendinitis, and patellar instability. These conditions often manifest with anterior knee pain, crepitus, and difficulty with activities such as climbing stairs or squatting.
- Traumatic Injuries
A common cause of limited knee range of motion is traumatic injuries, such as ligamentous sprains, meniscal tears, or fractures. These injuries can lead to pain, swelling, and instability, resulting in reduced joint movement. Ligamentous injuries, such as an anterior cruciate ligament (ACL) tear, can cause instability and subsequent muscle guarding, leading to restricted knee range of motion.
- Inflammatory Diseases
Inflammatory diseases, including gout, pseudogout, and infectious arthritis, can also contribute to limited knee range of motion. Gout is caused by the deposition of uric acid crystals in the joint, leading to acute episodes of inflammation and joint stiffness. Pseudogout, on the other hand, involves the deposition of calcium pyrophosphate crystals and can mimic the clinical presentation of gout. Infectious arthritis, caused by microbial invasion of the joint, results in pain, swelling, and restricted motion.
- Postoperative Complications
Limited knee range of motion can occur from postoperative complications following knee surgery, such as arthroscopy, ligament reconstruction, or joint replacement. Factors contributing to restricted motion include scar tissue formation, joint contractures, or inadequate rehabilitation.