Article by Dr Manasa S, B.A.M.S
Knee instability is a prevalent condition often stemming from injuries or complications affecting the ligaments within the knee joint. This instability manifests as a sensation of the knee “giving out” or buckling, particularly when subjected to pressure. Such issues arise when the ligaments fail to securely hold the bones in place. This results in a wobbly feeling while bearing weight on the knees. Among the most common contributors to knee instability are tears in the Anterior Cruciate Ligament (ACL), Medial Collateral Ligament (MCL), and Posterior Cruciate Ligament (PCL).
Certain demographic groups face a higher risk of experiencing knee instability, particularly individuals engaged in strenuous physical activities such as athletes, dancers, and those with physically demanding occupations. Other risk factors include obesity, gender (with women being more susceptible), advanced age, and a history of previous knee injuries. Understanding the causes and symptoms of knee instability is crucial for prompt diagnosis and appropriate management to prevent further complications and restore optimal knee function.
Brief anatomy of knee joint
Knee joint is a part of the skeletal system which is made up of cartilages, muscles, ligaments and nerves. Knee joint is considered as the biggest joint of the body which connects the thigh bone [femur] to shin bone [tibia]. Knee joint helps to bear the weight of the body, helps in movement of legs and takes part in activities like walking, running and jumping and is also concerned with stability while standing and thus plays an important role in keeping the balance of the body intact.
The knee is classified as a synovial joint, characterized by its extensive range of motion. Comprising a cavity in one bone that accommodates another bone, synovial joints feature slippery hyaline cartilage covering the bone ends, along with a synovial membrane filled with fluid, which serves to lubricate and safeguard the joint, reducing friction during movement.
Functionally, the knee operates as a hinge joint, similar to the hinges of a door, allowing movement primarily in one direction—opening and closing. Structurally, the knee consists of bones, cartilage, ligaments, muscles, and nerves. The three primary bones involved are the femur, tibia, and patella, each with distinct articulations: the patellofemoral junction and the tibiofemoral junction.
Cartilage within the knee includes hyaline cartilage, which lines the joint surfaces, facilitating smooth movement, and fibrocartilage, such as the meniscus, which provides cushioning and stability.
Ligaments, connecting bone to bone, are categorized into collateral (medial and lateral) and cruciate (anterior and posterior), which respectively restrict side-to-side and front-to-back movement of the knee.
Muscles surrounding the knee, including flexors and extensors, contribute to its movement by flexing and extending the joint. Notable muscles involved include the rectus femoris, vastus muscles, biceps femoris, and gastrocnemius, among others. Lastly, nerves such as the femoral, sciatic, tibial, and peroneal nerves innervate the knee, facilitating sensory perception and muscle control.
Knee stability and instability
Movements at the knee joints are a complex mechanical phenomenon. Knee stability is provided by a combination of a lot of structures that work together to prevent excessive movement or instability at the joints. Stability is maintained by the shape of the condyles, menisci in combination with four supporting structures like, the anterior cruciate ligament [ACL], the posterior cruciate ligament [PCL], the medial collateral ligament [MCL], and lateral collateral ligament [LCL]. The anterior cruciate ligament [ACL] is a main ligament that gives stability to the knee joint. Instability resulting mainly from ligament injury may be due to direct or indirect trauma.
Causes of knee instability
The main reasons behind knee instability are damage to supporting ligaments, knee osteoarthritis or a mechanical issue. It may also occur after an injury or for no reason at all. The following are the causes for the instability of knee joints.
Injury of the ligaments
For individuals actively engaged in sports, knee injuries are a common concern. These injuries often involve damage to the ligaments that stabilize the knee joint, including the anterior cruciate ligament (ACL), medial collateral ligament (MCL), lateral collateral ligament (LCL), and posterior cruciate ligament (PCL).
ACL injuries typically occur during quick pivoting movements, while MCL and LCL injuries often result from impacts. PCL injuries, on the other hand, are frequently associated with direct blows to the front of the knee, such as those sustained in car accidents.
Lifestyle related activities
Various activities like impact, twisting, jumping, or sudden stops can lead to ligament damage, resulting in partial tears or complete ruptures.
Knee osteoarthritis
Furthermore, knee instability in older adults is commonly linked to knee osteoarthritis, a degenerative condition characterized by the breakdown of knee cartilage. Symptoms include pain, swelling, and decreased mobility.
Patellar instability
Another issue related to knee stability is patellar instability, where the kneecap (patella) is displaced either partially (subluxation) or completely (dislocation) from its groove. This condition can result from injury or knee deformity.
Other causes
– Knee strains and sprains
– Gouty arthritis
– Infection in the joint
– Meniscus tear
– Bursitis of knee
Types of knee instability
Types of knee instability according to duration and symptoms of instability
Physicians commonly categorize knee instability into three distinct types according to duration and symptoms
1. Simple Knee Joint Instability: This classification pertains to instances where only one of the knee’s structures is compromised, such as the medial collateral ligament.
2. Complex Knee Joint Instability: This designation encompasses scenarios wherein multiple structures within the knee are concurrently affected. Examples include damage to the cruciate ligaments, collateral ligaments, the knee joint capsule, or the menisci.
3. Chronic Knee Joint Instability: This type denotes instability that has endured over an extended period, typically spanning several years.
Types of knee instability according to the anatomical position
Anterior Instability:
Instability in the anterior region may stem from injury to various structures, including:
– Anterior Cruciate Ligament (ACL)
– Partial or complete injury to the lateral capsular ligament
– Partial or complete injury to the medial capsular ligament
Posterior Instability:
Instability posterior to the knee may result from injury to:
– Posterior Cruciate Ligament (PCL)
– Partial or complete injury to the arcuate complex
– Partial or complete injury to the posterior oblique ligament
Medial Instability:
Instability on the medial aspect of the knee arises from injury to:
– Medial collateral ligament
– Medial capsular ligament
– Anterior Cruciate Ligament (ACL)
– Posterior oblique ligament
– Sometimes, the Posterior Cruciate Ligament (PCL)
Lateral Instability:
Instability on the lateral side of the knee is associated with injury to:
– Lateral collateral ligament
– Lateral capsular ligament
– Anterior Cruciate Ligament (ACL)
– Biceps tendon
– Partial or complete injury to the arcuate complex
– Iliotibial band (ITB
Signs and symptoms of ‘Knee Instability’
– Loud popping or snapping sound upon injury occurrence
– Sudden and severe pain manifestation
– Sensation of joint looseness experienced
– Inability to bear weight on the affected joint
– Swelling evident within the initial 24 hours
Common diagnostic tests
The following investigations are advised to know the cause for the knee instability, so that a prompt treatment and management protocol can be initiated and carried out effectively.
– X-ray
– MRI scans
– Ultrasounds
– CT scan
– Joint aspirations
Treatment and management of knee instability
Non-surgical treatment
The approach to treating knee instability varies based on its nature and severity.
One effective method is employing the RICE technique for at-home knee joint instability treatment:
– Rest: Ensure your knee gets ample rest to facilitate healing and diminish swelling.
– Ice: Apply an ice pack wrapped in cloth to alleviate pain and inflammation. Aim for icing the affected area two to three times daily for 10 to 20 minutes each session.
– Compression: Use an elastic bandage to wrap the injured area, effectively reducing swelling. Ensure the wrap isn’t overly tight to avoid tingling, pain, or exacerbating swelling.
– Elevation: Elevate the injured area on soft pillows while icing and whenever sitting. Positioning the injury above heart level aids in reducing swelling.
Additionally, wearing a knee instability brace provides supplementary support, while collaborating with a physical therapist aid in restoring muscular strength and mobility.
Consultation with orthopedics is a must regarding non-steroidal anti-inflammatory medications such as aspirin and ibuprofen.
In some cases, injections of corticosteroids to diminish inflammation or Hyaluronic Acid to lubricate the joint might also prove beneficial.
Surgical approach
1. Medial patellofemoral ligament (MPFL) repair: A surgical intervention aimed at reinforcing and restoring the integrity of the ligaments responsible for stabilizing the patella within the femoral groove.
2. MPFL reconstruction: A surgical procedure designed to substitute a damaged ligament by utilizing a hamstring tendon either from a donor source or harvested from the patient’s own body. This approach aims to restore stability to the patellofemoral joint.
3. Knee osteotomy (tibial tubercle transfer): An orthopaedic procedure employed to realign the alignment of the tibia, femur, patella, and associated connective tissues. This surgical technique necessitates an open approach, involving a larger incision and entails a lengthier recovery period compared to arthroscopic interventions.
4. Knee replacement: A surgical intervention indicated for the management of severe arthritis or recurrent dislocations of the knee joint. This procedure involves replacing the affected joint surfaces with prosthetic components to alleviate pain and restore function.
Common preventive measures
Maintaining optimal knee health involves:
1. Adhering to a personalized diet and exercise regimen.
2. Scheduling routine checkups with healthcare professionals and promptly addressing any knee-related concerns or alterations.
3. Utilizing appropriate protective gear during various activities, sports, or occupational tasks.
Specific preventive measures
Several modalities are available to aid in the prevention of knee injuries, encompassing balance training, plyometric training, and strength and resistance training.
Balance Training
Enhancing balance plays a pivotal role in injury prevention, particularly concerning ACL injuries. Various balance training exercises, such as single-leg balancing, heel-to-toe walking, and bodyweight manoeuvres like walking lunges and Bulgarian split squats, are recommended.
Plyometric Training
Plyometric exercises, commonly referred to as jump training, entail executing explosive movements involving jumps. Proper form, including landing with soft knees and maintaining shoulder-width stance, is crucial. Research indicates that plyometric exercises can effectively mitigate ACL injuries.
Strength and Resistance Training
The development of adequate muscle strength is fundamental in averting various types of injuries, including those affecting the knee. Incorporating bodyweight exercises such as squats and lunges can significantly bolster the muscles supporting the knee joint.
Ayurveda Perspective of ‘instability of knee joint’
There is a condition named ‘Janu Vishlesha’ mentioned amongst 80 kinds of Vata Nanatmaja Rogas – specific disorders caused by ‘only vata’. It translates to ‘instability of the knee joint’. So, knee instability is a vata disorder.
Janu Vishlesha can be caused either due to increase in vata or decrease in kapha. Kapha is located in the joints and keeps the joints lubricated and helps in easy movement and flexibility of joints, knee joint in this context. Vata on the other hand is responsible for all movements at the joints. When this vata gets aggravated, it can deplete kapha due to its dryness. Kapha decrease can happen independent of vata also.
Damage to snayu – ligaments and tendons and sandhi – joints are also contributory.
Injury is yet another cause of knee instability. Injury too is one of the chief causative factors of aggravation of vata.
Contamination of majjavaha srotas – channels of transportation of bone marrow, being afflicted by vatarakta (gout) following exposure to etiological factors for aggravation of both, vata and rakta, excessive exercises, diseases and deformities of asthi and sandhi (bones and joints), and suffering from diseases of the likes of sandhigata vata – osteoarthritis and amavata – rheumatoid arthritis are some of the common causes for sandhi vishlesha.
The treatment of janu vishlesha includes addressing vata and kapha imbalances and treating the diseases which are causal. The same treatments are applicable and very much helpful in treating knee instability.
Related Reading – Janu Vishlesha
