Flexion Contracture of the Knee - A Detailed Review

Introduction

To maintain good health and wellness, one must move their joints through their complete range of motion (ROM). People who are unable to do so struggle to do everyday tasks like walking or eating. A contracture is a loss of joint range of motion. A bent joint that cannot be actively or passively straightened is said to have a flexion contracture. The structural changes in the ligaments, tendons, or muscles hinder normal joint mobility leading to loss of movement of the joints.

What Is the Flexion Contracture of the Knee?

The inability of the knee to fully extend or straighten is referred to as flexion contracture and is a flexion deformity of the knee. The knee may extend 0° and flex 140° in its normal active range of motion (AROM). This is best described as having a restricted range of active and passive knee extension. It occurs when the hamstrings, or the knee flexors, are unable to stretch along with the bone, especially when physical treatment is insufficient to offer both active and passive mobilization of the injured joint. Typically, it consists of a mix of ligamentous, capsular, and bony deformities. They frequently need lengthy recovery and proper rehabilitation. Flexion defects are often bilateral. The bone defect can be permanent or transient.

What Are the Types of Flexion Contracture?

Different factors can lead to flexion defects. There are two distinct recognized forms of knee flexion contracture.

• Flexion Contractures Related to Ankylosis and Joint Destruction:

  • Osteoarthritis (arthritis type leading to the deterioration of cartilage).

  • Rheumatoid arthritis (an autoimmune condition that causes persistent inflammation and affects several joints, especially of feet and hands).

  • Pathologies of the ankle.

  • Injuries of the hip joint.

  • Cerebral palsy (a condition where a person's mobility, balance, and posture are impacted).

  • Poliomyelitis or polio (caused by the polio virus can result in disability or fatality).

  • Osteogenesis imperfecta (a class of hereditary diseases marked by bones that are brittle and can be broken easily).

  • Pterygium syndrome (an extremely uncommon genetic condition known as pterygium syndrome is characterized by small facial deformities, low height, spinal malformations, webbing (pterygia) of the neck, and several joints set in place or contractures).

  • Other degenerative disorders of the bone.

• Flexion Contractures Related to the Anatomy and Mobility of the Joints:

  • Tendon transfers.

  • Scar tissue.

  • After the operation on the knee (total knee arthroplasty).

  • Stiffness encountered after femur, patella, tibia, or total knee joint fracture.

What Is the Clinical Presentation of Flexion Contracture of the Knee?

• Individuals who have flexion contractures frequently walk with bent knees.

• Patients frequently describe sleeping in the fetal position or with a pillow beneath their knee.

• The flexion contracture is made worse by the above-mentioned actions. When the flexion deformity is greater than 15 degrees of extensor lag (a condition mainly seen in injured knees or the knees recovering from surgery. Here, the active range of knee extension is smaller than the passive range), it results in a greater strain on the quadriceps and increased strain forces generated by contact in the tibiofemoral joint and patellofemoral joint.

• The main muscles surrounding the hip and ankle joint, such as the iliopsoas, hamstrings, gastrocsoleus, quadriceps, and adductors or abductors of the hip, depending on whether there is a secondary abnormality of either genu varum or genu valgum and patella alta, are also affected by early joint degeneration, which includes the cartilage deterioration, meniscal injury, ligament strains, and associated tightness of TFL (tensor fascia lata).

What Is the Grading System for Flexion Contracture of the Knee?

• Grade I: Minimal contracture with a deformation that is just 15° or less.

• Grade II: A deformity between 15° and 30° and moderate contracture.

• Grade III: A deformity greater than 30°and severe contracture.

What Are the Noticeable Gait Changes Seen in Flexion Contracture of the Knee?

• The distance walked by a patient is reduced.

• At the start of the stance phase as well as throughout the gait cycle, the knee is flexed. There is a reduction in the popliteal angle. When the extensor lag is less than 15 degrees, the absence of heel strike is noted. Toe walking is seen in the patient when the extensor lag is greater than 15 degrees.

• In the swing phase, the hip flexion increases, and the body is driven forward.

• The stride length shortens while walking with a limp and progressive crouch gait.

• Other clinical signs are a pain in the anterior knee and deformity of the hip flexion, followed by lumbar lordosis (inward curve of the lower back).

• Severe contractures of the knee, hip, and patella alta are changes that develop later. Knee flexion contracture has a major impact on the three-dimensional trunk kinetics while walking, standing, and in a relaxed state. This causes spinal imbalance. The common peroneal nerve, tibial nerve, and other popliteal fossa contents may all experience pressure as a result of continual strain on the popliteal fossa.

How Is Flexion Contracture of the Knee Managed?

Different therapeutic strategies are required depending on the cause and extent of the deformity. Knee flexion contractures can be treated surgically and non-surgically. Physiotherapy is required in both situations. Physical therapy, at-home workout routines, and mechanical therapy at the house are examples of conservative therapies. These are employed to prevent and cure flexion contractures. Management of spasticity is also important in some circumstances, such as cerebral palsy. The use of a tool called an extensionator is another technique that can assist in straightening a knee.

• Physiotherapy Management: Some of the physical therapy techniques that can be used are:

  • Stretching manually.

  • Using a tilt table for prolonged stretching.

  • Prolonged stretching using a sandbag.

  • Using weight on the distal femur.

  • Mechanical traction.

  • Exercises involving passive range-of-motion.

  • Mobilization of the joints.

The amount of torque applied, together with the therapy's length and frequency, all affect how well a certain treatment works to lessen flexion contractures.

• Medical Management-

  • Casting, bracing, and orthoses are all types of therapy used in the medical management of the flexion contracture of the knee. Some splits have been advertised as an alternative method to apply mild stretching forces over the course of time. They offer flexion resistance, allowing the knee to be at rest even during its fullest extension. One can increase the resistance in such devices. They are simple to use, portable, and patient-friendly. Splints and orthoses are often used to stop deformities or preserve the range of motion after extending and stretching rather than to increase motion.

  • For more serious cases, surgery may be required, including the release of soft tissue, osteotomies (when a portion of the bone is removed), femoral shortening, hamstring lengthening, and rectus transfer. Excessive contractures can be relieved with hamstring lengthening, especially if they have a big impact on gait. Particularly in individuals with cerebral palsy, rectus transfer may be recommended to partially alleviate the spasticity of the quadriceps.

  • The abnormality might return and result in prolonged flexion contracture despite all surgical attempts and post-operative rehabilitation techniques. In order to correct the malformation in such individuals, manipulation under anesthesia is required.

Conclusion

A complete passive range of motion (ROM) of a joint is restricted in joint contractures, and this has a significant negative impact on public health. It can inhibit essential everyday tasks like dressing and eating, limit movement, have a severe influence on the quality of life, and limit an individual's work and earning capacity. The geriatric population is more susceptible to contractures as a result of comorbid conditions that have built up over time and have caused limited joint mobility, and over time, ROM loss. Knee contracture or flexion contracture of the knee is mainly associated with conditions such as arthritis and osteoarthritis. With proper treatment and care, patients might be able to perform their daily tasks.