Why is my leg no longer straight from the knee?

The knee generally refers to the knee joint. In most cases, a lack of full extension or straightening of the knee may result from intra-articular adhesions, bony deformities, soft tissue contractures behind the knee joint, knee injuries, or knee arthritis. Patients are advised to follow medical guidance for appropriate treatment based on the underlying cause. Detailed analysis is as follows:

1. Intra-articular Adhesions

This condition commonly occurs after injuries around the knee joint, such as fractures or dislocations. During recovery, prolonged immobilization can lead to scar tissue formation and adhesions within the joint. If patients do not actively engage in functional exercises, these adhesions may progressively worsen, eventually leading to limited knee extension—manifesting as an inability to fully straighten the knee. Treatments such as moxibustion and acupoint massage may be used as adjunctive therapies.

2. Bony Deformity

For example, if a patient previously suffered a severe fracture in the surrounding area that was not properly treated medically, residual bony deformity may occur. This can result in persistent misalignment or apparent lack of knee straightening even during attempted extension. Treatment options depend on the severity of the deformity and may include conservative management or surgical intervention. For instance, supernumerary digits (such as six fingers) may be surgically removed and corrected. Bowlegs or genu valgum can be corrected through conservative methods such as massage, manipulation, or bracing if mild; however, more severe cases may require surgical correction under medical supervision.

3. Soft Tissue Contracture Behind the Knee Joint

This condition often results from prolonged immobilization of the knee joint. When the knee remains fixed in a flexed position for an extended period, the posterior soft tissues—such as tendons or fascia—may develop contractures, which over time restrict full extension. Additionally, soft tissue contractures caused by burns or similar factors can also lead to this problem. Treatment typically includes physical therapy or surgery under medical guidance, along with exercise therapy, all of which can effectively alleviate symptoms of knee contracture.

4. Knee Joint Injury

If a patient sustains a knee injury, it may lead to rupture of the medial collateral ligament, resulting in the aforementioned symptoms. It is recommended that patients rest adequately to reduce joint loading and promote healing. Cold or heat compresses may help relieve pain and swelling.

5. Knee Arthritis

Inflammatory conditions affecting the knee may cause symptoms such as pain and swelling. In severe cases, this inflammation may also lead to impaired knee extension, causing the knee to appear bent or not straight. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as celecoxib capsules or meloxicam tablets, may be used under medical supervision to reduce inflammation and relieve pain.

In addition, soft tissue contractures at the back of the knee due to burns or other causes can also result in an inability to straighten the knee. Patients are advised to seek timely medical evaluation at a hospital to determine the exact cause and receive appropriate, targeted treatment.