OVERVIEW

Which joints in the lower limb are included in lower limb joint dislocations?

The lower limb has three major joints:

• The hip joint, which connects the thigh and the buttocks;
• The knee joint, which connects the thigh and the lower leg;
• The ankle joint, which connects the lower leg and the foot.

Additionally, there are joints in the foot:

• The tarsometatarsal joint at the high arch of the foot;
• The metatarsophalangeal joint, which connects the toes and the sole;
• The interphalangeal joints between the toe bones, etc.

Which joint is most commonly dislocated in lower limb joint dislocations?

Among lower limb joint dislocations, hip joint (the joint connecting the thigh and buttocks) dislocations are the most common, while knee and ankle joint dislocations are less frequent. Knee or ankle dislocations are often caused by significant trauma, so ligament injuries or fractures often accompany dislocations in these areas.

SYMPTOMS

What is hip dislocation?

The bones that make up the hip joint include the femoral head and the acetabulum of the hip bone. The acetabulum is like a mortar, and the femoral head is like a pestle, allowing movement in all directions within the acetabulum. When the femoral head moves out of the acetabulum, it is called hip dislocation.
Depending on the position of the femoral head, hip dislocation can be classified into posterior dislocation, anterior dislocation, and central dislocation.
Because hip dislocation is often caused by trauma, it is frequently accompanied by fractures of nearby bones, such as femoral head fractures, acetabular fractures, or femoral neck fractures. Immediate medical attention is required.

What are congenital hip dislocation and developmental dysplasia of the hip?

Congenital hip dislocation has now been renamed developmental dysplasia of the hip (DDH). This is because hip dislocation in children is not necessarily an inborn condition but is also related to postnatal development (in most cases).
Hip dysplasia refers to abnormalities in the size, shape, orientation, or histology of the femoral head or acetabulum, or both. Acetabular dysplasia is characterized by an underdeveloped and shallow acetabulum, which can lead to partial or complete dislocation of the femoral head. Hip subluxation occurs when the femoral head shifts from its normal position but remains partially covered by the acetabulum. Complete hip dislocation means there is no contact between the articular surface of the femoral head and the acetabulum.

What is knee dislocation?

The knee joint consists of the tibia (shinbone), femur (thigh bone), patella (kneecap), and surrounding ligaments. The knee is the largest and most complex joint in the human body.
The stability of the knee joint is maintained by bone structure, menisci, fat pads, ligaments, joint capsules, and surrounding muscles. The most important stabilizing ligaments are the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL). If these ligaments are torn, knee dislocation may occur.
Knee dislocation is relatively rare, and knee instability is more common.

What is knee instability?

Knee instability primarily manifests as susceptibility to sprains, a sensation of joint shifting or looseness, difficulty with sudden stops or turns, and pain during running or jumping.
The main stabilizers of the knee are the ACL, PCL, MCL, and LCL. Tears or complete ruptures of these ligaments can lead to knee instability.

What is ankle dislocation?

Pure ankle dislocation is relatively rare and is usually accompanied by fractures. Ankle injuries where dislocation is the primary issue, with only minor fractures, are referred to as ankle dislocations. Ankle fractures are often caused by excessive internal or external rotation, typically due to significant external force. Lesser twisting forces may result in an ankle sprain rather than dislocation.

What is Lisfranc joint dislocation?

The Lisfranc joint is located at the high arch of the foot, also known as the tarsometatarsal joint. Injuries to this joint are called Lisfranc injuries. Lisfranc joint dislocation is often caused by direct trauma, such as heavy objects falling on the foot, leading to joint separation and dislocation. It is usually accompanied by fractures, resulting in severe pain and foot deformity.

What is metatarsophalangeal joint dislocation?

The metatarsophalangeal joint connects the toes to the foot. The first metatarsophalangeal joint is the most commonly dislocated. The affected joint is painful, deformed, and difficult to move.

CAUSES

What are the common causes of hip dislocation?

Hip dislocation mainly occurs in young people due to severe trauma, such as car accidents or falls.

Is developmental dysplasia of the hip hereditary?

The shift from the previous term "congenital hip dislocation" was made to change societal perceptions. Regarding heredity, it can be understood this way: If your parents or siblings have developmental dysplasia of the hip, your risk of developing the condition is 35 times higher than that of the general population. This means you are far more likely to develop it than others, but it is not guaranteed. Children with such a family history should undergo regular pediatric orthopedic check-ups and follow-ups after birth to detect potential abnormalities early. Many factors can be mitigated through proper posture.

What are the common causes of tarsometatarsal joint dislocation?

Tarsometatarsal joint dislocation is mostly caused by direct heavy object impacts leading to joint separation.

What are the common causes of metatarsophalangeal joint dislocation?

Metatarsophalangeal joint dislocation often occurs from kicking objects or falling from heights.

DIAGNOSIS

How to diagnose a dislocated hip joint?

First, there must be a severe traumatic injury, such as a car accident. Second, the hip joint will be extremely painful, worsening with movement, and locked in a specific position where even slight motion causes intense pain. X-rays and CT scans can confirm the dislocation and check for any accompanying fractures.

What tests are needed to diagnose developmental dysplasia of the hip (DDH)?

X-ray examinations are ineffective for infants under 6 months old because the femoral head does not ossify until after 6 months of age, making it visible on X-rays.
Ultrasound imaging has become the most common and useful method for analyzing hip joint conditions, especially in infants under 6 months. Ultrasound is highly sensitive in assessing hip position, acetabular development, and joint instability, providing more accurate results than X-rays. This technique can be used as a screening tool for initial neonatal hip examinations, as well as for monitoring high-risk infants with DDH and tracking disease progression.
However, not all hospitals offer this specialized procedure, so consulting a local children's hospital is recommended.

How to diagnose a Lisfranc (tarsometatarsal) joint dislocation?

X-rays can definitively diagnose a Lisfranc joint dislocation, determine the direction of displacement, and identify any associated fractures.

TREATMENT

Why does closed reduction treatment for hip dislocation require going to the operating room even without surgery?

Because hip joint reduction needs to be performed under anesthesia in the operating room.
The hip muscles are very strong, and doctors perform the reduction manually. As the saying goes, "the arm is no match for the thigh." In this case, anesthesia is required to relax the entire body and muscles for successful reduction. Without anesthesia, excessive force would be needed to reposition the dislocated femoral head into the acetabulum, which could cause further damage. Therefore, anesthesia is recommended.

Will there be sequelae after hip dislocation?

Sequelae after hip dislocation are mainly caused by complications, such as sciatic nerve injury, femoral head necrosis, and hip osteoarthritis.

Can developmental dysplasia of the hip (DDH) be cured?

Early detection and standardized treatment can lead to a full recovery. Early diagnosis is crucial—the sooner, the better. For this reason, screening programs have been implemented in Europe and the U.S., and China is also adopting them. At six months old, the hip joint has strong remodeling capacity, making this the optimal time for treatment.

Will there be sequelae after treatment for developmental dysplasia of the hip?

This depends on the timing and standardization of treatment. Generally, treatment before the age of 4 yields better recovery, with the hip joint potentially developing close to normal. The later the treatment, the more difficult and less effective it becomes. If treatment is delayed, hip pain or even mobility impairment may occur as early as 15–25 years of age, requiring surgical intervention.

How is metatarsophalangeal joint dislocation treated?

The primary treatment is manual reduction, with surgery rarely needed. The foot is stabilized with one hand while the toe is gently pulled to reposition it. After reduction, a cast is applied for 3–4 weeks.

DIET & LIFESTYLE

Can you get out of bed immediately after a hip dislocation?

No, even after successful closed reduction (without surgery), you should stay in bed for 3-4 weeks and undergo 3-4 weeks of skin traction. This involves placing padded devices on the thigh and lower leg, then using weights to pull the lower limb straight. The purpose of bed rest and traction is to stabilize the hip joint and allow proper healing of the surrounding ligaments and joint capsule.
If a fracture is also present, bed rest for 4 weeks is undoubtedly required.

PREVENTION

Can Developmental Dysplasia of the Hip Be Prevented? How?

Yes, it can be prevented. To understand prevention, the causes must first be identified. Research shows that breech pregnancy (where the fetus is positioned feet-first instead of head-first before birth) and swaddling with legs tightly bound are significant contributing factors.

• In regions where baby-wearing is common, such as Guangxi and Guizhou, the incidence of this condition is low. This is because infants in carriers are positioned with hips flexed and abducted, allowing better alignment of the femoral head with the acetabulum, which promotes healthy development.

• Another harmful practice is swaddling infants with their hips straightened, like "straight sticks," mistakenly believed to prevent bowlegs. In reality, this does not prevent bowlegs but increases the risk of hip dysplasia.

• In breech pregnancies, hip instability or even dislocation can easily occur during delivery, whether due to external traction or spontaneous rotation.

• Additionally, developmental hip dysplasia is associated with congenital laxity of the hip joint capsule and ligaments, as well as femoral head developmental abnormalities.

The causes are not singular but multifactorial.
Thus, the key to prevention lies in early detection. Some provinces and cities have already implemented screening programs for hip dislocation.