Congenital Knee Dislocation (CDK) is a rare disorder that is present at the time of birth. It is a physical deformity that affects the alignment of the knee joint and may exist in isolation or could be a consequence of some musculoskeletal abnormality. It is characterized by a hyperextension of the knee, along with a possible misalignment or dislocation of the foot and hip joint as well. Congenital Knee Dislocation may promote the chances of a breech birth and it is more common in girls.
Causes
- Family history or genetic factors
- Larsen Syndrome which refers to faulty development of knee, hip or foot joints
- Neural Tube Defect – The spinal cord and meninges or the tissues covering it do not close and start protruding out of the baby’s back
- Abnormal fetal position in the womb
- Primary contracture of the quadriceps muscles
- Traumatic dislocation may also occur during parturition (vaginal birth)
- Underdevelopment or complete absence of the cruciate ligaments in the knee joint
Symptoms
- The child will be born with a clear knee recurvatum, i.e., backward bent knee
- Club Foot
- The child may also have an abnormal rib cage or chest cavity
- The hip joint may also be dislocated
- The knee cap is partially formed and may not be found during palpation
Diagnosis
- A thorough clinical evaluation of the child’s limbs and adjacent parts may be done using palpation
- The flexibility and range of motion of the joint may be assessed
- An ultrasound test conducted during the gestation period may reveal the problem
- X-ray imaging to assess the severity of the deformity MRI scan may be recommended for children 3 years of age
Treatment
In most cases, non-surgical treatment options are recommended for Congenital Knee Dislocation. Orthopedic doctors recommend that starting the treatment soon after birth enhances the chances of recovery. Treatment options may include:
- The hip and knee may be manipulated using external fixators to bring them back to their original position. These fixator devices may be used till the child attains the age of six months
- Use of splints on the affected part may be helpful
- Skin traction
- Percutaneous Quadriceps Recession – A minimally invasive surgical technique which aims at correcting the joint alignment
- Serial casting – Use of a fiberglass plaster to hold the deformed limb in the correct position and stretch the tight muscle to control its flexion. A new cast may be fixed every week and the treatment is likely to continue for 3-6 weeks
- Surgical lengthening of the quadriceps or the tendons of the knee cap (patellar tendons) may be required at a later stage
- Leg brace may be worn to allow limited flexion of the knee
- Surgical repositioning of the displaced bones and reconstruction of supporting ligaments
- Strengthening the quadriceps muscles through physical therapy may be recommended
