A genetic disorder that presents at birth with multiple dislocated joints and spinal problems.
My approach to Larsen Syndrome is unique and requires its own discussion. Most often, infants are born with multiple dislocated joints and spinal involvement. The joints of Larsen Syndrome must be treated as young as possible in order to allow the joints to become stable and round to function. While in many conditions, we often wait until the child is a bit older, perhaps 3-6 years of age, before undergoing significant management, Larsen Syndrome may require relocation of joints even surgically as young as 3-6 months of age.
Regarding the hip and knee joints, they need to be relocated and often stabilized. In the case of the hip, with deepening the socket and changing the angle of the femur bone rotationally and in terms of it pointing to the socket. The knees often need to have ligaments reconstructed, even in young children, to allow for stability.
Most joints of the upper and lower extremities can be reduced, first with bracing/casting and then surgically, if necessary. Any spinal instability or compression must be treated at a young age as well. Most Larsen Syndrome patients should be walking and leading productive “normal” lives.
Larsen Syndrome is a genetic disorder that congenitally involves multiple dislocated joints including hip, knees and elbows. The spine may also suffer from congenital kyphosis and scoliosis. Clubfeet and or vertical talus with dislocated joints in the foot is also quite common.
Larsen Syndrome impacts one in one hundred thousand individuals worldwide. Symptoms vary widely even within a family. Commonly, multiple joints are dislocated and contracted. Despite weakness, muscles are present and functioning. Joint surfaces are not round and may not be congruent, meaning they don’t match up making functional movement challenging. All joints of the extremities may be involved from shoulders to hands and from hips to toes. The spine can be very challenging and left untreated can lead to paralysis
Larsen Syndrome is most often associated with a genetic autosomal dominant defect in the FilaminB gene (FLNB). There are many problems that may occur in the gene of FLNB. Each defect may present differently in the affected individual and may be missed when genetic testing is performed.
The diagnosis is made on clinical grounds of multiple dislocated joints and the Filamin gene involvement. While Larsen Syndrome is often lumped into “arthrogryposis” like syndromes, it is truly its own disorder with very specific features. While arthrogryposis means “stiff joints” and presents with the absence of muscles, or ones that are stiff and weak, Larsen Syndrome has dislocated joints and the muscles are present.
Each joint dislocation must be treated independently and early in infancy. Casting and splinting is necessary and may help avoid the need for surgery on the knees, feet and even elbows. Surgery, to reconstruct and reduce joints and reconstruct ligaments may be needed. If so, when performed early enough, joints are found to develop more normally.