Coxa vara
Encyclopedia
Coxa vara is a deformity
of the hip, whereby the angle between the ball and the shaft of the femur
is reduced to less than 120 degrees. This results in the leg being shortened, and therefore a limp
occurs. It is commonly caused by injury, such as a fracture. It can also occur when the bone tissue in the neck of the femur
is softer than normal, meaning it bends under the weight of the body. This may either be congenital, also known as Mau-Nilsonne Syndrome, or the result of a bone disorder. The most common cause of coxa vara is either congenital or developmental. Other common causes include metabolic bone diseases (e.g. Paget's disease of bone
), post Perthes
deformity, osteomyelitis
, and post traumatic (due to improper healing of a fracture between the greater
and lesser trochanter
). Shepherds Crook deformity is a severe form of coxa vara where the proximal femur is severely deformed with a reduction in the neck shaft angle beyond 90 degrees. It is most commonly a sequela of osteogenesis imperfecta
, Pagets disease, osteomyelitis
, tumour and tumour-like conditions (e.g. fibrous dysplasia
).
). In severe cases abduction maybe severely restricted, causing a waddling type gait.
The biomechanics of the hip will be affected as the lever arm is lengthened causing more shear forces through the femoral neck predisposing it to stress fractures. This may also lead to progression of the deformity.
(due to restriction of abduction). Trendelenburg's sign
maybe positive.
Synonyms are Femoral Angle and Mikulicz's angle. When a patient is positioned for a radiographic image attempting to demonstrate Coxa Vara it is important that the technician insures that the patient medially rotates the foot 15° on the ipsilateral side (same side) being depicted in the film.
.
Deformity
A deformity, dysmorphism, or dysmorphic feature is a major difference in the shape of body part or organ compared to the average shape of that part.Deformity may arise from numerous causes:*A Genetic mutation*Damage to the fetus or uterus...
of the hip, whereby the angle between the ball and the shaft of the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
is reduced to less than 120 degrees. This results in the leg being shortened, and therefore a limp
Limp
A limp is a type of asymmetric abnormality of the gait. Limping may be caused by pain, weakness, neuromuscular imbalance, or a skeletal deformity. The most common underlying cause of a painful limp is physical trauma however in the absence of trauma other serious causes such as septic arthritis,...
occurs. It is commonly caused by injury, such as a fracture. It can also occur when the bone tissue in the neck of the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
is softer than normal, meaning it bends under the weight of the body. This may either be congenital, also known as Mau-Nilsonne Syndrome, or the result of a bone disorder. The most common cause of coxa vara is either congenital or developmental. Other common causes include metabolic bone diseases (e.g. Paget's disease of bone
Paget's disease of bone
Paget's disease is a chronic disorder that can result in enlarged and misshapen bones. The excessive breakdown and formation of bone tissue causes affected bone to weaken, resulting in pain, misshapen bones, fractures, and arthritis in the joints near the affected bones...
), post Perthes
Perthes
Perthes is the name of three communes in France:* Perthes, Ardennes, in the Ardennes département* Perthes, Haute-Marne, in the Haute-Marne département* Perthes, Seine-et-Marne, in the Seine-et-Marne départementAs a German surname:...
deformity, osteomyelitis
Osteomyelitis
Osteomyelitis simply means an infection of the bone or bone marrow...
, and post traumatic (due to improper healing of a fracture between the greater
Greater trochanter
The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system.It is directed a little lateralward and backward, and, in the adult, is about 1 cm lower than the head...
and lesser trochanter
Lesser trochanter
The lesser trochanter of the femur is a conical eminence, which varies in size in different subjects-Anatomy:It projects from the lower and back part of the base of the femur neck.From its apex three well-marked borders extend:...
). Shepherds Crook deformity is a severe form of coxa vara where the proximal femur is severely deformed with a reduction in the neck shaft angle beyond 90 degrees. It is most commonly a sequela of osteogenesis imperfecta
Osteogenesis imperfecta
Osteogenesis imperfecta is a genetic bone disorder. People with OI are born with defective connective tissue, or without the ability to make it, usually because of a deficiency of Type-I collagen...
, Pagets disease, osteomyelitis
Osteomyelitis
Osteomyelitis simply means an infection of the bone or bone marrow...
, tumour and tumour-like conditions (e.g. fibrous dysplasia
Fibrous dysplasia
Fibrous dysplasia is a disease that causes bone thinning and growths or lesions in one or more bones, and leads to bone weakness and scar formation within the bones.-Presentation:...
).
Symptoms
The condition is asymptomatic if congenital or developmental. However in unilateral cases (eg. post traumatic), there may be shortening, leading to a short limb gait characterised by limp which is seen as a vertical dip on the affected side during the stance phase (as opposed to a lurch characterised in a Trendelenburg gaitTrendelenburg gait
The Trendelenburg gait pattern is an abnormal gait caused by weakness of the abductor muscles of the lower limb, gluteus medius and gluteus minimus. People with a lesion of superior gluteal nerve have weakness of abducting the thigh at the hip...
). In severe cases abduction maybe severely restricted, causing a waddling type gait.
The biomechanics of the hip will be affected as the lever arm is lengthened causing more shear forces through the femoral neck predisposing it to stress fractures. This may also lead to progression of the deformity.
Diagnosis
The diagnosis is mainly radiological. Clinical signs include a widened bitrochanteric measurement. The patient may have a short limbed gait, or in severe cases a Trendelenburg gaitTrendelenburg gait
The Trendelenburg gait pattern is an abnormal gait caused by weakness of the abductor muscles of the lower limb, gluteus medius and gluteus minimus. People with a lesion of superior gluteal nerve have weakness of abducting the thigh at the hip...
(due to restriction of abduction). Trendelenburg's sign
Trendelenburg's sign
Trendelenburg's sign is found in people with weak or paralyzed abductor muscles of the hip, namely gluteus medius and minimus. It is named after the German surgeon Friedrich Trendelenburg....
maybe positive.
Synonyms are Femoral Angle and Mikulicz's angle. When a patient is positioned for a radiographic image attempting to demonstrate Coxa Vara it is important that the technician insures that the patient medially rotates the foot 15° on the ipsilateral side (same side) being depicted in the film.
Treatment
Treatment depends on the cause of the condition. Most cases do not require any treatment. If treatment is required, it is usually a valgus osteotomy of the femur fixed by an angled blade plate device or even a dynamic hip screwDynamic hip screw
Dynamic hip screw or Sliding Screw Fixation is a type of orthopaedic implant designed for fixation of certain types of intertrochanteric and subtrochanteric fractures which allows controlled dynamic sliding of the femoral head component along the construct...
.
See also
- Coxa valgaCoxa valgaIt is a deformity of the hip where the angle formed between the head and neck of the femur and its shaft is increased, usually above 135 degrees. It is caused by a slipped epiphysis of the femoral head.-See also:*Coxa vara*Genu valgum*Genu varum...