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Coxa Vara

Coxa vara constitutes a structural hip abnormality, where the intersection formed by the shaft and neck of the femoral bone is less than 120 degrees.


Presentation

In patients with coxa vara, the affected hip exhibits a decreased angle between the neck and head of the femoral bone, as a result of a deficient developmental process of the cartilage. The neck of the hipbone may lack in length and its inner medial region may also be subject to fractures. The coxa vara developmental abnormality is closely linked to spondylometaphyseal dysplasia [10] and irregularly formed acetabuli [11], as can be understood from the diversity of the acetabular index and sourcil slope of healthy and affected patients.

Congenital coxa vara is not symptomatic, as the infant is unable to walk and express themselves. Developmental coxa vara is the disease type that emerged early in childhood and causes hip pain and limping, caused by a leg length discrepancy. Acquired coxa vara manifests in the same way as the developmental for of the condition. 

Sepsis
  • Abstract The behavior and treatment of coxa vara and pseudarthrosis of the proximal femur secondary to sepsis is not well described.[ncbi.nlm.nih.gov]
  • Cases journal DOI: 10.4076/1757-1626-2-8130 Coxa vara is an abnormality of the proximal femur with a decreased neck-shaft angle and resulting leg-length discrepancy, has been associated with conditions such as congenital coxa vara, traumatic injury, sepsis[semanticscholar.org]
Coxa Vara
  • Treatment of coxa vara is solely surgical.[symptoma.com]
  • Surgical indications in coxa vara included decreased range of hip motion (usually diminished abduction, extension, and internal rotation), coxa vara with progression documented on regular follow-up hip radiographs, and/or severe coxa vara with a Hilgenreiner[ncbi.nlm.nih.gov]
  • BACKGROUND: Coxa vara is a radiological term describing a decrease in the neck-shaft angle to 120 or less. Coxa vara is associated with pathomechanical changes that can manifest clinically.[ncbi.nlm.nih.gov]
  • These three patients all had developmental coxa vara. The acetabular depth improved significantly in the patients with developmental coxa vara, especially in two patients (three hips) who underwent surgery before 6 years of age.[ncbi.nlm.nih.gov]
  • BACKGROUND: Surgical correction of coxa vara in children with osteopenic bone diseases could be very challenging. In this study, we describe a modified surgical technique for the correction of coxa vara in children with bone fragility.[ncbi.nlm.nih.gov]
Knee Effusion
  • In the knees, effusion was demonstrated in all five patients and thick cartilage in three. The elbow, wrist and ankle joints showed abnormal modeling with evidence or suspicion of intraarticular fluid in the majority of patients.[ncbi.nlm.nih.gov]
Suggestibility
  • CONCLUSIONS: It is suggested that coxa vara predisposes to femoral neck stress-fracture.[ncbi.nlm.nih.gov]
  • This case series suggests an association between neonatal extracorporeal membrane oxygenation and this unusual pattern of coxa vara with proximal femoral growth arrest.[ncbi.nlm.nih.gov]
  • Our studies suggest that the triangular metaphyseal fragment reflects a Salter-Harris type II separation pattern through the defective femoral neck.[ncbi.nlm.nih.gov]
  • He suggested that improper food may have a bearing, which suggests that some of[jamanetwork.com]
Abnormal Gait
  • Early degenerative changes - untreated get severe early OA & often require THR early Symptoms Present at walking age with abnormal gait - painless limp Signs Patient is short with hyperlordosis of spine & waddling gait - limb-length discrepancy - trendelenburg[52.62.202.235]
  • Developmental coxa vara usually occurs as an isolated deformity of the proximal femur and often goes unnoticed until the child reaches walking age and is brought for evaluation of a leg length discrepancy or abnormal gait.[healio.com]
  • It tends to go unnoticed until walking age is reached, when the deformity results in a leg length difference or abnormal gait pattern.[physio-pedia.com]
Unable to Walk
  • Congenital coxa vara is not symptomatic, as the infant is unable to walk and express themselves. Developmental coxa vara is the disease type that emerged early in childhood and causes hip pain and limping, caused by a leg length discrepancy.[symptoma.com]

Workup

The diagnosis of coxa vara requires radiography and, possibly, magnetic resonance imaging (MRI) and a computed tomography (CT) to be diagnosed.

A plain radiograph is an excellent tool to evaluate the positioning of the head and neck of the femur. Coxa vara findings include the angle between these two structures being smaller than 120° and the greater trochanter being uplifted above the head of the femur. The growth plate may also be oriented vertically.

An MRI can be used to better illustrate epiphyseal plates and a CT helps to find out whether there has been any rotation of the hipbone, whether inwards or outwards.

Treatment

Treatment of coxa vara is solely surgical. There is no general agreement amongst the surgical community as to when the procedure should be performed: some surgeons suggest that it should be done as early as possible, as younger patients have better chances to heal properly and acquire a new, fully functional, normal junction. Detractors argue that performing the procedure at a an older age is optimal, since the hipbone will have reached its full potential and will be no longer subject to developmental changes.

Irrespective of the patient's age, surgery is conducted in order to remodel the femoral head/neck intersection. Simultaneously, abductors muscles are repaired, if damaged, and discrepancies in the length between the two legs are also resolved. Children that are younger than 10 years old undergo epiphysiodesis of the greater trochanter. other therapeutic schemes include trochanteric repositioning and Pauwels Y-osteotomy.

Prognosis

All patients with coxa vara caused by trochanteric overgrowth should be closely monitored, since they run a risk of recurrence. Any visible leg length difference should be noted and examined. Patients who undergo appropriate correction with trochanteric repositioning respond well to treatment.

Etiology

Coxa vara may be a developmental abnormality, an acquired, or congenital one. Congenital coxa vara suggests that it arose prior to birth, during the development of the fetus. There is no consensus as to exactly how this deformity is induced; however, various theories have been proposed. The condition is considered a result of increased pressured in the womb due to an abnormal fetal position or caused by some type of bone abnormality that hiders its own growth.

Coxa vara is defined as acquired, when it is generated by another condition or event, such as traumatization of the hip region, of loss of bone continuity (fractures). Developmental coxa vara manifests early in the age of childhood and deteriorates gradually as the young patient grows.

Epidemiology

Pediatric patients exhibit a high risk of developing coxa vara after a fracture of the femoral neck [4]. Data [5] has shown that such fractures, when sustained by young individuals, induce severe complications, such as nonunion, avascular necrosis, shortened extremity, coxa valga, coxa vara and premature epiphyseal fusion. Coxa vara, in particular, accounts for 8% of these complications.

A premature cessation of epiphyseal growth is one of the factors greatly contributing to the development of coxa vara; its incidence has not been accurately calculated, with studies exhibiting rates that fluctuate between 6-62%.

Developmental coxa vara is not frequently observed (incidence estimated at 1:25.000 births) [6].

Sex distribution
Age distribution

Pathophysiology

Histologic data has shown that chondrocytes isolated from hips affected by coxa vara have undergone a deficient developmental process. Their columnar architecture exhibits abnormalities and cartilaginous matrix is calcified [7] [8]. The abnormal cartilage structure does not allow for the full development of the metaphysis and inadvertently causes osteoporotic phenomena and decreased resistance to the forces exerted on that area. The force on the junction between the acetabula and femur causes compression both vertically and horizontally in relation to the physis [9]. A weakened junction tends to bend inwards because it cannot support the aforementioned stress.  

Prevention

Congenital coxa vara cannot be prevented. Acquired forms of the deformity can be anticipated, should a patient be affected by a condition that may cause it, and therefore, proper treatment of the underlying condition will minimize hip abnormality risk. Patients who have sustained hip traumas, or suffer from osteomalacia, deforming arthritis or osteomyelitis, should be closely monitored in order to diagnose coxa vara as early as possible. The earlier an intervention is possible, the better the outcome will be. The distance between the hip joint and the greater trochanter is a useful indicator of coxa vara that can be measured for monitoring causes.

Summary

The degrees of the angle formed between the head and neck of the femoral bone is vital to the structure and functionality of this skeletal component. In children, this is usually a 135° to 145° angle [1]. In cases where the neck and head are positioned in a different way, at a smaller or greater angle, coxa vara and coxa valga [2] result respectively.

Coxa vara involves an angle between these two structures that is reduced to < 120° and is an abnormality of the hipbone's neck. It can be congenital, developmental or a complication of a coexistent disease, like fibrous dysplasia or rickets [3].

The prevailing classification of coxa vara suggests the categorization of the deformity into 2 categories: adolescentium and other forms. Under the category of other forms falls any other occurrence due to the following reasons:

Therefore, there are two distinct coxa vara forms. False coxa vara is associated with an underlying condition, which causes inflammation or trauma to the neck of the femoral bone, thus altering the anatomy of its angle. The other type, true coxa vara, arises from lesions that are not inflammatory and render the hipbone's neck to be unable to resist the weight and other types of forces exerted on it. True coxa vara is frequently observed amongst the adolescent population. In children affected by skeletal dysplasia, coxa vara tends to be an escalating condition.

Patient Information

In order to understand the definition of coxa vara, one should be familiar with the anatomy of the hip joint. the hip joint is the connection between the top part of the femoral bone (or thighbone) and the pelvic region. The top part of the thighbone is called the "head" and the part of the longer bone immediately below it is the neck. the head and neck form a horizontal angle with each other.

Coxa vara is an abnormal formation of this angle, which is less than 120°. This is a result of defective development of the bone and causes hip pain and a difference in the length of the two legs and subsequent limping.

An individual may be affected with coxa vara since birth; this constitutes the congenital type. Developmental coxa vara means that a patient was not born with it, but it was a result of abnormal development. This is usually to be seen early in childhood, as the individual first starts to walk. Coxa vara can also be a complication of another condition, usually one that affects the bones, like osteomyelitis or bone fracture, with this being the third type, acquired coxa vara. In general, the condition is rare, as it is observed at a rate of 1 in 13,000-25,000 live births.

Both men and women are affected equally. Coxa vara may be present in one joint or both. Patients experiencing hip pain and movement restriction should always visit their physician, who is responsible for evaluating the hip status. Coxa vara is most of the times diagnosed in young ages, due to hip pain and limping, but older patients can be affected with the acquired deformity type. A plain x-ray , an MRI or CT scan will help the physician diagnose the hip condition. in cases of coxa vara, treatment is exclusively surgical, as the condition does not resolve on its own.

References

Article

  1. Lam F, Hussain S, Sinha J. Emerg Med J. An unusual cause of a limp in a child: developmental coxa vara. Emerg Med J. 2001 Jul;18(4):314.
  2. Clohisy JC, Nunley RM, Carlisle JC, Schoenecker PL.Incidence and Characteristics of Femoral Deformities in the Dysplastic Hip. Clin Orthop Relat Res. 2009; 467(1): 128–134.
  3. DiFazio R, Kocher M, Berven S, Kasser J. Coxa vara with proximal femoral growth arrest in patients who had neonatal extracorporeal membrane oxygenation. J Pediatr Orthop 2003; 23: 20-26.
  4. Eberl R, Singer G, Ferlic P, Weinberg AM, Hoellwarth ME. Post – traumatic coxa vara in children following screw fixation of the femoral neck. Acta Orthop. 2010 Aug;81(4):442-5.
  5. Togrul E, Bayram H, Gulsen M, Kalaci A, Ozbarlas S. Fractures of the femoral neck in children: long-term follow-up in 62 hip fractures. Injury. 2005 Jan;36(1):123-30.
  6. Lam F, Hussain S, Sinha J. An unusual cause of a limp in a child: developmental coxa vara. Emerg Med J. 2001 Jul;18(4):314.
  7. Chung SM, Riser WH. The histological characteristics of congenital coxa vara: a case report of a five year old boy. Clin Orthop. 1978 May; (132):71-81. 
  8. Bos CF, Sakkers RJ, Bloem JL, et al. Histological, biochemical, and MRI studies of the growth plate in congenital coxa vara. J Pediatr Orthop. 1989 Nov-Dec; 9(6):660-5. 
  9. Ranade A, McCarthy JJ, Davidson RS. Acetabular changes in coxa vara. Clin Orthop Relat Res. 2008 Jul; 466(7):1688-91
  10. Currarino G, Birch JG, Herring JA. Developmental coxa vara associated with spondylometaphyseal dysplasia (DCV/SMD): "SMD-corner fracture type" (DCV/SMD-CF) demonstrated in most reported cases. Pediatr Radiol. 2000 Jan;30(1):14-24.
  11. Ranade A, McCarthy JJ, Davidson RS. Acetabular changes in coxa vara. Clin Orthop Relat Res. 2008 Jul;466(7):1688-91.

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Last updated: 2019-07-11 22:42