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Single-stage surgical correction of a bilateral acquired coxa vara deformity in a young woman
  1. Aabid Husain Ansari1,
  2. Amit Kumar Gupta2,
  3. Abhishek Vaish1 and
  4. Raju Vaishya2
  1. 1Orthopedics, Indraprastha Apollo Hospital, New Delhi, India
  2. 2Orthopaedics and Joint Replacement Surgery, Indraprastha Apollo Hospital, New Delhi, India
  1. Correspondence to Dr Aabid Husain Ansari; aabidhusain25{at}gmail.com

Abstract

A 23-year-old female-treated patient of osteomalacia and secondary hyperparathyroidism with hypophosphatemia presented with a 5-year history of bilateral groin pain and stiffness of both hips and difficulty in walking. Plain radiographs of the pelvis showed bilateral coxa vara deformity. She was managed surgically by a single-stage bilateral subtrochanteric corrective osteotomy with the internal fixation. After the osteotomy healing at 3 months, the patient was pain free and walked comfortably with an increased range of hip motion.

  • metabolic disorders
  • joint interposition
  • medical education

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Background

Acquired coxa vara deformity is uncommon in adults. Metabolic causes like osteomalacia (due to vitamin D deficiency) are an essential cause of it.1 2 This deformity causes severe disability and locomotion difficulties in the affected individual. If this deformity is not corrected, the pelvic deformity, restricted range of motion and secondary hip osteoarthritis often ensue. Coxa vara is correctible if diagnosed and managed in time. We present a case of young woman with bilateral coxa vara due to previously treated osteomalacia. She was managed surgically by a single-stage bilateral subtrochanteric corrective osteotomy with the internal fixation.

Case presentation

A 23-year-old woman was presented with bilateral groin pain and stiffness of both hips for 5 years and difficulty in walking. She denied any trauma or morning stiffness. One year ago, she was diagnosed with osteomalacia and secondary hyperparathyroidism with hypophosphatemia and treated conservatively (with calcium, vitamin D, bisphosphonates and a high protein diet) for severe vitamin D deficiency with multiple insufficiency fractures in both proximal femora and pelvis.3 After 1 year of the conservative treatment, she presented for the above-mentioned complaints. She was short statured (height–132 cm) and obese (weight–62 kg) with a body mass index of 35.6 kg/m2. Examination revealed painfully restricted range of motions of both hips, with abduction from 0° to 10° only, on both sides.

Investigations

Anteroposterior view of the pelvis with both hips showed bilateral coxa vara deformity with the neck-shaft angle of 110° on left side and 98° on right side (figure 1).

Figure 1

Preoperative plain radiograph (anteroposterior view) of the hips, showing healed fractures with bilateral coxa-vara deformity.

After successfully conservative treatment, all laboratory parameters became normal; serum alkaline phosphatase (145 U/L), serum parathyroid hormone (20.2 pg/mL), serum calcium (9.6 mg/dL), serum phosphorus (4.1 mg/dL) and 25-hydroxyvitamin D (220 nmol/L).

Differential diagnosis

The coxa vara deformity could be due to congenital, developmental and acquired causes. The congenital and developmental conditions include spondyloepiphyseal dysplasia, cleidocranial dyostosis, multiple epiphysial dysplasia, metaphyseal dysostosis. The acquired causes are due to trauma, Avascular Necrosis of the femoral head (eg, developmental dysplasia of the hip, Perthes’ disease), fibrous dysplasia, slipped capital femoral epiphysis, rickets, osteomalacia, osteoporosis, osteogenesis imperfecta, osteomyelitis of hip, tuberculosis of the hip, septic arthritis and Paget’s disease.

Treatment

After healing of all insufficiency pelvic fractures, she was managed with a single-stage corrective valgus subtrochanteric osteotomy (closed wedge). Since the patient was a dwarf, she could not be positioned on an adult fracture table for the surgery. Hence, the procedures were done sequentially in the lateral decubitus position. Osteotomy was fixed with 95° dynamic condylar screw (DCS) and plate.

Outcome and follow-up

Postoperatively, the neck-shaft angle was improved (121° on the left hip and 115° on the right hip). The patient was mobilised in a wheelchair for 1 month, followed by mobilisation with a walking frame for another 1 month, and then full weight-bearing was allowed. At 3 months follow-up after surgery, she was clinically pain free, able to mobilise without support, and osteotomy was completely healed. At 1-year follow-up, there was an increase in the range of hip abduction motion of both hip joints, 35° on the left side and 32° on the right side (figures 2 and 3). She had no limb length discrepancy or gait abnormality.

Figure 2

Postoperative plain radiograph (anteroposterior view) of the hips at 1-year follow-up, showing healed osteotomy with increased neck-shaft angle.

Figure 3

Postoperative clinical photograph at 1-year follow-up, showing increased hip abduction motion of both hip joints.

Discussion

Coxa vara is a hip deformity, in which the femoral neck-shaft angle is reduced to less than 120° angle. Coxa vara deformity could be due to a developmental, congenital or traumatic causes. Acquired types are uncommon and occurs due to metabolic causes, infective causes, fibrous dysplasia, trauma, etc.1 2 4 Coxa vara can produce a focal concentration of stresses in the femoral neck and may cause stress fractures of femoral neck.5 Osteomalacia is one of the most common metabolic causes of acquired coxa vara, which is often associated with insufficiency fractures in the femoral neck and pelvis. Osteomalacia occurs due to defective bone mineralisation, which leads to softening of bone and may cause bone pain, weakness, pathological fracture and deformity. Hip is one of the common sites of an insufficiency fracture, which may lead to coxa vara deformity of the hips.6 7

There are no clear guidelines in the existing literature about the management protocol of coxa vara, but the surgical management is the most accepted treatment method for this condition.2 The indications for surgical correction are (a) progressive deformity or significant gait abnormality, (b) a vertically oriented physeal plate, (c) Hilgreiner’s epiphysial angle of more than 60° and the neck-shaft angle less than 90° to 100°.8 The corrective valgus osteotomy improves the gluteus muscle’s action, normalising the femur neck-shaft angle, increasing the limb length and improving the hip joint movements and its congruency (figure 4).4

Figure 4

The corrective valgus osteotomy improves the neck-shaft angle.

In coxa vara deformity, the hip’s biomechanics are altered as the tip of the greater trochanter is elevated and abductor muscle length is shortened. Therefore, the position and direction of muscular force M are changed. There is an increase in the shearing forces, resulting from the compressive force R, which diverges more than normal. The hip’s biomechanics are improved with corrective valgus osteotomy, by lengthening the lever arm of the abductor muscles, and, thus, creating more horizontal orientation of force M. It results in a decrease in the resultant force R, that is displaced medially over a larger surface, resulting into smaller compressive stress on the joint.9

The acquired non-traumatic coxa vara is a rare condition, and not much has been mentioned about its surgical management details in the present literature. On the contrary, there is a good literature available on the deformity correction in congenital and dysplastic types of coxa vara by pelvic and femoral osteotomies.10 In this case of acquired coxa vara, since there was no pelvic deformity, the neck-shaft angle was the sole criterion for correction of the deformity. A closed-wedge sub trochanteric osteotomy seemed the most suitable surgical option to correct these deformities. Detailed preoperative planning is required on the radiographs, in the form of level of osteotomy, the amount of wedge removal and the choice and placement of implants to fix the osteotomy. 3-D printing has been found useful in virtual preoperative planning to correct such deformities, but it is not universally available.11 12 We chose to do the bilateral correction of deformity as a single-stage procedure. The valgus osteotomy in adults needs fixation with a suitable implant like DCS and plate, dynamic hip screw (DCS) and plate, 95° angled blade plate. We preferred to use the 95° angled DCS, with good fixation and outcomes, and would, therefore, recommend its use to fix such an osteotomy (figure 5). There was an increase in the range of hip abduction motion of both hip joints, 35° on the left side and 32° on the right side, with an increase in the neck-shaft angles. We observed significant improvement in the clinical outcomes of this case, making her life much more comfortable.

Figure 5

Schematic showing good correction in neck-shaft angle after subtrochanteric valgus osteotomy and fixation with 95° dynamic condylar screw and a barrel plate.

Patient’s perspective

I am extremely happy with the outcome of my treatment. One year ago, I could not even walk, but after the medical and surgical treatment, I am not only able to walk pain free but also have significant improvement in the movements of my hips. This has helped me to do my activities of daily living independently.

Learning points

  • Acquired coxa vara could occur due to osteomalacia, other than the non-traumatic and non-developmental disorders.

  • This hip deformity causes severe disability and locomotion difficulties.

  • If not corrected, pelvic deformity, restricted range of motion and secondary hip osteoarthritis often ensue.

  • A corrective subtrochanteric femoral valgus osteotomy, with internal fixation, increases the hip joints’ range of motion and prevents secondary hip arthritis.

Ethics statements

Patient consent for publication

References

Footnotes

  • Contributors AHA: main manuscript preparation. AKG: collected data. AV: critically reviewed the study proposal. RV: provided study patient, illustrated figures 4 and 5.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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