Abstract
BackgroundWhen reconstructing a hip with developmental dysplasia and high dislocation, sub-trochanteric shortening osteotomy is typically needed for placing the acetabular component in the appropriate anatomical position. However, the procedure can result in complications such as non-union of the osteotomy. We evaluated the contact area and the coincidence rate between the proximal and distal fragments at different femoral osteotomy levels and lengths. We then determined the optimal location of subtrochanteric femoral shortening transverse osteotomy in patients with unilateral Crowe type IV developmental dysplasia of the hip (DDH). The consistency between the proximal and distal segments was assessed as a possible predictive indicator of the union at the osteotomy site.MethodsWe retrospectively reviewed 57 patients with unilateral Crowe type IV DDH who underwent X-ray imaging of both hip joints. We labelled the inner and outer diameters of the circular ring as N (mm) and M (mm), respectively. We defined the overlapped area between the proximal and distal ring as contact area S (mm2), and the ratio of contact area to distal ring area as coincidence rate R.ResultsN varied from 9.8–15.2 mm and M varied from 20.7–24 mm, both demonstrated a decreasing trend in the proximal to distal direction. At osteotomy lengths ranging from 0.5–2 cm, there were no differences in S between the different levels of osteotomy in each group. At osteotomy lengths ≤2.5 cm, a significant higher coincidence rate was noted from 2 cm below the lesser trochanter to other positions below the level. At osteotomy lengths from 3 to 5.5 cm, a significantly higher coincidence rate was observed from the level of 1.5 cm below the lesser trochanter to other positions below the level.ConclusionsOur findings suggest that femoral shortening transverse osteotomy at the optimal subtrochanteric level can predictably increase the contact area and coincidence rate, which may contribute to the union at the osteotomy site. Considering the stability of the prostheses, it appears appropriate that osteotomy location should be shifted slightly distally.Trial registrationRetrospectively registered.
Highlights
When reconstructing a hip with developmental dysplasia and high dislocation, sub-trochanteric shortening osteotomy is typically needed for placing the acetabular component in the appropriate anatomical position
A limited bone contact area is a major disadvantage of transverse osteotomy, which may interfere with the bone healing process [18, 19]
In order to assess the consistency between the proximal and distal segments as a potential predictive indicator of the union of the osteotomy site, we evaluated the contact area and coincidence rate between the proximal and distal fragments at different levels and lengths of femoral osteotomy
Summary
When reconstructing a hip with developmental dysplasia and high dislocation, sub-trochanteric shortening osteotomy is typically needed for placing the acetabular component in the appropriate anatomical position. We determined the optimal location of subtrochanteric femoral shortening transverse osteotomy in patients with unilateral Crowe type IV developmental dysplasia of the hip (DDH). The consistency between the proximal and distal segments was assessed as a possible predictive indicator of the union at the osteotomy site. Performing THA in Crowe type IV developmental dysplasia of the hip (DDH) is technically demanding and does present many challenges to the surgeon in terms of both the femoral and acetabular sides. Subtrochanteric femoral shortening osteotomy was introduced to facilitate pulling down of the femur, correct the rotational abnormalities, preserve the proximal femoral metaphysis, and reduce the risk of nerve injury [6]. The consistency of the interfaces and canal diameters between the proximal and distal segments may contribute to union; the two osteotomy interfaces should be as smooth as possible to maintain their intactness [20]
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