Optimal location of subtrochanteric osteotomy in total hip arthroplasty for crowe type IV developmental dysplasia of hip

Abstract

Background: 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. 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. Methods: We 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 (mm 2), and the ratio of contact area to distal ring area as coincidence rate R. Results: N 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. Conclusions: Our 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 registration: Retrospectively registered.

Finite Element Analysis of Optimal Positioning of Femoral Osteotomy in Total Hip Arthroplasty With Subtrochanteric Shortening

“…On the other hand, Huang et al. determined the optimal osteotomy position by evaluating the contact area and coincidence rate between the proximal and distal fragments [ 13 ] and demonstrated that a level 1 cm below the lesser trochanter was optimal. Their conclusions support the findings of the present study.…”

“…However, the possibility of rotational deviation of the stem in the early postoperative period presents a challenge for surgeons. Although one report determined the optimal osteotomy position by evaluating the contact area and coincidence rate between the proximal and distal fragments [ 13 ], no previous study has demonstrated the mechanical effects on the stem and bone. Because femoral osteotomy positioning is an important factor influencing the rotational deviation, the aim of the present study was to use finite element analysis (FEA) to determine the optimal position for osteotomy in THA with an Exeter cemented stem under conditions of full weight-bearing and turning torque.…”

Mid‐Term Outcomes of Cemented Stem and Subtrochanteric Shortening Derotational Osteotomy in Total Hip Arthroplasty for Crowe IV Developmental Dysplasia

“…Nonunion at the osteotomy site may lead to varus angulation, pain, loss of rotational stability, and prosthetic loosening 7,34 . Proper union of the osteotomy site depends on several factors, including the stability of the osteotomy site, 35 size of the contact area between the proximal and distal segments, 22 available bone stock, and degree of vascularization. Among these factors, the stability of the osteotomy site is the most important and is contingent on the osteotomy type, stem fixation method, stem morphology, and use of additional fixation materials such as cables or plate and screws 34,36 .…”

“…Bone union at the osteotomy site was assessed using postoperative radiographs based on the criteria for bone union described by Masonis et al [8]. The level of the osteotomy site was measured according to a report published in 2020 [24]. The length of the cemented stem bridging the osteotomy site was also noted.…”

“…If the femoral head was not reduced into the acetabulum, the distance between the top of the acetabular implant and the femoral head need to be measured. According to Huang et al [24], initial osteotomy was performed at an optimal level below the lesser trochanter (the mean level of the initial osteotomy site was 21.1 mm [range, 15-30 mm]). The trial stem was then inserted into the proximal fragment, and the trial head was reduced into the cup.…”