Subtrochanteric Shortening Osteotomy Provides Superior Function to Trochanter Slide Osteotomy in THA for Patients With Unilateral Crowe Type IV Dysplasia at a Minimum of 3 Years
Authors: Ravanbod Hadi , Gharanizadeh Kaveh , Mirghaderi Peyman , Hassan Ahmad , Abolghasemian Mansour 
Published: October 2023

Abstract

Background
Performing THA in patients with high-riding developmental dysplasia of the hip (DDH) is associated with serious complications and technical challenges. Various methods of shortening osteotomy are available to facilitate femoral head reduction during THA in patients with high-riding hips; subtrochanteric shortening osteotomy and trochanteric slide osteotomy plus proximal shortening are the most common techniques. However, which approach is superior remains a topic of controversy.

Questions/purposes
(1) Is there any difference in clinical outcomes (defined as the Harris Hip Score [HHS] and residual limb length discrepancy) at a minimum of 3 years between subtrochanteric shortening osteotomy and trochanteric slide osteotomy in patients with Crowe Type IV DDH who underwent THA? (2) Is there any difference in the risk or type of complications between the two approaches?

Methods
We performed a retrospective, comparative study of two groups (subtrochanteric shortening osteotomy versus trochanteric slide osteotomy) matched for sex and preoperative HHS at a minimum of 3 years of follow-up. Between 2010 and 2018, we performed 67 THAs in patients with unilateral Crowe Type IV DDH. During that time, we generally used a trochanteric slide osteotomy for THA in all patients with Crowe Type IV hips and performed subtrochanteric shortening osteotomy when a conical stem was not available. A total of 42% (28) had THA with subtrochanteric shortening osteotomy, and 58% (39) had THA with trochanteric slide osteotomy. Of those, 89% (25) and 74% (29), respectively, were accounted for with complete datasets for possible matching at a minimum of 3 years of follow-up. Patients were matched for gender and preoperative HSS (within 10 points), leaving 22 patients in each group (79% of the subtrochanteric shortening osteotomy group and 56% of the trochanteric slide osteotomy group) for evaluation and analysis. Age (42 versus 46 years), gender (female: 73% versus 73%), preoperative HSS (40 versus 40), and preoperative leg length discrepancy (5.9 versus 5.3 cm) were comparable between the two groups (p > 0.05). The trochanteric slide osteotomy group exclusively received Cone Wagner (Zimmer) implants (100%), while Corail (DePuy Synthes) implants (77%) were the most commonly used in the subtrochanteric shortening osteotomy group. HHS at a minimum of 3 years as well as the presence or absence of a limp and Trendelenburg sign, functional leg length discrepancy, nonunion, nerve palsy, and other surgical complications were recorded and compared between the groups based on data drawn from a longitudinally maintained institutional database.

Results
At a mean follow-up of 73 months, improvement in HHS was greater in the subtrochanteric shortening osteotomy group than in the trochanteric slide osteotomy group (48 ± 4 points versus 36 ± 11 points, mean difference 12 points [95% CI 7 to 17 points]; p < 0.001). Although the preoperative leg length discrepancy was similar between the groups, there was a greater postoperative improvement in the subtrochanteric shortening osteotomy group (44 ± 8 mm and 38 ± 8 mm in the subtrochanteric shortening osteotomy and trochanteric slide osteotomy groups, respectively; p = 0.02). The risk of nonunion was higher with a trochanteric slide osteotomy than with a subtrochanteric shortening osteotomy (23% [5 of 22] versus 0% [0 of 22]; p = 0.048). Other complications, including intraoperative periprosthetic fractures, nerve palsy, heterotopic ossification, revision surgery, and dislocation, did not differ between the groups.

Conclusion
In patients with Crowe Type IV hips undergoing THA, surgeons might consider subtrochanteric shortening osteotomy rather than trochanteric slide osteotomy to minimize the risk of nonunion and achieve superior hip function. Better correction of leg length discrepancy may also be possible with subtrochanteric shortening osteotomy. The long-term survivorship of hips after these two techniques, as well as the influence of the specific anatomy of the proximal femur on the choice of technique, remain to be explored in future studies.

Level of Evidence
Level III, therapeutic study.