Total Hip Arthroplasty Using a Direct Anterior Approach Reduces Postoperative Leg Length Differences by Preserving the Medial Iliofemoral Ligament

Abstract

Background: This study compared postoperative leg length discrepancy (LLD) and global hip offset (GO) between medial iliofemoral ligament preservation and excision during total hip arthroplasty (THA) using direct anterior approach.

Methods: A retrospective review of 101 unilateral THA cases performed between January 2022 and July 2024 divided patients into 2 groups: ligament excision and ligament preservation groups. The medial iliofemoral ligament was excised from January 2022 to August 2023 and preserved from September 2023 to July 2024. The final leg length was determined based on intraoperative confirmation of THA stability. Preoperative and postoperative radiographs were analyzed to measure LLD and GO. The percentage of cases with absolute postoperative LLD and GO contralateral differences >5 mm was examined in both groups. To minimize the influence of implants, such as large diameter heads, only THA head diameters of 28 or 32 mm were used. Clinical complications within 3 months postsurgery were also examined.

Results: The preservation group exhibited significantly smaller postoperative LLD and absolute LLD than the excision group (P < .01), with fewer patients experiencing postoperative LLD >5 mm (P < .01). GO did not differ between the groups. Clinical complications included one dislocation, 2 fractures, and one infection in the excision group, while the preservation group had one fracture. No significant difference in complication rates was found.

Conclusions: Medial iliofemoral ligament preservation during THA using direct anterior approach effectively reduces postoperative LLD without increasing complications or compromising GO.

Keywords: Direct anterior approach; Leg length discrepancy; Preserving the medial iliofemoral ligament; Total hip arthroplasty.

Figure 1

The technique for manipulating the iliofemoral ligament; solid line, excision; dotted line, preservation.

Figure 2

The medial iliofemoral ligament remained intact during closure in the preservation group. (∗): Medial iliofemoral ligament.

Figure 3

Anteroposterior pelvic and femoral radiographs. (a) LLD was the left–right difference between the line connecting the tear drop and the top of the small trochanter and (b) GO was the sum of the distance from the pubic symphysis to the center of the femoral head and the distance from the femoral head to the femoral axis.