Direct Anterior Approach Reduces Dislocation Risk in Head and Liner Exchange

Mitigating Instability in Modular Revision Hip Arthroplasty

Isolated head and liner exchange (a procedure where only the modular components are replaced while well-fixed acetabular and femoral stems are retained) serves as a less invasive revision strategy for patients with polyethylene wear, offering reduced surgical morbidity and faster recovery compared to full component revision [1]. However, postoperative instability remains the most frequent complication, often necessitating the use of larger femoral heads, elevated liners, or dual mobility constructs (implants featuring a second mobile bearing surface to increase the jump distance) to maintain joint integrity [2, 3]. While these specialized implants can reduce dislocation risk, they may also introduce concerns regarding long-term wear debris or mechanical failure [4, 5]. The choice of surgical approach in the revision setting is increasingly scrutinized, as surgeons seek techniques that preserve soft tissue tension and optimize component orientation, particularly because acetabular cups with more than 48 degrees of abduction are 2.6 times more likely to dislocate [6]. A recent retrospective study of 176 cases now evaluates how the direct anterior approach (a muscle-sparing technique that accesses the joint through the interval between the tensor fasciae latae and the sartorius) compares to traditional methods in preventing these early mechanical failures [3].

Comparing Surgical Approaches in Polyethylene Wear Revision

The researchers conducted a retrospective review of 176 cases involving isolated head and liner exchange performed specifically to address polyethylene wear between 2016 and 2025. To ensure the findings focused on new-onset instability rather than pre-existing complications, the authors applied strict exclusion criteria, removing any cases with a history of previous periprosthetic joint infection (a bacterial colonization of the prosthetic components and surrounding tissue) or a documented history of previous instability. By removing these confounding variables, the study aimed to isolate the impact of the surgical approach on postoperative outcomes. The total cohort was divided into two groups: 129 cases were performed using the postero-lateral approach, while 47 cases utilized the direct anterior approach. To compare these groups, the researchers utilized Cox proportional hazards regressions (a statistical method used to determine the time until a specific event, such as a dislocation or a reoperation, occurs). This analysis allowed the team to calculate the relative risk of these complications over time. The primary objective was to determine if the direct anterior approach resulted in a lower incidence of dislocation when compared to the postero-lateral approach for isolated head and liner exchange.

Disparity in the Use of Instability-Mitigating Implants

The researchers observed a marked difference in the intraoperative strategies employed to stabilize the hip joint between the two surgical cohorts. In the postero-lateral approach group, surgeons more frequently utilized aggressive implant modifications to counteract the risk of postoperative instability. Specifically, femoral head diameter was increased in 74.1% of the postero-lateral approach cohort, whereas this modification was necessary in only 32.4% of the direct anterior approach cohort. This disparity suggests that the direct anterior approach may provide inherent stability that reduces the perceived need for larger femoral heads, which are typically used to increase the jump distance (the distance the femoral head must travel to escape the acetabular socket). Further analysis of the component selection revealed that specialized, instability-mitigating liners were disproportionately required during postero-lateral approach procedures. Elevated liners were placed in 45.7% of the postero-lateral approach cases, a sharp contrast to the 6.4% of cases in the direct anterior approach group. Furthermore, the postero-lateral approach cohort required the use of highly specialized constructs to ensure joint integrity, including dual mobility constructs in 6.9% of cases and constrained liners in 4.7% of cases. In a notable finding, neither dual mobility constructs nor constrained liners were used in any cases (0%) of the direct anterior approach cohort. These data indicate that the direct anterior approach achieved superior stability outcomes despite a significantly lower reliance on specialized hardware designed to prevent dislocation, which may reduce the risk of long-term mechanical complications associated with constrained components.

Eight-Fold Reduction in One-Year Dislocation Rates

The primary clinical outcome of the study demonstrated a substantial difference in joint stability between the two surgical cohorts at the twelve-month mark. At one year, the dislocation incidence was 2.4% after the direct anterior approach, a figure that stands in stark contrast to the 12.4% dislocation incidence observed after the postero-lateral approach. Statistical analysis confirmed that the direct anterior approach provided significantly higher dislocation-free survivorship (log-rank Chi-square = 5.55, P = 0.02). When adjusting for variables, the researchers found that the hazard ratio for dislocation in the postero-lateral approach versus the direct anterior approach was 7.68 (P = 0.04). This indicates that the use of the direct anterior approach for isolated head and liner exchange was associated with a nearly eight-fold lower risk of dislocation compared to the postero-lateral approach. Secondary endpoints regarding surgical durability also favored the direct anterior approach, though the differences in these metrics did not reach the same level of statistical significance. The one-year reoperation incidence was 2.7% after the direct anterior approach, while the one-year reoperation incidence was 6.2% after the postero-lateral approach. Despite the lower absolute rate of return to the operating room for the direct anterior group, there was no significant difference in reoperation-free survivorship between groups (log-rank Chi-square = 1.64, P = 0.20). The hazard ratio for reoperation was 2.54 (P = 0.22), suggesting that while the direct anterior approach may reduce instability-related complications, other factors contributing to reoperation remained comparable between the two techniques. These findings suggest that the direct anterior approach may offer inherent mechanical stability during head and liner exchange, potentially allowing clinicians to achieve better outcomes with less complex implant configurations and lower risk of postoperative instability.

References

1. Stafeev DV, Spetsialnyi DV, Lyakh AR, Iev NV, Denisov A, Tikhilov R. Isolated Head and Liner Exchange for Polyethylene Wear and Periprosthetic Osteolysis in Revision Hip Arthroplasty: A Review. 2025. doi:10.17816/2311-2905-17747

2. Faldini C, Stefanini N, Fenga D, et al. How to prevent dislocation after revision total hip arthroplasty: a systematic review of the risk factors and a focus on treatment options. Journal of Orthopaedics and Traumatology. 2018. doi:10.1186/s10195-018-0510-2

3. Gausden EB, Afzal S, Bhatti P, et al. Instability Following Head and Liner Exchange: 8-Fold Reduction in Dislocation with the Direct Anterior Approach.. The Journal of arthroplasty. 2026. doi:10.1016/j.arth.2026.04.040

4. Traina F, Fine MD, Martino AD, Faldini C. Fracture of Ceramic Bearing Surfaces following Total Hip Replacement: A Systematic Review. BioMed Research International. 2013. doi:10.1155/2013/157247

5. Soliman MM, Chowdhury MEH, Islam MT, et al. A Review of Biomaterials and Associated Performance Metrics Analysis in Pre-Clinical Finite Element Model and in Implementation Stages for Total Hip Implant System. Polymers. 2022. doi:10.3390/polym14204308

6. Robertson RN, Parks NL, Ho H, Hopper RH, Hamilton WG. Does Approach Influence the Dislocation Rate Following Head and Liner Exchange in Revision Hip Arthroplasty?. The Journal of arthroplasty. 2022. doi:10.1016/j.arth.2021.10.005