A person confidently walks a path of interconnected hip implants, symbolizing a successful hip replacement journey.

Hip Replacement Hiccups? Navigating Dislocation Risks After Femoral Neck Fracture

Author's portrait.
Elliot Brynn in Health & Wellness November 2025 • 4 min read.

"Modern hip implants offer improved stability, but is dislocation risk truly minimized? Unpacking the concerns around total hip arthroplasty and displaced femoral neck fractures."


Hip replacement surgery, or total hip arthroplasty (THA), is a common and often highly successful procedure for relieving pain and restoring mobility in individuals with damaged hip joints. However, like any surgical intervention, it carries potential risks and complications. One of the primary concerns following THA, particularly when performed to address a displaced femoral neck fracture (DFNF), is the risk of hip dislocation.

A recent study published in the Journal of Clinical Orthopaedics and Trauma (2017) investigated the incidence of hip dislocation following THA for DFNF and aimed to identify associated risk factors. While modern implants have been designed to improve stability and reduce the likelihood of dislocation, questions remain about their effectiveness in all cases. This article explores two critical queries raised regarding the aforementioned study, shedding light on potential limitations and areas for further investigation. We'll help you understand the nuances of THA, the factors influencing dislocation risk, and how to approach recovery with confidence.

Understanding these concerns can empower patients to have informed conversations with their surgeons, actively participate in their rehabilitation, and ultimately improve their chances of a successful outcome. Whether you're considering THA, recovering from the procedure, or simply seeking to learn more, this guide provides valuable insights into navigating the complexities of hip replacement and minimizing dislocation risks.

The Dislocation Dilemma: Examining the Evidence

A person confidently walks a path of interconnected hip implants, symbolizing a successful hip replacement journey.

One of the central points of contention revolves around the interpretation of data related to acetabular cup placement. The original study reported that a significant proportion of acetabular cups (47%) were positioned outside the Lewinnek safe zone, a commonly used guideline for optimal cup placement. While the study found a higher dislocation rate in THAs with cups outside this zone (12.5% vs. 0%), the difference wasn't statistically significant.

This lack of statistical significance led the authors to suggest that placement outside the safe zone might not be a significant risk factor for dislocation. However, this conclusion seems at odds with the widely held belief that optimal cup positioning is crucial for hip stability. The safe zone is designed to provide a balance between range of motion and joint stability, and deviations from this zone could potentially increase the risk of impingement or instability, leading to dislocation.

  • Safe Zone Defined: The Lewinnek safe zone aims to optimize hip joint stability.
  • Statistical Significance: Lack of significance in original study raises questions.
  • Conflicting Views: Experts believe optimal cup position minimizes dislocation risk.
  • Impingement and Instability: Deviations may lead to these issues, increasing dislocation risk.
The debate underscores the complexities of THA and the need for careful consideration of individual patient factors. While the Lewinnek safe zone provides a useful guideline, it's not a one-size-fits-all solution. Surgeons must take into account a patient's anatomy, activity level, and other individual characteristics when determining the optimal cup position. Further research is needed to refine our understanding of the relationship between cup placement and dislocation risk, and to develop more personalized approaches to THA.

Moving Forward: A Call for More Data

Ultimately, addressing the concerns surrounding dislocation risk after THA requires a commitment to ongoing research and data collection. Larger, well-designed studies are needed to evaluate the impact of acetabular cup position, surgical technique, implant design, and patient-specific factors on dislocation rates. By gathering more comprehensive data and refining our understanding of the biomechanics of the hip joint, we can continue to improve the outcomes of THA and minimize the risk of this debilitating complication. In the meantime, maintain open communication with your healthcare team. Discuss any concerns you have, actively participate in your rehabilitation program, and follow their guidance closely to optimize your recovery and reduce your risk of dislocation.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.jcot.2018.11.003, Alternate LINK

Title: Two Queries On M. Noticewala Et Al.: Has The Risk Of Dislocation After Total Hip Arthroplasty Performed For Displaced Femoral Neck Fracture Improved With Modern Implants?

Subject: Orthopedics and Sports Medicine

Journal: Journal of Clinical Orthopaedics and Trauma

Publisher: Elsevier BV

Authors: Fei Wu, Gang Liu

Published: 2019-07-01

Everything You Need To Know

1

What is total hip arthroplasty (THA) and why is hip dislocation a concern after this procedure?

Total hip arthroplasty (THA) is a surgical procedure designed to relieve pain and restore mobility in individuals with damaged hip joints. It involves replacing the damaged joint with artificial implants. While generally successful, one significant concern, especially following a displaced femoral neck fracture (DFNF), is the potential for hip dislocation.

2

What is the Lewinnek safe zone and why is it relevant in total hip arthroplasty (THA)?

The Lewinnek safe zone is a commonly used guideline for acetabular cup placement during total hip arthroplasty (THA). It represents a range of angles for cup positioning intended to optimize hip joint stability and range of motion. Placing the cup outside this zone may increase the risk of impingement or instability, potentially leading to dislocation, although some studies show conflicting evidence.

3

What did the study in the *Journal of Clinical Orthopaedics and Trauma* (2017) reveal about hip dislocation after total hip arthroplasty (THA) for displaced femoral neck fractures (DFNF)?

A study in the *Journal of Clinical Orthopaedics and Trauma* (2017) investigated hip dislocation rates after total hip arthroplasty (THA) for displaced femoral neck fractures (DFNF). It found that a large percentage of acetabular cups were placed outside the Lewinnek safe zone, but the increased dislocation rate in those cases wasn't statistically significant. This raises questions about the absolute importance of strict adherence to the safe zone.

4

If the study showed no statistically significant increase in dislocation when the acetabular cup is outside the Lewinnek safe zone, why are experts still concerned about optimal cup positioning during total hip arthroplasty (THA)?

While the study mentioned found no statistically significant difference in dislocation rates when acetabular cups were placed outside the Lewinnek safe zone, many experts still believe optimal cup positioning is crucial for hip stability. Deviations from the Lewinnek safe zone could lead to impingement or instability, increasing the risk of dislocation. It's important to consider that the Lewinnek safe zone is a guideline, and surgeons must also consider individual patient anatomy, activity level, and other factors to determine the optimal cup position.

5

What steps can be taken to minimize the risk of hip dislocation following total hip arthroplasty (THA)?

Minimizing dislocation risk after total hip arthroplasty (THA) involves several key strategies. Patients need to actively participate in their rehabilitation program, closely follow their healthcare team's guidance, and maintain open communication. Surgeons should carefully assess individual patient factors when determining acetabular cup placement, considering that the Lewinnek safe zone is a guideline, not an absolute rule. Furthermore, ongoing research is crucial to refine our understanding of the biomechanics of the hip joint and develop more personalized approaches to THA, accounting for surgical technique, implant design, and patient-specific factors.

Newsletter Subscribe

Subscribe to get the latest articles and insights directly in your inbox.