Recognizing the role of preoperative spinopelvic parameter assessment in hip stability

The spinopelvic relationship in total hip arthroplasty

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With the increasing number of patients undergoing total hip arthroplasty (THA) and the significant economic burden associated with revision surgery, improving implant stability has become a major focus in orthopedic surgery. Over the past decade, recognizing the impact of spinopelvic parameters on hip stability has revolutionized our preoperative assessment. As evidenced by recent clinical and biomechanical studies, these strategies can significantly reduce THA dislocation rates.

In Part 2 of our three-part series, Jonathan M Vigdorchik from the Hospital for Special Surgery in New York, United States, guides us through the latest advances in spinopelvic biomechanics. Together, we explore how these findings are reshaping our understanding of hip arthroplasty and why a personalized preoperative strategy is essential to optimize patient outcomes.

Nathanael D Heckmann

Jonathan M Vigdorchik

Hospital for Special Surgery, New York, New York, United States

Beyond the Lewinnek “safe zone”: the importance of spinometric parameters in optimizing THA stability

Total hip arthroplasty (THA) is one of the most successful procedures in orthopedic and trauma surgery [1]. However, despite advances in surgical techniques and implants, postoperative complications remain a challenge for both patients and surgeons. Dislocation is currently the leading cause of revision surgery in the United States, with rates ranging from 0.2% to 10% [2, 3].

Although the incidence of dislocation has decreased, the number of primary THA patients is increasing and may account for an overall increase in postoperative instability. It is estimated that revision THA cases will rise between 78–182% between 2014 and 2030, potentially reaching up to 572,000 cases annually in the United States by 2040 [4]. Acetabular cup orientation is a key factor in THA success, with suboptimal positioning being a major contributor to dislocation. In a review of 380 revision THAs, Novikov et al [5] found that 51% were potentially preventable, with nearly half of these linked to suboptimal acetabular component positioning.

To minimize the risk of dislocation after primary THA, Lewinnek et al [6] proposed a “safe zone” for acetabular cup orientation of 40° ± 10° inclination and 15° ± 10° anteversion. These guidelines became widely adopted; however, numerous authors have challenged the validity of the Lewinnek safe zone as a universal standard for component orientation. Studies have shown that up to 60% of dislocations occur despite cup orientations falling within the radiographic inclination/anteversion boundaries described by Lewinnek [7–9]. So why do acetabular cups that appear to be within the safe zone still dislocate? Clearly, additional factors are at play.

Hip arthroplasty surgeons are increasingly recognizing the dynamic interplay between the hip, spine, and pelvis and its impact on prosthesis stability, wear, and overall function. It is now well established that these structures move in coordination, with the orientation of the acetabulum shifting between positions such as standing and sitting. Patients with concomitant hip and spinopelvic pathology experience higher rates of postoperative complications [10–12]. For instance, DelSole et al [13], in a study evaluating 139 THAs in 107 patients with spinal deformity, found that this cohort had a dislocation rate of 8%, compared to just 1.5% in the control group.

Vigdorchik notes, “recognizing the interplay between the hip and spine is essential for improving clinical assessment, surgical planning, and postoperative outcomes. The current body of work addresses this oversight by highlighting the influence of spinopelvic alignment on hip stability and the need for a more personalized preoperative approach. We now understand that certain patients are at higher risk of complications, but by adjusting the surgical plan, we can reduce that risk; therefore, we need to identify those at-risk patients and tailor the surgical approach to decrease that risk”.

 

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  • Preoperative spinopelvic assessment matters
  • Beyond Lewinnek’s “safe zone”
  • Spinopelvic parameter standardization
  • Hip-Spine Classification
  • Preoperative functional imaging
  • Confirming clinical outcomes
  • Conclusion
The spinopelvic relationship in total hip arthroplasty
Part 1 | Mechanics and dislocation risk
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The spinopelvic relationship in total hip arthroplasty
Part 3 | Modifiable intraoperative factors
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Contributing experts

This series of articles was created with the support of the following specialists (in alphabetical order):
George Grammatopoulos

George Grammatopoulos

The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada

Nathanael D Heckmann

Nathanael D Heckmann

Keck Medical Centre, University of Southern California, Los Angeles, California, United States

Jonathan M Vigdorchik

Jonathan M Vigdorchik 

Hospital for Special Surgery, New York, New York, United States

This article was written by Chiara Cianciolo, AO Innovation Translation Center, Clinical Evidence, Switzerland.

References

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