Surgical Approach Tied to Risk in Hip Replacement

Laird Harrison

March 23, 2020

The anterior approach to hip arthroplasty is slightly riskier than the posterior or lateral approaches, researchers say.

"The small but statistically significant increased risk of major surgical complications associated with the anterior approach may help inform decisions for total hip arthroplasty," write Daniel Pincus, MD, PhD, of the Sunnybrook Health Sciences Center in Toronto, Canada, and colleagues.

Three primary approaches are available for surgeons performing hip arthroplasty. Lateral and posterior approaches both offer good visualization and are easily extensible if necessary. However, the lateral approach may lead to limping, owing to splitting of the abductor muscles, and the posterior approach is associated with a higher risk for dislocation. The anterior approach reduces these risks by utilizing the natural plane between muscles. But with this approach, there is an increased risk for nerve injuries, fractures, and infections.

To find out which approach carried the greatest overall risk for complications, Pincus and his colleagues conducted a population-based retrospective cohort study of all adults in Ontario, Canada, who had undergone total hip arthroplasty (THA) for osteoarthritis between April 1, 2015, and March 31, 2018. Their findings were published online March 17 in JAMA.

The researchers analyzed the data by matching patients who had undergone an anterior THA with patients who had undergone a lateral or posterior approach. Patients were matched in a 1-to-1 ratio.

Patients were assigned scores that were calculated on the basis of the following potentially confounding variables: patient health status, physician and hospital characteristics (annual surgeon and hospital volume), and sociodemographics (age, sex, rural residence, income quintile, year of surgery). The patients were matched to patients with similar scores who had undergone a different treatment approach.

The researchers were able to match 2993 patients who had undergone an anterior THA with 2993 patients who had undergone either a lateral or a posterior THA.

The researchers calculated percent absolute risk differences in the cumulative incidence of major surgical complications.

They determined that patients who had undergone an anterior THA had a 2% chance of experiencing surgical complications within 1 year of their procedure and that patients who had undergone a lateral or anterior operation had a 1% chance of experiencing complications (P < .001). The absolute risk difference was 1.07% (95% confidence interval, 0.46% – 1.69%).

Rates of complications were similar for posterior and lateral approaches.

The study has several limitations, including a lack of data on postoperative protocols, pain scores, or short-term functional outcomes. In general, the anterior-approach group was somewhat younger and healthier and spent less time on average in the hospital (interquartile range, 1 – 3 days with the anterior approach vs 2 – 3 days with the posterior or lateral approaches).

Brian Hallstrom, MD, and Richard Hughes, PhD, both of the University of Michigan in Ann Arbor, note in an accompanying editorial that anterior arthroplasty is a relatively new procedure in Ontario and entails a significant learning curve, which may have influenced the observed rate of surgical complications.

"Despite these limitations, this study provides orthopedic surgeons and primary care physicians with important information that may be helpful when having an informed discussion with patients about the risks and benefits of their potential hip surgery," Hallstrom and Hughes write.

They add that the research by Pincus and colleagues provides useful data for clinicians, especially when combined with another new study published in the same issue of JAMA.

The second study, by Kanu Okike, MD, and colleagues of the Moanalua Medical Center in Honolulu, Hawaii, is a retrospective cohort study of 12,491 elderly Kaiser Permanente hemiarthroplasty patients. The data show a 3.0% risk for aseptic revision at 1 year after operation with uncemented fixation, vs a 1.3% risk with cemented fixation. The difference was statistically significant (P < .001).

These findings are important, Hallstrom and Hughes say, because fewer than half of femoral stems were cemented in 2018, despite the American Academy of Orthopaedic Surgeons' guidelines that recommend cementing femoral stems.

Hallstrom and Hughes say that more research is needed, although randomized controlled trials may not be feasible in addressing the questions in these studies. The editorialists call for surgeons to carefully review the outcomes analyses of procedures such as these as recorded in surgical registries.

The study by Pincus and colleagues was supported by the Marvin Tile Chair in Orthopaedic Surgery at Sunnybrook Health Sciences Center, Toronto, and by the Ontario Ministry of Health and Long-Term Care. No funding was reported for the study by Okike and colleagues. One coauthor of the Pincus study has received personal fees from DePuy Synthes and works at an institution that receives support from Zimmer Biomet and Smith+Nephew for research and fellowships. Hallstrom and Hughes have received partial salary from Blue Cross Blue Shield of Michigan. The other authors have disclosed no relevant financial relationships.

JAMA. Published online March 17, 2020. Pincus et al, Full text; Okike et al, Abstract; Editorial

Dashiell Harrison contributed to this article.

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