Commentary & Perspective

Commentary & Perspective on
"Internal Fixation Compared with Arthroplasty for Displaced Fractures of the Femoral Neck. A Meta-Analysis"
by Mohit Bhandari, MD, MSc, et al.

Commentary & Perspective by
Daniel J. Berry, MD*,
Mayo Clinic, Rochester, Minnesota

The paper entitled "Internal Fixation Compared with Arthroplasty for Displaced Fractures of the Femoral Neck. A Meta-Analysis," which was published in the September 2003 issue of The Journal, provides the best and most scientifically valid analysis of the relative merits and demerits of these two treatment modalities ever published. The authors conclude that for patients older than sixty-five years of age, "…in comparison with internal fixation, arthroplasty for the treatment of displaced femoral neck fractures significantly reduces the risk of revision surgery at the cost of greater infection rates, blood loss, and operative time and possibly an increase in early mortality." Most orthopedic surgeons who treat patients with hip fractures will believe the correctness of this conclusion both intuitively and based on experience.

The results and conclusions of the paper are based on meta-analysis methodology, which involves a thorough literature search and grading of the quality of papers on the subject. Only papers with high-quality evidence are included in the study. The data from the eligible studies then are pooled and analyzed, thereby gaining the benefits of greater statistical power provided by a large number of patients. The authors' methodology for conducting the meta-analysis is well documented in the paper, is exhaustive, and is of the highest scientific quality. Importantly, the authors chose to review only papers published in English, which they recognize as a possible but unlikely source of bias in their study. Remarkably, despite the millions of patients treated for this diagnosis over the last three decades, the authors found only fourteen studies, comprising a total of 1933 patients, with a sufficient level of evidence to be eligible for their study. While the number of patients analyzed limited the authors' ability to draw firm conclusions about the comparative risk of mortality between the two treatment regimens, the population was sufficiently large to draw firm, statistically valid conclusions for many other parameters.

The most important finding of the study, and the finding with the strongest statistical backing, is that arthroplasty reduces the rate of early reoperation for this diagnosis in older patients compared with the rate associated with internal fixation. Notably, the highest-quality studies showed the strongest benefit of arthroplasty, which further buttresses the validity of the finding that arthroplasty reduces the rate of early reoperation. The relative risk of reoperation following arthroplasty was 0.23 (95% confidence interval: 0.13 to 0.42, p = 0.0003) compared with internal fixation. This means arthroplasty reduced the risk of early reoperation by 77% compared with internal fixation. Looking at the same data differently, the authors state "…for every 100 average patients treated with arthroplasty instead of internal fixation, seventeen revision surgeries can be avoided…." Arthroplasty had an even more powerful effect in reducing reoperation in patients with cognitive impairment. Recognizing that arthroplasty nullifies the chances of fracture nonunion and femoral head osteonecrosis (complications reported in the meta-analysis to occur in a mean of 18.5% and 9.7% of patients, respectively, treated with internal fixation), the lower rate of reoperation in patients treated with arthroplasty is believable.

Not surprisingly, arthroplasty was found to increase blood loss (by a mean of 176 mL), surgical time (by a mean of 29 minutes), dislocation, and infection. For 100 average hypothetical patients, the authors found the benefits of arthroplasty came "…at the expense of one hip dislocation and four more wound infections." These findings are consistent with the understanding by most orthopedic surgeons that arthroplasty imparts a slightly larger initial physiologic insult compared with most internal fixation procedures, and that it carries higher risks of infection and dislocation than internal fixation does.

Pain relief and function were similar in patients treated with arthroplasty and patients treated with internal fixation. Importantly, however, the authors found that only six of the fourteen studies in their meta-analysis reported on pain relief and only twelve reported on function. More detailed comparative information on these parameters will be needed from studies that are specifically designed for the evaluation of pain and function after these operations.

The most important question this paper leaves unanswered is the effect of treatment on mortality following this injury, because the study is "underpowered," i.e., it contains too few patients for it to be used as a reliable assessment of the differences between the groups for this variable. The authors found a slight trend toward increased mortality in patients treated with arthroplasty compared with internal fixation at four months (relative risk: 1.27 [95% confidence interval: 0.84 to 1.92], p = 0.25) and at one year (relative risk: 1.04 [95% confidence interval: 0.84 to 1.29], p = 0.68). However, for patients with cognitive impairment, arthroplasty appeared to reduce the risk of mortality compared with internal fixation (relative risk: 0.75). The reader may conclude that if arthroplasty does increase the risk of death, the increased risk probably is quite small. Nevertheless, the importance of a difference in the rate of this most serious complication, even if small, cannot be overlooked. The authors conclude by making the case for a large prospective randomized trial to answer this question definitively. Unfortunately, the large number of patients required (up to 26,641 by one of their estimates) may prove to be an impediment. To provide the most useful information, future studies will need to account not only for mortality related to the first operation after fracture but also for mortality related to subsequent early reoperations related to initial treatment failures, which are more common in patients treated with internal fixation.

As with all good papers, this study raises a number of important questions for future study. The meta-analysis could not provide definitive information on the risks compared with the benefits of certain technical features of each treatment. For example, for internal fixation, the risks and benefits of a sliding hip screw compared with multiple screws remain uncertain, and for arthroplasty, the merits of monopolar hemiarthroplasty, bipolar hemiarthroplasty, total hip arthroplasty, and different operative approaches all remain undefined.

The best treatment for displaced femoral neck fractures in older patients has long been debated, and this meta-analysis will not put an end to the controversy. Recent data from a detailed survey in California suggest that in the United States, most displaced femoral neck fractures in older patients are treated with arthroplasty.¹ The data presented in the paper provide orthopaedists with valuable, and previously unavailable, information on the relative risks of reoperation, complications, and mortality following arthroplasty and internal fixation; this information will provide practical decision-making benefits in day-to-day practice.

*In support of their research or preparation of this manuscript, one or more of the authors received grants or outside funding from DePuy. In addition, one or more of the authors received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity (DePuy). Also, a commercial entity (DePuy) paid or directed, or agreed to pay or direct, benefits to a research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

References

1. Lieberman JR, Moehring HD, PS, Cholcott-Lockwood M, Schembri M, Romano PS: How are hip fractures really treated by the orthopaedic community? Read at the Annual Meeting of the American Academy of Orthopaedic Surgeons; 2002 Feb 13-17; Dallas, TX.