Impact of BMI on Complications, Readmissions, and Perioperative Metrics in a Mature Direct Anterior Approach Total Hip Arthroplasty (THA) Practice

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I commend the authors for the choice of topic and the design of the study.

This is a topic of great clinical relevance, given the increasing prevalence of obesity and the popularity of the Direct Anterior Approach (DAA) in Total Hip Arthroplasty (THA). The central hypothesis of your article is that, even in a mature surgical practice, a high BMI continues to represent a significant risk factor.

I recommend the following suggestions:

• It would be appropriate to specify whether there is a statistically significant difference in comorbidities (such as diabetes, hypertension, rheumatic diseases, etc.) among the different categories of patients.
• it would be useful to report whether greater difficulty was encountered in patient positioning and in the placement of prosthetic components among the different patient categories
• The categories have overlapping ranges (25–30; 30–35; 34–40); it would be preferable to define the exact limits of each group more precisely
• It would be important to clarify whether the procedure required the use of dedicated instrumentation, alternative patient positioning, or the adoption of robotic-assisted techniques

It would also be appropriate to include future perspectives, such as the rigorous implementation of structured preoperative programs that condition surgery on achieving a target BMI or a significant weight loss. Additionally, it would be worth evaluating whether the benefits of the Direct Anterior Approach (e.g., lower risk of early dislocation) translate into improved prosthesis survival in obese patients, who are inherently at higher risk for accelerated wear and long-term aseptic loosening due to increased mechanical load

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This work is devoted to the current medical problem of our time, which consists in improving the quality of total joint replacement and, in particular, hip replacement - THA. Despite the fact that THA is currently considered one of the most high-tech and reliable surgical operations, in some cases postoperative complications occur. The aim of many scientific studies in this area is a comprehensive study of these complications, including the causes of their occurrence, methods and ways to minimize them. Experts note that the main causes of complications arising after THA are mediated by the design of the implant, the quality of the surgical operation and the individual characteristics of the patient. In particular, there is an opinion that a large patient's body weight can increase the risk of postoperative complications. In this regard, THA in patients with a large BMI is planned more carefully and, as a rule, both the operations themselves and postoperative care of patients require more time and financial resources.

In this study, the authors attempted to systematically assess the complications arising after THA, depending on the BMI of patients. Despite the fact that the problem of complications is much more complex, such a formulation of the problem is of certain practical interest. It is necessary to note the well-thought-out methodology of the study by the authors, based on the results of operations performed by one surgeon with extensive experience, which allowed minimizing the variability of indicators, the clarity of the inclusion and exclusion criteria of the studied cases, the division of patients into groups (cohorts) depending on BMI (20-25, 25-30, 30-35, 35-40 kg / m²), as well as the use of correct statistical analysis tests. This allowed the authors to obtain quite plausible results of practical significance for practicing surgeons. It was shown that THA in patients with high BMI is accompanied by large blood loss and requires a longer time, which, in principle, is expected, but postoperative complications and risks of re-prosthetics are close to those observed in patients of the control group, which can be considered an unexpected result.

At the same time, it is necessary to note the limited sample of THA results for the study (only 479 cases, which did not include patients with BMI > 40 kg/m²). That is, the study did not include patients with severe morbid obesity, who may potentially experience serious postoperative complications. In addition, the sample obtained in one clinic based on the THA results performed by one surgeon, along with the minimization of variability of the indicators, contributed to a decrease in the generalization of the conclusions. In addition to BMI, age, % male and three ASA classes were used as demographic indicators, which is clearly insufficient for conducting a comprehensive multivariate analysis of the problem. A significant drawback of the study is that it examined the dependence of complications only on BMI, but ignored other obesity metrics (e.g., fat tissue distribution, visceral obesity), as well as comorbidities. Such important aspects as repeated surgical interventions in the area of ​​planning operations, details of taking hormonal, pain-relieving, anti-inflammatory drugs, compensated chronic diseases, including diabetes mellitus, the presence of varicose veins of the lower extremities, erosions and ulcers of the stomach and intestines, immunodeficiency states, osteoporosis, etc. were not taken into account. In this regard, the results obtained as a result of the study cannot be considered important from a scientific point of view.

At the same time, this work is presented in a sufficiently qualified manner and meets all the requirements of a scientific study, the quality of which can be significantly improved if the above-mentioned comments are eliminated. It is clear that this will be another study, which will analyze a significantly larger sample, segmented not only according to BMI, but also taking into account other patient characteristics.

Taking into account the above, this manuscript can be recommended for publication in the Complications journal, if we consider that it is a prologue to future studies of the problem identified in it.

In particular, it is recommended that a future study:

- increase the number of cohorts by including patients with BMI> 40 kg/m² (morbid obesity and superobesity),

- include cases with different surgical approaches in the samples: anterior, posterior, lateral;

- add an analysis of the resource of implants, quality of life and functional indicators of patients after THA;

- take into account the influence of concomitant factors: diabetes, cardiovascular diseases, levels of physical activity, etc.;

- to assess the impact of increasing the operating time and blood loss on the cost of treatment.

It is also necessary to take into account the fact that the use of data obtained from different clinics and different surgeons in the study will increase its significance and practical value, despite the fact that it will contain some uncertainty due to differences in surgical equipment and surgeons' qualifications.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This single-center, retrospective study (Jan 2021–Jan 2023) examines 479 primary DAA THAs stratified by BMI (20–25, 25–30, 30–35, 35–40 kg/m²). Higher BMI cohorts showed longer operative time and greater estimated blood loss. No deep infections have been observed, and there is an overall complication rate of 3.3%.

The following issues raised my concern and should be addresses:

1. The paper repeatedly reports 479cases (tables and totals), yet the Discussion section it is stated 494 consecutive patients.
2. Specify operational definitions and ascertainment for each endpoint: superficial vs deep infection criteria, diagnostic confirmation for DVT, what qualifies as “PACU dislocation,” and whether assessors were blinded. State how out-of-network events were captured; otherwise acknowledge potential under-ascertainment (particularly readmissions/complications presenting to other facilities). 
3. Excluding BMI >40 kg/m² limits inference to normal-weight, overweight, and class I–II obesity. Reframe conclusions accordingly and discuss generalizability beyond a high-volume, mature DAA practice (single surgeon, single center). 
4. There appears to be a duplicated citation (Horberg et al., Bone Joint J 2021 appears as both #30 and #35). Please de-duplicate and verify all references.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

This is a well-structured and informative study that addresses a relevant clinical topic—evaluating the effect of BMI on outcomes after direct anterior approach total hip arthroplasty (DAA THA). The introduction provides strong context with recent references, and the authors demonstrate awareness of current gaps in the literature. The retrospective design is clearly defined and suitable for the research question.

Strengths of the manuscript include the use of a large consecutive sample from a mature surgical practice, clear stratification of BMI groups, and consistent surgical protocols that minimize confounders. The statistical methods are appropriate, and results are presented clearly in tables that are well-labeled and easy to interpret.

The conclusions are supported by the findings and help clarify that, up to a BMI of 40, complication and readmission rates are not significantly impacted, despite longer operative times and increased blood loss in higher BMI groups.

Suggestions for minor improvement:

• Consider briefly addressing the generalizability of your findings in the abstract, since the study is based on a single-surgeon, single-institution cohort.

• Although the English is clear, a brief editorial review could further tighten some longer sentences for clarity.

Overall, this is a valuable contribution to the literature on DAA THA and obesity-related surgical risks.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors Thank you for the opportunity to review this article. The paper itself is well-structured, the data are clearly presented, and the methods are well-explained. I have no specific questions or comments regarding the paper's structure.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors addressed my question! The review improved the quality of the manuscript. No further questions from my side. 

Reviewer 5 Report

Comments and Suggestions for Authors

I have not major comments