SuperPATH—Current Status of Evidence and Further Investigations: A Scoping Review and Quality Assessment

Background: SuperPATH is a novel minimally invasive technique for hip replacement that is gaining increasing attention. The aim of this review was to determine the nature, extent, and quality of current research evidence on SuperPATH and to identify areas for further investigations. Methods: A bibliometric search was conducted in PubMed up to 1 August 2023 using the search term “SuperPATH”. Data extraction and quality assessment were performed for relevant articles. Results: The bibliometric search yielded 51 articles on SuperPATH, 9 of which were meta-analyses, 11 were randomized controlled trials (RCTs), 4 were prospective non-RCTs, 12 were retrospective comparative studies, 11 were case series, and 4 were other article types. Most articles were published between 2015 and 2023, with a steady increase in publications per year. The articles originated from 13 countries, of which China was the most productive (35%). The quality assessment of the meta-analyses showed that 22.2% were of moderate quality, 66.7% were of low quality, and 11.1% were of critically low quality. The quality assessment of the RCTs showed that 36.4% had a low risk of bias (RoB), 27.2% revealed some concerns, and 36.4% had a high RoB. All studies were evaluated for content and taken into account in the formulation of recommendations and conclusions. Conclusions: The SuperPATH evidence varies from low to high quality. There is a steady increase in SuperPATH publications in the English-language literature and an uneven distribution of the article origins, with most articles coming from China. Consistent terminology should be used in the future, referring to the surgical approach as the direct superior approach (DSA) and to the surgical technique as SuperPATH. This review provides further concrete suggestions for future investigations and recommendations to improve study quality.


Introduction
Total hip arthroplasty (THA) is one of the most successful surgical procedures of the 20th century [1].It allows patients with various hip disorders to restore their joint function and improve their quality of life.In addition, THA or hemiarthroplasty (HA) is a surgical solution for the treatment of femoral neck fractures (FNFs) [2].In an effort to improve the short-term outcomes after THA, several minimally invasive (MI) approaches have been invented and established in practice.In general, MI approaches are modifications of conventional approaches (CAs) that use smaller incisions and cause less soft tissue and muscle damage.Therefore, it is widely agreed that a hip approach can be considered MI if it meets two conditions: a skin incision length of <10 cm and, more importantly, no dissection of tendons and muscles.Three approaches fulfill these requirements: the direct anterior approach (DAA) using the anterior minimally invasive surgery (AMIS) surgical technique [3], the anterolateral approach (ALA) using the anterolateral minimally invasive (ALMI) surgical technique [4], and the direct superior approach (DSA), using the supercapsular percutaneously assisted total hip (SuperPATH) surgical technique [5]. Figure 1 provides a topographical overview of the skin incision of the different hip approaches.
geons who have experienced its benefits in practice.However, it is striking that despite the promising results of SuperPATH, there are relatively few studies in the English language literature.
The aim of this study was to conduct a scoping review of the literature on SuperPATH to determine the nature, extent, and quality of current research evidence and to identify areas for further investigations.direct anterior approach (DAA); orange line: anterolateral approach (ALA); yellow line: lateral approach (LA); red lines: direct superior approach (DSA) with additional stab incision; blue line: posterior/posterolateral approach (PA/PLA).

Scoping Review
According to Grant and Booth [8], a scoping review is a "preliminary assessment of potential size and scope of the available research literature" that "aims to identify nature and extent of research evidence" [8].According to Munn et al. [9], a scoping review answers broader questions than the widely known systematic review "beyond those related to the effectiveness of treatments or interventions" [9].direct anterior approach (DAA); orange line: anterolateral approach (ALA); yellow line: lateral approach (LA); red lines: direct superior approach (DSA) with additional stab incision; blue line: posterior/posterolateral approach (PA/PLA).
SuperPATH was introduced in 2011 by James Chow [5], combining the advantages of two microposterior approaches-the supercapsular approach (SuperCap), developed by Stephen Murphy in 2004 [6], and the percutaneously assisted total hip approach (PATH), developed by Brad Penenberg in 2008 [7].SuperCap allows access to the superior capsule using a DSA without causing relevant soft tissue and muscle damage [6].PATH is a portalassisted approach that provides the ability to achieve consistent and accurate acetabular cup positioning without causing relevant soft tissue and muscle damage [7].Since its inception, SuperPATH has gained increasing support among orthopedic surgeons who have experienced its benefits in practice.However, it is striking that despite the promising results of SuperPATH, there are relatively few studies in the English language literature.
The aim of this study was to conduct a scoping review of the literature on SuperPATH to determine the nature, extent, and quality of current research evidence and to identify areas for further investigations.

Scoping Review
According to Grant and Booth [8], a scoping review is a "preliminary assessment of potential size and scope of the available research literature" that "aims to identify nature and extent of research evidence" [8].According to Munn et al. [9], a scoping review answers broader questions than the widely known systematic review "beyond those related to the effectiveness of treatments or interventions" [9].

Search Strategy
A bibliometric search was performed in PubMed up to 1 August 2023 without language or year of publication restrictions.The exact search string used was "SuperPATH" with no filters applied.As the PubMed bibliometric search was intended to identify all published articles on SuperPATH, the selection criteria for article inclusion were as follows: any type of record in PubMed dealing with the topic of "SuperPATH".Records were only excluded from the scoping review if they were not related to SuperPATH.This scoping review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines [10].The PRISMA-ScR checklist [10] is available in the Supplementary Materials.The study protocol has been registered in the Open Science Framework, available online at: https://osf.io/nd2s5/accessed on 25 June 2023.

Data Extraction and Quality Assessment
The following data were extracted from relevant articles: author's name, year of publication, origin, and language of the article, article methods, main findings, and relevant additional information.In addition, the quality of relevant articles was assessed using the revised Measurement Tool to Assess Systematic Reviews (AMSTAR 2) [11] for metaanalyses, the revised Cochrane Risk of bias tool (RoB 2) [12] for randomized controlled trials (RCTs) and the Risk of bias in non-randomized studies of interventions (ROBINS-I) tool [13] for non-RCTs.The bibliometric search, data extraction, and quality assessment were conducted by two reviewers (NR, PMK).The inter-reviewer agreement was measured with the Cohen's Kappa coefficient (κ).In the case of disagreement, consensus was reached after scientific discussion.
. Meta-analyses quality assessment, using AMSTAR 2 (A MeaSurement Tool to Assess Systematic Reviews 2).Possible assessment results: "Critically low", "Low", "Moderate", "High".Note that the labels refer to quality and not RoB, e.g., "low" is bad, and "high" is good.The meaning of "low" and "high" is reversed in the RoB 2 tool compared to AMSTAR 2. RoB: risk of bias.
clarify whether the additional stab incision was omitted in SuperPATH HA.No matter how small this additional stab incision may be, its omission still suggests, to some extent, less soft tissue and muscle damage.Another important piece of information that was rarely reported is the blinding process in RCTs.This shortcoming consequently leads to a lower level of quality in the RoB assessment [27][28][29][30][31]35,36].
The next interesting point raised by 4 articles of this scoping review [39,42,47,55] is the learning curve of the SuperPATH technique.In an analysis of 50 consecutive SuperPATH operations performed by a non-developing surgeon, the learning curve was assessed using the operation time as a surrogate [42].Rasuli and Gofton found that the mean operation time of SuperPATH was 101.7 ± 18.3 min, with a further decrease after case 50 [42].In their analysis of 78 consecutive SuperPATH operations (80 hips) performed by the same surgeon, the authors Lei et al. came to similar findings [47].In addition, they concluded that surgeons who are familiar with the conventional PLA may achieve greater comfort with SuperPATH after 40 cases of surgery [47].In a prospective study, Más Martínez et al. compared 30 cases of SuperPATH THA with 60 cases of conventional PA THA [39].The learning curve of SuperPATH provided similar outcomes to the conventional PA within the first year after surgery [39].A case series of 100 consecutive patients by Della Torre et al. [55] analyzed the SuperPATH THA component position and seating, femoral offset, and leg length.The authors concluded that the implant position was optimal within the learning curve for the described THA safe zones [55].The learning curve described in SuperPATH can certainly be explained by the fact that SuperPATH is a novel technique that requires special instruments and surgical skills.The interesting question here is how the cost of THAs compares.Obviously, there is a cost associated with the purchase of the specialized SuperPATH instruments.Whether these costs can be offset by the better short-term outcome of SuperPATH [18][19][20][21][22][23][24][25] and the associated shorter hospital stay [25] remains to be scientifically investigated.
Based on the review of the articles, the following suggestions for future research emerge: (1) There are only two meta-analyses comparing the individual CA separately with SuperPATH [25,26].Most meta-analyses grouped the CAs together [18,[20][21][22][23][24], which is a serious limitation.Further publications are needed to overcome this limitation.(2) SuperPATH has already been compared with DAA in meta-analyses [19,21,25,26].However, this could only be performed via an indirect comparison using a network meta-analysis, as there are still no published RCTs directly comparing SuperPATH with DAA.These preliminary indirect comparisons showed overall better results for SuperPATH.The validity of these preliminary results urgently needs to be confirmed by direct comparisons in RCTs and meta-analyses.(3) There are no meta-analyses comparing SuperPATH with other MI techniques (other than DAA) or to robotic-assisted THA techniques.(4) Although there are some RCTs [30,[32][33][34][35][36][37] that have evaluated the laboratory parameters after SuperPATH hip replacement, these data have not yet been pooled in a meta-analysis.A meta-analysis of laboratory parameters would provide a reliable picture of the extent of tissue damage and blood loss.(5) Furthermore, there is no meta-analysis examining the outcome of SuperPATH HA.Research on this topic is important because, as mentioned above, there are key differences in surgical approach and technique between SuperPATH THA and SuperPATH HA.The impact of omitting the additional stab incision in HA needs to be investigated.( 6) While many meta-analyses [18][19][20][21][23][24][25][26] and RCTs [27,28,30,[32][33][34][35][36][37] have investigated the acetabular cup positioning of SuperPATH, there is no radiographic analysis of the stem positioning in the literature.Filling this scientific gap is important because the SuperPATH technique involves implanting the femoral stem in situ prior to femoral neck resection.This is a completely new procedure in arthroplasty, the results of which need to be studied.(7) There is also a lack of studies in the literature on revision THA through SuperPATH and on mid-and long-term outcomes of SuperPATH.
To be further investigated: -RCTs and meta-analyses of SuperPATH vs. each CA separately (ALA, LA, PA, PLA); -RCTs and meta-analyses of SuperPATH vs. DAA in direct comparison; -RCTs and meta-analyses of SuperPATH vs. other MI techniques (except of DAA) or vs. robotic-assisted techniques; -Meta-analyses of the laboratory parameters of SuperPATH vs. other techniques; -RCTs and meta-analyses of SuperPATH HA; -RCTs and meta-analyses of the stem positioning through SuperPATH; -RCT and meta-analyses of revision THA through SuperPATH; -RCTs and meta-analyses of mid-and long-term outcomes of SuperPATH.
Recommendation for future studies: -Standardization of terminology: SuperPATH is the designation of a hip replacement technique that uses a direct superior approach (DSA); -Report the use of bone cement; -Report information on the additional stab incision: -Do you report an added incision length of both incisions (additional stab incision + main incision) in SuperPATH THA or just the main incision?-Did you omit the additional stab incision in SuperPATH HA?
The following limitations of this scoping review should be noted: (1) The bibliometric search was limited to only one database (PubMed).( 2) The meta-analyses and RCTs on SuperPATH were given more attention in this scoping review because they are at the forefront of evidence-based medicine.However, there may be relevant findings in the other studies.(3) The recommendations and conclusions of this scoping review are based on a scientific interpretation of the primary studies, but there may still be some degree of subjectivity based on the author's expert opinion.

Conclusions
The research evidence on SuperPATH varies from low to high quality.There is a steady increase in publications on SuperPATH in the English language literature and an uneven distribution of article origins, with most articles coming from China.The current state of the literature suggests that SuperPATH THA has a better short-term outcome than CA THA.Consistent terminology should be used in the future, referring to the surgical approach as DSA and to the surgical technique as SuperPATH.Numerous other gaps in the specialist literature were identified.This review provides concrete suggestions for future investigations and recommendations to improve study quality.

Figure 1 .
Figure 1.Topographical overview of the skin incision of the different hip approaches.Green line:direct anterior approach (DAA); orange line: anterolateral approach (ALA); yellow line: lateral approach (LA); red lines: direct superior approach (DSA) with additional stab incision; blue line: posterior/posterolateral approach (PA/PLA).

Figure 1 .
Figure 1.Topographical overview of the skin incision of the different hip approaches.Green line: direct anterior approach (DAA); orange line: anterolateral approach (ALA); yellow line: lateral approach (LA); red lines: direct superior approach (DSA) with additional stab incision; blue line: posterior/posterolateral approach (PA/PLA).

J 19 Figure 2 .
Figure 2. Temporal analysis of publication output.

Figure 3 .
Figure 3. Publication output per country.Note that some studies originate from two countries, which is why the total number of studies is 63.USA: United States of America; UK: United Kingdom.

Figure 3 .
Figure 3. Publication output per country.Note that some studies originate from two countries, which is why the total number of studies is 63.USA: United States of America; UK: United Kingdom.

Figure 3 .
Figure 3. Publication output per country.Note that some studies originate from two countries, which is why the total number of studies is 63.USA: United States of America; UK: United Kingdom.