A systematic review and meta-analysis of SuperPATH approach in hip arthroplasty

Background: To compare the clinical and radiographic results of supercapsular percutaneously assisted total hip (SuperPATH) approach and conventional approach by systematic review and meta-analysis. Methods: Based on a pre-published protocol (PROSPERO CRD42020177717), we systematically retrieved databases from Pubmed, Embase, Cochrane and Web of Knowledge for relevant literatures from the earliest available date to May 30, 2020. No language restriction was applied. RevMan 5.3 software was used to perform the meta-analysis. The methodological qualities were assessed using the guidelines provided by the Cochrane Collaboration for Systematic Reviews. Two reviewers were independently extracted data from all eligible studies, including types of studies, participants, interventions, and outcomes. Randomized or xed-effect models were used to calculate the weighted mean difference (WMD), odds ratio (OR) for continuous and dichotomous variables, respectively. Results: 6 articles were included in the study and 526 patients were selected, which was including 233 cases in the SuperPATH groups, 279 cases in the conventional groups and 4 cases performed two surgeries in succession. The SuperPATH group demonstrated shorter incision length (WMD = - 7.87, 95 % CI -10.05 to - 5.69, P < 0.00001), decreased blood transfusion rate (OR = 0.48, 95 % CI 0.25 to 0.89, P = 0.02), decreased visual analogue scale (VAS) (WMD = -0.40, 95 % CI - 0.72 to - 0.08, P = 0.03) and higher Harris hip score (HHS) (WMD = 1.98, 95 % CI 0.18 to 3.77, P = 0.0002) than those in the conventional group. However, there was no difference in VAS and HHS between the two groups half a year later. There was no signicant difference in the acetabular abduction angle (WMD = - 1.32, P = 0.32) in either group. Conclusions: SuperPATH minimally invasive approach with its reduced tissue damage, quick postoperative recovery and early rehabilitation demonstrates the short-term advantages of hip arthroplasty. However, the evidence for SuperPATH technique was limited in the number of studies and from the of the of case characteristics, Outcome skin-to-skin operation of transfusion hospitalization anteversion angle and acetabular abduction angle), postoperative VAS and HHS at 1 week, 1 3 6 after


Literatures search strategies
A computerized retrieval of relevant literatures from Pubmed, Embase and Cochrane library were performed from their inception to May 30, 2020.All aspects of the international systematic review were followed using the Cochrane handbook and the study was written according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement [7].Using the keywords and MeSH search strategy, the Pubmed search method was shown in Fig. 1.

Inclusion criteria
(1) Population: Degenerative hip arthritis, avascular necrosis of the femoral head or fresh femoral neck fractures.
(4) Types of outcomes: skin-to-skin operation time, length of incision, blood loss, blood transfusion rate, hospitalization time, visual analogue score (VAS), Harris hip score (HHS) and imaging measurements (acetabular anteversion angle and acetabular abduction angle).At least one of these items was reported.

Literature search results
A total of 392 articles were initially found and 127 articles were excluded for repeated publishing.By reading titles and abstracts, 239 pieces of literature were excluded from reviews, case reports and irrelevant studies.For no comparison of two approaches and literature that was not related to the purpose of the study, 8 documents were screened out.To further read the full text, we found a lack of required data in 9 pieces of literature and 3 pieces of literature included other irrelevant interventions.Finally, 6 articles [10][11][12][13][14][15]were selected.The PRISMA literature inclusion and exclusion process were shown in Fig. 2.

The basic characteristics and quality evaluation of included studies
The basic characteristics of the 526 patients were shown in Table 1.Concerning the body mass index, one of the study [15] was not mentioned.Regarding RCTs, there were a total of 3 studies [10,11,15] that were enrolled in this article.Due to the particularity of surgery, all of these three studies did not report the methods of binding to participants and/or operators.Besides, one paper [10] explained the randomization but no randomized paired design was mentioned.
None of the 3 RCTs had a de ciency of being incomplete outcome or existing detection bias.The risk of bias graph and summary for these 3 studies were all shown in Figs. 3 and 4. As shown in Table 2, the NOS scores of these three cohort studies [12][13][14] were 8, 8 and 8, respectively.In general, all of the 6 articles included in this study were of good quality, with standardized research design and good research value.The number of studies enrolled was less than 10 and therefore no publication bias was conducted.

Data extraction and quality assessment
Two reviewers were independently in accordance with the inclusion criteria for the quality of the literature evaluation and data extraction and then crosschecked.If there were any disagreements between them, a senior (Peijian Tong) would make a decision.The randomized controlled trials (RCTs) were evaluated for quality using the Cochrane risk assessment tool [8].The Newcastle-Ottawa Scale (NOS) [9] was used for the quality assessment of cohort studies.This scale includes three major parts, such as the selection of study groups, ascertainment of exposure and outcome as well as group comparability.
The general scores greater than or equal to 7 were considered low risk of bias.
The following information was extracted from the study: (1) Characteristics of the studies (author, published time, disease, surgery, type of study, case characteristics, etc. ).( 2) Outcome indicators: skin-to-skin operation time, length of incision, blood loss, blood transfusion rate, hospitalization time, imaging measurements (acetabular anteversion angle and acetabular abduction angle), postoperative VAS and HHS at 1 week, 1 month, 3 months and 6 months and 1 year after surgery.

Statistical methods
Meta-analysis was performed using the Revman5.3 (Cochrane Collaboration, Copenhagen, Denmark) software for the available indicators.For the dichotomous variable, the ORs (odds ratios) and 95% CI (con dence interval) were used as the effect indicators.For the continuous variables, the WMD (weighted mean difference) and 95%CI were used as the effect indicator.When statistical heterogeneity of study did not exist (P ≥ 0.1 or I² 50%), the xedeffects model was used.When statistical heterogeneity existed (P 0.1 or I² 50%), the random-effects model was used for data synthesis.The results of this meta-analysis were shown in the forest-pot, and P < 0.05 was considered as statistically signi cant.

Discussion
Early surgical intervention was often considered as the preferred choice for the treatment of a variety of hip diseases.Not only for rehabilitating earlier, but also for reducing the risk of various serious complications of being prolonged bed rest [16,17].With the continuous development of minimally invasive techniques, the patients' needs for rapid rehabilitation put considerable pressure on surgeons and other health care professionals.Consequently, we achieved excellent results in early functional recovery and short hospital stays [18].Based on the evidence, Ibrahim MS et al [19] pointed out that minimally invasive surgery and fast-track arthroplasty units can be used to achieve rapid recovery, reduce hospital stays and improve functional outcomes after total hip arthroplasty (THA).THA raised the possibility of improving the clinical outcome and reducing surgical injury [20][21][22].Patients were also more inclined to accept minimally invasive surgery.
SuperPATH technology was pioneered by Dr. James Chow of St. Luke's Medical Center in Phoenix, USA [2].This technique combined Dr. Stephen Murphy's Supercap (MicroPort Orthopedics Inc., Arlington, TN, USA) technique [4] with Dr. Brad Penenberg's PATH (MicroPort Orthopedics Inc., Arlington, TN, USA) technique [23], which was a revolutionary technology to achieve a real minimally invasive.This approach was consistent with the anatomical landmarks of the conventional posterolateral approach, preserving all the advantages of the standard posterolateral approach, and special operative tables were no longer required.What's more, it can be easily converted to a standard posterior approach.In the process of soft tissue separation, SuperPATH technology did not transversely cut off muscles and tendons, preserving the integrity of the external rotators around the joint capsule.Furthermore, acetabular preparation can be easily done with the aid of the other percutaneous incision, thus providing rapid postoperative recovery with its intact muscles.Consequently, patients who underwent SuperPATH acquired faster recovery of postoperative activities.
This was the rst systematic review and meta-analysis that comparing SuperPATH approach and conventional approach in hip arthroplasty.The result showed that 6 studies (two RCTs and 4 CCTs) met inclusion criteria for this systematic review and meta-analysis.In terms of incision length, all 4 studies showed that the average length of the surgical incision in the SuperPATH group was shorter than that in the conventional group.Also, compared with the greater trauma of the conventional approach, minimally invasive surgery cannot be de ned by short incision solely.For instance, direct anterior access may injury the lateral femoral cutaneous nerve [24]; lateral approach may injure the superior gluteal nerve and cut off the insertion of gluteus minimus [25]; the posterior lateral approach needed to cut the piriformis muscle and then expose joint capsule [26].In terms of minimally invasive surgery, the SuperPATH technology was a true minimally invasive technique.Not only for its minimal incision but also for protecting the external muscles and ligaments by means of not cutting them off.As we violently pull distal or proximal soft tissue during the process of surgery, there was a possibility of reducing postoperative incision necrosis, subcutaneous fat liquefaction and other complications for the other minimally invasive THA.Thus, the obese and stiffness of muscles were relatively contraindications for other surgical options.In the meantime, on account of a short incision, lacking eld of vision and unclear anatomical landmarks, mini-invasive surgery may result in the inaccuracy of prosthesis placement.However, the SuperPATH technique was not a contraindication to obesity and muscularity, which further broadens the indications for resolution of intraoperative joint capsule exposures and anatomic landmarks [2].Eskelinen A [27] suggested that we should pay more attention to the protection of tissue and placement of the prosthesis, but put the short incision (≤ 10 cm) into the secondary site simultaneously.Han SK et al [28] found that intraoperative protection of the external rotation muscles can reduce the postoperative dislocation rate from 1.8-6.2%.
In this study, 6 papers documented operation time.The results of this issue showed that there was no difference in operating time between the two groups, which may be closely related to the learning curve of the new SuperPATH technology.Rasuli KJ et al [6] reported 50 cases and 49 cases of SuperPATH and PATH minimally invasive approach for total hip arthroplasty respectively.They found that the operation time of the 50th case in the SuperPATH group was still in the process of decreasing, indicating that the learning curve can certainly prolong the operation time.Besides, the step of suturing the incision was often performed by junior physicians at the end of the surgical, and may to some extent affected the overall operation time.
Blood loss and transfusion rates in prosthetic hip operation were closely associated with the bleeding in the process of the osteotomy, intramedullary reaming of medullary cavity and cutting muscles.For the SuperPATH approach, smaller soft tissue dissection should be related to less bleeding as well as fewer transfusions rates.In this research, 6 studies mentioned intraoperative blood loss and blood transfusion rates were mentioned in 4 studies.There was no signi cant difference in intraoperative blood loss, but blood transfusion rates were signi cantly lower in the SuperPATH technique.The author believed that SuperPATH technology protects the joint capsule and external rotation muscles, which led to the possibility of less trauma, so the overall transfusion rate was less than the conventional group.As a new technique, surgeons may prolong operation time and increase blood loss for unskilled operation.Gofton W et al [5] and Rasuli et al [6] who performed this surgery, found the transfusion rates of SuperPATH minimally invasive surgery were 3.3% and 4.0% respectively, which were lower than those in the conventional approaches.
3 studies related to hospitalization time.The results showed that there was no signi cant difference between both.Cardenas-Nylander C et al [29] showed that the average length of stay undergoing SuperPATH technology was 1.4 days, less than that of the conventional THA.Gofton W et al [30] conducted a study of 30-day readmission rates for 479 patients who performed THA.The results showed that the 30-day readmission rate for the SuperPATH minimally invasive total hip arthroplasty fell from 4.3-2.3%compared with conventional procedures.Gofton W et al [5] analyzed 99 patients from April 2013 to January 2014.They found that even if the surgeons came into contact with SuperPATH, the overall costs of hospitalization were 28.4% lower than that of the conventional lateral approach.Thus, it signi cantly reduced postoperative costs.In this study, Meng et al [14] performed bilateral hip arthroplasty in succession and may reduce the whole length of stay to enhance recovery after surgery.
4 studies mentioned VAS and the subgroup analysis found that 1 week, 1 and 3 months after surgery in SuperPATH technology was signi cantly lower than in conventional surgery.However, results showed that during the 6 to 12 months follow-up of two groups, there had no difference in two groups.Based on the above discussion, SuperPATH technology improved patient satisfaction in the early postoperative period.Bodrogi AW et al [31] performed the SuperPATH technique in 17 patients with femoral neck fractures.By clinical follow-up, they found that postoperative analgesia dosage was reduced and the hospital stays were shortened.Jinquan L et al [32] measured the circumference of the thigh after SuperPATH surgery and found that the postoperative degree of edema was signi cantly lower than other small incision surgery, thus reducing the patient pain and other constrained symptoms.
The Harris hip score (HHS) was a widely used synthetical mark of evaluating the hip function and often used to assess the effect of hip replacement.In this meta-analysis, the HHS at week 1, month 1 and months 3 after the operation in the SuperPATH group was higher than those in the conventional replacement group, but there was no signi cant difference after the 6th month.Unfortunately, none of the included articles mentioned speci c details of the HHS score.The author believed that HHS in the initial period was low in the SuperPATH replacement group, indicating a better early functional recovery.The difference in the middle period was not signi cant.But the overall follow-up was shorter, and the long-term e cacy needed observation.Through the collection of postoperative imaging measurements in 66 patients, Della Torre PK et al [2] found the early results in the SuperPATH group were superior to the conventional access group, but the long-term results needed further investigation.
Lewinnek GE et al [33] found that the dislocation rate for cup orientation with anteversion of 15 ± 10 degrees and lateral opening of 40 ± 10 degrees was 1.5 percent, with respect to minimizing the risk of dislocation in the postoperative period.Through the analysis of 2 studies, we found no difference in acetabular abduction angles comparing the SuperPATH group with the conventional group, but simultaneously showed a signi cant difference in acetabular anteversion angles.Archbold HA et al [34] reported that the transverse acetabular ligament was used to determine the position of the acetabular locator.This method is suitable for both conventional and minimally invasive procedures.Therefore, reaming and placement of the acetabular component referring to the transverse acetabular ligament can certainly improve the accuracy of the prosthesis position.Through the analysis of 50 cases for SuperPATH surgery, Rasuli KJ et al [6] also found that reference to acetabular transverse ligament during operation can increase the accuracy of the prosthesis and reduce the rate of dislocation.
For this study, only two studies and 50 patients have enrolled which to some extent restrained the accuracy of our judgment.
This article also had some limitations: (1) Follow-up of each study and some of the evaluation indicators were inconsistent; (2) Lack of detailed score data and incidence of complications were not assessed; (3) We only identi ed the published papers, so unpublished articles may in uence the ultimate result; (4) As the SuperPATH technology was rst reported in 2011, the long-term e cacy and complications still need multi-centers, larger samples for follow-up observation.
The results of this meta-analysis showed that the short and medium-term postoperative hip-related scores of the SuperPATH approach were not signi cantly different from those of the conventional approach.However, the SuperPATH approach on account of shorter incision length, less postoperative transfusion rate, preferable early postoperative VAS and HHS showed that it was superior to the conventional approach.In the meantime, it had the potential advantages of low tissue damage and rapid postoperative recovery which can certainly improve patients' quality of life and satisfaction.

Conclusion
This suggested that SuperPATH was an advantageous approach and inaugurates an era of minimally invasive surgery for hip replacement.But for the limited number of studies and insu cient sample sizes, the conclusion should be treated cautiously.Consequently, larger sample sizes with well-designed RCTs were required to con rm the conclusion.

Figures
Page 9/     Blood loss forest plot analysis comparing the SuperPATH group vs conventional group Transfusion rate forest plot analysis comparing the SuperPATH group vs conventional group Length of stay forest plot analysis comparing the SuperPATH group vs conventional group Anteversion angle plot analysis comparing the SuperPATH group vs conventional group Abduction angle forest plot analysis comparing the SuperPATH group vs conventional group

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Figure 1 Pubmed search strategies

Figure 2 PRISMA
Figure 2 PRISMA study ow diagram

Figure 3 Risk of bias graph Figure 4 Risk of bias summary Figure 5 6
Figure 3 Risk of bias graph

Table 1
Characteristics of the Included Study SuperPATH supercapsular percutaneously assisted total hip, BMI Body mass index, THA Total hip arthroplasty, RCT Randomized controlled trial, CCT Casecontolled trial, NS Not state

Table 2
Newcastle-Ottawa Scale for Risk of Bias Assessment of Cohort Studies Included in the Meta-Analysis Representativeness of exposed cohort, 2 Selection of nonexposed, 3 Ascertainment of exposure, 4 Outcome not present at start, 5 Assessment of outcome, 6 Adequate follow-up length, 7 Adequacy of follow-up score of 0, score of 1, score of 2