Do We Really Need to Repair the Pronator Quadratus in Volar Plating of Distal Radius Fracture (cid:0) A Protocol for Systematic Review and Meta Analysis

Distal radius fracture is a common type of fracture in clinical practice.Over recent years, Volar locking plate internal xation remains the most commonly used surgical treatment method in the treatment of distal radius fractures. To better expose the distal radius and fracture segment, the surgeons have to cut the pronator quadratus(PQ) muscle.However, whether the PQ muscle need to be repaired remains controversial. This study aims to provide a plan to evaluate the clinical ecacy whether to repair the PQ muscle in volar plate xation of distal radius fractures. analysis when a meta-analysis is and


Introduction
Distal radius fractures are responsible for high incidence worldwide, mostly due to the anatomy of distal radius,which is located between cortical and cancellous bone [1,2] .According to relevant research statistics, distal radius fractures are the most common upper limb fractures [3] . Currently, open reduction and volar plate internal xation of distal radius fractures is the best treatment option [4][5][6] .To better place on the deep surface of the PQ muscle, it is necessary to be dissected during the operation [7][8][9] .However, whether to repair the PQ muscle remains controversial.83% (608/753) members of the American Society of Hand Surgery of a previous study recommended that they tried to repair the PQ muscle [10] . The main reason is that it is more bene cial to the recovery of the PQ strength, the stability of the distal radioulnar joint, and avoid the damage caused by the long-term friction between the volar exor tendon and the plate. Another part of the researchs believe that repairing the PQ muscle will further aggravate the ischemic contracture of the muscle, which will eventually affect the range of motion of the forearm [11] .Two studys published in 2013 found that there is no correlation between the repairing of the PQ muscle and the postoperative e cacy and functional recovery of the distal radius fractures [12,13] . The results of another study showed that repairing the PQ muscle can reduce the short-term pain of postoperative patients [14] . Many experiments have compared the effect of repairing and not repairing the PQ muscle on the postoperative e cacy of distal radius fractures [7,[12][13][14] . However, there is still a lack of high-quality systematic reviews. Therefore, this study uses a meta-analysis to systematically evaluate and compare the curative effect and applicability of repairing and not repairing the PQ muscle, so as to provide a basis for orthopedic trauma surgeons to choose appropriate surgical methods. Methods 2.1 Inclusion criteria 2.1.1 Type of study randomized controlled trials (RCTs) and comparative experimental trials will be included in this SR.
Patients should be randomly assigned into with PQ repair and without PQ repair groups. The language of the literature will be limited in English or Chinese.

Participants
All patients were clearly diagnosed as fresh closed distal radius fractures by X-ray or CT. Patients with metachronous fractures, open fractures, or combined with vascular and nerve injury were excluded.

Interventions
Under brachial plexus anesthesia or general anesthesia, the patient is in a supine position, and the radial styloid process is taken from the transverse carpal striae, and an incision extending about 8 cm proximally is exposed from the approach between the exor carpi radialis muscle and the radial artery and vein. The lateral exor carpi tendon is pulled to the ulnar side, and the radial artery and vein are properly pulled to the radial side. Properly bluntly separated along the direction of the muscle bers to expose the distal and proximal ends of the PQ muscle covering the distal radius, and run longitudinally in 1/3 of the radial side [9,13] . The PQ muscle was incised to expose the fractured radius for reduction and internal xation with plate screws. After the internal xation operation is completed, the incision is ushed with saline. In group A, the incised PQ muscle was sutured carefully with absorbable sutures, and then the skin was sutured layer by layer, while in group B, the incised PQ muscle was stretched to cover the steel plate and the tissue was directly sutured layer by layer [12][13][14] .
Postoperative treatment generally does not require plaster xation. After 24, the extension and exion function exercises of the affected metacarpophalangeal joint and interphalangeal joint will be started.
After 2 days, postoperative X-ray photography will be performed to check the fracture reduction and internal xation [7,12] .

Outcomes
The primary outcomes will include the wrist pain intensity measurement via a Visual Analogue Scale (VAS) or a Numerical Rating Scale (NRS) within 2 weeks after surgery.
The range of motion (ROM) of the wrist on the affected side and the disabilities of the Arm, Shoulder and Hand (DASH) score will be collected within 1year after surgery.Secondary results include operation time, intraoperative blood loss, and adverse events (vascular and nerve damage and compartment syndrome).

Date sources
We will search the following databases from establishment to February 2021: PubMed, Cochrane Library, EMBASE, China National Knowledge Infrastructure (CNKI),and Wanfang databases from the beginning to February 2021.

Serarch strategy
Search strategy will follow the Cochrane handbook. The search strategy for PubMed is shownin Table 1, and similar strategies will be built and applied forother electronic databases.The search strategy is listed in Table 1.

Study selection and data extraction
After selecting the study based on the inclusion criteria according to the abovementioned,two independent reviewers will read the full texts of each article to extract pertinent data using a data extraction form. Any disagreements will be solved by discussion or consultation with another researcher. If the primary data is missing,incomplete,or reported in the form of graphs,we will contact the author by email or phone calls for raw data. If the author of the paper has lost the relevant data,or does not agree to provide data,we will give a statistical description in the results section instead of meta-analysis.The research summary of the screening ow chart is shown in Fig. 1.

Quality assessment of included studies
Two independent assessment of risk of bias researchers will individually use the risk of bias (RoB) tool proposed by Cochrane Handbook V.5.2.0 to assess the quality risk of bias (RoB) for randomized controlled trials (RCTs),which included six aspects: (1) Random sequence generation, (2) Allocation concealment, (3) Blinding of patients and personnel, (4) Incomplete outcome data, (5) Selective reporting, (6) Other bias. The RoB in each eld is divided into "Low risk," "High risk," or "Unclear risk." . If the RoB of the research included in the meta-analysis is different, we will conduct a hierarchical analysis based on the RoB to show readers different results under different RoBs.

Subgroup analysis
If heterogeneity is detected, a subgroup analysis will be performed to explore differences in methodological quality, age, and AO fracture classi cation.

Data synthesis and analysis
The meta-analysis in this review will use RevMan 5.3 and Stata 13.0 software. For the outcome index of two categorical variables, relative risk will be used, and for the outcome index of continuous variables, the average difference or standardized average difference will be used, with a con dence interval of 95%. The heterogeneity test will be used for the included studies, and these studies will be tested by the Higgins I 2 test. If there is a low heterogeneity (I 2 ≤25%),a xed-effect model will be used;otherwise, a random effects model (I 2 >25%) will be used [15] . If the I 2 value of the combined results is greater than 75%, we will abandon the meta-analysis and only give a general statistical description of the results [15] .Further analyze the source of heterogeneity and, if necessary, perform subgroup analysis. There are clinical and methodological differences in experimental research. Therefore, this study will choose the random effects model. Finally, a funnel chart will be drawn to assess the publication bias of the literature. If enough research is included, sensitivity analysis will be performed to test the robustness of the results. We will conduct a sensitivity analysis by exclusion. Studies with high risk of bias and outliers that are numerically far away from the rest of the data.

Publication deviation
If the results of the meta-analysis include more than 10 articles, we will use a funnel chart to test whether there is publication bias. If the number of articles included in the study is less than 10, the publication bias is not signi cant.

Quality of evidence
Page 6/10 The quality evidence of the included studies will use the Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach, classi ed evidence as high, moderate, low or very low quality based on considerations of RoB, consistency, directness, precision and publication bias [16] .

Patient and public involvement
Patients and the public were not involved in the design or planning of systematic review protocol.

Discussion
A fracture of the distal radius refers to a fracture within 3 cm of the articular surface of the distal radius [17] . With the aging of the population, the incidence of distal radius fractures in elderly patients is increasing [1,4] . The PQ muscle is close to a quadrilateral and is divided into a deep head and a shallow head [18] . The shallow head plays a major role in the forearm pronation process, the deep head plays a major role in the stability of the distal radioulnar joint, and the deep and shallow head work together to maintain the pronation function of the forearm [19] . Therefore, repairing the PQ muscle should help the functional recovery of patients after internal xation of distal radius fractures.However, some clinical studies compared cases with and without PQ repair after the volar plate of the distal radius, and did not show a signi cant difference in pronation strength. Therefore, there is controversy about repairing or not repairing the PQ muscle. Unfortunately, there is a lack of high-quality systematic reviews or meta-analysis publications, and no systematic and scienti c evaluation of them.
We will conduct this research strictly in accordance with the Cochrane Systematic Review Manual, and report in accordance with the preferred reporting items of the guidelines for systematic review and meta-Analysis. We hope to evaluate and compare the with repaire and without repaire the PQ muscles through a systematic review, and provide some suggestions for its reasonable and effective clinical application.

TRIAL STATUS
► Preliminary searches: started.
► Piloting of the study selection process: started.
► RoB assessment: not started.
► Data analysis: not started Abbreviations Figure 1 Flow diagram of studies identi ed.

Supplementary Files
This is a list of supplementary les associated with this preprint. Click to download. PRISMA2009ChecklistMSWord.doc