Advances in arthroscopic rotator cuff repairs techniques such as single-row, double-row, transosseous-equivalent technique (also called "suture bridge" ) , margin convergence and combined patch augmentation have been extensively adopted in clinic. However, despite the advances in repairing techniques, rather high re-tear incidence especially for large to massive tears have been reported from 20% to 94% after rotator cuff repairs. Considering that rotator cuff re-tear remain a substantial implication of functional outcomes after surgical repairing, biologically based strategies to improve the quality of tendon tissue after surgical reconstruction have gained increasing interest over the last several years. Stem cells, growth factors and other tissue engineering methods are increasingly being used to improve rotator cuff healing after repair. Mesenchymal stem cells (MSCs) have been suggested to promote rotator cuff healing and should be promoted clinically. Bone marrow stimulation technologies such as micro-fracture technology and multi-channel technology have also attracted much attention. This technology is simple, direct and inexpensive, which can provide sufficient MSCs for local tendon healing and promote the occurrence of microvascularization. This technique involves perforating the musculoskeletal joint, such as the foot print area of rotator cuff, into the cartilage and locally releasing BM-MSCs to facilitate healing. In a preclinical biomechanical study, the terminal failure load of rotator cuff was significantly increased in the BMS group compared with that in the control group. Animal studies have also shown that stem cells can infiltrate into the footprint area and ultimately strengthen the rotator cuff after repair. Hernigou et al. performed a case control study comparing patients who received simple single-row repair and enhanced repair with stem cells. The stem cell group had 100% intact repair at 6 months compared to 67% of control group, and at 10 years, the rate was 87% versus 44%. Several clinical studies and meta-analyses have found that bone marrow stimulation can definitely reduce the rate of re-tear after rotator cuff repair compared with conventional repair.

To evaluate the role of bone marrow stimulation technique in the improvement of rotator cuff healing and function.

The Cochrane Library, PubMed, Medline, Embase, CNKI, VIP, Wanfang and CBM and other databases were retrieved on the comparative studies of using bone marrow stimulation technology and simple rotator cuff repair, including clinical randomized controlled and retrospective cohort studies. manual search of The references of included studies were manually retrieved. The index data from each study was extracted, including overall re-tear rate, re-tear rate of large rotator cuff tears, postoperative shoulder joint mobility, visual analog scale (VAS) score, Constant-Murley score (CMS) , University of California, Los Angeles shoulder rating scale (UCLA) , American shoulder and elbow surgeons score (ASES) , and disabilities of the arm, shoulder, and hand questionnaire (DASH) . The Revman 5.3 software was used for analysis and process.

A total of 2 randomized controlled studies and 6 retrospective cohort studies were included in the Meta-analysis. Two uncontrolled retrospective studies and 2 uncontrolled retrospective studies and previous 8 studies were included in the systematic review. The meta-analysis only included the first 8 articles with 641 patients. The results of meta-analysis show that, compared with simple rotator cuff repair, rotator cuff repair combined with bone marrow stimulation technology can significantly improve the overall healing effect of rotator cuff [OR = 0.42, 95% CI (0.28, 0.63) , P< 0.0001] . Meanwhile, the re-tear rate of large to massive rotator cuff tear after repair was also significantly reduced [OR = 0.28, 95% CI (0.13, 0.58) , P = 0.0007] . In terms of shoulder VAS score [SMD = -0.63, 95% CI (-1.40, 0.14) , P = 0.11] , range of motion (ROM) external rotation [SMD = 0.05, 95% CI (-0.22, 0.32) , P = 0.70] ; anteflexion [SMD = 0.10, 95% CI (-0.17, 0.37) , P = 0.47] , shoulder function CMS score [SMD = 0.12, 95% CI (-0.09, 0.32) , P = 0.26] , UCLA score [SMD = -0.04, 95% CI (-0.29, 0.21) , P = 0.76] , ASES score [SMD = -0.06, 95% CI (-0.33, 0.21) , P = 0.67] , and DASH score [SMD = -0.15, 95% CI (-0.43, 0.13) , P = 0.29] , there was no statistical difference.

Compared with simple rotator cuff repair, rotator cuff repair combined with bone marrow stimulation technology can significantly improve the rotator cuff repair capability. It is particularly noteworthy that this technology can promote the healing of large to massive rotator cuff tear, and there was no significant difference in postoperative shoulder pain, ROM and function.

Proximal humeral fractures are one of the most common fractures, accounting for 4%-5% of total body fractures, and their incidence increases with age. Neer classification is the most widely used classification system, and it divides the proximal humeral fracture into four parts: humeral head, greater tuberosity, lesser tuberosity and humeral shaft. According to the fracture displacement (>1 cm) and angulation (>45°) , proximal humeral fracture is divided into 1 to 4-part. For non-displaced or slightly displaced proximal humeral fractures, conservative treatment can usually achieve satisfactory clinical outcomes. However, the treatment of complex proximal humeral fractures (Neer 3 or 4-part fractures and fracture-dislocations) is more difficult. Conservative treatment, locking plate and humeral head replacement are the most commonly used treatments in clinic, but there is still debate about their clinical efficacy. Conservative treatment mainly involves proper manual reduction and fixation by suspension or other means. It is theoretically difficult to perform satisfactory fracture reduction and reliable fixation, and may bring a relatively high rate of malunion and other complications. Neer et al, first proposed humeral head replacement for treatment of displaced 3 or 4-part fractures and fracture-dislocations, and reported higher patient satisfaction. However, humeral head replacement is more traumatic with complex surgical technique, long postoperative recovery time and more complications, which often leads to poor function. Later studies have reported poor functional results as well. Locking plate fixation is also a classic treatment for displaced proximal humeral fractures. Plate with angle-stabilized screws is used for fracture fixation as a whole. Theoretically, complications such as internal fixation failure and screw penetration can be significantly reduced. Currently, there have been many systematic reviews on the proximal humeral fractures, but the included literatures are mostly retrospective studies with low levels of evidence. Objective This study conducted a meta-analysis of currently published randomized controlled trials to obtain a higher level of evidence for clinical guidelines in the treatment of complex proximal humeral fractures in the elderly.

The randomized controlled trials that met the inclusive criteria and reported functional scores and complications were searched on Pubmed, EMBASE and Cochrane General Register of Controlled Trials. The evidence levels of literatures were evaluated for the extraction of functional scores and complications. Metaman 5.0 software was used for meta-analysis.

A total of 4 randomized controlled trials involving 215 patients were included in the study. Two of the literatures (105 patients) compared the overall and group Constant scores and complications between conservative treatment and humeral head replacement of Neer part-4 proximal humeral fractures. The meta-analysis showed a higher short-term overall Constant score (WMD =5.69, 95% CI: 0.34-11.03, P=0.04) of conservative treatment compared with humeral head replacement for Neer part-4 proximal humeral fractures. The VAS score (WMD =-2.75, 95% CI: -4.45- -1.04, P= 0.002) was significantly improved one year after humeral head replacement, but the there was no significant difference compared with conservative treatment (WMD =-2.46 , 95% CI: -8.88-3.96, P=0.45) . Another two literatures (110 patients) compared Constant scores and complications between conservative treatment and locking plate fixation of Neer part-3 and part-4 proximal humeral fractures. The meta-analysis showed no significant difference in the improvement of functional scores and complications between them. One of the studies showed that for Neer part-3 fractures, locking plate fixation may improve the overall functional score of the patient.

The functional score was higher for conservative treatment of Neer part-4 fractures in the short term. The humeral head replacement can improve long-term pain, but it cannot improve the overall functional score. Locking plate fixation may improve overall functional scores in patients with Neer part-3 fractures.