| Background: Massive and irreparable rotator cuff tears mainly refer to rotator cuff tears with a diameter of more than 5 cm in the anterior-posterior direction,inside and outside direction,or in two or more rotator cuff tendons.When the sagittal and coronal images in magnetic resonance imaging,shows the tendon rupture and retraction that lead to a defect of more than 2 cm × 2 cm or the ruptured tendon retracted to the glenoid margin,and when the MRI sagittal images show at least two-thirds of the greater tuberosity exposed,a massive and irreparable rotator cuff tear is involved.The formation of massive and irreparable rotator cuff tear is often accompanied by the aggravation of muscle fat infiltration and muscle atrophy.Consequently,the tendon is hardly pulled back to the footprint area for repair after the complete release of the tendon during surgery,or it is easy to tear again after repair,becoming a massive and irreparable rotator cuff tear.The treatment for massive and irreparable rotator cuff tear is extremely difficult,and the failure rate of surgery is approximately 94%,which seriously affects the recovery of shoulder joint function.Based on the development of related research,the superior capsule reconstruction plays an important role in stabilizing the humeral head.Reconstruction of the superior capsule can effectively treat the massive and irreparable rotator cuff tear that cannot be repaired and restore the function of the shoulder joint.Fascia lata or biological patch is the traditional graft material used in the reconstruction of the superior capsule,and it is currently the most thoroughly studied and clinically applied standardized surgical method.However,the surgical process is complex,and the learning curve is long,making the process difficult.In recent years,some scholars introduced the use of biceps tendon or hamstring tendon to reconstruct the superior capsule of shoulder unconventionally.Clinical studies confirmed that the treatment effect is satisfactory,and the method greatly simplifies the process and reduces the operation difficulty.However,it has some disadvantages.Various methods of superior capsule reconstruction were analyzed after summarizing,we designed a new kind of autologous hamstring tendons in the superior capsule reconstruction to treat the massive and irreparable rotator cuff tear,biomechanical tests confirmed by finite element analysis on its effectiveness,and observe its clinical effect in clinical application.Objective:First study: This study aimed to evaluate the biomechanics of intact shoulder model,supraspinatus defect model,hamstring tendon and fascia lata graft for the reconstruction of the superior capsule of shoulder joint by finite element analysis.Subsequently,it aimed to verify the effectiveness of hamstring tendon reconstruction of the upper joint capsule.Second study: This study aimed to investigate the clinical outcome and radiographic findings after arthroscopic superior capsule reconstruction with hamstring tendon for irreparable rotator cuff tears.Methods:First study: The Dicom CT and MRI images of the left shoulder of a healthy male volunteer were used to establish the shoulder models of intact model,supraspinatus defect model,and superior capsule reconstruction with hamstring tendon and with the fascia lata model by finite element analysis.At the fixed medial edge of the scapula and the sternal end of the clavicle,the anatomical positions were simulated when the shoulder was oriented at 0°–30° abduction,adduction,flexion,extension,external rotation,and internal rotation.The upward displacement distance of humeral head center and the stress distribution of grafts and rotator cuff muscles were observed.Second study: From Dec 2019 to Jan 2021,15 patients(9 males and 6 females,7 left arms and 8 right arms,age range: from 51–69)with irreparable rotator cuff tears underwent superior capsule reconstruction with hamstring tendon in the Department of Sports Medicine and Arthroscopic Surgery in The First Affiliated Hospital of Anhui Medical University.In the operation,semitendinosus tendon was harvested and folded into three strands to form a transplanted tendon with a length of 9.0–9.5 cm and diameter of more than 6 mm.The median part of the tendon was fixed using two suture anchors inserted into the superior glenoid at the 11:30 and 1 o'clock(Right shoulder)or 11 and12:30 o'clock(Left shoulder)position.The ends of the tendon were fixed medially by two suture anchors at the anterior and posterior edge of the supraspinatus tendon insertion point and lateral side of the cartilage of the humeral heads and sequentially fixed together to the footprint of greater tuberosity by a Pushlock anchor.Finally,we added side-to-side sutures between the graft and the infraspinatus tendon,residual supraspinatus tendon,and coracohumeral ligament to improve force coupling.The arthroscopic long head of biceps suprapectoral tenodesis and acromioplasty also underwent in the surgery.All patients were followed up for at least 12 months,and the demographic characteristics of each patient were recorded in detail.Moreover,clinical examinations of the patients such as shoulder active range of motion,A-H distance,VAS scores,ASES scores,UCLA scores,and Constant scores,were investigated prior to surgery and at 3,6,and 12 months after surgery and the latest follow-up.Magnetic resonance imaging was performed preoperatively and at 6 and 12 months post-operative and the latest follow-up for observing tendon healing situation.Post-operative complications were also comprehensively investigated.Results:First study: When the intact shoulder model abduction to 30°,the maximum stress of supraspinatus,subscapularis,infraspinatus,and teres minor were 4.23,15.84,16.20,and3.23 MPa,the average supraspinatus stress was 2.16 MPa,the vertical displacement of the apex of the greater tubercle was 17.64 mm,and the vertical displacement of the center of the humeral head was 3.83 mm.In the supraspinatus defect model,the maximum stress of subscapularis,infraspinatus,and teres minor were 15.9,29.67,and 7.96 MPa,respectively,the vertical displacement of the apex of the greater tubercle was 18.71 mm,and the vertical displacement of the center of the humeral head was 6.51 mm.In the superior capsule reconstruction with hamstring tendon model,the maximum stress of tendon graft,subscapularis,infraspinatus,and teres minor were 167.87,17.98,14.21,and4.05 MPa,the average supraspinatus stress was 24.11 MPa,the vertical displacement of the apex of the greater tubercle was 17.81 mm,and the vertical displacement of the center of the humeral head was 4.87 mm.In the superior capsule reconstruction with fascia lata model,the maximum stress of tendon graft,subscapularis,infraspinatus,and teres minor were 103.7,18.54,13.28,and 2.79 MPa,the average supraspinatus stress was 25.36 MPa,the vertical displacement of the apex of the greater tubercle was 15.81 mm,and the vertical displacement of the center of the humeral head was 4.27 mm.The vertical displacement of the center of the humeral head remarkably decreased in the superior capsule reconstruction with hamstring tendon or fascia lata model compared with supraspinatus defect model,and the maximum stresses of infraspinatus and teres minor decreased sequentially and tended to be intact shoulder model.The maximum stress of hamstring tendon graft was larger than the fascia lata,but almost no difference was observed in the average stress between them.Second study: The average follow-up was 18.53±4.13 months after surgery.The mean A-H distance increased from 5.03±0.6 mm pre-operatively to 8.19±0.49 mm postoperatively(P<0.05).The VAS score decreased from 6.33±1.35 points pre-operatively to1.93±0.93,0.33±0.70,and 0.4±0.70 points at 1 month,1 year after surgery,and at the latest follow up(P<0.05).The mean active elevation increased from 100.00°±46.62° to158.00°±12.22°,abduction increased form 48.33°±26.50° to 85.67°±22.43°,and external rotation increased form 16.67°±9.25° to 31.33°±3.40°(P<0.05).The mean ASES,UCLA,and constant scores increased form 42.89±14.13,15.40±4.94,and 56.80±13.93 points pre-operatively to 90.09±5.30,31.60±3.24,and 88.93±6.58 points at the latest follow-up(P<0.05).A patient received revision surgery because of a traffic accident 20 months after operation,resulting in shoulder pain and dysfunction and invalid tendon on MRI imaging.The data of this patient at the follow-up of 1 year and 18 months after operation were not excluded from this group.All tendons in other patients were intact,and no further arthrophlogosis or muscle atrophy was observed on the follow-up MRI.Conclusions:First study: Superior capsule reconstruction with hamstring tendon or fascia lata can provide favorable static stability and stress distribution,thus providing a theoretical basis for the clinical study.Second study: Arthroscopic superior capsule reconstruction with hamstring tendon for irreparable rotator cuff tears was a useful alternative treatment that remarkably decreased pain,improved the function of the shoulder,and did not show any further arthrophlogosis or muscle atrophy and increased A-H distance. |
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