***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Controversy exists regarding the optimal technique for arthroscopic rotator cuff repair . The purpose of this multicenter , r and omized , double-blind controlled study was to compare the functional outcomes and healing rates after use of single-row and double-row suture techniques for repair of the rotator cuff . METHODS Ninety patients undergoing arthroscopic rotator cuff repair  were r and omized to receive either a single-row or a double-row repair . The primary objective was to compare the Western Ontario rotator cuff index ( WORC ) score at twenty-four months . Secondary objectives included comparison of the constant and american shoulder and elbow surgeons ( ASES ) scores and strength between groups . Anatomical outcomes were assessed with magnetic resonance imaging ( MRI ) or ultrasonography to determine the postoperative healing rates . RESULTS Baseline demographic data including age ( p = 0.29 ) , sex ( p = 0.68 ) , affected side ( p = 0.39 ) , and rotator cuff tear size ( p = 0.28 ) did not differ between groups . The WORC score did not differ significantly between groups at any time point ( p = 0.48 at baseline , p = 0.089 at three months , p = 0.52 at six months , p = 0.83 at twelve months , and p = 0.60 at twenty-four months ) . The WORC score at each postoperative time point was significantly better than the baseline value . The Constant score , ASES score , and strength did not differ significantly between groups at any time point . Logistic regression analysis demonstrated that a smaller initial tear size and double-row fixation were associated with higher healing rates . CONCLUSIONS No significant differences in functional or quality -of-life outcomes were identified between single-row and double-row fixation techniques . A smaller initial tear size and a double-row fixation technique were associated with higher healing rates as assessed with ultrasonography or MRI . LEVEL OF EVIDENCE Therapeutic level I. See Instructions for Authors for a complete description of levels of evidence Background Recurrent defects after open and arthroscopic rotator cuff repair are common . Double-row repair techniques may improve initial fixation and quality of rotator cuff repair .  Purpose To evaluate the load to failure , cyclic displacement , and anatomical footprint of 4 arthroscopic rotator cuff repair techniques .  Hypothesis Double-row suture anchor repair would have superior structural properties and would create a larger footprint compared to single-row repair . Study Design Controlled laboratory study . Methods Twenty fresh-frozen cadaveric shoulders were r and omly assigned to 4 arthroscopic repair techniques . The repair was performed as either a single-row technique or 1 of 3 double-row techniques : diamond , mattress double anchor , or modified mattress double anchor . Angle of loading , anchor type , bone mineral density , anchor distribution , angle of anchor insertion , arthroscopic technique , and suture type and size were all controlled . Footprint length and width were quantified before and after repair . Displacement with cyclic loading and load to failure were determined . Results There were no differences in load to failure and displacement with cyclic loading between the single-row repair and each double-row repair . All repair groups demonstrated load to failure greater than 250 N. A significantly greater supraspinatus footprint width was seen with double-row techniques compared to single-row repair . Conclusions The single-row repair technique was similar to the double-row techniques in load to failure , cyclic displacement , and gap formation . The double-row anchor repairs consistently restored a larger footprint than did the single-row method . Clinical Relevance The arthroscopic techniques studied have strong structural properties that approached the reported performance of open repair techniques . Double-row techniques provide a larger footprint width ; although not addressed by this study , such a factor may improve the biological quality of repair Purpose The purpose of this study was to compare arthroscopic rotator cuff repair with single-row and double-row techniques because research has demonstrated the superiority of double-row repair from a biological and mechanical point of view but there is no evidence of clinical superiority . Methods A total of 160 patients with a full-thickness rotator cuff tear underwent arthroscopic repair with suture anchors .  They were r and omised into two groups of 80 patients according to the repair technique : single-row ( group 1 ) and double-row ( group 2 ) . Results were evaluated by use of the University of California , Los Angeles ( UCLA ) , American Shoulder and Elbow Surgeons ( ASES ) and Constant question naires , the Shoulder Strength Index ( SSI ) and range of motion . Follow-up time was two years . Magnetic resonance imaging ( MRI ) studies were performed on each shoulder preoperatively and two years after repair . Results One hundred per cent of the patients were followed up . All measurements showed significant improvement compared with the preoperative status . The UCLA score showed significant improvement in group 2 . In over 30-mm tears UCLA and ASES showed significant differences . SSI showed significant improvement in group 2 . Range of motion showed significant improvements in flexion and abduction in group 2 . In under 30-mm tears group 2 showed also significant improvement in internal and external rotation . In MRI studies there were no significant differences . Conclusions At two years follow-up the double-row repair technique showed a significant difference in clinical outcome compared with single-row repair and this was even more significative in over 30-mm tears . No MRI differences were observed PURPOSE The purpose of this study was to determine biomechanical differences in cyclic elongation and ultimate strength between double-row rotator cuff repair  and single-row repair  for partial rotator cuff repairs . METHODS We r and omly assigned 18 immature bovine specimens ( aged 12 to 16 weeks ) to 3 repair groups ( 6 per group ) . A 1 x 2-cm defect was created at the infraspinatus tendon insertion site . Two suture anchors were implanted 1 cm apart at the anatomic insertion area for the lateral row . Two suture anchors were implanted 1 cm medial to the lateral row and 1 cm apart from each other for the medial row . Repair groups were constructed as follows : single-row repair with double-loaded suture anchors ( group 1 ) , double-row repair with single-loaded medial row and double-loaded lateral row ( group 2 ) , and double-row repair with single-loaded medial row and single-loaded lateral row ( group 3 ) . Specimens were cyclically loaded from 10 N to 90 N for 500 cycles and then loaded at 0.5 mm/s to failure . Data for cyclic elongation , with loads at 3 mm , 5 mm , and 10 mm , were analyzed via a 1-way analysis of variance ( P < .05 ) . RESULTS There were no significant differences for peak elongation after cyclic loading between groups . There were no significant differences between repair groups for loads at 3 mm , 5 mm , and 10 mm of elongation . Constructs typically failed by knot slippage ( 83 % ) , with a single sample having tendon-suture failure ( 17 % ) . CONCLUSIONS Double-row repair did not show a biomechanical advantage compared with single-row repair . With this result in mind , the theoretic advantage of a potentially larger footprint must be balanced against the added surgical time , complexity , and cost of double-row repair . CLINICAL RELEVANCE Arthroscopic surgeons should choose the best form of fixation for a given patient , without undue emphasis on single-row repair versus double-row repair . The clinical and biologic impact of footprint restoration was not addressed in this study BACKGROUND The purpose s of this study were to identify changes in tear dimensions , shoulder function , and glenohumeral kinematics when an asymptomatic rotator cuff tear becomes painful and to identify characteristics of individuals who develop pain compared with those who remain asymptomatic . METHODS A cohort of 195 subjects with an asymptomatic rotator cuff tear was prospect ively monitored for pain development and examined annually for changes in various parameters such as tear size , fatty degeneration of the rotator cuff muscle , glenohumeral kinematics , and shoulder function . Forty-four subjects were found to have developed new pain , and the parameters before and after pain development were compared . The forty-four subjects were then compared with a group of  fifty-five subjects who remained asymptomatic over a two-year period . RESULTS With pain development , the size of a full-thickness rotator cuff tear increased significantly , with 18 % of the full-thickness tears showing an increase of > 5 mm , and 40 % of the partial-thickness tears had progressed to a full-thickness tear . In comparison with the assessment s made before the onset of pain , the American Shoulder and Elbow Surgeons scores for shoulder function were significantly decreased and all measures of shoulder range of motion were decreased except for external rotation at 90 ° of abduction . There was an increase in compensatory scapulothoracic motion in relation to the glenohumeral motion during early shoulder abduction with pain development . No significant changes were found in external rotation strength or muscular fatty degeneration . Compared with the subjects who remained asymptomatic , the subjects who developed pain were found to have significantly larger tears at the time of initial enrollment . CONCLUSIONS Pain development in shoulders with an asymptomatic rotator cuff tear is associated with an increase in tear size . Larger tears are more likely to develop pain in the short term than are smaller tears . Further research is warranted to investigate the role of prophylactic treatment of asymptomatic shoulders to avoid the development of pain and loss of shoulder function Background Double-row arthroscopic rotator cuff repair has become more popular , and some studies have shown better footprint coverage and improved biomechanics of the repair . Hypothesis Double-row rotator cuff repair leads to superior cuff integrity and early clinical results compared with single-row repair . Study Design R and omized controlled trial ; Level of evidence , 1 . Methods Forty patients were r and omized to either single-row or double-row rotator cuff repair at the time of surgical intervention . Patients were followed with clinical measures ( UCLA , Constant , WORC , SANE , ASES , as well as range of motion , internal rotation strength , and external rotation strength ) . Magnetic resonance imaging ( MRI ) studies were performed on each shoulder preoperatively , 6 weeks , 3 months , and 1 year after repair . Results Mean anteroposterior tear size by MRI was 1.8 cm . A mean of 2.25 anchors for single row ( SR ) and 3.2 for double row ( DR ) were used . There were 2 retears at 1 year in each group . There were 2 additional cases that had severe thinning in the DR repair group at 1 year . The MRI measurements of footprint coverage , tendon thickness , and tendon signal showed no significant differences between the 2 repair groups . At 1 year , there were no differences in any of the postoperative measures of motion or strength . At 1 year , mean WORC ( SR , 84.8 ; DR , 87.9 ) , Constant ( SR , 77.8 ; DR , 74.4 ) , ASES ( SR , 85.9 ; DR , 85.5 ) , UCLA ( SR , 28.6 ; DR , 29.5 ) , and SANE ( SR , 90.9 ; DR , 89.9 ) scores showed no significant differences between groups . Conclusions No clinical or MRI differences were seen between patients repaired with a SR or DR technique BACKGROUND Recent studies have shown that  arthroscopic rotator cuff repairs  can have higher rates of failure than do open repairs . Current methods of rotator cuff repair have been limited to single-row fixation of simple and horizontal stitches , which is very different from open repairs . The objective of this study was to compare the initial cyclic loading and load-to-failure properties of double-row fixation with those of three commonly used single-row techniques . METHODS Ten paired human supraspinatus tendons were split in half , yielding four tendons per cadaver . The bone mineral content at the greater tuberosity was assessed . Four stitch configurations ( two-simple , massive cuff , arthroscopic Mason-Allen , and double-row fixation ) were r and omized and tested on each set of tendons . Specimens were cyclically loaded between 5 and 100 N at 0.25 Hz for fifty cycles and then loaded to failure under displacement control at 1 mm/sec . Conditioning elongation , peak-to-peak elongation , ultimate tensile load , and stiffness were measured with use of a three-dimensional tracking system and compared , and the failure type ( suture or anchor pull-out ) was recorded . RESULTS No significant differences were found among the stitches with respect to conditioning elongation . The mean peak-to-peak elongation ( and st and ard error of the mean ) was significantly lower for the massive cuff ( 1.1 + /- 0.1 mm ) and double-row stitches ( 1.1 + /- 0.1 mm ) than for the arthroscopic Mason-Allen stitch ( 1.5 + /- 0.2 mm ) ( p < 0.05 ) . The ultimate tensile load was significantly higher for double-row fixation ( 287 + /- 24 N ) than for all of the single-row fixations ( p < 0.05 ) . Additionally , the massive cuff stitch ( 250 + /- 21 N ) was found to have a significantly higher ultimate tensile load than the two-simple ( 191 + /- 18 N ) and arthroscopic Mason-Allen ( 212 + /- 21 N ) stitches ( p < 0.05 ) . No significant differences in stiffness were found among the stitches . Failure mechanisms were similar for all stitches . Rotator cuff repairs in the anterior half of the greater tuberosity had a significantly lower peak-to-peak elongation and higher ultimate tensile strength than did repairs on the posterior half . CONCLUSIONS In this in vitro cadaver study , double-row fixation had a significantly higher ultimate tensile load than the three types 
    Output:
    
Single-row repairs result ed in significantly higher re-tear rates compared with double-row repairs , especially with regard to partial-thickness re-tears .
However , there were no detectable differences in improvement in outcomes scores between single-row and double-row repairs