Tendon-to-bone pressure distributions at a repaired rotator cuff footprint using transosseous suture and suture anchor fixation techniques

BACKGROUND: Interface contact pressure between the tendon and bone has been shown to influence healing. This study evaluates the interface pressure of the rotator cuff tendon to the greater tuberosity for different rotator cuff repair techniques. HYPOTHESIS: The transosseous tunnel rotator cuff repair technique provides larger pressure distributions over a defined insertion footprint than do suture anchor techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Simulated rotator cuff tears over a 1 x 2-cm infraspinatus insertion footprint were created in 25 bovine shoulders. A transosseous tunnel simple suture technique (n = 8), suture anchor simple technique (n = 9), and suture anchor mattress technique (n = 8) were used for repair. Pressurized contact areas and mean pressures of the repaired tendon against the tuberosity were determined using pressure-sensitive film placed between the tendon and the tuberosity. RESULTS: The mean contact area between the tendon and tuberosity insertion footprint was significantly greater for the transosseous technique (67.7 +/- 5.8 mm(2)) compared with the suture anchor simple (34.1 +/- 9.4 mm(2)) and suture anchor mattress (26.0 +/- 5.3 mm(2)) techniques (P < .05). The mean interface pressure exerted over the footprint by the tendon was also greater for the transosseous technique (0.32 +/- 0.05 MPa) compared with the suture anchor simple (0.26 +/- 0.04 MPa) and suture anchor mattress (0.24 +/- 0.02 MPa) techniques (P < .05). CONCLUSION: The transosseous tunnel rotator cuff repair technique creates significantly more contact and greater overall pressure distribution over a defined footprint when compared with suture anchor techniques. CLINICAL RELEVANCE: Stronger and faster rotator cuff healing may be expected when beneficial pressure distributions exist between the repaired rotator cuff and its insertion footprint. Tendon-to-tuberosity pressure and contact characteristics should be considered in the development of improved open and arthroscopic rotator cuff repair techniques.     

Stress distribution in the supraspinatus tendon after tendon repair: suture anchors versus transosseous suture fixation

BACKGROUND: The stress concentration at the site of supraspinatus tendon repair, either by suture anchor fixation or by transosseous suture fixation, has not been fully clarified. HYPOTHESIS: Suture anchor fixation showed higher stress concentrations in the tendon than did transosseous suture fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Three finite element models were developed based on a previously published model of normal supraspinatus tendon (0 degrees abduction). Single-row fixation, double-row fixation, and transosseous suture fixation were simulated. A tensile force was applied to the proximal end of the supraspinatus tendon to simulate its contraction force. RESULTS: In the single-row model, the stress appeared from the site of the anchor and extended into the proximal tendon. The highest stress concentration was observed on the bursal surface of the tendon. The double-row model showed a similar pattern to the single-row model except that the stress concentration was observed only around the medial anchor. In the transosseous model, the stress appeared from the attachment site to a bony trough, which extended proximally into the tendon substance. No significant stress concentration was observed inside the tendon. CONCLUSION: Both single-row and double-row fixations showed higher stress concentration inside the tendon than did transosseous suture fixation. CLINICAL RELEVANCE: A high stress concentration might be a cause of the rerupture often observed after arthroscopic cuff repair using suture anchors.     

异体骨锚钉双排固定法修复肩袖损伤

目的 探讨异体皮质骨锚钉双排固定法修复肩袖损伤的价值.方法 关节镜监视下,采用同种异体皮质骨锚钉双排同定法修复肩袖损伤16例.其中男10例,女6例;年龄32～58岁,平均44岁.按Bigliani肩袖损伤分类法,小撕裂6例,中度撕裂8例,大撕裂2例.关节镜下肩袖清理和肩峰成形后,采用带线异体骨锚钉植入肱骨大结节肩袖附着处,双根缝线垂直褥式缝合冈上肌腱,分别打结固定后,将缝线交叉牵引到在肱骨大结节预制的骨道处,将缝线穿入另一个骨锚钉孔内并击入骨道内.4根缝线交叉呈网状覆盖撕裂的冈上肌腱由骨锚钉固定.根据撕裂创面大小决定骨锚钉植入数量.结果 所有患者术后得到随访,时间6～23个月,平均14个月.术后疼痛症状均消失,肩关节功能采用美国加州洛杉矶大学(UCLA)功能评分标准评估,术前(20.5±5.6)分,术后(33.4±5.8)分.优10例,良5例,可1例.术后肩关节稳定性良好,无锚钉拔出和损伤复发.结论 异体骨锚钉双排同定法修复肩袖损伤,镜下手术操作方便,骨锚钉嵌入固定牢靠,增加肩袖组织与骨创面的接触面积,有利于肩袖愈合.骨锚钉生物固定,无异物存留,价格低廉.     

Biomechanical comparison of a single-row versus double-row suture anchor technique for rotator cuff repair

BACKGROUND: Reestablishment of the native footprint during rotator cuff repair has been suggested as an important criterion for optimizing healing potential and fixation strength. HYPOTHESIS: A double-row rotator cuff footprint repair will demonstrate superior biomechanical properties compared with a single-row repair. STUDY DESIGN: Controlled laboratory study. METHODS: In 9 matched pairs of fresh-frozen cadaveric shoulders, the supraspinatus tendon from 1 shoulder was repaired with a double-row suture anchor technique: 2 medial anchors with horizontal mattress sutures and 2 lateral anchors with simple sutures. The tendon from the contralateral shoulder was repaired using a single lateral row of 2 anchors with simple sutures. Each specimen underwent cyclic loading from 10 to 180 N for 200 cycles, followed by tensile testing to failure. Gap formation and strain over the footprint area were measured using a video digitizing system; stiffness and failure load were determined from testing machine data. RESULTS: Gap formation for the double-row repair was significantly smaller (P < .05) when compared with the single-row repair for the first cycle (1.67 +/- 0.75 mm vs 3.10 +/- 1.67 mm, respectively) and the last cycle (3.58 +/- 2.59 mm vs 7.64 +/- 3.74 mm, respectively). The initial strain over the footprint area for the double-row repair was nearly one third (P < .05) the strain of the single-row repair. Adding a medial row of anchors increased the stiffness of the repair by 46% and the ultimate failure load by 48% (P < .05). CONCLUSION: Footprint reconstruction of the rotator cuff using a double-row repair improved initial strength and stiffness and decreased gap formation and strain over the footprint when compared with a single-row repair. CLINICAL RELEVANCE: To achieve maximal initial fixation strength and minimal gap formation for rotator cuff repair, reconstructing the footprint attachment with 2 rows of suture anchors should be considered.     

Arthroscopic transosseous (anchorless) rotator cuff repair

The traditional open transosseous rotator cuff repair gives excellent results for the fixation of tendon to bone and has represented the gold standard for rotator cuff surgery with excellent long-term results. In the last few years, different arthroscopic techniques using suture anchors have been developed to increase the tendon-bone contact area in an attempt to reconstitute a more anatomic configuration of the rotator cuff footprint while providing a better environment for tendon healing. However, the anchor-based techniques have still not replicated the traditional open transosseous repair. A surgical technique that allows surgeons to perform a standardized arthroscopic transosseous (anchor free) repair of rotator cuff tears using a new disposable device is described. With this system, it is possible to perform a transosseous technique in a reproducible fashion. This novel technique combines the clinical advantages of minimally invasive arthroscopic surgery and the biomechanical advantages of open transosseous procedures. LEVEL OF EVIDENCE: V.     

Transosseous arthroscopic repair of partial articular-surface supraspinatus tendon tears

Partial articular-surface tendon avulsion (PASTA) lesions of the supraspinatus muscle represent a common cause for shoulder impairment and a preceding pathology for full-thickness tendon tears. Arthroscopic tendon repair is a possible surgical method of treatment. The purposes of cuff repair are anatomical tendon healing, prevention of tear size progression to completion and reduction of shoulder pain. In this report, we describe a transtendon arthroscopic technique of transosseous refixation of articular-side partial tears leaving the bursal layer of the supraspinatus tendon intact. A curved hollow needle is used to perform an all arthroscopic transosseous mattress suture. Thus, anatomical tendon-to-bone contact of the rotator cuff to the footprint is restored. Preliminary clinical results of 16 patients are convincing with significant pain relief and functional improvement.     

Arthroscopic single-row versus double-row suture anchor rotator cuff repair

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 randomly 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.     

Contact area, contact pressure, and pressure patterns of the tendon-bone interface after rotator cuff repair

BACKGROUND: The contact pressure and contact area at the tendon-bone interface after the most commonly used rotator cuff repair methods have not been investigated. HYPOTHESIS: There are no significant differences among the transosseous, the single-row suture anchor, and the double-row suture anchor techniques in terms of contact pressure, contact area, and pressure patterns at the tendon-bone interface. STUDY DESIGN: Controlled laboratory study. METHODS: After creating a full-thickness supraspinatus tendon tear in 10 cadaveric shoulder specimens, we inserted pressure-sensitive film between the tendon stump and the bone, and we repaired the tear by (1) transosseous, (2) single-row suture anchor, and (3) double-row suture anchor techniques. RESULTS: The contact area of the double-row technique was 42% greater than that of the transosseous technique (P < .0001) and 60% greater than that of the single-row technique. The contact area of the transosseous technique was 31% greater than that of the single-row technique (P = .0015). The average pressures of the single-row and double-row techniques were 18% (P = .014) and 16% (P = .03) greater, respectively, than that of the transosseous technique, but there was no significant difference between the single-row and double-row techniques (P = .915). CONCLUSIONS: The double-row technique produced the greatest contact area and the second-highest contact pressure, whereas the single-row technique created the highest contact pressure and the least contact area. The transosseous technique produced the second-greatest contact area and the least contact pressure. CLINICAL RELEVANCE: The double-row suture anchor technique and the transosseous technique may provide a better environment for tendon healing.     

Complications of rotator cuff surgery in which bioabsorbable anchors are used

OBJECTIVE: This study assessed the utility of MRI in patients with new or persistent pain after surgery with bioabsorbable rotator cuff anchors. SUBJECTS AND METHODS. Three musculoskeletal radiologists prospectively reviewed MRIs of 30 patients with pain after rotator cuff repair with fixation by rotator cuff anchors. Each radiologist described the location of the rotator cuff anchors and whether the supraspinatus tendon was intact or not. MRI findings were correlated with second-look arthroscopy. Consensus MRI interpretations by the three radiologists were obtained retrospectively. RESULTS: Of the 30 patients, nine had dislodgement of the rotator cuff anchors from the humeral head along with a full-thickness supraspinatus tendon retear. The dislodged rotator cuff anchor position could be determined on coronal and sagittal MRIs, providing the orthopedic surgeon a preoperative map for tendon reattachment and retrieval of the dislodged rotator cuff anchor. Four patients had loose rotator cuff anchors but intact supraspinatus tendons. Three patients had supraspinatus tendon retears, but the rotator cuff anchors were intact. In all 16 patients, arthroscopic findings confirmed MRI findings. Fourteen patients had intact rotator cuff anchors and intact supraspinatus tendons on MRI. Of these 14 patients, five had second-look arthroscopy confirming MRI findings. CONCLUSION: MRI is useful in the assessment of patients with persistent or new-onset pain after supraspinatus tendon repair with rotator cuff anchors. MRI provides a presurgical map for second-look arthroscopy to assess retear of the supraspinatus tendon and also aids in retrieval of dislodged rotator cuff anchors.     

Equivalent clinical results of arthroscopic single-row and double-row suture anchor repair for rotator cuff tears: a randomized controlled trial

BACKGROUND: Restoring the anatomical footprint may improve the healing and mechanical strength of repaired tendons. A double row of suture anchors increases the tendon-bone contact area, reconstituting a more anatomical configuration of the rotator cuff footprint. HYPOTHESIS: There is no difference in clinical and imaging outcome between single-row and double-row suture anchor technique repairs of rotator cuff tears. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: The authors recruited 60 patients. In 30 patients, rotator cuff repair was performed with a single-row suture anchor technique (group 1). In the other 30 patients, rotator cuff repair was performed with a double-row suture anchor technique (group 2). RESULTS: Eight patients (4 in the single-row anchor repair group and 4 in the double-row anchor repair group) did not return at the final follow-up. At the 2-year follow-up, no statistically significant differences were seen with respect to the University of California, Los Angeles score and range of motion values. At 2-year follow-up, postoperative magnetic resonance arthrography in group 1 showed intact tendons in 14 patients, partial-thickness defects in 10 patients, and full-thickness defects in 2 patients. In group 2, magnetic resonance arthrography showed an intact rotator cuff in 18 patients, partial-thickness defects in 7 patients, and full-thickness defects in 1 patient. CONCLUSION: Single- and double-row techniques provide comparable clinical outcome at 2 years. A double-row technique produces a mechanically superior construct compared with the single-row method in restoring the anatomical footprint of the rotator cuff, but these mechanical advantages do not translate into superior clinical performance.     

Arthroscopic hybrid double-row rotator cuff repair

A Beath pin is drilled on the greater tuberosity under arthroscopy using an anterior cruciate ligament guide. The suture anchor is inserted in the lateral aspect of the footprint. Sutures are then passed through the margins of the rotator cuff tear and tied with sliding knot. One strand of tied suture anchor is passed into the bony trough. One passed strand and the other strand are then tied with a non-sliding knot on the greater tuberosity. The strength of cuff fixation does not only rely on the quality of the bone, it restores the footprint contact area of rotator cuff, and reduces the use of suture anchors to the minimum in this method.     

Supplementation of rotator cuff repair with a bioresorbable scaffold

BACKGROUND: Repair of a torn rotator cuff should have sufficient initial strength of the fixation to permit appropriate rehabilitation. HYPOTHESIS: Augmentation with a woven polylactic acid scaffold strengthens repairs of the rotator cuff. STUDY DESIGN: Controlled laboratory study. METHODS: In the suture-anchor model, 10 pairs of sheep infraspinatus tendons were detached and repaired to suture anchors. In half of the matched specimens, the repair was reinforced with a woven poly-lactic acid scaffold repaired with the tendon to bone. In the bone-bridge model, sutures were passed through a trough and over a bone bridge distal to the greater tuberosity; half were reinforced by the scaffold. The repairs were tested to failure with a hydraulic testing machine. RESULTS: The mean ultimate strength of suture-anchor repairs augmented with the scaffold (167.3 +/- 53.9 N) was significantly greater than that of nonaugmented fixation (133.2 +/- 38.2 N). Failure occurred when the tendon pulled through the sutures; the scaffold remained intact. Scaffold reinforcement of the bone bridge significantly increased the ultimate strength from 374.6 +/- 117.6 N to 480.9 +/- 89.2 N, and the scaffold remained intact in 8 of 10 specimens. CONCLUSIONS: The scaffold significantly increased the initial strength of rotator cuff repair by approximately 25%.     

Effect of cyclic loading on new polyblend suture coupled with different anchors

BACKGROUND: Secure tendon-to-bone fixation is essential for successful rotator cuff repair. Biomechanical properties of devices used in rotator cuff repair should be better understood. PURPOSE: To evaluate the response to incremental cyclic loading of 6 different anchor-suture complexes commonly used in rotator cuff repair. STUDY DESIGN: Controlled laboratory study. METHODS: Two absorbable anchors 5 mm and 6.5 mm in diameter and 1 metallic anchor, coupled with Ethibond or FiberWire, were tested on 5 pairs of fresh-frozen human cadaveric shoulders. An incremental cyclic load was applied until failure using a Zwich-Roell Z010 electromechanical testing machine. The ultimate failure load and mode of failure were recorded. An analysis of variance model was used for statistical analysis. RESULTS: The FiberWire suture coupled with both absorbable and metallic anchors provided statistically significantly stronger fixation. However, although the metallic anchors in most cases failed because of slippage of the anchor, absorbable anchors failed because of rupture of the eyelet. CONCLUSIONS: The FiberWire seems to increase the strength of fixation devices under cyclic load using both absorbable and metallic anchors, with relevant differences in failure mode (slippage of the metallic anchor and eyelet failure in the absorbable anchor). CLINICAL RELEVANCE: Use of the FiberWire suture might change the mode of failure of the suture-anchor complexes.     

Pullout strength of suture anchors in comparison with transosseous sutures for rotator cuff repair

Suture anchors are increasingly gaining importance in rotator cuff surgery. This means they will be gradually replacing transosseous sutures. The purpose of this study was to compare the stability of transosseous sutures with different suture anchors with regard to their pullout strength depending on bone density. By means of bone densitometry (CT scans), two groups of human humeral head specimens were determined: a healthy and a osteopenic bone group. Following anchor systems were being tested: SPIRALOK™ 5.0 mm (resorbable, DePuy Mitek), Super Revo 5 mm (titanium, Linvatec), UltraSorb (resorbable, Linvatec) and the double U-sutures with Orthocord™ USP 2 (partly resorbable, DePuy Mitek) and Ethibond Excel 2 (non-resorbable, Ethicon). The suture anchors/double U-sutures were inserted in the greater tuberosity 12 times. An electromechanical testing machine was used for cyclic loading with power increasing in stages. We recorded the ultimate failure loads, the system displacements and the modes of failure. The suture anchors tended to bring about higher ultimate failure loads than the transosseous double U-sutures. This difference was significant in the comparison of the Ethibond suture and the SPIRALOK 5.0 mm—both in healthy and osteopenic bone. Both the suture materials and the SPIRALOK 5.0 mm showed a significant difference in pullout strength on either healthy or osteopenic bone; the titanium anchor SuperRevo 5 mm and the tilting anchor UltraSorb did not show any significant difference in healthy or osteopenic bone. There was no significant difference concerning system displacement (healthy and osteopenic bone) between the five anchor systems tested. The pullout strength of transosseous sutures is neither on healthy nor on osteopenic bone higher than that of suture anchors. Therefore, even osteopenic bone does not constitute a valid reason for the surgeon to perform open surgery by means of transosseous sutures. The choice of sutures in osteopenic bone is of little consequence anyway since it is mostly the bone itself which is the limiting factor.     

Rotator cuff repair. A biomechanical comparison of three techniques

BACKGROUND: The most common complication of rotator cuff repair is structural failure at the repair site. A single-layer repair does not adequately reproduce the anatomic insertion and may not optimize fixation strength. HYPOTHESIS: A double-layer rotator cuff repair will have greater initial fixation strength than a single-layer repair. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve fresh-frozen matched pairs of cadaveric shoulders were repaired by using dual-site fixation with both suture anchors and transosseous tunnels on one side (technique 1). Fixation was achieved by using suture anchors with horizontal mattress sutures and bone tunnels with modified Mason-Allen sutures. Half of the contralateral matched shoulders underwent fixation with suture anchors and simple sutures to simulate commonly used arthroscopic methods (technique 2) and, in the rest, fixation was achieved by using transosseous tunnels and modified Mason-Allen sutures (technique 3). Repaired specimens then underwent cyclic loading at physiologic rates and loads. The number of cycles to failure, which was defined as a 1-cm gap at the repair site, was then recorded. An arbitrary cut-off point of 5000 cycles was chosen. RESULTS: The mean number of cycles to failure with technique 1 (3694 +/- 1980 cycles) was significantly greater than that with either technique 2 (1414 +/- 1888 cycles) or technique 3 (528 +/- 683 cycles). Failure was predominantly through bone. CONCLUSIONS: The initial fixation strength of our double-layer repair exceeds that of isolated single-layer repairs with either suture anchors or transosseous tunnels.     

A new technique: in vitro suture anchor fixation has superior yield strength to bone tunnel fixation for distal biceps tendon repair

BACKGROUND: Suture anchor and bone tunnel fixations are used for distal biceps tendon repairs and have not been compared. HYPOTHESIS: Suture anchor fixation is equal or superior to bone tunnel fixation. STUDY DESIGN: Randomized controlled in vitro study. METHODS: A new fixation technique was compared to traditional bone tunnel fixation of distal biceps tendon ruptures between randomly selected sides of nine matched-pair, fresh-frozen elbow specimens from cadaveric donors (mean age = 74.7 years). Bone densities were determined. The distal biceps tendon was attached to the actuator of a servohydraulic load frame and loaded to tensile failure at a constant rate of 4 mm/sec. Bone density, sex, age, side, tuberosity area, repair, failure type, repair stiffness, and yield strength were compared. RESULTS: Superior yield strength of suture anchor fixation (263 N) compared to bone tunnel fixation (203 N) (P = 0.0233) were demonstrated. When suture anchor fixation failure (1 of 9) occurred, the matched pair also failed. CONCLUSION: Suture anchor fixation offers an equal if not superior alternative to bone tunnel fixation for repair of the distal biceps tendon in the specimens tested. Clinical Relevance: Suture anchor fixation may be used for distal biceps tendon repairs.     

Biomechanical evaluation of a new technique for rotator cuff repair

BACKGROUND: In recent studies, investigators have used a cyclic loading model to investigate the efficacy of rotator cuff fixation modalities. HYPOTHESIS: A bioabsorbable poly-D-lactic acid screw and toothed washer implant will provide more stable fixation of rotator cuff repairs than standard suture anchor techniques. STUDY DESIGN: Controlled laboratory study. METHODS: Forty bovine shoulders (ages 3 to 6 months) had 1 x 2 cm defects created in the infraspinatus tendon. There were five repair groups (eight specimens per group) consisting of either two screw and washer implants or two suture anchors. Four suture techniques were tested: single-loaded anchors with simple sutures, double-loaded anchors with simple sutures, single-loaded anchors with horizontal mattress sutures, or single-loaded anchors with modified Mason-Allen sutures. Repairs were loaded at 5-second cycles from 10 to 180 N with use of a hydraulic testing machine. The number of cycles to gap formation of 5 and 10 mm was recorded. RESULTS: Gap formation of 5 and 10 mm occurred significantly later for the screw repair group than for any of the suture anchor groups. There was no significant difference between suture groups. CONCLUSIONS: The bioabsorbable screw and washer provided more stable fixation than suture anchor techniques under isometric cyclic loading conditions. Clinical Relevance: This is a time-zero study of implant performance. The results indicate that the implant may decrease clinical failures in the early postoperative period under standard rehabilitation protocols.     

Trabecular microstructure and surface changes in the greater tuberosity in rotator cuff tears

OBJECTIVE: When planning surgery in patients with rotator cuff tear, strength of bone at the tendon insertion and trabecular bone structure in the greater tuberosity are usually taken into consideration. We investigated radiographic changes in bone structure of the greater tuberosity in rotator cuff tears. DESIGN: Twenty-two human cadaveric shoulders from subjects ranging from 55 to 75 years of age were obtained. The integrity of the rotator cuff was examined by sonography to determine if it is intact without any tear, or torn partially or completely. The humeral head was sectioned in 3 mm thick coronal slab sections and microradiographed. After digitization of the microradiographs and imaging processing with in-house semi-automated image processing software tools developed using software interfaces on a Sun workstation, the trabecular histomorphometrical structural parameters and connectivity in the greater tuberosity were quantified. The degenerative changes on the surface of the greater tuberosity were interpreted blindly by 2 independent readers. RESULTS: Among the 22 shoulder specimens, the rotator cuff was found intact in 10 shoulders, partially in 7 and fully torn in 5. Statistically significant loss in apparent trabecular bone volume fraction, number of trabecular nodes, and number of trabecular branches, and a statistically significant increase in apparent trabecular separation and number of trabecular free ends were found in the greater tuberosity of the shoulders with tears. The loss was greater in association with full tear than in partial tear. Thickening of the cortical margin of the enthesis, irregularity of its surface, and calcification beyond the tidemark were observed in 2 (20%) shoulders with intact rotator cuff, in 6 (86%) shoulders with partial tear, and in 5 (100%) shoulders with full tear. CONCLUSIONS: Rotator cuff tears are associated with degenerative changes on the bone surface and with disuse osteopenia of the greater tuberosity. Aging, degenerative enthesopathy of the supraspinatus tendon, and rotator cuff tears appear closely related.     

Biomechanical evaluation of rotator cuff fixation methods

Initial fixation strength and failure mode for various rotator cuff reattachment techniques (variations of the McLaughlin technique) were evaluated. Repair methods included standard suture (control), reinforced suture [expanded polytetrafluoroethylene (PTFE) patch and polydioxanone (PDS) tape augmentation] and stapling (nonarthroscopic and arthroscopic soft-tissue staples). The average strength of intact rotator cuff tissue (supraspinatus tendon) was also determined. The different rotator cuff repairs, including at least one control, were performed on fresh-frozen human cadaver shoulder pairs. Repairs were tested to failure in pure tension with the shoulder fixed in 60 degrees of abduction. Load and displacement data were normalized to controls, grouped according to failure modes, and statistically analyzed. The two basic failure modes observed were 1) bone failure, or suture tearing through the bone (indicating weak bone stock) and 2) tendon failure, or suture tearing of the rotator cuff. Gross comparisons between intact and repaired tendons indicated that the intact tendon was two to three times stronger than the repaired tendon. Based on the mode of failure and lack of increased strength after repair, the use of staples for cuff attachment is discouraged. PDS tape suture reinforcement did not increase fixation strength. In contrast, PTFE patch suture augmentation demonstrated statistically higher initial failure loads than did the control and was of specific benefit for shoulders with weak bone stock.     

MRI检查肩袖损伤的临床分析

目的分析肩袖损伤在MR检查时的不同扫描定位及在不同序列上的显示效果。方法对40例肩袖损伤患者行横断位T2WI,斜矢状位T1WI,斜冠状位脂肪抑制(STIR)及双斜冠状位T1WI、T2WI、脂肪抑制(STIR)扫描,分析斜冠状位与双斜冠状位图像对冈上肌、冈上肌肌腱以及肱骨干长轴的显示能力和对肩袖损伤的显示效果;以及在双斜冠状位各个序列(T1WI、T2WI、脂肪抑制STIR)中对肩袖损伤的图像显示效果按评价标准进行评价和对显示结果比较。结果 40例肩关节的斜冠状位和双斜冠状位都能全部显示冈上肌长轴,且双斜冠状位能把冈上肌、冈上肌肌腱全长及肱骨干长轴显示于一幅图像中,而斜冠状位不能;斜冠状位(STIR)显示肩袖部分撕裂和完全撕裂的分别为13例和14例,双斜冠状位(STIR)分别为22例和14例;双斜冠状位T1WI、T2WI、STIR三个序列显示肩袖结构好、较好、差的例数分别为(10、26、32;14、11、7;3、2、1)双斜冠状位T1WI、T2WI、STIR三个序列发现冈上肌肌腱、肩胛下肌肌腱、冈下肌肌腱、小圆肌肌腱、肱二头肌长头肌腱异常的例数分别为(4、21、28;2、9、15;1、6、10;0、2、4;0、1、2)。结论双斜冠状位对冈上肌、冈上肌肌腱全长及肱骨干长轴的显示能力和对肩袖损伤的显示结果均优于斜冠状位;双斜冠状位的脂肪抑制(STIR)序列对肩袖损伤的显示效果和结果均优于T2WI和T1WI。