Intact Tendon Research Articles

Targeting danger molecules in tendinopathy: the HMGB1/TLR4 axis

ObjectivesTo seek evidence of the danger molecule, high-mobility group protein B1 (HMGB1) expression in human tendinopathy and thereafter, to explore mechanisms where HMGB1 may regulate inflammatory mediators and matrix regulation...

Transosseous-equivalent repair with and without medial row suture tying: a cadaveric study of infraspinatus tendon strain measurement

BackgroundHow the use of the transosseous-equivalent (TOE) technique effects the stress concentration in repaired rotator cuff tendon is unknown. This study was conducted to determine the strain between the intact rotator cuff tendon and the tendon repaired using the TOE technique with and without medial row suture tying.Materials and methodsStrain of the infraspinatus tendon from 10 fresh-frozen cadavers was measured at the (A) tendon insertion, (B) tendon footprint, (C) tendon of the medial suture level, and (D) musculotendinous junction of the tendon. The strain was measured during 2 cycles of internal and external rotations while applying 4 different loads to the infraspinatus. After the intact tendon was evaluated, an artificially created tear of the infraspinatus was repaired using the TOE technique. Medial row sutures were tied in 5 shoulders (T group) and untied in the rest (UT group). The strains at 4 sites were compared between the intact and the TOE-repaired tendon and between the T and UT groups.ResultsThe strain was significantly reduced at site B in the repaired tendon in the T and UT groups compared with the intact tendon for all loads (P < .05). At site C, the strain increased for all loads in the T group compared with the intact tendon (P < .05).ConclusionThe strain of the tendon over the footprint area was significantly smaller than the intact tendon when repaired with the TOE technique. The strain at the medial suture level was significantly greater when the medial sutures were tied compared with those untied.

The lateral malleolar bony fleck classified by size and pathoanatomy: The IOFAS classification

BackgroundThis study analyzes position of the peroneal tendons and status of the superior peroneal retinaculum (SPR) whenever a lateral malleolar bony flake fracture occurs. MethodsTwenty-four patients had a lateral malleolar bony fleck on anteroposterior ankle radiographs, either in isolation or associated with other hindfoot injuries. We studied size of the bony flecks, presence or absence of peroneal tendon dislocation and pathoanatomy on CT scans. ResultsIn 11 patients, a small bony fleck lies within the superior peroneal retinaculum and contiguous periosteum, which are stripped off the lateral fibula (Class II lesions). Tendons dislocate into the subperiosteal pouch thus formed, resembling Class I lesions without associated bony avulsion. Treatment for Class II is same as for Class I injuries. In 8 patients with a big bony fleck, tendons dislocate into the fracture site and SPR is intact (Class III lesions). In Class IV lesions, observed in 5 patients with 2-part calcaneal fracture/dislocation, SPR remains intact and peroneal tendons are not dislocated. The invariably large fleck results from the displacing lateral calcaneal fragment abutting against the fibula, whereas the dislocating tendons cause the bony avulsions in Classes II and III. ConclusionsDue to pathoanatomical differences, surgical approach and natural history of neglected lesions differ depending on size of the bony fleck. The SPR must not be incised in case of big Class III flecks.

Longitudinal Long-term Magnetic Resonance Imaging and Clinical Follow-up After Single-Row Arthroscopic Rotator Cuff Repair: Clinical Superiority of Structural Tendon Integrity

Background: The number of arthroscopic rotator cuff surgeries is consistently increasing. Although generally considered successful, the reported number of retears after rotator cuff repair is substantial. Short-term clinical outcomes are reported to be rarely impaired by tendon retears, whereas to our knowledge, there is no study documenting long-term clinical outcomes and tendon integrity after arthroscopic rotator cuff repair. Purpose: To investigate longitudinal long-term repair integrity and clinical outcomes after arthroscopic rotator cuff reconstruction. Study Design: Case series; Level of evidence, 4. Methods: Thirty patients who underwent arthroscopic rotator cuff repair with suture anchors for a full-tendon full-thickness tear of the supraspinatus or a partial-tendon full-thickness tear of the infraspinatus were included. Two and 10 years after initial arthroscopic surgery, tendon integrity was analyzed using magnetic resonance imaging (MRI). The University of California, Los Angeles (UCLA) score and Constant score as well as subjective questions regarding satisfaction with the procedure and return to normal activity were used to evaluate short- and long-term outcomes. Results: At the early MRI follow-up, 42% of patients showed a full-thickness rerupture, while 25% had a partial rerupture, and 33% of tendons remained intact. The 10-year MRI follow-up (129 ± 11 months) showed 50% with a total rerupture, while the other half of the tendons were partially reruptured (25%) or intact (25%). The UCLA and Constant scores significantly improved from preoperatively (UCLA total: 50.6% ± 20.2%; Constant total: 44.7 ± 10.5 points) to 2 years (UCLA total: 91.4% ± 16.0% [P < .001]; Constant total: 87.8 ± 15.3 points [P < .001]) and remained significantly higher after 10 years (UCLA total: 89.7% ± 15.9% [P < .001]; Constant total: 77.5 ± 15.6 points [P < .001]). The Constant total score and Constant strength subscore, but not the UCLA score, were also significantly better at 10 years postoperatively in patients with intact tendons compared with patients with retorn tendons (Constant total: 89.0 ± 7.8 points vs 75.7 ± 14.1 points, respectively [P = .034]; Constant strength: 18.0 ± 4.9 points vs 9.2 ± 5.2 points, respectively [P = .006]). The majority of patients rated their satisfaction with the procedure as “excellent” (83.3%), and 87.5% returned to their normal daily activities. Conclusion: Arthroscopic rotator cuff repair showed good clinical long-term results despite a high rate of retears. Nonetheless, intact tendons provided significantly superior clinical long-term outcomes, making the improvement of tendon healing and repair integrity important goals of future research efforts.

Arthroscopic Partial Repair of Irreparable, Massive Rotator Cuff Tears

Several treatment options for chronic, massive rotator cuff tears exist, and they include debridement with possible biceps tenotomy or tenodesis, open or arthroscopic partial repair, muscle or tendon transfer, superior capsule reconstruction, synthetic patch augmentation, and reverse total shoulder arthroplasty. The aim of this technique article is to describe our preferred surgical option for irreparable, massive rotator cuff tears with an irreparable supraspinatus, a reparable infraspinatus, and an intact or reparable subscapularis tendon.

Validity of ultrasound in diagnosis of tendon injuries in penetrating extremity trauma

BackgroundTendon ruptures are common musculoskeletal injuries all around the world. Correct and timely diagnosis of tendon injuries is obviously important for improving the treatment and minimizing the community costs. Ultrasound is now being considered as one of useful modalities in this area. ObjectiveThe preset study is going to validate the diagnostic ability of ultrasound in tendon injuries induced by penetrating extremity trauma. MethodsIn this prospective, observational study, patients with penetrating extremity trauma and suspicion of tendon injuries were enrolled in our study. A team of emergency medicine (EM) residents performed ultrasound examination in these cases after attending the specific workshop and acquiring necessary skills in normal and abnormal tendon ultrasound examination. Then another team of either EM or orthopedic residents explored patients' wounds and determined intact or injured tendons under direct visual observation. The results were analyzed to validate sensitivity and specificity of ultrasound as an alternative diagnostic test. ResultsSeventy-one patients were enrolled in our study and 11 patients were excluded during one year in 2014. Sixty patients, 11 with lower extremity and 49 with upper limb injuries were evaluated, among them 32 patients had extensor zone and 28 patients had flexure zone injuries. The overall sensitivity and specificity were calculated 94.4% (95% CI 72.7–99.8%) and 100% (95% 91.5–100.0%) respectively. ConclusionsOur results were similar to previous findings. Ultrasound can effectively differentiate injured from intact tendons in penetrating extremity trauma.

Compromised Neurotrophic and Angiogenic Regenerative Capability during Tendon Healing in a Rat Model of Type-II Diabetes.

Metabolic diseases such as diabetes mellitus type-II (DM-II) may increase the risk of suffering painful connective tissue disorders and tendon ruptures. The pathomechanisms, however, by which diabetes adversely affects connective tissue matrix metabolism and regeneration, still need better definition. Our aim was to study the effect of DM-II on expressional changes of neuro- and angiotrophic mediators and receptors in intact and healing Achilles tendon. The right Achilles tendon was transected in 5 male DM-II Goto-Kakizaki (GK) and 4 age-matched Wistar control rats. The left Achilles tendons were left intact. At week 2 post-injury, NGF, BDNF, TSP, and receptors TrkA, TrkB and Nk1 gene expression was studied by quantitative RT-PCR (qRT-PCR) and their protein distribution by immunohistochemistry in intact and injured tendons. The expression of tendon-related markers, Scleraxis (SCX) and Tenomodulin (TNMD), was evaluated by qRT-PCR in intact and injured tendons. Injured tendons of diabetic GK rats exhibited significantly down-regulated Ngf and Tsp1 mRNA and corresponding protein levels, and down-regulated Trka gene expression compared to injured Wistar controls. Intact tendons of DM-II GK rats displayed reduced mRNA levels for Ngf, Tsp1 and Trkb compared to corresponding intact non-diabetic tendons. Up-regulated Scx and Tnmd gene expression was observed in injured tendons of normal and diabetic GK rats compared to intact Wistar controls. However, these molecules were not up-regulated in injured DM-II GK rats compared to their corresponding controls. Our results suggest that DM-II has detrimental effects on neuro- and angiotrophic pathways, and such effects may reflect the compromised repair seen in diabetic Achilles tendon. Thus, novel approaches for regeneration of injured, including tendinopathic, and surgically repaired diabetic tendons may include therapeutic molecular modulation of neurotrophic pathways such as NGF and its receptors.

Acromion Index in Korean Population and Its Relationship with Rotator Cuff Tears.

BackgroundAmong the many causes of rotator cuff tears, scapular morphology is associated with the accelerating degenerative process of the rotator cuff. Acromion index (AI) was previously introduced and compared in two populations.MethodsWe enrolled 100 Korean patients diagnosed with full-thickness rotator cuff tears by magnetic resonance imaging and intraoperative arthroscopic findings between January and December 2013. Another 100 Korean patients with an intact rotator cuff tendon identified on magnetic resonance imaging and other shoulder diseases, such as frozen shoulder and instability, were enrolled as controls. We retrospectively compared these 100 rotator cuff tear patients (mean age, 63 years) and 100 controls (mean age, 51 years) in this study. Two independent orthopedic surgeons assessed the AI on radiographs. We performed an interobserver reliability test of the AI assessment, and then compared the AI between two groups.ResultsThe measurement of the AI showed excellent reliability (intraclass correlation coefficient, 0.82). The mean AI in the rotator cuff tear group was 0.68 and it was significantly different between groups (p<0.001, 95% confidence interval). The AI was not related to tear size.ConclusionsOur study showed that the AI was an effective predictive factor for rotator cuff tears in a Korean population.

Effects of Training Load and Leg Dominance on Achilles and Patellar Tendon Structure.

Detrimental changes in tendon structure increase the risk of tendinopathies. The aim of this study was to investigate the influence of individual internal and external training loads and leg dominance on changes in the Achilles and patellar tendon structure. The internal structure of the Achilles and patellar tendons of both limbs of 26 elite Australian footballers was assessed using ultrasound tissue characterization at the beginning and the end of an 18-wk preseason. Linear-regression analysis was used to estimate the effects of training load on changes in the proportion of aligned and intact tendon bundles for each side. Standardization and magnitude-based inferences were used to interpret the findings. Possibly to very likely small increases in the proportion of aligned and intact tendon bundles occurred in the dominant Achilles (initial value 81.1%; change, ±90% confidence limits 1.6%, ±1.0%), nondominant Achilles (80.8%; 0.9%, ±1.0%), dominant patellar (75.8%; 1.5%, ±1.5%), and nondominant patellar (76.8%; 2.7%, ±1.4%) tendons. Measures of training load had inconsistent effects on changes in tendon structure; eg, there were possibly to likely small positive effects on the structure of the nondominant Achilles tendon, likely small negative effects on the dominant Achilles tendon, and predominantly no clear effects on the patellar tendons. The small and inconsistent effects of training load are indicative of the role of recovery between tendon-overloading (training) sessions and the multivariate nature of the tendon response to load, with leg dominance a possible influencing factor.

Lymphatic Contribution to the Cellular Niche in Heterotopic Ossification

The objective of this study was to determine the contribution of lymphatic tissue to heterotopic ossification (HO). HO is the pathologic development of ectopic bone within soft tissues often following severe trauma. Characterization of the tissue niche supporting HO is critical to identifying therapies directed against this condition. Lymphangiogenesis is upregulated during incidents of trauma, thereby coincident with the niche supportive of HO. We hypothesized that lymphatic tissues play a critical role in HO formation. Mice underwent hindlimb Achilles' tendon transection and dorsal burn injury (burn/tenotomy) to induce HO. The popliteal and inguinal lymph nodes were excised ipsilateral to the tenotomy site. Flow cytometry and immunostaining were used to quantify and localize lymphoendothelium. MicroCT was used to quantify HO. Enrichment of mature lymphatic tissues was noted 2 weeks after injury at the tendon transection sites when compared with the contralateral, intact tendon based on LYVE1+ tubules (10.9% vs 0.8%, P < 0.05). Excision of the inguinal and popliteal nodes with draining popliteal lymphatic vessel significantly decreased the presence of mature lymphoendothelium 2 weeks after injury (10.9% vs 3.3%, P < 0.05). Bone-cartilage-stromal progenitor cells (CD105+/AlphaV+/Tie2-/CD45-/CD90-/BP1-) were also significantly decreased after lymph node excision (10.2% vs 0.5%, P < 0.05). A significant decrease was noted in the volume of de novo HO present within the soft tissues (0.12 mm vs 0.02 mm). These findings suggest that lymphatic vessels are intimately linked with the de novo formation bone within soft tissues following trauma, and their presence may facilitate bone formation.

Paper #27 - Correlation of clinical outcomes of retear and tear progression after arthroscopic rotator cuff repair

Background: Rotator cuff retear rate after arthroscopic cuff repair is still high despite advanced arthroscopic techniques and instrument evolution. Even if a retear occurs after rotator cuff repair, improvement in shoulder function is generally maintained, and it is known that rotator cuff integrity does not correlate with clinical outcomes. However, recent studies reported that clinical results of patients with a cuff retear are worse than those with a healed cuff. Therefore, functional outcomes of patients with rotator cuff retear are still on debate. This study evaluated factors related to clinical outcomes of rotator cuff retear after arthroscopic rotator cuff repair focusing on the importance of preoperative and postoperative changes of tear size. Materials and Methods: Four hundred and forty-two patients with full-thickness rotator cuff tear who underwent arthroscopic rotator cuff repair were included in this study. Patients who were possible to cover footprint completely, able to follow up over 2 years, and conducted postoperative MRI at 6 months for tendon integrity were included. The size of tear was measured on the oblique coronal and sagittal images of both preoperative and postoperative MRI. Intact tendon was defined as sufficient thickness of the repaired tendon showing continuity and a homogeneous low-intensity signal in the substance of cuff. Retear was defined as the repaired tendon showing complete discontinuity from footprint. Pain was measured by using VAS score, range of motion was recorded and functional outcomes were measured with ASES and Constant scores. Clinical outcomes were compared between patients with retears and intact cuff. Factors may affect clinical outcome such as preoperative tear size, changes of tear size and retear patterns were evaluated. Results: There were 233 males and 209 females with a mean age of 55 years (range; 46-75 years). Average follow-up period was 33 months (range 24-43 months). Fifty-eight patients (13.1%) had a retear confirmed by postoperative MRI. Patients with a healed cuff showed better shoulder functions than the patients with a retorn cuff (ASES; healed patients, 92.6 ± 9.5 and retear patients, 87.6 ± 12.4, P = .008). 1). Effect of preoperative rotator cuff tear size: In the patients with a preoperative large to massive size, patients with retear showed significant difference in functional outcomes (ASES: 86.5 ± 12.4 and Constant score: 88.7 ± 8.0) when compared with patients with a healed rotator cuff (ASES: 76.9 ± 9.7, P = .02 and 76.9 ± 11.7, P = .001). However, in patients with preoperative small and medium-sized tears, clinical outcomes were not significantly different irrespective of the status of healing of the cuff (ASES: healed cuff, 93.9 ± 7.8 and cuff retear, 93.8 ± 9.2 (P = .37), Constant score: healed cuff, 90.0 ± 11.7 and cuff retear, 91.5 ± 8.5 (P = .47)). 2). Comparative size of retear: Patients with smaller size of retear than the preoperative tear size (n = 28) showed significantly better functional outcomes and muscle strength recovery (Constant score: 90.5 ± 8.8) than those with equal or larger size of retear after surgery (n = 30) (Constant score: 83.7 ± 11.7, P = .025). 3). Retear pattern: Postoperative tear either at the footprint or at the musculotendinous junction did not influence the functional outcomes. 4). Risk factors for retear: Fatty degeneration more than grade 3 (odds ratio = 2.74, (CI: 1.19-6.36), P = .018) and preoperative large to massive rotator cuff tears (odds ratio = 2.2 (CI: 1.17-4.15), P = .015) were preoperatively affecting factors which were significant related to retear after surgery. Age at surgery, sex, symptom duration, arm dominance and associated pathology had no significant effect on the outcome of surgery. Conclusion: Preoperative large to massive rotator cuff tears, and fatty degeneration more than grade 3 are important contributing factors for retear after arthroscopic rotator cuff repair. Patients with preoperative small to medium sized tears had satisfactory clinical outcomes regardless of postoperative tendon integrity. However, in patients with a preoperative large to massive tear who develop retear, the functional outcomes are poorer than patients with a healed cuff. The patients with an equal or larger retorn tendon than preoperative size showed poorer Constant score and muscle strength regardless of preoperative sizes of tear. Therefore, surgeons should take more efforts and employ techniques to reduce the size of retear even if retear occurs.

Stochastic Response of Intact and a Removed Tendon Tension Leg Platform to Random Wave and Current Forces

This work analysed the dynamic response of intact and a removed tendon tension leg platform (TLP) in simultaneous action of random wave and current loads in normal and less severe environments. Two different sea states of extreme severe sea state but less probable and less severe state and most probable are considered in this study. The artificial random wave is simulated by Monte Carlo simulation using Pierson–Moskowitz spectrum. Wave diffraction effect is not considered since the ratio of characteristic dimension to wavelength is less than limit. The coupling in all degree of freedoms and various degrees of nonlinear effects is considered. The inertia, mass, damping matrices of equation of motion and hydrodynamic force vector are formulated and solved numerically using Newmark integration scheme. The statistical results show that removal of one tendon increases surge and tendon tension values, while heave and pitch are not adversely affected in both environments. The response values of the TLP in extreme severe sea state are quite higher compared to less severe sea state. The percentage increase in all degree of freedoms and tendon tension is <5 % when one tendon is removed as compared to intact tendon TLP. It could be concluded that maximum and minimum tension in tendon constraints is equally passed by the TLP tendons.

What Factors are Associated With Clinically Important Improvement After Shoulder Hemiarthroplasty for Cuff Tear Arthropathy?

In selected patients with a desire to maintain activity levels greater than those recommended after reverse total shoulder arthroplasty, hemiarthroplasty remains an option for treatment of cuff tear arthropathy (CTA). However, given the relatively small case series that have been reported to date, little is known regarding which patients will show functional improvement after this surgery. We asked: What factors are associated with achieving the minimum clinically important difference in the simple shoulder test (SST) after hemiarthroplasty for cuff tear arthropathy? Between 1991 and 2007, two surgeons at one academic center performed 48 shoulder hemiarthroplasties for CTA. No patients were known to have died before data collection, and of those not known to have died, 42 (88%) were available for followup at a mean of 48months (range, 24-132months). During that time, the general indications for this approach were glenohumeral arthritis with superior decentering of the humeral head. The majority of the patients with CTA were treated nonoperatively with patient-directed physical therapy and other modalities. A total of 42 patients (42 shoulders; 24 males and 18 females) with CTA were treated with hemiarthroplasty and followed for a mean of 48months (range, 24-132months). This is a retrospective study that made use of a longitudinally maintained database, which included physical examination of ROM, the SST, VAS, and standardized radiographs. At latest followup, 33 of 42 patients achieved a clinically important percentage of maximum possible improvement (%MPI) in SST score, defined as an improvement of 30% of the total possible improvement on the 12-point scale (with higher scores representing better results). Intraoperative findings of a rotator cuff tear limited to the supraspinatus and infraspinatus (odds ratio [OR], ∞; 95% CI, 2.01 to ∞; p=0.020) and limited preoperative external rotation (15° [range, -40° to 45°] vs 35° [range, 20°-45°], OR, 0.71; 95% CI, 0.38-0.90; p<0.001) were associated with achieving the defined minimum functional improvement (30% of MPI) on multivariate analysis. Preoperative active elevation (p=0.679) and use of a CTA-specific implant (p=0.707) were not significantly associated with achievement of 30% of MPI. Patients with intact teres minor and subscapularis tendons and patients with lower preoperative external rotation had a better prognosis for achieving a clinically important percentage of MPI at short-term followup. Although some patients were followed for more than 10years, the majority were followed for fewer than 5years; future studies will need to determine whether these early functional results are maintained for longer periods. Level III, therapeutic study.

Preservation of bursal-sided tendon in partial-thickness articular-sided rotator cuff tears: a novel arthroscopic transtendon anatomic repair technique.

The purpose of this study was to introduce a novel arthroscopic transtendon anatomic repair technique that spares the intact bursal-sided tendon in articular-sided partial-thickness rotator cuff tears (PTRCT) and to present shoulder functional outcomes in patients with symptomatic articular-sided PCRCT that involves more than 50% of its thickness after arthroscopic repair using a novel technique. Eighteen patients with symptomatic articular-sided PCRCT involving more than 50% of the tendon's thickness underwent arthroscopic repair using a devised technique. The devised technique restores only the torn articular portion of the rotator cuff at the anatomical footprint using a suture anchor, and preserves the integrity of the corresponding bursal-sided tendon by tying knots at the most lateral bursal side on the subacromial space. Clinical and functional outcome using ASES and Constant scores were evaluated. The structural integrity of the rotator cuff was evaluated by MRI at 6months postoperatively. Pain relief and shoulder functional outcomes were encouraging during the recovery phase after operation. ASES (preoperative 54.0±10.3 to postoperative 92.6±8.0), Constant score (61.2±8.5-88.0±5.3), VAS for pain (4.9±2.6-0.6±0.7) improved significantly after arthroscopic transtendon anatomic repair (p<0.001). No patients had rotator cuff retears on 6-month MRI. No complications related to surgical procedures had occurred. The devised technique of arthroscopic transtendon repair provided satisfactory functional outcomes without postoperative discomforts. This technique minimizes over-tightening of the articular layer and reduces tension mismatches between the articular and bursal layers, which are considered as important factors for improvement of postoperative shoulder motion.

The Effect of Suture Caliber and Number of Core Strands on Repair of Acute Achilles Ruptures

Category: Sports Introduction/Purpose: Controversy exists in Achilles rupture management with options ranging from nonoperative care to open surgical repair. Current literature suggests re-rupture rates are lower with operative repair; therefore, surgery is recommended for active populations. The effect of suture caliber or number of core stands has not been studied in Achilles repair. Varying these factors may allow for a construct capable of earlier weight-bearing and rehabilitation. We hypothesized the number of core strands and suture caliber used in Achilles repair would significantly affect strength and gapping during a simulated early rehabilitation protocol. Methods: Sixteen cadaveric human foot and ankle specimens with no prior injuries or surgeries were utilized. Simulated midsubstance Achilles ruptures were created 6 cm proximal to the calcaneal insertion in 13 ankles. Specimens were randomly allocated to 1 of 4 groups: (1) intact Achilles tendon, (2) open repair using No. 2 suture with four core sutures and two 2mm suture-tape core sutures, (3) open repair using No. 2 suture with two core sutures and four 2mm suture-tape core sutures, and (4) open repair using No. 2-0 suture with 12 core sutures. Repairs consisted of three modified Kessler sutures and an epitenon stitch with a 3-0 monofilament suture. Specimens were subjected to a cyclic loading protocol simulating early, progressive postoperative rehabilitation: 250 cycles at 1 Hz for each loading range: 20-100, 20-200, 20-300, and 20-400 N. A 1-way ANOVA was used to test significance among repair groups. Results: During biomechanical testing, all repairs survived the first two loading stages. However, elongation trends during stage 1 (Figure 1) were consistent among subsequent cyclic loading stages. No significant elongation differences were observed between any of the repair groups (Groups 2-4), with mean displacements of 4.94 ± 0.90 mm, 3.93 ± 0.92 mm, and 5.35 ± 0.34 mm, respectively, at the end of the first loading stage. In Group 2, one repair failed during the fourth stage and 4 survived all four stages. In Group 3, one repair failed during the third stage and two repairs during the fourth stage. In Group 4, two repairs failed during the fourth stage and two survived all four stages. The average number of cycles to failure for Groups 2-4 was 967, 783, and 940 cycles, respectively. Conclusion: In this study, all but one repair survived 750 cycles. This was superior to a 6 core strand repair with No. 2 suture similarly evaluated in a previous study (427 cycles). When 4 of 6 strands were substituted with suture-tape, repair gapping decreased initially; yet, these repairs failed earlier. Gapping in Groups 2 and 4 was similar to the previously evaluated repair; however, the number of cycles to failure was higher. Therefore, substituting suture-tape for 2 core strands or doubling the core strands with a smaller caliber suture may be biomechanically superior and allow for earlier return to function.

An in vitro scratch tendon tissue injury model: effects of high frequency low magnitude loading

ABSTRACTThe healing process of ruptured tendons is suboptimal, taking months to achieve tissue with inferior properties to healthy tendon. Mechanical loading has been shown to positively influence tendon healing. However, high frequency low magnitude (HFLM) loads, which have shown promise in maintaining healthy tendon properties, have not been studied with in vitro injury models. Here, we present and validate an in vitro scratch tendon tissue injury model to investigate effects of HFLM loading on the properties of injured rat tail tendon fascicles (RTTFs). A longitudinal tendon tear was simulated using a needle aseptically to scratch a defined length along individual RTTFs. Tissue viability, biomechanical, and biochemical parameters were investigated before and 7 days after culture . The effects of static, HFLM (20 Hz), and low frequency (1 Hz) cyclic loading or no load were also investigated. Tendon viability was confirmed in damaged RTTFs after 7 days of culture, and the effects of a 0.77 ± 0.06 cm scratch on the mechanical property (tangent modulus) and tissue metabolism in damaged tendons were consistent, showing significant damage severity compared with intact tendons. Damaged tendon fascicles receiving HFLM (20 Hz) loads displayed significantly higher mean tangent modulus than unloaded damaged tendons (212.7 ± 14.94 v 92.7 ± 15.59 MPa), and damaged tendons receiving static loading (117.9 ± 10.65 MPa). HFLM stimulation maintained metabolic activity in 7-day cultured damaged tendons at similar levels to fresh tendons immediately following damage. Only damaged tendons receiving HFLM loads showed significantly higher metabolism than unloaded damaged tendons (relative fluorescence units —7021 ± 635.9 v 3745.1 ± 641.7). These validation data support the use of the custom-made in vitro injury model for investigating the potential of HFLM loading interventions in treating damaged tendons.

Nonlinear dynamic response of tension leg platform under environmental loads

This paper investigated the platform motion and tether tension of tension leg platform subjected to eight sea states ranging from extreme to moderate states. The mass, stiffness and damping force matrices were formulated for the platform and the tethers were considered as non-linear springs. The surface elevation and wave kinematics were calculated by small wave amplitude theory. On the other hand, the force vector was calculated by integrating over the entire length of the hull members using Morison equation. The various degree of non-linearity considered include the drag force, the variable added mass, large displacement as well as variations in tether tension. A finite element numerical research program was developed for solution of the nonlinear problem. The statistical response parameters for the degrees of freedom show that as we move towards the less severe sea states, all the responses were decreasing. Response comparison of one tether missing and an intact tendon of tension leg platform show an increase in surge and tether tension but heave response decreased due to reduction in stiffness against vertical movement. Dynamic analysis of the platform under the combined action of wave, current and wind is recommended so as to know true platform behaviours.

Morphometrics of the Anterior Belly and Intermediate Tendon of the Digastric Muscle: Sexual Dimorphism and Implications for Surgery.

The anterior belly of the digastric muscle (ABDM) is important in a variety of surgeries including submental lipectomy, rhytidectomy, alteration of the cervicomental angle via muscle resection, the "digastric corset" procedure for submental rejuvenation, the submental artery flap, and reanimation of the mouth after facial nerve palsy. Despite its clinical significance, little information exists regarding the morphometrics of the ABDM or its associated intermediate tendon. This study analyzed a total of 35 intact ABDMs and 43 intact intermediate tendons from 23 cadavers. Measurements were taken of the following parameters: muscle belly area, muscle belly length, intermediate tendon length, and intermediate tendon width at mid-tendon. Normative descriptive statistics are included within the report. Males were found to have significantly longer left-sided muscle bellies than right-sided bellies from males (U = 23.0; P = 0.044), left-sided bellies from females (U = 19.0; P = 0.020), and right-sided bellies from females (U = 12.0; P = 0.035). The morphometry, including sexual dimorphism, presented in this report can aid in the surgical planning and execution of numerous operations performed in head and neck, especially digastric muscle transfer surgery.

Anatomy and relations of the infraspinatus and the teres minor muscles: a fresh cadaver dissection study.

Despite their functional importance, the infraspinatus (ISP) and teres minor (TM) muscles have been little investigated. This study aimed to describe the macroscopic morphology, innervation, and inter-relations of the ISP and TM muscles. Forty fresh cadaver dissections and histologic analysis were performed. Three groups of specimens were distinguished according to the rotator cuff tendon status: (1) intact rotator cuff; (2) supraspinatus tendon tears with intact ISP tendon; and (3) both supraspinatus and ISP tendons torn. Muscle fiber organization and muscle and tendon length were recorded. ISP and TM innervation and fiber structure were studied. ISP muscles were composed of three groups of fiber organized in two planes: two superficial groups, with mean pennation angles of, respectively, 27°±4° and 23°±3° with respect to the axis of the central tendon of the underlying group. TMs were thick fusiform muscles showing a parallel organization; 26 specimens (67%) had aponeuroses isolating the TM, with a mean length of 5.2±2.7cm. Rotator cuff lesions were associated with relatively greater ISP tendon than muscle length. Innervation of the ISP muscle comprised 2-4 main branches from the suprascapular nerve and that of the TM 1 branch from the axillary nerve. ISP muscle body morphology derives from three groups of fibers in two planes. The TM has a parallel organization. Several nerve branches innervate the ISP muscle, whereas only one supplies the TM. The limits between the two muscles bodies consist of an aponeurotic fascia in two-thirds of cases.

IL-17A mediates inflammatory and tissue remodelling events in early human tendinopathy.

Increasingly, inflammatory mediators are considered crucial to the onset and perpetuation of tendinopathy. We sought evidence of interleukin 17A (IL-17A) expression in early human tendinopathy and thereafter, explored mechanisms whereby IL-17A mediated inflammation and tissue remodeling in human tenocytes. Torn supraspinatus tendon (established pathology) and matched intact subscapularis tendon (representing ‘early pathology’) along with control biopsies were collected from patients undergoing shoulder surgery. Markers of inflammation and IL-17A were quantified by RT-PCR and immunohistochemistry. Human tendon cells were derived from hamstring tendon obtained during ACL reconstruction. In vitro effects of IL-17A upon tenocytes were measured using RT-PCR, multiplex cytokine assays, apoptotic proteomic profiling, immunohistochemistry and annexin V FACS staining. Increased expression of IL-17A was detected in ‘early tendinopathy’ compared to both matched samples and non-matched control samples (p < 0.01) by RT-PCR and immunostaining. Double immunofluoresence staining revealed IL-17A expression in leukocyte subsets including mast cells, macrophages and T cells. IL-17A treated tenocytes exhibited increased production of proinflammatory cytokines (p < 0.001), altered matrix regulation (p < 0.01) with increased Collagen type III and increased expression of several apoptosis related factors. We propose IL-17A as an inflammatory mediator within the early tendinopathy processes thus providing novel therapeutic approaches in the management of tendon disorders.