An Analysis of Extensor Carpi Ulnaris Groove Morphology and Tendon Instability

BACKGROUND

The extensor carpi ulnaris (ECU) tendon has a distinct subsheath at the distal ulna. Symptomatic tears of this subsheath and subluxation of the ECU tendon often require reconstruction. We sought to determine the anatomical constraints of the ECU subsheath.

METHODS

The ECU subsheath was exposed on 12 fresh-frozen upper extremities. The tip of the ulnar styloid, the distal ulnar joint surface, and the proximal extent of the distal radio-ulnar joint were identified and dimensions measured. Subluxation of the tendon was then assessed with and without an intact subsheath in 9 specimens. The travel of the tendon was measured in pronation through supination and flexion before and after sectioning of the subsheath.

RESULTS

The ECU subsheath is 8.9 mm (standard deviation [SD] = 0.8 mm) wide proximally and 9.0 mm (SD = 1.2 mm) distally. The distal ulnar insertion is 0.5 mm (SD = 0.8 mm) proximal to the tip of the styloid, and stretches 10.2 mm (SD = 2.7 mm) proximally. From maximum pronation to maximum supination and flexion, the ECU tendon traveled 3.32 mm (SD = 4.24) medially when the subsheath was intact and 5.42 mm (SD = 5.0 mm) after sectioning. The maximum depth of the ulnar groove was 2.5 mm (1.59-3.56 mm). There was no significant association between changes in ECU subluxation and the depth of the ECU groove (Spearman's rho = 0.25).

CONCLUSION

The ECU subsheath is roughly 1 cm square stretching proximally from the ulnar styloid. ECU groove depth is not a significant independent predictor of tendon subluxation.

Tendon Healing in a Mouse Model of Loeys-Dietz Syndrome: Controlled Study Using a Patellar Tendon Transection Model

BACKGROUND

Loeys-Dietz syndrome (LDS) is a rare autosomal-dominant connective tissue disorder caused by genetic mutations in the transforming growth factor-β (TGFβ) signaling pathway. In addition to vascular malformations, patients with LDS commonly present with bone and tendon abnormalities, including joint laxity. While TGFβ signaling dysregulation has been implicated in many of these clinical manifestations, the degree to which it influences the tendinopathy and tendon healing issues in LDS has not been determined.

METHODS

Wound healing after patellar tendon transection was compared between wild-type (WT) and Tgfbr2-mutant (LDS) mice (7 mice per group). In all mice, the right patellar tendon was transected at midsubstance, while the left was untouched to serve as a control. Mice were euthanized 6 weeks after surgery. Tendon specimens were harvested for histopathologic grading according to a previously validated scoring metric, and gene expression levels of Mmp2, Tgfb2, and other TGFβ-signaling genes were assayed. Between-group comparisons were made using 1-way analysis of variance with post hoc Tukey honestly significant difference testing.

RESULTS

Expression levels of assayed genes were similar between LDS and WT tendons at baseline; however, at 6 weeks after patellar tendon transection, LDS tendons showed sustained elevations in Mmp2 and Tgfb2 compared with baseline values; these elevations were not seen in normal tendons undergoing the same treatments. Histologically, untreated LDS tendons had significantly greater cellularity and cell rounding compared with untreated WT tendons, and both WT and LDS tendons had significantly worse histologic scores after surgery.

CONCLUSION

We present the first mechanistic insight into the effect of LDS on tendons and tendon healing. The morphologic differences between LDS and WT tendons at baseline may help explain the increased risk of tendon/ligament dysfunction in patients with LDS, and the differential healing response to injury in LDS may account for the delayed healing and weaker repair tissue.

LEVEL OF EVIDENCE

Level V.

Absent pyramidal eminence and stapedial tendon associated with congenital stapes footplate fixation: Intraoperative and radiographic findings

OBJECTIVE

Report an association between congenital stapes footplate fixation (CSFF) and radiological absence of the pyramidal eminence and stapedial tendon.

PATIENTS

Children and adults with intraoperatively confirmed CSFF and an absent stapedial tendon.

INTERVENTIONS

Computed tomography (CT); exploratory tympanotomy with stapedotomy.

MAIN OUTCOME MEASURES

Absence of a pyramidal eminence and stapedial tendon aperture identified on preoperative CT that was confirmed intraoperatively.

RESULTS

Eight patients with intraoperative confirmation of CSFF and absent stapedial tendon were retrospectively identified. The average preoperative bone conduction and air conduction pure tone averages were 19.6 dB (SD 15.6 dB) and 55.9 dB (SD 23.6 dB), respectively. The average air-bone gap was 36.3 dB (SD 17.9 dB) preoperatively. In the seven patients who underwent preoperative CT, all were consistently identified to have an absent or hypoplastic pyramidal eminence and absent stapedial tendon aperture at the pyramidal eminence. In six cases, the stapedial footplate appeared normal, while in one case the footplate appeared abnormal which correlated with severe facial nerve prolapse observed intraoperatively. All eight cases underwent exploratory tympanotomy and demonstrated intraoperative stapes footplate fixation, absent stapedial tendon and either absent or hypoplastic pyramidal eminence, which correlated with preoperative CT findings.

CONCLUSIONS

This study identifies a clinically pragmatic association between an absent pyramidal eminence identified on high-resolution CT and the diagnosis of CSFF. In a condition that otherwise generally lacks distinctive radiological features, the absence of a pyramidal eminence on CT in a patient with nonprogressive, congenital conductive hearing loss may strengthen clinical suspicion for CSFF.

Increased flexor hallucis longus tension decreases ankle dorsiflexion

BACKGROUND

Restricted excursion of the flexor hallucis longus (FHL) is associated with several clinical problems. An FHL excursion measurement device (EMD) was used to objectively assess differences between patients with clinically normal or tight FHL tendons.

METHODS

188 patients (356 feet) were enrolled. The EMD measured maximum ankle dorsiflexion with the great toe in 15°, 30°, and 45° of dorsiflexion. All had clinical assessment of FHL tightness by their provider independently of the EMD measurement.

RESULTS

Increased hallux DF always caused decreased ankle DF. Patients with clinically tight FHLs demonstrated decreased ankle DF compared to normal subjects at all hallux positions (p<0.01). The EMD measurement was not sensitive enough for detection of FHL tightness in individuals. A clinically tight FHL was seen in almost 50% of feet.

CONCLUSIONS

Tension in the FHL can limit ankle DF. Clinical tightness of the FHL is likely more common than currently recognized.

Posttraumatic triggering of the extensor pollicis brevis tendon in de Quervain's disease successfully diagnosed with ultrasonography: A case report

Triggering due to de Quervain's disease is exceedingly rare. This is the first successfully diagnosed case of the snapping phenomenon of the extensor pollicis brevis (EPB) tendon in de Quervain's disease evaluated with preoperative dynamic ultrasonography, clearly demonstrated in an intraoperative video, and treated with decompression of EPB subcompartment only under a wide-awake surgery. Dynamic ultrasonographic images identified snapping caused by unsmooth excursion of an enlarged EPB tendon in a separate subcompartment. In snapping de Quervain's disease, ultrasonographic evaluations and wide-awake surgery are essential to exactly diagnose and successfully treat the snapping condition of the EPB and/or APL tendons.

Compensatory Movement Patterns Are Based on Abnormal Activity of the Biceps Brachii and Posterior Deltoid Muscles in Patients with Symptomatic Rotator Cuff Tears

BACKGROUND

Abnormal movement patterns due to compensatory mechanisms have been reported in patients with rotator cuff tears. The long head of the biceps tendon may especially be overactive and a source of pain and could induce abnormal muscle activation in these patients. It is still unknown why some patients with a rotator cuff tear develop complaints and others do not.

QUESTIONS/PURPOSES

(1) Which shoulder muscles show a different activation pattern on electromyography (EMG) while performing the Functional Impairment Test-Hand and Neck/Shoulder/Arm (FIT-HaNSA) in patients with a symptomatic rotator cuff tear compared with age-matched controls with an intact rotator cuff? (2) Which shoulder muscles are coactivated on EMG while performing the FIT-HaNSA?

METHODS

This comparative study included two groups of people aged 50 years and older: a group of patients with chronic symptomatic rotator cuff tears (confirmed by MRI or ultrasound with the exclusion of Patte stage 3 and massive rotator cuff tears) and a control group of volunteers without shoulder conditions. Starting January 2019, 12 patients with a chronic rotator cuff tear were consecutively recruited at the outpatient orthopaedic clinic. Eleven age-matched controls (randomly recruited by posters in the hospital) were included after assuring the absence of shoulder complaints and an intact rotator cuff on ultrasound imaging. The upper limb was examined using the FIT-HaNSA (score: 0 [worst] to 300 seconds [best]), shoulder-specific instruments, health-related quality of life, and EMG recordings of 10 shoulder girdle muscles while performing a tailored FIT-HaNSA.

RESULTS

EMG (normalized root mean square amplitudes) revealed hyperactivity of the posterior deltoid and biceps brachii muscles during the upward phase in patients with rotator cuff tears compared with controls (posterior deltoid: 111% ± 6% versus 102% ± 10%, mean difference -9 [95% confidence interval -17 to -1]; p = 0.03; biceps brachii: 118% ± 7% versus 111% ± 6%, mean difference -7 [95% CI -13 to 0]; p = 0.04), and there was decreased activity during the downward phase in patients with rotator cuff tears compared with controls (posterior deltoid: 89% ± 6% versus 98% ± 10%, mean difference 9 [95% CI 1 to 17]; p = 0.03; biceps brachii: 82% ± 7% versus 89% ± 6%, mean difference 7 [95% CI 0 to 14]; p = 0.03). The posterior deltoid functioned less in conjunction with the other deltoid muscles, and lower coactivation was seen in the remaining intact rotator cuff muscles in the rotator cuff tear group than in the control group.

CONCLUSION

Patients with a symptomatic rotator cuff tear show compensatory movement patterns based on abnormal activity of the biceps brachii and posterior deltoid muscles when compared with age-matched controls. The posterior deltoid functions less in conjunction with the other deltoid muscles, and lower coactivation was seen in the remaining intact rotator cuff muscles in the rotator cuff tear group than the control group.

CLINICAL RELEVANCE

This study supports the potential benefit of addressing the long head biceps tendon in the treatment of patients with a symptomatic rotator cuff tear. Moreover, clinicians might use these findings for conservative treatment; the posterior deltoid can be specifically trained to help compensate for the deficient rotator cuff.

Tendon release reduced joint stiffness with unaltered leg stiffness during gait in spastic diplegic cerebral palsy

Biomechanical deviations at individual joints are often identified by gait analysis of patients with cerebral palsy (CP). Analysis of the control of joint and leg stiffness of the locomotor system during gait in children with spastic diplegic CP has been used to reveal their control strategy, but the differences between before and after surgery remain unknown. The current study aimed to bridge the gap by comparing the leg stiffness—both skeletal and muscular components—and associated joint stiffness during gait in 12 healthy controls and 12 children with spastic diplegic CP before and after tendon release surgery (TRS). Each subject walked at a self-selected pace on a 10-meter walkway while their kinematic and forceplate data were measured to calculate the stiffness-related variables during loading response, mid-stance, terminal stance, and pre-swing. The CP group altered the stiffness of the lower limb joints and decreased the demand on the muscular components while maintaining an unaltered leg stiffness during stance phase after the TRS. The TRS surgery improved the joint and leg stiffness control during gait, although residual deficits and associated deviations still remained. It is suggested that the stiffness-related variables be included in future clinical gait analysis for a more complete assessment of gait in children with CP.

Dysregulated assembly of elastic fibers in fibulin-5 knockout mice results in a tendon-specific increase in elastic modulus

Elastic fiber assembly is coordinated in part by fibulin-5, a matricellular protein. When fibulin-5 is not available to guide elastogenesis, elastin forms into disconnected globules instead of the dense elastic fiber core found in healthy tissues. Despite the growing evidence for a significant role of elastic fibers in tendon mechanics and the clinical relevance to cutis laxa, a human disease which can be caused by a mutation in the gene encoding fibulin-5, it is unknown how malformed elastic fibers affect tendon function. Therefore, this study investigated the effects of dysregulated elastic fiber assembly in tendons from fibulin-5 knockout mice in comparison to wild-type controls. Due to evidence for a more prominent role of elastic fibers in tendons with higher functional demands, both the energy-storing Achilles tendon and the more positional tibialis anterior tendon were evaluated. The linear modulus of knockout Achilles tendons was increased compared to controls, yet there was no discernible change in mechanical properties of the tibialis anterior tendon across genotypes. Transmission electron microscopy confirmed the presence of malformed elastic fibers in knockout tendons while no other changes to tendon composition or structure were found. The mechanism behind the increase in linear modulus in fibulin-5 knockout Achilles tendons may be greater collagen engagement due to decreased regulation of strain-induced structural reorganization. These findings support the theory of a significant, functionally distinct role of elastic fibers in tendon mechanics.

Tendinopathies of the foot and the ankle : from the anatomy to the clinic

The tendons of the foot and the ankle are divided into four compartments (posterior, medial, lateral and anterior). They can be the seat of tendinopathies. The term of "tendonopathy" was proposed in 1998 to group the clinical syndrome defined by pain, tendon edema and functional disability. Tendinopathies can be of traumatic origin, inflammatory and we speak about tendinitis, mechanical by hypersollicitation or iatrogenic. The diagnosis of these tendinopathies requires a precise knowledge of the basic anatomical notions and is based on three positive signs, which are the direct tendon palpation pain, passive tendon stretching pain and pain in the contraction of the muscle. The calcaneal tendonopathy is the most frequent.

Rebuilding Tendons: A Concise Review on the Potential of Dermal Fibroblasts

Tendons are vital to joint movement by connecting muscles to bones. Along with an increasing incidence of tendon injuries, tendon disorders can burden the quality of life of patients or the career of athletes. Current treatments involve surgical reconstruction and conservative therapy. Especially in the elderly population, tendon recovery requires lengthy periods and it may result in unsatisfactory outcome. Cell-mediated tendon engineering is a rapidly progressing experimental and pre-clinical field, which holds great potential for an alternative approach to established medical treatments. The selection of an appropriate cell source is critical and remains under investigation. Dermal fibroblasts exhibit multiple similarities to tendon cells, suggesting they may be a promising cell source for tendon engineering. Hence, the purpose of this review article was in brief, to compare tendon to dermis tissues, and summarize in vitro studies on tenogenic differentiation of dermal fibroblasts. Furthermore, analysis of an open source Gene Expression Omnibus (GEO) data repository was carried out, revealing great overlap in the molecular profiles of both cell types. Lastly, a summary of in vivo studies employing dermal fibroblasts in tendon repair as well as pilot clinical studies in this area is included. Altogether, dermal fibroblasts hold therapeutic potential and are attractive cells for rebuilding injured tendons.

Kinetic dysfunction of the wrist with chronic scapholunate dissociation. A cadaver study

BACKGROUND

Most laboratory studies investigating scapholunate dissociations are based on normal cadaver arms with serially sectioned ligaments. It is assumed that the kinetic behavior of a ligament-sectioned wrist is similar to a scapholunate dissociation. We tested five cadaver wrists with real injuries. The goal of this research was to evaluate the biomechanical behavior of scapholunate advanced collapse wrists compared to an experimental group with simulated injuries.

METHODS

Using a magnetic 6-degree of freedom motion tracking device, changes in scaphoid alignment induced by isometric loading 5 wrist motor tendons in two groups of specimens were monitored. Twelve fresh cadaver wrists in which scapholunate injury was simulated by sectioning the scapholunate ligament were compared to 5 arms with chronic scapholunate dissociation.

FINDINGS

The behavior of the scaphoid is the same in both groups, but the magnitude of displacement is greater in chronic scapholunate dissociation wrists, although not statistically significant. The extensor carpi ulnaris is the only muscle that provokes scaphoid pronation; all other muscles induce its supination.

INTERPRETATION

Different factors may play a role in the amount of scaphoid rotation observed in wrists with chronic scapholunate dissociation. Ligament sectioning alone in the experimental setup can only partially replicate the behavior of real scapholunate dissociations. The extensor carpi ulnaris has a major role in destabilizing scapholunate advanced collapse wrists; therefore, isometric contraction of this muscle should be avoided in the conservative treatment. The experimental setup designed is useful to evaluate the biomechanical behavior of the carpus under traction load.

The split transfer of tibialis anterior tendon to peroneus tertius tendon for equinovarus foot in children with cerebral palsy

OBJECTIVE

The aim of this study was to analyze the results of the split anterior tibialis tendon transfer (SPLATT) to peroneus tertius (PT) for equinovarus foot deformity in children with cerebral palsy (CP).

METHODS

The medical records of 25 ambulatory CP patients (mean age: 8.7±3.2 years, range: 4-16 years) with equinovarus foot (33 feet), who underwent SPLATT to PT surgery between 2014 and 2016, were retrospectively reviewed. A senior surgeon performed all the surgical procedures. SPLATT was performed as part of a single-event multilevel surgery for the lower limb, and the concomitant procedures on the same extremity were recorded. The patients who required any additional foot or ankle surgery that could affect the clinical outcome (except heel cord lengthening) were excluded from the study. The Kling's College Criteria were used to evaluate the procedural outcome of the foot position and gait, and the associated complications were recorded.

RESULTS

The mean follow-up time was 28.8±5 months (range: 24-42 months). The postoperative Kling scores were excellent for 27 feet of the patients who had a plantigrade foot, without fixed or postural deformity, in a regular shoe, having no calluses; good for 5 cases for those who walked with less than 5° varus, valgus, or equinus posture of the hind foot, wearing regular shoes, having no callosities; and fair for 1 case for those who had recurrence of the deformity. There was only one wound detachment, which was treated with wound care and dressing. None of the patients had overcorrection, infection, or bone fracture.

CONCLUSION

The dynamic SPLATT to PT surgery for the management of the equinovarus foot deformities in the CP patients is a safe and less complicated surgical alternative with a good functional outcome. It is a safe and effective treatment method for the management of equinovarus foot deformities in CP.

LEVEL OF EVIDENCE

Level IV, Therapeutic study.

[Professor CHEN Ri-xin's academic idea of "pain in joint and disorder in tendon region of meridian" and its clinical application for knee arthralgia]

Professor CHEN Ri-xin's academic idea of "pain in joint and disorder in tendon region of meridian" was explored in this paper. According to the particular characteristics of the occurrence and development of the disease, knee arthralgia is divided into 4 stages, named tendon spasm, tendon blockage, tendon contraction and tendon atrophy. It is proposed that "tendon disorder results in bone disorder", implying the relationship between the disorders of tendon and bone. It is pointed that yang qi insufficiency occurs throughout knee arthralgia. "The tendon disorder should be treated at the first-line procedure for the bone disorder, and the tendon softening benefits the recovery of knee joints". The treatment principle includes "removing obstruction from meridian, eliminating pathogen, warming up yang and softening tendon". In clinical application, the heat-sensitive moxibustion is predominated. The various regimens are developed align with the pathogenesis characteristics of the disease at different stages.

"Swiss roll"-like bioactive hybrid scaffolds for promoting bone tissue ingrowth and tendon-bone healing after anterior cruciate ligament reconstruction

The choice of grafts for anterior cruciate ligament (ACL) reconstruction is a critical issue in sports medicine. Previous studies have revealed that scaffolds prepared from a single material could not achieve complete integration between the graft and autogenous bone tunnel. To solve this problem, we hypothesize that combining degradable scaffolds with nondegradable scaffolds can produce a novel hybrid ligament with the advantages of both types of scaffolds. In this study, a bone morphogenetic protein 7 (BMP-7)-loaded polycaprolactone (PCL) nanofibrous membrane was first manufactured as the degradable part of the hybrid ligament by using layer-by-layer (LbL) self-assembly. Then, we fabricated a multifunctional novel hybrid ligament by rolling up this nanofibrous membrane and polyethylene terephthalate (PET) mesh fabric (nondegradable part) into a "swiss roll" structure. The in vitro experimental results showed that this hybrid ligament could significantly improve the biocompatibility of pure PET ligament and further promote cell mineralization. The in vivo experimental results showed that this unique structure significantly promoted the integration of hybrid ligaments and bone tunnels, thereby achieving real "ligamentization" after ACL reconstruction surgery. These results suggest that this novel hybrid biomimetic artificial ligament scaffold provides a new direction for graft selection for ACL reconstruction.

Increased Stiffness of Rotator Cuff Tendons in Frozen Shoulder on Shear Wave Elastography

OBJECTIVES

To evaluate the stiffness and morphologic characteristics of the capsule, rotator cuff tendons and muscles, coracohumeral ligament (CHL), and long head of the biceps in patients with frozen shoulder using shear wave elastography (SWE) with B-mode ultrasound.

METHODS

Thirty-two patients with frozen shoulder were divided into freezing and frozen phases. All patients had limitations of their range of motion without rotator cuff tears. Stiffness was measured by SWE in the supraspinatus (SSp) tendon, infraspinatus (ISp) tendon, SSp muscle, ISp muscle, teres minor muscle, upper and lower trapezius muscles, posterior capsule, CHL, and long head of the biceps. The posterior capsule and CHL thicknesses were also investigated with B-mode ultrasound. All values were compared in the affected and unaffected shoulders in each phase.

RESULTS

The SWE values for the SSp and ISp tendons in the freezing phase and the CHL in the frozen phase were significantly greater on the affected side than the unaffected side (mean ± SD, 280.4 ± 125.3 versus 178.1 ± 73.3, 318.4 ± 110.7 versus 240.8 ± 91.5, and 287.2 ± 135.3 versus 214.1 ± 91.1 kPa, respectively; P < .05). The posterior capsule in both the freezing and frozen phases and the CHL in the frozen phase were significantly thicker on the affected side than the unaffected side (1.3 ± 0.2 versus 0.9 ± 0.3, 1.2 ± 0.4 versus 0.9 ± 0.3, and 4.4 ± 1.4 versus 3.3 ± 1.1 mm; P < .01).

CONCLUSIONS

The SWE values of the both SSp and ISp tendons increased in the freezing phase, and that of the CHL also increased in the frozen phase. Not only the change in thickness of the capsule but also the change in stiffness of the rotator cuff may correlate with frozen shoulder.

In situ tissue engineering of the tendon-to-bone interface by endogenous stem/progenitor cells

The long-term success of surgical repair of rotator cuff tears is largely dependent on restoration of a functional tendon-to-bone interface. We implemented micro-precise spatiotemporal delivery of growth factors in three-dimensional printed scaffolds for integrative regeneration of a fibrocartilaginous tendon-to-bone interface. Sustained and spatially controlled release of tenogenic, chondrogenic and osteogenic growth factors was achieved using microsphere-based delivery carriers embedded in thin membrane-like scaffolds. In vitro, the scaffolds embedded with spatiotemporal delivery of growth factors successfully guided regional differentiation of mesenchymal progenitor cells, forming multiphase tissues with tendon-like, cartilage-like and bone-like regions. In vivo, when implanted at the interface between the supraspinatus tendon and the humeral head in a rat rotator cuff repair model, these scaffolds promoted recruitment of endogenous tendon progenitor cells followed by integrative healing of tendon and bone via re-formation of strong fibrocartilaginous interfaces. Our findings demonstrate the potential of in situ tissue engineering of tendon-to-bone interfaces by endogenous progenitor cells. The in situ tissue engineering approach shows translational potential for improving outcomes after rotator cuff repair.

The Effect of Extensor Tendon Adhesions on Finger Motion

PURPOSE

To quantify the amount and pattern of finger range of motion loss at the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints with a simulated extensor tendon adhesion at the level of the proximal phalanx or metacarpal.

METHODS

In 10 cadaveric specimens, traction sutures were placed in the forearm extensor digitorum communis and flexor digitorum profundus tendons of the middle and ring fingers. Active motion was simulated by suspending weights from the traction sutures via pulleys. The angles of the MCP, PIP, and DIP joints were measured at the position of maximum flexion and extension. Extensor tendon adhesions were simulated alternately at the proximal phalanx and metacarpal levels of the middle and ring fingers, using suture anchors. Repeat measurements were taken using the same amount of force.

RESULTS

There was an average total loss of flexion of 38° and of extension of 6° with a proximal phalanx adhesion, with a greater contribution of flexion loss at the PIP joint. The loss of flexion was 17° and of extension was 50° with a metacarpal adhesion, with a loss of extension mostly at the MCP joint.

CONCLUSIONS

The results of this study identified clear patterns of motion loss that are associated with isolated simulated adhesions in different locations along the extensor mechanism. The greatest motion loss occurred at the joint immediately distal to the simulated adhesion.

CLINICAL RELEVANCE

Although extrapolation of these findings to clinical relevance remains unclear, the ability to predict the level of adhesion by the pattern of motion restriction may allow for a targeted tenolysis procedure. This would reduce the amount of soft tissue dissection required, which in turn, could be expected to reduce the degree of repeat adhesion formation.

HMGB1 mediates the development of tendinopathy due to mechanical overloading

Mechanical overloading is a major cause of tendinopathy, but the underlying pathogenesis of tendinopathy is unclear. Here we report that high mobility group box1 (HMGB1) is released to the tendon extracellular matrix and initiates an inflammatory cascade in response to mechanical overloading in a mouse model. Moreover, administration of glycyrrhizin (GL), a naturally occurring triterpene and a specific inhibitor of HMGB1, inhibits the tendon’s inflammatory reactions. Also, while prolonged mechanical overloading in the form of long-term intensive treadmill running induces Achilles tendinopathy in mice, administration of GL completely blocks the tendinopathy development. Additionally, mechanical overloading of tendon cells in vitro induces HMGB1 release to the extracellular milieu, thereby eliciting inflammatory and catabolic responses as marked by increased production of prostaglandin E₂ (PGE₂) and matrix metalloproteinase-3 (MMP-3) in tendon cells. Application of GL abolishes the cellular inflammatory/catabolic responses. Collectively, these findings point to HMGB1 as a key molecule that is responsible for the induction of tendinopathy due to mechanical overloading placed on the tendon.

The proximal hamstring avulsion clinical trial (PHACT)-a randomised controlled non-inferiority trial of operative versus non-operative treatment of proximal hamstrings avulsions: study protocol

INTRODUCTION

The treatment of proximal hamstring avulsions is controversial. While several trials have investigated the outcome for patients treated surgically, there is today no prospective trial comparing operative treatment with non-operative treatment. This protocol describes the design for the proximal hamstring avulsion clinical trial (PHACT)-the first randomised controlled trial of operative versus non-operative treatment for proximal hamstring avulsions.

METHODS AND ANALYSIS

PHACT is a multicentre randomised controlled trial conducted across Sweden, Norway and Finland. Eligible patients (60 participants/treatment arm) with a proximal hamstring avulsion of at least two of three tendons will be randomised to either operative or non-operative treatment. Participants allocated to surgery will undergo reinsertion of the tendons with suture anchors. The rehabilitation programme will be the same for both treatment groups. When patient or surgeon equipoise for treatment alternatives cannot be reached and randomisation therefore is not possible, patients will be invited to participate in a parallel observational non-randomised cohort. The primary outcome will be the patient-reported outcome measure Perth hamstring assessment tool at 24 months. Secondary outcomes include the Lower Extremity Functional Score, physical performance and muscle strength tests, patient satisfaction and MR imaging. Data analysis will be blinded and intention-to-treat analysis will be preformed.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Ethical Committee of Uppsala University (DNR: 2017-170) and by the Norwegian ethical board (REC: 2017/1911). The study will be conducted in agreement with the Helsinki declaration. The findings will be disseminated in peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT03311997.

Body Mass Index and Segmental Mass Correlation With Elastographic Strain Ratios of the Quadriceps Tendon

OBJECTIVES

The aim of this study was to establish a relationship between quadriceps tendon stiffness and its properties and variations in the body mass index (BMI) and segmental mass.

METHODS

This study was conducted in 3 groups according to their BMI (A, low [<18.5 kg/m² ]; B, normal [18.5-25.0 kg/m² ]; and C, high [>25.0 kg/m² ]). All of the participants included had a sedentary lifestyle and did not do any weightlifting or any kind of sports activity in the previous 6 months. Ultrasound measurements were performed on the participants' lower right extremities, since it was the dominant side for all of the participants.

RESULTS

A total of 40 healthy untrained men participated in the study. The mean age of the participants ± SD was 22.1 ± 1.3 years; the age ranges for groups A (n = 6), B (n = 18), and C (n = 16) were 19-23, 19-25, and 20-25 years, respectively; 28 of the participants were nonsmokers, and 12 of were smokers. A strong statistical difference (all P < .05) was witnessed for most of the parameters (BMI, body fat mass, dominant leg body fat content, fat-free mass index, tendon thickness, and strain ratio) among the groups.

CONCLUSIONS

The length of the tendon did not show a significant increase with an increase in the BMI, body fat mass, dominant leg body fat content, and fat-free mass index. However, a greater intensification was observed for the thickness of the tendon with a significant increase in tendon stiffness (with the use of external reference material).

Synthetic Mesh Allograft Reconstruction for Extensor Mechanism Insufficiency After Knee Arthroplasty

Extensor mechanism (EM) insufficiency after knee arthroplasty is a rare but devastating complication resulting in severe disability. To date, primary repair and allograft reconstructive options have produced suboptimal results. A synthetic mesh allograft reconstruction technique has recently been introduced with promising outcomes. A retrospective chart review was performed to identify all patients who experienced EM failure after total or unicompartmental knee arthroplasty and subsequently underwent synthetic mesh EM reconstruction using a previously described technique. Patient demographics, pre- and postoperative knee range of motion and residual extensor lag, pre- and postoperative pain and functional outcome scores, and complications were extracted during the chart review. Twelve patients met inclusion criteria: 3 with patellar tendon and 9 with quadriceps tendon defects. At mean follow-up of 27.0 months, all patients were ambulatory, with a mean residual extensor lag of 12.9° (range, 0°-30°). Mean visual analog scale pain score decreased significantly after EM reconstruction: 4.6±2.3 (range, 1-8) preoperatively vs 1.8±2.4 (range, 0-7) postoperatively (P=.01). The mean Knee Society knee score improved from 41.5±11.1 (range, 21-57) preoperatively to 79.5±13.8 (range, 54-90) postoperatively (P<.0001). The mean Knee Society function score improved from 14.6±12.3 (range, 0-40) preoperatively to 64.2±27.1 (range, 5-95) postoperatively (P<.0001). One clinical failure occurred as a result of prosthetic joint infection. Synthetic mesh EM reconstruction effectively restores knee function for a variety of EM deficiencies following knee arthroplasty. [Orthopedics. 2019; 42(4):e385-e390.].

Tendon Subluxation After Surgical Release of the First Dorsal Compartment in De Quervain Disease

We aimed to determine whether dorsoulnar incision elevating radial flap and immobilization for the treatment of de Quervain disease have an advantage over simple midline incision and early mobilization, respectively, in terms of tendon subluxation and clinical outcomes. Forty-six patients with de Quervain disease were randomly divided into 2 groups (midline incision vs dorsoulnar incision) and 2 subgroups (immobilization vs early mobilization). Subluxation of intracompartmental tendons was measured in dynamic wrist positions at 12 and 24 weeks using ultrasonography. The DASH (Disabilities of the Arm, Shoulder, and Hand) and visual analog scale scores and grip and pinch strengths were evaluated. At 24 weeks, the tendons were displaced voloradially in wrist volar flexion (1.25 mm in midline incision vs 0.36 mm in dorsoulnar incision, P = 0.001), whereas the tendons were displaced dorsoulnarly in wrist extension (0.95 mm in midline incision vs 1.78 mm in dorsoulnar incision, P = 0.041). There were no significant differences in tendon displacement between early mobilization and immobilization groups. Clinical outcome measures showed no variation between the groups, and no significant correlation occurred with tendon subluxation. Dorsoulnar incision and postoperative immobilization do not have advantage over midline incision and early mobilization, respectively. However, tendon subluxation after release of the first dorsal compartment for de Quervain disease does not affect clinical outcomes.

Ultrasound Features of the Proximal Hamstring Muscle-Tendon-Bone Unit

The hamstring muscle complex is made by a group of posterior biarticular thigh muscles, originating at the ischial tuberosity, which extend the hip and flex the knee joint. Proximal hamstring injuries are frequent among athletes, commonly involving their long myotendinous junction during an eccentric contraction. In this pictorial essay, we describe the ultrasound technique to visualize the normal anatomy of the proximal hamstring muscle-tendon-bone complex and present ultrasound findings in patients with traumatic injuries and tendinopathies.

Effects of tendon injury on uninjured regional tendons in the distal limb: An in-vivo study using an ovine tendinopathy model

Following injury to a tendon little is known about potential for pathology to develop in other regional tendons from overloading or altered function. The aim of this study was to investigate the gene expression and histopathological changes that occur 1) within the deep digital flexor tendon (DDFT) after injury to the superficial digital flexor tendon (SDFT) and 2) within the flexor tendons (SDFT and DDFT) after injury to the extensor tendons. Merino wethers [Ovis aries] (n = 18) were divided into three equal groups and underwent either partial transection of the SDFT, complete transection of the extensor tendons or were left as non-operated controls. Tendons were harvested and sampled regionally for gene expression (real time PCR) and histologic analysis eight weeks after surgery. Transection of the SDFT resulted in increased expression of collagen III, versican, biglycan, lumican and MMP1 (P<0.026 for all genes) within the DDFT. There was no effect of transecting the extensor tendons on the expression of any gene tested in either the SDFT or the DDFT. The DDFT had elevated histopathology scores induced by transection of the SDFT, eight weeks previously. There were minimal histological differences in either the SDFT or DDFT after transection of the extensor tendons. Transection of the SDFT results in a mild, subclinical tendinopathy within the DDFT with potential implications on treatment and rehabilitation of SDFT injuries. Injury to the extensor tendons has minimal measured effect on the SDFT or DDFT.

Reliability of quantitative point shear-wave ultrasound elastography on vastus medialis muscle and quadriceps and patellar tendons

AIM

The aim of this work was to evaluate the reliability of pSWE in assessing the stiffness of the vastus medialis muscle and of the quadriceps and patellar tendons.

MATERIAL AND METHODS

For this purpose, 18 subjects (9 males and 9 females of 57±22 years) in good clinical conditions were included in this study. pSWE examination was conducted by a unique expert operator with more than ten years of experience in musculoskeletal ultrasound. Two sets of five measurements for each muscle and tendon district were bilaterally performed at the same manner, at least fifteen minutes apart. The mean value of the measurements of each set was statistically compared with that of the other set.

RESULTS

No significant differences were found comparing the mean value of the measurements of the two sets of evaluation performed in muscle and tendon areas (vastus medialis muscle: p=0.285; quadriceps tendon: p=0.979; patellar tendon: p=0.187). The intraclass correlation coefficient was excellent for all areas (vastus medialis muscle: 0.969; quadriceps and patellar tendons: 0.995 and 0.989, respectively).

CONCLUSION

 The pSWE technique demonstrated that it was a reliable method for measuring stiffness in vastus medialis muscle and quadriceps and patellar tendon in subjects who had undergone orthopedic surgery. This opens the possibility of many applications in monitoring stiffness before and after surgery and during rehabilitation.

Ultrasound Features of Palmar Fibromatosis or Dupuytren Contracture

OBJECTIVES

To retrospectively characterize the ultrasound appearance of palmar fibromatosis in patients with a surgical or clinical diagnosis of palmar fibromatosis.

METHODS

A search of ultrasound reports from 2005 to 2015 and a subsequent search of medical records were performed to identify patients with a surgical or clinical diagnosis of palmar fibromatosis. The ultrasound images were retrospectively reviewed to record the lesion location, size, echogenicity, compressibility, hyperemia, and calcification.

RESULTS

A total of 36 patients were identified (average age, 60 years; 61% male), yielding a total of 55 palmar fibromatosis lesions, of which 2%, 7%, 29%, 36%, 20%, and 5% were located at the first, second, third, fourth, and fifth digits and between the fourth and fifth digits, respectively. The lesions were located directly superficial to the flexor tendons in 93% with their epicenters at the distal metacarpal in 89%. Average lesion dimensions were 13.1 mm in length, 6.8 mm in width, and 2.5 mm in depth. On ultrasound images, the lesions were characteristically hypoechoic (98%) and noncompressible (95%). Atypical features included calcification (2%), compressibility (5%), hyperemia on color Doppler images (6%), epicenters at the metacarpophalangeal joint (7%) or proximal phalanx (4%), and location superficial but lateral to the flexor tendons (7%).

CONCLUSIONS

Palmar fibromatosis most commonly appears hypoechoic and is located directly superficial to the flexor tendons with an epicenter at the distal metacarpal, most commonly the fourth digit. However, the epicenter location may be at the distal metacarpal and proximal phalanx of other digits, adjacent to the flexor tendons, with possible hyperemia and calcification.

Book-Shaped Acellular Fibrocartilage Scaffold with Cell-loading Capability and Chondrogenic Inducibility for Tissue-Engineered Fibrocartilage and Bone-Tendon Healing

Functional fibrocartilage regeneration is a bottleneck during bone-tendon healing, and the currently available tissue-engineering strategies for fibrocartilage regeneration are insufficient because of a lack of appropriate scaffold that can load large seeding-cells and induce chondrogenesis of stem cells. The acellular fibrocartilage scaffold (AFS) contains active growth factors as well as tissue-specific epitopes for cell-matrix interactions, which make it a potential scaffold for tissue-engineered fibrocartilage. A limitation to this scaffold is that its low porosity inhibits cells loading and infiltration. Here, inspired by book appearance, we sectioned native fibrocartilage tissue (NFT) into book-shape to improve cells loading and infiltration, and then decellularized with four protocols: (1) 2% SDS for 6-h, (2) 2% SDS for 24-h, (3) 4 SDS for 6-h, (4) 4% SDS for 24-h, followed by nuclease digestion. The optimal protocol was screened with respect to microstructures, DNA residence, native ingredients reservation, and chondrogenic inducibility of the AFS. In vitro studies demonstrated that this screened scaffold is noncytotoxicity and low-immunogenicity, allows adipose-derived stromal cells (ASCs) attachment and proliferation, shows superior chondrogenic inducibility, and stimulates collagen or glycosaminoglycans secretion. The underlying mechanism for this chondrogenic inducibility may be related to hedgehog pathway activating. Additionally, a novel pattern for fabricating tissue-engineered fibrocartilage was developed to enlarge seeding-cells loading, namely, cell-sheets sandwiched by book-shaped scaffold. In-vivo studies indicate that this screened scaffold alone could induce endogenous cells to satisfactorily regenerate fibrocartilage at 16-week, as characterized by fibrocartilaginous extracellular matrix (ECM) deposition and good interface integration. Interleaving this book-shaped AFS with autologous ASCs-sheets significantly enhanced its ability to regenerate fibrocartilage. Cell tracking demonstrated that fibrochondrocytes, osteoblasts, and osteocytes in the healing interface at postoperative 8-week partly originated from the sandwiched ASCs-sheets. On that basis, we propose the use of this book-shaped AFS and cell sheet technique for fabricating tissue-engineered fibrocartilage to improve bone-tendon healing.

Multiscale mechanisms of tendon fatigue damage progression and severity are strain and cycle dependent

Tendinopathies are common chronic injuries that occur when damage accumulation caused by sub-rupture fatigue loading outpaces repair. Studies have linked fatigue loading with various mechanical, structural, and biological changes associated with pathology. However, the multiscale progression of damage accumulation with respect to area, severity and the distinct contributions of strain level and number of cycles has not been fully elucidated. The objective of this study was to investigate multiscale mechanisms underlying fatigue damage accumulation and their effect on the cellular environment. Using an in situ model in rat tail tendon (RTT), fatigue loading was applied at various strains and cycle numbers to induce fatigue damage. Pre- and post- fatigue diagnostic mechanical testing, second harmonic generation (SHG) imaging, and transmission electron microscope (TEM) imaging were used to investigate extracellular and cellular damage modes at multiple scales. Fatigue loading at strains at or below 1.0% resulted in no significant changes in SHG damage area or severity and no changes in collagen fibril or cell morphology compared with controls. Fatigue loading at strains above 1.5% resulted in greater mechanical changes correlated with increased damage area measured by SHG and collagenous damage observed by TEM. Increased cycles at high strain further altered mechanical properties, increased structural damage severity (but not area), and altered TEM collagen rupture patterns. Cell morphology was similarly progressively affected with increased strain and cycle number. These damage mechanisms that may trigger degenerative changes characteristic of tendinopathy could be targeted as a part of prevention or therapy.

Trigger finger secondary to a neglected flexor tendon rupture

Secondary trigger finger caused by trauma to the hand, especially associated with partial flexor tendon rupture, is not a common condition. Thus, the clinical manifestations of these patients are not well-known. The aim of this study is to present secondary trigger finger caused by a neglected partial flexor tendon rupture including discussion of the mechanism and treatment.We retrospectively reviewed the records of 6 patients with trigger finger caused by a neglected partial flexor tendon rupture who had been treated with exploration, debridement, and repairing of the ruptured tendon from August 2010 to May 2015. The average patient age was 41 years (range, 23-59). The time from injury to treatment averaged 4.7 months. The average follow-up period was 9 months (range, 4-18). Functional outcome was evaluated from a comparison between the Quick-disabilities of the arm, shoulder, and hand (DASH) score and the visual analogue scale (VAS) for pain, which were measured at the time of preoperation and final follow up.Four patients showed partial rupture of the flexor digitorum profundus (FDP) tendon and 3 showed partial rupture of the flexor digitorun superficialis (FDS) tendon. Both the FDP and FDS tendons were partially ruptured in 2 patients, and the remaining patient had a partial rupture of the flexor pollicis longus tendon. All patients regained full range of motion, and there has been no recurrence of triggering. The average VAS score decreased from 3.6 (range, 3-5) preoperatively to 0.3 (range, 0-1) at the final follow up. The average Quick-DASH score decreased from 33.6 preoperatively to 5.3 at the final follow up.When we encounter patients with puncture or laceration wounds in flexor zone 2, even when the injury appears to be simple, partial flexor tendon laceration must be taken into consideration and early exploration is recommended.

A Convenient Non-harm Cervical Spondylosis Intelligent Identity method based on Machine Learning

Cervical spondylosis (CS), a most common orthopedic diseases, is mainly identified by the doctor's judgment from the clinical symptoms and cervical change provided by expensive instruments in hospital. Owing to the development of the surface electromyography (sEMG) technique and artificial intelligence, we proposed a convenient non-harm CS intelligent identify method EasiCNCSII, including the sEMG data acquisition and the CS identification. Faced with the limit testable muscles, the data acquisition method are proposed to conveniently and effectively collect data based on the tendons theory and CS etiology. Faced with high-dimension and the weak availability of the data, the 3-tier model EasiAI is developed to intelligently identify CS. The common features and new features are extracted from raw sEMG data in first tier. The EasiRF is proposed in second tier to further reduce the data dimension, improving the performance. A classification model based on gradient boosted regression tree is developed in third tier to identify CS. Compared with 4 common machine learning classification models, the EasiCNCSII achieves best performance of 91.02% in mean accuracy, 97.14% in mean sensitivity, 81.43% in mean specificity, 0.95 in mean AUC.

Knee sensorimotor control following anterior cruciate ligament reconstruction: A comparison between reconstruction techniques

The sensorimotor system helps to maintain functional joint stability during movement. After anterior cruciate ligament (ACL) injury and reconstruction, several sensorimotor deficits may arise, including altered proprioception and changes in neuromuscular control. It is still unknown whether the type of autograft used in the reconstruction may influence knee sensorimotor impairments. The aim of this study was to comparatively assess the effects of the hamstring tendon (HT) and bone-patellar tendon-bone (BPTB) ACL reconstruction techniques on knee sensorimotor control 6–12 months post-operation. A total of 83 male subjects participated in this study: 27 healthy participants, 30 BPTB-operated patients and 26 HT-operated patients. Active joint position sense in 3 ranges of motion (90–60°, 60–30°, and 30–0° of knee flexion), isometric steadiness, and onset of muscle activation were used to compare sensorimotor system function between groups. Both operated groups had a small (< 5°) but significant joint position sense error in the 30–0° range when compared to the healthy group. No significant differences were found between the operated and the control groups for isometric steadiness or onset of muscle activation. The results of this study suggest that operated patients present knee proprioceptive deficits independently of surgical technique. Nevertheless, the clinical implications of this impairment are still unknown. It seems that selected surgical approach for ACL reconstruction do not affect functioning of the sensorimotor system to a large degree.

Is ultrasonographic enthesitis evaluation helpful for diagnosis of non-radiographic axial spondyloarthritis?

The aim of this study is to evaluate the diagnostic utility of ultrasonographic enthesitis assessment in patients with non-radiographic axial spondyloarthritis (nr-axSpA) and to compare different sonographic scoring methods. Patients with nr-axSpA (n = 30) and mechanical back pain (MBP) (n = 30) were enrolled in the study with standardized clinical criteria. For both of the groups, a total of 18 entheses were evaluated in each patient with B mode ultrasound and power Doppler by a sonographer who is blinded to initial clinical and radiological assessments. Glasgow Ultrasound Enthesitis Scoring System (GUESS), Madrid Sonographic Enthesitis Index (MASEI) and D'Agostino grading system were performed. Intra-rater and inter-rater reliability analyses were evaluated with the intraclass correlation coefficient (ICC). There was at least one enthesitis in 96.7% of patients with nr-axSpA. Median values of the number of enthesitis were 5 in nr-axSpA and 0 in MBP. Mean GUESS total scores were 0.9 in MBP and 4.5 in nr-axSpA. Mean MASEI total scores were 2.3 and 10.5, respectively. The sensitivities were 96.7% and 93.3% for GUESS and MASEI while the detected specificities were 80% for both methods. For Intra-rater reliability analysis, ICC was calculated as 0.981 for GUESS and 0.975 for MASEI, while it was calculated as 0.964 and 0.962 for inter-rater reliability analysis. Thus, evaluation of enthesitis with ultrasound is a reliable, helpful tool for the distinction of patients with nr-axSpA from patients with MBP. We favored the use of MASEI because of assessing upper extremity, using power Doppler and having a correlation with disease activity.

Effects of Tendon Degeneration on Predictions of Supraspinatus Tear Propagation

Rotator cuff tendons undergo degeneration with age, which could have an impact on tear propagation. The objective of this study was to predict tear propagation for different levels of tissue degeneration using an experimentally validated finite element model of a supraspinatus tendon. It was hypothesized that greater amounts of degeneration will result in tear propagation at lower loads than tendons with less degeneration. Using a previously-validated computational model of supraspinatus tendon, 1-cm tears were introduced in the anterior, middle, and posterior thirds of the tendon. Cohesive elements were assigned subject-specific failure properties to model tear propagation, and tendon degeneration ranging from "minimal" to "severe" was modeled by modifying its mechanical properties. Tears in tendons with severe degeneration required the smallest loads to propagate (122-207 N). Posterior tears required greater loads compared to middle and anterior tears at all levels of degeneration. Stress and strain required for tear propagation decreased substantially with degeneration, ranging from 8.5 MPa and 32.6% strain for minimal degeneration and 0.6 MPa and 4.5% strain for severe degeneration. Overall, this work indicates that greater amounts of tendon degeneration lead to greater risk of tear propagation, supporting the need for early detection and treatment of rotator cuff tears.

Ultrasound Diagnosis of Osteophytic Impingement of the Popliteus Tendon After Total Knee Replacement

We report our experience with 6 patients who had total knee replacements with lateral-sided knee pain, referred for ultrasound (US) assessment and US-guided injection. All cases showed an osteophyte within the popliteus sulcus of the lateral femoral condyle impinging on the adjacent tendon. Five of 6 patients reported improvement of symptoms immediately after US-guided injection of an anesthetic and a steroid. Ultrasound has a unique role in the imaging of knee replacements because of its real-time capabilities and absence of artifacts at the popliteus tendon origin.

Dual-layer aligned-random nanofibrous scaffolds for improving gradient microstructure of tendon-to-bone healing in a rabbit extra-articular model

BACKGROUND

Tendon/ligament injuries are common sports injuries. Clinically, the repair of a ruptured tendon or ligament to its bony insertion is needed, but the enthesis structure is not well reestablished following surgical repair. Herein, we fabricated dual-layer aligned-random scaffold (ARS) by electrospinning and aimed to investigate the effect of the scaffold on tendon-to-bone healing in vivo.

MATERIALS AND METHODS

The random and dual-layer aligned-random silk fbroin poly(L-lactic acid-co-e-caprolactone) (P(LLA-CL)) nanofibrous scaffolds were successfully fabricated by electrospinning methods. Ninety New Zealand white rabbits were randomly divided into three groups (random scaffold [RS], ARS, and control groups), and they were subjected to surgery to establish an extra-articular tendon-to-bone healing model with autologous Achilles tendon.

RESULTS

Histological assessment showed that the ARS significantly increased the area of metachromasia, decreased the interface width, and improved collagen maturation and organization at the tendon-bone interface compared with the RS and control groups. Microcomputed tomography analysis showed that the bone tunnel area of RS and ARS groups was significantly smaller than those of the control group. Real-time polymerase chain reaction showed that BMP-2 and osteopontin expression levels of the tissue at the interface between the bone and graft in the RS and ARS groups were higher than those of the control group at 6 weeks. Collagen I expression level of the ARS group was significantly higher than those of the RS and control groups at 6 and 12 weeks. Moreover, the ARS groups had a better ultimate load-to-failure and stiffness than the RS and control groups.

CONCLUSION

ARS could effectively augment the tendon-to-bone integration and improve gradient microstructure in a rabbit extra-articular model by inducing the new bone formation, increasing the area of fibrocartilage, and improving collagen organization and maturation. The dual-layer aligned-random silk fibroin/P(LLA-CL) nanofibrous scaffold is proved to be a promising biomaterial for tendon-to-bone healing.

Treatment of distal radioulnar joint dislocation with spontaneous rupture of extensor tendon by Sauve-Kapandji osteotomy assisted by wrist arthroscopy: A case series and literature review

RATIONALE

Dislocation of the distal radioulnar joint and injury to distal forearm are commonly encountered. However, delayed diagnosis or misdiagnosis has been relatively rare due to improved diagnosis and treatment. Treatment of old dislocation of radioulnar joint is challenging due to development of secondary chronic instability and difficulties in restoration of joint function.

PATIENT CONCERNS

This report describes three cases of patients complained about inability to extend their little fingers.

DIAGNOSES

Local examination and X-ray revealed chronic ulnar joint dislocation.

INTERVENTION

Wrist arthroplasty was used to perform ulnar distal articular cleansing and repair of the triangular fibrocartilage complex (TFCC) articular cartilage. The Sauve-Kapandji osteotomy was performed to treat radial joint dislocation and stabilize ulnar joint. Repair of spontaneous fracture of the extensor tendon was also performed. Postoperative gypsum was used for immobilization for 4 weeks.

OUTCOMES

The follow-up results are reported. Based on Cooney wrist score, the preoperative scores were poor (55, 50, 60), while the post-operative scores were excellent (90, 85, 90) in all 3 cases.

LESSONS

Early and accurate diagnosis and treatment is important for the recovery of distal radius fracture for patients with dislocation of the ulnar joint. The correct treatment determines the degree of later functional recovery. Early surgical treatment is recommended for patients with unsatisfactory reset. Delayed diagnosis and treatment often lead to chronic and persistent lower ulnar joint subluxation or dislocation, or even osteoarthritis. All patients in this report showed great improvement in wrist function after surgery.

Evaluation of tendinosis of the long head of the biceps tendon by strain and shear wave elastography

AIM

To investigate strain (SE) and shear wave elastography (SWE) characteristics of the long head of the biceps tendon (LHBT) tendinosis in comparison with magnetic resonance imaging (MRI) findings.

MATERIAL AND METHODS

Twenty patients with a MRI diagnosis of tendinosis and twenty healthy subjects with normal LHBT in MRI were prospectively examined by SE and SWE. SE color mapping was divided into four types in accordance with elasticity designs: type I predominantly blue (hardest tissue), type II predominantly blue-green (hard tissue), type III predominantly green (intermediate tissue), type IV predominantly green-yellow-red (soft tissue). Quantitative measurements of LHBT hardness with SWE were analyzed in kilopascals (kPa).

RESULTS

In the tendinosis group SE types in transverse scan were I in 24% of tendons, II in 50%, III in 25%, and in longitudinal scan I in 15%, II in 75%, and III in 10%. In the control group SE types in transversescan were II in 10% of tendons, III in 55%, IV in 35%, and in longitudinal scan II in 10%, III in 55%, and IV in 35%. SWE values in transverse scan were 38.32±7.2 kPa in the tendinosis group and 18.6±3.1 kPa in the control groupand in longitudinal scan 39.42±7.4 kPa in the tendinosis group, and 20.62±4.6 in the control group. There was a statistically significant difference in terms of elasticity patterns between the tendinosis and control groups (p<0.001). The receiver operating characteristic curve analysis was perfect and a cut-off value of tranverse 25.8 kPa and longitudinal, 24.6 kPa shear values had very high sensitivity and specificity for tendinosis.

CONCLUSION

SE and SWE may be useful diagnostic tools for LHBT tendinosis when considering usability, cost effectiveness, and patient preference compared to MRI.

Nanoanalytical electron microscopy of events predisposing to mineralisation of turkey tendon

The macro- and micro-structures of mineralised tissues hierarchy are well described and understood. However, investigation of their nanostructure is limited due to the intrinsic complexity of biological systems. Preceding transmission electron microscopy studies investigating mineralising tissues have not resolved fully the initial stages of mineral nucleation and growth within the collagen fibrils. In this study, analytical scanning transmission electron microscopy and electron energy-loss spectroscopy were employed to characterise the morphology, crystallinity and chemistry of the mineral at different stages of mineralization using a turkey tendon model. In the poorly mineralised regions, calcium ions associated with the collagen fibrils and ellipsoidal granules and larger clusters composed of amorphous calcium phosphate were detected. In the fully mineralised regions, the mineral had transformed into crystalline apatite with a plate-like morphology. A change in the nitrogen K-edge was observed and related to modifications of the functional groups associated with the mineralisation process. This transformation seen in the nitrogen K-edge might be an important step in maturation and mineralisation of collagen and lend fundamental insight into how tendon mineralises.

Reported selection criteria for adult acquired flatfoot deformity and posterior tibial tendon dysfunction: Are they one and the same? A systematic review

BACKGROUND

Posterior tibial tendon dysfunction (PTTD) and adult acquired flatfoot deformity (AAFD) are used interchangeably, although both suggest quite different pathological processes.

OBJECTIVE

To investigate key differences in selection criteria used for inclusion into research studies.

METHODS

An electronic database search was performed from inception to June 2016. All primary research articles with clear inclusion/diagnostic criteria for PTTD or AAFD were included in the review. All criteria were extracted and synthesised into one aggregate list. Frequencies of recurring criteria were calculated and reported for each stage of the conditions.

RESULTS

Of the potentially eligible papers, 148 (65%) did not specify inclusion/selection criteria for PTTD or AAFD and were excluded. Eligibility criteria were reported 82 times in the 80 included papers, with 69 descriptions for PTTD and 13 for AAFD. After synthesis of criteria from all papers, there were 18 key signs and symptoms. Signs and symptoms were considered to be those relating to tendon pathology and those relating to structural deformity. The total number of individual inclusion/diagnostic criteria ranged from 2 to 9. The majority of articles required signs of both tendon dysfunction and structural deformity (84% for AAFD and 81% for PTTD). Across both groups, the most frequently reported criteria were abduction of the forefoot (11.5% of total criteria used), the presence of a flexible deformity (10.2%) and difficulty performing a single leg heel raise (10.0%). This was largely the case for the PTTD articles, whereas the AAFD articles were more focused on postural issues such as forefoot abduction, medial arch collapse, and hindfoot valgus (each 16.7%).

CONCLUSION

As well as synthesising the available literature and providing reporting recommendations, this review has identified that many papers investigating PTTD/AAFD do not state condition-specific selection criteria and that this limits their clinical applicability. Key signs and symptoms of PTTD and AAFD appear similar, except in early PTTD where no structural deformity is present. We recommend that PTTD is the preferred terminology for the condition associated with signs of local tendon dysfunction with pain and/or swelling along the tendon and difficulty with inversion and/or single leg heel raise characterising stage I and difficulty with single leg heel raise and a flexible flatfoot deformity characterizing stage II PTTD. While AAFD may be useful as an umbrella term for acquired flatfoot deformities, the specific associated aetiology should be reported in studies to aid consolidation and implementation of research into practice.

TRIAL REGISTRATION

Prospero ID: 42016046943.

Evaluation of the performance of three tenodesis techniques for the treatment of scapholunate instability: flexion-extension and radial-ulnar deviation

Chronic scapholunate ligament (SL) injuries are difficult to treat and can lead to wrist dysfunction. Whilst several tendon reconstruction techniques have been employed in the management of SL instability, SL gap reappearance after surgery has been reported. Using a finite element model and cadaveric study data, we investigated the performance of the Corella, scapholunate axis (SLAM) and modified Brunelli tenodesis (MBT) techniques. Scapholunate dorsal and volar gap and angle were obtained following virtual surgery undertaken using each of the three reconstruction methods with the wrist positioned in flexion, extension, ulnar deviation and radial deviation, in addition to the ulnar-deviated clenched fist and neutral positions. From the study, it was found that, following simulated scapholunate interosseous ligament rupture, the Corella technique was better able to restore the SL gap and angle close to the intact ligament for all wrist positions investigated, followed by SLAM and MBT. The results suggest that for the tendon reconstruction techniques, the use of multiple junction points between scaphoid and lunate may be of benefit.

Graphical abstract

Thermo-responsive in-situ forming hydrogels as barriers to prevent post-operative peritendinous adhesion

In this study, we aimed to assess whether thermo-responsive in-situ forming hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) could prevent post-operative peritendinous adhesion. The clinical advantages of the thermo-responsive hydrogels are acting as barrier material to block penetration of fibroblasts, providing mobility and flexibility during application and enabling injection through a small opening to fill spaces of any shape after surgery. The thermo-responsiveness of hydrogels was determined to ensure their clinic uses. By grafting hydrophilic biopolymers chitosan (CS) and hyaluronic acid (HA) to PNIPAM, the copolymer hydrogels show enhanced water retention and lubrication, while reduced volume shrinkage during phase transition. In cell culture experiments, the thermo-responsive hydrogel has good biocompatibility and reduces fibroblast penetration. In animal experiments, the effectiveness of preventing post-operative peritendinous adhesion was studied in a rabbit deep flexor tendon model. From gross examination, histology, bending angles of joints, tendon gliding excursion and pull-out force, HA-CS-PNIPAM (HACPN) was confirmed to be the best barrier material to prevent post-operative peritendinous adhesion compared to PNIPAM and CS-PNIPAM (CPN) hydrogels and a commercial barrier film Seprafilm®. There was no significant difference in the breaking strength of HACPN-treated tendons and spontaneously healed ones, indicating HACPN hydrogel application did not interfere with normal tendon healing. We conclude that HACPN hydrogel can provide the best functional outcomes to significantly prevent post-operative tendon adhesion in vivo.

STATEMENT OF SIGNIFICANCE

We prepared thermo-responsive in-situ forming hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) to prevent post-operative peritendinous adhesion. The injectable barrier hydrogel could have better anti-adhesive properties than current commercial products by acting as barrier material to block penetration of fibroblasts, providing mobility and flexibility during application and enabling injection through a small opening to fill spaces of any shape after surgery. The effectiveness of preventing post-operative peritendinous adhesion was studied in a rabbit deep flexor tendon model. From gross examination, histology, bending angles of joints, tendon gliding excursion and pull-out force, HA-CS-PNIPAM (HACPN) was confirmed to be the best barrier material to prevent post-operative peritendinous adhesion compared to PNIPAM and CS-PNIPAM (CPN) hydrogels and a commercial barrier film Seprafilm®.

Biceps tenotomy in the presence of a supraspinatus tear alters the adjacent intact tendons and glenoid cartilage

A rotator cuff tear is a common injury in athletes and workers who repeatedly perform overhead movements, and it is not uncommon for this demographic to return to activity shortly after treatment. A biceps tenotomy is often performed in the presence of a rotator cuff tear to help reduce pain and improve joint function. However, the effect of this procedure on the surrounding tissues in the glenohumeral joint is unknown. Therefore, the purpose of this study was to investigate the effect of a biceps tenotomy in the presence of a supraspinatus rotator cuff tear followed by overuse activity on ambulatory function and mechanical and histologic properties of the remaining rotator cuff tendons and glenoid cartilage. 46 rats underwent 4weeks of overuse activity to create a tendinopathic condition, then were randomized into two groups: unilateral detachment of the supraspinatus tendon or detachment of the supraspinatus and long head of the biceps tendons. Ambulatory measurements were performed throughout the 8weeks prior to euthanasia, followed by analysis of the properties of the remaining intact tendons and glenoid cartilage. Results demonstrate that shoulder function was not effected in the biceps tenotomy group. However, the intact tendons and glenoid cartilage showed altered mechanical and histologic properties. This study provides evidence from an animal model that does not support the use of tenotomy in the presence of a supraspinatus tendon rotator cuff tear, and provides a framework for physicians to better prescribe long-term treatment strategies for patients.

Biomechanical Evaluation of Unicortical Stress Risers of the Proximal Humerus Associated With Pectoralis Major Repair

Proximal humerus fracture after pectoralis major tendon repair has been recently reported. Although this complication is rare, it may be possible to decrease such risk using newer techniques for myotenodesis. This study was designed to evaluate various unicortical stress risers created at the proximal humeral metadiaphysis during myotenodesis for repair of pectoralis major ruptures. A simulated pectoralis major myotenodesis was performed using fourth-generation Sawbones (N=30). Using previously described anatomic landmarks for the tendinous insertion, 3 repair techniques were compared: bone trough, tenodesis screws, and suture anchors (N=10 each). Combined compression and torsional load was sequentially increased until failure. Linear and rotational displacement data were collected. The average number of cycles before reaching terminal failure was 383 for the bone trough group, 658 for the tenodesis group, and 832 for the suture anchor group. Both the tenodesis and the suture anchor groups were significantly more resistant to fracture than the bone trough group (P<.001). The suture anchor group was significantly more resistant to fracture than the tenodesis group (P<.001). All test constructs failed in rotational stability, producing spiral fractures, which incorporated the unicortical defects in all cases. When tested under physiologic parameters of axial compression and torsion, failure occurred from rotational force, producing spiral fractures, which incorporated the unicortical stress risers in all cases. The intramedullary suture anchor configuration proved to be the most stable construct under combined axial and torsional loading. Using a bone trough technique for proximal humerus myotenodesis may increase postoperative fracture risk. [Orthopedics. 2017; 40(5):e801-e805.].

Association Between Years of Competition and Shoulder Function in Collegiate Swimmers

BACKGROUND

Shoulder injuries are common among competitive swimmers, and the progression of shoulder pathology is not well understood. The objective of this study was to assess the extent to which years of competitive swim training were associated with physical properties of the supraspinatus muscle and tendon, shoulder strength, and self-reported assessments of shoulder pain and function.

HYPOTHESIS

Increasing years of competition will be associated with declining physical properties of the supraspinatus muscle/tendon and declining self-reported assessments of pain and function.

STUDY DESIGN

Descriptive epidemiology study.

LEVEL OF EVIDENCE

Level 4.

METHODS

After institutional approval, 18 collegiate female swimmers enrolled in the study. For each swimmer, supraspinatus tendon thickness was measured; tendinosis was assessed using ultrasound imaging, supraspinatus muscle shear wave velocity was assessed using shear wave elastography, isometric shoulder strength was measured using a Biodex system, and self-reported assessments of pain/function were assessed using the Western Ontario Rotator Cuff (WORC) score. All subjects were tested before the start of the collegiate swim season. Linear regression was used to assess the association between years of competition and the outcome measures.

RESULTS

Years of participation was positively associated with tendon thickness ( P = 0.01) and negatively associated with shear wave velocity ( P = 0.04) and WORC score ( P < 0.01). Shoulder strength was not associated with years of participation ( P > 0.39).

CONCLUSION

Long-term competitive swim training is associated with declining measures of supraspinatus muscle/tendon properties and self-reported measures of pain and function. Although specific injury mechanisms are still not fully understood, these findings lend additional insight into the development of rotator cuff pathology in swimmers.

CLINICAL RELEVANCE

Lengthy swimming careers may lead to a chronic condition of reduced mechanical properties in the supraspinatus muscle and tendon, thereby increasing the likelihood of rotator cuff pathology.

The Relationships Between Surface Measurements and Underlying Tendon Autograft Length for Upper Extremity Reconstructive Surgery

PURPOSE

The availability of tendon grafts is an important consideration for successful upper extremity reconstructive surgery, including flexor or extensor tendon reconstructions, tendon transfers, and ligament reconstructions. Graft selection is based on availability, expendability, ease of harvest, and length. Given variations in patient height and extremity length, existing average values may provide suboptimal insight into actual tendon lengths available. The purpose of this study is, therefore, to pursue a method of estimating available donor tendon lengths based on easily measured anatomical surface landmarks.

METHODS

Thirty cadaveric upper and lower extremity limbs were dissected and the length of commonly harvested tendon grafts including the palmaris longus, extensor indicis proprius, extensor digiti minimi, plantaris, and second long toe extensor was measured. Surface forearm length (from finger tip to cubital fossa) and surface fibular length (from lateral malleolus to fibular head) were also measured. Correlations between surface measurements and underlying tendon lengths were analyzed, and linear models were generated that predicted tendon length as a function of surface measurements.

RESULTS

Surface measurements were correlated with underlying tendon length (R = 0.46 - 0.66). Linear models could predict tendon lengths based on surface measurements. A ratio of donor tendon length compared with the limb segment measured was established for each tendon and can be applied to estimate donor tendon length. For the upper extremity tendons, the multipliers for the palmaris longus, extensor indicis proprius, and extensor digiti minimi were 0.51, 0.20, and 0.18, respectively. Lower extremity tendon ratios for the plantaris and extensor digitorum longus were 0.69 and 0.60, respectively.

CONCLUSIONS

Although length of available donor tendon can be a limiting variable at the time of surgery, surgeons may be better able to estimate underlying tendon lengths using easily obtained superficial measurements.

CLINICAL RELEVANCE

Information obtained from these cadaveric measurements may aid in preoperative planning in hand and upper extremity surgery.

Investigating mechanisms of tendon damage by measuring multi-scale recovery following tensile loading

Tendon pathology is associated with damage. While tendon damage is likely initiated by mechanical loading, little is known about the specific etiology. Damage is defined as an irreversible change in the microstructure that alters the macroscopic mechanical parameters. In tendon, the link between mechanical loading and microstructural damage, resulting in macroscopic changes, is not fully elucidated. In addition, tendon damage at the macroscale has been proposed to initiate when tendon is loaded beyond a strain threshold, yet the metrics to define the damage threshold are not determined. We conducted multi-scale mechanical testing to investigate the mechanism of tendon damage by simultaneously quantifying macroscale mechanical and microstructural changes. At the microscale, we observe full recovery of the fibril strain and only partial recovery of the interfibrillar sliding, indicating that the damage initiates at the interfibrillar structures. We show that non-recoverable sliding is a mechanism for tendon damage and is responsible for the macroscale decreased linear modulus and elongated toe-region observed at the fascicle-level, and these macroscale properties are appropriate metrics that reflect tendon damage. We concluded that the inflection point of the stress-strain curve represents the damage threshold and, therefore, may be a useful parameter for future studies. Establishing the mechanism of damage at multiple length scales can improve prevention and rehabilitation strategies for tendon pathology.

STATEMENT OF SIGNIFICANCE

Tendon pathology is associated with mechanically induced damage. Damage, as defined in engineering, is an irreversible change in microstructure that alters the macroscopic mechanical properties. Although microstructural damage and changes to macroscale mechanics are likely, this link to microstructural change was not yet established. We conducted multiscale mechanical testing to investigate the mechanism of tendon damage by simultaneously quantifying macroscale mechanical and microstructural changes. We showed that non-recoverable sliding between collagen fibrils is a mechanism for tendon damage. Establishing the mechanism of damage at multiple length scales can improve prevention and rehabilitation strategies for tendon pathology.

Clinical outcomes and frontal plane two-dimensional biomechanics during the 30-second single leg stance test in patients before and after hip abductor tendon reconstructive surgery

BACKGROUND

Hip abductor tendon tears are a common cause of Greater Trochanteric Pain Syndrome. Conservative treatments are often ineffective and surgical reconstruction may be recommended. This study investigated the improvement in clinical outcomes and frontal plane two-dimensional biomechanics during a 30-second single leg stance test, in patients undergoing reconstruction. We hypothesized that clinical scores and pertinent biomechanical variables would significantly improve post-surgery, and these outcomes would be significantly correlated.

METHODS

Twenty-one patients with symptomatic tendon tears underwent reconstruction. Patients were evaluated pre-surgery, and at 6 and 12months post-surgery, using patient-reported outcome measures, assessment of hip abductor strength and six-minute walk capacity. Frontal plane, two-dimensional, biomechanical variables including pelvis-on-femur angle, pelvic drop, trunk lean and lateral pelvic shift, were evaluated throughout a 30-second single leg stance test. ANOVA evaluated outcomes over time, while Pearson's correlations investigated associations between clinical scores, pain, functional and biomechanical outcome variables.

FINDINGS

While clinical and functional measures significantly improved (P<0.05) over time, no significant group differences (P>0.05) were observed in biomechanical variables from pre- to post-surgery. While five patients displayed a positive Trendelenburg sign pre-surgery, only one was positive post-surgery. Clinical outcomes and biomechanical variables during the single leg stance test were not correlated.

INTERPRETATION

Despite improvements in clinical and functional measures over time, biomechanical changes during a weight bearing single leg stance test were not significantly different following tendon repair. Follow up beyond 12months may be required, whereby symptomatic relief may precede functional and biomechanical improvement.

Foot segmental motion and coupling in stage II and III tibialis posterior tendon dysfunction

BACKGROUND

Classification systems developed in the field of posterior tibialis tendon dysfunction omit to include dynamic measurements. Since this may negatively affect the selection of the most appropriate treatment modality, studies on foot kinematics are highly recommended. Previous research characterised the foot kinematics in patients with posterior tibialis tendon dysfunction. However, none of the studies analysed foot segmental motion synchrony during stance phase, nor compared the kinematic behaviour of the foot in presence of different posterior tibialis tendon dysfunction stages. Therefore, we aimed at comparing foot segmental motion and coupling in patients with posterior tibialis tendon dysfunction grade 2 and 3 to those of asymptomatic subjects.

METHODS

Foot segmental motion of 11 patients suffering from posterior tibialis tendon dysfunction stage 2, 4 patients with posterior tibialis tendon dysfunction stage 3 and 15 asymptomatic subjects was objectively quantified with the Rizzoli foot model using an instrumented walkway and a 3D passive motion capture system. Dependent variables were the range of motion occurring at the different inter-segment angles during subphases of stance and swing phase as well as the cross-correlation coefficient between a number of segments.

RESULTS

Significant differences in range of motion were predominantly found during the forefoot push off phase and swing phase. In general, both patient cohorts demonstrated a reduced range of motion compared to the control group. This hypomobility occurred predominantly in the rearfoot and midfoot (p<0.01). Significant differences between both posterior tibialis tendon dysfunction patient cohorts were not revealed. Cross-correlation coefficients highlighted a loss of joint coupling between rearfoot and tibia as well as between rearfoot and forefoot in both posterior tibialis tendon dysfunction groups.

INTERPRETATION

The current evidence reveals considerable mechanical alterations in the foot which should be considered in the decision making process since it may help explaining the success and failure of certain conservative and surgical interventions.

Knee stiffness and viscosity: New implementation and perspectives in prosthesis development

The pendulum test is a method applied to measure passive resistance of the knee. A new and simple pendulum test with instrumentation based on infrared camera was used to evaluate knee stiffness and viscosity on a female human cadaver. The stiffness and viscosity were calculated based on the kinetic data. During the measurements, the periarticular and intraarticular soft tissue of the knee was gradually removed to determine the stiffness and viscosity as a function of the tissue removal rate. The measurements showed that the removal of tissue around the joint reduces the damping of leg oscillation, and therefore decreases the stiffness and viscosity. The contribution to knee joint damping was 10% for the skin, 20% for ligaments, and 40% for muscles and tendons. Tissue removal has a very large impact on the knee stiffness and viscosity.