Gene-Loaded Nanoparticle-Coated Sutures Provide Effective Gene Delivery to Enhance Tendon Healing.

How to accelerate tendon healing remains a clinical challenge. In this study, a suture carrying nanoparticle/pEGFP-basic fibroblast growth factor (bFGF) and pEGFP-vascular endothelial growth factor A (VEGFA) complexes was developed to transfer the growth factor genes into injured tendon tissues to promote healing. Polydopamine-modified sutures can uniformly and tightly absorb nanoparticle/plasmid complexes. After tendon tissues were sutured, the nanoparticle/plasmid complexes still existed on the suture surface. Further, we found that the nanoparticle/plasmid complexes delivered into tendon tissues could diffuse from sutures to tendon tissues and effectively transfect genes into tendon cells, significantly increasing the expression of growth factors in tendon tissues. Finally, biomechanical tests showed that nanoparticle/pEGFP-bFGF and pEGFP-VEGFA complex-coated sutures could significantly increase the ultimate strengths of repaired tendons, especially at 4 weeks after operation. Two kinds of nanoparticle/plasmid complex-coated sutures significantly increased flexor tendon healing strength by 3.7 times for Ethilon and 5.8 times for PDS II, respectively, compared with the corresponding unmodified sutures. In the flexor tendon injury model, at 6 weeks after surgery, compared with the control suture, the nanoparticle/plasmid complex-coated sutures can significantly increase the gliding excursions of the tendon and inhibit the formation of adhesion. These results indicate that this nanoparticle/plasmid complex-coated suture is a promising tool for the treatment of injured tendons.

Length Changes in Scapholunate Interosseous Ligament With Resisted Wrist Radial and Ulnar Inclination.

PURPOSE: To investigate the changes in length of the scapholunate interosseous ligament (SLIL) when the wrist is resisting horizontal lateral load and the forearm is in full pronation in vivo. METHODS: We obtained computed tomography scans of the wrists of 6 volunteers in 3 situations: 0° position (0° extension and 0° ulnar inclination) and full forearm pronation without force, and in the same position but with resisted ulnar and radial deviation. Nine zones of 3 subregions of the SLIL were measured and analyzed with computer modeling. RESULTS: Changes in length of the palmar SLIL with resisted ulnar deviation were significantly greater than those without an applied lateral load. In contrast, the changes in length of the dorsal SLIL with resisted radial deviation were statistically greater than those in the 0° position without loading. However, no significant differences in the changes in length of the proximal SLIL were found in any of 3 situations, except the dorsal zone with resisted radial deviation. CONCLUSIONS: Application of lateral load has an effect on the separation of the palmar and dorsal insertions of the SLIL. The palmar subregion of the SLIL was more highly strained with wrist-resisted ulnar deviation. Conversely, the dorsal subregion of the SLIL was under greater tension with wrist-resisted radial deviation. CLINICAL RELEVANCE: For patients undergoing nonsurgical treatment of SLIL tears, a sudden contraction of ulnar or radial deviation agonist muscles may be harmful and contribute to SL instability.

History and Nomenclature of Multistrand Repairs in Digital Flexor Tendons.

Multistrand core suture repairs have become the mainstay of digital flexor tendon repair in recent decades. Here we briefly describe the history of the development of these multistrand repair methods and their correct nomenclature. A historical account, their evolution, the correct use of nomenclature, and some technical points are reviewed.

Effective modulation of transforming growth factor-ß1 expression through engineered microRNA-based plasmid-loaded nanospheres.

BACKGROUND AIMS: Sustained gene delivery could be particularly necessary in modulating gene expression in healing intrasynovial tendons and may be a promising approach for preventing adhesions. METHODS: Polylactic-co-glycolic acid nanospheres were prepared and were then incorporated with plasmids expressing enhanced green fluorescence protein and miRNA for inhibiting the transforming growth factor-ß1 gene expression. RESULTS: We demonstrated that cultured tenocytes could be effectively transfected by means of nanosphere/plasmid. The expression of transforming growth factor-ß1 is significantly downregulated in healing chicken flexor tendon treated with nanosphere/plasmid. Histology analysis did not demonstrate any significant inflammation or necrosis in tendons injected with nanosphere/plasmid after surgery. CONCLUSIONS: Nanosphere/plasmid may be a promising non-viral vector for gene therapy of the injured flexor tendon.

In Vivo Contact Characteristics of Distal Radioulnar Joint With Malunited Distal Radius During Wrist Motion.

PURPOSE: To determine whether distal radioulnar joint (DRUJ) contact characteristics were altered in patients with malunited distal radius fractures. METHODS: We obtained computed tomography scans at 5 positions of both wrists of 6 patients who had unilateral malunited distal radius fractures with dorsal angulation from 10° to 20° and ulnar variance less than 3 mm. We reconstructed 3-dimensional images and mapped contact regions of DRUJ by calculating the shortest distance between the 2 opposing bones. The contact areas of the DRUJ were measured and the contact region centers were calculated and analyzed. The values of the malunited side were compared with those of the contralateral uninjured side. RESULTS: In the uninjured wrist, the contact areas of the DRUJ increased slightly from wrist flexion to extension and ulnar deviation. In the malunited wrist, we found the contact areas of DRUJ to be progressively reduced from 20° flexion to neutral, 40° extension, and 20° extension, to ulnar deviation. The centroid of this area on the sigmoid notch moved to distal from flexion to extension. Compared with the contralateral uninjured wrist, the contact area significantly decreased during wrist extension and ulnar deviation, and significantly increased during wrist flexion. The centroids of this area on sigmoid notch all moved volarly in all selected wrist positions. CONCLUSIONS: The contact areas of the DRUJ and the centroid of contact area on sigmoid notch are altered in patients with malunited distal radius fractures. The contact area of the DRUJ increases during wrist flexion and decreases during wrist extension and ulnar deviation. The centroids of the contact area on sigmoid notch move volarly during wrist flexion-extension and ulnar deviation. CLINICAL RELEVANCE: The in vivo findings suggest that alterations in joint mechanics may have an important role in the dysfunction associated with these injuries.

Length changes of scapholunate interosseous ligament at different wrist positions: an in vivo 3-dimension image study.

PURPOSE: The scapholunate interossous ligament (SLIL) has a critical role in maintaining the proper kinematic relationship between the scaphoid and the lunate. We hypothesize that the length of SLIL changes significantly at wrist full extension and during forearm rotation. The aim of this study was to investigate the length changes of SLIL at wrist full extension and forearm rotation in vivo. METHODS: Twelve volunteers were randomly divided to two groups. We obtained computed tomography scans of the wrists at different wrist positions. The three regions of the SLIL were measured and analyzed with computer modeling. RESULTS: The results showed that from the neutral to full extension of the wrist, the length of volar SLIL and volar, middle portions of the proximal SLIL increased significantly. The volar and proximal SLIL increased significantly in maximal forearm pronation. CONCLUSIONS: The lengths of the volar and proximal regions of SLIL increase substantially at wrist full extension, but only slightly at maximal forearm pronation. Clinically, wrist full extension may make the SLIL ligament vulnerable to disruption.

Regulatory effects of introduction of an exogenous FGF2 gene on other growth factor genes in a healing tendon.

In this study of a tendon injury model, we investigated how injection of a vector incorporating one growth factor gene changes expression levels of multiple growth factor genes in the healing process. The flexor tendon of chicken toes was completely cut and repaired surgically. The tendons in the experimental arm were injected with an adeno-associated virus-2 vector incorporating basic fibroblast growth-factor gene, whereas the tendons in the control arm were not injected or injected with sham vectors. Using real-time polymerase chain reaction, we found that, within the tendon healing period, a set of growth factor genes-transforming growth factor-ß1, vascular endothelial growth factor, and connective tissue growth factor-were significantly up-regulated. Expression of the platelet-derived growth factor-B gene was not changed, and the insulin-like growth factor was down-regulated. A tendon marker gene, scleraxis, was significantly up-regulated in the period. Our study revealed an intriguing finding that introduction of one growth factor gene in the healing tendon modulated expression of multiple growth factor genes. We believe this study may have significant implications in determining the approach of gene therapy, and the findings substantiate that gene therapy using a single growth factor could affect multiple growth factors.

Release of the A4 pulley to facilitate zone II flexor tendon repair.

During primary or delayed primary repair of the flexor digitorum profundus tendon, surgeons often face difficulty in passing the retracted tendon or repaired tendon under the dense, fibrous A4 pulley. The A4 pulley is the narrowest part of the flexor sheath, proximal to the terminal tendon. Disrupted tendon ends (or surgically repaired tendons) are usually swelling, making passage of the tendons under this pulley difficult or even impossible. During tendon repair in the A4 pulley area, when the trauma is in the middle part of the middle phalanx and the A3 pulley is intact, the A4 pulley can be vented entirely to accommodate surgical repair and facilitate gliding of the repaired tendon after surgery. Venting the pulley does not disturb tendon function when the other major pulleys are intact and when the venting of the A4 pulley and adjacent sheath is limited to the middle half of the middle phalanx. Such venting is easily achieved through a palmar midline or lateral incision of the A4 pulley and its adjacent distal or/and proximal sheath, which helps ensure a more predictable recovery of digital flexion and extension.

The effect of asymmetric core suture purchase on gap resistance of tendon repair in linear cyclic loading.

PURPOSE: To evaluate the biomechanical properties of an asymmetric core suture for tendon repair. METHODS: Sixty porcine flexor tendons were repaired with 3 different 4-strand sutures using different core suture purchases: 2 sets of identical purchases of 10 mm, 2 sets of asymmetric purchases (8 mm proximal/distal stump and 12 mm distal/proximal stump), and 2 sets of identical purchases of 12 mm. The tendons were subjected to the cyclic loading for 20 cycles. The number of tendons with gaps at each cycle, elongation of gap area between tendon ends and tendon segment, gap formation forces, and ultimate strengths were recorded. RESULTS: Tendons repaired with the asymmetric core suture purchases had the smallest gaps during cyclic loading. The elongation of gaps and tendon segments were significantly smaller than those with symmetric suture purchase of 10 or 12 mm. The asymmetric core suture repair had significant higher gap resistance forces than the symmetric suture repair at the final loading cycle. CONCLUSIONS: A 4-strand core suture repair with asymmetric purchases on the tendon stumps generated greater gapping resistance than that with an equal length of suture purchase. CLINICAL RELEVANCE: The asymmetric core suture purchase may be a practical measure to improve gapping resistance and fatigue strength when the suture purchase meets essential length requirements.

Complications of flexor tendon repair.

This article reviews and highlights complications of flexor tendon repairs. Although the outcomes of flexor tendon repairs have improved over the years, fair or poor functional outcomes are seen, especially in patients whose trauma involves multiple structures of the hand and in zone 5 with multiple tendon lacerations. Rupture of the flexor tendon after repair is no longer a major problem if current repair principles are carefully adhered to. Different degrees of adhesion formations and interphalangeal (IP) joint stiffness still occur in a few patients. Early active postoperative mobilization and use of a shorter splint with sparing of the wrist are effective measures to prevent adhesion formation and IP joint stiffness. Given the overall poor results and high rate of complications with flexor digitorum profundus (FDP) repairs in zone 1, a direct repair of the FDP tendon to any short remnant of the distal insertion with 10-strand or even stronger core suture repair is adopted by many units.

Diagnostic and treatment recommendations for recurrent or persistent symptoms after trapeziectomy: a Delphi study.

The aim of this Delphi study was to provide a diagnostic and treatment algorithm for patients with persistent or recurrent symptoms after trapeziometacarpal joint resection arthroplasty. Three Delphi rounds were conducted in which surveys were sent to 182 experienced hand surgeons worldwide. Responses were received from 140 participants. A consensus threshold was set at 67% agreement. Diagnostic tools and treatment approaches for six common revision scenarios achieved consensus. Radiographs are appropriate as primary (97%) and CT scans as secondary (76%) diagnostic tools. For scaphometacarpal impingement, 67% of respondents agreed that revision interposition is appropriate, with 93% recommending autologous tendon for the interposition. Additional suspension was considered appropriate by 68% of the participants. The diagnostic and treatment algorithm can help the surgeon to identify the reason for persistent symptoms after trapeziometacarpal joint resection arthroplasty and to choose an appropriate treatment strategy.Level of evidence: V.

Changes in contact site of the radiocarpal joint and lengths of the carpal ligaments in forearm rotation: an in vivo study.

PURPOSE: To examine the contact site of the radiocarpal joint and lengths of carpal ligaments at different forearm rotations in vivo. Rotation of the forearm could exert noteworthy influence on mechanics of the wrist, and understanding how forearm rotation influences wrist mechanics may help treat carpal disorders because wrist position closely relates to forearm rotation. METHODS: We obtained computed tomography scans of the wrists of 8 volunteers at the following 7 positions of forearm rotation: neutral; 30°, 60°, and 90° of pronation; and 30°, 60°, and 90° of supination. Three-dimensional images of the carpals and distal radius and ulna were reconstructed with software. Subsequently, the contact site of the scaphoid and lunate on the radial articular surface and the lengths of 8 carpal ligaments between their respective origin and insertion points were measured and compared among different positions of forearm rotation. RESULTS: We found that the contact site of the scaphoid on the distal radius moved between 0.2 and 2.0 mm during forearm rotation. The lengths of the 3 ulnar carpal ligaments (ie, ulnocapitate [UC], ulnolunate [UL], and ulnotriquetral [UT] ligaments) showed the greatest and significant change. From neutral position to pronation, the UC, UL, and UT ligaments shortened significantly. From neutral position to supination, the UT ligament lengthened significantly, but the radioscaphocapitate, UC, UL, and dorsal intercarpal ligaments decreased significantly. CONCLUSIONS: During forearm rotation, the contact site of the scaphoid and the lunate on the distal radial articular surface changed minimally. The lengths of 3 ulnar carpal ligaments (UC, UL, and UT ligaments) changed substantially. CLINICAL RELEVANCE: Our findings will help elucidate carpal biomechanics during forearm rotation. The findings may inform decisions about how to reduce the load to these carpal ligaments when treating the carpal disorders.

Apoptosis in adhesions and the adhesion-tendon gliding interface: relationship to adhesion-tendon gliding mechanics.

PURPOSE: Adhesion formation is closely related to tendon-gliding function. We aimed to investigate apoptosis (programmed cell death) in adhesions and tendons and study its relationship to the mechanics of adhesions and healing tendons. METHODS: The flexor digitorum profundus tendons of 30 long toes in 15 chickens were completely transected and repaired surgically. At postoperative weeks 4, 6, and 8, tendon-gliding excursions were tested and adhesion scores were recorded. Tendons and surrounding adhesions were then harvested for analysis of apoptosis using in situ terminal deoxynucleotidyl transferase dUTP (deoxyuridine triphosphate) nick end labeling assay. Three-dimensional image reconstruction was used to provide an overall view of cellular distribution in tendons and adhesions. Finally, we analyzed the correlation between the apoptotic index measured at the adhesions and the gliding excursions. Ten uninjured tendons served as normal controls. RESULTS: Apoptosis was found to be a dominant cellular event in the adhesion tissues at both the adhesion-tendon gliding interface and the adhesion core. The apoptotic index in the adhesions was generally above 20% to 50%. The apoptotic index was significantly higher in the adhesions than in the junction region of the cut tendon ends at weeks 4, 6, and 8. A higher apoptotic index in the adhesions significantly correlated to lower tendon excursions at week 6. CONCLUSIONS: Apoptosis in adhesions and at the adhesion-tendon interface is a prominent event in the tendon-healing process. The tendons exhibiting a lower tendon-gliding amplitude, meaning more severe adhesions, tended to have a greater apoptotic index in their adhesions during a certain period of the tendon-remodeling process. CLINICAL RELEVANCE: Apoptosis in the adhesions and at the adhesion-tendon interface may contribute remarkably to the fate of adhesions and the restoration of the tendon gliding surface, which may be closely related to the tendon function.

In vivo gliding and contact characteristics of the sigmoid notch and the ulna in forearm rotation.

PURPOSE: To investigate shifting of the contact center over the surfaces of 2 opposing bones of the distal radioulnar joint during forearm rotation. METHODS: We recruited 8 volunteers and used their right wrists. Serial computed tomography scans were obtained with the forearm at neutral position and 6 other positions of forearm rotation. We reconstructed 3-dimensional images and mapped contact regions of both the sigmoid notch and ulnar head by calculating the shortest distance between the 2 opposing bones. The center of contact was also defined and plotted against the distal radioulnar joint rotation to determine the sliding distance over the surfaces of the 2 bones. RESULTS: During forearm rotation, the maximal sliding of the sigmoid notch over the ulnar head was 7.4 mm in forearm pronation and 9.2 mm in forearm supination, which occurred in volar-dorsal direction primarily. Sliding of the ulnar head over the sigmoid notch was more limited, measuring 4.7 mm during pronation and 2.3 mm during supination. Most of the motion occurred between 30° pronation and 60° supination. In the proximal-distal direction, the contact site of the sigmoid notch with the ulnar head translated distally 1.6 mm during pronation and proximally 0.7 mm during supination. CONCLUSIONS: During forearm rotation, the sigmoid notch slides substantially against the ulnar head at each part of the forearm rotation arc. The sliding of the ulnar head over the sigmoid notch is smaller, most of which is at the range from moderate forearm pronation to slight supination. The contact site of the sigmoid notch with the ulnar head moves slightly distally during forearm pronation and proximally during supination. CLINICAL RELEVANCE: The in vivo findings provide more detailed information and insight into distal radioulnar joint motion kinematics.

What to Retain and What to Change in Asian Hand Surgery.

Notice of Editorial Error - Tang JB. What to Retain and What to Change in Asian Hand Surgery. J Hand Surg Asian Pac Vol. 2023 May 5. doi: 10.1142/S2424835523300013. The Journal of Hand Surgery Asian-Pacific Volume (JHS-AP) has rescinded the above paper from journal's website. An edited version of this article has been previously published in the February 2023 issue (Tang JB. Towards Better Hand Surgery. J Hand Surg Asian Pac Vol. 2023 Feb;28(1):1-4. doi: 10.1142/S2424835523400015). It was accidentally given a new DOI number in the article production process due to an editorial error. The online version of the above paper (Tang JB. What to Retain and What to Change in Asian Hand Surgery. J Hand Surg Asian Pac Vol. 2023 May 5. doi: 10.1142/S2424835523300013) has been removed from the JHS-AP webpage and all hosting service providers have been informed of this move. The editors apologise for this error.

Healing strength of tendon repair with or without knots between two tendon ends and histological changes in a chicken model.

We studied the healing strength and histological changes of digital flexor tendons repaired using Kessler (core suture knots placed over the tendon surface) and modified Kessler (core suture knots placed between two tendon ends) in 31 long toes of chicken. Four weeks after surgery, the healing tendons were measured in a tensile testing machine, and the adhesion formation and histological changes were observed. The strength of the Kessler repairs was significantly greater than that of the modified Kessler repairs with a 35% mean difference. No significant difference was found between the adhesion scores of the tendons repaired with both techniques. In histological sections, the arrangement of collagen fibers in the modified Kessler repair group was more disordered. We conclude that the tendons repaired with the Kessler method are stronger than those with the modified Kessler technique. The knots between tendon ends are detrimental to the early healing strength of digital flexor tendons.

Debris flow characteristics of the compound channels with vegetated floodplains.

Compound cross-sections with vegetated floodplains are a common type of cross-section in debris-flow gullies. Floodplain vegetation participates in large-scale debris flow events and regulates debris-flow discharge. Extensive research has been conducted on the water flow characteristics of compound rivers. However, few studies have investigated the debris flow characteristics of compound channels in mountainous areas, particularly those of debris flow and flash flood inundation areas with vegetation. This study discusses the section characteristics of debris flow gullies with vegetated floodplains, gully evolution processes, and their influence on debris flow. The results show that the compound debris flow gully with a vegetated floodplain is formed in the gully from the mature stage to the old-mature stage. The compound sections are developed in flow areas with a gentle slope, which can be bilateral floodplain, unilateral floodplain, and multi-main gully floodplain types. Owing to the vegetation of the floodplain, the roughness of the channel increases, which makes the beach roughness coefficient much larger than that for the main channel. In the integrated Manning coefficient method, the error in resolving the flow velocity and discharge is large and cannot reflect the difference in velocities of the floodplain and main channel, therefore the sectional splitting method is most applicable. Influencing debris flow movement, limiting channel migration, and retaining debris flow to the main channel were the main contributions of the riparian forest zone.

Flexor Tendon Repair Techniques: M-Tang Repair.

The authors present the methods and outcomes from six institutes where M-Tang repairs with early active flexion exercise are used for zone 2 digital flexor tendon repair. The authors had close to zero repair ruptures, and few digits needed tenolysis. The excellent to good results are generally between 80% and 90%. In the pandemic period, less stringent therapy supervision might have allowed some patients to move too aggressively, with repair ruptures not seen before the pandemic in one institute. In Nantong, Yixing, and Saint John, the rupture incidence is zero to 1%. In Florence and Heidelberg, the rupture incidence was 3%.

Effects of tension across the tendon repair site on tendon gap and ultimate strength.

PURPOSE: Tendons repaired with varying amounts of tension result in different degrees of shortening of the tendon segment within core sutures, which may affect tensile strengths. We aimed to investigate the effects of tension across the repair site on gap formation forces and ultimate strength. METHODS: Fifty-seven porcine flexor tendons were repaired with a 2-strand modified Kessler repair or a 4-strand cross-lock repair. For each type of repair, the tendons were divided into 3 groups: by 0%, 10%, or 20% shortening of tendon segment encompassed within core sutures. The repaired tendons had a single load-to-failure test in a materials testing machine. The forces required for initial and 2-mm gap formation and ultimate failure were recorded and statistically compared for each group. RESULTS: With either 2-strand or 4-strand repair, the tendons in the 10% tendon-segment shortening group withstood significantly higher initial and 2-mm gap formation forces than those in the group with no shortening, with average increases of 5 to 10 N after 10% shortening. Increasing the tendon-segment shortening to 20% produced a slight increase in the initial and 2-mm gap forces compared with those with 10% shortening, which was statistically significant only in the tendons with the 4-strand repair. The ultimate strengths were not significantly different among the tendons with either 2-strand or 4-strand repair of any degrees of shortening. CONCLUSIONS: Tensioning the core suture to shorten its encompassed tendon segment by 10% substantially increases resistance to postoperative gapping. Further tensioning to produce 20% shortening of the tendon segment increased the gapping forces by a much smaller amount. This study suggests that a slightly tensioned surgical repair, shortening the encompassed tendon segment by approximately 10%, is appropriate. CLINICAL RELEVANCE: Slightly tensioning core sutures across the tendon repair site, such as adding tension to cause 10% tendon-segment shortening, would greatly increase the gap resistance of the surgical repair.