Flexor tendon injuries are complex, and management of these injuries requires consideration of the surgical timing, injury location, approach, and soft tissue handling. Complications are common, including adhesions, tendon rupture, infection, and a high reoperation rate for zone 2 repairs. Special considerations are given to chronic ruptures, concomitant fractures, and pediatric cases. We discuss current concepts that may improve patient outcomes.

Flexor tendon lacerations are primarily treated by surgical repair. Limited intrinsic healing ability means the repair site can remain weak. Furthermore, adhesion formation may reduce range of motion post-operatively. Mesenchymal stromal cells (MSCs) have been trialled for repair and regeneration of multiple musculoskeletal structures. Our goal was to determine the efficacy of MSCs in enhancing the biomechanical properties of surgically repaired flexor tendons. A PRISMA systematic review was conducted using four databases (PubMed, Ovid, Web of Science, and CINAHL) to identify studies using MSCs to augment surgical repair of flexor tendon injuries in animals compared to surgical repair alone. Nine studies were included, which investigated either bone marrow- or adipose-derived MSCs. Results of biomechanical testing were extracted and meta-analyses were performed regarding the maximum load, friction and properties relating to viscoelastic behaviour. There was no significant difference in maximum load at final follow-up. However, friction, a surrogate measure of adhesions, was significantly reduced following the application of MSCs (p = 0.04). Other properties showed variable results and dissipation of the therapeutic benefits of MSCs over time. In conclusion, MSCs reduce adhesion formation following tendon injury. This may result from their immunomodulatory function, dampening the inflammatory response. However, this may come at the cost of favourable healing which will restore the tendon\'s viscoelastic properties. The short duration of some improvements may reflect MSCs\' limited survival or poor retention. Further investigation is needed to clarify the effect of MSC therapy and optimise its duration of action.

Treating flexor tendon injuries within the digital flexor sheath (commonly referred to as palmar hand zone 2) presents both technical and logistical challenges. Success hinges on striking a delicate balance between safeguarding the surgical repair for tendon healing and initiating early rehabilitation to mitigate the formation of tendon adhesions. Adhesions between tendon slips and between tendons and the flexor sheath impede tendon movement, leading to postoperative stiffness and functional impairment. While current approaches to flexor tendon repair prioritize maximizing tendon strength for early mobilization and adhesion prevention, factors such as pain, swelling, and patient compliance may impede postoperative rehabilitation efforts. Moreover, premature mobilization could risk repair failure, necessitating additional surgical interventions. Pharmacological agents offer a potential avenue for minimizing inflammation and reducing adhesion formation while still promoting normal tendon healing. Although some systemic and local agents have shown promising results in animal studies, their clinical efficacy remains uncertain. Limitations in these studies include the relevance of chosen animal models to human populations and the adequacy of tools and measurement techniques in accurately assessing the impact of adhesions. This article provides an overview of the clinical challenges associated with flexor tendon injuries, discusses current on- and off-label agents aimed at minimizing adhesion formation, and examines investigational models designed to study adhesion reduction after intra-synovial flexor tendon repair. Understanding the clinical problem and experimental models may serve as a catalyst for future research aimed at addressing intra-synovial tendon adhesions following zone 2 flexor tendon repair.

OBJECTIVE: Multiple procedures have been described for wrist and finger flexion contractures and spasticity. Fractional lengthening of forearm flexor tendons involves making parallel transverse tenotomies at the musculotendinous junction to elongate the muscle. Currently, there is limited literature to define the biomechanical consequences of this lengthening technique.
METHODS: Forty-eight flexor tendons were harvested from eight paired upper limbs including flexor carpi radialis, flexor carpi ulnaris, flexor pollicis longus, and flexor digitorum superficialis tendons. Each tendon that was lengthened was paired with the contralateral tendon as a control. A pair of transverse tenotomies were completed for the fractional lengthening. The first tenotomy was performed at the musculotendinous junction where the tendon narrowed to 75% of its maximal width. The second tenotomy was made 1 cm distal to the first. Tendon length was measured before and after fractional lengthening at a constant resting tension of 1 N. The maximum load at failure of each tendon and the mechanism of failure were each measured and compared with the contralateral side.
RESULTS: After fractional lengthening, the mean increase in resting tendon length was 4 mm. When loaded to failure, the mean maximum load of fractionally lengthened tendons was 42% of the mean maximum load of intact tendons. All lengthened tendons failed at the distal tenotomy site.
CONCLUSIONS: Fractional lengthening resulted in an increase of 3-6 mm (mean: 4 mm) in tendon length at resting tension. There was a significant loss in tensile strength and load to failure following fractional lengthening compared with an intact musculotendinous unit.
CONCLUSIONS: The reduction in tensile strength following fractional lengthening results in loads at failure that are, in some cases, lower than the estimated forces required to perform basic tasks. Caution during the healing and rehabilitation period is warranted.

A 29-year-old right-handed woman presented to an outside emergency department with right small finger pain, swelling, and concern for a retained wooden splinter. Diagnosis and treatment were delayed for 2 weeks due to the inability to identify the foreign body clinically or radiographically. Ultimately, ultrasonography by a fellowship-trained specialist was used to localize the wooden splinter. It was embedded within the flexor tendon sheath but had migrated away from its initial point of entry. The patient underwent subsequent surgical extraction, irrigation, and debridement. Two weeks following surgery, she had regained full range of motion through her digit without signs of infection. This case highlights the use of diagnostic ultrasound to identify a radiolucent foreign body, such as a wooden splinter, and to guide subsequent surgical extraction.

Introduction: Flexor tendon laceration is often followed by retraction of the proximal stump. The goals of this review were to describe the myriad of proximal stump retrieval surgical techniques and where available to provide the clinical evidence associated with each. Methods: A Medline and Web of Science search was performed to identify any publication whose primary purpose was to describe a tendon retrieval technique. The techniques were assigned to 8 groups. Clinical outcomes, where reported, and advantages and disadvantages of the technique as reported by the authors of the articles were analyzed. Results: Eight-hundred and forty-one publications complied with the search terms, and 33 articles were included in the current analysis. Only 2 of these articles were randomized controlled trials, and they were of low quality. Conclusion: There is no high-quality evidence to allow quantitative comparison of tendon retrieval techniques. An incremental approach can be recommended based on the qualitative review. After failed atraumatic attempts to retrieve the tendon by milking, retrieval should be done through proximal incision at the A1 pulley level, preferably without pulling the tendon out of the wound. When available, using an endoscope to retrieve the tendon appears to be a promising alternative.
Introduction: Une lacération des tendons fléchisseurs est souvent suivie de la rétraction du moignon proximal. Les buts de cette revue étaient de décrire la myriade de techniques chirurgicales de récupération du moignon proximal et, quand cela était possible, de fournir les données probantes cliniques associées à chaque technique. Méthodes: Une recherche dans les bases de données Medline et Web of Science a été réalisée pour identifier toute publication dont l’objectif principal était de décrire une technique de récupération d’un tendon. Les techniques ont été réparties en huit groupes. Les résultats cliniques, quand ils étaient décrits, et les avantages et inconvénients de chaque technique tels que décrits par les auteurs des articles ont été analysés. Résultats: Huit cent quarante et une publications répondaient aux termes de la recherche et 33 articles ont été inclus dans la présente analyse. Seulement deux de ces articles étaient des essais contrôlés randomisés et ils étaient de mauvaise qualité. Conclusion: Il n’existe pas de données probantes de haute qualité qui permettent une comparaison quantitative entre les techniques de récupération des tendons. Une approche incrémentielle peut être recommandée en se basant sur la revue qualitative. Après des tentatives infructueuses de récupération du tendon par succion, la récupération devrait être faite par incision proximale au niveau de la poulie A1, de préférence sans tirer le tendon hors de la plaie. Quand cela est possible, l’utilisation d’un endoscope pour récupérer le tendon semble être une option prometteuse.

The management of flexor tendon injury has seen many iterations over the years, but more substantial innovations in practice have been sadly lacking. The aim of this study was to investigate the current practice of flexor tendon injury management, and variation in practice from the previous reports, most troublesome complications, and whether there was a clinical interest in potential innovative tendon repair technologies. An online survey was distributed via the British Society for Surgery of the Hand (BSSH) and a total of 132 responses were collected anonymously. Results showed that although most surgeons followed the current medical recommendation based on the literature, a significant number of surgeons still employed more conventional treatments in clinic, such as general anesthesia, ineffective tendon retrieval techniques, and passive rehabilitation. Complications including adhesion formation and re-rupture remained persistent. The interest in new approaches such as use of minimally invasive instruments, biodegradable materials and additive manufactured devices was not strong, however the surgeons were potentially open to more effective and economic solutions.

UNASSIGNED: Bizarre Parosteal Osteochondromatous Proliferation (BPOP) is a rare benign lesion commonly referred to as Nora\'s lesion. It typically affects adults in their 20s-30s. Due to its aggressive local invasion, it can be confused with some malignant tumors, including chondrosarcoma. Nora\'s lesion can be diagnosed radiographically, and its diagnosis is confirmed with an excisional biopsy.
UNASSIGNED: A 40-year-old Bahraini male complained of swelling over the metatarsal head of the second digit, increasing in size over a year. He also complained of a reduced range of motion of the second toe and a pins-and-needles sensation affecting the entire toe. Plain X-ray, computed tomography, and magnetic resonance imaging were done, showing findings suggestive of bizarre parosteal osteochondromatous. The lesion was encasing the flexor tendon of the second digit. He was treated with surgical excision, and histopathology confirmed the diagnosis of BPOP.
UNASSIGNED: We report on a rare presentation of BPOP in the second proximal phalanx of a male in his 40 s. The patient underwent a wide local excision, and the diagnosis was confirmed with histopathology.

The flexor tendon pulleys in the fingers of the hand are fibrous structures of variable size, shape, and thickness that cover the synovial sheath of these tendons. Despite their clinical relevance, their arrangement and configuration in each of the triphalangeal fingers have been little studied and with small sample sizes. 192 triphalangeal fingers belonging to 48 fresh body donors\' hands were dissected. Multivariate analysis was carried out. Twenty-five cases (52%) were left hands, and 26 of the 48 hands belonged to female donors (54.2%). The results were analyzed by fingers for each of the 5 annular pulleys, the 3 cruciform pulleys and the gaps between them. In addition, the most and least frequent configurations of the pulleys in each of the fingers were studied, observing that the classic pattern with all the pulleys appeared only in 3 fingers (1.56%), while the most frequent pattern was A1-A2-C1-A3-A4, which was seen in 35 fingers (18.22%). CONCLUSIONS: The flexor pulleys in the triphalangeal fingers of the hand have shown enormous variability in arrangement and shape, and also rarely appear all in the same finger. This peculiar anatomical arrangement can help the different professionals who perform their clinical work in this region.

The enthesis, the specialized junction between tendon and bone, is a common site of injury. Although notoriously difficult to repair, advances in interfacial tissue engineering techniques are being developed for restorative function. Most notably are 3D in vitro co-culture models, built to recreate the complex heterogeneity of the native enthesis. While cell and matrix properties are often considered, there has been little attention given to native enthesis anatomical morphometrics and replicating these to enhance clinical relevance. This study focuses on the flexor digitorum profundus (FDP) tendon enthesis and, by combining anatomical morphometrics with computer-aided design, demonstrates the design and construction of an accurate and scalable model of the FDP enthesis. Bespoke 3D-printed mould inserts were fabricated based on the size, shape and insertion angle of the FDP enthesis. Then, silicone culture moulds were created, enabling the production of bespoke anatomical culture zones for an in vitro FDP enthesis model. The validity of the model has been confirmed using brushite cement scaffolds seeded with osteoblasts (bone) and fibrin hydrogel scaffolds seeded with fibroblasts (tendon) in individual studies with cells from either human or rat origin. This novel approach allows a bespoke anatomical design for enthesis repair and should be applied to future studies in this area.