Clinical outcomes associated with flexor tendon repair

Peritendinous adhesion: Therapeutic targets and progress of drug therapy

Peritendinous adhesion (PA) is one of the most common complications following hand surgery and characterized with abnormal hyperplasia of connective tissue and excessive deposition of extracellular matrix. Subsequently, various clinical symptoms such as chronic pain, limb dyskinesia and even joint stiffness occur and patients are always involved in the vicious cycle of "adhesion - release - re-adhesion", which seriously compromise the quality of life. Until present, the underlying mechanism remains controversial and lack of specific treatment, with symptomatic treatment being the only option to relieve symptoms, but not contributing no more to the fundamentally rehabilitation of basic structure and function. Recently, novel strategies have been proposed to inhibit the formation of adhesion tissues including implantation of anti-adhesion barriers, anti-inflammation, restraint of myofibroblast transformation and regulation of collagen overproduction. Furthermore, gene therapy has also been considered as a promising anti-adhesion treatment. In this review, we provide an overview of anti-adhesion targets and relevant drugs to summarize the potential pharmacological roles and present subsequent challenges and prospects of anti-adhesion drugs.

Intrathecal enalapril reduces adhesion formation in experimentally induced digital flexor tendon sheath injuries in horses

OBJECTIVE

The objectives of the study were to describe a standing percutaneous adhesion induction model in the digital flexor tendon sheath (DFTS) of horses and to evaluate the effect of intrathecal administration of the angiotensin-converting enzyme (ACE) inhibitor enalapril on tendon healing and adhesion formation.

STUDY DESIGN

Randomized, blinded, controlled experimental study.

ANIMALS

Eight healthy horses.

METHODS

A collagenase-induced adhesion model was implemented in the deep digital flexor tendon (DDFT) of both forelimbs under standing ultrasonographic guidance. Daily intrathecal injections of 5 mg enalapril (the treatment condition) were administered to a randomly assigned forelimb for 5 days, with the contralateral limb receiving an equivalent volume of 0.9% NaCl (the control). Lameness and limb circumference were recorded weekly. Horses were euthanized after 8 weeks and evaluated for gross digital flexor tendon sheath (DFTS) adhesions. Tendons were collected for histopathologic scoring of DDFT healing. Paired data were analyzed using a one-sided alternative sign test and longitudinal regression.

RESULTS

Multiple DFTS adhesions were formed in control limbs of all horses. The median number of gross DFTS adhesions in treated limbs was less than in control limbs (p = .0039). The average reduction in limb circumference and lameness scores over time occurred faster in treated versus control limbs (p < .025). There were no differences in DDFT histopathologic scores between groups.

CONCLUSION

The standing percutaneous DFTS adhesion induction model demonstrated that intrathecal enalapril reduced DFTS adhesion formation, lameness scores, and limb circumference over time.

CLINICAL SIGNIFICANCE

Intrathecal enalapril administration may reduce morbidity in horses with naturally occurring tendon injuries.

Current trends in the prevention of adhesions after zone 2 flexor tendon repair

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.

Hyaluronic acid/PEO electrospun tube reduces tendon adhesion to levels comparable to native tendons - An in vitro and in vivo study

A major problem after tendon injury is adhesion formation to the surrounding tissue leading to a limited range of motion. A viable strategy to reduce adhesion extent is the use of physical barriers that limit the contact between the tendon and the adjacent tissue. The purpose of this study was to fabricate an electrospun bilayered tube of hyaluronic acid/polyethylene oxide (HA/PEO) and biodegradable DegraPol® (DP) to improve the anti-adhesive effect of the implant in a rabbit Achilles tendon full laceration model compared to a pure DP tube. Additionally, the attachment of rabbit tenocytes on pure DP and HA/PEO containing scaffolds was tested and Scanning Electron Microscopy, Fourier-transform Infrared Spectroscopy, Differential Scanning Calorimetry, Water Contact Angle measurements, and testing of mechanical properties were used to characterize the scaffolds. In vivo assessment after three weeks showed that the implant containing a second HA/PEO layer significantly reduced adhesion extent reaching levels comparable to native tendons, compared with a pure DP implant that reduced adhesion formation only by 20 %. Tenocytes were able to attach to and migrate into every scaffold, but cell number was reduced over two weeks. Implants containing HA/PEO showed better mechanical properties than pure DP tubes and with the ability to entirely reduce adhesion extent makes this implant a promising candidate for clinical application in tendon repair.

The Evaluation of a Flexor Digitorum Profundus-to-Volar Plate Zone I Repair Versus Button Repair: An In Vitro Biomechanics Study

PURPOSE

The purpose of the study was to evaluate joint kinematics and tendon work of flexion (WOF) following a flexor digitorum profundus (FDP)-to-volar plate (VP) repair technique relative to a pullout button for zone I flexor tendon injuries.

METHODS

Fourteen digits were tested using an in vitro active finger motion simulator under 3 repaired conditions following a simulated zone I avulsion: button, FDP-VP, and "no slack" FDP-VP (corrected for additional VP length). Outcome metrics included active joint range of motion (ROM), fingertip strength, FDP and flexor digitorum superficialis tensile loads, and WOF.

RESULTS

The button and FDP-VP techniques restored WOF to the intact condition for FDP and flexor digitorum superficialis. All repairs restored distal interphalangeal joint ROM and kinematics to the intact condition. Similarly, all repairs restored WOF; however, the "no slack" FDP-VP significantly increased WOF by 10% to 12% over the simple FDP-VP repair. The button technique had similar fingertip strength to the intact condition, whereas the FDP-VP repairs significantly reduced peak fingertip strength from intact, albeit only 1-2 N compared with the button repair.

CONCLUSION

In this in vitro cadaveric model, the button and FDP-VP techniques restored WOF and ROM to within intact levels, with no difference between these repairs in all measured outcome metrics.

CLINICAL RELEVANCE

Based on its initial strength and its equal biomechanical performance compared with the button repair, the FDP-VP technique may be a viable option for treating FDP avulsions.

Revision of Flexor Tendon Repair: Factors Associated With Flexor Tenolysis

BACKGROUND

Tenolysis restores mobility to the flexor tendon through the lysis of adhesions that inhibit and negatively impact functional outcomes following flexor tendon repair. Despite extensive literature on operative techniques and therapy protocols used to minimize adhesion formation, there are limited data examining the association of patient, injury, and postoperative factors with tenolysis. This study aims to: (1) quantify tenolysis rates following flexor tendon repair or reconstruction; and (2) identify patient demographic factors, medical comorbidities, injury characteristics, postoperative diagnoses, and complications associated with tenolysis.

METHODS

PearlDiver was used to identify patients who underwent a flexor tendon repair or reconstruction from 2010 to 2020. Patients were stratified by whether or not flexor tenolysis was performed. Patient demographics, comorbidities, injury characteristics, postoperative diagnoses, and complications were recorded. Logistic regression analysis was used to identify independent risk factors associated with tenolysis.

RESULTS

Database review identified 10 264 patients who underwent either flexor tendon repair or reconstruction, with 612 patients (6.0%) subsequently undergoing tenolysis. Logistic regression analysis determined that vascular injury preceding flexor tendon repair, surgical wound disruption, nerve injury diagnosed postoperatively, postoperative tendon rupture, and need for repeat flexor tendon repair were associated with an increased odds of tenolysis. Patient age, sex, and comorbidities were not associated with performance of tenolysis.

CONCLUSIONS

Although tenolysis rates may differ according to physician and patient preferences, identification of factors associated with tenolysis following flexor tendon repair allows surgeons to risk-stratify patients prior to surgery and help guide postoperative expectations if complications arise.

Comparison of Treatment Outcomes of Different Immobilized Finger Positions After Repair of Flexor Tendon Rupture in Zones I and II: A Nonrandomized Controlled Trial With Historical Control Group

Introduction The position of finger immobilization after flexor tendon rupture repair is changed to the extended position to prevent flexion contracture of the interphalangeal (IP) joint. However, in Strickland's assessment, We believe that a reduction in TAF (total active flexion) affects the outcome and that extension fixation is not necessarily the primary focus. For example, there are management methods that swap the fixed position between day and night. It is assumed that some effect is sought by placing the fingers in the flexed position. That is, the method of fixation is currently selected at individual facilities through twists and turns; however, the indications and criteria for selecting finger fixation positions are ambiguous, and they are apparently subject to the experience of therapists. This study aimed to characterize follow-up outcomes of flexion and extension fixation after zones I and II flexor tendon rupture repair. Methods This nonrandomized controlled trial with historical controls included 25 patients with flexor tendon ruptures of 30 fingers. The flexion fixation group consisted of 12 patients (n=16 fingers) and the extension fixation group consisted of 13 patients (n=14 fingers). The group with flexion fixation comprised patients who slept with their injured fingers in the flexed position (intervention group). The group with extension was retrospectively selected between April 2017 and March 2019, who slept with their injured finger in the extended position (historical control group). Strickland assessments of the range of motion (ROM) of each joint at the conclusion of hand therapy, the ratio of total active motion of the repaired, to the healthy finger (%TAF), and IP joint extension limitation angles were compared using Mann-Whitney U tests. Ratios of excellent and good ratings based on the Strickland assessment were compared using Fisher exact tests. Result The results of the Strickland assessment showed excellent or good outcomes for 22 (73%) of 30 fingers, which was in line with our previous findings. Strickland ratings of excellent were achieved in seven (44%) of 16 fingers and four (28%) of 14 fingers in the groups with flexion and extension fixation, respectively. The outcomes for two (22%) of 16 fingers and seven (78%) of 14 fingers in the groups with flexion and extension fixation were, respectively, rated as good. The proportion of patients rated as excellent was significantly higher in the group with flexion than extension fixation (p=0.040). The %TAF and the active flexion angle of the distal interphalangeal (DIP) joint were higher in the group with flexion than extension fixation (p=0008 and p=0.025, respectively). Furthermore, the total angle of the IP joint limit of extension did not significantly differ between the groups. Conclusion Flexion fixation after flexor tendon rupture achieved an excellent Strickland rating and was more effective than extension fixation, especially in terms of the active flexion ROM of the DIP joint. Flexion fixation might be an alternative to extension fixation because the range of flexion should be greater and might provide a range of finger extension motion equivalent to that of extension fixation.

Evaluation of Anti-Nociceptive, Anti-Inflammatory, and Anti-Fibrotic effects of noscapine against a rat model of Achilles tendinopathy

During tendinopathy, prolonged inflammation results in fibrosis and the adherence of tendons to the adjacent tissues, causing discomfort and movement disorders. As a natural compound, noscapine has several anti-inflammatory and anti-fibrotic properties. Therefore, we aimed to investigate the effects of noscapine against a rat model of tendinopathy. We created a surgical rat model of Achilles tendon damage to emulate tendinopathy. Briefly, an incision was made on the Achilles tendon, and it was then sutured using an absorbable surgical thread. Immediately, the injured area was topically treated with the vehicle, noscapine (0.2, 0.6, and 1.8 mg/kg), or dexamethasone (0.1 mg/kg) as a positive control. During the 19-day follow-up period, animals were assessed for weight, behavior, pain, and motor coordination testing. On day 20th, the rats were sacrificed, and the tendon tissue was isolated for macroscopic scoring, microscopic (H&E, Masson's trichrome, Ki67, p53) analyses, and cytokine secretion levels. The levels of macroscopic parameters, including thermal hyperalgesia, mechanical and cold allodynia, deterioration of motor coordination, tendon adhesion score, and microscopic indices, namely histological adhesion, vascular prominence and angiogenesis, and Ki67 and p53 levels, as well as fibrotic and inflammatory biomarkers (IL-6, TNF-α, TGF-β, VEGF) were significantly increased in the vehicle group compared to the sham group (P < 0.05-0.001 for all cases). In contrast, the administration of noscapine (0.2, 0.6, and 1.8 mg/kg) attenuated the pain, fibrosis, and inflammatory indices in a dose-dependent manner compared to the vehicle group (P < 0.05-0.001). Histological research indicated that noscapine 0.6 and 1.8 mg/kg had the most remarkable healing effects. Interestingly, two higher doses of noscapine had impacts similar to those of the positive control group in both clinical and paraclinical assessments. Taken together, our findings suggested that noscapine could be a promising medicine for treating tendinopathies.

Sensitivity and Accuracy of High-Resolution Ultrasound for Diagnosis of Flexor Tendon Repair Integrity

BACKGROUND

The authors examined whether ultrasound sensitivity, specificity, and accuracy in identifying intact repairs or flexor tendon gapping after zone 2 repair are affected by the number of suture strands crossing the repair or gap or imaging modality (static versus dynamic).

METHODS

A total of 144 fresh-frozen cadaveric digits (thumbs excluded) were randomized to either an intact repair (0-mm gap) or simulated failed repair (4-mm gap), as well as to either a two- or eight-strand locked-cruciate repair of a zone 2 flexor digitorum profundus tendon laceration using 4-0 Fiberwire. Examinations were performed by a blinded musculoskeletal ultrasonographer in static and dynamic modes using an 18-MHz transducer. Gaps were remeasured after scanning, and the final gap width recorded. McNemar exact test was used to determine whether there were differences in sensitivity, specificity, and accuracy affected by modality (static versus dynamic), and chi-square test was used to compare sensitivity, specificity, and accuracy between number of strands (two versus eight) crossing the intact repair or repair gap (≥4 mm).

RESULTS

Sensitivity, specificity, and accuracy improved with increased number of suture strands crossing the repair or gap (eight versus two), irrespective of modality (static versus dynamic), and dynamic compared with static scanning modes, irrespective of number of suture strands crossing the repair or gap site.

CONCLUSIONS

The most sensitive and accurate means of assessing flexor tendon repair integrity and gapping were seen using the dynamic scanning mode. Increased number of suture strands did not negatively affect sensitivity, specificity, or accuracy, regardless of scanning mode (dynamic or static).

The Effect of Timing Between Traumatic Flexor Tendon Injury of the Hand and Surgical Intervention on Repair Failure Rates

Flexor tendon injuries of the hand, especially in zone II, pose a challenge for hand surgeons because of the region's intricate pulley mechanism and local avascularity, and post-surgical complications such as repair failure are not uncommon. One proposed predictor of outcomes following flexor tendon repair has been timing of surgery from initial injury. However, the effect of the timing of flexor tendon repair on failure rates remains controversial and understudied. The purpose of this study was to compare the failure rates of zone II flexor tendon repairs in patients at various time intervals from onset of injury. A retrospective chart review was conducted using data from hand surgery specialists at our level 1 trauma center from January 1, 2010, through May 31, 2020. This retrospective review included 407 zone II flexor tendon repairs. The primary outcome was failure of repair. Among 407 flexor tendon repairs, there were 12 reported repair failures. The failure rate was 2.9%. In the non-failure group, the mean number of days between the date of injury and the date of surgery was 7±13 days. For the failure group, this value was 14±17 days. Repairs occurring within 14 days had a failure rate of 2.3%, while repairs occurring beyond 14 days had a failure rate of 7.7%. This study demonstrates that there is a benefit to repairing the tendon within a 14-day window, as evidenced by a lower failure rate. More research is required to determine if other complications and overall health of the hand are also improved when a repair is performed in a more expedient manner. [Orthopedics. 2024;47(2):113-117.].

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.

Evaluation of Outcome Measures of Zone V Flexor Tendon Injury: A Systematic Review

Background  Flexor tendon injury zone V is a multicomponent soft tissue injury involving tendons, nerves, and vessels. Outcome assessment of repair thus requires evaluation of the hand as a whole rather than solely evaluating tendon function. The purpose of this Preferred Reporting Items for Systematic Reviews and Meta-Analyses -compliant systematic review was to identify and assess the components of outcome measures used in flexor zone V. Methods  A total of 3,761 studies were retrieved from four databases (PubMed, ProQuest, Cochrane Central, and Google Scholar). These studies were then screened for inclusion using a validated screening form. Fifteen articles fulfilling the eligibility criteria were included in the review. Subsequently, the included studies were assessed for methodological quality using the Joanna Brigg Institute tool. Results  Out of the 15 studies, 11 were case series, 3 were cross-sectional studies, and 1 was a randomized controlled trial. Out of 15 included studies, 13 were of low risk, whereas 2 studies suggested moderate risk when assessed for methodological quality using the Joanna Brigg Institute tool. Eight outcome measures were identified, out of which the most frequently used were Total Active Motion by the American Society for Surgery of Hand (TAM-ASSH) and Noaman's criteria. Our study found that Noaman's criteria assessed sensory-motor function and finger deformity in addition to the range of motion (ROM), which was found to be assessed by all the other outcome measures. Conclusion  We concluded that although Buck-Gramcko criteria is well suited for the ROM evaluation, Noaman's criteria, a recently developed outcome measure used exclusively for combined injuries in zone V, took into consideration the implications of nerve injury along with tendon function. Although being specifically designed for combined injuries of tendons, nerves, and vessels in zone V, there is a lack of usage of Noaman's in the literature. There still exists a lack of a consistent and appropriate choice of outcome measure.

Validation of the Efficacy of Ultrasound Speckle Tracking in Measuring Tendon Gliding After Finger Flexor Tendon Repair

OBJECTIVE

Restricted tendon gliding is commonly observed in patients after finger flexor tendon (FFT) repair. The study described here was aimed at quantifying the amount of FFT gliding to evaluate the recovery of post-operative tendons using a 2-D radiofrequency (RF)-based ultrasound speckle tracking algorithm (UST).

METHODS

Ex vivo uniaxial tensile testing of porcine flexor tendons and in vivo isometric testing of human FFT were implemented to verify the efficacy of UST beforehand. The verified UST was then applied to the patients after FFT repair to compare tendon gliding between affected and healthy sides and to investigate its correlation with the joint range of motion (ROM).

RESULTS

Excellent validity was confirmed with the average R2 value of 0.98, mean absolute error of 0.15 ± 0.08 mm and mean absolute percentage error of 5.19 ± 2.43% between results from UST and ex vivo testing. The test-retest reliability was verified with good agreement of ICC (0.90). The affected side exhibited less gliding (p = 0.001) and smaller active ROM (p = 0.002) than the healthy side. Meanwhile, a significant correlation between tendon gliding and passive ROM was found only on the healthy side (ρ = 0.711, p = 0.009).

CONCLUSION

The present study provides a promising protocol to evaluate post-operative tendon recovery by quantifying the amount of FFT gliding with a validated UST. FFT gliding in patients with different levels of ROM restriction should be further explored for categorizing the severity of tendon adhesion.

Multilayer amnion-PCL nanofibrous membrane loaded with celecoxib exerts a therapeutic effect against tendon adhesion by improving the inflammatory microenvironment

Tendon adhesion is a common complication after tendon surgery. The inflammatory phase of tendon healing is characterized by the release of a large number of inflammatory factors, whose mediated excessive inflammatory response is an important cause of tendon adhesion formation. Nonsteroidal anti-inflammatory drugs(NSAIDs) were used to prevent tendon adhesions by reducing the inflammatory response. However, recent studies have shown that the NSAIDs partially impairs tendon healing. Therefore, optimizing the anti-adhesive membrane loaded with NSAIDs to mitigate the effects on tendon healing requires further in-depth study. Amniotic membranes(AM) are natural polymeric semi-permeable membranes from living organisms that are rich in matrix, growth factors, and other active ingredients. In this study, we used electrostatic spinning technology to construct multifunctional nanofiber membranes of the PCL membrane loaded with celecoxib and AM. In vitro cellular assays revealed that celecoxib-loaded PCL membranes significantly inhibited the adhesion and proliferation of fibroblasts with increasing concentrations of celecoxib. In a rabbit tendon repair model, biomechanical tests further confirmed that the PCL membrane loaded with celecoxib had better anti-adhesion effects. Further experimental studies revealed that the PCL/AM membrane improved the inflammatory microenvironment by downregulating the expression of pro-inflammatory factors such as COX-2, IL-1β, and TNF-α proteins; and inhibiting the synthesis of COL I and COL Ⅲ. The PCL/AM membrane can continuously release celecoxib to reduce the inflammatory response and deliver growth factors to the damaged area to build a suitable microenvironment for tendon repair, which provides a new direction to improve the repair efficiency of tendon.

Carbodiimide-Derivatized Synovial Fluid for Tendon Graft Coating Improves Long-Term Functional Outcomes of Flexor Tendon Reconstruction

BACKGROUND

Flexor digitorum profundus (FDP) tendon injury is common in hand trauma, and flexor tendon reconstruction is one of the most challenging procedures in hand surgery because of severe adhesion that exceeds 25% and hinders hand function. The surface properties of a graft from extrasynovial tendons are inferior to those of the native intrasynovial FDP tendons, which has been reported as one of the major causations. Improved surface gliding ability of the extrasynovial graft is needed. Thus, this study used carbodiimide-derivatized synovial fluid and gelatin (cd-SF-gel) to modify the surface of the graft, thus improving functional outcomes using a dog in vivo model.

METHODS

Forty FDP tendons from the second and fifth digits of 20 adult women underwent reconstruction with a peroneus longus (PL) autograft after creation of a tendon repair failure model for 6 weeks. Graft tendons were either coated with cd-SF-gel ( n = 20) or not. Animals were euthanized 24 weeks after reconstruction, and digits were collected after the animals were euthanized for biomechanical and histologic analyses.

RESULTS

Adhesion score (cd-SF-gel, 3.15 ± 1.53; control, 5 ± 1.26; P < 0.00017), normalized work of flexion (cd-SF-gel, 0.47 ± 0.28 N-mm/degree; control, 1.4 ± 1.45 N-mm/degree; P < 0.014), and distal interphalangeal joint motion (cd-SF-gel, 17.63 ± 6.77 degrees; control, 7.07 ± 12.99 degrees; P < 0.0015) in treated grafts all showed significant differences compared with nontreated grafts. However, there was no significant difference in repair conjunction strength between the two groups.

CONCLUSION

Autograft tendon surface modification with cd-SF-gel improves tendon gliding ability, reduces adhesion formation, and enhances digit function without interfering with graft-host healing.

CLINICAL RELEVANCE STATEMENT

The authors demonstrate a clinically relevant and translational technology by using the patient's own synovial fluid to "synovialize" an autologous extrasynovial tendon graft to improve functional outcomes following flexor tendon reconstruction.

Comparative sensitivity and accuracy of 24 vs. 18 MHz ultrasound probes for the diagnosis of flexor tendon repair integrity

Purpose

To determine whether a 24 MHz transducer significantly improves sensitivity, specificity and accuracy in evaluating flexor tendon repair integrity compared with an 18 MHz transducer.

Methods

One hundred and twelve cadaveric digits were randomised to an intact repair or simulated 'failed' repair, and to a two- or eight-strand repair of a flexor digitorum profundus laceration. A blinded sonologist evaluated specimens in static mode using 18 and 24 MHz transducers. Gaps were remeasured after scanning, and final gap width recorded. McNemar's exact test calculated differences between sensitivity, specificity and accuracy, and chi-squared test to compare sensitivity, specificity and accuracy between number of strands (2 vs. 8) and repair gap (≥4 mm).

Results

The 24 MHz transducer had higher sensitivity (81 vs. 59%), lower specificity (67 vs. 70%) and higher overall accuracy (74 vs. 64%), than the 18 MHz transducer. The difference for sensitivity was significant (P = 0.011), but not differences for specificity and overall accuracy (P > 0.05). Pearson's correlation (r = 0.61) demonstrated a moderate-to-strong positive correlation between measured and true gap sizes. Increased number of suture strands (2 vs. 8) did not impair sensitivity, specificity nor accuracy.

Discussion

Ultrasound may tend to overestimate gap width, and a slight risk that some intact repairs, or those with small, clinically insignificant gaps may undergo surgical exploration that may not be indicated.

Conclusions

A 24 MHz transducer is a more sensitive and accurate transducer for assessing flexor tendon repair integrity and measuring small gaps.

Biomechanical Evaluation of a Tubular Braided Construct for Primary Deep Flexor Tendon Surgery

PURPOSE

Immediate postoperative mobilization has been shown to avoid adhesion formation and improve range of motion after flexor tendon repair. A tubular braided construct was designed to allow for these rehabilitation protocols.

METHODS

In this ex vivo study, 92 ovine flexor tendons were divided randomly into 2 equal groups. After creating a transection, the tendons of the first group were repaired using a tubular braided construct. This construct, consisting of a tubular braid of polypropylene and polyethylene terephthalate fibers, exerts a grasping effect on the tendon ends. The control group received a multistrand modified Kessler repair with a looped polydioxanone suture (PDS) 4-0 suture and a Silfverskiöld epitendinous repair using an Ethilon 6-0 suture. After the repair, a static and an incremental cyclic tensile test was performed until failure.

RESULTS

During the static test, the tubular braid resulted in a significantly higher load at 3 mm gap formation (86.3 N ± 6.0 vs 50.1 N ± 11.6), a higher ultimate load at failure (98.3 N ± 12.7 vs 63 N ± 11.1), higher stress at ultimate load (11.8 MPa ± 1.2 vs 8.1 MPa ± 3.1), and higher stiffness (7.1 N/mm ± 2.9 vs 8.7 N/mm ± 2.2). For the cyclic tests, survival analyses for 1-, 2- and 3-mm gap formation and failure demonstrated significant differences in favor of the tubular braided construct.

CONCLUSION

The tubular braided construct withstands the required loads for immediate rehabilitation not only in static tests, but also during cyclic tests. This is in contrast with the control group, where sufficient strength is reached during static tests, but failures occur below the required loads during cyclic testing.

CLINICAL RELEVANCE

The tubular braided construct provides a larger safety margin for immediate intensive rehabilitation protocols.

Relative efficacy of three different tendon repairs in complete flexor digitorum profundus laceration in Zone I: A randomized controlled study

Hand flexor tendon injuries are common and biomechanically challenging to achieve good functional outcomes. Several approaches using the Pennington-modified Kessler repair technique have been attempted, but high-level evidence is still lacking. Here, we evaluated the relative efficacy of three versions of the Pennington-modified Kessler technique in repairing complete flexor digitorum profundus (FDP) laceration in Zone 1. We conducted a 2-year, single-center, double-blind, randomized clinical trial involving 85 patients with 105 digits enrolled between June 1, 2017 and January 1, 2019. Eligible participants were 20-60 years of age and underwent tendon repair in the acute phase for complete FDP laceration distal to the insertion of the superficial flexor tendon. The digits were randomized 1:1:1 to three treatment groups: (1) Pennington-modified Kessler repair; (2) Pennington-modified Kessler repair followed by circumferential tendon suture; or (3) Pennington-modified Kessler repair followed by circumferential epitenon suture. The primary endpoint was total active range of motion (TAROM) at 2 years after the initial surgery. The secondary endpoint was the reoperation rate. Compared with group 1, both techniques for peripheral suture were associated with a decrease in TAROM at 2 years after surgery. The total reoperation rates of the three groups were 11.4%, 18.2%, and 17.6%, and we found no significant differences among the three groups possibly due to the limited sample size. Unexpectedly, among participants with complete FDP laceration in Zone I, both circumferential-tendon and circumferential-epitenon sutures caused worsening of TAROM after 2 years. No conclusions can be drawn regarding reoperation rates among the groups. Level of evidence: Therapeutic level I.

Approach to Tendinopathies of the Upper Limb: What Works

Tendinopathies are some of the most common diagnoses treated by hand surgeons. Diagnoses such as trigger digit, de Quervain tenosynovitis, extensor carpi ulnaris tendinitis, and epicondylitis often resolve with nonoperative treatment and/or a single ambulatory procedure. When symptoms persist or worsen after surgery, patients are disappointed and treatment can be challenging. This article reviews practical points in evaluation of such cases, and surgical options that work in revision scenarios.

M2 Macrophage Membrane-Mediated Biomimetic-Nanoparticle Carrying COX-siRNA Targeted Delivery for Prevention of Tendon Adhesions by Inhibiting Inflammation

Tendon adhesion is the most common outcome of tendon or tendon-to-bone healing after injury. Our group developed a hydrogel-nanoparticle sustained-release system previously to inhibit cyclooxygenases (COXs) expression and consequently prevent tendon adhesion and achieved satisfactory results. However, effective treatment of multiple tendon adhesions is always a challenge in research on the prevention of tendon adhesion. In the present study, an M2M@PLGA/COX-siRNA delivery system is successfully constructed using the cell membranes of M2 macrophages and poly (lactic-co-glycolic acid) (PLGA) nanoparticles. Targeting properties and therapeutic effects are observed in mice or rat models of flexor digitorum longus (FDL) tendon injury combined with rotator cuff injury. The results showed that the M2M@PLGA/COX-siRNA delivery system has low toxicity and remarkable targeting properties to the injured areas. Treatment with the M2M@PLGA/COX-siRNA delivery system reduced the inflammatory reaction and significantly improved tendon adhesion in both the FDL tendon and rotator cuff tissues. These findings indicate that the M2M@PLGA delivery system can provide an effective biological strategy for preventing multiple tendon adhesions.

Prevention strategies of postoperative adhesion in soft tissues by applying biomaterials: Based on the mechanisms of occurrence and development of adhesions

Postoperative adhesion (POA) widely occurs in soft tissues and usually leads to chronic pain, dysfunction of adjacent organs and some acute complications, seriously reducing patients' quality of life and even being life-threatening. Except for adhesiolysis, there are few effective methods to release existing adhesion. However, it requires a second operation and inpatient care and usually triggers recurrent adhesion in a great incidence. Hence, preventing POA formation has been regarded as the most effective clinical strategy. Biomaterials have attracted great attention in preventing POA because they can act as both barriers and drug carriers. Nevertheless, even though much reported research has been demonstrated their efficacy on POA inhibition to a certain extent, thoroughly preventing POA formation is still challenging. Meanwhile, most biomaterials for POA prevention were designed based on limited experiences, not a solid theoretical basis, showing blindness. Hence, we aimed to provide guidance for designing anti-adhesion materials applied in different soft tissues based on the mechanisms of POA occurrence and development. We first classified the postoperative adhesions into four categories according to the different components of diverse adhesion tissues, and named them as "membranous adhesion", "vascular adhesion", "adhesive adhesion" and "scarred adhesion", respectively. Then, the process of the occurrence and development of POA were analyzed, and the main influencing factors in different stages were clarified. Further, we proposed seven strategies for POA prevention by using biomaterials according to these influencing factors. Meanwhile, the relevant practices were summarized according to the corresponding strategies and the future perspectives were analyzed.

Surgical Considerations for Flexor Tendon Repair: Timing and Choice of Repair Technique and Rehabilitation

Flexor tendon injuries are common and occur mostly due to penetrating trauma. Surgical repair is required for complete tendon lacerations, and many techniques exist. This article reviews the principles of tendon structure, function, healing, and anatomy. Repair techniques are discussed in detail for each flexor tendon zone. Postoperative rehabilitation greatly influences outcomes, and several protocols are described.

Hand Flexor Tendon Repair: From Biology to Surgery and Rehabilitation

Tendon biology and anatomy are crucial to manage hand flexor tendon injuries, not only for surgical treatment but also for rehabilitation; surgeon and physical therapist have to choose zone by zone the best way to manage and restore the normal function of hand flexor tendons.

Tenolysis and Salvage Procedures

Complications in flexor tendon repair are common and include tendon rupture, adhesion formation, and joint contracture. Risk factors include preexisting conditions, gross contamination, concurrent fracture, early unplanned loading of the repaired tendon, premature cessation of splinting, and aggressive early active range of motion protocols with insufficient repair strength. Rupture of a repaired tendon should be followed by early operative exploration, debridement, and revision with a four-core strand suture and nonbraided epitendinous suture. Wide-awake flexor tenolysis should be considered when adhesion formation results in the plateaued range of motion, and passive motion exceeds active motion. Two-staged reconstruction is recommended when injury results in excessive scaring, joint contracture, or an incompetent pulley apparatus.

Flexor Tendon Adhesion Formation: Current Concepts

Over the years, various physical and chemical/biological methods of inhibiting adhesion formation have been developed, focusing on how to suppress healing around the tendon and not inhibit healing within the tendon. Unfortunately, however, these methods are accompanied by drawbacks, both large and small, and no absolute antiadhesion method capable of maintaining tendon repair strength has yet been developed. Recent innovations in biomaterials science and tissue engineering have produced new antiadhesion technologies, such as barriers combined with cytokines and cells, which have improved outcomes in animal models, and which may find clinical relevance in the future.

Wide-Awake Local Anesthesia No Tourniquet (WALANT) for Flexor Tendon Repairs as Change in Practice During the COVID-19 Pandemic: A Retrospective Cohort Study With Outcomes

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic forced many changes. In our unit, there was a significant shift from traditional anesthesia (TA) which included general or regional anesthesia, to Wide-Awake Local Anesthesia No Tourniquet (WALANT) for the treatment of flexor tendon injuries. Zones I and II injuries have always been a challenge. The primary aim of this study is to compare the 12-week range of motion (ROM) flexor tendon repair outcomes between the TA group and wide-awake (WA) group patients. The secondary aim is to compare the complications and the follow-up rate between the two groups.

METHODS

All patients who underwent a primary finger flexor tendon repair in zone I or II without tendon graft for closed avulsions or open lacerations between April 2020 and March 2021 were included in the study. Electronic medical records were reviewed to record demographics, follow-up, ROM outcomes and complications.

RESULTS

Forty-four patients with 49 injured fingers were in the WA group, and 24 patients with 37 injured fingers were in the TA group. A complete follow-up with 12-week ROM outcomes was available for 15 patients with 16 injured fingers in the WA group and nine patients with 13 injured fingers in the TA group. Excellent to good outcomes in the WA group were reported in 56% of the cases versus 31% in the TA group, although the difference was not statistically significant. There were similar complications in both groups, with an overall rupture rate of 11.6%, a tenolysis rate of 3.5% and a reoperation rate of 9.3%. Complete 12-week follow-up was completed by 41% of patients overall after taking tendon ruptures into account.

CONCLUSIONS

This is one of the first studies comparing zones I and II flexor tendon ROM outcomes between WA anesthesia and TA. Overall, there was a trend toward superior ROM outcomes in the WA group, with similar complication rates in both groups. The difference between ROM outcomes was not statistically significant and the small sample size undermined the strength of the study. To provide stronger evidence, better-designed prospective studies are suggested that would compare WA techniques with TA techniques.

Clinical Outcomes After Aggressive Active Early Motion and Modified Kleinert Regimens: Comparison of 2 Consecutive Cohorts

BACKGROUND

Modern multistrand repairs can withstand forces present in active flexion exercises, and this may improve the outcomes of flexor tendon repairs. We developed a simple home-based exercise regimen with free wrist and intrinsic minus splint aimed at facilitating the gliding of the flexor tendons and compared the outcomes with the modified Kleinert regimen used previously in the same institution.

METHODS

We searched the hospital database to identify flexor tendon repair performed before and after the new regimen was implemented and invited all patients to participate. The primary outcome was total active range of motion, and secondary outcomes were Disabilities of Arm, Shoulder, and Hand; grip strength; globally perceived function; and the quality of life.

RESULTS

The active range of motion was comparable between the groups (mean difference = 14; 95% confidence interval [CI], -8 to 36; P = .22). Disabilities of Arm, Shoulder, and Hand; grip strength; global perceived function; and health-related quality of life were also comparable between the groups. There was 1 (5.3%) rupture in the modified Kleinert group and 4 (15.4%) in the early active motion group (relative risk = 0.3; 95% CI, 0.04-2.5; P = .3).

CONCLUSIONS

Increasing active gliding with a free wrist and intrinsic minus splint did not improve the clinical outcomes after flexor tendon injury at a mean of 38-month follow-up.

Risk factors associated with tendon adhesions after hand tendon repair

Background

Tendon adhesions after hand tendon repair are one of the most difficult complications of hand surgery and can cause severe disability. This study aimed to assess the risk factors associated with tendon adhesions after hand tendon repair to provide a theoretical foundation for the early prevention of tendon adhesions in patients with tendon injuries. Moreover, this study intends to increase doctors' awareness of the issue and serves as a reference for developing new prevention and treatment strategies.

Methods

We retrospectively analyzed 1,031 hand trauma cases that underwent repair after finger tendon injury in our department between June 2009 and June 2019. Tendon adhesions, tendon injury zones, and other relevant information were collected, summarized, and analyzed. The significance of data was determined using a t-test or Pearson's chi-square test, and odds ratios (OR) were calculated using logistic regression tests to describe factors associated with post-tendon repair adhesions.

Results

A total of 1,031 patients were enrolled in this study. There were 817 males and 214 females with an average age of 34.98 (2-82) years. The injured side included 530 left and 501 right hands. Postoperative finger tendon adhesions occurred in 118 cases (11.45%), including 98 males and 20 females, 57 left and 61 right hands. The risk factors for the total sample in the descending order were degloving injury, no functional exercise, zone II flexor tendon injury, time from injury to surgery >12 h, combined vascular injury, and multiple tendon injuries. The flexor tendon sample shared the same risk factors as the total sample. Risk factors for the extensor tendon sample were degloving injury, no functional exercise.

Conclusions

Clinicians should pay close attention to patients with tendon trauma in hand having the following risk factors: degloving injury, zone II flexor tendon injury, lack of functional exercise, time from injury to surgery >12 h, combined vascular injury, and multiple tendon injuries. Due to the high risk of post-repair adhesions in patients with the conditions mentioned above, individualized treatment measures should be designed for the risk factors, and postoperative functional exercise of the hand is required.

Energy-Supporting Enzyme-Mimic Nanoscaffold Facilitates Tendon Regeneration Based on a Mitochondrial Protection and Microenvironment Remodeling Strategy

Tendon injury is a tricky and prevalent motor system disease, leading to compromised daily activity and disability. Insufficient regenerative capability and dysregulation of immune microenvironment are the leading causes of functional loss. First, this work identifies persistent oxidative stress and mitochondrial impairment in the regional tendon tissues postinjury. Therefore, a smart scaffold incorporating the enzyme mimicry nanoparticle-ceria nanozyme (CeNPs) into the nanofiber bundle scaffold (NBS@CeO) with porous, anisotropic, and enhanced mechanical properties is designed to innovatively explore a targeted energy-supporting repair strategy by rescuing mitochondrial function and remodeling the microenvironment favoring endogenous regeneration. The integrated CeNPs scavenge excessive reactive oxygen species (ROS), stabilize the mitochondria membrane potential (ΔΨm), and ATP synthesis of tendon-derived stem cells (TDSCs) under oxidative stress. In a rat Achilles tendon defect model, NBS@CeO reduces oxidative damage and accelerates structural regeneration of collagen fibers, manifesting as recovering mechanical properties and motor function. Furthermore, NBS@CeO mediates the rebalance of endogenous regenerative signaling and dysregulated immune microenvironment by alleviating senescence and apoptosis of TDSCs, downregulating the secretion of senescence-associated secretory phenotype (SASP), and inducing macrophage M2 polarization. This innovative strategy highlights the role of NBS@CeO in tendon repair and thus provides a potential therapeutic approach for promoting tendon regeneration.

Practice Patterns in Operative Flexor Tendon Laceration Repair: A 15-Year Analysis of Continuous Certification Data from the American Board of Plastic Surgery

The American Board of Plastic Surgery has been collecting practice data on operative repair of flexor tendon lacerations since 2006, as part of its Continuous Certification program.

Enhanced tendon healing by a tough hydrogel with an adhesive side and high drug-loading capacity

Hydrogels that provide mechanical support and sustainably release therapeutics have been used to treat tendon injuries. However, most hydrogels are insufficiently tough, release drugs in bursts, and require cell infiltration or suturing to integrate with surrounding tissue. Here we report that a hydrogel serving as a high-capacity drug depot and combining a dissipative tough matrix on one side and a chitosan adhesive surface on the other side supports tendon gliding and strong adhesion (larger than 1,000 J m-2) to tendon on opposite surfaces of the hydrogel, as we show with porcine and human tendon preparations during cyclic-friction loadings. The hydrogel is biocompatible, strongly adheres to patellar, supraspinatus and Achilles tendons of live rats, boosted healing and reduced scar formation in a rat model of Achilles-tendon rupture, and sustainably released the corticosteroid triamcinolone acetonide in a rat model of patellar tendon injury, reducing inflammation, modulating chemokine secretion, recruiting tendon stem and progenitor cells, and promoting macrophage polarization to the M2 phenotype. Hydrogels with 'Janus' surfaces and sustained-drug-release functionality could be designed for a range of biomedical applications.

Initial Experience with the PONTiS Tendon Repair System in Traumatic Upper Extremity Injuries

BACKGROUND

Tendon injuries of the upper extremity remain a common surgical condition requiring prompt intervention. We review our initial experience with the PONTiS flexor tendon repair system (PFRS) - a knotless, multifilament stainless steel crimp system.

METHODS

Consecutive patients undergoing repair by our plastic and orthopedic surgeons with the PFRS were reviewed from 2015-2017. Multivariate risk and Kaplan-Meier survival analyses were performed to assess risk factors associated with complications.

RESULTS

Eighty-one patients with mean follow up of 75 days (range 0 - 33 months) were identified. The most common demographics of our patients were right-handed (82.9%), male (71.4%), laborer (35.7%), sustaining laceration injuries (77.1%) at zone 2 (27.2%). There was an average of 3.7 tendon injuries per patient. Associated injuries included fractures (21.4%), arterial injuries (24.3%), and nerve injuries (61.4%). Thirteen (16.0%) patients developed complications: adhesions/contracture (4), rupture (2), flap ischemia (2), arterial thrombosis (1), wound dehiscence (1), tendon lag (1), and erosion of the PFRS through soft-tissue grafts (2). Multivariate analysis identified poor soft-tissue coverage (OR 9.990; p=0.043) and zone 2 involvement (OR 7.936; p=0.016) as risk factors, while epitendinous repairs (OR 0.096; p=0.010) were protective against complications.

CONCLUSIONS

The PFRS system is rapid and simple to deploy and advantageous especially in multiple traumatic tendon injuries. Compared to traditional suture repair, it has a comparable overall complication profile but superior rupture and tenolysis rates. We advise use with caution in cases with poor soft tissue coverage to minimize risks of extrusion and strongly recommend the use of epitendinous sutures concurrently to limit complications.

Outcomes at 3 Months of a Place and Active Hold Method of Flexor Tendon Rehabilitation Following Zone II Injury

Background: Previous studies have shown that outcomes following a place and active hold (PAH) are better than a passive flexion protocol after a two-strand core-suture repair of flexor tendons injuries in zone II. This study aims to determine the outcomes of a PAH protocol of flexor tendon rehabilitation following a four-strand core-suture plus an epitendinous suture repair of the flexor digitorum profundus (FDP) combined with a simple horizontal loop repair of the flexor digitorum superficialis (FDS). Methods: This is a prospective study of patients with complete injury to both flexor tendons in zone II. All tendons were repaired with a simple horizontal loop for FDS and four-strand core-suture plus epitendinous suture for FDP. The PAH protocol was used postoperatively for 6 weeks. The outcome was evaluated using flexion contracture and total active motion (TAM), interpreted using Strickland criteria and categorised as excellent, good, fair and poor at 6 weeks and 3 months. The linear regression model was used to determine predictors of outcomes. Results: The study included 32 patients with flexor tendon injury in 46 fingers. No repairs ruptured, and 24 (52%) digits achieved good or excellent motion 6 weeks after surgery using the Strickland criteria. According to the Strickland criteria, 41 (89%) digits ranked as excellent and good with no poor result at a 3-month follow-up. Four patients had 5-10° of flexion contracture. Age was the predictor of TAM at 6 weeks and accounted for 13% of its variation. Improvement of TAM from 6 weeks to 3 months was related to age and flexion contracture at 6 weeks. Conclusions: The PAH protocol can be considered a safe technique for flexor rehabilitation after four-strand core-suture repair of FDP in zone II. Level of Evidence: Level IV (Therapeutic).

Effect of electromyographic biofeedback training on functional status in zone I-III flexor tendon injuries: a randomized controlled trial

BACKGROUND

Despite advances in hand therapy and surgery, functional deficits persist after flexor tendon repair especially in zone I-III. This suggests that methods applied may be insufficient. Electromyographic (EMG) biofeedback may provide an effective tendon gliding through visual and auditory feedback.

PURPOSE

The purpose of this study was to investigate the effect of EMG biofeedback training applied in addition to early passive motion protocol on functional status in zone I-III flexor tendon injuries.

METHODS

Patients were randomly assigned into two groups, each consisted of 11 patients. In addition to early passive motion method, EMG biofeedback training was applied in the first group. The second group was followed only with early passive motion protocol. Joint range of motion (ROM), Michigan Hand Outcomes Questionnaire (MHQ) and grip strength were evaluated.

RESULTS

There were no significant differences between the groups in terms of the ROM, MHQ scores and grip strength (p ≥ .087). However, there were clinically important differences in the results of the 12th week ROM (effect size = 0.70), 24th week activity of daily living (ADL) score in MHQ (effect size = 0.68), 12th week gross, tip pinch and lateral grip strength (effect sizes = 0.59, 0.52, 0.81, respectively) and 24th week gross, tip pinch and lateral grip strength (effect sizes = 0.69, 0.73, 0.69, respectively) between the two groups.

CONCLUSIONS

EMG biofeedback training was clinically but not statistically superior to early passive motion method in terms of the effect on functional status.

Outcome measurement in adult flexor tendon injury: A systematic review

BACKGROUND

Defining the optimal, evidence-based management of flexor tendon injury remains challenging. Lack of consensus on which measures to use to assess the outcome of interventions is a key issue, especially with regard to patient-reported outcome measures (PROMs). This systematic review defines the landscape of outcome measurement in studies on interventions for flexor tendon injuries to guide future research.

METHODS

A PRISMA-compliant systematic review was conducted using bespoke search strategies applied to MEDLINE, EMBASE, PsycINFO, CENTRAL, CINAHL and AMED. A protocol was developed and registered prospectively (CRD42020186780). We identified all studies describing adult patients undergoing interventions for acute hand flexor tendon injuries.

RESULTS

Of the 4844 studies, 114 studies met the final inclusion criteria for evaluating the outcomes of 8127 participants with 9071 injured digits. Studies included 24 randomised controlled trials, 19 cohort studies and 61 case series. Nine different PROMs were used in 24 studies (22%): three site-specific PROMs, one generic quality-of-life measure and four visual analogue scales. Clinician-reported outcome measures were used in 103 studies (96%), such as the range of motion reported in 102 studies (94%). Adverse outcomes were reported in 96 studies (89%), with the most frequently reported adverse outcomes being tendon rupture and infection. Re-operation was reported in 21 studies (19%). The most frequently reported health economic outcome measure was the length of work absence, reported in ten studies (9%).

CONCLUSIONS

There is variability in the use of outcome measures used to study interventions for flexor tendon injuries. An independent systematic review of the psychometric properties of the identified outcome measures and a specific multi-stakeholder consensus process may support optimal choice and standardisation for future studies.

Management and outcomes of flexor tendon repairs at a peripheral hospital: a New Zealand case series study

BACKGROUND

Current evidence for flexor tendon repair management and outcomes performed at peripheral centres is unclear. Most studies are based on evidence from specialist hand centres. This study evaluated a peripheral hospital in New Zealand; where all flexor tendon repairs were performed by a generalist Orthopaedic service. The purpose of the study was to benchmark management and outcomes from a peripheral hospital in comparison to international standards.

METHODS

A retrospective single-centre consecutive case series of Zones I and II flexor tendon repairs was extracted between 1 January 2014 and 1 January 2018. Medical records were used to evaluate management and outcomes of repairs. Hand therapy notes were used to evaluate rehabilitation protocols provided. The primary objective was to measure re-rupture and re-operation rates. Secondary objectives included auditing operative management and hand therapy compliance.

RESULTS

Forty-six patients (76 tendon repairs) were included in our final analysis. Mean follow up time to last clinical appointment was 11.8 weeks, and to last patient episode was 4.9 years. Most patients received timely surgery with a four-core repair using 3-0 or larger suture. All hand therapy followed a controlled active motion protocol. The re-operation rate was 19.6% (P = <0.05) and the re-rupture rate was 8.7% (P = 0.28).

CONCLUSIONS

Most flexor tendon injuries at this peripheral centre were managed according to international standards. However, high complication rates including re-operation and re-rupture occurred. Due to a lack of local comparison studies, confounding factors cannot be excluded as a contributor for these results.

Operative outcomes for wide awake local anesthesia versus regional and general anesthesia for flexor tendon repair

Operative repair of flexor tendons after traumatic injury may be performed under general anesthesia (GA), regional blocks, or a wide-awake local anesthesia no tourniquet (WALANT) technique. To our knowledge there are currently no large-scale reports evaluating outcomes of flexor tendon repair in patients where wide-awake anesthesia was utilized in comparison to regional anesthesia (RA) and general anesthesia. We performed a retrospective analysis of patients who underwent treatment for flexor tendon injuries at a tertiary referral center for hand surgery over a two-year period. A total of 151 patients were included (53 WALANT, 57 RA, and 41 GA) and a total of 251 tendons were repaired (63 WALANT, 104 RA and 84 GA). No statistically significant difference was observed in rates of tendon rupture, adhesions, infection, or hand function. Flexor tendon repair under WALANT is found to be safe and presents comparable operative and functional outcomes to more traditional anesthetic techniques. Additional advantages, including the ability to test the repair intraoperatively, patient education, and the potential for boosting theatre efficiency. Further studies, preferably utilizing a randomized trial methodology, may further elucidate the benefits and risks of WALANT versus regional and general anesthesia.

Tendon Reconstruction With Cadaveric Allograft in a Patient With Flexor Tendon Injury Without Treatment for Six Months

We present the case of an 18-year-old male patient with a penetrating lesion at zone II of the flexor compartment of the left hand. During surgery, complete reabsorption of the second deep and superficial flexor tendons was evidenced, prompting the decision to perform a two-stage procedure. First, a spacer was placed, and pulley reconstruction was performed. Six weeks later, we placed a cadaveric allograft and splint with the Kleinert-Duran technique for proper rehabilitation. Our case report highlights that a two-stage procedure with an allograft is a feasible technique resulting in good post-surgical functional status despite tendon reabsorption and six months between trauma and surgical intervention.

The impact of transverse components on 4-strand tendon repairs

We investigated the effects of the transverse components of a tendon core suture on tensile resistance and strength of 4-strand repairs. Forty-four pig flexor tendons were repaired with one of the following four methods: double Tsuge, U-shaped, 4-strand cross and 4-strand rectangular repairs. We recorded the number of the repaired tendons that formed a 2 mm gap between the tendon ends during cyclic loading for 20 cycles, stiffness of the tendon at the 1st and 20th cycle, gap distance at the repair site and ultimate strength of the repair at the 20th cycle. When transverse components were added to the core suture, a greater number of tendons formed a 2 mm gap during cyclic loading. The stiffness gradually decreased, and the repair site's gap distance after cyclic loading increased with the presence of transverse components of the sutures. We conclude that the core suture's transverse components negatively impact the tensile resistance of 4-strand tendon repairs.

The impact of transverse components on resistance and ultimate strength of 6-strand tendon repairs

We assessed the effects of tendon core sutures' transverse components on the tensile resistance of two commonly used 6-strand tendon repairs. Tang and Yoshizu #1 repairs (6-strand) were tested and compared with 4-strand rectangular and double Kessler sutures (4-strand). A total of 40 pig flexor tendons were tested under cyclic loading. We recorded the number of tendons that formed a 2-mm gap between two tendon ends during 20 cycles of cyclic loading test, stiffness at the 1st and 20th loading cycle, and gap distance at the repair site and the ultimate repair strength at the 20th cycles. We found that the Yoshizu #1 repairs were more prone to form gaps and their ultimate strength was significantly lower than that of the Tang repair. The transverse components in a 6-strand repair affect gap formation and failure strength.

Measurement of finger joint motion after flexor tendon repair: smartphone photography compared with traditional goniometry

The purpose of our study was to determine whether smartphone photography is as reliable and valid as clinical goniometry for measuring interphalangeal joint range of motion. We conducted a retrospective review of 37 fingers in 33 patients after flexor tendon repair. The measurements on photographs taken with a smartphone by a surgeon were compared with manual measurements with goniometry by the same surgeon. Pearson coefficients and interclass correlation coefficients were all above 0.85, and Bland-Altman analysis demonstrated that at least 35 of 37 measurements were within the 95% confidence interval in all variables. According to the Tang criteria, the total number of excellent and good results were equivalent according to both methods. There was high interobserver reliability between measurements by surgeons and a therapist. We conclude that if the pictures are properly taken, the measurement of the angles in the smartphone pictures are as reliable as measuring the angles with goniometry and that grading of the results according to the two methods gives identical results.

Morphological changes of macrophages and their potential contribution to tendon healing

Poor healing ability and adhesion formation greatly hinder the recovery of injured tendon function. Previously, our local sustained gene delivery system by using cyclooxygenases (COX-1 and COX-2)-engineered miRNA plasmid/nanoparticles loaded hydrogel significantly inhibited adhesion formation and promoted tendon healing. The present study aims to study morphological changes of the macrophages in the healing tendons after above treatment with the hydrogel. Firstly, we assessed the therapeutic effect of localized delivery of the hydrogel on cyclooxygenases in the injured rat Achilles tendon model. We found ultimate strengths of the healing tendons were significantly increased at week 2 and 3. We then studied the distribution of macrophages before and after tendon injury, and found macrophages were rapidly recruited into injured sites of tendons. After being isolated and cultured, macrophages were transfected with 6-Carboxyfluorescein (FAM) labeled siRNA/nanoparticles and presented a high transfection efficiency (>70%). We further compared the change of iNOS/CD206 in macrophages between negative control siRNA/nanoparticle group and COX siRNA/nanoparticle group. The major finding is that the morphology of the macrophages changed from type I macrophages to type II macrophages after transfection of COX siRNA/nanoparticles in vitro. Subsequently, rat Achilles tendon cells were cultured with supernatant collected from macrophages transfected with negative control siRNA/nanoparticles and COX siRNA/nanoparticles, and the proliferation of tendon cells was significantly increased in COX siRNA/nanoparticle supernatant group. Because type II macrophages are responsible for tissue repair, the changes in macrophage polarization from M1 to M2 may be one of the important events in promoting the tendon healing.

Biomechanical study of a newly developed continuous double knots technique compared with the 4-strand double-modified Kessler technique for flexor tendon repair

PURPOSE

In this study we compare the biomechanical properties of a novel suture technique that we developed called the continuous double knots technique for repairing flexor tendon injuries with the standard 4-strand double-modified Kessler technique.

METHODS

This was an experimental study. Eighty porcine flexor digitorum profundus tendons were harvested and divided randomly into two groups of 40. The first group (N = 40) was repaired using the 4-strand double modified Kessler technique and the second group (N = 40) was repaired using our new continuous double knots technique. The two groups were randomly divided and the ultimate failure load (n = 20) and cyclic testing to failure (n = 20) were compared.

RESULTS

The mean ultimate failure load was 25.90 ± 7.11 (N) and cyclic testing to failure 88 ± 47.87 (cycles) for the 4-strand double modified Kessler technique and 34.56 ± 6.60 (N) and 189 ± 66.36 (cycles) for our new continuous double knots technique. The T-test revealed a significant difference between the 2 techniques (p < 0.05). In terms of biomechanical properties in tendon repair, the continuous double knots technique group had a higher tensile strength than the 4-strand double-modified Kessler technique group. There were also significant differences between the ultimate failure load and cyclic testing to failure for the flexor tendon sutures.

CONCLUSIONS

The continuous double knots technique suture technique had significantly higher maximum tensile strength and cyclic testing than the 4-strand double modified Kessler technique in an in vitro study, and in thus an optional technique for flexor tendon repair.

The effect of fibrin formulation on cell migration in an in vitro tendon repair model

BACKGROUND

The purpose of this study was to determine the effect of fibrinogen concentration on cell viability and migration in a tissue culture tendon healing model.

METHODS

Forty-eight canine flexor digitorum profundus tendons were randomly divided into three groups. In each group the tendons were lacerated and repaired augmented with a canine bone marrow stromal cell seeded fibrin interposition patch using either 5 mg/ml fibrinogen and 25 U/ml thrombin (physiological as a control), 40 mg/ml fibrinogen and 250 U/ml thrombin (low adhesive), or 80 mg/ml fibrinogen and 250 U/ml thrombin (high adhesive). The sutured tendons were cultured for two or four weeks.

RESULTS

Failure load was not significantly different among the groups. Cell-labeling staining showed that the stromal cells migrated across the gap in the control and low adhesive groups, but there was no cell migration in the high adhesive group at two weeks.

CONCLUSION

A high fibrinogen concentration in a fibrin patch or glue may impede early cell migration.

LEVEL OF EVIDENCE

Not applicable because this study was a laboratory study.

Early active mobilization after primary repair of the flexor pollicis longus tendon

BACKGROUND

There have been few studies regarding primary flexor tendon repair of the thumb following early active mobilization, whereas there have been multiple such studies of the finger. This study examined the outcomes of patients who underwent early active mobilization after primary repair of the flexor pollicis longus tendon.

METHODS

This study was a retrospective case series. Between 1993 and 2019, 17 thumbs of 17 consecutive patients with complete flexor pollicis longus tendon lacerations were treated using the Yoshizu #1 technique, followed by early active mobilization. The mean time between injury and primary flexor tendon repair was 2 days. Two thumbs had zone T1 injuries and 15 had zone T2 injuries. Mobilization of the thumb began on the first postoperative day with a combination of active extension and passive and active flexion. The mean follow-up period was 8 months. The percentage of total active motion of the thumb was regarded as the sum of the active motion of the two joints, divided by 140°. Functional outcomes were graded in accordance with the Strickland criteria.

RESULTS

Three repair ruptures occurred in thumbs treated by inexperienced surgeons. Excluding tendon ruptures, the mean percentage of total active motion of the thumb was 83%. The mean active flexion of the interphalangeal and metacarpophalangeal joints was 62° and 64°. The mean extension deficit was 8.8° at the interphalangeal joint and 7.5° at the metacarpophalangeal joint. According to Strickland's criteria, repairs to eight thumbs were ranked excellent, three were good, one was fair, and five were poor.

CONCLUSIONS

Our results are not inferior to the findings of previous reports regarding early postoperative mobilization after primary flexor pollicis longus tendon repair, in terms of the acquisition of active thumb motion. Poor outcomes result from repair rupture and increased extension deficits of the interphalangeal and metacarpophalangeal joints.

Patient outcomes and costs after isolated flexor tendon repairs of the hand

BACKGROUND

Acute flexor tendon injuries are challenging injuries for patients, surgeons, and therapists alike. There is ongoing debate about the optimal timing and amount of therapy after these injuries.

PURPOSE

We sought to investigate the relationship between hand therapy utilization and reoperation rates after flexor tendon repair and quantify reoperation rates and costs associated with flexor tendon repair. We hypothesize there will be an inverse relationship between the number of hand therapy visits and later reoperation rates and a positive correlation between reoperation rates and total cost of care.

STUDY DESIGN

A retrospective cohort study of patients undergoing primary flexor tendon repair was pursued.

METHODS

A commercially available database was utilized to access insurance claims data for 20.9 million patients in the US from 2007 to 2015. Patients undergoing primary flexor tendon repair were included and followed for one year. Patients with fractures, vascular injuries, or digit replantation were excluded. We studied post-operative rehabilitation utilization, reoperation rates, and costs. Chi-Square tests and multivariable logistic regressions were used to assess the relationship between therapy utilization and reoperation rates and costs.

RESULTS

The one-year reoperation rate was 11.4 percent at a median time of 100.0 days amongst 1,129 patients undergoing primary tendon repair. In multivariable analysis, age between 30 and 59, male sex, and utilization of over 21 therapy sessions were associated with increased odds of reoperation. Mean insurance reimbursement one year following primary flexor repair was $14,533 per patient but $27,870 if patients went on to reoperation.

CONCLUSION

Continued therapy utilization after primary flexor tendon repair is an independent predictor of reoperation need. These findings may help surgeons counsel patients who require a large number of visits after flexor tendon repair on when to revisit surgical options.

Nanoparticle-coated sutures providing sustained growth factor delivery to improve the healing strength of injured tendons

Tendon injuries are common diseases. The healing capacity of tendon is limited due to its special composition of extra-cellular matrix and hypocellularity and hypovascularity. The purpose of this study was to evaluate the effectiveness of nanoparticle-coated sutures carrying growth factors for accelerating tendon repair. A variety of experimental methods had been used to investigate the characteristics and therapeutic effects of the modified sutures. Nanoparticles could adhere uniformly to the surface of the suture through polydopamine. Even sutured in the tendon, most of nanoparticles were still remained on the surface of suture, and the loaded proteins could spread into the tendon tissues. In vivo study, the ultimate strength of repaired tendons treated with bFGF and VEGFA-releasing sutures was significantly greater than the tendons repaired with control sutures at multiple time-points, whether in the chicken model of flexor tendon injury or the rat model of Achilles tendon injury. At week 6, the adhesion score in the bFGF and VEGFA-releasing suture group was significantly lower than those of the control suture group. Tendon gliding excursion was significantly longer in the bFGF and VEGFA-releasing suture group than that in the control bare sutures. Work of digital flexion was significantly decreased in the bFGF and VEGFA-releasing suture group. In a word, we developed a platform for local and continuous delivery of growth factors based on the nanoparticle-coated sutures, which could effectively deliver growth factors to tissues and control the release of growth factors. This growth factors delivery system is an attractive therapeutic tool to repair injured tendons. STATEMENT OF SIGNIFICANCE: Tendon rupture is a common clinical injury, due to the special character of the tendon with mainly extra cellular matrix and hypocellularity and hypovascularity, the healing capacity of the injured tendon is limited. In this study, nanoparticle-coated surgical sutures carrying growth factors were prepared to accelerate tendon repair. After treatment, bFGF and VEGFA loaded nanoparticle-coated sutures can significantly enhance tendon healing, and significantly improve tendon gliding function and effectively inhibit the formation of adhesion. Moreover, these nanoparticle-coated sutures have good biocompatibility and no obvious tissue reaction, which provides more guarantee for further clinical application. This is an attractive and promising approach that uses surgical suture as a growth factor delivery tool to repair tendon injury, which can simplify the treatment. And this kind of bioactive sutures may be applied to other tissue repair, such as muscle, nerve, intestinal canal, blood vessel, skin, and so on.

Lubricin as a tool for controlling adhesion in vivo and ex vivo

The ability to prevent or minimize the accumulation of unwanted biological materials on implantable medical devices is important in maintaining the long-term function of implants. To address this issue, there has been a focus on materials, both biological and synthetic, that have the potential to prevent device fouling. In this review, we introduce a glycoprotein called lubricin and report on its emergence as an effective antifouling coating material. We outline the versatility of lubricin coatings on different surfaces, describe the physical properties of its monolayer structures, and highlight its antifouling properties in improving implant compatibility as well as its use in treatment of ocular diseases and arthritis. This review further describes synthetic polymers mimicking the lubricin structure and function. We also discuss the potential future use of lubricin and its synthetic mimetics as antiadhesive biomaterials for therapeutic applications.

A novel titanium implant surface modification by plasma electrolytic oxidation (PEO) preventing tendon adhesion

Titanium is one of the most commonly used materials for implants in trauma applications due to its low density, high corrosion resistance and biocompatibility. Nevertheless, there is still a need for improved surface modifications of Titanium, in order to change surface properties such as wettability, antibacterial properties or tissue attachment. In this study, different novel plasma electrolytic oxidation (PEO) modifications have been investigated for tendon adhesion to implants commonly used in hand surgery. Titanium samples with four different PEO modifications were prepared by varying the electrolyte composition and analyzed with regards to their surface properties. Unmodified titanium blanks and Dotize® coating served as controls. Samples were examined using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), contact angle measuring system and analyzed for their biocompatibility and hemocompatibility (according to DIN ISO 10993-5 and 10,993-4). Finally, tendon adhesion of these specific surfaces were investigated by pull-off tests. Our findings show that surface thickness of PEO modifications was about 12-20 μm and had porous morphology. One modification demonstrated hydrophilic behavior accompanied by good biocompatibility without showing cytotoxic properties. Furthermore, no hemolytic effect and no significant influence on hemocompatibility were observed. Pull-off tests revealed a significant reduction of tendon adhesion by 64.3% (35.7% residual adhesion), compared to unmodified titanium (100%). In summary, the novel PEO-based ceramic-like porous modification for titanium surfaces might be considered a good candidate for orthopedic applications supporting a more efficient recovery.