Sonographic study of repair, gapping and tendon bowstringing after primary flexor digitorum profundus repair in zone 2

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).

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

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

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.

Safety and efficacy of ultrasonography of tension after zone II flexor tendon repair: A randomized controlled trial

BACKGROUND

Primary flexor tendon repairs of lacerations in zone II of the hand are fraught with problems. Traditionally, exercise (active and passive), orthoses, and physical agents are common interventions for the rehabilitation of patients experiencing these issues. One area of focus in this field is how to safely utilize tension to lengthen gliding distance following zone II injury. Finding effective solutions in this area is a key priority for improving patient outcomes and quality of life.

PURPOSE

To identify the optimal immobilization position that meets safety standards for tension and is the most efficient, and consequently, to validate our clinical effectiveness.

STUDY DESIGN

A cross-sectional study was adopted for the first part of the research (Research 1). A prospective, parallel, 2-group, randomized trial was conducted with concealed allocation and single blinding in the second part of the research (Research 2).

METHODS

A total of 60 healthy adults were recruited to select the best-fit protective immobilization position in Research 1, which was confirmed by tendon tension (via Young's modulus) and excursion (via gliding distance). We then randomly assigned 45 patients after zone II flexor tendon repair into two groups in Research 2 to compare functional outcomes. The control group underwent the conventional modified Duran protocol with early passive motion, while the experimental group received the protocol (optimized by Research 1) with early active motion. Ultrasonography was used to measure the tension and excursion of the flexor tendons. The outcomes measured at 16 weeks post-repair included total active motion, strength, the Disabilities of the Arm, Shoulder and Hand, and Strickland scores.

RESULTS

Three participants were unable to participate in Research 2 due to medical issues and poor attendance. The investigation found that the safe tendon threshold was 345.09 ± 87.74 kPa for partial active digital motion among the 60 participants. The optimal immobilization position requires the wrist to be neutral with a flexion angle of 30° at the metacarpophalangeal joint. The grip strengths (p = 0.012), ratio of grip strength (p = 0.015), the Disabilities of the Arm, Shoulder and Hand (p = 0.036), and total active motion (p = 0.023) differed significantly between the two groups.

CONCLUSIONS

Protective immobilization of the wrist in a neutral flexion position and with the metacarpophalangeal joint flexed at 30° can secure the repaired flexor tendon safely and efficiently. The effects of an early active motion ‎protocol may improve the grip strength and upper limb mobility of individuals after zone II flexor tendon repair.

CLINICAL TRIAL REGISTRATION

ChiCTR2000030592.

Flexor Tendon Repair Techniques: M-Tang Repair

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

Ultrasound evaluation of surgically repaired hand tendons during rehabilitation and its relation to clinical and functional assessment

Objectives

This study aimed to evaluate the contribution of musculoskeletal ultrasound to the follow-up of surgically repaired hand tendons during rehabilitation programs and correlate ultrasound findings with the clinical outcome.

Patients and methods

In the prospective observational study, 40 patients (29 males, 11 females; mean age: 27.4±10.7 years; range, 15 to 55 years) who presented with postoperative hand tendon repair between January 2019 and March 2020 were randomized into two groups: Group 1 included 15 subjects with 16 repaired flexor tendons, whereas Group 2 consisted of 25 subjects with repaired extensor tendons. Afterward, the assessment was performed at the four, eight, and 12 weeks of rehabilitation utilizing the total active motion of injured fingers, Visual Analog Scale (VAS), grip strength, ultrasound, and hand assessment tool (HAT).

Results

The study's findings revealed a substantial improvement in pain based on the evaluation of grip strength, total active motion, VAS, and the affected hand's HAT score in both groups (p<0.001). In both groups, ultrasonographic evaluation of healing tendons revealed considerable enhancement in margination, defect size, thickness, echogenicity, and vascularity. A positive correlation was detected between VAS and healing tendon margination as well as the HAT score and handgrip margination in Group 1.

Conclusion

High-frequency ultrasound is an easily accessible modality in the follow-up and evaluation of tendon healing after surgical repair and during a rehabilitation program.

Diagnostic Imaging of A2 Pulley Injuries: A Review of the Literature

Injury to the A2 pulley is caused by high eccentric forces on the flexor-tendon-pulley system. Accurate diagnosis is necessary to identify the most appropriate treatment options. This review summarizes the literature with respect to using ultrasound (US) to diagnose A2 pulley injuries, compares ultrasound to magnetic resonance imaging and computed tomography, and identifies current knowledge gaps. The results suggest that US should be used as the primary imaging modality given high accuracy, relatively low cost, ease of access, and dynamic imaging capabilities. Manual resistance is beneficial to accentuate bowstringing, but further research is needed to determine best positioning for evaluation.

Six-Strand Flexor Pollicis Longus Tendon Repairs With and Without Circumferential Sutures: A Multicenter Study

BACKGROUND

The purpose of this study is to assess outcomes in flexor pollicis longus tendon repairs with 6-strand core sutures with and without circumferential sutures.

METHODS

A 6-strand core suture technique with and without circumferential sutures was used. Thirty-three patients were summarized in the C group (circumferential group) and 16 patients in the NC group (non-circumferential group). After the surgery, the wrist was stabilized with a dorsal blocking splint and a controlled early active motion protocol was applied. At weeks 6, 13, and 26 data on demographics, type of injury, surgery, postoperative rehabilitation, complications such as re-rupture and the following outcome measurements were collected: range of motion and its recovery according to the Tang criteria, Kapandji score, thumb and hand strengths, Disabilities of the Arm, Shoulder and Hand score, and satisfaction.

RESULTS

There were no significant differences in range of motion and strength between the 2 treatment groups. In both groups, the outcome measurements increased over time and they expressed similar satisfaction with the surgical treatment. In 4 patients of the C group tendon repair ruptured and in 1 patient of the NC group.

CONCLUSIONS

Six-strand repair technique is an effective procedure to assure early active motion after flexor pollicis longus tendon injuries and good results can also be achieved by omitting the circumferential suture.

Mini-open surgical management of a type-2 jersey finger under WALANT with ultrasound assistance: A case report about a new technique

We describe an innovative mini-open technique for reinsertion of the flexor digitorum profundus tendon under Wide Awake Local Anesthesia No Tourniquet (WALANT) with ultrasound assistance. Ultrasound-aided detection at the surgeon's practice is used to plan the surgical tendon repair procedure so that tendon reinsertion can be performed with the smallest incision possible. Passage of the tendon through the digital sheath was accomplished with the help of a compressive tendon guide to avoid a surgical approach. Reinsertion of the tendon under WALANT monitoring enables intraoperative validation of repair tension and physiological restitution of tendon glide within the digital sheath. Postoperative ultrasonographic examination at the surgeon's practice is an occasion to further patient education begun intraoperatively under WALANT.

Flexor pollicis longus zone 2 tendon repair under WALANT with ultrasound assistance

A feature of the flexor pollicis longus tendon injury is the frequency of palmar retraction so that a wrist approach is needed for retrieval of the proximal stump. We are reporting on our first outpatient zone T2 flexor pollicis longus tendon repair under WALANT with ultrasound guidance. In the event of zone T2 flexor pollicis rupture, ultrasound location of tendon extremities is used to plan surgical WALANT strategy and to guide the injection of lidocaine with epinephrine whilst limiting the injected volume to what is strictly necessary.

Flexor digitorum profundus with or without flexor digitorum superficialis tendon repair in acute Zone 2B injuries

A total of 53 patients with complete cuts of two flexor tendons in Zone 2B treated over a 9-year period was reviewed. Twenty-three patients (28 fingers) had only flexor digitorum profundus repair, while 30 patients (36 fingers) had both flexor digitorum profundus and flexor digitorum superficialis repairs, with a mean follow-up of 21 months (range 12-84). The decision to repair the flexor digitorum superficialis was made according to intraoperative judgement of ease of repair and gliding of the flexor digitorum profundus tendon. Two groups of patients showed no significant differences in total range of active or passive digital motion and power grip percentage to the contralateral hand. However, the values of power grip were statistically superior in the patients with both tendons repaired. The patients after flexor digitorum profundus-only repairs showed significantly greater but still mild flexion contracture (mean 20 °) of the operated digits. The Tang gradings were the same with 89% good and excellent rates in both groups. The conclusion is that although repair of both flexor digitorum profundus and flexor digitorum superficialis tendons is slightly more preferable based on increased grip strength, the repair of the flexor digitorum superficialis together with flexor digitorum profundus is not mandatory. Whether or not to repair flexor digitorum superficialis is an intraoperative decision based on the ease of gliding of the repaired tendon(s).Level of evidence: III.

Pulley Release and Reconstruction With Acellular Dermal Matrix After Zone 2 Flexor Tendon Injury

Zone 2 flexor tendon repair has been historically associated with poor outcomes, mainly due to stiffness. In an effort to minimize adhesions, accommodate flexor digitorum profundus and flexor digitorum superficialis bulk, and prevent bowstringing, we have developed a novel approach to flexor tendon repair that relies on aggressive flexor tendon pulley release and pulley reconstruction with acellular dermal matrix. This technique leverages the antiadhesive properties and high tensile strength of acellular dermal matrix to maximize gliding and prevent bowstringing. Here we describe the details of our technique and illustrate a case where this technique was employed.

Effects of a Q Suture Technique on Resistance to Gap Formation and Tensile Strength of Repaired Tendons: An Ex Vivo Mechanical Study

PURPOSE

The repair of digital flexor tendons following laceration should aim to prevent gapping at the repair site and restore the tensile strength of the tendons to facilitate postoperative movement. We present here a simple Q suture and test its effects on gap formation and tensile strength of the repaired tendons.

METHODS

Sixty porcine tendons were repaired with 3 2-strand sutures (Kessler, Kessler plus 2Q, and Kessler plus running sutures) and 3 4-strand sutures (double Kessler, double Kessler plus 2Q, and double Kessler plus running sutures). The specimens were subjected to a cyclic loading. At each cycle, the number of tendons that initiated gapping or formed a 2-mm gap at the repair site was determined. After the cyclic load testing, the gap distance between tendon ends and the ultimate strength of the repaired tendons was measured.

RESULTS

In both 2-strand and 4-strand tendon repairs, augmentation by insertion of the 2Q sutures reduced the number of tendons that showed 2-mm gaps ends during loading. Compared with the single Kessler and Kessler plus running sutures, Kessler plus 2Q suture significantly increased the ultimate strength of the tendon repair. Compared with the double Kessler and double Kessler plus running sutures, double Kessler plus 2Q suture significantly decreased the gap distance at the repair site after cyclic loading.

CONCLUSIONS

The Q suture technique effectively enhances the resistance to gap formation of 2-strand and 4-stand tendon repair. It also improves the tensile strength of 2-strand Kessler repairs.

CLINICAL RELEVANCE

The Q suture is a simple technique that can resist gap formation and strengthen the tensile strength of the repaired tendons in the laboratory setting.

Outcomes of 200 digital flexor tendon repairs using updated protocols and 30 repairs using an old protocol: experience over 7 years

We reviewed outcomes of 230 flexor tendon repairs in 27 thumbs and 203 fingers in Zone 1 and 2 over 7 years. In 2013, we used a 2-strand modified Kessler method followed by passive motion exercise in repairing flexor digitorum profundus tendon injuries in Zone 2 in 30 fingers; 24 fingers were followed, five (26%) had repair ruptures. Between 2014 and 2017, we used a 4- or 6-strand method to repair 111 flexor digitorum profundus tendons in Zone 2, followed by true early active motion. Two had repair ruptures. Among 101 fingers followed over 6 months, two fingers had tenolysis and 87 (87%) good or excellent outcomes. In 2018 to 2019, we used a 6-strand method to repair 42 flexor digitorum profundus tendons in Zone 2 with out-of-splint early active motion. None had repair ruptures or tenolysis. From 2014 to 2019, 27 flexor pollicis longus tendons were repaired in Zone 1 or 2, and 20 fingers had end-to-end flexor digitorum profundus repairs in Zone 1; none had repair ruptures or tenolysis. We conclude that a strong repair and true active motion are necessary for best outcomes of flexor tendon repairs in the thumb and fingers, and out-of-splint true active motion is safe.

Effect of different positions of splinting on flexor tendon relaxation: a cadaver study

We performed a cadaver study to evaluate how six different static heat-moulded splints affect flexor tendon relaxation. Each splint positioned the wrist and metacarpophalangeal (MCP) joints in different positions. We evaluated the tendon relaxation in 12 fresh adult cadaver forearms by measuring the flexor tendon displacement between two solid markers for each splint. The wrist position ranged from 30° flexion to 45° extension and the MCP joints from 30° to 60° flexion. For each splint, tendon relaxation was achieved relative to the neutral reference position. Tendon relaxation was greatest when the MCP joints were positioned in 60° flexion. We also noted the persistence of tendon relaxation when the wrist was positioned in extension (30° or 45°) as long as MCP joint flexion was maintained (30° or 60°). We conclude that the wrist extension with the MCP joints flexion may optimize tendon relaxation during immobilization after flexor tendon repairs.

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

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

Incidence of tenolysis and features of adhesions in the digital flexor tendons after multi-strand repair and early active motion

We report seven patients requiring tenolysis after primary or delayed primary flexor tendon repair and early active mobilization out of 148 fingers of 132 consecutive patients with Zone 1 or 2 injuries from 1993 to 2017. Three fingers had Zone 2A, two Zone 2B, and two Zone 2C injuries. Two fingers underwent tenolysis at Week 4 or 6 after repair because of suspected repair rupture. The other five fingers had tenolysis 12 weeks after repair. Adhesions were moderately dense between the flexor digitorum superficialis and profundus tendons or with the pulleys. According to the Strickland and Tang criteria, the outcomes were excellent in one finger, good in four, fair in one, and poor in one. Fingers requiring tenolysis after early active motion were 5% of the 148 fingers so treated. Indications for tenolysis were to achieve a full range of active motion in the patients rated good or improvement of range of active motion of the patients rated poor or fair. Not all of our patients with poor or fair outcomes wanted to have tenolysis. Level of evidence: IV.

Zone 2 flexor tendon repairs using a tensioned strong core suture, sparse peripheral stitches and early active motion: results in 60 fingers

We report the outcomes of zone 2 tendon repairs in 60 fingers using a strong core suture, sparse peripheral stitches and early active motion. From January 2014 to April 2016, we repaired 60 flexor digitorum profundus tendons with a tensioned 4-strand or 6-strand core suture and three to four peripheral stitches. The A2 or A4 pulleys were vented as necessary. Following early active flexion of the repaired tendons, no repairs ruptured and 52/60 (87%) fingers recovered to good or excellent function using the Tang criteria after follow-up of 8-33 months. We conclude that tensioned multi-strand strong core repairs only require sparse peripheral stitches and are safe for early active flexion. Standard peripheral sutures are not necessary. The core sutures should be properly tensioned to prevent gapping at tendon repair site and pulleys should be sufficiently vented to allow tendon motion. Level of evidence: IV.

Comparison of the strength of two multi-strand tendon repair configurations in a chicken model

We sought to investigate the strength of two multi-strand tendon repair configurations in a chicken model. Fifty-six chicken flexor tendons were repaired with one to two different four-strand configurations: 1) a four-strand repair consisting of a two-strand core modified Kessler suture with a circle loop repair and 2) a four-strand core Kessler suture repair with three separate peripheral suture points. The strength of the repaired tendons were measured 2, 3 and 4 weeks after the surgical repair and were analyzed statistically. The strength of the two repair methods was not statistically different 2 weeks after surgery. The tendons repaired with the four-strand core Kessler suture repair and three separate peripheral suture points were significantly stronger than those repaired with a two-strand core modified Kessler suture and a circle loop repair at 3 weeks (P = 0.033) and 4 weeks (P = 0.039). The four-strand repair with three separate peripheral suture points had greater strength than a two-strand repair with one circle loop suture based on an in vivo chicken flexor tendon model.