Flexor Tendon Reconstruction

Diagnosis and treatment of flexor tendon injuries of the hand: what the radiologist needs to know

This article reviews the diagnosis and treatment of flexor tendon injuries of the hand highlighting flexor tendon anatomy, important pre-operative imaging findings, surgical options, and post-operative complications. Imaging plays a key role in guiding treatment of these difficult to manage injuries. Thus, it is important for radiologists to have a sound understanding of factors important in treatment decision-making. In the pre-operative setting, accurately identifying the location of the torn proximal tendon stump in subacute and chronic injuries helps dictate whether the patient is a candidate for a primary flexor tendon repair or may require a tendon reconstruction to restore function. In the post-operative setting, the status of the repair and presence of surrounding adhesions help dictate if and when the patient will require subsequent surgery and whether that surgery will be a tenolysis, revision repair, reconstruction, or fusion.

Alternate Graft Options for Staged Flexor Tendon Reconstruction: A Cadaveric Study of Hamstring Autografts Compared to Conventional Autografts

PURPOSE

To compare the semitendinosus and gracilis tendon lengths and diameters to the palmaris longus, plantaris, flexor digitorum profundus, and flexor pollicis longus (FPL) tendons in a cadaveric model to evaluate the feasibility of hamstring autograft use for staged flexor tendon reconstruction.

METHODS

Fifteen fresh cadavers were evaluated for surgical incisions about the knee, forearm, and hand. All flexor digitorum profundus (FDP), FPL, palmaris longus, plantaris, semitendinosus, and gracilis tendons were harvested from each specimen. Diameter and length were recorded and means with SDs were calculated. The mean diameters of the gracilis and semitendinosus were compared to the mean diameters of the FDP and FPL tendons. The hamstring tendon lengths were then compared in terms of percentage of the palmaris longus and plantaris tendon lengths.

RESULTS

The gracilis (18.0 cm) and semitendinosus (19.9 cm) means were notably longer than the palmaris longus (16.0 cm) and shorter than the plantaris (30.0 cm). The average gracilis tendon diameter (3.8 mm) was smaller than the flexor tendon diameters except for the little finger FDP (3.8 mm). The semitendinosus tendon diameter (4.8 mm) was larger than all flexor tendons with the exception of the middle finger FDP (4.6 mm). Average gracilis and semitendinosus tendon diameters were 3.7 mm and 4.5 mm in males, and 3.8 mm and 4.8 mm in females.

CONCLUSIONS

This study showed the gracilis tendon to have adequate length and diameter for potential autograft use in staged flexor tendon reconstruction in all digits but the little finger. The semitendinosus is larger in diameter than the native flexor tendons, making it a poor autograft option in cases with an intact pulley system.

CLINICAL RELEVANCE

Common tendon autograft options for flexor tendon reconstruction are variably present, and the use of gracilis and semitendinosus autograft present potential graft options.

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.

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.

Use of Silicone Tubes as Antiadhesion Devices in a Modified Two-Stage Flexor Tendon Reconstruction in Zone II: A Retrospective Study

PURPOSE

This study aimed to assess the outcome of a modified two-stage flexor tendon reconstruction using silicone tubes as antiadhesion devices while performing simultaneous tendon grafting.

METHODS

From April 2008 to October 2019, 16 patients (21 fingers) with zone II flexor tendon injuries, who sustained failed tendon repair or neglected tendon laceration, were treated by a modified two-stage flexor tendon reconstruction. The first stage of treatment comprised flexor tendon reconstruction with interposition of silicone tubes to minimize fibrosis and adhesion around the tendon graft; the second stage of treatment comprised silicone tube removal under local anesthesia.

RESULTS

The patient median age was 38 (range, 22-65) years. After a median follow-up period of 14 (range, 12-84) months, the median total active motion (TAM) of fingers was 220° (range, 150-250°). Excellent and good TAM ratings were identified in 71.4%, 76.2%, and 76.2% according to the Strickland, modified Strickland, and American Society for Surgery of the Hand (ASSH) evaluation systems, respectively. At follow-up, complications included superficial infections in two fingers of one patient whose silicone tube was removed 4 weeks postoperatively. The most common complication was a flexion deformity of the proximal interphalangeal joint (four fingers) and/or distal interphalangeal joint (nine fingers). The rate of failed reconstruction was higher in patients with preoperative stiffness and infection.

CONCLUSIONS

Silicone tubes are suitable antiadhesion devices, and the modified two-stage flexor tendon reconstruction technique is an alternative procedure with a shorter rehabilitation period for complicated flexor tendon injury, compared with current popular reconstructions. Preoperative stiffness and postoperative infection may compromise the final clinical outcome.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Comparing the outcomes of fingertip-to-palm and fingertip-to-forearm two-stage flexor tendon reconstruction for isolated flexor digitorum profundus tendon injuries

Flexor tendon injuries of the hand have devastating consequences when primary tendon repair fails or left untreated in the first place. Flexor tendon reconstruction is a substantial treatment option to obtain functional digit. In this study, we aimed to compare the functional outcomes and technical feasibility of fingertip-to-palm and fingertip-to-forearm tendon reconstruction methods. Thirty-five patients were divided into two groups according to the proximal attachment site of the free tendon grafts. Group I consisted of 18 patients whose tendon grafts were placed from fingertip-to-palm (zone III). Group II consisted of 17 patients whose tendon grafts were placed from fingertip-to-forearm (zone V). The mean of 39.6 months (range, 6-52 months) of follow-up with complete clinical data were obtained for all the cases. The mean length of the tendon grafts used in group I and group II was 9.7 ± 1.4 cm and 15.9 ± 1.2 cm, respectively. Significantly shorter tendon grafts were needed in group I (p < 0.001). Both mean DASH score and mean Michigan score were significantly improved postoperatively in both groups (p = 0.0001, p = 0.0001), but there was no significant difference between two groups based on postoperative DASH score (p = 0.112) and Michigan score (p = 0.151). No statistically significant difference was observed between two groups in terms of Strickland's scores (p = 0.868). This study demonstrates that comparable results can be obtained with fingertip-to-palm and fingertip-to-forearm staged tendon reconstructions. Fingertip-to-palm tendon reconstruction seems to be more advantageous when multiple flexor tendon injuries aimed to be reconstructed, in which requirement of tendon graft can be fulfilled with less donor site morbidity.Abbreviations: DASH: disabilities of the arm, shoulder and hand.

Design and In Vivo Testing of Novel Single-Stage Tendon Graft Using Polyurethane Nanocomposite Polymer for Tendon Reconstruction

Severe trauma, failure of prior surgical repair, delayed presentation and excessive scarring around the flexor tendon bed often necessitate a two-stage surgical reconstruction, where a silicone spacer is used in the first stage to recreate the fibro-osseous tunnel through which the tendon graft can glide in the second stage. This staged procedure involves great commitment on the part of both patient and surgeon, over the course of several months, involving a prolonged period of rehabilitation that can be quite disruptive to the patient's life and work. Reducing this from a two-stage into a single-stage procedure, therefore, has the potential to reduce rehabilitation time and cost, expedite return to work, and improve outcomes. To address this, we developed polyurethane (PU) nanocomposite, as an engineered tendon sheath, for treatment of delayed flexor tendon division as a single-stage procedure. The clinically conformant tubular grafts were tested for their efficacy in the peroneus tertius tendon of 6 Mule sheep for 3 months. Semi-quantitative histological assessment was carried out by analysing four descriptive layers: tendon, tendon/polymer sheath interface, polymer sheath, and polymer sheath/surrounding tissue. Four (out of 6) of the implanted PU nanocomposites showed moderate to substantial healing of the injured tendons, with minimal adhesion after repair, ensuring good gliding movement. No statistical differences were observed in tendon repair based on intra-regional variation in the explanted grafts, indicating homogeneity in tendon repair. Overall, the PU nanocomposite bears morphological stability and functionality for tendon repair, in single-stage surgical reconstruction, demonstrating promising evidence for clinical translation.

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.

Update on the Basic Science Concepts and Applications of Adipose-Derived Stem Cells in Hand and Craniofacial Surgery

SUMMARY

Adipose-derived stem cell therapy offers plastic surgeons a novel treatment alternative for conditions with few therapeutic options. Adipose-derived stem cells are a promising treatment because of their broad differentiation potential, capacity for self-renewal, and ease of isolation. Over the past decade, plastic surgeons have attempted to harness adipose-derived stem cells' unique cellular characteristics to improve the survival of traditional fat grafting procedures, a process known as cell-assisted lipotransfer. However, the full implications of cell-assisted lipotransfer in clinical practice remain incompletely understood, stressing the urgent need to assess the scientific evidence supporting adipose-derived stem cell-based interventions. Furthermore, with the strict regulatory climate surrounding tissue explantation therapies, reviewing the safety and efficacy of these treatments will clarify their regulatory viability moving forward. In this report, the authors provide a comprehensive, up-to-date appraisal of best evidence-based practices supporting adipose-derived stem cell-derived therapies, highlighting the known mechanisms behind current clinical applications in tissue engineering and regenerative medicine specific to plastic and reconstructive surgery. The authors outline best practices for the harvest and isolation of adipose-derived stem cells and discuss why procedure standardization will elucidate the scientific bases for their broad use. Finally, the authors discuss challenges posed by U.S. Food and Drug Administration oversight of these cell-based therapies and examine the role of adipose-derived stem cell-based applications in the future of plastic surgery.

Cellular Technologies in Traumatology: From Cells to Tissue Engineering

Injuries and degenerative changes of tendons are common damages of the musculoskeletal system. Due to its hypovascular character the tendon has a limited natural ability to recover. For typical surgical treatment, the tendon integrity is restored, but in most cases, there occurs formation of the connective tissue scar resulting in structural and mechanical functionality disruption. The insufficient effectiveness of traditional therapy methods requires the search for alternative ways to restore damaged tendon tissues. This article discusses new effective methods for improving the treatment that base on the use of cellular technologies among which one of the main directions is mesenchymal stem cell application. Due to mesenchymal stem cells, there is a shift from pro-fibrotic and pro-inflammatory reactions of cells to pro-regenerative ones. Stem cells being multipotent and having among other things tenogenic potential are considered a promising material for repairing damaged tendons. The article also describes the sources of progenitor tendon cells including the tendon bundles and pericytes the main markers of which are Scx and Mkx that are proteins of the transcription factor superfamily, and Tnmd that is transmembrane glycoprotein.

The growth factors that not only enhance the proliferative activity of mesenchymal stem cells but also promote in vitro tenogenic genes expression as well as the collagen Itype production what is necessary for tendon formation are considered. Along with growth factors, the morphogenetic protein BMP14 is presented, this protein increases themesenchymal stem cell proliferation and contributes directed tenogenic differentiation of these cells, suppressing their adipogenic and chondrogenic potentials.

In recent years, mesenchymal stem cells have been used both separately and in combination with various growth factors and different three-dimensional structures providing the interaction with all of the cell types.

The issues of the latest 3D-bioprinting technology allowing to make tissue-like structures for replacement damaged tissues and organs are discussed. 3D-bioprinting technology is known to allow acting exact spatio-temporal control of the distribution of cells, growth factors, small molecules, drugs and biologically active substances. 

Ultrasonographic assessment in vivo of the excursion and tension of flexor digitorum profundus tendon on different rehabilitation protocols after tendon repair

STUDY DESIGN

Interpretive description study.

PURPOSE

In management of patients with flexion tendon injuries, passive, control active and active motion protocols were proposed after repair to minimize tendon adhesion. The purpose of this study was to compare the excursion distance and the tension of Flexor Digitorum Profundus (FDP) during simulated active and passive motion using ultrasonography techniques using normal subjects.

METHODS

Ultrasonographic assessment of FDP tendon of the middle finger was performed at the wrist level on 20 healthy college students using 3 types of treatment protocols: modified Kleinert protocol, modified Duran protocol, and active finger flexion protocol. The excursion distance was measured following the musculotendinous junction of FDP using the B mode ultrasound system. The elasticity of FDP tendon was measured using the shear wave elastography technique. The excursion distance and the elasticity value were compared among 3 protocols using one-way ANOVA analysis.

RESULTS

Twelve male and 8 female students with mean age of 22.6 ± 1.8 years were invited to join the study. The excursion distance of FDP was 21.82 ± 3.77 mm using the active finger flexion protocol, 8.59 ± 2.59 mm using the modified Duran protocol, and 12.26 ± 2.71 mm using the modified Kleinert protocol. The elasticity was significantly higher in extension position when compared to passive flexion positions, but found lower than active flexion position.

DISCUSSION

The active finger protocol was found to require strongest tension of the tendon and with longest excursion. There was similar tension generated using both passive motion protocols. The modified Duran protocol appeared to create less excursion upon movements than the modified Kleinert approach using the objective ultrasonic evaluation. It is suggested that if the surgical repair was strong and without any complications, the active flexion protocol might work best to regain tension excursion. However, if there are complex problems involved, then the Kleinert approach or Duran approach would be chosen.

[Secondary reconstruction of flexor tendons]

The secondary reconstruction of flexor tendons is in most cases very demanding and tedious. The indications, selection of the correct surgical procedure, operative technique and further treatment have to be individually adjusted and are mostly very difficult. Due to the previous operations unpleasant surprises may occur intraoperatively, which must be recognized and treated by the surgeon. Nevertheless, a significant improvement of the function of the whole hand can be achieved for most patients, e.g. by a two-stage flexor tendon transplantation or other techniques described in this article.

Identification of the retrotalar pulley of the Flexor Hallucis Longus tendon

Functional Hallux Limitus is the expression of the gliding restraint of the Flexor Hallucis Longus (Fhl) tendon, resulting in several painful syndromes. This impingement is located along the tract of the Fhl tendon at the level of its retrotalar tunnel sealed posteriorly by a fibrous pulley. This pulley, although poorly anatomically characterized, has been arthroscopically proven that its presence or resection plays a pivotal clinical role in the biomechanics of the lower leg, being the main restraint to the physiological movement of the Fhl tendon. The aim of our study was to identify and characterize this anatomical structure. Eleven cadaveric lower legs were initially assessed by computer tomography (CT) imaging, subsequently plastinated, dissected and histologically evaluated by use of Mayer's and Hematoxylin stain. We have shown that the retrotalar pulley of the Fhl shares the same histological characteristics with the retinaculum of the long fibularis muscle and the retinaculum of flexor digitorum muscle, thus it constitutes a different entity than the adjacent formations.

Digital Pulley Reconstruction Using Pulley Allografts: A Comparison With Traditional Tendon-Based Techniques

BACKGROUND

The safety and feasibility of sterile, acellular pulley allografts in reconstruction has been previously demonstrated. Comparisons with tendon-based techniques for pulley reconstruction have not been reported. We hypothesized that the use of allograft pulleys would result in reduced procedural time and equivalent clinical outcomes as compared with traditional tendon-based reconstructive techniques.

METHODS

All cases of pulley reconstruction using either allograft pulleys or tendon-based pulley reconstruction between November 2013 and November 2015 were reviewed. Patients who underwent concomitant procedures were excluded. Patient demographics, comorbidities, operative details (tourniquet and total operative times, number of pulleys repaired), postoperative complications (surgical site infection, reoperation, stiffness, and persistent pain), disability of the arm, shoulder and hand scores, and follow-up data were recorded. A P value of <0.05 was considered significant.

RESULTS

Fifteen pulleys in 10 patients were reconstructed: 5 tendon-based and 5 with allograft. Average length of follow-up was 12.5 ± 2.9 months. There was no difference in patient demographic factors or comorbidities between groups. The most common indication for surgery was trauma. Four of 5 patients in the allograft group had multiple pulleys reconstructed versus 1 in the tendon-based group. One patient in the tendon-based group required reoperation versus 0 in the allograft group. Total operative and tourniquet times were significantly reduced in the allograft group (46 ± 5.5 vs 89 ± 12.9 minutes and 34 ± 6.8 vs 63 ± 5.3 minutes; P = 0.015 and 0.014). Postoperative disability of the arm, shoulder and hand scores were lower in the allograft group (56.8 vs 3.6, P = 0.11). There was no significant difference in postoperative range of motion between groups.

CONCLUSION

Pulley reconstruction with allograft is an efficient, technically feasible, reconstructive technique that adheres to the principle of replacing like with like, while eliminating donor site morbidity. Overall operative and tourniquet times were significantly shorter using allograft pulleys for pulley reconstruction.

Clinical Characteristics Associated with the Prognosis of One-Stage Grafting for Flexor Digitorum Profundus Reconstruction in Zones I and II

BACKGROUND

The authors aimed to identify clinical characteristics related to the prognosis after one-stage grafting for flexor digitorum profundus reconstruction in zones I and II.

METHODS

A total of 401 patients who underwent one-stage flexor digitorum profundus reconstruction after injuries in zones I and II, between January 1, 2006, and June 1, 2016, were included for analysis. The authors recorded the following clinical characteristics: duration from injury to reconstruction, graft type and length, handling (preservation or removal) of flexor digitorum superficialis, tenorrhaphy technique, and duration of postoperative immobilization.

RESULTS

There was no significant difference in age, sex, duration between injury and reconstruction, graft type, and handling of flexor digitorum superficialis between subjects who underwent successful reconstruction and those who did not. Univariate and multivariate analyses revealed that end-to-end tenorrhaphy, immediate controlled motion, and immobilization for less than 2 weeks all independently were related to improved final outcomes. Grafting within zones I and II contributed to increased incidence of failure. In a subgroup having an injury-reconstruction duration of less than 2 weeks, the authors observed that grafting from zone III to zones I and II tended to result in better outcomes compared with grafting from zone III to the flexor digitorum profundus insertion. This, however, was not statistically significant (p = 0.11).

CONCLUSIONS

The authors recommend end-to-end tenorrhaphy, reducing immobilization to less than 2 weeks, and avoiding grafting within zones I and II. In addition, further studies are still needed to clarify the optimal length of grafting.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.