Tendon Repair Site Research Articles

Use of Biodegradeable Temporizing Matrix Dermal Template for Reconstruction of Upper Extremity Soft Tissue Defects with Associated Tendon Injury.

In cases of complex upper extremity soft tissue defects with exposed bone or tendon, the surgeon needs to consider both restoration of stable soft tissue coverage and functional outcomes, which requires early motion and a wound bed suitable for tendon gliding. Often, local, regional, or free flaps are necessary; however, good outcomes have also been reported after staged reconstruction with a dermal template and split-thickness skin grafting. To our knowledge, staged reconstruction with a dermal template has not been described for soft tissue defects with an associated underlying tendon injury requiring tenorrhaphy. We have previously reported our experience with a synthetic dermal template [Novosorb BTM (Biodegradable Temporizing Matrix), Polynovo North America LLC. Carlsbad, Calif.] for the reconstruction of complex upper extremity defects with exposed tendon and showed that it consistently and reliably integrates even when these patients were treated with an early, active therapy protocol. As a result of these findings, we hypothesized that BTM could potentially be used over a tendon repair site without compromising functional outcomes. Here, we report on clinical outcomes for two patients with upper extremity injury where BTM was applied directly over a tendon repair or transfer site and resulted in stable soft tissue coverage with excellent tendon gliding. These early results show that this approach might be considered as an alternative to autologous tissue reconstruction in these patients and could reduce donor site morbidity associated with flap harvest.

Encircling tendon repair site with collagen sheet in flexor zone 2: retrospective study

BackgroundPeritendinous adhesion is the most common complication of tendon repairs in the hand and often requires surgical intervention, resulting in increased labor loss and increased treatment costs. Many agents used to reduce tendon adhesion in animal models, however these agents have not entered clinical use. This study is the first-ever clinical study that evaluates encircling tendon repair site with collagen sheet as an anti-adhesion barrier.MethodsBetween December 2014 and January 2020, 156 patients included in this study, with clean cut isolated flexor digitorum profundus (FDP) tendon injury in flexor tendon zone 2. All tendons repaired with modified double Kessler technique. In 76 patients, tendon repair site encircled with collagen sheet. 80 patients were randomly selected from our clinical records and functional results are compared with Strickland’s total active motion grading system.ResultsThe mean total range of motion was 79% in the control group and 81% in the collagen sheet group, and there was no statistically significant difference between the two groups (Z: − 1.393, p = 0.164). In the control group, very good and good repair according to Strikland classification was 65/80 (81%). In the collagen sheet group, it was 62/76 (82%), respectively. There was statistically significant difference between 5 FDP TAM measurements between collagen sheet and control group (t(35) = 0.29, p = 0.016, p < 0.05). The mean TAM of the 5 FDP tendons in the collagen sheet group: 83.8 (SD: 8.2) in the and 76.1 (SD: 9.5) in the control group.ConclusionsFor the first time in the literature, functional results of Zone 2 flexor tendon repair using collagen sheets in patients with clean cut tendon injuries reported. However, there were no statistical difference about total active motion between control and collagen sheet group, 5th FDS tendon repairs encircled with collagen sheets had better outcomes. Prospective studies in patient groups with high adhesion risk are recommended.

4 A Quantitative Image Analysis Study of Modified Kessler Extensor Repair

Abstract Aim The aims of this study were to compare and measure the amount of 4.0 Prolene suture material at the tendon repair site with 2 types of knot placement in a modified Kessler technique, as placement of suture knot can impact extensor tendon healing. Method Thirty-two extensor tendons of 2 fresh frozen cadaveric hands were divided and repaired using the modified Kessler technique with either intratendinous or extratendinous knot placement of a 4.0 Prolene suture. Tendon repairs were sectioned, and cross-sectional photographs were analysed using quantitative image analysis. Results Comparison of percentage change in tendon dimension surface area showed no significant difference (p = 0.4750) between intratendinous and extratendinous knot placement to demonstrate consistency of repair. Quantitative image analysis revealed suture material occupied a significantly (p = 0.0103) larger percentage of tendon cross sectional area in intratendinous than extratendinous knot placement. In both groups this represented &amp;lt;10% of the total cross-sectional area of the tendon at the repair site (7.49% vs 2.92%). There was no significant relation between digit, tendon or repair zone and percentage of repair zone occupied by suture material. Conclusions Intratendinous knot placement occupies a larger proportion of tendon cross sectional area than extratendinous knot placement, though this is still comparatively small when a 4’0 monofilament suture is used.

The effect of augmenting suture material with magnesium and platelet-rich plasma on the in vitro adhesion and proliferation potential of subacromial bursa-derived progenitor cells

Connective tissue subacromial bursa-derived progenitor cells (SBDCs) have been suggested as a potent biologic augment to promote healing of the repaired rotator cuff tendon. Maximizing the amount of retained progenitor cells at the tendon repair site is essential for ensuring an optimal healing environment, warranting a search for proadhesive and proliferative adjuvants. The purpose was to evaluate the effect of magnesium (Mg), platelet-rich plasma (PRP), and a combination of both adjuvants on the invitro cellular adhesion and proliferation potential of SBDCs on suture material commonly used in rotator cuff surgery. SBDCs were isolated from subacromial bursa samples harvested during rotator cuff repair and cultured in growth media. Commercially available collagen-coated nonabsorbable flat-braided suture was cut into 1-inch pieces, placed into 48-well culture dishes, and sterilized under ultraviolet light. Either a one-time dose of 5 mM sterile Mg, 0.2 mL of PRP, or a combination of both adjuvants was added, while a group without treatment served as a negative control. Cellular proliferation and adhesion assays on suture material were performed for each treatment condition. Augmenting the suture with Mg resulted in a significantly increased cellular adhesion (total number of attached cells) of SBDCs compared to PRP alone (31,527±19,884 vs. 13,619±8808; P<.001), no treatment (31,527±19,884 vs. 21,643±8194; P=.016), and combination of both adjuvants (31,527±19,884 vs. 17,121±11,935; P<.001). Further, augmentation with Mg achieved a significant increase in cellular proliferation (absorbance) of SBDCs on suture material when compared to the PRP (0.516±0.207 vs. 0.424±0.131; P=.001) and no treatment (0.516±0.207 vs. 0.383±0.094; P<.001) group. The combination of Mg and PRP showed a significantly higher proliferation potential compared to PRP alone (0.512±0.194 vs. 0.424±0.131; P=.001) and no treatment (0.512±0.194 vs. 0.383±0.094; P<.001). There were no significant differences in the remaining intergroup comparisons (P>.05, respectively). Augmenting suture material with Mg resulted in a significantly increased cellular adhesion of SBDCs compared to untreated suture material, as well as augmentation with PRP alone or a combination of both adjuvants. Further, Mg with or without PRP augmentation achieved a significant increase in the cellular proliferation of SBDCs on suture material compared to untreated sutures and augmentation with PRP alone. Application of Mg may be a clinically feasible approach to optimizing the use of SBDCs as a biological augment in rotator cuff repair, while combined augmentation with PRP may harness the full potential for optimized tissue recovery due to the high concentration of PRP-derived growth factors.

Can pirfenidone prevent tendon adhesions? An experimental study in rats.

In this experimental study, we aimed to investigate the effectiveness of oral pirfenidone (PFD) treatment on preventing tendon adhesion and tendon healing in rats. A total of 21 rats were assigned into three groups including seven rats in each group. In Group 1 (sham group), no surgical procedure was performed. In Group 2 (control group), tendon repair was performed following right achillotomy. In Group 3 (treatment group), the rats also underwent tendon repair after right achillotomy. Additionally, 30 mg/kg of oral PFD was initiated from the postoperative Day 1 and administered via gavage for 28 days. At the end of the study, tendon healing and fibrosis levels in the tendon repair site were compared macroscopically, histopathologically, and immunohistochemically among the groups. Macroscopically, moderate and severe adhesions were observed in four and three rats, respectively in the control group, while no adhesion was found in four rats and filmy adhesions were observed in three rats in the treatment group (p<0.01). Microscopically, there was moderate adhesions in three rats and severe adhesions in four rats in the control group, while three rats had no adhesions and four rats had slight adhesions in the treatment group (p<0.01). Microscopically, tendon healing was good in six rats and fair in one rat in the control group, while five rats showed excellent tendon healing and two rats showed good tendon healing in the treatment group (p<0.01). Immunohistochemically, expressions of collagen I (p<0.01), collagen III (p<0.001), vascular endothelial growth factor (VEGF) (p<0.001), and proliferating cell nuclear antigen (PCNA) (p<0.001) significantly decreased in the treatment group compared to the control group. Our study results indicated that PFD decreased collagen synthesis and prevented the formation of peritendinous adhesion in rats; however, it did not impair tendon healing.

Micro- and nano-environment dual-modulated anti-tendon adhesion barrier membranes

Despite promise in preventing peritendinous adhesion, electrospun membranes face many challenges related to their complex fabrication process, untargeted/uncontrolled drug delivery and consequently low therapeutical effect. Here, a micro-and nano-environment dual-modulated barrier membrane (MNBM) with on-demand gene delivery capability is presented. Our MNBM is developed by first preparing extracellular signal-regulated kinase-2 (ERK2) siRNA-loaded gelatin methacryloyl (GelMA) nanogels via facile nano-emulsification technique, then incorporating these nanogels into poly-L-lactic acid (PLLA) fibers via simple blending electrospinning. The GelMA nanogels offer a nano-niche for ERK2-siRNA encapsulation and allow for a nano-environment controlled siRNA release by readily tuning the GelMA concentrations during nano-emulsification, while the resultant MNBM can mediate a micro-environment controlled siRNA delivery in response to the matrix metalloproteinase-2 (MMP-2) enriched micro-environment at the tendon repair site. Such MNBM can not only biologically orchestrate fibroblast behaviors by silencing the target gene expression, but also physically shield the tendon from extrinsic cell/tissue invasion. This study provides a proof-of-concept of anti-adhesion barrier membrane as an intelligent gene delivery system to offer a spatiotemporal and biophysical dual control over tendon recovery according to disease state and ensure long-term therapeutic efficacy. We envision such MNBM represents a promising therapeutic platform with great efficacy to achieve adhesion-free tendon repair.

Injection of Leukocyte-Poor Platelet-Rich Plasma for Moderate-to-Large Rotator Cuff Tears Does Not Improve Clinical Outcomes but Reduces Retear Rates and Fatty Infiltration: A Prospective, Single-Blinded Randomized Study

To determine whether leukocyte-poor platelet-rich plasma (Lp-PRP) reduced retear rates, reduced fatty infiltration, and improved functional outcomes in patients with degenerative moderate-to-large rotator cuff tears. This was a randomized controlled study at a single center. A consecutive series of 104 patients with moderate-to-large rotator cuff tears was enrolled and randomly allocated to a control group (double-row suture-bridge arthroscopic rotator cuff repair alone, n= 52) and a study group (double-row suture-bridge repair followed by 3 Lp-PRP injections at the tendon repair site during surgery, at days 7 and 14 after surgery, n= 52). All patients were followed up for 27.2 months (range 24-36 months), with University of California at Los Angeles (UCLA) shoulder rating scale, the Constant score, and a visual analog scale (VAS) evaluated respectively. The integrity and fatty infiltration of repaired tissue were assessed by magnetic resonance imaging using the Sugaya classification and Goutallier grade classification at 24 months after surgery. Statistical analysis was performed based on the t test, χ2 test, and the Kendall tau-b correlation coefficient. Four patients refused follow-up, and 11 patients had incomplete data. Eventually, a total of 89 patients were available for 24 months follow-up. The mean UCLA score increased from 14.80 ± 2.53 to 29.37 ± 2.06 in control group and from 13.74 ± 3.30 to 30.14 ± 2.32 in study group (P= .103). The mean Constant score increased from 46.56 ± 5.90 to 86.83 ± 4.94 in control group and from 44.37 ± 7.92 to 88.80 ± 4.92 in study group (P= .063). The VAS score decreased from 3.22 ± 1.24 to 0.97 ± 1.12 in control group and in 3.49 ± 1.52 to 1.16 ± 0.99 in study group (P= .41). All differences in UCLA score, Constant score, and VAS between pre- and postoperation achieved minimal clinically important differences proposed for arthroscopic rotator cuff repair. Of the 89 patients, 76 had magnetic resonance imaging performed at 24 months after surgery. The retear rate was 17.6% in study group, which was lower than that in control group (38.1%, P= .049). In addition, the Goutallier grade was found to be significant difference between groups postoperatively (Kendall tau-b -0.24, P= .03) but no significant difference preoperatively (Kendall tau-b -0.18, P= .11). There were no complications in the patients. Our procedures involving repeated injections of Lp-PRP during surgery and at days 7 and 14, as described in this study, have positive effects on reducing retear rate and promoting Goutallier grade in patients following arthroscopic rotator cuff repair and could also provide substantial clinical outcomes that reach the minimal clinically important difference for surgical treatment. However, given the numbers available for analysis, it did not promote better clinical results when compared with the control group. II, randomized controlled study.

Effectiveness of Sodium Hyaluronate and ADCON-T/N for the Prevention of Adhesions in Hand Flexor Tendon Surgery: A Systematic Review and Meta-Analysis

A common complication after digital flexor tendon repair in the hand is postoperative adhesions that can cause loss of motion and compromise hand function. The aim of this review of relevant published literature was to assess the effectiveness of locally administered sodium hyaluronate or ADCON-T/N for the prevention of adhesions after hand flexor tendon repair. A literature search was conducted in June 2020 in multiple databases for randomized controlled trials . Our primary outcome was measurement of active finger motion. Follow-up was defined as short-term (< 12 weeks), mid-term (12 weeks to 6 months) and long-term (> 6 months). Mean differences (MD) and standardized mean differences (SMD) of total active motion (TAM) of the interphalangeal joints (IPJs) and active motion of the IPJs separately were calculated where results were meta-analyzed. Six randomized controlled trials were included. For ADCON-T/N, no benefits were detected for TAM of the IPJs (MD 1.71 [-21.54, 24.96]) or active motion of the IPJs separately (proximal: MD 4.77 [-4.47, 14]; distal: MD 1.17 [-10.33, 12.66]) in the short-/mid-term. The mid-term benefit in TAM of sodium hyaluronate over standard care (placebo/no treatment) did not reach statistical significance (SMD 0.31 [0, 0.63]); however, a subgroup comparison of repeated administration of sodium hyaluronate versus standard care was both statistically and clinically significant (SMD 0.55 [0.11, 0.98]). Repeated administration of sodium hyaluronate at the tendon repair site may be effective in improving postoperative active finger motion after primary hand flexor tendon repair in the mid-term. Therapeutic II.

Flexor tendon repair using a reinforced tubular, medicated electrospun construct.

A reinforced tubular, medicated electrospun construct was developed for deep flexor tendon repair. This construct combines mechanical strength with the release of anti-inflammatory and anti-adhesion drugs. In this study, the reinforced construct was evaluated using a rabbit model. It was compared to its components (a tubular, medicated electrospun polymer without reinforcement and a tubular braid as such) on the one hand to a modified Kessler suture as a control group. Forty New Zealand rabbits were randomly divided into two groups. Surgery was performed in the second and fourth deep flexor tendons of one hind paw of the rabbits in the two groups using four repair techniques. Biomechanical tensile testing and macroscopic and histological evaluations were performed at 3 and 8 weeks postoperatively. A two-way analysis of variance with pairwise comparisons revealed that the three experimental surgical techniques (a reinforced tubular medicated electrospun construct, tubular-medicated construct, and tubular braid as such) showed similar strength as that of a modified Kessler suture repair, which was characterized by a mean load at ultimate failure of 19.85 N (standard deviation [SD] 5.29 N) at 3 weeks and 18.15 N (SD 8.01 N) at 8 weeks. Macroscopically, a significantly different adhesion pattern was observed at the suture knots, either centrally or peripherally, depending on the technique. Histologically, a qualitative assessment showed good to excellent repair at the tendon repair site, irrespective of the applied technique. This study demonstrates that mechanical and biological repair strategies for flexor tendon repair can be successfully combined.

Effect of hyperdry amniotic membrane in preventing tendon adhesion in a rabbit model

BackgroundNo anti-adhesive materials are currently in clinical use for orthopaedic surgery. We developed a hyperdry amniotic membrane (HD-AM) for easy storage and transplantation as amniotic membrane. The purpose of this study was to examine the application of HD-AM to reduce peritendinous adhesions without impairing tendon healing. MethodsWe randomly divided 3 digits (2nd, 3rd, and 4th digits) from each rabbit into three groups: a tendon repair group; a tendon repair with HD-AM group (HD-AM group); and a control group (cast only). The effects of HD-AM on peritendinous adhesions and tendon healing were examined using microscopic, histological, and mechanical analyses in a rabbit flexor digitorum profundus tendon model. ResultsAdhesions on macroscopic evaluation of the tendon repair site were significantly smaller in the HD-AM group than in the tendon repair group. Little adhesion formation or foreign body reactions were seen by on histologic evaluation in the HD-AM group. Range of motion following tendon repair was significantly better in the HD-AM group than in the tendon repair group. Maximal tensile strength required to pull the tendon from the site of adhesion was significantly smaller in the HD-AM group than in the tendon repair group. As for tendon repair site, no significant difference was seen between the tendon repair and HD-AM groups. ConclusionsHD-AM prevented peritendinous adhesion macroscopically, pathologically, and mechanically without impairing the sutured tendon. HD-AM has already been clinically applied in neurosurgery, ophthalmology, and otolaryngology, and clinical application as an anti-adhesive materials may be achieved in the future.

The effect of the platelet-rich plasma and ozone therapy on tendon-to-bone healing in the rabbit rotator cuff repair model

BackgroundThe aim of this study is to histologically and biomechanically investigate the effects of local PRP and ozone therapy (O2O3) on tendon-to-bone healing in a rabbit model of the supraspinatus tendon tear.MethodsFour groups were formed to have seven rabbits in each group: repair, R; repair + PRP, RP; repair + ozone, RO; and repair + PRP + ozone, RPO. The supraspinatus tendon was detached by sharp dissection from the footprint and an acute tear pattern was created. Thereafter, tendon repair was performed with the transosseous technique. In the RP group, PRP, and in the RPO group, PRP + O2O3 mixture was injected to the tendon repair site. In the RO group, O2O3 gas mixture was injected into subacromial space three times a week for a total of 4 weeks. The study was ended at postoperative 6th week.ResultsWhen compared with the R group, a statistically significant increase was observed in the biomechanical strength of the RP and RPO groups. The highest increase in biomechanical strength was detected in the RPO group. The histology of the RO and RPO groups showed better collagen fiber continuity and orientation than the R and RP groups.ConclusionsThe results obtained from this study show that the ozonized PRP can be used as biological support to increase tendon-to-bone healing. However, these results need to be supported by clinical studies.

Flexor tendon repair with amniotic membrane.

Flexor tendon adhesion to tissues is one of the most frequent complications reported after flexor tendon repair. The human amniotic membrane (HAM) was used to wrap the tendon repair site to decrease fibrotic response and tendon adhesion. A total of 19 patients with flexor tendon injuries were subjected to surgical repair. The repair site was wrapped with human amniotic membrane (HAM) in nine cases. The remaining ten cases served as controls as no HAM wrap was used. The clinical outcome was assessed by pain, range of motion, and pinch strength. The healing of repair was evaluated with high-frequency ultrasound; the biologic response was assessed with two inflammatory mediators, i.e., interleukin-6 and TGF-beta-1. HAM wrap cases recorded less pain, higher total active range of motion, and better tendon glide on ultrasonography at follow-up (6-18months). The levels of serum inflammatory biologic markers decreased in majority of HAM cases whereas they increased in controls at two to six weeks post-operatively. No infection/immune rejection phenomenon was seen in HAM wrap cases. HAM wrap around the tendon repair site resulted in quicker function and qualitatively better tendon healing on ultrasound, with a decrease of the biologic response.

A biomechanical screening tool for élite athletes after ACL surgery

Many poor outcomes after arthroscopic rotator cuff (RC) repair relate to failure of tendon healing. The purposes of this study were to provide a better understanding of the magnetic resonance arthrography (MRA) characteristics of the RC tendon repair site after arthroscopic RC repair and to examine how these findings influence patient-reported outcome measures (PROMs) and the presence of persistent symptoms.We reviewed 48 shoulders (13 female and 35 male patients; average age, 53.8 years) at a minimum of 6 months (average, 11.4 months) after arthroscopic RC repair (average tear size, 2.2 cm). All patients completed PROMs and underwent MRA assessment. Detailed analysis of the RC repair site was undertaken, with findings correlated with clinical outcomes and PROMs.The average preoperative American Shoulder and Elbow Surgeons (ASES) score of 39.5 improved to 92.8 (P < .001). All but 6 patients (87.5%) had increased signal intensity of the involved tendon, with interstitial splits and/or delamination in 65.6%. These changes had no effect on PROMs or patient satisfaction. Significant partial-thickness tears (>50%) were observed in 7 patients (14.6%), with no effect on outcomes (average ASES score of 95.2 and satisfaction score of 9). There were 2 recurrent full-thickness tears (4.2%), and 4 patients (8.3%) had a failure in continuity. The average ASES score in these 6 cases of failure was 76 (P < .001).Structural abnormalities on MRA are common after RC repair but do not always result in clinical failure. However, our results suggest that an ASES score of less than 80 may be useful when considering postoperative imaging, especially in a patient with ongoing pain more than 6 months after surgery.

Arthroscopic rotator cuff repair: magnetic resonance arthrogram assessment of tendon healing

Many poor outcomes after arthroscopic rotator cuff (RC) repair relate to failure of tendon healing. The purposes of this study were to provide a better understanding of the magnetic resonance arthrography (MRA) characteristics of the RC tendon repair site after arthroscopic RC repair and to examine how these findings influence patient-reported outcome measures (PROMs) and the presence of persistent symptoms. We reviewed 48 shoulders (13 female and 35 male patients; average age, 53.8 years) at a minimum of 6 months (average, 11.4 months) after arthroscopic RC repair (average tear size, 2.2 cm). All patients completed PROMs and underwent MRA assessment. Detailed analysis of the RC repair site was undertaken, with findings correlated with clinical outcomes and PROMs. The average preoperative American Shoulder and Elbow Surgeons (ASES) score of 39.5 improved to 92.8 (P < .001). All but 6 patients (87.5%) had increased signal intensity of the involved tendon, with interstitial splits and/or delamination in 65.6%. These changes had no effect on PROMs or patient satisfaction. Significant partial-thickness tears (>50%) were observed in 7 patients (14.6%), with no effect on outcomes (average ASES score of 95.2 and satisfaction score of 9). There were 2 recurrent full-thickness tears (4.2%), and 4 patients (8.3%) had a failure in continuity. The average ASES score in these 6 cases of failurewas 76 (P < .001). Structural abnormalities on MRA are common after RC repairbut do not always result in clinical failure. However, our results suggest that an ASES score of less than 80 may be useful when considering postoperative imaging, especially in a patient with ongoing pain more than 6 months after surgery.

Rotator Cuff Repair: Patch the Shoulder

Rotator cuff tears are a common problem in our growing and aging population. Because of this, rotator cuff repair is consistently one of the most frequently performed operations by orthopaedic surgeons every year. Successful outcomes have been directly correlated to a successful repair to the tuberosity; however, healing rates have varied greatly depending on tear size, tear type, and tear chronicity. Despite advances in techniques and repair technology, healing rates have remained relatively stable.Improving the biology at the site of a rotator cuff repair has been proposed as a way of increasing healing rates. A recent bio-inductive patch has been introduced to improve the vascularity and collagen formation at the site of tendon repair. The implant is made from type I bovine collagen that is highly porous. It is nonstructural and does not provide any tensile strength. The patch improves collagen formation at the site of a repair, thus decreasing strain on the repaired tendon.Limited clinical trials involving the collagen patch have shown healing rates from 89% to 96% in small sample sizes. The patch has been successfully and safely applied in tear sizes ranging from partial thickness tears to massive tears, as well as primary and revision repair settings. To date, no adverse clinical reactions to the patch have been observed; however, no randomized clinical trials have been performed, and the patch is a significantly increased cost to the procedure.

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.

Photochemical Tissue Bonding Technique for Improving Healing of Hand Tendon Injury

We utilized a novel approach of combined photochemical tissue bonding (PTB) and human amniotic membrane (HAM) to improve hand tendon repair and also evaluated its efficacy. Subei chickens underwent surgical transection of the flexor digitorum profundus tendons and repair by (1) SR (standard Kessler suture; n = 24; 6-0 prolene) and (2) HAM/PTB (n = 24), where a section of HAM was stained with 0.1% Rose Bengal, wrapped around the ruptured tendon and bonded with 532 nm light (0.5 W/cm2, 200 J/cm2). Total active motion, gross appearance, extent of adhesion formation, biochemical properties, and inflammatory cells of the repaired tendon were evaluated on days 3, 7, 14, and 28 postoperatively. PTB strongly bonded HAM with flexor digitorum profundus tendon surface. No significant difference was observed between the tensile properties of either group on all postoperative time points. The joint activities and the adhesion formation levels were significantly better in the HAM/PTB group compared with those in the SR group on day 14. Histological examination revealed drastically reduced number of inflammatory cells in the HAM/PTB group than in the SR group on days 7 and 14 after surgery. These findings revealed that PTB sealing of HAM around the tendon repair site provided considerable benefits for hand tendon repair by eliminating technical difficulties and obvious contraindications. Thus, this novel procedure has considerable benefits in repairing hand tendon damage.

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

III.

Migration of Mesenchymal Stem Cells of Bursal Tissue after Rotator Cuff Repair in Rats.

Purpose The purpose of this study is to verify migration of mesenchymal stem cells of bursal tissue into the healing site after rotator cuff repair in rats. Methods Fischer rats and green fluorescent protein (GFP)-transgenic rats were used. Bursal tissue from GFP rats was isolated and transplanted into tendon repair sites in Fischer rats. We examined the histology of the rotator cuff and the proportion of GFP-positive cells in the repaired rotator cuff 1, 3, and 6 weeks after surgery. Results Cell migration was observed during the third and sixth week after surgery. We also found mesenchymal stem cells and formed bursal cluster patterns in the repaired rotator cuff tendons. Conclusion Mesenchymal stem cells migrated from bursal tissue and infiltrated the repaired rotator cuff tendons. Clinical Relevance Mesenchymal stem cells from bursal tissue can contribute to the healing progress of the repaired rotator cuff.

The effects of bi-functional anti-adhesion scaffolds on flexor tendon healing in a rabbit model.

Progressive tendon adhesion is a major challenge in flexor tendon repair. The authors developed a bifunctional anti-adhesion scaffold and hypothesized that its application would reduce adhesion formation and deliver mesenchymal stem cells (MSCs) to enhance tendon healing. The scaffold was fabricated by an electrospinning machine before surface modification. The flexor tendons of 29 New Zealand rabbits underwent surgical repair and randomized to control, scaffold and scaffold loaded with MSC group. At 3 and 8 weeks post-surgery, range of motion (ROM), biomechanical properties, and histology were examined. There was no significant increase in ROM and biomechanical properties between the three groups. The histology showed successful delivery of MSCs but no significant difference in nuclear morphometry. This barrier delivers and retains MSCs within the tendon repair site. However, its sheet form and wrapping around the repair site may not be optimal for tendon healing. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2605-2614, 2018.