Biomaterials for the Treatment of Tendon Injury

BACKGROUND: Most tendon injuries are occurring from a gradual wearing and tearing of the tendon tissues from overuse. Such injuries are usually seen in sports, exercising, or daily activities that involve a high mechanical load and weight bearing. However, owing to the lack of both cellularity and blood vessels in tendons, the process of tendon repair is slow and inefficient. Although various conservative (non-surgical) and surgical management options are conducted by the clinicians, a gold standard of these approaches does not exist. In this regard, the treatment of tendon injuries is challenging. METHODS: Here, we describe the recent advances of biomaterial-based approaches for the treatment of injured tendons. RESULTS: Regenerative medicine is an emerging multidisciplinary research that specializes in the repair of damaged tendon tissues through the delivery of regenerative factors by biomaterials. CONCLUSION: Although current biomaterial-based treatment strategies have shown their potential for tendon healing, future research and clinical applications should focused on finding the optimum combinations of regenerative factors with ideal biomaterials for the repair of tendons.

Dynamic biomechanical observations of healing process of tendon repaired by five different suture techniques / 国际生物医学工程杂志

Objective To observe the biomechanieal properties of tendons repaired by five suture techniques in different stage of healing process.Methods After establishing the zone Ⅱ FDP transection model in 2nd,3rd,4th too of both feet in female fowls,the ruptured tendons were repaired with Modified Kessler ( M K ),Kessler plus running ( K +R ),double-strand Kessler ( DK ),double loop (DT) and modified double loop (MT) methods,respectively.Passive and active mobilizations were applied on the 3rd day and 21st day postoperatively.Animals were executed postoperatively,on the 14th,21st and 35th days,respectively and both feet were harvested for biomechanical test.Results Anatomical findings included: The breakage incidence of K+R group was smaller than that of MK group.The excellent and good results of K+R and DK groups were higher compared with that of MK group.Biomechanical results showed: The MK group had the poorest biomechanical results in every stage of tendon healing (P＜0.05) except that the results from MK group on the 35th showed no statistical difference compared with that of MT and DT in extreme load;K+R group exbited the greatest extreme load and tensile strength (P＜0.05);Biomechanical test results from all groups showed significant differences on different testing point: 35th day＞21st day＞14th day(P＜0.05 );No significant differences were found in all groups between the immediate postoperative results onlst day and that from 14th day.ConclusionDuring the recovery of tendon,biomechanical properties returned to the immediate postoperative level on the 14th day and increased along with time.K+R group shows the superiority to the other methods in biomechanical properties as well as low breaking incidence ratein every stage of tendon healing.Kessler plus running is an effective method with high strength against breakage and great resistance to adhesion formation.

Biomechanical analysis in the early period of flexor tendon healing after decimeter wave therapy / 中华物理医学与康复杂志

Objective To investigate the biomechanicai characteristics of flexor profundus tendons repaired after decimeter wave therapy, and to observe the effect of decimeter wave therapy on early active mobilization. Methods A total of 56 Leghorn chickens were randomly divided into a therapy group and a control group with 28 chickens in each. The 3rd and 4th toes of their left feet were employed for the establishment of a tendon injury model. The flexor profundus tendons were cut and repaired. Gypsum support was applied and fixed with an adhesive plaster after the operation. The operated sites on toes Ⅲ and Ⅳ were exposed. The external fixation was removed 3 weeks later and the chickens were left free to move. Decimeter wave therapy ( frequency 915 MHz, power 8 Watts) was ap-plied for 10 minutes once daily on the left foot of each chicken in the therapy group from day 1 until 3 weeks after the operation. Sham decimeter wave therapy was applied to chickens in the control group. Four chickens from each group were randomly selected at the 1st, 7th, 10th, 14th, 18th, 21st and 28th days for biomechanical analysis. Biome-chanical parameters including tensile strength of rupture (Pmax), elongation ratio at rupture (δimax) and the tensile adhesion strength of the rupture zone (W0>) were observed at each time point. Results At the 7th, 10th, 14th, 18th, 21st and 28th day after the operation, the differences in Pmax, δmax and W0 between the therapy and control groups were statistically significant. The results of the therapy group were better than those of the control group. Conclusions Local decimeter wave therapy after flexor tendon repair can promote intrinsic healing and reduce ex-trinsic healing. The speed and quality of healing are improved. The elasticity and tenacity of the injured tendons are enhanced. Therefore decimeter wave therapy is helpful for early active mobilization training.

Effects of Hyperosmolar Dextrose Water on Healing of Injured Achilles Tendon in Rats

OBJECTIVE: To assess the effects of intratendinous injection of 12.5% dextrose water on healing of injured Achilles tendon in rat. METHOD: Quantification of hydroxyproline concentration in Achilles tendons of 21 Sprague-Dawley rats was performed to assess the concentration of collagen, and hematoxyline-eosin and immunochemistry staining was performed to analyse histopathology. RESULTS: There was no significant difference in collagen concentration between the three groups (p>0.05). Light microscopic examination showed irregular arrangement of coarse collagen fibers and decreased number of fibroblasts in sham treatment and dextrose injection group and showed more irregular arrangement of coarse collagen fibers in dextrose injection group than in sham treatment group. The immunochemical staining of sham treatment and dextrose injection group showed more increased immunoreactivity for type I and III collagen than control group, but the same as in sham treatment group and dextrose injection group. CONCLUSION: The increase of collagen concentration in injured Achilles tendon of rat treated with hyperosmolar dextrose was not found. This implies that clinical observation of collagen remodelling process may alter biomechanical property other than collagen concentration which should be further investigated.

The Healing Effect of Pulsed Ultrasound on Injured Achilles Tendon in Rats

OBJECTIVE: To explore the healing effect of low intensity pulsed ultrasound with three different timing of intervention after tenotomy of Achilles tendon in rats. METHOD: One hundred and thirty-two male rats were divided into experimental and control groups. Both groups were classified according to treatment phase: treatment on inflammatory phase (group I), proliferative phase (group II), and maturation phase (group III). Each groups were divided into 2 subgroups according to tendon excision time: 1 day after 7 consecutive treatment on 3 different phases (I-A, II-A, and III-A) and 30 days after tenotomy (I-B, II-B, and III-B). Three MHz pulsed ultrasound was administered on right tendon for 4 mins at 0.5 W/cm2. The excised tendons of all groups were compared histologically and biochemically as control. RESULTS: The tendons of II-A experimental group revealed increased fibroblasts. The collagen fibers in the neo-tendon of II-B and III-B experimental groups had a tendency to be arrayed more regularly. On I-A group, the neo-tendon showed high immunoreactivity for type I and particularly type III collagen in cytoplasm of fibroblasts and collagen fibers. The imunoreactivity for type III collagen in the neo-tendon of II-A experimental group increased than control. The concentration of collagen of the neo-tendon was significantly increased on I-A and II-A experimental groups compared with control (p<0.05). Collagen concentration of the neo-tendon of II-B experimental group increased significantly compared with control and I-B and III-B experimental groups (p<0.05). CONCLUSION: These results suggest that low intensity pulsed ultrasound therapy on injured Achilles tendon may be of benefit such as increasing collagen synthesis in the early healing process, especially in proliferative phase.

A Comparative Study on Healing of Bone - Tendon Autograft and Bone - Tendon - Bone Autograft Using Patellar Tendon in Rabbits / 대한정형외과학회잡지

The purpose of this study is to compare the biologic properties of tendon to hone healing and hone to hone healing in knee ligament reconstruction. The lateral 4mm of patellar tendon which was detached from its tihial insertion site either subperiostcally(group I) or with a bone block(group II) was implanted and fixed using pullout method to the proximal tihia. Ten rabbits were killed at each of four time periods (two, four, eight and twelve weeks after the implantation), and the histological and biomechanical characteristics of thc graft healing sites were evaluated. Serial histological analysis of tendon to hone healing group revealed organization of the healing site similar to normal tendon to hone attachment by twelve weeks, while hone to bone healing group demonstrated direct hony union by eight weeks. The tension failure test for the patellapatellar tendon graft - tihia complex revealed that group II had significantly higher values than group I at four and eight weeks. The findings ot this study demonstrated that bone to hone healing has more rapid process than tendon to hone healing, although no significant difference was noted once the healing has matured. We can suggest lhat the duration and extent of postoperative protection of the knee for pntients who had a reconstruction of a ligament using hone - lendon autograft should be longer and higher than lor patients who had a reconstruction using hone - tendon hone autogralf.

An experimental study of healing of the partially severed flexor tendon in chickens

There is a lack of clinical and experimental studies of the treatment of incompletely transected tendons. The controversy concerning the source of flexor tendon nutrients is of important clinical concern in healing of the injured tendon; thus, the flexor tendon blood supply has cited as a reason for using specific tendon suture techniques, and as a rationale for preserving the superficialis tendon and its vincula during tendon repair surgery. Our knowledge of the normal physiology of digital flexor tendons and the mechanism of their healing process is deficient. The aim of this study was to investigate the relative importance of the synovial fluid and the blood supply respectively for the healing of partially severed flexor tendons. We observed the sequential histological and vascular changes which occur in healing of the partial lacerations in the dorsal and plantar aspects of the tendons. We observed the vascularities of the two partially severed tendon groups after injection of microfil and india ink through the femoral artery. In the healing process there was no sequential histological difference between the dorsal and the plantar severed tendons. The vascularity patterns of the healing tendons were significantly increased and the hypervascularity of dorsal severed tendons was greater than that of plantar severed tendons. Partially severed tendons were completely healed without surgical repair with dense collagen fibers without adhesion in most cases. We concluded from this study that the blood vessels appeared to play a significant role in the healing of the severed flexor tendons. An intact synovial environment did not seem to be required for healing of the severed tendon. It is not necessary to surgically repair the partially severed tendon for prevention of rupture and adhesion.