Auto‐crosslinked hyaluronic acid gel accelerates healing of rabbit flexor tendons in vivo

This study's purpose was to assess the in vivo effect of auto‐crosslinked hyaluronic acid (HA) gel, a natural HA derivative with increased viscosity and tissue residence time, on adhesions and healing of injured and surgically repaired rabbit digital flexor tendons. The second and third right deep digital flexor tendons from 48 rabbits (n = 96 tendons) were cut and repaired with a modified Kessler and running peripheral suture. Animals were randomized to two groups, receiving either HA gel or saline injected around both freshly repaired tendons. After 2, 3, 6, and 12 weeks, six rabbits in each group were euthanized. Tendon pull‐out force and breaking strength were measured as a value for adhesion formation and tendon healing, respectively. A histological assessment of adhesions and healing was related to the mechanical results. A significantly faster increase in breaking strength was found in HA gel‐treated compared to saline‐treated tendons; this coincided with a significantly accelerated tissue repair response after injury. No significant difference in adhesion formation was found between the two groups at any time. Our results indicate a significant acceleration of in vivo healing of tendons treated with HA gel. Adhesion formation was unaffected. These results could have important clinical value in promoting rehabilitation after tendon injury. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:408–415, 2009     

Effects of human amniotic fluid on peritendinous adhesion formation and tendon healing after flexor tendon surgery in rabbits

The effect of the topical application of human amniotic fluid (HAF) on peritendinous adhesion formation and tendon healing was investigated in 32 New Zealand adult rabbits. The long flexor tendons of the digits of each hind paw were completely divided and repaired with a modified Kessler technique. The rabbits were randomly divided into 4 experimental groups according to the type of repair used: sheath excision, sheath excision and local HAF application, sheath repair, and sheath repair and local HAF application. The extent of adhesions and the healing status of the tendons were macroscopically and histologically evaluated at 12 weeks. Tensile strength of the repaired tendons was measured biomechanically at 20 weeks. The least adhesion and the best healing were observed in tendons treated with sheath repair and HAF application. Tendons treated with HAF had significantly higher tensile load values. Topical application of HAF immediately after tenorrhaphy is significantly effective in preventing peritendinous adhesion formation without impairment of tendon healing in this rabbit model.     

GDF-5 deficiency in mice delays Achilles tendon healing.

The aim of this study was to examine the role of one of the growth/differentiation factors, GDF-5, in the process of tendon healing. Specifically, we tested the hypothesis that GDF-5 deficiency in mice would result in delayed Achilles tendon repair. Using histologic, biochemical, and ultrastructural analyses, we demonstrate that Achilles tendons from 8-week-old male GDF-5 -/- mice exhibit a short-term delay of 1-2 weeks in the healing process compared to phenotypically normal control littermates. Mutant animals took longer to achieve peak cell density, glycosaminoglycan content, and collagen content in the repair tissue, and the time course of changes in collagen fibril size was also delayed. Revascularization was delayed in the mutant mice by 1 week. GDF-5 deficient Achilles tendons also contained significantly more fat within the repair tissue at all time points examined, and was significantly weaker than control tissue at 5 weeks after surgery, but strength differences were no longer detectable by 12-weeks. Together, these data support the hypothesis that GDF-5 may play an important role in modulating tendon repair, and are consistent with previously posited roles for GDF-5 in cell recruitment, migration/adhesion, differentiation, proliferation, and angiogenesis.     

Revitalized and synovialized allograft for intrasynovial flexor tendon reconstruction in an in vivo canine model

This study was to test our hypothesis that flexor tendon reconstruction with an allograft revitalized with bone marrow stromal cells (BMSCs) and synovialized with carbodiimide derivatized autologous synovial fluid (cd‐SYN) would result in better digit functional restoration than the conventional allograft tendon. A total of 32 flexor digital profundus tendons from the second and fifth digit of 16 dogs were created a repair failure model first. Then, failed‐repaired tendons were reconstructed with either a revitalized‐synovialized allograft tendon or a clinical standard autograft tendon (control group). The allograft tendon was seeded with autologous BMSCs in multiple slits and the graft surface was coated with cd‐SYN. A 6 weeks after tendon reconstruction, the digits were harvested and evaluated for digit function, adhesion status, tendon gliding resistance, attachment strength, cell viability, and histologic factors. The allograft group had significantly improved digit function compared with the control group through decreased work of flexion, increased digit range of motion under 2‐Newton force, and less adhesion score (p < .05). However, the distal attachment‐site strength and stiffness in the allograft tendon were significantly weaker than the autografts (p < .05). No significant difference was found for gliding resistance. Histologically, allograft tendons coated with allograft had smoother surfaces and showed tendon‐to‐bone and tendon‐to‐tendon incorporation. Viable BMSCs were found in the tendon slits 6 weeks after the graft. In conclusion, cellular lubricant‐based modification of allograft tendons improved digit function and reduced the adhesions compared with autograft for flexor tendon reconstruction. However, improvement of graft‐to‐host tendon healing is still challenging. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2218–2227, 2018.

     

Pulsed ultrasound treatment accelerates the repair of Achilles tendon rupture in rats.

A rat tenotomy model was used to investigate the effect of combined conservative management and pulsed ultrasound (PUS) on the repair of tenotomized Achilles tendon. Hemitenotomy of right medial Achilles tendon was performed in 48 rats without suture, and patella tenotomy was performed to mimic immobilization and limb disuse of an injured limb. PUS and sham PUS were applied to the healing wound for the treatment group and control group for 5 min, 3 times per week for 2 or 4 weeks, respectively. Tensile tests showed that the ultimate tensile strength (UTS) and stiffness of the repaired tendon in the treatment group at 2 weeks reached 48.92+/-8.39% and 62.48+/-32.46% of the contralateral normal tendon strength, which were significantly higher than those of the control group (UTS, 30.36+/-15.46%; stiffness, 33.90+/-17.59; p<0.05). At 4 weeks, UTS increased to 77.09+/-15.31% and stiffness to 92.48+/-31.12% in the treatment group, significantly higher than those in the control group (UTS, 54.33+/-18.40%, p<0.01; stiffness, 65.02+/-25.48%, p<0.05). Light microscopy revealed more regular, denser, and better aligned collagen fibers in the healing scar of the PUS-treated healing tendons. The findings suggested that PUS were able to accelerate the healing of the ruptured tendons.     

Mechanical Load and BMP Signaling During Tendon Repair: A Role for Follistatin?

Healing of the rat Achilles tendon is sensitive to mechanical loading, and the callus strength is reduced by 3/4 after 14 days, if loading is prevented. Exogenous GDFs stimulate tendon healing. This response is influenced by loading: without loading, cartilage and bone formation is initiated. This implies BMP signaling is crucial during tendon healing and influenced by mechanical loading. We therefore asked if mechanical loading influences the gene expression of the BMP signaling system in intact and healing tendons, and how the BMP signaling system changes during healing. The genes were four BMPs (OP-1/BMP-7, GDF-5/CDMP-1/BMP-14, GDF-6/CDMP-2/BMP-13, and GDF-7/CDMP-3/BMP-12), two receptors (BMPR1b and BMPR2), and the antagonists follistatin and noggin. The Achilles tendon was transected in rats and left to heal. Half of the rats had one Achilles tendon unloaded by injection of Botox in the calf muscles. Ten tendons were analyzed before transection and for each of four time points. All genes except noggin were expressed at all time points, but followed different patterns during healing. Loading strongly decreased the expression of follistatin, which could lead to increased signaling. The BMP system appears involved in tendon maintenance and healing, and may respond to mechanical loading.     

异体肌腱移植术后早期形态学观察和生物力学研究

目的 通过观察新西兰大白兔异体肌腱移植术后早期的组织学形态并检测其生物力学性质,评估异体肌腱移植后是否适合进行早期功能锻炼.方法 取新西兰大白兔30只分成自体肌腱移植和异体肌腱移植两组,分别于术后3 d、1周、2周、4周、8周时取肌腱进行大体观察,HE染色后行组织学切片观察,生物力学检测包括肌腱抗拉强度、拉伸至2 mm间隙时的强度、肌腱滑动时的阻力.方果 大体观察和组织学切片显示,异体肌腱移植后愈合较自体肌腱移植开始晚、持续时间长,术后2周时肌腱与周围组织尚未形成致密的粘连,术后4周肌腱与周围组织形成的粘连较致密.力学测试显示在肌腱愈合的过程中其力学强度略低.术后3 d和1周时,肌腱滑动的阻力小于肌腱的抗拉强度;2周时肌腱的强度有所下降,肌腱滑动的阻力增加;术后4周时肌腱与周围组织形成较致密的粘连,其滑动的摩擦力大于肌腱的强度;术后8周时肌腱与周围组织形成致密粘连.方论 异体肌腱移植术后1周内肌腱的强度大于肌腱滑动的阻力,此时可以开始谨慎的早期功能锻炼.     

Effects of lubricant and autologous bone marrow stromal cell augmentation on immobilized flexor tendon repairs

The purpose of the study was to test a novel treatment that carbodiimide‐derivatized‐hyaluronic acid‐lubricin (cd‐HA‐lubricin) combined cell‐based therapy in an immobilized flexor tendon repair in a canine model. Seventy‐eight flexor tendons from 39 dogs were transected. One tendon was treated with cd‐HA‐lubricin plus an interpositional graft of 8 × 10⁵ BMSCs and GDF‐5. The other tendon was repaired without treatment. After 21 day of immobilization, 19 dogs were sacrificed; the remaining 20 dogs underwent a 21‐day rehabilitation protocol before euthanasia. The work of flexion, tendon gliding resistance, and adhesion score in treated tendons were significantly less than the untreated tendons (p < 0.05). The failure strength of the untreated tendons was higher than the treated tendons at 21 and 42 days (p < 0.05). However, there is no significant difference in stiffness between two groups at day 42. Histologic analysis of treated tendons showed a smooth surface and viable transplanted cells 42 days after the repair, whereas untreated tendons showed severe adhesion formation around the repair site. The combination of lubricant and cell treatment resulted in significantly improved digit function, reduced adhesion formation. This novel treatment can address the unmet needs of patients who are unable to commence an early mobilization protocol after flexor tendon repair. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:154–160, 2016.     

The effects of a combination of hyaluronic and amniotic membrane on the formation of peritendinous adhesions after flexor tendon surgery in chickens

We have investigated the effects of the intra-operative application of a combination of hyaluronic acid and amniotic membrane on adhesions in the flexor tendons of a chicken model. We used 144 tendons which were partially divided and then repaired by a modified Kessler technique. There were four test groups: group 1, simple tendon repair, group 2, repair site wrapped with amniotic membrane, group 3, hyaluronic acid injected around the repair site, and group 4, repair site wrapped with amniotic membrane and hyaluronic acid injected within it. At three and six weeks, the extent of the adhesions and the healing of the tendon were evaluated macroscopically and histologically. The range of movement of the toe and tensile strength of the repaired tendons were measured at 20 weeks. The least adhesions were observed in group 4 but no significant difference was found in the healing of the tendons. Overall, the intra-operative application of a combination of hyaluronic acid and amniotic membrane appears to be effective in preventing adhesions of the flexor tendon.     

Oral ibuprofen: evaluation of its effect on peritendinous adhesions and the breaking strength of a tenorrhaphy

In a study of 21 primates, treatment with oral ibuprofen significantly reduced the force required for tendon gliding following flexor tendon injury in zone II. Tendons that were partially lacerated but not repaired required less force for tendon motion than those repaired. Ibuprofen also reduced the breaking strength of completely divided and repaired extensor tendons. The addition of a piece of chromic suture buried across the extensor tenorrhaphy site significantly increased the breaking strength of the repair in control and treated animals alike. These findings were observed at 4 and 6 weeks after tendon injury and repair. No adverse reactions to the medication were observed.     

Effect of absorbable polydioxanone flexor tendon repair and restricted active mobilization in a canine model.

We performed an experimental study to evaluate the mechanical and histologic healing process of flexor tendon repair using absorbable polydioxanone monofilament followed by active mobilization. Sixty-four canine flexor digitorum profundus tendons were repaired using polydioxanone monofilament or control braided polyester. Animals were evaluated 7, 14, 28, and 42 days after surgery with 12 day 0 control tendons. All repaired tendons healed without rupture or gap formation. Mechanically, all specimens had adequate tensile strength enabling active mobilization. The tendons that were repaired using braided polyester healed without initial tensile depression; however, the ultimate tensile strength values of polydioxanone specimens showed a significant decrease at day 14. Histologically, an inflammatory response was observed around the polydioxanone monofilament; this reaction increased from day 14 to day 42. However, the inflammatory response did not cause large adhesions or large tendon callus formation. This method of using absorbable suture material for tendon repair has the potential for use in the clinical setting.     

Biomechanical comparison of new Achilles tendon rupture repair technique the “Giftbox” versus the Krackow technique in New Zealand white rabbits: An experimental animal study

IntroductionTo compare the strength between the Achilles tendons repaired with the “Giftbox” and the Krackow techniques in New Zealand white rabbits post six weeks of tendon healing.Materials and MethodsEight rabbits were randomized into Giftbox and Krackow groups. Tenotomy was performed on the Achilles tendon of one side of the lower limb and repaired with the respective techniques. The contralateral limb served as control. Subjects were euthanized six weeks post-operative, and both repaired and control Achilles tendons were harvested for biomechanical tensile test.ResultsThe means of maximum load to rupture and tenacity in the Giftbox group (156.89 ± 38.49 N and 159.98 ± 39.25 gf/tex) were significantly different than Krackow's (103.55 ± 27.48 N and 104.91 ± 26.96 gf/tex, both p = 0.043).ConclusionThe tendons repaired with Giftbox technique were biomechanically stronger than those repaired with Krackow technique after six weeks of tendon healing.     

自体腘绳肌腱修复兔巨大肩袖缺损的实验研究

目的研究自体腘绳肌腱修复兔巨大肩袖缺损腱骨愈合的早期实验效果。方法将40只成年雄性新西兰大白兔随机分为3组,分别为正常组(n=8)、模型组(n=8)和实验组(n=24)。正常组相同方式饲养但不予手术处理;模型组将大白兔双前肢肱骨头大结节处切取1.5 cm×1.0 cm的肩袖组织缺损,不予缝合修补后直接缝合皮肤;实验组在模型组的基础上用自体腘绳肌腱修复巨大肩袖缺损。实验组分别于术后第8、16、24周时安乐死8只大白兔后取出双肩标本。将标本处理后分别进行组织形态学分析和生物力学研究测试。结果组织形态学分析结果显示:实验组术后24周腱骨界面胶原纤维明显增多,腱骨隧道连接处可见Sharpey纤维、纤维软骨细胞及纤维软骨等腱骨愈合成分。生物力学研究结果显示实验组肌腱最大负荷随时间延长呈持续增大趋势(各时间点之间比较,P<0.05),术后24周可以获得较强的力学强度。结论应用自体腘绳肌腱修复兔巨大肩袖缺损可以获得良好的腱骨愈合。     

Biomechanical testing of epitenon suture strength in Achilles tendon repairs

BACKGROUND: Recent evidence that early, active mobilization protocols after Achilles tendon repairs increase recovery speed and strength make operative repair strength critical to positive outcomes after Achilles tendon ruptures. While previous research has focused on core (tendon proper) repair techniques, no previous literature has reported testing of core repairs augmented with epitenon sutures, which have been shown to increase the strength of repairs of flexor tendons of the hand. METHODS: Five matched pairs of fresh frozen human Achilles tendons were tested with and without the addition of an epitenon suture to the core repair suture. All specimens were repaired using a No. 2 Ethibond Krakow locking loop core suture. The epitenon suture was added to one tendon randomly chosen from each pair, using a 4-0 nylon suture. All specimens were mounted on an MTS testing machine (MTS Systems Corp., Eden Prairie, MN) and loaded to failure, which was defined as a 1-cm gap formation. RESULTS: The addition of epitenon sutures significantly increased the force necessary to produce a 2-mm gap as compared to core sutures alone by 74%, and it increased the average load to failure by 119%. Also, initial tendon stiffness was 173% greater in tendons reinforced with epitenon sutures. CONCLUSIONS: This study demonstrates that greater resistance to gap formation, approximation of tissue ends, and tensile strength were achieved by the addition of an epitenon suture. Clinical relevance may improve healing by decreased gap formation at the repair site and a lower risk of adhesion formation.     

组织工程肌腱修复陈旧性跟腱断裂伴缺损的疗效观察

目的探讨应用组织工程肌腱修复陈旧性跟腱断裂伴缺损的手术方法及临床效果。方法1999年8月～2002年6月,采用同种异体肌腱来源的成纤维细胞,以5×106/ml细胞密度接种在医用碳纤维与聚羟基乙酸纤维制作的编织带上,体外培养5d后,修复跟腱缺损7例,缺损长度为5～7cm。术后踝跖屈外固定4～6周后开始功能锻炼。结果7例均获随访22～56个月,平均46.9个月。除1例术后伤口延迟愈合外,其余6例均期愈合。无全身及局部不良反应,无跟腱粘连再手术患者。按尹庆水疗效评定标准,优5例,良1例,可1例。结论组织工程肌腱修复跟腱缺损可获较好临床效果,是一种可选择的新治疗方法。     

生物蛋白胶预防鸡趾鞘管区屈肌腱粘连的实验研究

目的 研究生物蛋白胶预防鸡趾鞘管区屈肌腱粘连的作用。方法 种禽褐鸡60只，随机分为生物蛋白胶组（FG）和生理盐水组（NS），每组各30只动物。将第三、四趾趾深屈肌腱切断，作改良Kessler法缝合，不修复腱鞘，然后在腱鞘内肌腱周围及皮下按分组注入相应药物。术后第2、4、6周取材，分别进行大体观察、组织学检查、生物力学测定。结果 术后2、4、6周，组织学检查示两组动物肌腱吻合处的炎症细胞浸润情况及肌腱的愈合进程无明显差别。缝合处粘连半定量评分、将肌腱拉出鞘管所需最大力量、耗功，FG组与NS组相比，差异均无显性意义（P＞0．05）。结论 局部应用FG不能有效预防术后肌腱粘连，但不影响肌腱的愈合进程，也不引起额外的炎症反应。     

Comparison of postoperative early active mobilization and immobilization in vivo utilising a four-strand flexor tendon repair

We evaluated a technique of four-strand double-modified locking Kessler flexor tendon repair in healing tendons. Seventy-two canine flexor digitorum profundus tendons in Zone 2 were repaired and evaluated following either active mobilization or immobilization at 0, 7, 14, 28 and 42 days after surgery. Fifty-six tendons were examined for gap and ultimate strength using a tensile testing machine and 16 were evaluated with standard hematoxylin and eosin, and Masson's trichrome staining. All tendons healed without rupture or gap formation of more than 1 mm, thus demonstrating that this repair technique has enough tensile strength to withstand early active mobilization. The gap and ultimate strength of actively mobilized tendons did not decrease significantly during the first 7 days, and were significantly greater than those of immobilized tendons throughout the 42-day study period. Actively mobilized tendons healed without the extrinsic adhesions and large tendon calluses that were found in immobilized tendons.     

5-氟尿嘧啶防止肌腱粘连的实验研究

目的　探讨 5 氟尿嘧啶 (5 Fu ,5 Fuorouracil)对肌腱粘连的影响。方法　将 42只健康白色纯种来享鸡 ,随机平均分成A组 (实验组 )与B组 (对照组 )。均以右侧第 2、3、4爪为实验对象 ,切断趾深屈肌腱后 ,采用改良Kessler法缝合。A组缝合端用 2 5mg/ml 5 Fu局部滴注 ,B组采用生理盐水滴注。术毕1周、3周、6周处死动物 ,收集A、B 2组右侧缝合的趾深屈肌腱分别进行大体观察 ,生物力学检测 ,组织学与电镜观察。结果　实验组肌腱粘连程度较对照组明显减轻 ,在肌腱修复术后第 3周和第 6周缝合口胶原纤维的含量明显增多 ,肌腱的最大载荷也明显增强 ,统计学处理差异有极显著意义 (P <0 .0 1)。结论　5 Fu有防止肌腱粘连的作用。     

PDLLA可吸收膜厚度对肌腱黏连和愈合影响的初步研究

目的研究聚-DL-乳酸(Poly D,L-lactic acid,PDLLA)可吸收膜厚度对肌腱黏连和愈合的影响。方法31只新西兰大白兔随机分为实验组1(A组,11只)、实验组2(B组,11只)和对照组(C组,9只)3组,建立双后肢第二趾趾深屈肌腱损伤模型。A组肌腱吻合处包裹一层PDLLA可吸收膜,B组肌腱吻合处包裹三层PDLLA可吸收膜,C组不使用PDLLA可吸收膜。术后观察可吸收膜完整性,通过肉眼观察、病理切片、肌腱滑移距离及抗张强度评估肌腱黏连和愈合情况。结果术后2周观察,A组可吸收膜大部分破碎,B组可吸收膜大部分完整。术后6周大体观察,A组可见肌腱吻合口轻度纤维黏连,B组可见肌腱吻合处梭形膨大,表面光滑,C组可见肌腱吻合处广泛致密的纤维黏连。肌腱滑移距离结果,A组与C组、A组与B组之间无明显统计学差异(P>0.05),B组与C组有显著差异(P<0.01)。抗拉强度测试A、B、C三组间差异无统计学意义。结论适当增加PDLLA可吸收膜厚度可有效预防肌腱黏连且不影响肌腱愈合。