Effect of various methods of restoring flexor sheath integrity on the formation of adhesions after tendon injury

The effect of three different methods of restoring flexor sheath integrity on the formation of adhesions around traumatized flexor tendons was studied by use of a chicken animal model. The three methods were: I, Primary sheath repair; II, a fascia patch; and III, a synthetic polytetrafluoroethylene surgical membrane patch. These were compared with controls in which the flexor sheath was excised. Adhesion formation was assessed both biomechanically by measuring the parameter work of flexion, (which represents the resistance to tendon gliding caused by adhesions), and also histologically. At 3 and 6 weeks there was no significant difference in the work of flexion between either the sheath repair or fascia patch digits, and the sheath excised controls. However, use of the synthetic polytetrafluorethylene patch did result in tendon gliding, which was significantly better than the controls. In contrast, at 12 weeks all three methods of sheath reconstruction had similar tendon gliding biomechanics, and all were significantly better than the controls. Histologically, at 3 weeks, the biologic barriers sheath repair and fascia patch were associated with a layer of granulation tissue, which adhered to the underlying tendon. This was similar to the appearance of the sheath excised control digits. The synthetic patch was not associated with a significant inflammatory reaction at this time period and was clearly separated from the tendon. However, by 6 and 12 weeks the granulation tissue in all three sheath reconstruction groups had undergone remodeling to a greater degree than had the controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Ⅱd区双腱早期修复后腱鞘的处理

目的 研究Ⅱd区屈肌腱在单纯切割伤和严重挫伤下双腱修复后腱鞘不同处理的效果。方法 将48只来亨鸡随机分为4组，以鸡双足中趾Ⅱd区为手术对象，每组均行双腱修复。A组：单纯切割伤，腱鞘关闭；B组：单纯切割伤，腱鞘切除；C组：严重挫伤，腱鞘关闭；D组：严重挫伤，腱鞘切除。肌腱修复后6、12周末，分别进行生物力学评定和形态学评定。结果 术后第6、12周末，Ⅱd亚区内屈肌腱单纯切割伤双腱修复后，腱鞘关闭与腱鞘切除效果相当，肌腱的滑动距离、屈曲功能及粘连的表面积比较无统计学意义(P＞0．05)；而严重挫伤双腱修复后，腱鞘切除组肌腱滑动功能明显优于腱鞘关闭组，腱鞘切除组粘连的表面积显著小于腱鞘关闭组，有统计学意义(P＜0．05)。结论 修复手外伤时，Ⅱd区内肌腱单纯切割伤双腱修复后腱鞘可关闭，而在严重挫伤双腱修复后，应作腱鞘切除。     

Hyaluronan in flexor tendon repair

This study assesses the effect of a preparation of hyaluronan (hyaluronic acid) applied topically at the time of flexor tendon repair in a well-established model. The hypothesis is that hyaluronic acid applied topically at the time of flexor tendon repair will decrease adhesions, and will improve clinically the gliding function of the repaired flexor tendon. After transection and repair of the second and fifth flexor tendons of the left forepaw of four mongrel dogs, the second flexor tendon was treated with hyaluronic acid of molecular weight 3.6 x 10(6) daltons applied topically between the synovial sheath and the repair site. The left forepaws were completely immobilized for 5 weeks to optimize the formation of adhesion ingrowth. After death, the repaired tendons and sheaths were removed en bloc, fixed, and dissected. Gross inspection and histologic evaluation of all tendons showed that the quality and quantity of adhesions from the wound repair to the synovial sheath appeared to have been consistently affected by hyaluronan. Hyaluronic acid had a beneficial effect on both the repair site and synovial sheath by decreasing the peripheral inflammatory response and promoting a contact healing process via epitenon and endotenon cell involvement in the repair process.     

Effect of hyaluronic acid/chondroitin sulfate on healing of full-thickness tendon lacerations in rabbits

Viscoat, a high-molecular-weight, highly purified hyaluronic acid (HA) and chondroitin sulfate (CS) compound, was instilled around rabbit plantaris tendon following full-thickness laceration and surgical repair. After 3 weeks of immobilization, no significant difference in adhesion strength or tensile strength of the healing tendons existed between Viscoat-treated tendons and controls. This contradicts previous studies which suggest that hyaluronic acid reduces postoperative tendon adhesions. Further studies examining tendon adhesions after less severe degrees of tendon injury and using direct, quantitative measurement techniques are warranted to demonstrate whether HA has a beneficial effect on tendon healing.     

Fascia patch graft for a digital flexor sheath defect over primary tendon repair in the chicken

The histologic appearance of 14 chicken flexor tendon repair sites with a defect in the tendon sheath was compared with 14 covered by fascia patch grafts. Half the animals (seven with and seven without the patch) were studied 3 weeks after surgery and the other half 8 weeks after surgery. The qualitative microscopic examination showed that the area of healing was better organized with less restrictive-appearing adhesions when the sheath defect was grafted.     

Flexor tendon healing and adhesion formation after Sterispon wrapping: a study in the rabbit

The influence of Sterispon (Allen & Hanbury) wrapping on the healing of the rabbit flexor digitorum profundus tendon sutured within the digital sheath was studied. Control tendons healed in 2 weeks in association with thick adhesions. The wrapped tendons were surrounded with fewer adhesions, but 50 per cent separated. Healing was delayed until adhesions reached the suture site. A sheath of a single layer of mesothelial cells formed on the surface of the Sterispon opposite the tendon and this markedly reduced adhesions at the suture site. The cellular reaction was bland.Sterispon wrapping had a similar effect on tendon healing and adhesion formation as wrapping with other non-absorbable substances and the results support the theory that healing in the digital sheath is necessarily mediated through the formation of adhesions. Sterispon wrapping has been helpful after tenolysis operations.     

Adhesion formation after flexor tendon repair: a histologic and biomechanical comparison of 2- and 4-strand repairs in a chicken model

PURPOSE: Both increased handling and increased bulk at the repair site have been hypothesized as affecting adhesion formation and gliding after tendon repair. Tendons repaired with 2- and 4-strand techniques were compared using both biomechanical and histopathologic measurements to determine the influence of increasing strand number on adhesion formation and gliding. METHODS: The flexor digitorum profundus tendon of the right middle toe of 80 broiler chickens was cut and then repaired with either a single (2-strand) or double (4-strand) modified Kessler core suture, followed by a running epitendinous suture. The limb was immobilized after surgery. Birds were killed at either 3 days or 4 weeks after tendon repair and adhesion formation measured using either biomechanical testing or quantitative and qualitative histology. For biomechanical testing, the tendon was pulled free of the sheath and a force versus displacement curve was generated. Comparisons of peak force and work to peak were made. Histologic specimens were examined by a pathologist blinded to the treatment group who scored the length and density of adhesions and made qualitative observations. RESULTS: Both biomechanical and histologic data showed expected differences in adhesion formation for early (3 days) and late (4 weeks) healing but no significant differences between 2- and 4-strand repairs. Biomechanical testing of 4-week specimens showed a nonsignificant tendency toward greater work required to break adhesions in 4-strand repairs. CONCLUSIONS: Adhesion formation and gliding resistance of tendons after 2- or 4-strand modified Kessler core suture were not significantly different, which suggests that simply increasing the number of strands crossing a repair does not necessarily result in more adhesions or resistance in this model.     

Prevention of tendon adhesions by the reconstruction of the tendon sheath with solvent dehydrated bovine pericard: An experimental study

BACKGROUND: The achievement of the kinetic functions of a finger in full range of motion after the injury and the repair of the flexor tendon has been a challenging issue in hand surgery. Several current studies emphasize the importance of the tendon sheath for the healing of the tendon and for the prevention of the adhesive bands and advise primary repair or reconstruction of them. Various biological and synthetic materials have been used for this purpose with different rates of success. METHODS: In this experimental study, the sheaths of flexor tendons of chicken toe were excised and three groups were observed: group 1, primary sheath not repaired; group 2, sheath repair with autogenous fascia; and group 3, sheath reconstruction with solvent dehydrated bovine pericardium (SDBP). RESULTS: Histopathologic evaluations were performed on the 3rd and 12th weeks to determine the outcome of the repair methods regarding the gliding surfaces of the tendons, adhesion rates, and inflammatory reactions, which are the main issues on the healing of the tendon. The results indicated less formation of adhesions in group 3 compared with groups 1 and 2 (p = 0.001). CONCLUSION: The results showed that SDBP can be used for the reconstruction of the sheaths successively for the prevention of the adhesive bands in flexor tendon surgery.     

Effect of flexor sheath integrity on tendon gliding: a biomechanical and histologic study

The effect on tendon gliding of flexor sheath excision versus incision/closure following primary flexor tendon repair was examined biomechanically and histologically in forty-one chickens. There was no significant difference in either the tendon excursion required to fully flex the digit or in the work of flexion (the integration of the forces that resist tendon gliding during excursion) between the sheath excised and sheath closed groups. The results were unaffected by postoperative immobilization or intermittent passive motion. Histologically, it was noted that at 3 weeks the healing tendon was surrounded by a layer of granulation tissue that was nearly identical in both the sheath excised and the sheath closed digits. Of note was the finding that a synovial lining could not be identified in those digits that had previously undergone sheath closure. However, at 6 weeks postoperatively, a new gliding surface could be identified surrounding the tendon in both the sheath excised and the sheath closed digits. This study indicates that closure of the flexor sheath after primary tendon repair does not improve tendon gliding as measured biomechanically. Despite its repair, the flexor sheath does not maintain its synovial characteristics as demonstrated histologically, and a new sheath must subsequently be formed.     

Flexor Tendon Injuries: II. Operative Technique

The repair of flexor tendons (zones I and II) is a technique-intensive surgical undertaking. It requires a strong understanding of the anatomy of the tendon sheath and the normal relationship between the pulleys and the flexor digitorum superficialis and flexor digitorum profundus tendons in the digit. Meticulous exposure, careful tendon retrieval, and atraumatic repair are extremely important, and the repair should be of sufficient strength to resist gapping and permit the early postrepair application of motion forces. Whenever possible, the tendon sheath should be preserved or repaired, and a smooth gliding surface should be reestablished. The author describes an effective method of tendon retrieval and a simplified technique for a four-strand tendon repair with a supplementary peripheral running-lock suture. The repair is considered to maintain sufficient strength throughout healing to allow a postrepair rehabilitation protocol that will impart passive and modest active stress forces to the repaired tendons. Complications include tendon rupture, digital joint flexion contractures, and adhesions that restrict tendon gliding and ultimately necessitate tenolysis.     

Eight-strand core suture technique for repair of intrasynovial flexor tendon lacerations

The concept of intrinsic tendon healing, the idea that tendons can heal primarily without the ingrowth of fibrous adhesions from the surrounding fibrous flexor sheath, has been validated both experimentally and clinically. The goals of the surgical treatment of intrasynovial digital flexor tendon lacerations are twofold: 1) to achieve a primary tendon repair of sufficient strength so as to prevent repair site gap elongation and possible rupture, and 2) to prevent the formation of intrasynovial adhesions that cause loss of tendon excursion within the flexor tendon sheath. It is well accepted that repair site strength, both at time zero and within the first 6 postoperative weeks, is directly related to the number of core suture strands crossing the repair site. The factor that limits more widespread use of multistrand suture techniques remains the surgeon's ability to perform the repair while also minimizing trauma to the tendon stumps and the circumferential epitenon. We describe an 8-strand core suture technique used at our institution that has been tested ex-vivo, in-vivo in canines, and used in human subjects over the last 4 years with excellent results.     

Effect of synergistic wrist motion on adhesion formation after repair of partial flexor digitorum profundus tendon lacerations in a canine model in vivo.

BACKGROUND: Therapy employing passive finger flexion and active finger extension with the wrist fixed in flexion is commonly used after flexor tendon repair. However, this method of rehabilitation may not produce full tendon excursion because of buckling of the tendon within its sheath with passive flexion. Studies of cadavera suggest that the use of synergistic wrist and finger motion may improve tendon gliding. The purpose of this study was to assess the effects of passive digital motion, performed with either wrist fixation or synergistic wrist motion, on adhesion and gap formation after flexor tendon repair. METHODS: Sixty-six dogs were randomly allocated to two groups. In each group, two flexor digitorum profundus tendons of one forepaw were partially (80%) lacerated and then repaired with a modified Kessler suture. In each group, a different postoperative therapy (wrist fixation or synergistic motion) was performed twice daily. The dogs were killed at one week, three weeks, or six weeks after surgery, and the repaired tendons were evaluated to determine the adhesion grade and adhesion breaking strength. RESULTS: The synergistic motion group had a significantly lower adhesion grade and significantly less adhesion breaking strength than the wrist fixation group at three and six weeks (p < 0.05). At one week, there was no significant difference between the two therapy groups (p > 0.05). CONCLUSIONS: Passive digital flexion and extension with synergistic wrist motion was an effective therapy after repair of partial zone-2 lacerations in a canine model.     

The use of a hydrogel sealant on flexor tendon repairs to prevent adhesion formation

The prevention of peritendinous adhesions after zone II flexor tendon repair poses a significant challenge to hand surgeons. This study evaluates a hydrogel sealant (FocalSeal-L) as a barrier to peritendinous adhesion formation. The deep flexors of toes 2 through 4 were divided and repaired in 30 chickens. Chickens were randomized to tendon repair with (n = 15) or without (n = 15) FocalSeal-L. Each group was further randomized to have their tendons studied postoperatively at 3 (n = 10), 6 (n = 10), or 12 (n = 10) weeks. Histologic evaluation revealed decreased peritendinous adhesion formation in the FocalSeal-L group. Biomechanical analysis demonstrated a decrease in work of flexion in the FocalSeal-L group that was most pronounced at 6 weeks (P = 0.0020). There was no significant difference in breaking strength. Apparently, an effective barrier to peritendinous adhesion formation, this sealant system is easy to use, biocompatible, and bioresorbable. In addition, it is not bulky or restrictive to tendon glide.     

Establishment of an in vivo turkey model for the study of flexor tendon repair

Flexor tendon injuries are common and pose a clinical challenge for functional restoration. The purpose of our study was to assess the adequacy of the turkey as a large animal model for flexor tendon injuries in vivo. Twenty‐four male turkeys underwent surgical flexor tendon cut and repair. Turkeys were allocated to five groups postoperatively: (1) foot casted in extension and sacrificed after 3 weeks; (2) foot casted in extension and sacrificed after 6 weeks; (3) foot casted in flexion and sacrificed after 3 weeks; (4) foot casted in flexion and sacrificed after 6 weeks; and (5) foot casted in flexion for 6 weeks and then free roaming allowed for an additional 3 weeks before sacrifice. After sacrifice, digits were collected and analyzed for adhesion formation, healing at the macrolevel and histologically, and biomechanical properties—including friction, work of flexion, stiffness, and strength of repair. All turkeys survived anesthesia and surgery. Tendon rupture occurred in all extension casts and in 11% of those casted in flexion. Friction and work of flexion were significantly higher in the repaired digit than the control digit. There was a correlation between duration of immobilization and repair strength. Histologically, the tendon healed with tenocytes migrating into the gap and producing collagen fibers. We have, for the first time, studied flexor tendon injury and repair using turkeys in terms of anesthesia, surgical procedures, postoperative care, and animal husbandry. The findings regarding functional and histological results from this novel avian model were comparable to the most commonly used mammal model. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2497–2505, 2018.

     

Remodeling of the gliding surface after flexor tendon repair in a canine model in vivo.

Maintaining a smooth lubricated surface between the flexor tendon and sheath after tendon repair is very important for restoration of digit function. We studied the tendon surface after tendon repair mechanically in a canine model in vivo by measuring frictional force. One hundred and twenty flexor digitorum profundus (FDP) tendons were lacerated to 80% of their cross-section and repaired with either a modified Kessler (MK) or Becker (MGH) repair. The postoperative therapeutic regimen was either synergistic wrist and digit motion (SWM) or passive digit flexion and extension with the wrist fixed in 45 degrees of flexion (FIX). The dogs were sacrificed at one, three, or six weeks postoperatively. Thirty six FDP tendons from normal paws served as the control group, with each control tendon tested in two different conditions: intact and immediately after partial laceration and repair (0 time), making a total of five different timing points (intact, 0 time, one week, three weeks, and six weeks) for each repair type and each postoperative therapy. Frictional force between tendon and proximal pulley was evaluated after breaking any adhesions. Compared to intact tendons, friction was significantly increased immediately after tendon repair. The friction of the MK repair was significantly less than that of the MGH repair at all time and therapy groups, except at six weeks in the SWM group. For the MGH repair, at six weeks friction in the SWM group was significantly less than friction in the FIX group. This study showed that postoperative tendon gliding depends on the method of tendon repair and the postoperative therapy regimen. Furthermore, we have demonstrated that the gliding surface after tendon repair remodels with time.     

Resurfacing with chemically modified hyaluronic acid and lubricin for flexor tendon reconstruction

We assessed surface coating with carbodiimide derivatized hyaluronic acid combined with lubricin (cd‐HA‐Lubricin) as a way to improve extrasynovial tendon surface quality and, consequently, the functional results in flexor tendon reconstruction, using a canine in vivo model. The second and fifth flexor digitorum profundus tendons from 14 dogs were reconstructed with autologs peroneus longus (PL) tendons 6 weeks after a failed primary repair. One digit was treated with cd‐HA‐Lubricin, and the other was treated with saline as the control. Six weeks following grafting, the digits and graft tendons were functionally and histologically evaluated. Adhesion score, normalized work of flexion, graft friction in zone II, and adhesion breaking strength at the proximal repair site in zone III were all lower in the cd‐HA‐Lubricin treated group compared to the control group. The strength at the distal tendon/bone interface was decreased in the cd‐HA‐Lubricin treated grafts compared to the control grafts. Histology showed inferior healing in the cd‐HA‐Lubricin group at both proximal and distal repair sites. However, cd‐HA‐Lubricin treatment did not result in any gap or rupture at either the proximal or distal repair sites. These results demonstrate that cd‐HA‐Lubricin can eliminate graft adhesions and improve digit function, but that treatment may have an adverse effect on tendon healing. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 969–975, 2013     

自体和异体滑膜内、外肌腱移植的实验研究

目的　比较自体和异体滑膜内肌腱 (intrasynovial tendon,IT )及滑膜外肌腱 (extrasynovialtendon,ET)作鞘管内移植后两者愈合过程和粘连的异同。方法　应用兔新鲜自体和深低温冻存的异体趾深屈肌腱 (IT)、腓骨长肌腱 (ET) ,分别移植于兔左后肢第二趾 (IT)、四趾 (ET)鞘管内修复趾深屈肌腱缺损。自体、异体组各 2 1只兔。术后 10天、3、6周取两组移植腱及对侧正常腱作组织学观察 ;术后 4、8周取材作生物力学测定。结果　两组 IT移植后粘连轻 ,而两组 ET移植后粘连明显 ,滑动功能差于 IT移植(F =14.10 ,P <0 .0 1)。术后 8周时异体移植腱的最大抗断裂载荷值低于自体移植腱 (F =10 .11,P <0 .0 1)。结论　鞘管内自体或异体肌腱移植后均有供腱的组织特异性 ,两者 IT移植后滑动功能均优于 ET组。异体肌腱 (IT、ET)移植后的愈合过程慢于自体移植组。     

The use of amniotic membrane in flexor tendon repair: an experimental model

BACKGROUND: The objective of this study was to investigate the use of amniotic membrane as a long-term bioprosthesis in hand surgery.The role of the amniotic membrane was investigated in chickens with regard to the prevention of adhesion formation following tendon repair in zone II. METHODS: In the control group, the flexor tendon sheath was excised and the tendon repaired. In group II, both the flexor digitorum profundus tendon and its sheath were repaired. In group III, the repaired tendon was covered with amniotic membrane. Histological evaluation of the repaired tendons were done at 3, 6 and 12 weeks. RESULTS: Results of histologic examination demonstrated that use of the amniotic membrane significantly reduced the amount of adhesion compared with the other groups. Three months after implantation no remnants of amniotic membrane could be identified at the tendon repair site. CONCLUSIONS: Amniotic membrane is easily prepared, and because of its cost effectiveness, its use in the prevention and treatment of adhesions should always be kept in mind.     

外源性碱性成纤维细胞生长因子对鞘内肌腱愈合和粘连的影响

目的 探讨外源性碱性成纤维细胞生长因子（basic fibroblast growth factor，bFGF）对鞘内肌腱愈合和粘连形成的作用。方法 成年雄性来亨鸡90只随机平均分成3组，每组30只，制备右爪第3趾趾深屈肌腱横断模型。A组肌腱横行切断后原位缝合；B组肌腱断端应用纤维蛋白封闭剂（fibrin sealant，FS）0．6μl后，原位缝合修复横断肌腱；C组则在断端使用bFGF和FS混合物0．6μl（内含bFGF500ng）后，原位缝合修复横断肌腱。术后1、2、4、8周，每组各取6只鸡第3趾行大体及组织学观测，术后8周每组再取6只鸡第3趾行生物力学测定。结果大体观察：术后8周各组肌腱粘连程度分级差异均无统计学意义（P〉0．05）。组织学观测：术后1、2、4、8周成纤维细胞计数及术后4、8周胶原纤维含量，A、B两组间差异均无统计学意义（P〉0．05）；C组与A、B两组比较，术后1、2、4周成纤维细胞数及术后4、8周胶原纤维含量差异均有统计学意义（P〈0．05）。生物力学测定：术后8周，A、B、c组肌腱滑动距离分别为3．44±0．43、3．51±0．56和2．84±0．42mm，屈曲功分别为14．87±1．72、14．08±1．85和20．62±3．52Nmm，最大抗拉力分别为10．34±1．45、11．26±1．83和15．02±2．20N，A、B两组间差异均无统计学意义（P〉0．05），但C组与A、B两组比较，各指标差异均有统计学意义（P〈0．05）。结论 在肌腱断端使用外源性bFGF能促进鞘内肌腱的愈合，但也加重了肌腱的粘连。