Biomechanic comparison of the Teno Fix tendon repair device with the cruciate and modified Kessler techniques

PURPOSE: To compare the mechanical behavior of a novel internal tendon repair device with commonly used 2-strand and 4-strand repair techniques for zone II flexor tendon lacerations. METHODS: Thirty cadaveric flexor digitorum profundus tendons were randomized to 1 of 3 core sutures: (1) cruciate locked 4-strand technique, (2) modified Kessler 2-strand core suture technique, or (3) Teno Fix multifilament wire tendon repair device. Each repair was tested in the load control setting on a Instron controller coupled to an MTS materials testing machine load frame by using an incremental cyclic linear loading protocol. A differential variable reluctance transducer was used to record displacement across the repair site. Cyclic force (n-cycles) to 1-mm gap and repair failure was recorded using serial digital photography. RESULTS: There was no significant difference in differential variable reluctance transducer displacement between the cruciate, modified Kessler, and Teno Fix repairs. The cruciate repair had greater resistance to visual 1-mm repair-site gap formation and repair-site failure when compared with the Kessler and Teno Fix repairs. No significant difference was found between the modified Kessler repair and the Teno Fix repair. In all specimens, the epitenon suture failed before the core suture. Repair failure occurred by suture rupture in the 7 cruciate specimens that failed, with evidence of gap formation before failure. Seven of 10 modified Kessler repairs failed by suture rupture. All of the Teno Fix repairs failed by pullout of the metal anchor. CONCLUSIONS: The Teno Fix repair system did not confer a mechanical advantage over the locked cruciate or modified Kessler suture techniques for zone II lacerations in cadaveric flexor tendons during cyclic loading in a linear testing model. This information may help to define safe boundaries for postoperative rehabilitation when using this internal tendon repair device.     

Biomechanical comparison of double grasping repair versus cross-locked cruciate flexor tendon repair

Purpose

This study was conducted to compare the in vitro biomechanical properties of tensile strength and gap resistance of a double grasping loop (DGL) flexor tendon repair with the established four-strand cross-locked cruciate (CLC) flexor tendon repair, both with an interlocking horizontal mattress (IHM) epitendinous suture. The hypothesis is that the DGL-IHM method which utilizes two looped core sutures, grasping and locking loops, and a single intralesional knot will have greater strength and increased gap resistance than the CLC-IHM method.

Methods

Forty porcine tendons were evenly assigned to either the DGL-IHM or CLC-IHM group. The tendon repair strength, 2-mm gap force and load to failure, was measured under a constant rate of distraction. The stiffness of tendon repair was calculated and the method of repair failure was analyzed.

Results

The CLC-IHM group exhibited a statistically significant greater resistance to gapping, a statistically significant higher load to 2-mm gapping (62.0 N), and load to failure (99.7 N) than the DGL-IHM group (37.1 N and 75.1 N, respectively). Ninety percent of CLC-IHM failures were a result of knot failure whereas 30 % of the DGL-IHM group exhibited knot failure.

Conclusions

This study demonstrates that the CLC-IHM flexor tendon repair method better resists gapping and has a greater tensile strength compared to the experimental DGL-IHM method. The authors believe that while the DGL-IHM provides double the number of sutures at the repair site per needle pass, this configuration does not adequately secure the loop suture to the tendon, resulting in a high percentage of suture pullout and inability to tolerate loads as high as those of the CLC-IHM group.     

Biomechanical analysis of knotless flexor tendon repair using large-diameter unidirection barbed suture

Purpose

In traditional flexor tendon repairs, suture knots can be sites of weakness, impair tendon healing, stimulate an inflammatory response, and increase the bulk of the tendon repair. Because of this, there has been an increased interest in knotless flexor tendon repair using barbed suture. Since knots are not required, it may be possible to increase the strength of the tendon repair by using a large-diameter barbed suture. The purpose of this study was to biomechanically compare a traditional four-strand tendon repair using 3-0 braided polyester with a similar knotless four-strand tendon repair using 0 unidirectional barbed suture.

Methods

Twenty-two matched cadaveric flexor digitorum profundus tendons were lacerated and assigned to repair by a four-strand modified Kirchmayr–Kessler technique using 3-0 braided polyester (n = 11) or knotless four-strand modified Kirchmayr–Kessler repair using 0 unidirectional barbed suture (n = 11). Repaired tendons were linearly distracted to failure at 20 mm/min after 1 N preload. Maximum load and load at 2-mm gap formation were recorded. Maximum load and load at 2-mm gap formation were compared with the Student’s t test, and p values ≤ 0.05 were considered significant.

Results

The mean maximum load of the barbed, knotless suture repair was higher than that of the traditional repair (52 vs. 42 N). There was no difference between the two groups in the mean load required to produce a 2-mm gap.

Conclusions

The four-strand knotless tendon repairs using a large-diameter unidirectional barbed suture were stronger than the traditional four-strand repairs using 3-0 braided polyester, and had similar 2-mm gap resistance.     

Spontaneous flexor tendon ruptures of the hand: case series and review of the literature

Spontaneous flexor tendon ruptures within the hand are incompletely understood. We report 5 cases of spontaneous tendon rupture involving the flexor digitorum profundus tendon. One case involves an abnormal intertendinous connection between the ring and small finger profundus tendons and another involves a lumbrical muscle variant. To our knowledge, the latter has not been reported in association with spontaneous tendon rupture. In reviewing the literature for spontaneous flexor tendon ruptures, a total of 50 spontaneous ruptures in 43 cases was found. The majority involve the profundus tendon of the small finger in the palm. The ruptures most often occur during periods of peak strain but can also occur without identifiable trauma. The pathogenesis of spontaneous tendon ruptures is still unclear and is likely multifactorial. Spontaneous flexor tendon ruptures of the hand occur more often than one might recognize.     

手部开放性屈肌腱损伤的早期修复

目的探讨手部屈肌腱损伤早期修复及早期功能锻炼对手部功能恢复的疗效。方法统计我院自2008年1月-2009年5月手部屈肌腱损伤患者80例124指,共计221条肌腱,其中I区16条,Ⅱ区89条,Ⅲ区36条,Ⅳ区10条,V区70条,均予早期修复,术后早期辅以适当的功能锻炼,以TAM评价法进行功能评价。结果术后随访4个月～1年,随访72例,失访8例。患指TAM优良率达94．64％。结论早期修复手部开放性屈肌腱损伤,术后辅以规范的功能锻炼对手部功能恢复具有良好的疗效。     

Botulinum Toxin Use as an Adjunctive Modality in a Patient with Multiple Flexor Tendon Ruptures

Botulinum toxin A has been described in treatment protocols for several disease processes, from primary axillary hyperhydorosis to esophageal dysfunction. It is best known for its use in plastic and dermatological practices. Botulinum toxin has a straightforward mechanism of action. The toxin inhibits acetylcholine release at the neuromuscular junction causing a chemical denervation, which ceases contractions of the muscle. With its minimal side effect profile, botulinum toxin should be considered when muscle spasm is a detriment. This case involves an injury to the hand of a patient with a history of intermittent diffuse muscle spasms. Subsequently, due to the patient's previous upper extremity muscle spasms, repeated flexor tendon repair ruptures of the index finger occurred until botulinum toxin was administered to the offending muscle. The patient has not required any additional surgical interventions for the repaired tendon and is now actively flexing all digits. This case report demonstrates how botulinum toxin can be used in a clinical scenario when decreased muscle activity is desired to promote tendon healing.     

A comparison of tenocytes and mesenchymal stem cells for use in flexor tendon tissue engineering

PURPOSE: Tissue-engineered tendon grafts will meet an important clinical need. To engineer tendons, we used acellularized allogeneic tendon as scaffold material. To determine the ideal cell type to seed the scaffolds, we studied in vitro characteristics of epitenon tenocytes, tendon sheath fibroblasts, bone marrow-derived mesenchymal stem cells (BMSCs), and adipoderived mesenchymal stem cells (ASCs). Subsequently, we implanted reseeded acellularized tendons in vivo as flexor tendon grafts. METHODS: Tenocytes, sheath fibroblasts, BMSCs, and ASCs were obtained from adult rabbits. For all cell lines, collagen 1, 2, and 3 immunocytochemistry was performed, and proliferation was assessed by hemacytometry and senescence by beta-galactosidase staining. Flexor tendons were acellularized after harvest. Tendons were assessed by histology after in vitro reseeding with each of the cell types after 1, 4, and 8 weeks. Finally, reseeded tendons and controls were implanted in a flexor profundus tendon defect. After 6 weeks, the reseeded tendons were harvested and assessed by histology. Statistical analysis for cell proliferation was performed using analysis of variance and t-tests with Bonferroni correction. RESULTS: All cell types had similar collagen expression. Cell proliferation was higher in ASCs in late passage compared with early passage and in ASCs compared with epitenon tenocytes at late passage. The other cell types were similar in growth characteristics. No senescence was detected. In vitro assessment of reseeded constructs showed the presence of cells on the construct surface. In vivo assessment after implantation showed viable cells seen within the tendon architecture in all cell types. CONCLUSIONS: This study suggests that the four cell types may be successfully used to engineer tendons. Adipoderived mesenchymal stem cells proliferate faster in cell culture, but the cell types were similar in other respects. All could be used to successfully repopulate acellularized tendon in vivo as flexor tendon grafts.     

Hypertrophy of the flexor hallucis longus muscle after tendon transfer in patients with chronic Achilles tendon rupture

BackgroundFlexor hallucis longus tendon (FHLT) transfer has become a popular method for reconstructing a chronic Achilles tendon rupture (ATR). The purpose of this study was to evaluate the clinical outcomes and possible hypertrophy of the FHL muscle after FHLT transfer in patients with chronic ATR.MethodsSeven patients with chronic ATR underwent an FHLT transfer to heel through single incision. The patients were clinically evaluated 27 (16–39) months after the surgery. The patient satisfaction was assessed with Achilles Tendon Total Rupture Scale (ATRS). Isokinetic strength was measured from both legs. The FHL muscle hypertrophy was evaluated from MRI of both legs. All subjects also performed a gait analysis with an instrumented walkway system (GAITRite^®).ResultsThe plantar flexion strength was 16.1% (-45, 7-2, 4%) weaker in the operated leg. ATRS scores averaged 70.3. Marked hypertrophy, +52% (9–104%) of the FHL muscle was seen in the operated leg compared to the non-operated leg. The gait analysis did not show any marked pathology in any of the patients.ConclusionsA mean hypertrophy of 52% of the FHL muscle was found after FHLT transfer for the chronic ATR. This indicates strong adaptation capacity of this muscle after FLHT transfer in situation where the function of the gastro-soleus complex was severely impaired preoperatively. The reconstruction of chronic ATR with FHLT transfer provided a good functional outcome and excellent patient satisfaction.     

微创切取长屈肌腱重建慢性跟腱断裂

目的探讨微创切取长屈肌腱转移重建慢性跟腱断裂的临床效果。方法 2006年7月-2009年12月,收治22例22足慢性跟腱断裂患者。男16例,女6例;年龄28～65岁,中位年龄48岁。21例有患足用力蹬地史,1例无明显诱因。患者出现症状至手术时间为27～1 025 d,中位时间51 d。均有走路无力症状,Thompson试验呈阳性。根据美国矫形足踝协会(AOFAS)踝与后足疗效评价标准评分为(53.04±6.75)分。MRI示跟腱缺损长度为4.2～8.0 cm。术中作中足足底内侧切口和趾间关节跖侧平行横纹的小切口分步切取长屈肌腱,切取长度为超过跟骨结节10.5～13.5 cm,作3束反折编织缝合。界面螺钉或锚钉于跟骨后结节固定肌腱。结果术后患者切口均Ⅰ期愈合,无早期并发症发生。22例均获随访,随访时间12～42个月,平均16.7个月。术后12个月根据AOFAS踝与后足疗效评价标准评分为(92.98±5.72)分,与术前比较差异有统计学意义(t=—40.903,P=0.000);获优18例,良2例,可2例,优良率90.9%。随访期间均未见胫、腓肠神经损伤、跖底部痛性瘢痕、足底内外侧神经损伤。结论微创切取长屈肌腱转移重建慢性跟腱断裂具有切口小、术后恢复快、肌腱固定强度高以及并发症少的优点。     

Gross and histological analysis of healing after dog flexor tendon repair with the Teno Fix device

The purpose of this study was to examine the in vivo characteristics of the stainless-steel Teno Fix device used for flexor tendon repair. The common flexor digitorum superficialis tendon was transected in 16 dogs and repaired with the device. The animals were euthanized at 3, 6, or 12 weeks postoperatively. Difficulties with cast immobilization led nine of 16 animals to be full weight bearing too early, leading to rupture of their repairs. The seven tendons with successful primary repairs (gap <2mm) underwent histological examination. This in vivo study demonstrates that use of the Teno Fix in "suture" of dog flexor tendons did not lead to scarring at the tendon surface, does not cause an inflammatory reaction within the tendon and does not interfere with tendon healing.     

A comparative analysis of the six-strand double-loop flexor tendon repair and three other techniques: a human cadaveric study

The ideal zone II flexor tendon repair would be easy to perform, cause minimal scarring, and be strong enough to allow early active motion. A 6-strand loop suture technique devised by the senior author (T.M.T.) was studied in vitro. Forty flexor tendons were harvested from fresh-frozen human hands and divided into 4 groups of 10 tendons each. Each group of tendons was repaired with a specific technique: group 1, the modified Kirchmayr (modified Kessler) technique; group 2, the single-loop 2-strand technique described by Tsuge; group 3, Tsai's double-loop 4-strand modification of Tsuge's technique; and group 4, Tsai's double-loop 6-strand modification of Tsuge's technique. Gap resistance of each repair technique was recorded on a computer using a Differential Variable Reluctance Transducer (MicroStrain, Burlington, VT) and on videotape to record first gap formation, 1-mm and 2-mm gap formation, and maximum load. Statistically significant differences between groups were as follows: at first gap formation between the 2-strand and 6-strand loop suture techniques, and at maximum load between the modified Kessler and 4-strand, modified Kessler and 6-strand, 2-strand and 4-strand, and 2-strand and 6-strand loop suture techniques. The 6-strand double-loop suture technique had a higher tensile strength than the other techniques, as measured in this model at each stage in our experiment. The 6-strand double-loop suture technique simplifies flexor tendon repair. It improves the repair's strength and its resistance to gapping without increasing tendon handling or bulk. This increased repair strength allows us to pursue a more aggressive rehabilitation program.     

Achilles' tendon ruptures: Operative versus nonoperative management

Athletes, both professional and recreational, remain vulnerable to a sudden, complete tear of the Achilles' tendon. The debate concerning treatment of this debilitating injury has been ongoing for years. The optimum treatment strives to return the athlete to their preinjury level of competition with a minimal rate of major complications. Closed treatment offers simplicity, low cost, and avoidance of neurological or wound complications. Unfortunately, closed treatment may also have a higher rerupture rate, making it less desirable in the athletic population. Also, nonoperative treatment as compared to repaired tendons may result in decreased strength and endurance. In the athletic population, the high-performance demands and need to avoid reinjury may favor surgical treatment.     

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.     

应用双津下缝合法修复跟腱断裂疗效分析

目的探讨采用0号可吸收普迪思圈套线(PDS-Ⅱ线)双津下缝合法修复跟腱断裂的临床疗效。方法 2005年1月-2008年12月,收治36例跟腱断裂患者。男29例,女7例;年龄21～50岁,平均36岁。运动损伤25例,摔伤4例,锐器割伤6例,其他伤1例。新鲜闭合损伤22例,新鲜开放损伤6例,伤后至入院时间1～10 d,平均6 d;陈旧性闭合损伤8例,伤后至入院时间43～63 d,平均51 d。提踵试验及Thopmson征均呈阳性。患者均采用0号可吸收PDS-Ⅱ线双津下缝合法修复。术后于踝跖屈30°位短腿石膏固定6周后,开始功能锻炼。结果术后2例陈旧性跟腱断裂患者切口愈合不良,经对症治疗后切口愈合;其余切口均Ⅰ期愈合。患者均获随访,随访时间12～24个月,平均15个月。随访期间均未发生跟腱再次断裂及反射性交感神经营养不良。患者踝关节活动度与健侧相比,7例无减少,16例减少1～10°,12例减少10～20°,1例减少25°。根据Termann跟腱损伤临床评价标准,评分为74～96分,平均90分;获优24例,良11例,可1例,优良率为97.2%。结论双津下缝合法手术操作简便,缝线在腱内无横行交叉,修复断裂跟腱后对其血运影响小。PDS-Ⅱ线可提供高强度张力,并可完全吸收,不易发生局部粘连。采用该方法修复跟腱断裂术后并发症发生率较低,可获得较好疗效。     

Flexor tendon ruptures in the rheumatoid patient

In patients with rheumatoid arthritis, flexor tendon ruptures are much less common than extensor tendon ruptures. The most common cause of flexor tendon rupture is direct abrasion on a bony prominence. The most common flexor tendon rupture is the flexor pollicis longus (FPL) attritional rupture within the carpal canal. The best treatment for flexor tendon rupture is prevention. Flexor tenosynovectomy is indicated when medical management does not control wrist tenosynovitis. A variety of techniques are available for reconstruction of flexor tendon ruptures. Irrespective of the reconstructive method, the results of reconstruction for rheumatoid flexor tendon rupture are poor.