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.     

Zone I flexor profundus tendon repair in children 5-10 years of age using 3 "figure of eight" sutures followed by immediate active mobilization

A review of the English medical literature over the last 20 years reporting on flexor profundus lacerations revealed only 55 reported cases of zone I flexor profundus lacerations in children. The standard repair technique in young children (5-10 years of age) has been either tendon reinsertion into bone (usually Bunnell technique) for distal zone I injuries or a 2-strand repair (usually modified Kessler technique) for proximal zone I injuries. We report on 22 children (5-10 years of age) with zone I flexor profundus tendon lacerations (10 children had distal zone I injury and 12 had proximal zone I injury) repaired with a 6-strand technique (3 separate "figure of 8" sutures) followed by early postoperative active mobilization. There were no ruptures. Using the Strickland and Glogovac criteria (on the basis of the net active motion of both the interphalangeal joints), all children qualified for an excellent outcome. However, using Moremen and Elliot criteria (on the basis of the net active motion of the distal interphalangeal joint only), 11 children had an excellent outcome, 3 had a good outcome, and 8 had a fair outcome. Our results were compared with previously reported series. It was concluded that the 6-strand figure of 8 suture technique may be used in pediatric zone I injuries and it is strong enough to allow safe early postoperative active mobilization in the 5- to 10-year age group children.     

Flexor tendon repair in children with zone 2 injuries: an innovative technique using autogenous vein

Objectives

This is a new technique for tendon repair that may improve the results of existing methods.

Methods

The study is a nonrandomized retrospective study using historical (nonconcurrent) controls. From May 1994 to March 2004, 53 children aged 5 to 15 years requiring tendon repair (test group) were compared to 53 children conventionally repaired (control group). All patients had flexor tendon injuries, involving zone 2. In the test group (53 patients), a modified Kessler repairing of tendons with 4-0 prolene was used, followed by a core suture of running 7-0 nylon or prolene epitendinous suture. After the tendon repair, a segment of vein through which the tendon had been passed before or a vein patch used as a tendon sheath substitute was used to repair the sheath defects. The results during 6 months of follow-up were compared with those of the control group that were operated using the conventional technique (modified Kessler method).

Results

We assessed the results by measuring the range of motion of the metacarpophalangeal, distal interphalangeal, and proximal interphalangeal joints in the follow-up period and graded them as excellent, good, fair, and poor. In the test group, 86% were graded as excellent, 11% good, 3% fair, and 0% poor results; and in the control group, 0% were excellent, 12% good, 38% fair, and 50% poor results. The differences were significant (P < .005).

Conclusions

Our preliminary results appeared encouraging when compared with the outcomes achieved by the conventional tendon repair technique. As the new technique decreases the need for intensive physiotherapy, it may serve as a substitute method for the conventional tendon repair and eventually become a standard technique in the future.     

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.     

Results of 4-strand modified Kessler core suture and epitendinous interlocking suture followed by modified Kleinert protocol for flexor tendon repairs in Zone 2

Objective

There has been no consensus in literature for the ideal flexor tendon repair technique. The results of zone 2 flexor tendon lacerations repaired primarily by 4 strand Modified Kessler core suture and epitendinous interlocking suture technique followed by Modified Kleinert protocol were investigated.

Does Strand Configuration and Number of Purchase Points Affect the Biomechanical Behavior of a Tendon Repair? A Biomechanical Evaluation Using Different Kessler Methods of Flexor Tendon Repair

This study compares the mechanical properties of modified Kessler and double-modified Kessler flexor tendon repair techniques and evaluates simple modifications on both methods. Forty fresh sheep flexor tendons were divided equally into four groups. A transverse sharp cut was done in the middle of each tendon and then repaired with modified Kessler technique, modified Kessler with additional purchase point in the midpoint of each longitudinal strand, double-modified Kessler technique, or a combination of outer Kessler and inner cruciate configuration based on double-modified Kessler technique. The tendons were tested in a tensile testing machine to assess the mechanical performance of the repairs. Outcome measures included gap formation and ultimate forces. The gap strengths of the double-modified Kessler technique (30.85 N, SD 1.90) and double-modified Kessler technique with inner cruciate configuration (33.60 N, SD 4.64) were statistically significantly greater than that of the two-strand modified Kessler (22.56 N, SD 3.44) and modified Kessler with additional purchase configuration (21.75 N, SD 4.03; Tukey honestly significant difference test, P < 0.000). There were statistically significant differences in failure strengths of the all groups (analysis of variance, P < 0.000). With an identical number of strands, the gap formation and ultimate forces of the repairs were not changed by additional locking purchase point in modified Kessler repair or changing the inner strand configuration in double-modified Kessler repair. The results of this study show that the number of strands across the repair site together with the number of locking loops clearly affects the strength of the repair; meanwhile, the longitudinal strand orientation and number of purchase points in a single loop did not affect its strength.     

A biomechanical comparison of multistrand flexor tendon repairs using an in situ testing model

An in situ testing model was used to evaluate the performance of zone II flexor tendon repairs and to compare the biomechanical properties of 4-strand repairs with 2- and 6-strand repairs. Fifty digits from human cadaveric hands were mounted in a custom apparatus for in situ tensile testing. Intratendinous metallic markers were placed so that gap formation could be determined by fluoroscopy during tensile testing. Three 4-strand repairs (the 4-strand Kessler, the cruciate, and a locked modification of the cruciate repair) were compared with the 2-strand Kessler and the 6-strand Savage repairs. Ultimate tensile strength, load at 2-, 3-, and 4-mm gap formation, and work of flexion were determined. Work of flexion, while increased for the multistrand repairs, did not show a statistically significant correlation with the number of strands crossing the repair site. The tensile strength of the 6-strand repair was significantly greater than each of the 2- or 4-strand repairs. The tensile strength of all 4-strand repairs was significantly greater than the 2-strand repair. The 6-strand repair and the 2 cruciate repairs demonstrated a statistically increased resistance to gap formation compared with the 2-strand Kessler repair, but notably there was no statistically significant difference in gap resistance between the 2and 4-strand Kessler repairs. This in situ tensiletesting protocol demonstrated that 4- and 6-strand repairs have adequate initial strength to withstand the projected forces of early active motion protocols. Three of the 4 multistrand repairs demonstrated improved gap resistance compared with the 2-strand repair. The presence of the second suture in the Kessler configuration significantly increases its strength but not its gap resistance.     

Clinical Results of Flexor Tendon Repair in Zone II Using a six Strand Double Loop Technique

The purpose of this study is to report the clinical results after repair of flexor tendon zone II injuries utilizing a 6-strand double-loop technique and early post-operative active rehabilitation. We retrospectively reviewed 22 patients involving 51 cases with zone II flexor tendon repair using a six strand double loop technique from September 1996 to December 2012. Most common mechanism of injuries was sharp lacerations (86.5 %). Tendon injuries occurred equally in manual and non-manual workers and were work-related in 33 % of the cases. The Strickland score for active range of motion (ROM) postoperatively was excellent and good in the majority of the cases (81 %). The rupture rate was 1.9 %. The six strand double loop technique for Zone II flexor tendon repair leads to good and excellent motion in the majority of patients and low re- rupture rate. It is clinically effective and allows for early postoperative active rehabilitation.     

Utility of early active motion for flexor tendon repair with concomitant injuries: A multivariate analysis

IntroductionFlexor tendon injury often occurs with concomitant injuries such as fracture, vascular injury, and extensor tendon injury. These injuries are repaired independently, without a comprehensive strategy. We aimed to identify the effect of concomitant injuries and treatment choice on the outcome of flexor tendon repair.Patients and methodsWe evaluated 118 fingers of 102 adult patients with zone 1–3 flexor digitorum profundus (FDP) tendon injuries who underwent primary surgery at our hospital between April 2009 and December 2017. The 2-strand pull-out, 4-strand Tsuge, 6-strand Lim & Tsai, and 8-strand cross-locked cruciate suturing techniques were used. We performed multivariate analyses, with the active range of motion (AROM) of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints as dependent variables, and age, existence of concomitant injuries, and their treatment as independent variables.ResultsThe average AROM of the PIP + DIP joints was 130° at the last follow-up, and ‘excellent’ or ‘good’ function was obtained in 74 (63%) of 118 fingers by using the Strickland criteria. Old age, concomitant diaphyseal fractures, and specific methods of osteosynthesis, such as pinning, flexor digitorum superficialis injury, and immobilisation for 3 weeks, significantly worsened the results. However, wiring for osteosynthesis and early active motion protocol improved postoperative functional outcome. Although the outcome did not differ among the suture techniques, the 4-strand Tsuge procedure was performed for the two surgically confirmed ruptures of repair that occurred in our series.DiscussionWe clarified the superiority of early mobilisation protocols with rigid osteosynthesis procedure, other than pinning. To minimise tendon adhesion or joint stiffness, surgeons should repair the tendon and fractured bone appropriately, to ensure early mobilisation without serious complications.     

Clinical results of flexor tendon repair in zone II using a six-strand double-loop technique compared with a two-strand technique

The clinical and functional results of 46 patients who underwent zone II flexor tendon repair using the Lim/Tsai technique combined with the Kleinert/Duran early active mobilisation regime and place and hold exercises were assessed. The results were compared with 25 patients who were treated by the modified Kessler technique and the Kleinert/Duran regime alone. After a follow-up of 8 to 17 weeks, the Lim/Tsai group had a better grip strength and a significantly better total active motion of 141 degrees compared with 123 degrees . The rupture rates (Lim/Tsai: 1/51; Kessler: 3/26) and the extension deficits were not statistically different in the two groups. However, the complication rate was significantly lower and the average time of treatment was significantly shorter in the Lim/Tsai group. These results support the use of the Lim/Tsai six-strand repair technique in zone II flexor tendon injuries and early active mobilisation without rubber-band traction.     

TwinFix带线锚钉辅助改良Kessler法修补陈旧性跟腱断裂

目的 探讨TwinFix带线锚钉辅助改良Kessler法修补陈旧性跟腱断裂的临床疗效.方法 采用TwinFix带线锚钉辅助改良Kessler法修补陈旧性跟腱断裂患者11例,术中用改良Kessler法对位缝合跟腱断端,再用2枚TwinFix带线锚钉辅助固定断裂跟腱.术后予患侧下肢屈膝90°、踝跖屈30°位长腿石膏托固定,3周后改踝跖屈石膏托固定.结果 11例均获随访,时间3～18个月.患者均未发生切口延期愈合、感染、皮肤坏死和跟腱再断裂等并发症.采用Arner-Lindholm评分标准评价疗效:优7例,良3例,差1例.结论 TwinFix带线锚钉辅助改良Kessler法手术操作简便,是修补陈旧性跟腱断裂的有效方法.     

Zone II tendon repairs augmented with autogenous dorsal tendon graft: a biomechanical analysis

We investigated the biomechanical properties of a new technique for tendon repair that reinforces a standard suture with an autogenous tendon graft. A dynamic in situ testing apparatus was used to test 40 flexor digitorum profundus tendons harvested from fresh-frozen cadaver hands. The tendons were cut and repaired using 1 of 4 suture techniques: 2-strand modified Kessler, 4-strand modified Kessler, 6-strand modified Savage, and 2-strand modified Kessler augmented with autogenous dorsal tendon graft. The augmented repair uses 1 slip of the flexor digitorum superficialis tendon secured to the dorsal surface of the repair site with a continuous stitch. Ultimate tensile strength, resistance to gap formation, and work of flexion were measured simultaneously on an in situ tensile testing apparatus. No significant difference in tensile strength was found between the augmented repair and the 6-strand Savage repair. The augmented repair and the 6-strand Savage repair showed significantly greater ultimate tensile strength than the 2- and 4-strand repairs. The augmented repair had significantly greater resistance to 2 mm gap formation than the other 3 repairs. We were unable to show a significant difference in work of flexion between the repairs with the numbers tested (n = 10). Our findings suggest that the augmented repair is strong enough to tolerate the projected forces generated during active motion without dehiscence or gap formation at the repair site.     

Biomechanical analysis of the cruciate four-strand flexor tendon repair

The purpose of this study was to develop and test in vitro a new flexor tendon suture technique that was simple and easy to perform, yet strong enough to withstand the projected forces of an in vivo active motion rehabilitation protocol. Forty human cadaveric flexor digitorum profundus tendons were divided and repaired using 1 of 4 suture techniques (the modified Kessler, the Strickland, the modified 4-strand Savage, and the Cruciate 4-strand repairs). Each repair was tested using a slow-test machine and displacement control at 2 mm/s. Force applied, the resultant gap, and ultimate tensile strength were recorded and statistical comparisons were performed using a two-tailed Student's t-test with level of significance set at p = .05. The Cruciate suture technique was demonstrated to be nearly twice as strong to 2-mm gap formation (44 N) compared with the Kessler, Strickland, and Savage repairs. Ultimate tensile strength was also significantly stronger for the Cruciate technique (56 N) than the Kessler, Strickland, or Savage repairs. The technique was significantly faster to perform than the Savage or Strickland repairs and was comparable in repair time to the 2-stranded Kessler repair. The design of the new suture technique allowed the tendon repair to be completed with the ease and speed of a 2-strand technique, but bestowed on the repair strength that exceeded current 4-strand techniques.     

Effects of direction of tendon lacerations on strength of tendon repairs

PURPOSE: We compared the tensile strength of different repair configurations on tendons with oblique and transverse lacerations. METHOD: Seventy-two fresh pig flexor tendons were divided randomly and repaired using the modified Kessler, the cruciate, or the 4-strand Massachusetts General Hospital (MGH) repair methods. The tendons were lacerated either transversely or obliquely. They were repaired with conventional and oblique suture repairs. The 2-mm gap formation force and ultimate strength were determined as biomechanical performance for each repair. RESULTS: The gap formation and ultimate strength of the tendons vary with orientations of tendon lacerations and suture methods. In the tendons repaired with the modified Kessler or the cruciate methods, the 2-mm gap formation and ultimate strength of obliquely cut tendons were significantly lower than those of transversely cut tendons. The obliquely placed modified Kessler or cruciate sutures significantly improved the repair strength in the tendons with an oblique laceration. In the tendons repaired with the MGH method, no statistical differences were found in the repair strength of obliquely and transversely lacerated tendons. CONCLUSIONS: The direction of tendon lacerations affects strength of certain repair configurations. The nonlocking modified Kessler or the cruciate tendon repairs are weakened considerably when the tendon laceration is oblique but their mechanical performance is strengthened by re-orienting the repair strands to lie parallel to the laceration. The cross-locked configuration of the MGH repair is not affected by the obliquity of the tendon laceration.     

联合应用半腱肌腱与股薄肌腱越顶重建前交叉韧带

目的 探讨联合应用半腱肌腱与股薄肌腱越顶重建前交叉韧带的外科技术和疗效。方法 自１９９３年１月～１９９６年１２月,１６例前交叉韧带撕裂伤患者接受了联合半腱肌腱与股薄肌腱越顶重建手术治疗。其中男１４例,女２例。随访时间１３～３６个月,平均２０．３个月。结果 按膝关节疗效评定标准,优６例（３７．５％）,良８例（５０．０％）,可２例（１２．５％）,优良率８７．５％。大部分患者在步行和日常生活能力方面均有     

Flexor tendon repair in zone II with 6-strand techniques and early active mobilization

PURPOSE: There are many biomechanic studies of 6-strand suture techniques for active mobilization, but few reports have described the clinical outcome in zone II flexor tendon lacerations. We discuss the clinical results of zone II flexor tendon repair using 2 of these techniques followed by controlled early active mobilization. METHODS: Six-strand sutures using the number 1 technique by Yoshizu or a triple-looped suture technique were used to repair flexor tendons in 27 fingers from 21 consecutive patients. Fingers were mobilized by combining active extension and passive or active flexion in a protective splint for the first 3 weeks after surgery. The follow-up period averaged 13 months. RESULTS: Based on the original Strickland criteria, the results were excellent in 17 fingers, good in 9, and fair in 1. The average flexion was 62 degrees for distal interphalangeal joints and 91 degrees for proximal interphalangeal joints. None of the repaired tendons ruptured. CONCLUSIONS: The 6-strand flexor tendon suture technique followed by controlled active mobilization protected with a dorsal splint is safe, produces no ruptures, and achieves very good results in zone II flexor tendon laceration repair. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level II.     

儿童Ⅱ区指屈肌腱损伤21例分析

目的探讨儿童Ⅱ区指屈肌腱损伤的治疗方法和疗效。方法１９９０年至１９９７年间共收治２１例２３指儿童Ⅱ区指屈肌腱损伤,分析其病史后进行总结。其中男１９例,女２例,年龄５～１４岁,平均１２．１岁。早期１０例１０指,用０号丝线作Ｋｅｓｓｌｅｒ或双十字法缝合。后期１１例１３指在手术显微镜下,用５－０无创尼龙线缝合肌腱及修复腱鞘,均用Ｋｅｓｓｌｅｒ法缝合。非急性期修复者在腱周放置透明质酸钠。结果按ＴＡＭ法评定疗效,早期１０例１０指中,优２指,良６指,可２指,优良率为８０％。后期１１例１３指中,优８指,良５指,优良率为１００％。两组总优良率达９１．３％。结论儿童Ⅱ区指屈肌腱损伤修复后疗效较佳;应用透明质酸钠有助于功能的恢复。     

Repair of flexor digitorum profundus tendon avulsions from bone: an ex vivo biomechanical analysis

Avulsions or distal transections of the flexor digitorum profundus tendon are typically repaired by direct suture of the tendon stump to the distal phalanx. The optimal repair technique to withstand in vivo rehabilitation forces is unknown. Our objective was to determine the time-zero tensile mechanical properties of 4-strand tendon-bone repair site constructs performed with 3-0 and 4-0 sutures and with modified Kessler and modified Becker grasping techniques. We hypothesized that the 3-0 modified Becker grasping suture technique not described previously for the reattachment of tendon to bone would show improved biomechanical properties compared with the 4-0 or modified Kessler techniques. All modified Kessler repairs failed by suture pullout from the tendon, whereas all modified Becker repairs failed by rupture of the suture at the tendon-bone junction. Although the 3-0 modified Becker repair group showed greater ultimate force then the other groups (p <.01), tendon-bone gap observed did not differ markedly between Becker or Kessler groups. Neither suture caliber nor repair technique had a notable effect on strain at 20-N force, suggesting that early gap formation at the tendon-bone repair site may occur regardless of technique.     

Tensile strength of modified 4-strand cruciate technique for transversely or obliquely lacerated tendons

PURPOSES: To assess the tensile strength of the modified 4-strand cruciate technique for obliquely lacerated tendons, and to compare the findings with the strength of transversely lacerated tendons repaired at various grasping depths. METHODS: 60 porcine front foot tendons were evenly divided into 4 groups. In groups 1 to 3, tendons were transversely lacerated and repaired with grasping points at both ends away from the laceration by 5 mm, 10 mm, and 15 mm respectively. In group 4, tendons were obliquely lacerated and repaired with a grasping point 5 mm away from the laceration on one end and 15 mm on the other. All tendons were repaired with a modified 4-strand core suture and continuous epitendinous suture, and then tested to failure in a tensile machine. RESULTS: The tensile strength in group 1 was significantly lower than that in the other 3 groups (p<0.005). The tensile strength in group 4 was not significantly different from groups 2 and 3. CONCLUSION: The tensile strength of modified 4-strand cruciate repair configuration is not weakened in obliquely lacerated tendons; the grasping point at one end of the tendon being 15 mm away from laceration provides sufficient strength to compensate for the relatively weak 5-mm end. So long as one grasping point is away from the laceration site by 10 mm, the ultimate tensile strength of the transversely lacerated tendons appears acceptable. The modified 4-strand cruciate repair is safe to use for repairing obliquely lacerated tendons.     

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.