Early active mobilization of tendon grafts using mesh reinforced suture techniques

Flexor Tendon Grafting Using Extrasynovial Tendons Followed by Early Active Mobilization

Purpose

This study evaluated the outcomes of early active mobilization after flexor tendon grafts using extrasynovial tendons with a novel distal fixation technique.

Methods

This study was a retrospective case series. The flexor digitorum profundus (FDP) tendons of 7 digits in 7 patients were reconstructed with extrasynovial tendons, which included the palmaris longs, plantaris, and extensor digitorum longus, in a single- or 2-stage procedure between 2008 and 2017. Of the 7 patients, 6 were male and the average patient age was 48 years. The injuries involved 2 middle, 2 ring, and 3 little fingers. The tendons were sutured into the appropriate FDP tendon proximally using end-weave anastomosis; the distal end of the graft was fixed to the distal stump of the FDP using an interlacing suture or a small bone anchor combined with the pull-through technique. The digits were mobilized with a combination of active extension and passive and active flexion in a protective orthosis during the first 6 weeks after surgery. Average follow-up was 18 months. We measured active and passive digit motion both before tendon grafting and at the final evaluation. Outcomes were graded by the LaSalle formula to assess staged flexor tendon reconstruction.

Results

Average passive range of motion (ROM) of the proximal and distal interphalangeal joints before flexor tendon grafting was 146° (SD, 22°). Mean active ROM of these joints at the final evaluation was 123° (SD, 34°). Using the LaSalle formula, mean recovery of active motion was 83%. We encountered no grafted tendon rupture and no finger required tenolysis.

Conclusions

Our proximal and distal fixation techniques allowed the autologous extrasynovial tendon grafts to withstand the stress encountered during early active mobilization with good postoperative ROM and minimal complications.

Type of study/level of evidence

Therapeutic I.

Tensile strength of a weave tendon suture using tendons of different sizes

BACKGROUND

This study compared the maximum load, stress, elongation at failure and the mode of failure of three kinds of tendons most frequently used for tendon grafting and tendon transfers, using the Pulvertaft weave suture.

METHODS

Sixty tendons were used from fresh human cadaver upper and lower extremities. The performed repairs included: 9 specimens of flexor digitorum superficialis or profundus tendon with flexor digitorum superficialis or profundus tendon (thick-thick suture), 10 specimens of flexor digitorum superficialis or profundus tendon with palmaris longus tendon (thick-medium thin suture), and 10 specimens of flexor digitorum superficialis or profundus tendon with plantaris tendon (thick-thin suture). Material testing machine was used to test repairs to failure.

FINDINGS

The mean maximum load at failure increased with the thickness of donor tendon. For the thick-thick specimen, the maximum load at failure was 125 newtons (N), for the thick-medium thin specimen it was 86,8N, and for the thick-thin it was 65,2N. These differences were all statistically significant.

INTERPRETATION

The active rehabilitation protocol is possible only with thick-thick connections used, the strength of the thick-medium thin connection is on the border of indications for the active rehabilitation protocol, and the thick-thin connection strength is sufficient only for the passive rehabilitation protocol.

Carbodiimide-derivatized hyaluronic acid surface modification of lyophilized flexor tendon: a biomechanical study in a canine in vitro model

BACKGROUND

Intrasynovial grafts are the ideal solution to replace defects in intrasynovial flexor tendons, but autologous graft sources are rarely available. The purpose of the present study was to test the hypotheses that an intrasynovial tendon prepared with repetitive freeze-thaw cycles and lyophilization (as a means of reducing immunogenicity) has increased frictional force (gliding resistance) in comparison with fresh intrasynovial tendons and that a lyophilized intrasynovial flexor tendon that is modified with carbodiimide-derivatized hyaluronic acid and gelatin has decreased frictional force in comparison with untreated lyophilized tendons.

METHODS

Thirty-six flexor digitorum profundus tendons from the second and fifth digits of canine hind paws were randomly assigned to three groups. Twelve tendons were immediately assessed both mechanically and morphologically and served as the normal tendon group. The other twenty-four tendons were prepared with repetitive freeze-thaw cycles and lyophilization and were randomly assigned to two groups, including one group in which the tendons were treated with carbodiimide-derivatized hyaluronic acid and gelatin and one group in which the tendons were not treated. The frictional force was measured during 1000 cycles of simulated flexion-extension motion in all tendons, and the mean frictional forces were compared. The tendons were then observed with use of transmitted light microscopy for residual hyaluronic acid on the tendon surface, and the smoothness of the surface was evaluated with use of scanning electron microscopy.

RESULTS

The frictional force after lyophilization was significantly increased by 104.9% after the first cycle and by 99.5% after 1000 cycles in comparison with the normal tendon (p < 0.05). The frictional force of the lyophilized tendons after treatment with carbodiimide-derivatized hyaluronic acid and gelatin was not significantly different from that of normal tendons. The untreated lyophilized tendon surfaces were observed on scanning electron microscopy to be rough in appearance, whereas the normal surface and the surface treated with carbodiimide-derivatized hyaluronic acid and gelatin were smooth, with residual hyaluronic acid present on the gliding surface.

CONCLUSIONS

Lyophilization alters tendon surface morphology and increases tendon frictional force. Surface modification with carbodiimide-derivatized hyaluronic acid and gelatin can mitigate this adverse effect.

CLINICAL RELEVANCE

Tendon surface modification with carbodiimide-derivatized hyaluronic acid and gelatin can improve the gliding ability of lyophilized flexor tendons and therefore may improve the utility of lyophilized tendon allografts as a tendon graft substitute.

Zone 2 flexor tendon repair in young children: a comparative study of four-strand versus two-strand repair

This study compares the active ranges of finger motion and rupture rates of two-strand and four-strand repairs in zone 2 flexor tendon lacerations in young children. A total of 29 patients (under the age of 4 years) with 32 flexor tendon lacerations in zone 2 were evaluated. The injured tendons were randomly repaired with either two-strand or four-strand modified Strickland techniques. At a mean follow-up period of 11 months, the mean total active motion of interphalangeal joints was 156 degrees in the two-strand and 158 degrees in the four-strand group. According to the Strickland original method, this means an average of 89% (range 57-100%) of normal function in the two-strand and 90% (range 60-100%) in the four-strand group. There were no ruptures of the four-strand repairs, but one two-strand repair failed within 3 weeks of the repair. Statistically, we were not able to show any significant difference in the active ranges of finger motion achieved with two-strand and four-strand repairs.

The effect of carbodiimide-derivatized hyaluronic acid and gelatin surface modification on peroneus longus tendon graft in a short-term canine model in vivo

PURPOSE

We have recently reported that application of carbodiimide-derivatized hyaluronic acid and gelatin (cd-HA gelatin) to a peroneus longus tendon graft increased tendon graft gliding ability and decreased work of flexion compared with untreated grafts in a canine model in vivo. In this study, we investigated the effect of this modification on adhesions, stiffness, strength of the distal attachment, and fibroblast count.

METHODS

A total of 24 dogs were used for this study. The peroneus longus tendons of each hind leg were grafted into the 2nd and 5th digits of one forepaw in each dog. One peroneus longus tendon was treated with cd-HA gelatin prior to grafting, and the other one was immersed in 0.9% saline solution as a control. Animals were killed 1, 3, or 6 weeks postoperatively.

RESULTS

The adhesion score of cd-HA gelatin-treated tendons was significantly less than that in the saline-treated tendons at all time points. There was no significant difference in the indentation stiffness between HA- and saline-treated grafts at any time point. For the ultimate force at the distal attachment, there was a significant difference among the time points, with a steady increase over time, but no significant difference between treated and control tendons at any time point. There was no significant difference in fibroblast count between treated and control tendons at any time point.

CONCLUSIONS

Although gross adhesion formation was less, there was no significant difference in strength at the distal tendon-bone interface, cellularity, or tendon graft stiffness when comparing saline-treated and cd-HA gelatin-treated tendon grafts in vivo.

Surface treatment of flexor tendon autografts with carbodiimide-derivatized hyaluronic Acid. An in vivo canine model

BACKGROUND

Clinical and experimental studies have demonstrated that restrictive adhesions and poor digital motion are common complications after extrasynovial tendon grafting in an intrasynovial environment. The purpose of this study was to test the hypothesis that surface modification of an extrasynovial tendon with use of a carbodiimide-derivatized hyaluronic acid-gelatin polymer (cd-HA) improves gliding ability and digital function after tendon grafting in a canine model in vivo.

METHODS

The peroneus longus tendons from both hindpaws of twenty-four dogs were harvested and transplanted to replace the flexor digitorum profundus tendons in the second and fifth digits of one forepaw. Prior to grafting, one of the peroneus longus tendons was coated with cd-HA, which consists of 1% hyaluronic acid, 10% gelatin, 0.25% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), and 0.25% N-hydroxysuccinimide (NHS), while the other was immersed in saline solution only. Eight dogs were killed at one, three, and six weeks. Digital normalized work of flexion, tendon gliding resistance, and hyaluronic acid quantification (with the hyaluronic acid-binding-protein staining technique) were the outcome measures.

RESULTS

The normalized work of flexion of the tendons treated with cd-HA was significantly lower than that of the saline-solution-treated controls at each time-point (p < 0.05). The gliding resistance of the cd-HA group was significantly lower than that of the saline-solution group at three and six weeks (p < 0.05). The ratio between the intensity of staining of the cd-HA-treated tendons with that of the saline-solution-treated controls was significantly greater at time-0 than at three or six weeks (p < 0.05), but there was no significant difference between time-0 and one-week values.

CONCLUSIONS

Treating the surface of an extrasynovial tendon autograft with a carbodiimide-derivatized hyaluronic acid-gelatin polymer decreases digital work of flexion and tendon gliding resistance in this flexor tendon graft model in vivo.

CLINICAL RELEVANCE

cd-HA gelatin may provide surgeons with a new and useful method to improve the quality of tendon graft surgery.

Effect of gap size on gliding resistance after flexor tendon repair

BACKGROUND

Gap formation is a common complication after flexor tendon repair and is associated with adhesion formation, tendon rupture, and decreased strength. The purpose of this study was to investigate the effect of gap formation on tendon gliding resistance after flexor tendon repair in a human cadaver model.

METHODS

Twelve index, middle, and ring fingers from four adult human cadaveric hands were used. Gliding resistance versus excursion between the flexor digitorum profundus tendon and the A2 pulley was first measured in intact tendons. After full laceration, each tendon was repaired with the Pennington suture technique and the gliding resistance was measured again. Then, the repaired tendon (a 0-mm gap) was stretched to form a 1-mm gap, and gliding resistance was remeasured. A magnified video image was used to monitor gap size. This process was repeated to evaluate gap sizes of 2, 3, and 4 mm at the repair site. Peak gliding resistance was determined, and the peak gliding resistance was compared among the groups.

RESULTS

No significant difference in peak gliding resistance was detected between repaired tendons without a gap and tendons with a 1-mm gap. Repaired tendons with a 2-mm gap could pass through the A2 pulley; however, peak gliding resistance was significantly higher than that for tendons with a 0 or a 1-mm gap (p < 0.05). When the gap reached > or =3 mm, all tendons caught at the A2 pulley edge, causing a dramatically increased peak gliding resistance.

CONCLUSIONS

The presence of a 2-mm gap after flexor tendon repair significantly increased tendon peak gliding resistance (p < 0.05), while a gap of > or =3 mm further increased peak gliding resistance because of catching at the pulley edge.

Flexor tendon graft attachment: a review of methods and a newly modified tendon graft attachment

A review of the described methods of attachment of flexor tendon grafts to the distal phalanx is presented. The authors advocate the previously described method of attachment consisting of passage of the tendon graft through the pulp with anchorage to the nail. A new modification of this technique is presented, facilitating accurate dissection and placement of the graft with minimal trauma.

The strength of distal fixation of flexor digitorum profundus tendon grafts in human cadavers

Early active motion limits adhesion formation and thus improves functional performance after tendon grafting. The early strength of distal fixation is critical to successful tendon grafting. We describe a new Y-tunnel technique of distal fixation and compare it with 2 established methods, the Pulvertaft transverse tunnel and the Bunnell button over the fingernail techniques, in a human cadaver model to determine which is the strongest method. Hands with a grafted tendon were rigidly mounted on an anatomic tensiometer testing apparatus and loaded to failure. Mean load to failure (newtons +/- 95% confidence intervals) of the Y-tunnel technique (155.2 +/- 29.4) was greater than those for the Pulvertaft (100.2 +/- 13.2) and Bunnell (57.1 +/- 4.7) techniques. Two-way analysis of variance showed significant differences, and the Bonferroni multiple pairwise comparison test showed that all 3 intergroup comparisons were statistically significant. These results indicate marked improvement in immediate strength with the Y-tunnel technique and lay the groundwork for further studies using a healing tendon model.

Wrist and digital joint motion produce unique flexor tendon force and excursion in the canine forelimb

The force and excursion within the canine digital flexor tendons were measured during passive joint manipulations that simulate those used during rehabilitation after flexor tendon repair and during active muscle contraction, simulating the active rehabilitation protocol. Tendon force was measured using a small buckle placed upon the tendon while excursion was measured using a suture marker and video analysis method. Passive finger motion imposed with the wrist flexed resulted in dramatically lower tendon force (approximately 5 N) compared to passive motion imposed with the wrist extended (approximately 17 N). Lower excursions were seen at the level of the proximal interphalangeal joint with the wrist flexed (approximately 1.5 mm) while high excursion was observed when the wrist was extended or when synergistic finger and wrist motion were imposed (approximately 3.5 mm). Bivariate discriminant analysis of both force and excursion data revealed a natural clustering of the data into three general mechanical paradigms. With the wrist extended and with either one finger or four fingers manipulated, tendons experienced high loads of approximately 1500 g and high excursions of approximately 3.5 mm. In contrast, the same manipulations performed with the wrist flexed resulted in low tendon forces (4-8 N) and low tendon excursions of approximately 1.5 mm. Synergistic wrist and finger manipulation provided the third paradigm where tendon force was relatively low (approximately 4 N) but excursion was as high as those seen in the groups which were manipulated with the wrist extended. Active muscle contraction produced a modest tendon excursion (approximately 1 mm) and high or low tendon force with the wrist extended or flexed, respectively. These data provide the basis for experimentally testable hypotheses with regard to the factors that most significantly affect functional recovery after digital flexor tendon injury and define the normal mechanical operating characteristics of these tendons.

Capsular replacement with synthetic mesh: effectiveness in preventing postoperative dislocation after wide resection of proximal femoral tumors and prosthetic reconstruction

We describe a surgical technique for replacing the hip joint capsule using synthetic mesh after oncological resections of the proximal femur that resulted in gross intraoperative instability of the prosthetic reconstruction. The results of its use in 13 patients, 6 of whom also had pelvic resections, are described. These patients were selected from a total group of 88 patients undergoing proximal femoral replacement, 75 of whom did not require capsular replacement (none of these 75 patients have experienced dislocation). In the group requiring capsular reconstruction, 1 of 4 patients with bipolar hemiarthroplasty and 4 of 9 patients with total hip replacements experienced dislocation after operation. Of the dislocated total hip replacements, 1 remains chronically dislocated, and 3 were successfully stabilized by open reduction with further capsular augmentation. Given that the resections involved removal of most of the soft tissues stabilizing the hip joint, we believe that the technique of capsular reconstruction is useful in this difficult group of patients.

Controlled active motion following primary flexor tendon repair: a prospective study over 9 years

One hundred and thirty patients with 339 divided flexor tendons affecting 208 fingers were studied prospectively between 1988 and 1996, to assess a regime of primary flexor tendon suture and active postoperative motion, combined with a modified Kleinert dynamic traction splint. The tendon suture technique used was a high-strength multistrand technique using a modified Kessler core and a Halsted peripheral stitch. The results were influenced by the zone in which the tendon was divided, by the physiotherapy and to a lesser extent by the grade of surgeon operating. Overall results by Strickland criteria were 92% excellent or good, 7% fair and 1% poor. There were 43 complications in 31 patients including five zone 2 ruptures (5.7%) and one further rupture in zone 5. This method of flexor tendon repair requires good physiotherapy and splint-making capability but gives good results with minimal need for further surgery.