Flexor Digitorum Profundus Tendon Repair Research Articles

Outcomes of Acute Repair Versus Nonrepair of Zone I Flexor Digitorum Profundus Tendon Injuries

The aim of this study was to determine whether the clinical results of zone I flexor digitorum profundus (FDP) tendon injuries managed with acute surgical repair are comparable to the clinical results of those managed without repair (eg, primary FDP excision or observation). Patients aged ≥18 years presenting to a level 1 trauma center between 2015 and 2020 with zone I FDP tendon injury were identified with retrospective chart review. We assessed the following data: age, sex, physical therapy visits, surgical intervention, surgical complications (including infection, repeat surgery after the primary intervention, and rupture of repair), and patient-reported outcomes measurement information system scores. Twenty-six patients met the inclusion criteria. Group 1 (N= 15 patients, 23 fingers) patients were treated with acute surgical repair. Group 2 (N= 11 patients, 11 fingers) patients were managed without surgical repair, including FDP excision (N= 7) or observation alone (N= 4). In group 1, the average distance from the distal palmar crease to fingertip at the final follow-up was 1.6 cm (range, 0-4 cm). Fourteen of the 15 patients participated in >3 therapy visits. The following complications occurred: 4 fingers with rerupture (2 patients), 4 fingers with surgical wound dehiscence (2 patients), 3 infections (2 patients), and 4 repeat surgeries for these complications. In group 2, the average distance from the distal palmar crease to fingertip at the final follow-up was 1.1 cm (range, 0.5-3 cm). There were no infections, episodes of wound dehiscence, or repeat surgeries. At the final follow-up, both groups showed clinically meaningful improvement on Patient Reported Outcomes Measurement Information System (PROMIS) upper extremity, pain interference, and physical function scores, with similar PROMIS domain scores between groups. Patients treated without FDP tendon repair had similar outcomes to, and fewer complications than, patients treated with acute tendon repair. Our data suggest that the notable commitment of health care costs, time, and adherence to protocols/restrictions after surgical repair may not confer functional benefit. Therapeutic IV.

Comparative Sensitivity and Specificity of Static and Dynamic High-Resolution Ultrasound in Diagnosis of Small Gaps in Repaired Flexor Tendons: A Cadaveric Study

To compare the sensitivity and specificity of high-resolution static and dynamic ultrasound (US) for diagnosing intact repairs and small, clinically relevant gaps (≥4 mm) in repaired flexor digitorum profundus tendons within zone 2 and, secondarily, to evaluate the effect of suture artifact from 3 commonly used suture types. Eighty-eight fresh-frozen cadaveric digits (thumbs excluded) were randomized to either an intact repair (0-mm gap) or repairs using a locked 4-strand suture repair with either 4-0 Prolene, Ethibond, or FiberWire and gaps of 2, 4, or 6 mm and no suture in which 2-, 4-, or 6-mm gaps were created without a suture crossing the repair site. Gap widths were estimated by a blinded musculoskeletal ultrasonographer in static and dynamic modes. Both static and dynamic modalities tended to overestimate actual gap sizes. For the suture gaps, both modalities had poor sensitivity (29% static; 42% dynamic) for accurately diagnosing a clinically intact repair (<4 mm), but better specificity (83% static; 75% dynamic) for diagnosing a clinically failed repair (≥4-mm gap). Although suture presence decreased the sensitivity of gap width measurement for both modalities, no differences were seen between suture types. Static and dynamic US have poor sensitivity for diagnosing clinically intact repairs (gaps < 4 mm) because they typically overestimate gap size. The ability to diagnose failed repairs (gap ≥ 4 mm), based on greater specificity, is much better, but still suboptimal. Based on a receiver operating characteristic analysis cutoff of 5 mm, if a gap of 5 mm or larger is identified with US when evaluating a zone 2 flexor digitorum profundus tendon repair, a failed repair is likely in about 80% of cases. A gap measurement of less than 5 mm may miss a high percentage of repairs that are clinically failed.

A novel engineered purified exosome product patch for tendon healing: An explant in an ex vivo model.

Reducing tendon failure after repair remains a challenge due to its poor intrinsic healing ability. The purpose of this study is to investigate the effect of a novel tissue-engineered purified exosome product (PEP) patch on tendon healing in a canine ex vivo model. Lacerated flexor digitorum profundus (FDP) tendons from three canines' paws underwent simulated repair with Tisseel patch alone or biopotentiated with PEP. For the ex vivo model, FDP tendons were randomly divided into three groups: FDP tendon repair alone group (Control), Tisseel patch alone group, and the Tisseel plus PEP (TEPEP) patch group. Following 4 weeks of tissue culture, the failure load, stiffness, histology, and gene expression of the healing tendon were evaluated. Transmission electron microscopy revealed that in exosomes of PEP the diameters ranged from 93.70 to 124.65 nm, and the patch release test showed this TEPEP patch could stably release the extracellular vesicle over 2 weeks. The failure strength of the tendon in the TEPEP patch group was significantly higher than that of the Control group and Tisseel alone group. The results of histology showed that the TEPEP patch group had the smallest healing gap and the largest number of fibroblasts on the surface of the injured tendon. Quantitative reverse transcription polymerase chain reaction showed that TEPEP patch increased the expression of collagen type III, matrix metallopeptidase 2 (MMP2), MMP3, MMP14, and reduced the expression of transforming growth factor β1, interleukin 6. This study shows that the TEPEP patch could promote tendon repair by reducing gap formation and inflammatory response, increasing the activity of endogenous cells, and formation of type III collagen.

Short-term Assessment of Optimal Timing for Postoperative Rehabilitation after Flexor Digitorum Profundus Tendon Repair in a Canine Model

The purpose of this study was to compare the short-term outcome following flexor tendon repair for postoperative rehabilitation commencing on day 1 (a common clinical choice) versus day 5 (the day on which, with postoperative immobilization, the initial gliding resistance is least in this model) in an in vivo canine model. Work of flexion (WOF) and tendon strength were evaluated following tendon laceration and repair in 24 dogs sacrificed 10 days postoperatively. Starting postoperative mobilization at day 5 resulted in no tendon ruptures compared with tendon ruptures in four of the dogs (33%) in the group subjected to mobilization starting at day 1. While there was no statistically significant difference in WOF between groups at day 10, there was a trend toward lower resistance favoring the day 5 start group, and the statistical power to detect a difference in WOF was diminished by the ruptures in the day 1 group. We conclude that starting rehabilitation on day 5, when initial gliding resistance is lower, may have an advantage over earlier starting times, when surgical edema and other factors increase the initial force requirements to initiate tendon gliding. We plan further studies to evaluate the longer-term benefits of this rehabilitation program.

Digital Resistance and Tendon Strength During the First Week After Flexor Digitorum Profundus Tendon Repair in a Canine Model In Vivo

After flexor tendon repair, the strength of the repair and the resistance to digital motion are important considerations in deciding when to initiate postoperative rehabilitation. Our objective was to assess these factors in a short-term in vivo canine model of flexor tendon repair. Forty-eight dogs were randomly allocated to four groups based on the duration of postoperative follow-up (one, three, five, or seven days). In each group, two flexor digitorum profundus tendons of one forepaw were exposed. One tendon (the repair tendon) was sharply transected and repaired with a modified Kessler suture, and the other one (the sham tendon) was simply exposed without laceration. The involved paw was immobilized until the animal was killed on the designated day. Three tendons from each dog, including the repair tendon, the sham tendon, and a control tendon from a corresponding normal digit on the contralateral side, were tested. The mean peak total digital resistance force in the repair group was lowest at five days (p < 0.01 compared with seven days; p > 0.05 compared with one and three days). The mean peak force needed to overcome the internal gliding resistance between the repaired tendon and sheath was significantly higher than that in both the sham and control groups at all time-points (p < 0.001); however, this value was also smallest at five days. There was no significant difference in suture strength at any time-point (p > 0.05). When we evaluated tendon-gliding and suture strength after flexor tendon repair, the least favorable ratio of repair strength to force needed to overcome the resistance to digital motion was noted on Day 7, whereas the best combination of tendon strength and low peak resistance force was noted on Day 5.

Tendon surface modification by chemically modified HA coating after flexor digitorum profundus tendon repair.

Carbodiimide derivatized HA (cd-HA) is less soluble in water than normal HA, and therefore has an increased tissue residence time. The purpose of this study was to study the effect of cd-HA gel on gliding and repair integrity during simulated repetitive motion of a repaired tendon in vitro. A total of 36 flexor digitorum profundus (FDP) tendons from six adult mongrel dogs were used and divided into three groups of control, simple HA, and cd-HA. The gliding resistance between the FDP and the proximal pulley, FDS, and bone was measured before laceration and after modified Kessler technique repair at 1, 5, 10, 50, 100, 200, 300, 400, and 500 cycles. After gliding testing, failure load, tendon stiffness, and resistance to gap formation were measured. The results showed from the first cycle to the 10th cycle, there were no significant differences in gliding resistance between the three testing groups (p > 0.05). From the 50th cycle onwards, the friction was significantly lower in the cd-HA gel group than in the control group (p < 0.05). Neither breaking strength, nor tendon stiffness, nor resistance to gap formation of the repairs were significantly different between the three groups (p > 0.05).

Resection of the flexor digitorum superficialis reduces gliding resistance after zone II flexor digitorum profundus repair in vitro.

The effect of complete or partial resection of the flexor digitorum superficialis (FDS) tendon on the gliding resistance of the flexor digitorum profundus (FDP) tendon after FDP tendon repair was investigated. Twenty-four human FDP tendons were cut to 80% of their transverse section and repaired with a modified Kessler or a Massachusetts General Hospital augmented Becker suture technique. Gliding resistance was measured with the following constructs: intact state, sutured FDP tendon with FDS tendon intact, sutured tendon without FDS tendon, and sutured tendon with one slip of FDS tendon excised. After FDP repair the gliding resistance after modified Kessler repair increased 247% with FDS intact, 132% with one slip of FDS present, and 103% with FDS entirely removed. With a Becker repair, resistance increased 671% compared with normal with the FDS intact, 379% with one slip of the FDS, and 348% without the FDS tendon. Preserving the whole FDS resulted in a significantly larger increase in gliding resistance after FDP repair than did full or partial FDS removal, which were not significantly different from each other. These results suggest that the FDS tendon affects the gliding resistance under the pulley after FDP repair and that partial FDS excision may facilitate gliding of a bulky FDP repair.