Reattachment of flexor digitorum profundus avulsion: biomechanical performance of 3 techniques

A Meta-Analysis of Biomechanical Studies for Suture Button Pullout Versus Suture Anchor Repair of Flexor Digitorum Profundus Avulsions

BACKGROUND

There is no current consensus on which of the two most common flexor digitorum profundus (FDP) avulsion repair constructs, via suture button pullout (SBP) or suture anchor (SA), is biomechanically superior. Our purpose was to compare these repair methods via systematic review and meta-analysis of available literature.

METHODS

We performed a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic review of PubMed, the Cochrane library, and Embase. We only included studies with direct comparison data for both techniques. We performed a meta-analysis comparing the reported biomechanical results using pooled data for initial repair stiffness (N/mm), gap formation (mm), and ultimate load to failure (N).

RESULTS

Seven studies met inclusion criteria, including a total of 201 cadaveric specimens. Four studies reported initial construct stiffness, with pooled analysis showing superiority for SA repairs (P < .05). Four studies evaluated gap formation, with pooled analysis demonstrating less gapping with SA repair (P < .05). Mean gap formation was 2.4 (±1.4) mm and 3.9 (±2.0) mm for the SA and SBP groups, respectively. All 7 studies assessed load to failure, with pooled analysis revealing no significant difference between groups (P > .05). We lacked statistical power to determine equivalence between techniques for load to failure. Both groups had failure values significantly lower than the native FDP.

CONCLUSIONS

Via meta-analysis, there was increased initial construct stiffness and less gap formation for SA compared to SBP for FDP reinsertion, with no significant differences for ultimate failure load.

All-Suture Anchor Repair of the Flexor Digitorum Profundus Insertion: A Biomechanical Comparison of 2 Suturing Techniques

PURPOSE

We compared 2 suturing techniques for reattachment of the flexor digitorum profundus (FDP) via all-suture anchor.

METHODS

We used fresh, matched-pair, cadaveric hands. We disarticulated the fingers at the proximal interphalangeal joints, preserving the proximal FDP. We released the FDPs at their distal insertion and placed an all-suture, 1.0-mm anchor at the center of each FDP footprint. Each anchor's sutures were used to reattach each FDP using 1 of 2 techniques: group H (n = 14) via horizontal mattress; group H + K (n = 12) via horizontal mattress with knots thrown and, with each suture tail, 3 proximal, running-locking, Krackow-type passes on the radial and ulnar FDP sides with the suture ends tied together. We excluded 2 specimens from the H + K group because of improper anchor placement. All other fingers in both groups were individually mounted in an MTS machine for FDP loading in the following sequence for 500 cycles each: (1) to 15 N to simulate passive motion forces; (2) to 19 N for short-arc active motion forces; and (3) to 28 N for full active motion forces. Specimens that had not failed during cyclic testing were then loaded to failure. We measured FDP-to-bone gapping via a digital transducer. We defined failure as >3-mm gapping.

RESULTS

The H + K group had significantly less gapping during cyclic loading up to 19 N and significantly higher load to failure. The H + K group failed exclusively at the anchor-bone level; the H group failed mostly by suture-tendon pullout.

CONCLUSIONS

The H + K group performed significantly better regarding cyclic and load-to-failure testing after FDP reattachment.

CLINICAL RELEVANCE

The H + K technique combines the benefits of horizontal-mattress tendon-to-bone apposition and Krackow-tendon locking. It converts the point of failure to the bone level rather than the suture-tendon level.

The Transosseous Internal Four Strand Technique: A New All-Inside Technique for Zone 1 Flexor Tendon Repairs

BACKGROUND

Multiple techniques for the repair of flexor tendon injuries in zone 1 have been proposed over time. While pull-out suture techniques and bone anchor seem to be stronger than internal suture techniques, they are associated with a higher complication rate. We therefore developed an alternative internal suture repair with similar biomechanical stability to those of pull-out sutures and bone anchors.

METHODS

Twenty porcine distal phalanges and deep flexor tendons were randomized to 2 groups of 10 each. The tendons were transsected at the level of the distal interphalangeal joint. In group 1, repairs were performed with a well-established intraosseous suture repair and in group 2 with our new multistrand technique. The repairs were biomechanically tested with linear distraction until failure.

RESULTS

We recorded a significantly higher 2-mm gap force (2GF)-and thus higher stability-of the repairs in group 1 in comparison to group 2. With a 2GF of more than 50 N, our suture technique allows for a modern early active motion rehabilitation protocol. Breakage of the suture construct occurred at random places in the repair in both groups. No pull-outs were noted.

CONCLUSIONS

This study presents a strong transosseous multistrand repair technique for flexor tendon repair in zone 1 that is simple and fast to perform and should have enough strength to withstand early active motion rehabilitation.

A suture anchor-based repair technique for type IV jersey finger injuries: a biomechanical investigation

The aim of this biomechanical investigation was to evaluate a repair technique for type IV FDP tendon avulsions using a suture anchor, addressing the bony and the tendinous aspect of this injury simultaneously. In 45 distal phalanges from human anatomical specimens the injury was simulated and repairs were performed with a suture anchor using an innovative technique, interosseous sutures and a combination of screws and an interosseous suture. Repetitive loading for 500 cycles simulated postoperative mobilization. Repairs were loaded to failure thereafter. Elongation of the tendon-suture complex, gap formation at the bone-bone contact line and at the bone-tendon insertion line, load at first noteworthy displacement (2 mm), load at failure and the mechanism of failure were assessed. The suture anchor technique was superior biomechanically considering load at failure (mean: 72.8 N), bony gap formation (mean: 0.1 mm) as well as tendinous gap formation (mean: 0.7 mm), implying a preferable stability of the repair. Overall, this study demonstrates good ex vivo mechanical stability for a proposed suture anchor repair technique for type IV FDP tendon avulsion injuries, which might enable early postoperative mobilization in patients. The technique's subcutaneous implant placement and low implant load are expected to reduce potential complications observed in other commonly used repair techniques. This approach warrants further evaluation in vivo.

The Evaluation of a Flexor Digitorum Profundus-to-Volar Plate Zone I Repair Versus Button Repair: An In vitro Biomechanics Study

PURPOSE

The purpose of the study was to evaluate joint kinematics and tendon work of flexion (WOF) following a flexor digitorum profundus (FDP)-to-volar plate (VP) repair technique relative to a pullout button for zone I flexor tendon injuries.

METHODS

Fourteen digits were tested using an in vitro active finger motion simulator under 3 repaired conditions following a simulated zone I avulsion: button, FDP-VP, and "no slack" FDP-VP (corrected for additional VP length). Outcome metrics included active joint range of motion (ROM), fingertip strength, FDP and flexor digitorum superficialis tensile loads, and WOF.

RESULTS

The button and FDP-VP techniques restored WOF to the intact condition for FDP and flexor digitorum superficialis. All repairs restored distal interphalangeal joint ROM and kinematics to the intact condition. Similarly, all repairs restored WOF; however, the "no slack" FDP-VP significantly increased WOF by 10% to 12% over the simple FDP-VP repair. The button technique had similar fingertip strength to the intact condition, whereas the FDP-VP repairs significantly reduced peak fingertip strength from intact, albeit only 1-2 N compared with the button repair.

CONCLUSION

In this in vitro cadaveric model, the button and FDP-VP techniques restored WOF and ROM to within intact levels, with no difference between these repairs in all measured outcome metrics.

CLINICAL RELEVANCE

Based on its initial strength and its equal biomechanical performance compared with the button repair, the FDP-VP technique may be a viable option for treating FDP avulsions.

Hook Plate as a Treatment for Flexor Digitorum Profundus Avulsion Types II and III

Avulsion fracture types II and III of flexor digitorum profundus (FPD), also called Jersey Finger, in flexor zone 1 are an uncommon pathology requiring surgical treatment. The aim of this study was to assess whether hook miniplates were an accessible and reliable option to repair FDP avulsion types II and III. Between July and August 2018, we treated 2 consecutive patients' zone 1 Leddy-Packer type II and III FDP injuries with hook plates and 1.2 × 7 mm screws included in Medartis Aptus Hand fixation system set. Patients were aged 37 and 39 years, a man and a woman, respectively. At the end of the follow-up, we evaluated the Visual Analog Scale, range of motion, grip strength, and Quick Disabilities of the Arm, Shoulder, and Hand. Both patients completed 12 months of follow-up with excellent functional and radiological results. Neither presented complications or residual disability. This injury has been treated with a wide range of surgical techniques, including anchor suture, pullout button sutures, screws, and plates. However, due to the difficulty in surgical fixation of fragments around finger joints, limited access to ligaments and tendons, and the lack of cases, none of the techniques have turned out as a clear option above others. Hook plates placed in distal phalanx emerge as surgical treatment for FDP avulsion types II and III in flexor zone 1, with excellent clinical outcomes.

Transosseous Sutures in Tendon-to-Bone Repairs: the Role of the Epitendinous Suture

BACKGROUND

Numerous transosseous fixation techniques for flexor tendon injuries in Zone 1 of the hand have been described in the literature. While relatively high maximal loads to failure are documented in different biomechanical experiments, several tests revealed a low 2 mm gapping resistance of the tendon-to-bone repairs. We therefore aimed to investigate the effect on gap formation adding a peripheral suture to an established transosseous fixation technique. In addition, we analyzed the influence of different suture materials (braided vs. non-braided) on the stability of the core suture.

METHOD

A total of 30 porcine flexor digitorum profundus tendons were divided into 3 groups (n = 10 each) and repaired using the transverse intraosseous loop technique (TILT). In group 1 and group 2 the repairs were performed using PDS 3-0 or Ethibond 3-0, respectively. In group 3, a peripheral suture was added to the core suture (PDS 3-0) consisting of two figure-of-eight stitches with PDS 5-0. The biomechanical performance of the repaired tendons was analyzed using a standardized protocol.

RESULTS

The suture material and peripheral suture showed no effect on the ultimate failure load in our testing. However, the addition of a peripheral suture led to a statistically significantly higher 2 mm gap force when compared with the repair with a core suture only.

CONCLUSION

In conclusion, addition of a palmar epitendinous suture to the transosseous core suture significantly increases the load to 2 mm gap formation in Zone 1 flexor tendon repairs and thus allows an immediate controlled mobilization.

Biomechanical Comparison of Flexor Digitorum Profundus Avulsion Repair

Purpose  Multiple repair techniques have been investigated for flexor digitorum profundus (FDP) tendon avulsions. The purpose of this study is to compare the biomechanical characteristics of a new fully threaded titanium suture anchor with previously examined fixation techniques. Methods  Repair of FDP tendon avulsions was performed in 18 fresh-frozen cadavers using one of three implants: Nano Corkscrew FT 1.7 mm suture anchor (Group 1; Arthrex, Inc., Naples, FL; n  = 6), Mitek Micro 1.3 mm suture anchor (Group 2; Mitek Surgical Products, Westwood, MA; n  = 6), or pullout suture button fixation (Group 3; n  = 6). Constructs were preloaded before testing load to failure. For each trial, elongation at 20 N and maximum load, mean load to failure, stiffness, and failure mechanism were recorded. Results  Load to failure occurred in all trials. Mean load to failure was significantly greater for Group 1 (61.6 ± 18.9 N) compared to Group 2 (42.5 ± 4.2 N; p  < 0.05) and Group 3 (41.6 N ± 8.0 N; p  < 0.05). Stiffness was significantly greater in Groups 1 and 2 compared to Group 3 (6.9 ± 2.2 N/mm vs. 6.1 ± 0.8 N/mm vs. 3.1 N/mm ± 0.5 N/mm, respectively, p  < 0.01). Mechanism of failure differed between the groups: Group 1 broke at the anchor in two trials and tore through the tendon in three trials, Group 2's suture universally broke at the anchor, and Group 3's trials mainly failed at the button. Conclusions  The Nano Corkscrew anchor (Group 1) has a significantly higher load to failure when compared with the other techniques. The higher load to failure of the corkscrew anchor provides a secure method for flexor tendon repair in zone I. Clinical Relevance  A fully threaded titanium suture anchor used for FDP tendon avulsion injuries is likely to withstand early active range of motion protocols.

A review of mallet finger and jersey finger injuries in the athlete

PURPOSE OF REVIEW

The purposes of this review are to discuss the diagnosis and management of mallet and jersey finger injuries in athletes and to highlight how treatment impacts return to play.

RECENT FINDINGS

Mallet finger: although numerous non-operative and operative techniques have been described, there continues to be little consensus regarding the optimal procedure. Jersey finger: ultrasound appears to be a cost-effective imaging modality that may be useful for preoperative planning. Wide-awake surgery offers optimal intraoperative assessment of the tendon repair. Tendon repair with volar plate augmentation has been shown to improve the strength of the repair in the laboratory, and early clinical results are encouraging. Most mallet finger injuries will heal with non-operative treatment over a period of 8-12 weeks, even when treatment is delayed up to 3-4 months. An acute diagnosis of jersey finger requires surgical treatment and generally means 8-12 weeks of inability to compete in most contact sports.

Use of the Volar Plate of the Distal Interphalangeal Joint as a Distally Based Flap in Flexor Tendon Surgery

The usual treatment for flexor digitorum profundus (FDP) avulsions as well as FDP lacerations in the distal part of zone I is tendon reinsertion into bone. Although there are several different techniques of FDP tendon reinsertion into bone, they are generally complex and have a weak tensile strength. A technique for treating these injuries is to use the volar plate of the distal interphalangeal joint as a distally based flap for tendon repair. The current communication discusses the technique and its potential complications. Initial clinical experience is encouraging and the volar plate flap technique may take its place in flexor tendon surgery.