The mechanical strength of side-to-side tendon repair with mismatched tendon size and shape

The minimum required overlap length for tendon transfer A biomechanical study on human tendons

In tendon transfer surgeries sufficient stability of the tenorrhaphy is essential. In addition to the choice of a suitable technique, adequate overlap of donor and recipient tendons must be ensured. The aim of this study was to investigate the tensile strength with regard to tendon overlap of a recently published tenorrhaphy, termed Woven-Fridén (WF) tenorrhaphy, which displayed higher tensile strength and lower bulk when compared to the established Pulvertaft technique. For this purpose, WF tenorrhaphies with 1.5 cm, 2 cm, and 3 cm tendon overlap were performed and subsequently tested for different biomechanical properties by tensile testing. Among others, the parameters of ultimate load and stiffness were collected. Native tendons served as controls. A formula was derived to quantify the relation between tendon overlap and ultimate load. We observed that sufficient tensile strength (mean ultimate load of 217 N) is already given with a 2 cm tendon overlap. In addition, with more than 3 cm overlap length only little additional tensile strength is to be expected as the calculated ultimate load of 4 cm overlap (397 N) is approaching the plateau of the maximal ultimate load of 435 N (native tendons).

Technique and biomechanical properties of the side-to-side Z-lengthening in spasticity-correcting surgery- a study on porcine tendons

Spasticity-correcting surgery in patients with injuries to upper motor neurons include various techniques, including tenotomies and lengthening of tendons of spastic muscles. Early mobilization including active loading of a lengthened tendon is essential to prevent adhesion formation, which necessitates a lengthening technique that resists the forces produced by the involved muscles. This study on animal tendons reports the biomechanical properties in regards to elongation and load to failure in porcine tendons lengthened by either a 3 or 5 cm overlap and tested in a simple force rig. The lengthening technique used in these tendons is described in step-by-step detail. The mean elongation of 20 lengthened tendons at 100 N was 10 mm for tendons with a 3 cm overlap and 6 mm for tendons with a 5 cm overlap. The mean peak load at failure of the construct was 138 N for lenghened tendons with a 3 cm overlap and 201 N for tendons with a 5 cm overlap. The results of this study indicate that a tendon lengthened by the described technique with a mere overlap of three cm will withstand the estimated forces elicited by muscles in the forearm immediately after surgery.

Pronator teres nerve branch transfer to the extensor carpi radialis brevis nerve branch for wrist extension reconstruction in proximal radial nerve injury following humeral shaft fractures

Background

Tendon and nerve transfers are used for functional reconstruction in cases of proximal radial nerve injury complicated by humeral fractures in patients who do not show functional recovery after primary nerve repair. The effectiveness of pronator teres (PT) nerve branch transfer to the extensor carpi radialis brevis (ERCB) nerve branch for wrist extension reconstruction was investigated and compared to the results of tendon transfer.

Methods

This study included 10 patients with proximal radial nerve injury, who did not show functional recovery after primary nerve repair at our hospital between April 2016 and May 2019. The nerve transfer procedure included PT nerve branch transfer to the ECRB nerve branch to restore wrist extension and the flexor carpi radialis (FCR) nerve branch to the posterior interosseous nerve (PIN) to restore thumb and finger extension. Tendon transfer procedures included PT transfer to the ECRB for wrist extension, FCR transfer to the extensor digitorum communis (EDC) for finger extension and palmaris longus (PL) transfer to the extensor pollicis longus (EPL) for thumb extension.

Results

Five patients recovered Medical Research Council grade M4 muscle strength in the ECRB and EPL in both tendon and nerve groups. Two patients recovered grade M3 strength and three patients recovered grade M4 strength in the EDC in the tendon transfer group, and all five patients recovered grade M4 strength in the EDC in the nerve transfer group. Limited wrist flexion was observed only in one patient in the tendon transfer group.

Conclusion

PT nerve branch transfer to the ECRB nerve branch combined with FCR nerve branch transfer to PIN is a useful strategy for wrist and fingers extension reconstruction in patients with proximal radial nerve injuries.

Teamwork Pays! Ten Tips for a Great Surgeon-Scientist Collaboration

This review represents our summary of what makes a great collaboration between a surgeon and a scientist. At first, with no perspective, such a collaboration seems easy and natural. But as time goes on, with more perspective, you realize how special it is. Now, in our 60s, with approximately 35 years of collaboration and 75 coauthored papers (most of them in The Journal of Hand Surgery), we are thankful and humbled for this tremendously fruitful and, importantly, enjoyable collaboration. We are not so foolish to think that we made this great collaboration-it was a gift. However, we now recognize many characteristics that make it great and have developed the following 10 tips.

Fine tuning of the side-to-side tenorrhaphy: A biomechanical study assessing different side-to-side suture techniques in a porcine tendon model

Recent studies conclude that a new technique for tendon transfers, the side-to-side tenorrhaphy by Fridén (FR) provides higher biomechanical stability than the established standard first described by Pulvertaft (PT). The aim of this study was to optimize side-to-side tenorrhaphies. We compared PT and FR tenorrhaphies as well as a potential improvement, termed Woven-Fridén tenorrhaphy (WF), with regard to biomechanical stability. Our results demonstrate superior biomechanical stability and lower bulk of FR and, in particular, WF over PT tenorrhaphies. The WF and FR technnique therefore seem to be a notable alternative to the established standard tenorrhaphy as they display lower bulk and higher stability, permitting successful immediate active mobilization after surgery.

Outcome from a brachialis donor for wrist extension in tetraplegia-time to reconsider the International Classification for Surgery of the Hand in Tetraplegia (ICSHT)

INTRODUCTION

Surgical reconstruction after quadriplegia represents a powerful solution to restore lost function by injury. A case is presented in which surgical reconstruction of a patient with a C4 level spinal cord injury is performed using the brachialis (BRA) muscle as the donor.

CASE PRESENTATION

The patient previously had no hand function. This transfer, in combination with fusion of the thumb CMC joint and transfer of the flexor pollicis longus (FPL) tendon to the radius, gives the patient full thumb key pinch powered by BRA transferred to the wrist extensors. Theoretical analysis of muscle architectural properties demonstrates that the BRA has sufficient force and excursion to substitute for both the long and short radial wrist extensors. Furthermore, based on the fact that the BRA has almost twice the excursion compared to the extensor carpi radialis longus (ECRL), wrist extension can occur throughout the entire wrist and elbow ranges of motion. Finally, peak tension is lower than the rupture tension previously measured by us using this type of tendon-to-tendon attachment technique, suggesting that the transfer itself is safe and, importantly, can be immediately mobilized for neuromuscular rehabilitation.

DISCUSSION

This procedure can thus restore tremendous functional capacity in patients who were previously categorized as group 0 by the International Classification of Hand Surgery in Tetraplegia (ICSHT). We suggest that, based on the BRA being an excellent donor for surgical reconstruction, that the ICHST system be reconsidered.

The Challenges in restoration of extensor tendons function at the hand

INTRODUCTION

The authors discuss challenges in extensor function restoration at the finger level following distal posterior interosseous or tendon complex injuries, according to the typologies of lesions or the specific patient requirements.

MATERIALS

The authors report on two cases describing challenging resolutions. One patient with EDC lag from zone 6B to 8 requiring FCU prolonged with cadaveric grafts.  One young patient with distal posterior interosseous lesion requiring selective tendon transfers to EPL and EIP to restore selective and autonomous index extension.

RESULTS

In both cases the main goals were obtained, achieving high index of patient satisfaction and excellent outcomes with the restoration of the extension of the fingers.  Conclusions: In distal posterior interosseous nerve lesion, high demanding patients may require selective function to restore fine motor skills, such as autonomous index extension. In extensor tendons loss of substance from zone 6 to 8, involving musculotendinous junction proximally and short remnants distally, by-pass tendon transfer prolonged with cadaveric grafts is required. The authors highlight the techniques available as escape plan according to the necessary solutions.

[Simplified active motion protocol following Extensor indicis to Extensor pollicis longus tendon transfer using a side-to-side suture]

BACKGROUND

Ruptures of the Extensor pollicis longus tendon are commonly treated by Extensor indicis transfer using Pulvertaft suture technique. Current literature does not yet give evidence for a preferable post-operative therapy protocol. A side-to-side suture technique is significantly stronger than the Pulvertaft repair technique and therefore allows an immediate active postoperative treatment. We present a new postoperative protocol, which is simple, fast and safe, and should make treatment easier for patients and therapists.

PATIENTS AND METHODS

We treated 10 patients with a transfer of the extensor indicis tendon between 07/2016 and 08/2017 according to the new active protocol. Patients were seen for follow-up at 2, 4 and 8 weeks. Thumb range of motion, pinch and grip strength as well as subjective parameters like pain and general satisfaction were measured.

RESULTS

All patients regained full function of their thumbs with retropulsion over the level of the palm at 4 weeks. Median pinch strength was 89 % and grip strength 74 % of the contralateral side at week 4. There was no secondary rupture of the reconstructed tendon over a one-year period. All patients were satisfied with the result of the operation and the protocol.

CONCLUSION

Our new active postoperative protocol for extensor indicis transfer using a side-to-side suture has proven to be safe and less strenuous for patients and therapists and has been established as standard treatment in our clinic.

Strength of side-to-side and step-cut repairs in tendon transfers: biomechanical testing of porcine flexor tendons

The aim of the study was to compare side-to-side with step-cut repairs to determine how much of the width it is possible to remove and still keep the repair strong enough to start active mobilization. Porcine flexor tendons were used to create side-to-side, one-third step-cut and half step-cut repairs. There were 15 repairs in each group. The tensile properties of the constructs were measured in a biomechanical testing machine. All repairs failed by the sutures splitting the tendon longitudinally. The maximum load and stiffness were highest in the side-to-side group. Our findings suggest that the half step-cut repair can withstand the forces exerted during active unrestricted movement of the digits in tendons of this size. The advantage of the step-cut repair is reduced bulkiness and less friction, which might compensate for the difference in strength.

Nerve Versus Tendon Transfer for Radial Nerve Paralysis Reconstruction

PURPOSE

With radial nerve lesions, the results of nerve transfers and how they objectively compare with the outcomes of tendon transfers remain unstudied. We compared the results after nerve transfer in patients with less than 12 months since radial nerve injury with the results after tendon transfer in patients not eligible for nerve surgery because of longstanding paralysis (minimum of 15 months).

METHODS

In 14 patients with radial nerve lesions incurred less than 12 months previously, we transferred the anterior interosseous nerve to the nerve of the extensor carpi radialis brevis (ECRB), while the nerve to the flexor carpi radialis was transferred to the posterior interosseous nerve. In 13 patients with lesions of longer duration, we transferred the pronator teres tendon to the ECRB, the flexor carpi ulnaris tendon to the extensor digitorum communis, and the palmaris longus to the rerouted extensor pollicis longus (EPL) tendon. At a final evaluation, we measured passive and active range of motion (ROM) of the wrist, finger, and thumb and grasp strength.

RESULTS

In a comparison of wrist flexion-extension ROM and grasp strength, we observed better recovery in the nerve transfer than in the tendon transfer group. In the tendon transfer group, we observed limitations in wrist flexion in 9 of the 13 patients and permanent radial deviation in 5. Half of the patients in the tendon transfer group needed to flex their wrist to fully extend their fingers, whereas finger extension was possible with the wrist either extended or at neutral in all patients following nerve transfer. After nerve transfer, extension at the first carpometacarpal joint was restored in 11 of the 14 patients, whereas this occurred in just 4 of the 13 patients following tendon transfer. In both groups, we observed a 30° lag in thumb metacarpophalangeal extension, which reflects poor recovery of EPL function.

CONCLUSIONS

Overall, we observed better outcomes in those who underwent nerve transfer versus tendon transfer procedures. However, room still remains for improved thumb motion with both procedures.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

[Postoperative treatment and rehabilitation following flexor tendon injuries]

BACKGROUND

The ideal surgical and postoperative treatment for flexor tendon injuries, especially in zone 2, is still subject to continuous modifications and professional discussions.

OBJECTIVE

Presentation of established rehabilitation concepts, specific problems and new treatment approaches with practical recommendations for application.

MATERIAL AND METHODS

Comparison of commonly used treatment concepts by assessing surgical flexor tendon repair, splint choice and clinical application in patients. Discussion of new surgical approaches and standards and their influence on postoperative therapy after flexor tendon injuries.

RESULTS

The Washington regimen has retained its status as the standard in the current follow-up treatment of flexor tendon injuries. New suture materials and techniques enable early active rehabilitation of sutured flexor tendons with good clinical results, such as increased range of motion for interphalangeal joint extension and improved distal interphalangeal joint flexion with overall acceptable frequencies of suture rupture.

CONCLUSION

A stable tendon repair with smooth gliding is the foundation for treatment after flexor tendon injuries. After intraoperative active digital extension-flexion testing of the sutured tendon an early active rehabilitation approach should follow. New splint designs in combination with primary stable tendon suture techniques have the potential to improve the postoperative outcome, presupposing a reliable cooperation of the patient.

Strength of Pulvertaft modifications: tensile testing of porcine flexor tendons

The aim of the study was to present two new modifications of the Pulvertaft weave, allowing a higher number of weaves without the need for a longer overlap. The mechanical properties were measured and compared with the traditional technique. Forty-five pairs of porcine flexor tendons were randomized to a Pulvertaft repair with three weaves, a Double Pulvertaft and Locking Pulvertaft repairs. In the last two repairs one of the tendons in each repair was split in two before weaving. A difference in the maximum stiffness was observed between the three groups (p = 0.024). All repairs failed by the sutures being sheared through the tendons splitting the tendon fibres longitudinally. The two modifications were both stronger than the Pulvertaft weave and provide an alternative when a strong connection is needed and a longer overlap is impossible.

Reach out and grasp the opportunity: reconstructive hand surgery in tetraplegia

Reconstructive upper extremity surgeries in tetraplegia are technically challenging because of the many complicated real-time decisions that need to be made, e.g. extent of release of donor muscle-tendon complex, routing of donor muscles, tissue preparation and optimization, tensioning of muscle-tendon units, balancing joints and suturing tendon-to-tendon attachments. Nerve transfer surgeries can add functionality but also make the reconstruction planning more complex. In this overview, we present some of the fundamental muscle-tendon-joint mechanics studies that allow for single-stage surgical reconstruction of hand function as well as early postoperative activity-based training in patients with cervical spinal cord injuries. We foresee an increased need for studies addressing combined nerve and tendon transfer reconstructions in parallel with patient-perceived outcome investigations. These should be combined with implementation of assistive technology such as functional electrical stimulation for diagnostic, prognostic and training purposes.

Management of Spinal Cord Injury-Induced Upper Extremity Spasticity

Spasticity affects more than 80% of patients with spinal cord injury. Neural mechanisms and musculotendinous alterations lead to typical upper extremity features including shoulder adduction/internal rotation, forearm pronation, and elbow, wrist, and finger flexion. Long-standing spasticity may lead to soft tissue and joint contractures and further impairment of upper extremity function. Surgical management involves tendon lengthening, release, and transfer, as well as selective neurotomy, in an effort to reduce spastic muscle hypertonicity, restore balance, prevent further contracture, and improve posture and function. This article summarizes surgical strategies to improve function of the upper extremity in patients with tetraplegia.

20 years of rheumatoid hand surgery: what did I learn?

Rheumatoid arthritis is one common form of inflammatory arthritis that affects about 1% of the population. Few conditions in hand surgery have undergone such fundamental changes within the last two decades as rheumatoid arthritis has with regard to clinical presentations and treatments. This article provides a personal practice-guided review of the author's decision making and treatment for patients with rheumatoid arthritis in the past two decades.

Minimally Invasive Palmaris Longus Abductorplasty for Severe Carpal Tunnel Syndrome

Camitz abductorplasty is the most commonly used tendon transfer in patients with severe carpal tunnel syndrome with significant muscle wasting and loss of opposition. This procedure requires a long incision in the palm to harvest a strip of palmar aponeurosis to lengthen the palmaris longus tendon, allowing it to reach the abductor pollicis brevis insertion. Several complications have been attributed to this extensive dissection in the palm. We describe a minimally invasive palmaris longus abductorplasty using a strip of free flexor carpi radialis tendon graft to achieve the necessary length. This can be done together with carpal tunnel release in patients with severe carpal tunnel syndrome.

[Secondary tendon reconstruction on the thumb]

Closed tendon ruptures of the thumb that require secondary reconstruction can affect the extensor pollicis longus (EPL), extensor pollicis brevis (EPB) and flexor pollicis longus (FPL) tendons. Treatment of rupture of the EPB tendon consists of refixation to the bone and temporary transfixation of the joint. In the case of preexisting or posttraumatic arthrosis, definitive arthrodesis of the thumb is the best procedure. Closed ruptures of the EPL and FPL tendons at the wrist joint cannot be treated by direct tendon suture. Rupture of the EPL tendon occurs after distal radius fractures either due to protruding screws or following conservative treatment especially in undisplaced fractures. Transfer of the extensor indicis tendon to the distal EPL stump is a good option and free interposition of the palmaris longus tendon is a possible alternative. The tension should be adjusted to slight overcorrection, which can be checked intraoperatively by performing the tenodesis test. Closed FPL ruptures at the wrist typically occur 3-6 months after osteosynthesis of distal radius fractures with palmar plates and are mostly characterized by crepitation and pain lasting for several weeks. They can be prevented by premature plate removal, synovectomy and carpal tunnel release. For treatment of a ruptured FPL tendon in adult patients the options for tendon reconstruction should be weighed up against the less complicated tenodesis or arthrodesis of the thumb interphalangeal joint.

Extensor tendon gap reconstruction: a review

BACKGROUND

The extensor tendons of the hand are located in a superficial position on the dorsal aspect of the hand and are highly susceptible to injury. Laceration, crush and avulsion injuries are common extensor tendon injuries presenting for acute care. Such injuries that involve tendon loss or gaps in the extensor tendons require specialised attention and can be some of the most challenging to repair, as extensor tendons have less excursion than flexor tendons. Reconstructive techniques for such defects may differ according to the location of the defect, especially in Verdan's extensor zones 1-5. Adequate repair of extensor tendon defects in zones 1-5 is especially important because (a) even a 1 mm tendon gap in those zones may cause 20° extension loss, and (b) shortening of the extensor tendon by as little as 1 mm may cause decreased finger flexion.

REVIEW

This article reviews and discusses the literature on the various approaches and techniques for extensor tendon reconstruction, delineated by zone of injury (zones 1-8). CONCLSIONS: Awareness of the various techniques available to repair defects in each zone of injury is important so that surgeons can choose the technique most in alignment with the type of injury, the surgeon's skills, and patient characteristics, and optimise the repair of such injuries.

Tensile mechanical properties of human forearm tendons

Previous studies of the mechanical properties of tendons in the upper limb have used embalmed specimens or sub-optimal methods of measurement. The aim of this study was to determine the biomechanical properties of all tendons from five fresh frozen cadaveric forearms using updated methodology. The cross-sectional area of tendons was accurately measured using a laser reflectance system. Tensile testing was done in a precision servo-hydraulic device with cryo-clamp fixation. We determined that the cross-sectional area of some tendons is variable and directly influences the calculated material properties; visual estimation of this is unreliable. Data trends illustrate that digital extensor tendons possess the greatest tensile strength and a higher Young's modulus than other tendon types.