The influence of protected passive mobilization on the healing of flexor tendons: a biochemical and microangiographic study

Applicability of combined high-frequency and contrast-enhanced ultrasound in finger extensor tendon injuries: three case reports

BACKGROUND

By combining high-frequency and contrast-enhanced ultrasound (CEUS), the position of the severed end of a finger extensor tendon injury and the injury classification can be determined as part of a comprehensive preoperative evaluation in clinical practice. However, there have been no reports of high-frequency ultrasound combined with CEUS for the preoperative diagnosis of human finger extensor tendon injury.

CASES PRESENTATION

One case of complete rupture of the extensor tendon was diagnosed by ultrasound, which was completely consistent with the surgery; one case of incomplete rupture was ultimately confirmed clinically; and one case of distal phalangeal bone base avulsion fracture with tendon contusion and missed diagnosis on the first radiographic examination was confirmed by follow-up radiographic examination.

CONCLUSIONS

Different types of finger extensor tendon injuries exhibit distinctive contrast-enhanced ultrasonography findings. Combined high-frequency and contrast-enhanced ultrasound can accurately locate the position of the severed end of the finger extensor tendon injury before surgery while observing the contrast agent filling area to clarify injury classification, providing a reliable imaging basis for clinical practice and ultimately developing personalized diagnosis and treatment plans for patients to ensure minimal trauma and pain, as well as optimal treatment effects.

Preclinical tendon and ligament models: Beyond the 3Rs (replacement, reduction, and refinement) to 5W1H (why, who, what, where, when, how)

Several tendon and ligament animal models were presented at the 2022 Orthopaedic Research Society Tendon Section Conference held at the University of Pennsylvania, May 5 to 7, 2022. A key objective of the breakout sessions at this meeting was to develop guidelines for the field, including for preclinical tendon and ligament animal models. This review summarizes the perspectives of experts for eight surgical small and large animal models of rotator cuff tear, flexor tendon transection, anterior cruciate ligament tear, and Achilles tendon injury using the framework: "Why, Who, What, Where, When, and How" (5W1H). A notable conclusion is that the perfect tendon model does not exist; there is no single gold standard animal model that represents the totality of tendon and ligament disease. Each model has advantages and disadvantages and should be carefully considered in light of the specific research question. There are also circumstances when an animal model is not the best approach. The wide variety of tendon and ligament pathologies necessitates choices between small and large animal models, different anatomic sites, and a range of factors associated with each model during the planning phase. Attendees agreed on some guiding principles including: providing clear justification for the model selected, providing animal model details at publication, encouraging sharing of protocols and expertise, improving training of research personnel, and considering greater collaboration with veterinarians. A clear path for translating from animal models to clinical practice was also considered as a critical next step for accelerating progress in the tendon and ligament field.

Time-dependent extracellular matrix alterations of young tendons in response to stress relaxation: a model for the Ponseti method

The Ponseti method corrects a clubfoot by manipulation and casting which causes stress relaxation on the tendons. Here, we examined the effect of long-term stress relaxation on tendon extracellular matrix (ECM) by (1) an ex vivo stress relaxation test, (2) an in vitro tenocyte culture with stress relaxation and (3) an in vivo rabbit study. Time-dependent tendon lengthening and ECM alterations including crimp angle reduction and cleaved elastin were observed, which illustrated the mechanism of tissue lengthening behind the treatment-a material-based crimp angle reduction resulted from elastin cleavage. Additionally, in vitro and in vivo results observed restoration of these ECM alterations along with increased elastin level after 7 days of treatment, and the existence of neovascularization and inflammation, indicating the recovery and adaptation from the tendon in reaction to the treatment. Overall, this study provides the scientific background and information that helps explain the Ponseti method.

Preventing postoperative adhesions after hand tendon repair using acellular dermal matrix

AIMS

Postoperative tendon adhesions contribute to functional disability and reconstructive failure. In this study, we present the long-term outcomes of a prospective study in which acellular dermal matrix (ADM) was used to prevent postoperative adhesion after tendon injury.

METHODS

The study was conducted between March 2014 and February 2017. Patients, aged 19-65 years, with an acute single flexor tendon injury in zones 1 or 2, distal to the palmar digital crease were candidates for the study. Patients were allocated to either an ADM treatment group or a control group without ADM treatment.

RESULTS

A total of 37 patients were enrolled in the study: 21 patients in the ADM group and 16 patients in the control group. At six months after surgery, the range of motion in the proximal interphalangeal joint was 81.0±5.1 degrees in the ADM group and 75.8±6.9 degrees in the control group. The range of motion in the distal interphalangeal joint was 79.9±7.1 in the ADM group and 71.2±5.7 degrees in the control group, with significant difference (p=0.03 and p<0.05, respectively). In addition, the total active motion was higher in the ADM group than in the control group. The patients' scores on the Patient Satisfaction Questionnaire were also significantly different, with higher satisfaction scores in the ADM group (p=0.02). The minimal follow-up period was six months.

CONCLUSION

The use of ADM after tendon repair has the potential to significantly improve the outcome of tendon surgery in terms of range of motion.

DECLARATION OF INTEREST

None of the authors has any financial interest in the products, devices, or drugs mentioned in this article.

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.

Flexor tendon rehabilitation in the 21st century: A systematic review

STUDY DESIGN

Systematic review.

INTRODUCTION

The rehabilitation of patients following flexor tendon injury has progressed from immobilization to true active flexion with the addition of wrist motion over the last 75 years.

PURPOSE OF THE STUDY

This review specifically intended to determine whether there is evidence to support one type of exercise regimen, early passive, place and hold, or true active, as superior for producing safe and maximal range of motion following flexor tendon repair.

METHODS

The preferred reporting items for systematic review and meta-analysis (PRISMA-P 2015) checklist was utilized to format the review. Both reviewers collaborated on all aspects of the research, including identifying inclusion/exclusion factors, search terms, reading and scoring articles, and authoring the paper. Articles were independently scored by each reviewer using the Structured Effectiveness Quality Evaluation Scale (SEQES).

RESULTS

A total of nine intervention studies that included a rehabilitative comparison group were systematically reviewed: one pediatric, four comparing passive flexion protocols to place and hold flexion, and four comparing true active flexion to passive and/or place and hold flexion.

DISCUSSION

This review provides moderate to strong evidence that place and hold exercises provide better outcomes than passive flexion protocols for patients with two to six-strand repairs. The studies included in this review suffered from methodological limitations including short timeframes for follow-up, unequal group distribution, and limited attention to repair site strength.

CONCLUSIONS

Based on a lack of superior benefits following true active motion regimens, there is not sufficient evidence to support true active motion as an effective or preferable choice for flexor tendon rehabilitation at this time.

The shift in macrophages polarisation after tendon injury: A systematic review

Background

The role of macrophages (Mφs) in tendon injury healing is controversy. The aims of this study were to determine whether there is a shift in Mφs polarisation after an acute and chronic tendon injury ​and to assess whether the Mφs polarisation between the partial and complete rupture is different.

Methods

This systematic review of the scientific literature was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane guidelines. PubMed database and Excerpta Medica Database (EMBASE) were used for specific search criteria. Only studies measuring Mφs using specific cell markers in Achilles tendon tissue and rotator cuff tendon tissue were included, respectively.

Results

Five Achilles tendon injury studies and four rotator cuff injury studies were included. Expression of the pan Mϕs marker Cluster of Differentiation (CD) 68 was significantly upregulated in acute Achilles tendon ruptures compared to intact tendons, while no significant changes were found in Mφs polarisation markers CD80 (M1 Mφs) and CD206 (M2 Mφs). High levels of CD86 (M1 Mφs) and CD206 were observed in acute partial rupture. Expression of CD68 and CD206 were significantly upregulated in chronic rotator cuff tendinopathy and downregulated as structural failure increases. A low level of CD206 was observed in complete tendon rupture regardless of acute or chronic injury.

Discussion and conclusion

In spite of the limited number of articles included, findings from this study suggested that the process of inflammation plays an important role in acute Achilles tendon injuries, indicated by the increased expression of CD68+ Mφs. Low levels of CD206+ Mφs were constantly observed in complete Achilles tendon rupture, while high levels of CD80+ Mφs and CD206+ Mφs were observed in partial Achilles tendon rupture, which suggested the potential correlation between M2 Mφs and tendon structure. For chronic rotator cuff injury, CD68+ Mφs and CD206+ Mφs were higher in tendinopathic tissues in comparison to the intact control tissues. Both CD68+ Mφs and CD206+ Mφs has an inverse relation to the structural failure in the torn rotator cuff tendon. After tendon rupture, the time point of biopsy specimen collection is an important factor, which could occur in the acute phase or chronic phase. Collectively, the understanding of the roles in Mφs after tendon injury is inadequate, and more research efforts should be devoted to this direction.

The translational potential of this article

This article provided a potential implication on how pan Mφs or M2 Mφs might be associated with ruptured or torn tendon structure. Managing Mφs numbers and phenotypes may lead to possible novel therapeutic approaches to the management of early tendinopathy, early acute tendon rupture, hence, promote healing after restoration surgery.

Splints, with or without wrist immobilization, following surgical repair of flexor tendon lesions of the hand: A systematic review

Splints with or without wrist immobilization can be used during the rehabilitation of flexor tendon lesions of the hand. The evidence base for these techniques has not previously been studied in a systematic review. We sought to thoroughly review patient-reported functional outcomes and pain to compare splinting with or without wrist immobilization. Five bibliographic databases were searched. Studies were considered for inclusion if they were randomized controlled trials or observational comparative studies reporting the difference in outcome among patients treated with or without wrist immobilization. No limits were set on publication date or language. Study selection was performed independently by two authors, and disagreements were resolved by consensus. The review protocol was preregistered in PROSPERO. There were no randomized controlled trials. No studies could be included based on our inclusion criteria. We decided to qualitatively summarize the most relevant studies although they did not meet our inclusion criteria. This resulted in a narrative review of the studies we found relevant. Based on the current literature, it is impossible to provide evidence-based recommendations for or against wrist immobilization during the rehabilitation period following flexor tendon repair. The lack of high-quality evidence points to a need for randomized clinical trials to guide rehabilitation decisions.

A review of cyclic testing protocols for flexor tendon repairs

BACKGROUND

Cyclic testing of flexor tendons aims to simulate post-operative rehabilitation and is more rigorous than static testing. However, there are many different protocols, making comparisons difficult. We reviewed these protocols and suggested two protocols that simulate passive and active mobilization.

METHODS

Literature search was performed to look for cyclic testing protocols used to evaluate flexor tendon repairs. Preload, cyclic load, number of cycles, frequency and displacement rate were categorised.

FINDINGS

Thirty-five studies with 42 different protocols were included. Thirty-one protocols were single-staged, while 11 protocols were multiple-staged. Twenty-nine out of 42 protocols used preload, ranging from 0.2 to 5 N. Preload of 2 N was used in most protocols. The cyclic load that was most commonly used was between 11 and 20 N. Cyclic load with increment of 10 N after each stage was used in multiple-staged protocols. The most commonly used number of cycles was between 100 and 1000. Most protocols used a frequency of <1 Hz and displacement rate between 0 and 20 mm/min.

INTERPRETATION

We propose two single-staged protocols as examples. Protocol 1: cyclic load of 15 N to simulate passive mobilization with preload of 2 N and 2000 cycles at frequency of 0.2 Hz.; Protocol 2: cyclic load of 38 N to simulate active mobilization, with the same preload, number of cycles, and frequency as above. This review consolidates the current understanding of cyclic testing and may help clinicians and investigators improve the design of flexor tendon repairs, allow for comparisons of different repairs using the same protocol, and evaluate flexor tendon repairs more rigorously before clinical applications.

Split Peroneus Longus Free Tendon Autograft Transplantation for the Treatment of Neglected Extensor Hallucis Longus Tendon Laceration: A Case Report

A neglected laceration of the extensor hallucis longus (EHL) tendon is rare. Retraction of the tendon ends often occurs when a laceration is neglected, leading to a substantial tendon deficit. A paucity of case reports is available describing the treatment of EHL laceration with a large area of gap secondary to retraction. Therefore, the treatment recommendations are limited. We present the case of a neglected EHL tendon laceration with a 10.5-cm gap in a healthy 22-year-old female. The EHL tendon laceration was repaired using a split peroneus longus tendon autograft that, to the best of our knowledge, has not been previously reported. At the 3-year follow-up evaluation, the patient retained full function of her hallux and was free of symptoms.

Effect of connective tissue growth factor delivered via porous sutures on the proliferative stage of intrasynovial tendon repair

Recent growth factor, cell, and scaffold-based experimental interventions for intrasynovial flexor tendon repair have demonstrated therapeutic potential in rodent models. However, these approaches have not achieved consistent functional improvements in large animal trials due to deleterious inflammatory reactions to delivery materials and insufficient induction of targeted biological healing responses. In this study, we achieved porous suture-based sustained delivery of connective tissue growth factor (CTGF) into flexor tendons in a clinically relevant canine model. Repairs with CTGF-laden sutures were mechanically competent and did not show any evidence of adhesions or other negative inflammatory reactions based on histology, gene expression, or proteomics analyses at 14 days following repair. CTGF-laden sutures induced local cellular infiltration and a significant biological response immediately adjacent to the suture, including histological signs of angiogenesis and collagen deposition. There were no evident widespread biological effects throughout the tendon substance. There were significant differences in gene expression of the macrophage marker CD163 and anti-apoptotic factor BCL2L1; however, these differences were not corroborated by proteomics analysis. In summary, this study provided encouraging evidence of sustained delivery of biologically active CTGF from porous sutures without signs of a negative inflammatory reaction. With the development of a safe and effective method for generating a positive local biological response, future studies can explore additional methods for enhancing intrasynovial tendon repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2052-2063, 2018.

Tendon injury and repair - A perspective on the basic mechanisms of tendon disease and future clinical therapy

Tendon is an intricately organized connective tissue that efficiently transfers muscle force to the bony skeleton. Its structure, function, and physiology reflect the extreme, repetitive mechanical stresses that tendon tissues bear. These mechanical demands also lie beneath high clinical rates of tendon disorders, and present daunting challenges for clinical treatment of these ailments. This article aims to provide perspective on the most urgent frontiers of tendon research and therapeutic development. We start by broadly introducing essential elements of current understanding about tendon structure, function, physiology, damage, and repair. We then introduce and describe a novel paradigm explaining tendon disease progression from initial accumulation of damage in the tendon core to eventual vascular recruitment from the surrounding synovial tissues. We conclude with a perspective on the important role that biomaterials will play in translating research discoveries to the patient.

STATEMENT OF SIGNIFICANCE

Tendon and ligament problems represent the most frequent musculoskeletal complaints for which patients seek medical attention. Current therapeutic options for addressing tendon disorders are often ineffective, and the need for improved understanding of tendon physiology is urgent. This perspective article summarizes essential elements of our current knowledge on tendon structure, function, physiology, damage, and repair. It also describes a novel framework to understand tendon physiology and pathophysiology that may be useful in pushing the field forward.

A Biomechanical Analysis of the Interlock Suture and a Modified Kessler-Loop Lock Flexor Tendon Suture

OBJECTIVE

In this work, we attempted to develop a modified single-knot Kessler-loop lock suture technique and compare the biomechanical properties associated with this single-knot suture technique with those associated with the conventional modified Kessler and interlock suture techniques.

METHODS

In this experiment, a total of 18 porcine flexor digitorum profundus tendons were harvested and randomly divided into three groups. The tendons were transected and then repaired using three different techniques, including modified Kessler suture with peritendinous suture, interlock suture with peritendinous suture, and modified Kessler-loop lock suture with peritendinous suture. Times required for suturing were recorded and compared among groups. The groups were also compared with respect to 2-mm gap load, ultimate failure load, and gap at failure.

RESULTS

For tendon repair, compared with the conventional modified Kessler suture technique, the interlock and modified Kessler-loop lock suture techniques resulted in significantly improved biomechanical properties. However, there were no significant differences between the interlock and modified Kessler-loop lock techniques with respect to biomechanical properties, gap at failure, and time required.

CONCLUSIONS

The interlock and modified Kessler-loop lock techniques for flexor tendon sutures produce similar mechanical characteristics in vitro.

Perfusion of the Rotator Cuff Tendon According to the Repair Configuration Using an Indocyanine Green Fluorescence Arthroscope: A Preliminary Report

BACKGROUND

The disturbance of rotator cuff tendon perfusion has been connected with the suture-bridge configuration repair (SBCR) technique; however, in vivo assessments of the tendon blood supply have been problematic with other modalities. An evaluation of tissue perfusion by an indocyanine green (ICG) fluorescence arthroscope has been developed to counteract this difficulty.

PURPOSE

To verify the hindrance of perfusion in SBCR, we used an ICG fluorescence camera to compare parallel-type transosseous repair (PTR) and SBCR in rabbits immediately and at 3 days after rotator cuff repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

Acute rotator cuff repair was performed on the shoulders of 10 rabbits. Both shoulders were repaired using either PTR or SBCR. For PTR, simple repair was performed through 2 parallel transosseous tunnels created using a microdrill. For SBCR, 2 additional crisscross transosseous tunnels were added to mimic arthroscopic SBCR. Immediately after repair, ICG was injected through the ear vein, and images were recorded using an ICG fluorescence camera. Tendon perfusion was compared by measuring fluorescence intensity using ImageJ software in both methods. At 3 days after rotator cuff repair, a reassessment of ICG fluorescence was performed. In addition, as a subsidiary study, a comparison of each repair method and a healthy tendon was performed (PTR vs healthy tendon and SBCR vs healthy tendon). Six rabbits (3 for each comparison) were included.

RESULTS

Immediately after rotator cuff repair, the mean (±SD) grayscale intensity of ICG fluorescence was weaker in SBCR than PTR in 10 specimens (65.9 ± 47.6 vs 84.3 ± 53.4 per pixel, respectively; P = .003). At 3 days after repair, 8 specimens were included in the analysis because suture strands failed in 2 specimens in SBCR. The mean intensity of fluorescence was still weaker in SBCR compared with PTR (52.5 ± 13.7 vs 60.2 ± 22.7 per pixel, respectively; P = .077). The mean fluorescence intensity compared with a healthy tendon was 83.2% ± 9.5% in PTR and 63.2% ± 13.2% in SBCR.

CONCLUSION

Our ICG fluorescence camera system was able to detect ICG fluorescence in an acute rabbit rotator cuff repair model. SBCR showed inferior tendon perfusion immediately after repair. At 3 days after repair, SBCR still showed inferior fluorescence intensity, although it did not reach statistical significance.

CLINICAL RELEVANCE

In this study, SBCR hindered perfusion at the tendon in the compressed area. This finding may affect rotator cuff tendon healing and failure mode.

Effects of boric acid on the healing of Achilles tendons of rats

PURPOSE

Tendinous lesions are among the most frequent pathologies encountered in sportsmen. The objectives of new treatments are to improve the healing process and reduce the recovery time. Boron plays an important role in the wound repair process by increasing components of extracellular matrix and angiogenesis. This animal study aimed to investigate the effect of boric acid on healing of the Achilles tendon.

METHODS

The right Achilles tendons of 40 rats were completely sectioned, and the rats were randomly divided into five groups. Each group consisted of eight rats. Groups 1 and 2 were oral boric acid groups with the doses of 4 and 8 mg/kg/day boric acid, respectively. Group 3 was the local boric acid group (8 mg/kg boric acid intratendinous injection). Group 4 was administered both oral and local boric acid (8 mg/kg/day orally and 8 mg/kg boric acid intratendinous injection), and group 5 was the control group with no boric acid application. At the end of the fourth week, all the rats were killed and histopathological examination of the Achilles tendon repair site was made.

RESULTS

Histopathological examination of the tissue sections revealed more properly oriented collagen fibres, more normal cellular distribution of tenocytes and more properly organized vascular bundles in group 1 and group 2, which were the groups administered oral boric acid. Pathological sum scores of groups 1 and 2 were less than those of the other groups, and the differences between the oral boric acid groups (group 1 and group 2) and the other three groups (groups 3, 4 and 5) were statistically significant (p = 0.001).

CONCLUSION

As boric acid is safe and toxicity even after very high doses is unusual, oral boric acid may be used as an agent to improve the healing process of tendon injuries. However, biomechanical tests should also be performed to show the effect of boric acid on strength and endurance of the tendon before it can be used in clinical practice.

Reinforcement of the Flexor Tendon Repair Using Human Amniotic MembraneA Biomechanical Evaluation Using the Modified Kessler Method of Tendon Repair

BACKGROUND

Human amniotic membrane is used to prevent peritendinous adhesions after tendon injuries. This study compares the mechanical properties of modified Kessler repairs and modified Kessler repairs strengthened using multiple layers of human amniotic membrane.

METHODS

Twenty flexor digitorum profundus tendons of sheep forelimbs were sutured by the two-strand modified Kessler technique (group A) and by the two-strand modified Kessler repair reinforced with multiple layers of human amniotic membrane (group B). To assess the mechanical performance of the repairs, tendons were subjected to a linear noncyclic load-to-failure test using a material testing machine. Outcome measures included ultimate forces and the mode of failure.

RESULTS

The mean ± SD value of the failure strength was 34.6 ± 1.64 N for group A and 50.6 ± 5.60 N for group B. The reinforced repair provided a significantly higher ultimate load compared with the nonreinforced group (P < .001). All of the specimens failed due to suture breakage at the repair site.

CONCLUSIONS

The results of this study show that the modified Kessler repair can be reinforced effectively with human amniotic membrane.

Cell and Biologic-Based Treatment of Flexor Tendon Injuries

The two primary factors leading to poor clinical results after intrasynovial tendon repair are adhesion formation within the digital sheath and repair-site elongation and rupture. As the outcomes following modern tendon multi-strand repair and controlled rehabilitation techniques are often unsatisfactory, alternative approaches, such as the application of growth factors and mesenchymal stem cells (MSCs), have become increasingly attractive treatment options. Successful biological therapies require carefully controlled spatiotemporal delivery of cells, growth factors, and biocompatible scaffold matrices in order to simultaneously (1) promote matrix synthesis at the tendon repair site leading to increased biomechanical strength and stiffness and (2) suppress matrix synthesis along the tendon surface and synovial sheath preventing adhesion formation. This review summarizes recent cell and biologic-based experimental treatments for flexor tendon injury, with an emphasis on large animal translational studies.

Effect of adipose-derived stromal cells and BMP12 on intrasynovial tendon repair: A biomechanical, biochemical, and proteomics study

The outcomes of flexor tendon repair are highly variable. As recent efforts to improve healing have demonstrated promise for growth factor- and cell-based therapies, the objective of the current study was to enhance repair via application of autologous adipose derived stromal cells (ASCs) and the tenogenic growth factor bone morphogenetic protein (BMP) 12. Controlled delivery of cells and growth factor was achieved in a clinically relevant canine model using a nanofiber/fibrin-based scaffold. Control groups consisted of repair-only (no scaffold) and acellular scaffold. Repairs were evaluated after 28 days of healing using biomechanical, biochemical, and proteomics analyses. Range of motion was reduced in the groups that received scaffolds compared to normal. There was no effect of ASC + BMP12 treatment for range of motion or tensile properties outcomes versus repair-only. Biochemical assays demonstrated increased DNA, glycosaminoglycans, and crosslink concentration in all repair groups compared to normal, but no effect of ASC + BMP12. Total collagen was significantly decreased in the acellular scaffold group compared to normal and significantly increased in the ASC + BMP12 group compared to the acellular scaffold group. Proteomics analysis comparing healing tendons to uninjured tendons revealed significant increases in proteins associated with inflammation, stress response, and matrix degradation. Treatment with ASC + BMP12 amplified these unfavorable changes. In summary, the treatment approach used in this study induced a negative inflammatory reaction at the repair site leading to poor healing. Future approaches should consider cell and growth factor delivery methods that do not incite negative local reactions.

Healing disturbance with suture bridge configuration repair in rabbit rotator cuff tear

BACKGROUND

Medial row failure has been reported in the suture bridge technique of rotator cuff repair. This study compared the healing response of suture bridge configuration repair (SBCR) and parallel type transosseous repair (PTR).

METHODS

Acute rotator cuff repair was performed in 32 rabbits. Both shoulders were repaired using PTR or SBCR. In PTR, simple PTR was performed through 2 parallel transosseous tunnels created using a microdrill. In SBCR, 2 additional crisscross transosseous tunnels were added to mimic arthroscopic SBCR. At 1, 2, and 5 weeks postoperatively, comparative biomechanical testing was performed in 8 rabbits, and histologic analysis, including immunohistochemical staining for CD31, was performed in 4 rabbits.

RESULTS

Failure loads at 1 week (38.12 ± 20.43 N vs 52.00 ± 27.23 N; P = .284) and 5 weeks (97.93 ± 48.35 N vs 119.60 ± 60.81 N; P = .218) were not statistically different between the SBCR and PTR groups, respectively, but were significantly lower in the SBCR group than in the PTR group (23.56 ± 13.56 N vs. 44.25 ± 12.53 N; P = .009), respectively, at 2 weeks. Markedly greater fibrinoid deposition was observed in the SBCR group than in the PTR group at 2 weeks. For vascularization, there was a tendency that more vessels could be observed in PTR than in SBCR at 2 weeks (15.9 vs 5.6, P = .068).

CONCLUSIONS

In a rabbit acute rotator cuff repair model, SBCR exhibited inferior mechanical strength, and fewer blood vessels were observed at the healing site at 2 weeks postoperatively. Medial row tendon failure was more common in SBCR. Surgeons should consider the clinical effect of SBCR when performing rotator cuff repair.

Flexor Tendon Repair With Looped Suture: 1 Versus 2 Knots

PURPOSE

To assess the strength of flexor tendon repair with looped suture. We hypothesized that, after passing the intact looped suture in the desired repair configuration, splitting the loop and tying 2 independent knots would increase the strength of flexor tendon repair.

METHODS

Thirty-two flexor tendons were harvested and were sharply transected in zone II. The tendons were repaired with a 4-strand core suture repair using 3-0 looped nonabsorbable nylon suture. The harvested tendons were randomly assigned and repaired with either a 1- or a 2-knot construct. The repaired flexor tendons were fixed in a servohydraulic material testing system and were loaded to failure either with uniaxial tension or cyclically.

RESULTS

The average force at failure was 43 N for the 1-knot repair and 28 N for the 2-knot repair. The mode of failure of 15 of the flexor tendon repairs that were cyclically loaded to failure was suture pull-out. The average number of cycles and force in cyclic testing that caused failure of flexor tendon repairs was 134 cycles and 31 N for tendons repaired with looped 3-0 suture tied with 1 knot and 94 cycles and 33 N for tendons repaired with looped 3-0 suture tied with 2 knots.

CONCLUSIONS

Our hypothesis was disproved by the results of this study.

CLINICAL RELEVANCE

This study suggests that, when using looped suture, tying 2 independent knots instead of tying a single knot does not increase the strength of the flexor tendon repair.

Case Study: Osteosynthesis, Tenodesis Effect, and Side-to-Side Tendon Repair in Hand Transplantation

Osteosynthesis and tendon repair are essential in upper extremity transplantation to optimally restore function. Transplant surgeons should be aware of all technical issues involved in osteosynthesis, tendon balancing, and tension setting as well as repair in an effort to optimize the function of the transplanted hand. Preoperative planning is vital to achieve good functional results. We present a case of successful osteosynthesis and side-to-side tendon repair, which led to a desirable functional outcome in hand transplantation.

Influence of different length of core suture purchase among suture row on the strength of 6-strand tendon repairs

In multi-strand suture methods consisting of several suture rows, the different length of core suture purchase between each suture row may affect the strength of repairs. We evaluated the influence of the different length of core suture purchase between each suture row on the strength of 6-strand tendon repairs. Rabbit flexor tendons were repaired by using a triple-looped suture technique in which the suture purchase length in each suture row was modified. Group 1, all lengths are 8-mm. Group 2, all lengths are 10-mm. Group 3, two are 10-mm and one is 8-mm. Group 4, one is 10-mm and two are 8-mm. The repaired tendons were subjected to load-to-failure test. The gap strength was significantly greater in Group 1 and Group 2 than in Group 3 and Group 4. This study demonstrates that maintaining equal core suture purchase lengths of each suture row increases the gap resistance.

The early inflammatory response after flexor tendon healing: a gene expression and histological analysis

Despite advances in surgical techniques over the past three decades, tendon repairs remain prone to poor clinical outcomes. Previous attempts to improve tendon healing have focused on the later stages of healing (i.e., proliferation and matrix synthesis). The early inflammatory phase of tendon healing, however, is not fully understood and its modulation during healing has not yet been studied. Therefore, the purpose of this work was to characterize the early inflammatory phase of flexor tendon healing with the goal of identifying inflammation-related targets for future treatments. Canine flexor tendons were transected and repaired using techniques identical to those used clinically. The inflammatory response was monitored for 9 days. Temporal changes in immune cell populations and gene expression of inflammation-, matrix degradation-, and extracellular matrix-related factors were examined. Gene expression patterns paralleled changes in repair-site cell populations. Of the observed changes, the most dramatic effect was a greater than 4,000-fold up-regulation in the expression of the pro-inflammatory factor IL-1β. While an inflammatory response is likely necessary for healing to occur, high levels of pro-inflammatory cytokines may result in collateral tissue damage and impaired tendon healing. These findings suggest that future tendon treatment approaches consider modulation of the inflammatory phase of healing.

The effects of chronic unloading and gap formation on tendon-to-bone healing in a rat model of massive rotator cuff tears

The objective of this study was to understand the effect of pre-repair rotator cuff chronicity on post-repair healing outcomes using a chronic and acute multi-tendon rat rotator cuff injury model. Full-thickness dual tendon injuries (supra- and infraspinatus) were created unilaterally in adult male Sprague Dawley rats, and left chronically detached for 8 or 16 weeks. After chronic detachment, tears were repaired and acute dual tendon injuries were created and immediately repaired on contralateral shoulders. Tissue level outcomes for bone, tendon, and muscle were assessed 4 or 8 weeks after repair using histology, microcomputed tomography, biomechanical testing, and biochemical assays. Substantial gap formation was seen in 35% of acute repairs and 44% of chronic repairs. Gap formation negatively correlated with mechanical and structural outcomes for both healing time points regardless of injury duration. Bone and histomorphometry, as well as biomechanics, were similar between acute and chronic injury and repair regardless of chronicity and duration of healing. This study was the first to implement a multi-tendon rotator cuff injury with surgical repair following both chronic and acute injuries. Massive tear in a rodent model resulted in gap formation regardless of injury duration which had detrimental effects on repair outcomes.

Development of biodegradable polycaprolactone film as an internal fixation material to enhance tendon repair: an in vitro study

Background

Current tendon repair techniques do not provide sufficient tensile strength at the repair site, and thus early active motion rehabilitation after tendon repair is discouraged. To enhance the post-operative tensile strength, we proposed and tested an internal fixation technique using a polycaprolactone (PCL) biofilm. PCL was chosen for its good biocompatibility, excellent mechanical strength, and an appropriate degradation time scale.

Methods

PCL biofilms were prepared by a modified melt-molding/leaching technique, and the physical and mechanical properties and in vitro degradation rate were assessed. The pore size distribution of the biofilm and the paratenon of native tendons were observed using scanning electron microscopy. Next, we determined whether this biofilm could enhance the tensile strength of repaired tendons. We performed tensile tests on rabbit Achilles tendons that were first lacerated and then repaired: 1) using modified Kessler suture combined with running peripheral suture (‘control’ group), or 2) using biofilm to wrap the tendon and then fixation with sutures (‘biofilm’ group). The influence of different repair techniques on tendon tensile strength was evaluated by mechanical testing.

Results

The novel biofilm had supple texture and a smooth surface. The mean thickness of the biofilm was 0.25 mm. The mean porosity of the biofilm was 45.3%. The paratenon of the rabbit Achilles tendon had pores with diameters ranging from 1 to 9 μm, which were similar to the 4–12 μm diameter pores in the biofilm cross-section. The weight loss of the biofilms at 4 weeks was only 0.07%. The molecular weight of PCL biofilms did not change after immersion in phosphate buffered saline for 4 weeks. The failure loads of the biofilm were similar before (48 ± 9 N) and after immersion (47 ± 7 N, P > 0.1). The biofilm group had ~70% higher mean failure loads and 93% higher stiffness compared with the control group.

Conclusions

We proposed and tested an internal fixation technique using a PCL biofilm to enhance tendon repair. Internal fixation with the biofilm followed by standard suturing can significantly increase the tensile strength of tendon repair sites. This technique has the potential to allow active motion rehabilitation during the early post-operative period.

Controlled delivery of mesenchymal stem cells and growth factors using a nanofiber scaffold for tendon repair

Outcomes after tendon repair are often unsatisfactory, despite improvements in surgical techniques and rehabilitation methods. Recent studies aimed at enhancing repair have targeted the paucicellular nature of tendon for enhancing repair; however, most approaches for delivering growth factors and cells have not been designed for dense connective tissues such as tendon. Therefore, we developed a scaffold capable of delivering growth factors and cells in a surgically manageable form for tendon repair. Platelet-derived growth factor BB (PDGF-BB), along with adipose-derived mesenchymal stem cells (ASCs), were incorporated into a heparin/fibrin-based delivery system (HBDS). This hydrogel was then layered with an electrospun nanofiber poly(lactic-co-glycolic acid) (PLGA) backbone. The HBDS allowed for the concurrent delivery of PDGF-BB and ASCs in a controlled manner, while the PLGA backbone provided structural integrity for surgical handling and tendon implantation. In vitro studies verified that the cells remained viable, and that sustained growth factor release was achieved. In vivo studies in a large animal tendon model verified that the approach was clinically relevant, and that the cells remained viable in the tendon repair environment. Only a mild immunoresponse was seen at dissection, histologically, and at the mRNA level; fluorescently labeled ASCs and the scaffold were found at the repair site 9days post-operatively; and increased total DNA was observed in ASC-treated tendons. The novel layered scaffold has the potential for improving tendon healing due to its ability to deliver both cells and growth factors simultaneously in a surgically convenient manner.

An experimental study comparing active mobilization to passive flexion-active extension-active flexion after flexor tendon repair in zone 2

PURPOSE

Both passive flexion-active extension and active rehabilitation have shown advantages and disadvantages in tendon healing. The purpose of this study was to measure the effect of a combination of these 2 rehabilitation protocols.

METHODS

A tendon injury model was used in white Leghorn chickens. Thirty-two animals were randomly assigned into 4 groups. We compared an unrestricted active flexion rehabilitation (UA) group with 3 groups starting passive flexion, active extension, and active flexion (PAA) at 5, 9.5 and 14 days after repair. The tensile properties and range of motion of the 3 interphalangeal joints were evaluated for 3 postoperative weeks.

RESULTS

In terms of tensile properties of the operated foot, PAA-14 was higher than any other group, and PAA-5 was the lowest. There was no significant difference between the PAA-9.5 and UA. For the range of motion, there were significant differences between all 4 groups: UA increased the most, PAA-14 increased the least, and PAA-5 increased more than PAA-9.5. For the rupture rate, UA and PAA-5 were higher than were PAA-9.5 and PAA-14.

CONCLUSIONS

The results indicate that the PAA-9.5 and UA may give the best balance (tensile properties, range of motion, rupture rates) of these rehabilitation protocols. PPA-9.5 and UA had similar moderate tensile properties. When considering an increased range of motion, the UA method may be the most appropriate despite its higher rupture rate. When considering a lower rupture rate, PAA-9.5 may be the most suitable.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Surgical reconstruction and mobilization therapy for a retracted extensor hallucis longus laceration and tendon defect repaired by split extensor hallucis longus tendon lengthening and dermal scaffold augmentation

A reconstructive technique and physical therapy protocol is presented for the treatment of extensor hallucis longus (EHL) lacerations with critical size defects caused by tendon retraction. The primary goal of treatment was to restore EHL structure and function without the use of a bridging allograft or tendon transfer. The technique is performed by split lengthening the distal segment of the lacerated EHL and rotating the lengthened segment proximally 180° to bridge the tendon defect. The lengthened tendon is then sutured to the proximal segment of the EHL. The EHL is then tubularized with an acellular dermal scaffold at the region of tendon rotation to improve tendon strength, minimize the probability of tendon overlengthening or re-rupture, and improve the tendon gliding motion, which can be compromised by the tendon irregularity caused by rotation of the tendon. Postoperative range of motion therapy should be initiated at 3 weeks postoperatively. A case report of this technique and postoperative mobilization protocol is presented. The American Orthopaedic Foot and Ankle Society midfoot score at 3 and 6 months postoperatively was 90 of 100. The patient regained active dorsiflexion motion of the hallux without functional limitations, deformity, or contracture of the hallux. The advantages of this technique include that a large cadaveric allograft is not needed to bridge a critical size tendon defect and tendon lengthening provides a biologically active tendon graft without the secondary comorbidities and dysfunction commonly associated with tendon transfer procedures.

The role of mechanobiology in tendon healing

Mechanical cues affect tendon healing, homeostasis, and development in a variety of settings. Alterations in the mechanical environment are known to result in changes in the expression of extracellular matrix proteins, growth factors, transcription factors, and cytokines that can alter tendon structure and cell viability. Loss of muscle force in utero or in the immediate postnatal period delays tendon and enthesis development. The response of healing tendons to mechanical load varies depending on anatomic location. Flexor tendons require motion to prevent adhesion formation, yet excessive force results in gap formation and subsequent weakening of the repair. Excessive motion in the setting of anterior cruciate ligament reconstruction causes accumulation of macrophages, which are detrimental to tendon graft healing. Complete removal of load is detrimental to rotator cuff healing; yet, large forces are also harmful. Controlled loading can enhance healing in most settings; however, a fine balance must be reached between loads that are too low (leading to a catabolic state) and too high (leading to microdamage). This review will summarize existing knowledge of the mechanobiology of tendon development, homeostasis, and healing.

BIOMECHANICS AND HISTOLOGICAL ANALYSIS IN RABBIT FLEXOR TENDONS REPAIRED USING THREE SUTURE TECHNIQUES (FOUR AND SIX STRANDS) WITH EARLY ACTIVE MOBILIZATION

Objective: Analyzing suture time, biomechanics (deformity between the stumps) and the histology of three groups of tendinous surgical repair: Brazil-2 (4-strands) which the end knot (core) is located outside the tendon, Indiana (4-strands) and Tsai (6-strands) with sutures technique which the end knot (core) is inner of the tendon, associated with early active mobilization. Methods: The right calcaneal tendons (plantar flexor of the hind paw) of 36 rabbits of the New Zealand breed (Oryctolagus cuniculus) were used in the analysis. This sample presents similar size to human flexor tendon that has approximately 4.5 mm (varying from 2mm). The selected sample showed the same mass (2.5 to 3kg) and were male or female adults (from 8 ½ months). For the flexor tendons of the hind paws, sterile and driven techniques were used in accordance to the Committee on Animal Research and Ethics (CETEA) of the University of the State of Santa Catarina (UDESC), municipality of Lages, in Brazil (protocol # 1.33.09). Results: In the biomechanical analysis (deformity) carried out between tendinous stumps, there was no statistically significant difference (p>0.01). There was no statistical difference in relation to surgical time in all three suture techniques with a mean of 6.0 minutes for Tsai (6- strands), 5.7 minutes for Indiana (4-strands) and 5.6 minutes for Brazil (4-strands) (p>0.01). With the early active mobility, there was qualitative and quantitative evidence of thickening of collagen in 38.9% on the 15^th day and in 66.7% on the 30^th day, making the biological tissue stronger and more resistant (p=0.095). Conclusion: This study demonstrated that there was no histological difference between the results achieved with an inside or outside end knot with respect to the repaired tendon and the number of strands did not affect healing, vascularization or sliding of the tendon in the osteofibrous tunnel, which are associated with early active mobility, with the repair techniques applied.

Outcome of zone 2 flexor tendon injuries: Kleinert versus controlled active motion therapy regimens

Introduction

No single optimal regimen for the rehabilitation of flexor tendon injuries has yet been determined. We aimed to evaluate if a change in rehabilitation from a modified Kleinert to a controlled active motion (CAM) regimen had an effect on outcomes in a regional plastic surgery unit. We did this by comparing ruptures and range of movement of zone 2 repairs following both Kleinert and CAM regimens.

Methods

We performed a retrospective case series review, analysing data collected prospectively between 2004 and 2007. During 2004 and 2005, patients were rehabilitated with a modified Kleinert regimen, and during 2006 and 2007 a CAM regimen was used. We looked at total active motion (TAM) and ruptures at 12-week follow-up for all zone 2 repairs, and compared the two regimens.

Results

There were 38 patients with 42 injured digits in the Kleinert group, and 34 patients with 39 injured digits in the CAM group. There was no statistically significant difference in TAM achieved between the Kleinert and CAM regimens overall (70% versus 72% of normal in each group respectively, P = 0.70 t-test). Patients over 30 years old achieved significantly worse outcomes in the Kleinert group than in the CAM group ( P = 0.03). One digit ruptured following a Kleinert regimen (2.6%) compared with four digits in the CAM group (11.7%).

Conclusion

In this study, we found no overall difference in outcome following a Kleinert or CAM rehabilitation regimen. Rupture rates were higher in the CAM group by four-fold. In our patients those over 30 years had poorer outcomes when rehabilitated with a Kleinert regimen.

The longer pull-out suture as a transmission suture for early active motion of repaired flexor tendon at the proximal zone-2

OBJECTIVES

The purpose of the current study was to clinically evaluate the technique of longer pull-out suture as a transmission suture for early active motion after flexor tendon repair in the proximal zone-2.

METHOD

Eleven patients (eight adult male, two adult female and one child) with 19 proximal zone II flexor tendon lacerations were included. Mean age was 35 years. The patients were encouraged to perform active mobilization of the injured digits by themselves with full range of flexion from the first postoperative day. The pull-out suture was removed at the 8-10 weeks after the operation.

RESULTS

The mean follow-up was 39 months. The procedure was well tolerated by all of the patients. A patient of whom pull-out suture was traumatized and loosened at 6th week showed fair result. Two other patients with a history of blunt trauma were also found to have fair results. Overall 16 of the 19 digits were evaluated as excellent or good by the Strickland criteria.

CONCLUSION

The results of this method show that the longer pull-out suture technique as a transmission suture followed by early active mobilization is safe, has a low re-rupture rate and is easy to perform for proximal zone-2 flexor tendon injuries.

The effectiveness of continuous passive motion on range of motion, pain and muscle strength following rotator cuff repair: a systematic review

Objective: To systematically review the evidence on the effect of continuous passive motion, combined with usual physiotherapy management, on increasing shoulder joint range of motion and muscle strength, and reducing shoulder pain in adults following rotator cuff repair, compared with standard physiotherapy.

Data sources: A comprehensive search in available bibliographic electronic databases was undertaken to locate eligible studies. Reference tracing was also used to locate studies.

Review methods: Randomized controlled trials reporting on the effect of continuous passive motion on increasing shoulder joint range of motion and muscle strength and reducing shoulder pain in adults following rotator cuff repair were included in the review. The PEDro scale was used to determine the methodological quality of the studies. Data were summarized in a narrative form because of their heterogeneity.

Results: Four randomized controlled trials were eligible for this review. One Japanese article was excluded as the text was unavailable in English. The methodological quality of the included studies averaged 7.67. Continuous passive motion was found to improve shoulder range of motion in two studies. One study found a decrease in pain in the intervention group and one study found that continuous passive motion improves muscle strength.

Conclusion: Continuous passive motion is safe to use with physiotherapy treatment following rotator cuff repair surgery. It may help to prevent secondary complications post operatively.

Optimally strong tendon repair using braided polyethylene strand: 2-strand heavy-gauge locking technique vs. multiple-strand technique

BACKGROUND

We conducted an in vitro study to investigate the strongest tensile force for tendon repair using a braided polyblend suture strand material, employing a 2-strand heavy-gauge side-locking loop technique, comparing it with other multiple-strand repair techniques.

METHODS

Using the United States Pharmacopeial Convention (USP) 2 and 5-sized braided polyblend strands, 3 repair techniques were evaluated after suturing transacted bovine gastrocnemius tendons: 2-strand side-locking loop, 4-strand Savage, and 6-strand Yoshizu-1 techniques. Ultimate tensile force and mode of failure at strand rupture were examined (n=5 for each combination).

FINDINGS

The ultimate tensile forces was observed with USP2-side-locking loop (mean 402 N), USP5-side-locking loop (mean 748 N), USP2-Savage (mean 552 N), and USP2-Yoshizu-1 Groups (mean 598 N). The USP5-side-locking loop Group had proportionally greater ultimate tensile force than the USP2-side-locking loop Group. However, with the number of strands doubled or tripled, resulting strengths were only 1.4 times or 1.5 times greater. The mode of failure was rupture at the locking loop portion in all side-locking loop Group samples, pull-through of the strand from the tendon in all Savage Group samples, and either pull-through of the strand from the tendon (40%) or rupture at the knot (60%) in the Yoshizu-1 Group samples.

INTERPRETATION

Greater numbers of strands do not achieve proportionally greater strong tensile force in the repaired tendon. When employing the side-locking loop technique for secured locking formation, the heavier strand yields markedly greater tensile force even with only 2 strands, and thus greater holding ability.

Mechanical strength of the side-to-side versus Pulvertaft weave tendon repair

PURPOSE

The side-to-side (SS) tendon suture technique was designed to function as a repair that permits immediate postoperative activation and mobilization of a transferred muscle. This study was designed to test the strength and stiffness of the SS technique against a variation of the Pulvertaft (PT) repair technique.

METHODS

Flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons were harvested from 4 fresh cadavers and used as a model system. Seven SS and 6 PT repairs were performed, using the FDS as the donor and the FDP as the recipient tendon. For SS repairs, the FDS was woven through one incision in the FDP and was joined with 4 cross-stitch running sutures down both sides and one double-loop suture at each tendon free end. For PT repairs, the FDS was woven through 3 incisions in the FDP and joined with a double-loop suture at both ends of the overlap and 4 evenly spaced mattress sutures between the ends. Tendon repairs were placed in a tensile testing machine, preconditioned, and tested to failure.

RESULTS

There were no statistically significant differences in cross-sectional area (p = .99) or initial length (p = .93) between SS and PT repairs. Therefore, all comparisons between methods were made using measures of loads and deformations, rather than stresses and strains. All failures occurred in the repair region, rather than at the clamps. However, failure mechanisms were different between the 2 techniques-PT repairs failed by the suture knots either slipping or pulling through the tendon material, followed by the FDS tendon pulling through the FDP tendon; SS repairs failed by shearing of fibers within the FDS. Load at first failure, ultimate load, and repair stiffness were all significantly different between SS and PT techniques; in all cases, the mean value for SS was higher than for PT.

CONCLUSIONS

The SS repair using a cross-stitch suture technique was significantly stronger and stiffer than the PT repair using a mattress suture technique. This suggests that using SS repairs could enable patients to load the repair soon after surgery. Ultimately, this should reduce the risk of developing adhesions and result in improved functional outcome and fewer complications in the acute postoperative period. Future work will address the specific mechanisms (eg, suture-throw technique and tendon-weave technique) that underlie the improved strength and stiffness of the SS repair.

The effect of postoperative passive motion on rotator cuff healing in a rat model

BACKGROUND

Surgical repairs of torn rotator cuff tendons frequently fail. Immobilization has been shown to improve tissue mechanical properties in an animal model of rotator cuff repair, and passive motion has been shown to improve joint mechanics in animal models of flexor tendon repair. Our objective was to determine if daily passive motion would improve joint mechanics in comparison with continuous immobilization in a rat rotator cuff repair model. We hypothesized that daily passive motion would result in improved passive shoulder joint mechanics in comparison with continuous immobilization initially and that there would be no differences in passive joint mechanics or insertion site mechanical properties after four weeks of remobilization.

METHODS

A supraspinatus injury was created and was surgically repaired in sixty-five Sprague-Dawley rats. Rats were separated into three postoperative groups (continuous immobilization, passive motion protocol 1, and passive motion protocol 2) for two weeks before all underwent a remobilization protocol for four weeks. Serial measurements of passive shoulder mechanics (internal and external range of motion and joint stiffness) were made before surgery and at two and six weeks after surgery. After the animals were killed, collagen organization and mechanical properties of the tendon-to-bone insertion site were determined.

RESULTS

Total range of motion for both passive motion groups (49% and 45% of the pre-injury values) was less than that for the continuous immobilization group (59% of the pre-injury value) at two weeks and remained significantly less following four weeks of remobilization exercise. Joint stiffness at two weeks was increased for both passive motion groups in comparison with the continuous immobilization group. At both two and six weeks after repair, internal range of motion was significantly decreased whereas external range of motion was not. There were no differences between the groups in terms of collagen organization or mechanical properties.

CONCLUSIONS

In this model, immediate postoperative passive motion was found to be detrimental to passive shoulder mechanics. We speculate that passive motion results in increased scar formation in the subacromial space, thereby resulting in decreased range of motion and increased joint stiffness. Passive motion had no effect on collagen organization or tendon mechanical properties measured six weeks after surgery.

[Combined flexor tendon and nerve injury of the hand]

Any restoration of hand function following tendon and nerve injury has to include the repair or replacement of the hand's ability to perform a great many tasks. It is hard at first to appreciate fully the loss that occurs with flexor tendon injury. Also sensibility can be compromised from tendon injury without direct injury to the nerve, as object recognition in the absence of vision requires finger movement. When peripheral nerve injury is combined with flexor tendon injury, sensibility is directly impaired. There is a loss in the sense of finger or thumb position, pain temperature and touch or pressure recognition, in addition to the tendon injury. However, the outcome after operative treatment of these"minor" injuries of the hand is horrible. Therefore, we try to summarize practical consequences for the repair of combined flexor tendon and nerve injuries which will improve operative outcome. These guidelines are based on current scientific knowledge and our own experience.

Evaluation of a new 4-strand flexor tendon repair in a cadaveric porcine model

PURPOSE

Numerous flexor tendon repairs have been described. The ideal core flexor tendon repair optimizes strength characteristics while minimizing factors felt to contribute to adhesion formation. The present study compares ultimate tensile strength, gap strength, and surgical time in the Lahey repair, a new 4-strand flexor tendon repair, to 2 previously described techniques.

METHODS

The flexor digitorum profundus tendons of 30 porcine forelimbs were repaired in situ using 1 of 3 flexor tendon repair techniques. The techniques compared included the 4-strand Kessler repair, the cruciate repair, and the experimental Lahey repair (4-strand Kessler with cruciate modification). Biomechanical testing was conducted in order to obtain initial gap strength and ultimate tensile strength.

RESULTS

Although not significantly different from the 4-strand Kessler, the ultimate tensile strength of the Lahey repair was significantly greater than that of the cruciate repair.

CONCLUSIONS

The Lahey flexor tendon repair has significantly greater ultimate tensile strength than the cruciate repair. These findings suggest that the Lahey repair can be considered a biomechanically favorable 4-strand technique for the repair of flexor tendon lacerations.

A novel biomimetic material for engineering postsurgical adhesion using the injured digital flexor tendon-synovial complex as an in vivo model

BACKGROUND

Many surgical procedures are complicated by adhesions. These restrictive fibrotic bands form between normally separate gliding tissue layers, potentially impairing function. The authors tested the adhesion-modifying effect of a novel fibronectin-derived biomimetic biomaterial in a tendon-synovial complex injury model.

METHODS

The deep flexor tendons of digits 2 and 4 in the right forepaw of 15 New Zealand White rabbits were subjected to 5-mm-long partial tenotomies. Animals were randomized to receive biomaterial tubes enveloping the tendon injuries or left untreated. Digits, amputated at 2 weeks, were randomized to mechanical pullout assessments of adhesion strength or to quantitative histologic cellularity and immunohistochemical proliferation (Ki67) assessments.

RESULTS

The mean peak pullout force required to break the adhesions was reduced from 7.70 N (n = 6) in untreated digits to 0.31 N (n = 7) in biomaterial-treated digits (p = 0.001). The mean structural stiffness of the adhesions was also significantly reduced (p = 0.001). Histologically, treated and untreated digits demonstrated an equal incidence of adhesions. The treated adhesions were 55 percent less cellular at their surface than the untreated injured controls (p = 0.003). Treated tendons were 8 percent more cellular (with equal numbers of proliferating cells) at their surface and significantly more cellular within their bulk than positive controls (p <or= 0.05).

CONCLUSION

This study suggests a significant reduction in the restrictive nature of postsurgical adhesions following treatment with the antiadhesive biomaterial without compromising tendon cellularity.

Outcome of early active mobilization after extensor tendon repair

BACKGROUND

Traditionally the repaired extensor tendons have been treated postoperatively in static splints for several weeks, leading to formation of adhesions and prolonged rehabilitation. Early mobilization using dynamic splints is common, but associated with many shortcomings. We attempted to study the results of early active mobilization, using a simple static splint, and easy-to-follow rehabilitation plan.

MATERIALS AND METHODS

In a prospective study 26 cases of cut extensor tendons in Zone V to VIII were treated with primary or delayed primary repair. Following this, early active mobilization was undertaken, using an easy-to-follow rehabilitation plan. The results were assessed according to the criteria of Dargan at six weeks and one year.

RESULTS

All the 26 patients were followed up for one year. 20 out of 26 patients were below 30 years of age, involving the dominant hand more commonly (16 patients, 62%). Agriculture instruments were the most common mode of injury (13 patients, 50%). The common site for injury was extensor zone VI (42%, n = 11).

CONCLUSION

Rehabilitation done for repaired extensor tendon injuries by active mobilization plan using a simple static splint has shown good results.

An analysis of factors associated with failure of tendon repair in the canine model

PURPOSE

The canine model is commonly used for flexor tendon repair research. The purpose of this study was to analyze the factors, including laceration mode (partial and complete), suture techniques, therapy methods, and weight-bearing status, associated with tendon repair rupture or gap formation in the canine model in vivo.

METHODS

We reviewed the factors associated with repair failure among 624 flexor tendon repairs in zone II from 242 dogs reported previously from our institution, including both partial and complete lacerations.

RESULTS

We found that weight-bearing due to failure of postoperative immobilization was the most important factor influencing tendon repair rupture or gap formation.

CONCLUSIONS

As has been noted clinically, in our canine model failure and gapping of a flexor tendon repair was primarily the result of uncontrolled loading. Rehabilitation strategies that reduce the risk of catastrophic loading of the repair are critical to reducing the experimental failure rate when using dogs for flexor tendon research. Similar strategies may also reduce such failures in humans.

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.

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.

Flexor tendon suture: a description of two core suture techniques and the Silfverskiöld epitendinous suture

Flexor tendon injuries are commonly treated by orthopedic, plastic, and hand surgeons. Bunnell referred to zone 2 injuries as being in "no-man's land," plagued by poor results after surgical repair. Over the last 30 years, a better understanding of the biology of flexor tendon injuries, advanced surgical techniques, and perhaps most important, improved rehabilitation protocols, have afforded consistently good to excellent results after surgical repair at all levels of injury. Complications such as restrictive adhesions, joint contracture, and repair rupture, although less frequent, can compromise functional recovery.