What tissue bankers should know about the use of allograft tendons and cartilage in orthopaedics

Allografts use in orthopedic surgery: trend change over the past 11 years from a regional tissue bank

Allografts are the second most transplanted tissue in medicine after blood and are now increasingly used for both primary and revision surgery. Allografts have the advantages of lower donor site morbidity, availability of multiple grafts, and shorter operative time. The Banks represents the bridge between Donor and Recipient and guarantees the quality and safety of the distributed allografts Given the increasing interest in these tissues, a retrospective analysis of data collected from the Regional Musculoskeletal Tissue Bank registry over an 11-year period (2009-2019) was conducted. The statistical analyses used were the Shapiro-Wilk normality test and a Poisson regression model. From January 2009 to December 2019, a total of 14,199 musculoskeletal tissues stored in the Regional Musculoskeletal Tissue Bank were provided for surgical allograft procedures. In 2009, the number of allografts performed was 925; this figure has steadily increased to 1599 in 2019. Epiphyses were taken as the reference tissue with an almost constant trend over the period, while a significant increase was denoted for extensor mechanism allograft, ligaments, tendons and long bone corticals (p < 0.001), processed bone tissues had no change in trend (p = 0.841). There was also a gradual decrease in the rate of microbiological positivity, as determined by bacteriological and serological tests performed on the collected tissues. This phenomenon is due to improved sampling techniques and the training of a dedicated team. Thus, we have seen how the use of allografts in orthopedic surgery has increased over the past 11 years, uniformly in terms of tissue type, except for the noticeable increase in ligamentous tissue.

Bilateral spontaneous quadriceps tendon rupture: a case report and literature review

Bilateral spontaneous quadriceps tendon rupture is a rare condition characterized by the simultaneous tear of the fibrous tissue connecting the quadriceps muscle to the patella bone. Prompt diagnosis is crucial for appropriate treatment and optimal outcomes. We present a case of a 70-year-old male with bilateral knee pain and an inability to walk, resulting from a trivial fall. Despite initial misdiagnosis, a thorough evaluation, including physical examination and imaging, revealed bilateral quadriceps tendon rupture. Surgical repair was performed, followed by a comprehensive rehabilitation program. At the four-month follow-up, the patient showed significant improvement in pain and function. This article provides a comprehensive review of the existing literature on bilateral quadriceps tendon rupture, emphasizing the challenges in the diagnosis and management of this rare condition. Early diagnosis, prompt surgical intervention, and a tailored rehabilitation program are crucial for successful outcomes.

Evaluation of Polycaprolactone-Associated Human Nasal Chondrocytes as a Therapeutic Agent for Cartilage Repair

Background

In this study, we manufactured a complex of human nasal septal cartilage (hNC) with polycaprolactone (PCL) for transplantation into cartilaginous skeletal defects and evaluated their characteristics.

Methods

Nasal septum tissue was obtained from five patients aged ≥ 20 years who were undergoing septoplasty. hNCs were isolated and subcultured for three passages in vitro. To formulate the cell-PCL complex, we used type I collagen as an adhesive between chondrocyte and PCL. Immunofluorescence staining, cell viability and growth in the hNC-PCL complex, and mycoplasma contamination were assessed.

Results

hNCs in PCL showed viability ≥ 70% and remained at these levels for 9 h of incubation at 4 °C. Immunostaining of the hNC-PCL complex also showed high expression levels of chondrocyte-specific protein, COL2A1, SOX9, and aggrecan during 24 h of clinically applicable conditions.

Conclusion

The hNC-PCL complex may be a valuable therapeutic agent for implantation into injured cartilage tissue, and can be used clinically to repair cartilaginous skeletal defects. From a clinical perspective, it is important to set the short duration of the implantation process to achieve effective functional implantation.

The biophysical characteristics of human composite flexor tendon allograft for upper extremity reconstruction

INTRODUCTION

Devastating volar hand injuries with significant damage to the skin and soft tissues, pulley structures and fibro-osseous sheath, flexor tendons, and volar plates pose a major problem to the reconstructive hand surgeon. Despite advances in tendon handling, operative technique, and postoperative hand rehabilitation, patients who have undergone flexor tendon reconstruction are often plagued by chronic pain, stiffness, and decreased range of motion with resultant decreased ability to work and poor quality of life. In this article, we expand the technique of human composite flexor tendon allografts (CFTAs), pioneered by Dr E.E. Peacock, Jr, which consist of both the intrasynovial and extrasynovial flexor digitorum superficialis and flexor digitorum profundus tendons and their respective fibro-osseous sheath consisting of the digital pulley structures, periosteum, and volar plates procured from cadaveric donors with the use of modern tissue processing techniques.

METHODS

Human cadaveric CFTAs were procured and divided into 2 groups-unprocessed CFTAs and processed CFTAs, which are cleansed and sterilized to a sterility assurance level of 10(-6). Physical length and width relationships as well as tensile strength and gliding resistance assessments were recorded pre-tissue and post-tissue processing. The histologic properties of the composite allografts were assessed before and after tissue processing.

RESULTS

There was no significant difference with respect to physical properties of the composite allografts before or after tissue processing. The processed composite allografts demonstrated equivalent maximum load to failure and elastic modulus compared to unprocessed tendons. The gliding resistance of the composite tendon allografts was not significantly different between the 2 groups.

CONCLUSIONS

The use of CFTAs addresses the issues of adhesion formation and lack of suitable donor material by providing a source of intrasynovial tendon in its unaltered fibro-osseous sheath without donor morbidity. This approach represents an important step toward designing an ideal material for complex flexor tendon reconstruction, which takes advantage of an intrasynovial flexor tendon in its native fibro-osseous sheath without the need for additional donor morbidity using a construct which can be engineered to have minimal tissue reactivity, negligible potential for disease transmission, and improved tendon healing properties versus standard tendon allograft.

Viral Inactivation of Human Osteochondral Grafts with Methylene Blue and Light

OBJECTIVE

Cartilage injury is one of the most common disorders of synovial joints. Fresh osteochondral allografts are becoming a standard treatment; however, they are supply constrained with a potential risk of disease transmission. There are no known virucidal processes available for osteochondral allografts and most methods presently available are detrimental to cartilage. Methylene blue light treatment has been shown to be successful in the literature for viral inactivation of fresh frozen plasma. The purpose of this study was to determine the capacity of methylene blue light treatment to inactivate a panel of clinically relevant viruses inoculated onto osteochondral allografts.

DESIGN

Osteochondral grafts recovered from human cadaveric knees were inoculated with one of the following viruses: bovine viral diarrhea virus (BVDV), hepatitis A virus (HAV), human immunodeficiency virus type 1 (HIV-1), porcine parvovirus (PPV), and pseudorabies virus (PrV). The samples were processed through a methylene blue light treatment, which consisted of an initial soak in nonilluminated circulating methylene blue at ambient temperature, followed by light exposure with circulating methylene blue at cool temperatures. The final titer was compared with the recovery control for the viral log reduction.

RESULTS

HIV-1, BVDV, and PrV were reduced to nondetectable levels while HAV and PPV were reduced by 3.1 and 5.6 logs, respectively.

CONCLUSIONS

The methylene blue light treatment was effective in reducing (a) enveloped DNA and RNA viruses to nondetectable levels and (b) nonenveloped DNA and RNA viruses of inoculated human osteochondral grafts by 3.1 to 5.6 logs. This study demonstrates the first practical method for significantly reducing viral load in osteochondral implants.

Physicochemical decellularization of composite flexor tendon-bone interface grafts

BACKGROUND

Extremity injuries involving tendon attachment to bone are difficult to address. Clinically, tendon-bone interface allografts must be decellularized to reduce immunogenicity. Composite grafts are difficult to decellularize because chemical agents cannot reach cells between tissues. In this study, the authors attempted to optimize tendon-bone interface graft decellularization.

METHODS

Human flexor digitorum profundus tendons with attached distal phalanx were harvested from cadavers and divided into four groups. Group 1 (control) was untreated. Group 2 (chemical) was chemically treated with 5% peracetic acid, 0.1% ethylenediaminetetraacetic acid, and 0.1% sodium dodecyl sulfate. Group 3 (low-power) underwent targeted ultrasonication for 3 minutes (22,274 J, 126W) followed by chemical decellularization. Group 4 (high-power) underwent targeted ultrasonication for 10 minutes (88,490 J, 155W) followed by chemical decellularization. Decellularization was assessed histologically with hematoxylin and eosin stain and stains for major histocompatibility complex I stains. Cell counts were performed. The ultimate tensile load of decellularized grafts (group 4) were compared with pair-matched untreated grafts (group 1).

RESULTS

Average cell counts were 100 ± 41, 27 ± 10, 12 ± 11, and 6 ± 11 per high-power field for groups 1, 2, 3, and 4, respectively (p < 0.001). Decellularization using physical and chemical treatments (groups 3 and 4) resulted in substantial reduction of cells and major histocompatibility complex I molecules. There was no difference in ultimate tensile load between treated (group4) and untreated (group 1) samples (p > 0.5).

CONCLUSIONS

Physicochemical decellularization of tendon-bone interface grafts using targeted ultrasonication and chemical treatment resulted in near-complete reduction in cellularity and maintenance of tensile strength. In the future, these decellularized composite scaffolds may be used for reconstruction of tendon-bone injuries.

Novel treatment of a failed quadriceps tendon repair in a diabetic patient using a patella-quadriceps tendon allograft

Recurrent quadriceps tendon rupture is a debilitating condition that may be challenging to treat, especially in the presence of systemic disease such as diabetes mellitus (Bedi et al., J Shoulder Elbow Surg 19:978-988, 2010; Chbnou and Frenette, Am J Physiol Regul Integr Comp Physiol 5:R952-R957, 2004; Chen et al., J Shoulder Elbow Surg 5:416-421, 2003). Many surgical treatment protocols have been proposed (Azar, in Canale and Beatty, eds., Campbell's Operative Orthopedics, Mosby/Elsevier, Philadelphia, PA, 2008; Ilan et al., J Am Acad Orthop Surg 3:192-200, 2003; Rodeo and Izawa, in Garrett et al., eds., Principles and Practice of Orthopedic Sports Medicine, Lippincott Williams & Wilkins, Philadelphia, PA, 2000). We report the case of a diabetic male with multiple treatment failures. He ultimately sustained a good outcome following treatment with a novel surgical technique that utilized a patella quadriceps tendon allograft. Tendon allograft-to-native bone healing had previously failed in this patient, so we used a bone-tendon construct allograft to provide an allograft bone-to-native bone healing site. Now, 13 months postoperative, the patient has increased strength, minimal pain, 20 ° of extensor lag and 130 ° of flexion.

Effect of hydrogen peroxide on human tendon allograft

Bacterial contamination of tendon allografts at the completion of processing has historically been about 2 %, with tendons that are found to be culture positive being discarded. Treatment of tendon allograft with hydrogen peroxide at the beginning of tissue processing may reduce bacterial contamination, however, the potential side effects of hydrogen peroxide treatment include hydrolysis of the collagen and this may alter the mechanical properties of the graft. Pairs of human tendons were used. One was washed in 3 % hydrogen peroxide for 5 min and the untreated tendon was used as a control. The ultimate tensile strength of the tendons was determined using a material testing machine. A freeze clamp technique was used to hold the tendons securely at the high loads required to cause tendon failure. There was no statistical difference in the ultimate tensile strength between the treated and untreated tendons. Mean strength ranged from Extensor Hallucis Longus at 588 Newtons to Tibialis Posterior at 2,366 Newtons. Hydrogen peroxide washing may reduce bacterial contamination of tendon allograft and does not affect the strength of the tendon.

Effects of ionizing radiation and preservation on biomechanical properties of human costal cartilage

Tissue banks around the world store human cartilage obtained from cadaveric donors for use in diverse reconstructive surgical procedures. To ensure this tissue is sterile at the time of distribution, tissues may be sterilized by ionizing radiation. In this work, we evaluate the physical changes in deep frozen costal cartilage (-70 °C) or costal cartilage preserved in high concentrations of glycerol (>98 %) followed by a terminal sterilization process using ionizing radiation, at 3 different doses (15, 25 and 50 kGy). Tension and compression tests were carried out to determine the mechanical changes related both to the different preservation methods and irradiation doses. For both methods of preservation, tension strength was increased by about 24 %, when cartilage tissue was irradiated with 15 kGy. Deep frozen samples, when irradiated with 25 or 50 kGy, had a decrease in their mechanical performance, albeit to a lesser extent than when tissues were preserved in high concentration of glycerol and equally irradiated. In conclusion, processing in high concentration of glycerol did not increase tissue protection against radiation damage; while cartilage preserved in high concentrations of glycerol withstands radiation up to 25 kGy, deep frozen human costal cartilage may be sterilized with a doses up to 50 kGy without significant mechanical impact.

Human flexor tendon tissue engineering: decellularization of human flexor tendons reduces immunogenicity in vivo

BACKGROUND

In mutilating hand injuries, tissue engineered tendon grafts may provide a reconstructive solution. We have previously described a method to decellularize cadaveric human flexor tendons while preserving mechanical properties and biocompatibility. The purpose of this study is to evaluate the immunogenicity and strength of these grafts when implanted into an immunocompetent rat model.

METHODS

Cadaveric human flexor tendons were divided into two groups. Group 1 was untreated, and Group 2 was decellularized by treatment with sodium dodecyl sulfate (SDS), ethylenediaminetetraacetic acid (EDTA), and peracetic acid (PAA). Both groups were then analyzed for the presence of major histocompatibility complexes by immunohistochemistry (IHC). Pair-matched tendons from each group were then placed into the dorsal subcutaneous tissue and anchored to the spinal ligaments of Wistar rats for 2 or 4 weeks, and harvested. The infiltration of B-cells and macrophages was determined using IHC. The explants where then subjected to mechanical testing to determine the ultimate tensile stress (UTS) and elastic modulus (EM). Statistical analysis was performed using a paired Student's t-test.

RESULTS

The decellularization protocol successfully removed cells and MHC-1 complexes. At 2 weeks after implantation, there was increased infiltration of B-cells in Group 1 (untreated) compared with Group 2 (acellular), both in the capsule and tendon substance. There was improved ultimate tensile stress (UTS, 42.7 ± 8.3 vs. 22.8 ± 7.8 MPa, p<0.05) and EM (830.2 ± 206.7 vs. 421.2 ± 171.3 MPa, p<0.05) in tendons that were decellularized. At 4 weeks, there was continued B-cell infiltration in Group 1 (untreated) compared with Group 2 (acellular). There was no appreciable difference in macrophage infiltration at both time points. At 4 weeks Group 2 (acellular) demonstrated persistently greater UTS (40.5 ± 9.1 vs. 14.6 ± 4.2 MPa, p<0.05) and EM (454.05 ± 101.5 vs. 204.6 ± 91.3 MPa, p<0.05) compared with Group 1 (untreated).

CONCLUSIONS

Human flexor tendons that were decellularized with SDS, EDTA, and PAA resulted in removal of cellular antigens and a decreased immune response when placed into Wistar rats. These grafts showed better mechanical properties at 2 and 4 weeks when compared with control tendons. Decellularization is an important step toward the use of tissue engineered flexor tendons in upper extremity reconstruction.

Skeletal tissue regeneration: current approaches, challenges, and novel reconstructive strategies for an aging population

Loss of skeletal tissue as a consequence of trauma, injury, or disease is a significant cause of morbidity with often wide-ranging socioeconomic impacts. Current approaches to replace or restore significant quantities of lost bone come with substantial limitations and inherent disadvantages that may in themselves cause further disability. In addition, the spontaneous repair capacity of articular cartilage is limited; thus, investigation into new cartilage replacement and regeneration techniques are warranted. Along with the challenges of an increasingly aging demographic, changing clinical scenarios and rising functional expectations provide the imperative for new, more reliable skeletal regeneration strategies. The science of tissue engineering has expanded dramatically in recent years, notably in orthopedic applications, and it is clear that new approaches for de novo skeletal tissue formation offer exciting opportunities to improve the quality of life for many, particularly in the face of increasing patient expectations. However, significant scientific, financial, industrial, and regulatory challenges should be overcome before the successful development of an emergent tissue engineering strategy can be realized. We outline current practice for replacement of lost skeletal tissue and the innovative approaches in tissue regeneration that have so far been translated to clinical use, along with a discussion of the significant hurdles that are presented in the process of translating research strategies to the clinic.