Contributions and Acknowledgements

A heartfelt thank you to Dr. Roberto Viganò, former Director of the Rheumatic Disease Surgery Unit, ASST Gaetano Pini – CTO – Milan, Italy, for his valuable scientific contribution and the experience lent during the drafting of this manual.

Guna S.p.a.



In recent years, the treatment of musculoskeletal disorders has evolved dramatically. Surgical and orthopaedic therapies have progressively dedicated greater attention to Biology and to repair and healing processes, increasingly favouring minimally-invasive techniques and the tissue sparing they afford.

Similarly, non-surgical treatments have followed this trend by focusing increasingly on the Biology of repair processes.

Within this scenario, collagen has become more and more important, and now plays a key role in everyday clinical practice.

Collagen, an element that is present in all the tissues of the musculoskeletal system, has proven to be a valuable ally in the treatment of many acute and chronic inflammatory or degenerative diseases, both with and without pain symptoms.

In Orthopaedics, the great attractiveness of injectable collagen lies in the fact that it can reactivate certain ‘dormant’ biological processes.

This is its greatest added value, especially (but not solely) in the treatment of chronic diseases, where it clearly proves its capability to induce and accelerate healing processes, precisely where other therapies have failed.

9 In Surgery – and not only in orthopaedic surgery – collagen is used as a biologically-active scaffold to induce repair responses or to promote new tissue formation processes. It can also be used in non-surgical treatments as a biologically-active scaffold where needed, in order to replace, support, strengthen and protect connective tissues using straight-forward injection techniques.

Guna Collagen Medical Devices are an innovative tool in all healing and repair processes. They are biologically active and also extremely well tolerated.

The special manufacturing process makes collagen completely fluid and therefore easily diffused within the tissues, which allows its use simply through deep or superficial injection techniques.

Moreover, apart from the product’s excellent tolerability, the possibility of combining collagen injections with physiotherapy and rehabilitation therapy makes it an outstanding aid for optimising these treatments, as well as pharmacological and surgical treatments, making it an excellent support for repair surgery and a synergistic booster for regenerative therapies.

As orthopaedic specialists, we now have a new therapeutic solution in the form of collagen-based medical devices which may allow us to overcome the partial or complete ineffectiveness of other therapies. The linear structure and ease of consultation of the Manual of Injection Therapy for the Musculoskeletal System make it a fundamental reference in orthopaedic clinical practice, a daily reference tool, a guide for younger colleagues, and a “good 10 companion” for all those colleagues who wish to acquire new skills in the field of injection techniques with Guna Collagen Medical Devices.


Musculoskeletal disorders (MSDs) are second only to mental and behavioural disorders in terms of their impact on global healthcare. Between 1990 and 2010, this group of disorders (including low back pain, neck pain, osteoarthritis, arthritis, osteoporosis, and other MSDs) was one of the most invalidating in terms of disability- adjusted life years (DALYs) and years lived with disability (YLDs).

Early diagnosis and appropriate treatment would lead to a reduction in disability and to an improvement in prognosis and life expectancy, with a consequent reduction in indirect costs, as the disability and the economic and social costs of managing MSDs are directly proportional to their stage of progression (https://www.epicentro.


The field of musculoskeletal disorders involves an extremely diverse range of pharmacological, physical rehabilitation and surgical interventions.

Over the past decade, there has been increasing interest and success of conservative treatments for musculoskeletal diseases, including those interventions aimed at repairing and regenerating musculoskeletal tissues, which are jointly referred to as Functional Tissue Engineering (FTE).

More recently, in the field of Functional Tissue Engineering, a new approach to painful musculoskeletal disorders is represented by bio-scaffolds of the extracellular matrix, containing porcine type I collagen and ancillary substances, to be administered by local injections.

The aim is twofold: on the one hand, the induction of repair and regeneration processes. On the other hand, and this is one of the most interesting aspects, a reduction of the time required for the functional recovery of the injured tissue, a matter of crucial importance in Orthopaedics, Sports Medicine, Physical and Rehabilitation Medicine.

GUNA COLLAGEN MEDICAL DEVICES represent a new approach in the field of Functional Tissue Engineering, with intra-articular and extra-articular injections of porcine collagen.



Guna Collagen Medical Devices are class III medical devices containing injectable collagen. They are classified and placed on the market in accordance with Directive 93/42/EEC of 1993.



Collagen accounts for 5-6% of adult body weight and is the most abundant protein in Mammals. Collagen is the fundamental constituent of ligaments, tendons, capsules, bones, cartilage, muscles, skin and, in general, of the extracellular matrix (ECM) (Boot-Handford and Tuckwell, 2003).

The smallest subunit of collagen is tropocollagen, which consists of sequences of glucose/galactose units and 4 amino acids (Proline, Hydroxyproline, Glycine and Lysine).

To date, 28 types of collagen have been identified (21 in Mammals), consisting of 46 separate polypeptide chains combined in different ways to give each type the required tissue-specific characteristics. All types of collagen have a characteristic triple-helix structure: the length of the helix and the width and the nature of the non-helical portion vary depending on the type of collagen (Silvipriya et al., 2015). Type I collagen is the most common. It can be isolated from skin, bone, teeth, tendon, and it is suitable for medical applications (Todhunter et al., 1994; Silvipriya et al., 2015).

Collagen is obtained by extraction and hydrolysis from various animal sources. Common sources of collagen for tissue engineering applications include bovine skin and tendons, porcine dermis, and equine tendons and dermis.

Porcine type I collagen

The collagen used in Guna Collagen Medical Devices is type I collagen of porcine origin, which is preferred to bovine collagen because it is structurally more similar to human collagen. At genetic level, the similarities between the two mammalian species Sus scrofa domesticus and Homo sapiens are remarkable. In fact, they have similar genome composition and size, and both genes and sequences are highly preserved in the two species. Nucleotide sequences, gene location, length and number of coding regions, and non-coding DNA content are just some of the genetic aspects that pigs and humans have in common.

Using porcine collagen guarantees high levels of safety on account of its very low immunogenicity: this makes it a material of choice also for numerous applications in aesthetic medicine, from the production of bio-scaffolds to dermal fillers (Catena et al., 2007; Narins et al., 2007; Solish, 2010; Sage et al., 2011; Brandão et al., 2013).

The glycoprotein sequences of chains a1 and a2 of human and porcine type I collagen show 97% and 94% homology, respectively.


Each vial of Guna Collagen Medical Device (2 ml) contains 100 μg of collagen.

In addition to collagen, each type of Guna Collagen Medical Devices contains different selected ancillary substances of vegetable, mineral or vitamin origin that support the mechanical action of collagen, with supporting activity.

This volume is focused on 7 different Collagen Medical Devices, which can be classified as “articular”

  • MD-HIP

and as “non-articular”



Due to the presence of hydrolysed type I collagen, Guna Collagen Medical Devices act as a bio-scaffold of the extracellular matrix. Following their locoregional injection, they act through the deposition of collagen fibrils in the damaged region (Milani, 2010). The collagen present in Guna Collagen Medical Devices is injected locally in order to replace, strengthen, structure and protect the tissues of the musculoskeletal system: it improves the anatomical and functional structure of the collagen fibres, of the structures containing them, and it provides mechanical support to the treated areas.

Guna Collagen Medical Devices have a mechanical action, due to an induced increase in the anisotropy (i.e. tensile forces) of the extra-cellular matrix (anisotropy depends on the integrity and the proper alignment of the collagen fibres). The local collagen supplementation improves anisotropy and increases tensile forces. It is known that the sub-fibrils constituting collagen fibrils express a certain degree of anisotropy when they are mechanically stressed (Wenger et al., 2007).

Restoring the anisotropy of collagen fibres through the local injection of Guna Collagen Medical Devices induces the same biological response that is achieved with eccentric exercise, typical of the phases of functional recovery from tendon injury. The signal induced by stimulating integrins causes the cascade of growth factors (TGF- beta 1, CTGF, IGF-1) required for the production of new collagen by the fibroblast (Silbernagel, 2011).

In an in vitro research study, tenocytes grown on a coating of type I collagen (namely MD-Tissue) showed a significant increase in tenocyte proliferation, and the synthesis and increased migration of type I collagen (Randelli et al., 2018).

The study suggests that the local injection of collagen is able to mechanically reactivate the fibroblast’s ability to synthesise new collagen, thereby inducing autologous repair and remodelling mechanisms in the damaged connective tissue. In addition, fibroblasts are able to generate tensile forces as well as receive them. These fibroblast contraction forces are essential for wound healing processes.

The main rationale of the “articular” Guna Collagen Medical Devices (MD-KNEE, MD-SHOULDER, MD-HIP, MD-SMALL JOINTS) is their action on chondrocytes.

The increase in tensile forces, generated by the injection of type I collagen, influences chondrocyte metabolism and is crucial for the structural integrity and functional efficiency of the cartilage (Millward-Sadler et al., 2004).

The integrins, present on the chondrocytes cell surface, convert the increased tensile forces into a biological response (integrin mechanotransduction effect) (Oesser et al., 2003; Siebert et al., 2010).

The neo-synthesis of type II collagen is one of the most crucial biological responses secondary to the effects of mechanotransduction. The neo-synthesis of type II collagen in the cartilage contributes to the structural recovery of the cartilage itself and, consequently, to the functional recovery of the joint.

The main clinical outcome of Guna Collagen Medical Devices is the improvement in the joint’s functional recovery by slowing the degenerative processes and promoting the repair processes of the joint.

This is supported by the clinical study A double-blind, randomised, active-controlled clinical trial on the intra-articular use of MD-KNEE vs. sodium hyaluronate in patients with knee osteoarthritis (“Joint Study”) published in 2016, which demonstrated the positive effects of MD-Knee on knee joint pain and function in patients with Kellgren- Lawrence grade II-III knee osteoarthritis (Martin Martin et al., 2016).

The main rationale of the mechanical action of the “non-articular” Guna Collagen Medical Devices (MD-TISSUE, MD-MUSCLE, MD- NEURAL), is their action on fibroblasts.

The main clinical outcome of Guna Collagen Medical Devices is the improvement in the functional recovery of soft tissues by slowing degenerative processes and improving the repair processes of the soft tissues.

The preclinical study Effect of a Collagen-Based Compound on Morpho-Functional Properties of Cultured Human Tenocytes, published in 2018, demonstrated the positive effects of MD-Tissue on the synthesis of type I collagen and on the modulation of its synthesis and degradation caused by MMPs (Metalloproteinases) and TIMPs (Tissue Inhibitors of Metalloproteinases). Another aspect of clinical interest is the centripetal migration of tenocytes

(belonging to the fibroblast family) to the wound area, which results in a reduction in wound width (Randelli et al., 2018).

Subsequently, the pre-clinical study The Collagen-Based Medical Device MD-Tissue Acts as a Mechanical Scaffold Influencing Morpho- Functional Properties of Cultured Human Tenocytes was published in 2020, highlighting the evident mechanical action of collagen medical devices (Randelli et al., 2020).

The paper Treatment of lateral epicondylitis with collagen injection: a pilot study, published in 2019, demonstrated the positive effects of MD-Tissue on the functional recovery of the elbow joint (Corrado et al., 2019).

Two clinical studies were published in 2020. The first one, Ultrasound-guided collagen injections for treatment of plantar fasciopathy in runners: A pilot study and case series, showed the positive effects of MD-Tissue in the treatment of plantar fasciitis (Corrado et al., 2020 a). The second one, Use of injectable collagen in partial- thickness tears of the supraspinatus tendon: a case report, reported the positive effects of MD-Tissue in the treatment of supraspinatus muscle tendon injuries (Corrado et al., 2020 b).

The clinical study Comparison between Collagen and Lidocaine Intramuscular Injections in Terms of Their Efficiency in Decreasing Myofascial Pain within Masseter Muscles: A Randomized, Single- Blind Controlled Trial, published in 2018, suggests the greater effects of MD-Muscle compared to Lidocaine 2% in controlling pain and muscle contracture in myofascial pain dysfunction syndrome in the masseter muscles (Nitecka-Buchta et al., 2018).

Another particularly interesting clinical study, Combination of in- situ collagen injection and rehabilitative treatment in long-lasting facial nerve palsy: a pilot, randomized, controlled trial, published in 2020, demonstrated the positive effects of using a mix of different collagen medical devices (MD-Muscle + MD-Neural + MD-Matrix) in the treatment of long-lasting facial nerve paralysis (Micarelli et al., 2020).


The immunogenicity and biocompatibility of collagen

Scientific literature supports the biomedical applications of type I collagen, based on the low immunogenicity and good biocompatibility of collagens, the origin and interspecies homology of the collagen (especially between human and porcine collagen), the therapeutic applications of collagen and the safety of porcine type I collagen. Type I collagen is suitable for implantation due to its high bioavailability and low immunogenicity. The great biocompatibility and inherent biodegradability of endogenous collagenases make exogenous collagen ideal for use in biomedical applications (Chattopadhyay and Raines, 2014; Tang and Saito, 2015; Deshmukh et al., 2016). An analysis of immunological data on the clinical use of collagens showed no evidence of adverse immunological responses induced by the collagens, regardless of their origin and the extraction methods used to obtain them (Lynn et al., 2004; Tang and Saito, 2015; Deshmukh et al., 2016).


From a clinical point of view, Guna collagen medical devices can be considered as extracellular matrix bio-scaffolds able to support the repair and regeneration mechanisms. Connective tissues can be deteriorated due to overuse, ageing or injuries causing pain symptoms in the musculoskeletal system.



  • Obtain patient’s informed consent.
  • Replace the needle used to draw the product from the vial with the specific needle for the injection to be performed.
  • Identify landmarks, to be marked using a dermographic pen if necessary.
  • Disinfect the skin thoroughly with iodopovidone or chlorhexidine, starting from the entry point to be used, progressively enlarging the disinfected with eccentric movements.
  • Use sterile gloves.
  • Apply a medicated patch onto the injection site.