Greater Trochanteric Pain Syndrome, also known as GTPS (Greater Trochanteric Pain Syndrome) is a complex clinical condition characterized by chronic and recurrent pain in the lateral region of the hip, near the greater trochanter of the femur.

Biomechanical and anatomic-histologic interactions of the structures of the peri trochanteric space, in which, given the close anatomic-functional relationships, the origin can be traced to three different pathologic entities that may influence each other and fuel the progressive exacerbation of symptomatology. These are: external snap hip, trochanteric bursitis, and tendinopathies of the tendons of the gluteus mediums and gluteus minimums muscles.

Recent studies regarding GTPS have shown that in most cases this condition is due to degenerative tendinopathy of the tendons of the gluteus minimums and gluteus mediums muscles. Tendinopathy is defined as a pathological condition associated with histological changes that may result in a change in the organization of collagen fibrils, relative increase in the percentage of proteoglycans, glycosaminoglycans, and no collagenous components of the ECM accompanied by neo-vascularization and inflammatory state.

Tendinopathies thus result in painful symptomatology that very often also results in biomechanical functional deficit.

Clinically, GTPS presents as pain that is often debilitating and exacerbated by activities such as walking, climbing stairs, and lying on the affected side at night, associated with a progressive loss of stenia in hip abduction movements. On objective examination, a point of tenderness (trigger point) is noted at the level of the region of the greater trochanter, which may radiate to the lumbar area and along the lateral aspect of the thigh to the ipsilateral knee and a difficulty on strength versus resistance tests in hip abduction movements.

Although it is a very common syndrome, the treatment of painful grand trochanter syndrome, as well as that of tendinopathies in general, is still a major hurdle because the specific cellular pathogenetic and biomechanical etiopathogenetic mechanisms are still partly unknown and many treatments are empirical. Traditionally, the treatment of GTPS is initially conservative and includes rest, ice, NSAIDs and physiotherapy with stretching exercises of the fascia late. The use of corticosteroids, with systemic or local infiltrative intake, for the treatment of tendinopathies is highly controversial and, in any case, does not seem to have long-term efficacy.

MD-Tissue Collagen Medical Device is an injectable medical device based on porcine collagen type I; the collagen content is 100µg/2mL. Porcine collagen is like human collagen and highly compatible; it has very low risks of inducing adverse effects and is therefore used in several clinical settings.

This is a pilot monocentric Clinical Investigation based on a One sample design.

In the ex vivo study, MD-Tissue Collagen Medical Device was used as a substrate for cell cultures of human gluteal tenocytes on culture plates. The results suggest how MD-Tissue can induce an anabolic phenotype in tenocytes by stimulating their proliferation and migration; it would also be able to promote the synthesis, maturation, and secretion of COL-I, thereby promoting tendon homeostasis and repair. Specifically, the modification of gene expression and proteins involved in collagen turnover pathways were analyzed by real-time PCR, Slot blot and SDS-zymography. Data from the study showed that tenocytes cultured with MD-Tissue compared with controls exhibited increased secretion and migration of COL-1 increased mRNA levels of the matrix metalloprotease inhibitor proteins MMP-1 and TIMP-1.

The tenocytes used for the cell cultures were gluteal tenocytes, derived from human gluteal tendon fragments (obtained from subjects without any tendon pathology who had undergone total hip replacement surgery); therefore, it is reasonable to think that the porcine type I collagen-based compound may be a viable treatment in GTPS.

The results of the preclinical study suggest how MD-Tissue Collagen Medical Device can induce an anabolic phenotype in tenocytes by stimulating tenocyte proliferation and COL-I synthesis, maturation, and secretion, thereby promoting tendon repair. As these effects have been evaluated ex vivo on tenocytes of gluteal muscle tendons, the purpose of this study is to evaluate its efficacy in local infiltrative treatment, in the pertechnetic region, of GTPS, in terms of resolution of pain symptoms and recovery of stenia in abduction.

Variables will be assessed at 6 different times; at baseline (day 0), after week 1, weeks 2, weeks 6, weeks 10 and after weeks 24.

Inclusion Criteria:

• Male and female subjects aged 18 to 70 years;
• subjects with lateral palpatory pain that has appeared for at least 1 month;
• subjects with hip pain symptomatology assessed by Numerical rating scale (NRS) ≥ to 5;
• Subjects able to cooperate for the assessments in the Survey plan;
• subjects able to understand and sign informed consent.

Exclusion Criteria:

• subjects with true coxalgia (with positive FADDIR);
• subjects with ESHS (external snap hip syndrome);
• subjects already undergoing candidate hip replacement surgery;
• subjects with radiologic and clinical evidence of small and/or middle gluteal tendon detachment with indication for surgical repair;
• subjects with evidence of radiographically documented tendon calcifications;
• subjects with a degree of coxarthrosis of the hip that is a candidate for treatment according to the classification of Tonnis>1
• subjects who have taken fluoroquinolones within 30 days prior to enrollment
• subjects who have undergone treatment with hyaluronic acid or corticosteroids in the hip candidate for infiltrative treatment within 4 weeks before enrollment;
• subjects with local infections of the treatment candidate hip or systemic infections, osteomyelitis, or sepsis;
• subjects on chronic treatment with corticosteroids or immunosuppressants;
• subjects who are drug addicts, alcoholics, have psychiatric disorders, or have clinical conditions that may compromise the correct interpretation of PROMs or follow-up;
• subjects with coagulopathies, platelet aggregation disorders, or on treatment with oral anticoagulants or antiplatelets that cannot be discontinued during the study period;
• Pregnant and lactating subjects (female subjects of childbearing age should be tested for pregnancy before enrollment);
• subjects with allergy to porcine collagen.