In the present study, the clinical assessment data of 45 early stage ANFH patients who received CD plus β-TCP grafts with or without the application of PRP treatment from July 2015 to October 2020 was retrospectively analysed. Our study indicated that the application of PRP combining with CD and β-TCP grafts could significantly improve the symptoms and inhibit the progression of femoral head necrosis in the short term. Unfortunately, it did not significantly improve the rate of hip preservation.
The β-TCP material has been gradually studied and applied in ANFH because of their good biocompatibility, biodegradability, and osseointegration properties [24]. The β-TCP bio-ceramics grafts used in our study were designed and produced by Bio-Lu Biomaterial Co., Ltd. The pore size and interconnection diameter of the porous microstructure were optimized for a good compromise between angio-conductivity and mechanical property, which contribute significantly to the capacity of vascularization and osteogenesis. After implantation in the femoral head, the mechanical strength of the femoral neck and femoral head recovers gradually as the bio-ceramics degrade and new bone is formed, until the biomechanical support is fully restored.
Our team has achieved good results reporting an overall joint survival rate of 90.27% in the previous study of the application of bio-ceramic grafts prepared by β-TCP in the treatment of early femoral head necrosis [18].In our present study, the total hip survival rate was 86.2% at the mean time of 60 months follow-up. The overall survival rate were well-matched but the follow up time was much longer than the previous one. Wan et al. [22] compared the outcome of different bone grafts including the free fibular graft, the free vascularized fibular graft, autologous iliac bone, and β-TCP graft in early stage of ANFH. Satisfactory early-middle outcomes were shown in all the four bone graft implantation. However, as compared to other bone grafts, the β-TCP graft has the advantages of shorter operation time and lesser blood loss. In addition, the application of β-TCP grafts would not cause any damage to other parts of the body.
.PRP is defined as the plasma fraction of autologous blood with platelet concentrations above baseline. The normal platelet concentration is 200,000–450,000/ml. Studies have shown that clinical efficacy can be expected to increase by at least 4 times baseline (1 million/ml). Platelets play an important role in the normal healing response through the local secretion of growth factors and the recruitment of repair cells [25]. PRP may exert the beneficial effect in ANFH in the following ways: inducing angiogenesis and osteogenesis to accelerate bone healing, inhibiting inflammatory reactions in necrotic lesions, and preventing apoptosis induced by glucocorticoids [26, 27].
Theoretically, the CD combined with the β-TCP grafts provided the ‘land’ for the bone regeneration. For better healing, extra ‘fertilizer’–-PRP, is needed. Our study shows that the application of combining PRP with CD and β-TCP grafts can significantly improve the symptoms including VAS scores at 6 months (p < 0.01), HHS (p = 0.02) and inhibit the progression of femoral head necrosis in the short term with change in the modified Kerboul angle (p < 0.01) as compared with group A. Unfortunately, it does not significantly improve the rate of hip preservation at the finial follow up (p = 0.86).
Aggarwal et al. [25] conducted a prospective randomized double blinded comparative study in 40 early stage ANFH patients to investigate the efficacy of CD + PRP compared with CD alone, and the results showed that PRP use after CD provides significant pain relief, better midterm functional outcome, retards the progression, and enhances the survivorship free from reoperation for hip arthroplasty and femoral head collapse than CD alone. The survivorship from femoral head collapse in PRP + CD group/ CD group was 84%/68%. Compared with the CD + β-TCP group in our study, the survival rate in CD group was much lower, which indicates the significance of the mechanical support of β-TCP grafts and the adjuvant function of PRP.
In another study, Marco Grassi et al. [16] reported that core decompression combined with PRP could be indicated as a treatment for the I and II stages of ANFH in a prospective not controlled study The overall survival rate was 80% at two years follow up and 47% at five years follow up. Our hip-preserving strategy with the combination of CD + PRP + β-TCP presented better survival rate both at the two years and five years follow up.
In a prospective comparative study [28], forty-four patients (57 hips) with early ANFH were randomized into two groups: group A received CD, autologous bone marrow buffy coat (BBC) and β-TCP grafts; group B received treatment of CD with β-TCP grafts. BBC is obtained from bone marrow and it has stem cell activity to promote cell proliferation. The survival rate in group A was 95.5%, which is much higher than our results in PRP group. However, in this study, the patients age was much younger and the follow up time was relatively shorter than ours. Similar survival rate was reported in group B at the final follow up as compared to our study in CD + β-TCP group. Compared with BBC, the preparation of PRP is more minimally invasive and convenient.
Our result suggests that single-dose PRP effectively inhibits the progression of femoral head necrosis (modified Kerboul angle, p < 0.01), but also suggests that single-dose PRP may not be able to improve hip preservation rate, even with early stage ANFH. In the latest case report [29], the authors presented a case of ARCO IV glucocorticoid-induced ANFH received five consecutive ultrasound-guided intra-articular injections of PRP. Surprisingly, at 9-month follow-up, clinical and radiological reassessments demonstrated favorable outcomes. This case highlights the therapeutic potential of multiple times PRP injections for ANFH, even late-stage ANFH. At present, there is no relevant literature to propose a new solution. On the basis of the previous research, our team designed a femoral head implantation catheter technology (an invention patent has been applied for), hoping to achieve continuous input of PRP after CD to obtain better therapeutic effect and inhibit the progress of femoral head necrosis, and improve the hip preservation rate.
The results of the current series should be interpreted acknowledging certain limitations. Our study was retrospective without rigorous paired controls, and the strength of the evidence is limited. Second, the small sample size of this study still requires a large number of patients to support the further advantages of CD and β-TCP grafts combined with PRP. The specific location and size of the lesion were not analysed. In addition, some patients had bilateral disease; however, we analysed each hip independently. Study results may have been different if survival without THA, reoperation, or femoral head collapse was analysed for only one hip per patient.