The treatment for ONFH includes hip arthroplasty, hip preservation surgery and conservative management. THA has been considered as the ultimate option for end-stage osteoarthritis (OA) secondary to femoral head collapse[32], which can relieve pain and get better function of hip. But, the age of ONFH is mostly between 30 and 50 years old, and hip arthroplasty cannot meet some requirements for the young adults, such as service life of the prosthesis. On the other hand, hip arthroplasty may have complications that the surgeons concern mostly, such as infection, prosthesis loosening, periprosthetic fracture and so on, which are risks for revision. For early-stage ONFH, pain relief and preservation of the autologous hip are still an important choice, so there are a lot of hip salvage surgery[14]. However, pain relief and hip survival remain a challenge for orthopedic surgeons. There is no consensus on the strategy for hip-preserving surgery in the current guidelines.
Core decompression, one of the most commonly surgery used for hip preservation of ONFH, is to reduce intramedullary pressure, thereby preventing neurovascular compression and promoting new bone formation[33], and some studies[11, 13], compared core decompression and conservative management, have proved its effective. In order to increase its efficacy, there are modified versions, including the improvement of methods and combined with bone graft (autologous or allogeneic), mesenchymal stem cells and so on. It was reported[34, 35] that Arthroscopic management in the process of core decompression with additional treatments was viable and had significant advantages. Hu B et al[36], in the study to investigate the efficacy of fibula fixation in the treatment of early-stage ONFH, found that fibula fixation could effectively relieve the joint pain in patients with early ONFH, but it was not superior to core decompression in preventing articular surface collapse. Martinot et al[37] reported that augmented core decompression (combined with adjuvant therapy) was significantly better than core decompression alone in 2-year survival and the long-term survival (without arthroplasty). Similar results were reported treatment with modified core decompression[15–17, 38]. Nonetheless the clinical outcomes have varied widely[39]. However, other studies reported[40–43] that core decompression combined with adjuvant therapy can improve the symptoms of pain, but it did not affect the progress and collapse of femoral head, especially in the late stage of ONFH. So, there is still controversial about core decompression (with or without adjuvant therapy) for ONFH.
As one of the adjuvant therapies, platelet-rich plasma, with the advantages of cheap, simple and less complications,is effective in the treatment of ONFH. Victor Ibrahim et al[44] reported a case of ONFH with autologous PRP injection. The patient demonstrated significant functional improvements after 1-year follow-up. Some animal experiments[45, 46] also confirmed the effects and illustrated the mechanism of PRP. PRP promoted beneficial effects by inducing angiogenesis and osteogenesis to accelerate bone healing, inhibiting inflammatory reactions in necrotic lesions, and preventing apoptosis[18]. Samy et al.[47] found that, with a mean follow-up of 41.4 ± 3.53 months in a prospective study, core decompression combined with PRP and collagen sheet in the treatment of ONFH, the Harris hip score increased from 46.0 ± 7.8 preoperatively to 90.28 ± 19 at final follow-up. The mean values of VAS decreased from 78 ± 21 to 35 ± 19, with an average decrease of 43 points. Therefore, in patients with ONFH, the use of PRP with collagen after core decompression can relieve pain and improve function. It was reported that by Grassi et al[48], with 22 patients (30 hips) of ONFH, including Ficat Ⅰ-ⅡA-ⅡB, Harris hip score improved from 64 points before operation to 84 points two years later. At the end points of THA, the hip survival rates were 100% in stage Ⅰ, 67% in stage ⅡA and 0% in stage Ⅱ B after follow-up for 5 years. Therefore, core decompression combined with PRP in the treatment of ONFH, the earlier the treatment, the better the benefit may be. In addition, some studies[49, 50], core decompression combined with mesenchymal stem cells, bone grafting, PRP in the treatment of early ONFH, reported good preliminary results.
In this study, we conducted a meta-analysis of 10 selected studies to corroborate the efficacy of PRP combined with core decompression bone grafting in the treatment of ONFH. To ensure a reliable conclusion, previously published studies were retrieved, reviewed and summarized to answer various clinical questions of this malady. Overall, our results show that the use of PRP combined with core decompression bone grafting can significantly improve the symptoms, may delay the progression (or collapse) of femoral head and THA. For the analysis of progression and THA, it should be noted that the articles included in the analysis were relatively few and the time of follow-up was insufficient, and on the other hand, the articles included in the analysis only described the number of progression and THA at the final follow-up, but did not specify the time of progression and THA, which might affect the result. So, it was not clear whether the use of PRP delayed progression and THA. In addition, the sensitivity analysis did not indicate significant influence on the overall results. The publication bias was found by the visual distribution of funnel plots, but it did not indicate publication bias by Begg's and Egger's tests (P = 0.118).
Limitations
The meta-analysis contains the following limitations. First, the studies included in this analysis is insufficient, and potential publication bias may exist. Second, this study just includes references in English and Chinese. Therefore, we may have lost data from those in other languages. Third, the references included have a lot confounding factors and we cannot adjust for the confounding factors, such as the etiology and stages of ONFH, different amounts of PRP et cetera. Forth, the time of follow-up is different in the included studies, so it cannot evaluate the long-term efficacy, and there is a high heterogeneity. Therefore, we should be cautious about the conclusions of the meta-analysis. In all, the quantity and quality of the included studies in this meta-analysis still need to be improved. So, the conclusions of this study need to be fully verified by more large-sample multicenter prospective clinical studies.