ESWT for ONFH was reported by Dr. Vulpiani et al. [11] in 2012 . The ESWT for treatment of 36 patients with ONFH was followed up at 3, 6, 12, and 24 months. The results were significantly associated with ARCO staging of the lesions after ESWT. Patients with early stage ONFH with ARCO stage I (100%) and stage II (81.8%) achieved excellent or good results than those in their late phase with ONFH with ARCO stage IIIa (26.7%) at follow-up (p < 0.005). Kusz demonstrated that ESWT resulted in considerable enhancement of quality of life in ONFH patients. Patients experienced pain reduction (visual analogue pain score decreased from 6.75 to 2.5) and increased mobility of the treated hip joint. Harris hip score increased from 55.21 to 89.21. However, they only followed up patients for 6 weeks [15]. In the same year, Wang et al. [16] reported long-term results of ESWT and core decompression in ONFH with 8- to 9-year follow-up. There were 48 patients with 57 hips in the study. The ESWT group consisted of 23 patients with 29 hips and the core decompression group had 25 patients with 28 hips. The functional results showed that 76% of hips were good or fair and 24% were poor after ESWT. On the other hand, 21% of hips were rated good or fair and 79% poor after core decompression. The results demonstrated that ESWT had better results than surgery in the treatment of early ONFH in long-term follow-up. Similar results were reported by Lee et al. [17]. They evaluated 24 patients with ARCO-staged ONFH in 32 hip joints that were treated with ESWT and follow-up from 1993 to 2012. The visual analogue scale scoring in group 1 (ARCO stages I and II) showed a median of 7–1.5 (p < 0.001) and group 2 (ARCO stage III) showed a mean of 7 to 4 (p = 0.056). In Harris hip score (HHS) analysis, group 1 showed significant improvement from 65.5 to 95 (p < 0.001), but the improvement was non-significant for group II (p = 0.280). The results indicated that ESWT was effective in early and mid-stage of ONFH. The largest patient population on this topic was reported by Gao et al. [18]. They showed a total of 335 patients with 528 hips treated with ESWT and followed up at 3, 6, and 12 months. The pain reduction (p = 0.00006) improved mobility of the treated hips (p = 0.00091), and bone marrow edema (p = 0.007) showed significant improvement after ESWT. The lesion size decreased after ESWT, but the differences were nonsignificant. Wang et al. [19] demonstrated that high dosage ESWT was more effective in the treatment of early-stage ONFH. They recruited 32 patients (42 hips) randomly and divided them into three groups. Group A (10 patients with 16 hips) received 2,000 impulses of ESWT at 0.510 mJ/mm2 to each hip. Group B (11 patients with 14 hips) and group C (12 patients with 12 hips) received 4,000 and 6,000 impulses of ESWT to each hip respectively. The high-dosage group C showed significant improvement in pain score (p = 0.037) and Harris hip score (p = 0.017) than group A and B at 6 month follow-up. One case report showed radial ESWT improved joint effusion, bone density for treatment of ARCO stage IV ONFH [20]. Additional studies are needed to clarify the use of radial ESWT with particular reference to ONFH.
The Synergistic Effect and Cocktail Therapy of ESWT in ONFH Treatments
In 2003, 4 healthcare workers including 3 women and 1 man with an average age of 26 years were affected by severe acute respiratory syndrome and were treated with a massive dose of corticosteroids that resulted in the development of early ONFH [21]. Those patients were treated with cocktail therapy that consisted of ESWT, HBO therapy, and alendronate. The practical applications of treatments were processed on 4 patients with 8 hips. First, each hip was treated with 6,000 impulses of shockwave at 0.62 mJ/mm2 energy flux density (EFD) in a single session. Then, HBO was performed once a day, 5 times a week for a total of 100 sessions. Patients received alendronate sodium 70 mg per week for 1 year. All patients returned to work as health care providers, and none of the hips required surgery during the 4 years follow-up period.
Fig. 2. The right hip before and after treatment showed the reduction of bone marrow edema and no further collapse; lesions of the femoral heads on MRI.
Our study also compared the effect of ESWT with and without alendronate for treatment of ONFH [22]. Hsu et al. [23] randomly divided forty-eight patients with 60 hips into group A (25 patients with 30 hips) and group B (23 patients with 30 hips). Group A was treated with 6,000 impulses of ESWT at 0.62 mJ/mm2 to the affected hip in a single session. Group B with ESWT received alendronate 70 mg per week for 1 year. Both groups showed significant improvement in pain and function of the hip (p < 0.001), but the differences between the 2 groups were nonsignificant (p = 0.400 and p = 0.313 respectively). In 2010, a comparison of cocktail therapy and ESWT alone was made in 63 patients (98 hips). The results showed that there was no difference between combined ESWT alendronate and HBO and ESWT alone to treat early ONFH. Therefore, the synergistic effects of ESWT, HBO, and alendronate treatments were not observed in short-term follow-up.
ESWT Treatment of ONFH in SLE Patients
The standard methods for the treatment of patients with SLE usually included long-term corticosteroid. Patients with chronic corticosteroids therapy often caused the ONFH [24, 25]. In 2006, Lin et al. [26] showed a case report that ESWT was used effectively in the treatment of ONFH with SLE caused by corticosteroids therapy. The result showed pain score (score = 0) and Harris hip score (score = 100) of bilateral hips of ONFH, reduced bone marrow edema, and no progression. Collapse of the lesions was observed on MRI (Fig. 2). In a further study, 39 patients including 15 SLE (26 hips) and 24 non-SLE (29 hips) with ONFH were enrolled for ESWT (0.62 mJ/mm2; 6,000 impulses) treatment. The results showed that the therapeutic effects showed no difference in pain score (p = 0.467) and Harris hip score (p = 0.194) between SLE and non-SLE patients.
Dosage Does Matter and Challenges in Future
Presently, there are limited data describing the dose effect of shockwave on the biomechanical properties of ONFH. Previous studies demonstrated a dose-related effect of ESWT in musculoskeletal disorder [27–29]. Kong et al. [14] investigated the application value of extracorporeal shockwave shock to repair and reconstruct osseous tissue for the treatment of ONFH by using energy density of ESWT from 0.18 to 0.25 mJ/mm2 in 36 patients with 42 hips. They found that ESWT had obvious therapeutic effects in the repairing and reconstructing osseous tissue and the hip Harris score and hip function had improved. Kusz et al. [15] assessed 9 patients with ONFH, ARCO stage I to III, treated by shockwave therapy with a dose of 1,500 pulses at an EFD of 0.4 mJ/mm2 and a frequency of 4 Hz at each point, which each patient receiving 4 points in the femoral head and 5 therapy sessions. After 6 weeks follow-up, the patients demonstrated pain reduction and improved mobility of the treated joint with considerable improvement in quality of life. The effectiveness of ESWT was to reduce pain and slow down the progression of bone damage in 36 patients with unilateral ONFH of ACRO stage I to III. Each treatment included four sessions, with 2,400 impulses each administered at 0.50 mJ/mm2 at 48–72 h