Extracorporeal shock wave therapy for bone marrow edema syndrome in patients with osteonecrosis of the femoral head: a retrospective cohort study

Background There is now ample evidence suggesting that extracorporeal shock wave therapy (ESWT) can improve hip mobility and reduce pain in patients with osteonecrosis of the femoral head (ONFH). The ability of ESWT to cure bone marrow edema syndrome (BMES) in patients with ONFH, 12 weeks after the initial course of ESWT, needs to be verified further and more relevant clinical research-based evidence should be consolidated. This study aimed to evaluate the efficacy of ESWT for BMES caused by ONFH. Methods This retrospective cohort study included 67 patients with BMES caused by ONFH who were participating in a rehabilitation program as outpatients. Before and after ESWT, the area of femoral bone marrow edema was evaluated by magnetic resonance imaging (MRI), and the Harris score and Charnley score were evaluated as hip pain and function indicators. Results After ESWT, MRI revealed that the area of bone marrow edema decreased from 984.6 ± 433.2 mm 2 to 189.7 ± 214.4 mm 2 ( P < 0.0001). The Harris score increased from 42.2 ± 9.1 to 77.7 ± 10.8 points ( P < 0.0001). The Charnley score increased from 7.3 ± 1.4 to 12.0 ± 1.7 ( P < 0.0001). ESWT was effective in treating BMES in 98.5% of the cases. Conclusions This study demonstrated that ESWT can effectively treat BMES caused by ONFH and can aid in pain relief and functional recovery in patients with ONFH. Thus, ESWT should be included in the classic physical therapy regimen for patients with ONFH and BMES.