Radiofrequency ablation (RFA) was first introduced for treating knee osteoarthritis (OA) in 2010 and has emerged as a minimally invasive treatment option. Three RFA techniques have been adopted for treating knee OA, including conventional, pulsed, and cooled RFA. However, the efficacy among different RFA techniques in the treatment of knee OA is still unclear. Three electronic databases were systematically searched for relevant articles, including PubMed, Embase, and Cochrane Library. A meta-analysis of articles that investigated the use of RFA techniques in the treatment of knee OA was conducted to pool the effect size in pain before and after treatment. A total of 20 eligible articles (including 605 patients) were included for our meta-analysis. After treatment, the patients had significant improvements in pain for all three RFA techniques when compared with the baseline level for the 1, 3-, and 6-month follow-ups (p < 0.00001). However, there were no significant differences in the efficacy among the three RFA techniques for all follow-up visits (p > 0.05). The three RFA techniques demonstrated a significant improvement in pain for up to 6 months after treatment. Comparing the efficacy of the three RFA techniques in the treatment of knee OA, our results showed that no significant differences in pain relief among the three RFA techniques were observed at the 1-, 3-, 6, and 12-month follow-up visits.

We report two rare cases of femoral neck fracture resulting from osteonecrosis of the femoral head (ONFH) that was undiagnosed at the patients’ initial visits. The patient in the first case had sequential bilateral displaced femoral neck fractures. Because no osteonecrosis of the femoral head was visible on X-ray film and the data of liver function tests were normal, ONFH was not diagnosed. In addition, because the patient was a 55-year-old man with normal everyday functioning, closed reduction with cannulated screws was performed at both visits. Nine months later, he came to our outpatient department with bilateral hip pain; X-rays revealed nonunion and implant failure at both hips. The patient subsequently underwent bilateral total hip arthroplasty (THA) and had a satisfactory outcome at his 4-year follow-up. The patient in the second case had a left displaced femoral neck fracture after trivial trauma two months prior. ONFH was not diagnosed upon examination of X-ray findings. The patient was 52 years old with liver cirrhosis and had bipolar hemiarthroplasty performed because of a chronic displaced fracture and poor general condition. After 2 years, she began to have right hip pain. X-rays revealed massive necrosis and sclerosis of the femoral head. Computed tomography scans for ONFH staging revealed impending fracture lines at the subcapital site of the patient’s previous left femoral neck fracture. Right THA was then performed, and the outcome was satisfactory.