Background:

Various techniques for joint preservation have been attempted in early stage of osteonecrosis of femoral head (ONFH), but the effects are still controversial. Recently, a combination therapy of core decompression (CD) and MSCs collected from bone marrow, adipocytes or human umbilical cord has been introduced, and satisfactory results have been reported. However, there is no study in which human umbilical cord-derived osteoblasts (hUC-O) were administered directly to the lesion in early ONFH. We have classified the location and size of lesions in early-stage ONFH, and will evaluate the hypothesis that the application of hUC-O is a safe and effective treatment.

Methods:

This is a prospective, single-center, phase I and open-labeled clinical trial. Nine patients with Association Research Circulation Osseous (ARCO) stage 1 or 2 ONFH will be assigned to a low-dose (n = 3, 1 ´ 10 7 hUC-O cells), medium-dose (n = 3, 2 ´ 10 7 cells), and high-dose group (n = 3, 4 ´ 10 7 cells) in the order of their arrival at the facility, and up to 18 patients will be enrolled depending on whether dose limiting toxicity occurs. We will perform CD on the participants, administer hUC-O according to the assigned group, and followed up for 12 weeks, including a total of 5 visits. This study will have 3 aims; first, to evaluate the safety of hUC-O through adverse events assessment, laboratory tests, vital sign assessment, physical examination, and electrocardiogram (ECG) test.; and second, to assess the clinical outcomes after hUC-O application by comparing pain visual analog scale (VAS), Harris Hip scores (HHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) before and after surgery; and third, to evaluate the radiographic results after hUC-O application by comparing extent of necrotic lesions according to the ARCO and Japanese Investigation Committee (JIC) classification on magnetic resonance imaging.

Discussion:

This clinical trial is a pilot phase 1 study evaluating the safety and efficacy of hUC-O local application combined with CD in early-stage ONFH patients. This study will provide the useful information on the treatment with hUC-O for those suffering from ONFH. Trial registration: Clinical Research Information Center (CRIS) established at the Korea Centers for Disease Control and Prevention (KDCA), KCT0006627. Registered 30 September 2021, https://cris.nih.go.kr/cris/search/detailSearch.do/20332