Key messages

• Instillation of bone marrow stem cells at the time of core decompression in osteonecrosis of the femoral head probably slows progression to osteoarthritis and may reduce the need for subsequent surgeries.
• It is unclear whether it has any effect on the functionality because the certainty of the evidence is very low.

What is the evidence.
See evidence matrix  in Epistemonikos later

We found two systematic reviews [1],[2] which included seven primary studies [3],[4],[5],[6],[7],[8],[9], two of them [3],[4], corresponded to randomized controlled trials. This table and the summary in general are based on the latter.

What types of patients were included

One study [4] included patients between 18 and 55 years of age with osteonecrosis of one or both hips stages IC to IIC according to the ARCO ( Association Research Circulation Osseous) classification with risk factors such as trauma, steroid use, alcohol abuse, Caisson disease or idiopathic aetiology (some patients had more than one cause).

The other randomized study [3] included patients without specifying age with osteonecrosis of one or both femoral heads ARCO stage I or II (without subtype specification), of varied aetiologies including traumatic, steroid use, alcohol abuse, Cushing's disease, pregnancy induced and idiopathic.

What types of interventions were included

Both studies included as intervention stem cells derived from bone marrow injected into the necrotic area through a tunnel of decompression. One study [3] used a concentrate of mononuclear cells derived from bone marrow obtained from iliac crest, in doses of 5x10⁸ cells (total mononuclear cell count). The second study [4] used mesenchymal stem cells obtained after two weeks of culture of concentrate mononuclear cells derived from bone marrow obtained from the sub trochanteric region of the affected femur at doses of 2x10⁶ cells (total mesenchymal stem cell count).

Both studies compared against core decompression alone

What types of outcomes
were measured

Harris Hip Score, progression to a more advanced stage according to ARCO classification, volume of necrotic area assessed by magnetic resonance, progression and need of vascularized bone graft or conversion to total hip arthroplasty.

We found three systematic reviews [5], [6], [7], including 14 studies   reported in 21 references [8], [9], [10], [11], [12], [13], [14], [15], [16],   [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28]. Eight   studies correspond to randomized controlled trials (15 references [9], [10],   [11], [12], [13], [14], [16], [17], [19], [21], [22], [23], [24], [26], [27]).   This table and the summary in general are based on the latter. One study [15]   did not contribute data to any of the outcomes of interest.

To whom this evidence does and does not apply

• This evidence applies to adult patients with diagnosis of osteonecrosis of femoral head of traumatic or atraumatic aetiology, in ARCO stages I or II.

• This summary considers functionality, progression to more advanced ARCO stages (III or IV ), and subsequent need of vascularized bone graft or need of total hip arthroplasty, outcomes considered critical for decision making by the authors of this summary.

• Since there is uncertainty about the benefits of stem cell therapy for osteonecrosis of femoral head, it is not possible to make an adequate risk/benefit balance .
• If the observed benefit were real, it would be an intervention with a very favorable risk/benefit ratio. 

• Stem cells therapy currently represents a high cost and limited access intervention, so it is likely that patients and physicians would not be inclined to use it, even more considering the existent uncertainty about its effects.
• It is not possible to determine whether it is a cost effective intervention that would generate long-term savings, because the certainty of the evidence regarding their benefits is poor.

Differences between this summary and other sources

• The key messages of our summary are partially consistent with the conclusions of the individual systematic reviews identified, which give a more optimistic conclusion, because of the weight given to observational studies included. They also highlight the proven benefits of stem cell therapy in preclinical studies.
• Our summary is consistent with the main clinical guidelines [10],[11] concerning the treatment of osteonecrosis of femoral head, where the need for prospective studies with documentation of the initial stage of disease, progression and time to total hip arthroplasty is suggested.

• The probability that future evidence change the key findings of this summary is high due to the limitations of the existing evidence .
• There are multiple ongoing studies that could provide relevant information for this question.