To the editor,
In our study(1), the two year survival rate was 50 % for the control
group (core decompression only) compared to 90 % in the bone marrow graft
group. Because of a small number of patients and the use of a 3 mm
inner diameter trephine, our results cannot be compared to large review
studies showing encouraging results with core decompression.
Concerning
the efficacy of core decompression, the optimistic conclusion of Radke et
al needs to be discussed. We found two randomized and controlled studies
on the effect of core decompression (2,3). In the first trial, 61 % of the
hips treated by core decompression did not show radiological progression
where as only 39 % had no radiological progression in the control group
(3). In the other study, the results were not in favour of core
decompression since 78 % and 79 % of the hips progressed to
subchondral fracture in the control and the core
decompression groups respectively, after 24 months of follow up (2).
For the classical
core decompression achieved with a 8 to 10 mm trephine (4), a meta-analysis
concludes that the efficacy of core decompression was only demonstrated
for stage 1 osteonecrosis (5) . Radke et al used a 2 mm
wire to make ten perforations into the necrotic area. This technique might
be interesting but is but not validated (6). To our knowledge, there are no data to prove that
such a method constitutes an "ideal technique".
The Association Research Circulation Osseous (ARCO) staging is a
classification principally based on X-Ray. Magnetic resonance imaging
(MRI) was added to assess preradiological stages. Furthermore, based on
publications from Japan and USA pointing out the prognostic value of the size and the position of the necrotic lesion, the ARCO Committee
added a subclassification using MRI and X-Ray for the location and the
quantification of the lesion (7). However, the ARCO staging has never been
validated. So far, only the classification of Steinberg was validated
except for the subclasses A, B, C used to quantify the lesion (8). In our
study, the location of the osteonecrotic lesion in relation to the weight
bearing portion of the femoral head was measured by MRI and was comparable
in the two groups at baseline. The volume of the lesion and of the femoral
head was measured by drawing the contours of the necrotic lesion on each 3
mm coronal T1 weighted slice. Those measurements can not be compared to
those reported in other studies (8-10). However, Hernigou et al compared
the volume of the osteonecrotic lesion in stage 3 osteonecrosis to the
anatomical measurements of the femoral heads using the same technique as
ours (11). Like us, they demonstrated the accuracy of the measurement of the
volume of the lesion using this technique. Moreover, since the volume of
the lesion was similar at baseline in both groups, it could not have
interfered with the outcome.
References
(1) Gangji V, Hauzeur JP, Matos C, De M, V, Toungouz M, Lambermont
M. Treatment of osteonecrosis of the femoral head with implantation of
autologous bone-marrow cells. A pilot study. J Bone Joint Surg Am 2004; 86
-A(6):1153-1160.
(2) Koo KH, Kim R, Ko GH, Song HR, Jeong ST, Cho SH. Preventing
collapse in early osteonecrosis of the femoral head. A randomised clinical
trial of core decompression. J Bone Joint Surg Br 1995; 77(6):870-874.
(3) Stulberg BN, Davis AW, Bauer TW, Levine M, Easley K.
Osteonecrosis of the femoral head. A prospective randomized treatment
protocol. Clin Orthop 1991;(268):140-151.
(4) Ficat P, Arlet J, Vidal R, Ricci A, Fournial JC. [Therapeutic
results of drill biopsy in primary osteonecrosis of the femoral head (100
cases)]. Rev Rhum Mal Osteoartic 1971; 38(4):269-276.
(5) Castro FP, Jr., Barrack RL. Core decompression and conservative
treatment for avascular necrosis of the femoral head: a meta-analysis. Am
J Orthop 2000; 29(3):187-194.
(6) Radke S, Kirschner S, Seipel V, Rader C, Eulert J. Magnetic
resonance imaging criteria of successful core decompression in avascular
necrosis of the hip. Skeletal Radiol 2004; 33(9):519-523.
(7) Gardeniers JWM. ARCO (Association Research Circulation Osseous)
committee on terminology and classification. ARCO News 1993;(5):79-82.
(8) Steinberg ME, Hayken GD, Steinberg DR. A quantitative system for
staging avascular necrosis. J Bone Joint Surg Br 1995; 77(1):34-41.
(9) Cherian SF, Laorr A, Saleh KJ, Kuskowski MA, Bailey RF, Cheng
EY. Quantifying the extent of femoral head involvement in osteonecrosis. J
Bone Joint Surg Am 2003; 85-A(2):309-315.
(10) Koo KH, Kim R. Quantifying the extent of osteonecrosis of the
femoral head. A new method using MRI. J Bone Joint Surg Br 1995; 77(6):875
-880.
(11) Hernigou P, Lambotte JC. Volumetric analysis of osteonecrosis
of the femur. Anatomical correlation using MRI. J Bone Joint Surg Br 2001;
83(5):672-675.
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