Copyright © 2008 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Thomas A. Einhorn, MD*,
Department of Orthopaedic Surgery, Boston University Medical Center, Boston, Massachusetts
Posted October 2008
Sometimes things turn out better than expected. This study
tested the hypothesis that alpha-BSM (ETEX, Cambridge, Massachusetts, and
DePuy, Warsaw, Indiana), a bioresorbable calcium phosphate cement, is as
effective as autogenous iliac bone graft in the management of subarticular
tibial defects in patients who have sustained a tibial plateau fracture. The
results showed that alpha-BSM "appears to be a better choice, at least in terms
of the prevention of subsidence" for the treatment of these injuries.
The investigation involved twelve study sites in North
America, and bone defects were randomized to grafting with either autogenous iliac
bone graft or alpha-BSM calcium phosphate cement. Open reduction and internal
fixation was achieved with standard plate and screw or screw-only fixation. Patients
were evaluated at six to twelve months with regard to union, subsidence,
premature resorption, infection, functional recovery, and effect of tobacco
use. As all fractures united in both groups within the same time-period, there
was no difference between smokers and nonsmokers with regard to time to union
or frequency of union, and as there was no dissolution of either the bone graft
or alpha-BSM, the higher rate of articular subsidence in the autogenous iliac
bone-graft group combined with a slightly better range of motion in the alpha-BSM
group showed alpha-BSM to be the winner.
The authors suggested that the higher rate of articular
subsidence in the autogenous iliac crest bone-graft group was "an unexpected
finding." However, these results are very consistent with those of previous
studies that have demonstrated the benefits of a calcium-phosphate-based bone
cement in the augmentation of defects associated with fractures in long bones. Indeed,
a recent meta-analysis of randomized trials concluded that "the use of calcium phosphate
bone cement for the treatment of fractures in adult patients is associated with
a lower prevalence of pain at the fracture site in comparison with the rate in
controls (patients managed with no graft material). Loss of fracture reduction
is also decreased in comparison with that in patients managed with autogenous
bone graft."1 In fact, reports showing the benefits of calcium phosphate
cement in the treatment of displaced distal radial fractures2,3,
redisplaced distal radial fractures4,5, and unstable
intertrochanteric hip fractures6 have built a fairly substantial
body of evidence that the use of specific calcium phosphate cements in fracture
care may represent a technological advance in orthopaedic trauma surgery.
As with any new technology, use and application have to be
carefully monitored and results may not be generalizable to other sites.
Mattson and Larsson, two investigators who have extensively examined the
application of calcium phosphate cements in trauma surgery and reported
excellent results, demonstrated that when used to augment internal fixation of
displaced femoral neck fractures, calcium phosphate cement fails to improve
results7. Yet, in a study by Lobenhoffer et al.8, the use
of a calcium phosphate cement in the treatment of tibial plateau fractures
showed that the high mechanical strength of the cement allowed early weight-bearing
after a mean postoperative period of 4.5 weeks (range one to six weeks). As
most surgeons manage these fractures with longer periods of non-weight-bearing,
if these findings can be reproduced and if the use of calcium phosphate cements
can be demonstrated to consistently shorten the time needed for protected
weight-bearing, it may be possible to achieve improved outcomes, shorter
recoveries, and even better functional results in patients who sustain these
injuries. One point of caution, however, is to recognize that not all calcium phosphate
cements are the same. Different types form different mineral phases, and the
mechanical strength and dissolution properties may vary greatly. It is
important that the surgeon be familiar with the evidence that supports the use
of a specific calcium phosphate cement in the setting in which he or she intends
to employ it.
Calcium phosphate cements are not new, and trauma surgeons
have been slow to incorporate them into their clinical practices. Perhaps this
article, the recent meta-analysis by Bajammal et al.1, and a revisitation
to the now substantial body of literature supporting the use of calcium
phosphate cements will change that. Moreover, as surgeons become more adept and
experienced with the use of these materials, other applications, such as the
ability to employ a calcium phosphate cement as a delivery vehicle for a growth
factor, may be found. Indeed, alpha-BSM is currently being developed (and
chemically modified) in order to promote the use of recombinant human bone morphogenetic
protein-2 (BMP-2) as an injectable therapy9.
It is always pleasing when the results of a clinical
investigation show a positive finding that represents an opportunity for
further study and technological development. Perhaps the time has come to seriously
consider the use of calcium phosphate cements in orthopaedic trauma surgery and
to determine just how much of an advance they truly represent.
*The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity (Skeletal Kinetics [<$10,000] and Norian [>$10,000]). Also, a commercial entity (Norian) paid or directed in any one year, or agreed to pay or direct, benefits in excess of $10,000 to a research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which one or more of the authors, or a member of his or her immediate family, is affiliated or associated.
References
1. Bajammal SS, Zlowodzki M, Lelwica A, Tornetta P 3rd, Einhorn TA, Buckley R, Leighton R, Russell TA, Larsson S, Bhandari M. The use of calcium phosphate bone cement in fracture treatment. A meta-analysis of randomized trials. J Bone Joint Surg Am. 2008;90:1186-96.
2. Sanchez-Sotelo J, Munuera L, Madero R. Treatment of fractures of the distal radius with a remodellable bone cement: a prospective, randomized study using Norian SRS. J Bone Joint Surg Br. 2000,82:856-63.
3. Cassidy C, Jupiter JB, Cohen M, Delli-Santi M, Fennell C, Leinberry C, Husband J, Ladd A, Seitz WR, Constanz B. Norian SRS cement compared with conventional fixation in distal radial fractures. A randomized study. J Bone Joint Surg Am. 2003;85:2127-37.
4. Kopylov P, Adalberth K, Jonsson K, Aspenberg P. Norian SRS versus functional treatment in redisplaced distal radius fractures: a randomized study in 20 patients. J Hand Surg Br. 2002;27:538-41.
5. Kopylov P, Runnqvist K, Jonsson K, Aspenberg P. Norian SRS versus external fixation in redisplaced distal radial fractures. A randomized study in 40 patients. Acta Orthop Scand. 1999;70:1-5.
6. Mattsson P, Larsson S. Unstable trochanteric fractures augmented with calcium phosphate cement. A prospective randomized study using radiostereometry to measure fracture stability. Scand J Surg. 2004;93:223-8.
7. Mattsson P, Larsson S. Calcium phosphate cement for augmentation did not improve results after internal fixation of displaced femoral neck fractures: a randomized study of 118 patients. Acta Orthop. 2006;77:251-6.
8. Lobenhoffer P, Gerich T, Witte F, Tscherne H. Use of an injectable calcium phosphate bone cement in the treatment of tibial plateau fractures: a prospective study of twenty-six cases with twenty-month mean follow-up. J Orthop Trauma. 2002;16:143-9.
9. Seeherman H, Li R, Bouxsein M, Kim H, Li XJ, Smith-Adaline EA, Aiolova M, Wozney JM. rhBMP-2/calcium phosphate matrix accelerates osteotomy-site healing in a nonhuman primate model at multiple treatment times and concentrations. J Bone Joint Surg Am. 2006;88:144-60.
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