gms | German Medical Science

One important task of traumatology is to enhance fracture healing after accidents. A traumatic fracture is one in which a break in the continuity of the bone occurs as the result of a high-force impact and not as the consequence of a medical condition that weakens the bones.

According to the Federal Statistical Office of Germany, bone fractures ranked among the 20 most frequent principal diagnoses and bone grafting among the 50 most commonly performed inpatient procedures in 2008.

Fracture healing is classified as delayed when bone building is incomplete more than four months after injury (delayed union), and as failed if still incomplete after six months (nonunion) in spite of treatment. Autogenous iliac crest bone graft is currently the standard procedure used to enhance fracture healing in patients with defects of certain sizes or nonunions. Because harvesting bone graft requires an additional operation, it is an expensive procedure. Moreover, only limited amounts of bone can be harvested, and several complications like pain and infection at the donor site can occur.

Several bone graft substitute materials of human (allogenous), animal (xenogenous) and synthetic origin are increasingly discussed as alternatives to autologous bone grafting and standard care without bone grafting. Some innovative approaches in the field of tissue engineering as well as growth factor applications have also to be considered.

Despite the high relevance of the topic, a systematic assessment of the different bone graft substitutes on the basis of high quality studies is still lacking. The current health technology assessment (HTA) aims to close this gap and provides an evidence-based review of the topic.

• What evidence on the efficacy of bone graft substitutes is available?
• What is the efficacy of bone graft substitutes in the treatment of traumatic fractures?

• What evidence on cost-effectiveness of bone graft substitutes is available?
• What is the cost-effectiveness of the use of bone graft substitutes in the treatment of traumatic fractures?

• Which ethical, social and legal implications are associated with the use of bone graft substitutes for the treatment of traumatic fractures?

A literature search was conducted in electronic medical databases (MEDLINE, EMBASE, BIOSIS, ETHMED, INAHTA, NHS-CRD-DARE and Cochrane database etc.) in December 2009 and was completed by hand searching publications in the reference lists of the relevant articles. The search was restricted to publications in the languages German and English but was not restricted by date. The literature search hits were screened in three steps. The first step was limited to analysis of the titles of the literature hits, the second to the summaries, and the third to the complete publications. Two independent reviewers were involved in the selection of the relevant publications.

Randomised controlled trials (RCT) comparing the treatment of traumatic fractures (in adults without relevant pre-existing bone diseases) with and without bone graft substitutes or comparing different bone graft substitutes were included in the analysis. Studies published only as abstracts were excluded.

All data were extracted in the same manner using a data extraction sheet. Critical appraisal of study quality was performed adopting the Cochrane Risk of Bias Tool.

For information synthesis, the results of the studies were summarized descriptively and, if appropriate, study results were combined in metaanalyses. Metaanalyses were performed using the random effects model with a 95% confidence interval (CI), statistical heterogeneity was assessed.

Publications with health economic analyses on the basis of RCT comparing the treatment of traumatic fractures in adult patients with or without bone graft substitutes use or comparing treatments with different types of bone graft substitutes use were included into the evaluation. The medical assumptions used in the identified health economic analyses were compared with the results of the medical evaluation of this review. The economic assumptions were assessed on their transferability to the current situation in Germany.

Information synthesis of the results of the evaluated health economic analyses was performed qualitatively.

A systematic literature search was carried out to find publications explicitly addressing the ethical, social and/or legal implications of the use of bone graft substitutes.

The literature search yielded 1,998 hits, including 13 studies eligible for inclusion in the medical evaluation. The hand search identified another study, bringing the total number of included studies to 14.

Only few or even single studies on the use of different bone graft substitutes were found. Some of the studies differed significantly in terms of the technologies used, and had to be analysed separately. Bone morphogenetic protein (BMP) was the only type of bone graft substitute used for the treatment of nonunions.

Three studies on the use of BMP for fracture healing (all with an elevated or high risk of bias) were eligible for analysis. All three were limited to fractures of the tibia.

The comparison of BMP-2 versus standard care without bone grafting showed significant differences in favour of BMP-2 in terms of the outcomes fracture healing at the end of the study (relative risk [RR] 1.41; 95%-confidence interval [CI] 1.14 to 1.76) and fracture healing requiring secondary intervention (RR 0.56; 95 %-CI 0.40 to 0.78), and in terms of the complications hardware failure (RR 0.51; 95 %-CI 0.29 to 0.88) and pain (RR 0.86 95%-CI 0.74 to 0.99).

The comparison of BMP-2 with autogenous bone grafting revealed no significant difference between the two groups.

The comparison of osteogenic protein (OP)-1 with autogenous bone grafting, based on evidence from only one small study, also revealed no significant difference between the two groups (data only available for the outcome fracture healing).

The three studies included in the metaanalysis (all with a high risk of bias) compared OP-1 with autogenous bone grafting for treatment of nonunions. Two investigated nonunions of the tibia, and the third nonunions of the distale radius. The metaanalysis revealed a significant difference in favour of OP-1 in terms of the outcome hardware failure (RR 0.69; 95%-CI0.49 to 0.98), but no significant differences for the other outcome measures.

Four studies (all with a high risk of bias) on the use of calcium phosphate (CaP) cement for fracture treatment were included in the analysis. One was limited to fractures of the distal radius, one to multiple fractures of the long bones and calcaneus, one to tibial plateau fractures, and one to fractures of the calcaneus. The results of the latters study were not included in the data synthesis due to the use of different outcome measures.

In comparison with standard care without bone grafting, CaP cement (RR 0.16; 95 %-CI 0.06 to 0.45) demonstrated a significant advantage in terms of the complication infection, but achieved no significant difference in terms of the two other outcome measures, secondary loss of reduction and pain.

The comparison of CaP cement versus autogenous bone grafting revealed a significant difference in favour of CaP cement for the outcomes secondary loss of reduction (RR 0.33; 95 %-CI 0.15 to 0.72) and pain (RR 0.63, 95 %-CI 0.42 to 0.95) and no significant difference for the outcomes fracture healing and infection.

Two studies on the use of composite materials containing bone marrow aspirate for fracture treatment (both with a high risk of bias) were included in the analysis. Both addressed fractures of the long bones and had a high risk of bias. One study evaluated the collagen-CaP-based bone graft substitute Collagraft® mixed with autogenous bone marrow, and the other investigated the demineralised bone matrix (DBM)-based material Grafton® mixed with autogenous bone marrow. Both studies used autogenous bone grafting as a comparator. The metaanalysis revealed no significant differences between the study groups in terms of the outcomes secondary loss of reduction and fracture healing. Significant differences in the outcome measures infection (RR 0.36; 95 %-CI 0.17 to 0.75) and pain (RR 0.78; 95%-CI 0.62 to 0.98) in favour of composite materials containing bone marrow aspirate were detected in one study.

Of the two studies eligible for inclusion, one (high risk of bias) compared porous hydroxyapatite bone graft substitute material to autogenous bone grafting material in tibia plateau fractures. No significant differences between the two groups were detected at radiological or clinical follow-up. Also, there was no significant difference between the groups regarding the outcome measures loss of reduction, hardware failure or infection.

The second study (high risk of bias) compared the use of autogenous Tutoplast® bone chips with autologous bone grafting for treatment of fractures of the distal radius. There was no significant difference between two groups in terms of the total success rate. The only significant advantage of the bone graft substitute was a reduction of pain (RR 0.25 95 %-CI 0.08 to 0.85).

The literature search yielded 134 hits. One health economic analysis identified in the systematic literature search and another identified in the hand search were included into the evaluation.

Both health economic analyses were based on the randomised BESST study (with an elevated risk of bias) comparing the effects of BMP-2 on a collagen carrier in addition to standard care without bone grafting versus standard care without bone grafting alone in patients with open fractures.

Both analyses addressed the endpoints time to fracture healing, revision rate due to delayed facture healing, and the rate of infections. The cost assumptions in the analyses were based on conditions in Germany (2005) or the United Kingdom (2003 to 2007).

The use of BMP-2 in addition to standard care (without bone grafting) led to increased costs considering all patients with traumatic open fractures. However, cost savings through the additional use of BMP-2 were estimated in a patient subgroup with high-grade open fractures (Gustilo-Anderson grade IIIB). The estimated cost savings from the health insurance perspective in the high-grade Gustilo-Anderson grade III-B injuries were found to be 2,800 euros (evidence of low-grade quality). The cost-effectiveness of BMP-2 has not been proven. The cost-effectiveness for the use of BMP-2 as an alternative to standard care with bone grafting as well as for the use of other bone graft substitutes in fracture treatment have not been determined.

No studies on the ethical, social and legal aspects of the use of bone graft substitutes for treatment of fractures or nonunions could be identified.

All of the studies reviewed suffer from methodological flaws of varying degrees. Due to the very broad scope of the report and despite building subgroups the studies tended to be rather clinical heterogeneous, limiting the ability to pool the data.

In more than 50% of the studies, the sequence generation, allocation concealment, baseline comparability and intention-to-treat-principle are at least questionable. The same applies to blinding and the adequacy of reporting drop-outs. Furthermore, most of the studies had a small sample size and very few demonstrated an adequate sample size calculation. Non-significant results may have been attributable to small sample size.

Since the methodological quality of most of the studies is poor, the results should be interpreted with caution. Many of the studies and corresponding publications were sponsored by manufacturers. A lack of significant difference does not necessarily imply equivalent efficacy of the alternative treatments.

Due to the aforementioned methodological limitations of the study on BMP-2 versus standard care without bone grafting, the significant differences in some endpoints should not be interpreted as proof but merely as suggestive of efficacy.

The low study quality had an even greater impact on the strength of evidence regarding the use of CaP cements and composite materials containing bone marrow. Therefore, the few endpoints showing significant differences in favour of bone graft substitutes are interpreted as being only weakly suggestive for efficacy.

The transferability of the results to the German health system is considered to be good. However, the generalisability of the results to patients with other baseline characteristics is limited.

As mentioned in the medical assessment, the RCT underlying for the health economic studies show a number of methodological limitations. Several clinical assumptions used in the analyses are not clearly comprehensible. The currency and transferability of the results to the up-to-date situation in Germany from the societal perspective is limited.

Furthermore, the view on the performed analyses from the societal perspective is also limited due to missing data on rehabilitation costs, loss of productivity due to sick leave, and intangible costs.

Participatory decision-making between the physician and the patient regarding the choice of treatment requires a detailed information of the patient on the lack of long-term data (concerning immunological changes etc.), especially when the use of BMP is considered. In particular, the off-label use of bone graft substitutes containing growth factors (e.g. BMP) could have legal implications due to the risk of complications such as unwanted tissue proliferation at other sites.

The use of different types of bone graft substitutes in the treatment of fractures or nonunions has to be analysed in a sophisticated way. The evidence and the quality of the data are poor.

From a medical point of view, the use of BMP-2 is a viable alternative for treatment of open fractures of the tibia, especially in cases where bone grafting is not possible.

Autologous bone grafting is preferable to osteogenic protein-1 for the treatment of fractures and nonunions.

The use of CaP cements should be considered carefully in each clinical situation, since advantages in the outcome secondary loss of reduction and pain may arise compared with bone grafting.

The same applies to the use of composites containing bone marrow, which may improve the outcomes infection and pain. The use of the hydroxyapatite material and the allograft bone chips compared to autologous bone grafts cannot be recommended at present. The results of the conducted metaanalysis can only be transferred to patients with fractures or nonunions similar to those addressed in the included studies.

From a health economic perspective, the use of BMP-2 in addition to standard care without bone grafting is recommended as cost-saving in patients with high-grade open fractures (Gustilo-Anderson grade IIIB injuries). The grade of this recommendation is weak due to the high uncertainty of cost parameters and the low strength of evidence regarding clinical advantages. No recommendations can be made from a health economic perspective regarding the use of BMP-2 as an alternative to standard care with bone grafting as well as for the use of other bone graft substitutes in patients with fractures.

From an ethical and legal point of view, patients should receive detailed information regarding the lack of long-term data, particularly on treatments involving the use of BMP.

Juridical implications of the use of bone graft substitutes may occur especially in off-label use and should be avoided, at least if the use of bone grafting is considered as a viable treatment option.