The Use of Montage Bone Putty in Assisting in the Maintenance of Reduction in Comminuted Distal Radius Fractures

Abstract

Background  The distal radius fracture is the most common fracture in the United States. Achieving stable reduction and fixation of complex fracture patterns can be challenging. In order to help maintain reduction of comminuted fracture to simplify plating, the calcium phosphate-based bone putty Montage has been developed.

Questions/Purposes  Does Montage assist in achieving stable reduction and fixation of complex distal radius fractures with an acceptable complication profile?

Patient and Methods  We retrospectively analyzed all patients who were treated intraoperatively with Montage bone putty along with volar plate fixation at a large-volume urban county hospital. Preoperative, intraoperative, and postoperative measurements of radiographic features were recorded at 2 and 6 months, as were any complications. Statistical analysis was then performed on these values.

Results  Preoperative and postoperative radiographs demonstrated significant improvement in standard distal radius fracture measurements, reflecting adequate reduction with the use of Montage intraoperatively. Critically, radiographs demonstrated maintenance of reduction compared to intraoperative fluoroscopy images at 2 months, showing short-term stability of the use of Montage in these fracture patterns as well as long-term stability at 6 months in a subset of patients. There were no major complications in this study.

Conclusion  In this study, we demonstrate the utility of Montage bone putty for complex distal radius fractures with short-term follow-up and limited long-term follow-up. This initial study underlines its efficacy in maintaining reduction without major complications.

Level of Evidence  IV, Therapeutic

Distal radius fractures (DRF) are among the most common fractures in the United States, by some reports comprising up to one-sixth of all fractures. ^{1 2} Despite advanced diagnostic techniques and novel plating systems, achieving appropriate reduction and stability in complex comminuted DRF remains difficult, with increased challenges both intraoperatively and in the postoperative period. Serious sequelae such as arthritis, tendon rupture, and need for reoperation can be correlated with more complex fractures. ^{3 4 5}

As a result, much effort has been made to address poor outcomes after DRF repair, both intraoperatively and postoperatively. ^{6 7 8 9} Intraoperative approaches include the use of many previously used bone substitutes, including allograft and autografts as well as biologic substitutes like demineralized bone matrix and bone morphogenic protein and polymers based on hydroxyapatite and calcium phosphate. ¹⁰ Although these have been previously demonstrated to have success in promoting a stable union after DRF, they each have their own drawbacks, namely, a sole method of bone growth or donor site morbidity.

Recently, the Montage (Abyrx, inc; herein referred to as Montage) hemostatic, absorbable bone putty has come on the market. Made of a hydroxyapatite and tricalcium phosphate-based polymer, Montage, via a normothermic reaction, has been demonstrated to promote bony union via both osteoconductive and osteoinductive methods to allow for peripheral ingrowth of new bone as it expands during hardening to form pores and a path for bone ingrowth without the risks of an exothermic reaction damaging surrounding tissue. ^{11 12 13 14} Further, Montage hardens quickly so screws can be placed through it during the same operation as it is placed. Montage also fully reabsorbs after remodeling of the calcium phosphate, allowing for bony union.

Although Montage has been demonstrated with great success in mouse models and has been explored in craniofacial surgery, especially for mandibular nonunion, as well as spinal and cardiothoracic surgery, ^{15 16} there is a paucity of information on the application of this substance to hand surgery. Therefore, we sought to retrospectively review our patients at a large, urban county hospital who had Montage used for assistance in fracture reduction. Fractures in this population are often complicated by delayed presentation and comminution, as well as inconsistent follow-up and adherence to therapy guidelines. Therefore, having a tool such as Montage to assist in achieving and maintaining reduction would be invaluable.

The aim of this study was to demonstrate that Montage is a safe, easy-to-use adjunct to treating complex, comminuted DRF by assisting in the maintenance of reduction in the short and long term without complications, suggesting its application in a poorly compliant population.

Methods

This study was approved by our Institutional Review Board (IRB# 1470911-2).

Patient Selection and Demographic Data

A retrospective review of all patients from 2017 to 2020 with DRF treated with Montage was performed. Patients were identified based on operative notes, which mentioned use of the material. Use of Montage was a clinical decision made by the senior surgeon based on intraoperative fracture pattern and degree of comminution preventing simple volar fixation. Demographic data, including age, diabetes, American Society of Anesthesiologists (ASA) class, body mass index (BMI), mechanism of injury, handedness, smoking status, and gender, were collected. Time from injury to surgery varied from within 1 week to up to 6 weeks. All surgeries were done without the need for corrective osteotomy; as described previously by our group, we routinely perform reduction and fixation in patients who present in a delayed fashion to great success. ¹⁷

Surgical Technique

Surgery was performed by a fellowship-trained and certified hand surgeon in all cases (level 5 expertise). ¹⁸ Surgeries were performed under tourniquet with a volar or dorsal approach based on the fracture pattern and surgeon preference. Intraoperative maneuvers to improve reduction, such as radial pronation (Orbay), callous takedown, or osteotomies, were also performed under fluoroscopic guidance to assist in reduction. Thereafter, the decision was made to use Montage based on the difficulty and instability of reduction. To use Montage, the container is opened and the two chambers are mixed together for 45 seconds. The unified putty is then placed in the fracture in a similar fashion as bone wax. The Montage hardens after only a few minutes. Thereafter, screws and plates per surgeon preference are placed into the Montage–bone construct—the quick hardening of Montage allows it to accept fixation devices much like normal bone. Muscle and skin were closed primarily and a short volar wrist splint was applied.

Data Collection

Surgical data, including time from injury to surgery, surgical Current Procedural Terminology (CPT) codes, tourniquet time, and surgical approach, were collected from operative notes. Preoperative, intraoperative, and postoperative imaging was analyzed using PACS software to determine the volar tilt, radial inclination, radial height, and presence of articular step-offs by the senior author.

Along with postoperative imaging as described earlier, any postoperative complications were noted, including dehiscence, surgical site infection, and presence of osteolysis or malunion. Postoperative results were recorded using the most recent postoperative visit available.

Statistical Analysis

A paired sample t -test was performed when appropriate to assess changes in preoperative and postoperative imaging using IBM SPSS (Armonk, NY).

Results

Demographic and Surgical Data

A total of 28 patients were included in this study, with an average age of 49.5 years (ranging from 27 to 80 years). This represents 8% of the total 334 surgeries performed for DRF at our institution in this period. Seventeen (61%) were males. Half the patients were nonsmokers, 6 (21%) were former smokers, and 8 (29%) were current smokers. Two patients (7%) had diabetes. All patients were right hand dominant with 16 (57%) having right wrist fractures. Twenty-three patients (82%) suffered their fracture from a fall on their outstretched hand. Per the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification, 8 patients (29%) had type A fractures, 8 (29%) had type B, and 12 (43%) had type C fractures. All fractures were of the comminuted subtypes of these classes.

Surgery was done approximately 21 days after the initial fracture (range: 7–45 days). Eighteen patients (64%) had a volar approach, with the rest having a dorsal approach. The average tourniquet time was 81.3 minutes (range: 45–120 minutes), approximately twice as much as our institution's normal tourniquet time for a DRF, reflecting fracture complexity. Montage took 8 minutes to harden on average. Surgical and demographic data are summarized in Table 1 .

Table 1. Demographic and surgical data.

Age (y)	49.5 (12.7; range: 27–80)
Gender	Male: 61% ( n  = 17) Female: 39% ( n  = 11)
BMI	27.4 (4.1; range: 19.85–36.27)
Smoking status	Nonsmoker: 50% ( n =  14) Current smoker: 29% ( n =  8) Former smoker: 21% ( n =  6)
Diabetes	Yes: 7% ( n =  2) No: 93% ( n =  26)
Patient handedness	Right 100% ( n =  28 Left: 0% ( n =  0)
Fracture laterality	Right: 57% ( n =  16) Left: 43% ( n =  12)
ASA status	ASA 1: 4% ( n =  1) ASA 2: 75% ( n =  21) ASA 3: 21% ( n =  6)
Mechanism of injury	FOOSH: 82% ( n =  23) MVC: 11% ( n =  3) Other: 7% ( n =  2)
Fracture pattern (AO)	Type A: 8 Type B: 8 Type C: 12

Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; FOOSH, fall on outstretched hands; MVC, motor vehicle collision.

The decision to use Montage for these patients was a clinical decision made by the attending surgeon intraoperatively due to the complexity of the fracture and difficulty with achieving stable reduction intraoperatively and not due to any specific preoperative feature of the fracture or patient.

Radiographic Findings

Preoperative and postoperative radiographic measurements were taken of the radial height, ulnar variance, radial inclination, and volar tilt. Postoperative imaging was based on the last image in our system, at a mean of 57 days postoperatively (range: 12–238 days). Intraoperative fluoroscopy was analyzed for radial inclination and volar tilt, as our PACS software could not measure the intraoperative radial height and ulnar variance due to lack of scale.

Preoperative radial height was found to be an average of 8.68 ± 3.24 mm and postoperatively 11.07 ± 2.99 mm ( p  = 0.001). The preoperative ulnar variance was –0.66 ± 2.82 mm, while the postoperative measurements were –1.50 ± 2.48 mm ( p  = 0.052). There was significant qualitative improvement of these measurements on fluoroscopy after intraoperative fixation, with excellent qualitative congruence with postoperative films. The preoperative radial inclination was found to be 16.04 ± 4.97 degrees, while the postoperative radial inclination was 17.93 ± 4.33 degrees ( p  = 0.184).

Notably, intraoperative radial inclination was 18.36 ± 4.44 degrees, not different from the postoperative data. The preoperative volar tilt was measured at –11.82 ± 11.31 degrees and the postoperative volar tilt was at 4.18 ± 6.30 degrees ( p  = 0.000). The intraoperative volar tilt was 3.46 ± 6.32 degrees, statistically equivalent to the postoperative value. All intraarticular step-offs found preoperatively resolved postoperatively. These data are summarized in Table 2 . Representative images of pre-, intra-, and postoperative fracture appearance are shown in Figs. 1 and 2 .

Table 2. Radiographic data.

	Preoperative	Intraoperative	Postoperative a	p -value (pre- vs. post-op)	p -value (intra- vs. post-op)
Radial height	8.68 mm (3.24)	b	11.07 mm (2.99)	p  = 0.001	b
Ulnar variance	–0.66 mm (2.82)	b	–1.50 mm (2.48)	p  = 0.052	b
Radial inclination	16.04 degrees (4.97)	18.36 degrees (4.44)	17.93 degrees (4.33)	p  = 0.184	p  = 1
Volar tilt	–11.82 degrees (11.31)	3.46 degrees (6.32)	4.18 degrees (6.30)	p  = 0.00	p  = 1

Note: The value in brackets is the standard deviation.

^aPost-op measurement based on most recent films in the system (average 57 days post-op; range: 12–238 days).

^bQualitative review of images demonstrates stability of postoperative reduction compared to intraoperative fluoroscopy.

Fig. 1.

This patient is 48-year-old right hand dominant male construction worker who fell on his outstretched hand off a ladder. He was a nonsmoker and otherwise healthy. He presented for operation 23 days after injury. Intraoperatively, he had a tourniquet time of 120 minutes. He had no postoperative complications with his last follow-up visit and X-ray about 187 days after surgery. ( a ) Preoperative X-rays. ( b ) Intraoperative fluoroscopy images. ( c ) Postoperative X-rays. Note the persistent visualization of Montage and preservation of intraoperative reduction nearly 6 months out from surgery.

Fig. 2.

This patient is a 44-year-old right hand dominant unemployed male who fell on his outstretched hand from a ground level fall. He was a smoker but otherwise healthy. He presented for operation 10 days after injury. Intraoperatively, he had a tourniquet time of 83 minutes. He had no postoperative complications at his last follow-up visit and X-ray 27 days after surgery. ( a ) Preoperative X-rays. ( b ) Intraoperative fluoroscopy images. ( c ) Postoperative X-rays. Montage is slightly obscured by projection of the volar plate, but reduction is stable.

Seven patients of this dataset had follow-up X-rays at least 6 months from injury, ranging from 6 months to 2 years. In these patients, maintenance of reduction with full bony healing is evident. Additionally, the Montage has completely been replaced with bone and is no longer evident on the X-ray as it is immediately postoperatively ( Fig. 3 ).

Fig. 3.

This patient is a 47-year-old right hand dominant male who fell on his outstretched hand. He presented for operation 12 days after injury. As demonstrated from left to right, the preoperative image shows a complex distal radius fracture with adequate reduction with evident radiodensity corresponding to Montage in the middle image. Reduction is maintained at 1 year postoperatively with healing of the fracture line and reabsorption of the Montage, as evident by the uniform appearance of the bone.

Postoperative Complications

No postoperative infection, osteolysis, or nonunion was noted. Although one patient had superficial dehiscence of their wound, this was managed with local wound care and did not require return to the operating room. No further complications were noted.

Discussion

In our study, we retrospectively analyzed patients with DRF where we opted to use the Montage bone putty to aid in maintaining fracture reduction during plating. Importantly, use of the bone putty was a clinical decision made based on intraoperative findings. In analyzing outcomes, we found maintenance of reduction in the short term and improvement from preoperative imaging without increased complications. Furthermore, the Montage cohort did not require additional percutaneous Kirschner's wire placement, spanning plates, or external fixation to achieve stable fixation while proving to be an easy-to-use and versatile substance with minimal impact on operative time.

Pre- and postoperative changes in standard measurements reflected the ability to achieve improved alignment after operative intervention. Montage significantly improved our ability to capture and convert small, comminuted fragments into a larger segment to facilitate anatomic reduction. Coupled with its unique characteristic of hardening after a soft puttylike “glue” phase, the Montage-fracture fragment unit was able to be fixed with threaded screws.

Most importantly, there was good preservation of intraoperative fracture reduction on postoperative films, taken at an average of 2 months postoperatively. Both radial inclination and volar tilt were statistically equivalent at the postoperative visit. Quantitative comparison of intraoperative and postoperative data is limited due to intraoperative scaling, but qualitative assessment showed preservation of intraoperative radial height, ulnar variance, and reduction, as well as radial inclination and volar tilt postoperatively with use of Montage. This suggests that Montage can be useful for complex fractures to assist with maintenance of reduction in the short term. Further, we did not have any postoperative infections in our cohort, suggesting that Montage is not associated with increased surgical site infection.

Long-term outcomes were limited; however, several patients did have follow-up imaging of at least 6 months after intervention that again showed maintenance of reduction. Additionally, the area of Montage seen on the immediate postoperative film was replaced with bone radiographically indistinguishable from the native bone, suggesting that the putty is fully replaced by native tissue. This long-term benefit allows for a financial benefit as well, reducing the need for reoperation and further treatment for these patients.

Montage is introduced as a soft, malleable substance that allows it to fill small crevices and large defects. Once it hardens, it can retain its shape and integrity to accommodate drilling and placement of screws within the putty. During the setting process, the material remains at below normal body temperature, eliminating concerns with traditional bone cement, which often produces an exothermic reaction. During the postoperative period, it has both osteoinductive and osteoconductive properties, as its porous nature allows for ingrowth of bone. While Montage is ultimately resorbable, the material lasts until the calcium phosphate scaffold is remodeled into bone, promoting bony union. Again, this resorption is evident at 6 months postoperatively.

Further, Montage obviates the need for external fixation although use of such techniques are typically required given the fracture pattern. Its quick hardening allows for screw placement within the material, again an advancement over other materials, and its osteoinductive properties augment the bony integration of the space. Importantly, studies of previous materials are all over a decade old. Montage represents a new technology in DRF. As with any new technology, there is risk with complications, but our data set does not demonstrate any infection that can be linked to use of Montage, as only one patient had a superficial dehiscence, which was managed conservatively and ultimately healed without additional sequelae.

Montage provides advantages over other bony substitutes, such as the Norian bone paste, in several areas. Although there is a paucity of recent studies on the use of bony substitutes in DRF, several older studies have described a hydroxyapatite-based material along with a combination of external and internal fixation. ^{19 20} However, these materials only allow for osteoconduction, not osteoinduction, and require external Kirschner's wire fixation to promote articular surface reduction and stability, providing further discomfort for the patient. Without external fixation, the hydroxyapatite material underwent resorption and loss of reduction over time. Similarly allogenic bone graft, bone chips, and demineralized bone matrix only allow for osteoconduction, ^{21 22 23 24 25 26} whereas mouse model studies demonstrate that Montage provides both osteoconduction and osteoinduction, allowing for more reliable bone growth and replacement of the substance. Although autologous bone grafting can provide osteogenesis, osteoconduction, and osteoinduction, it requires a secondary operative site with the associated risks of more extensive surgery. ²⁷ Montage also has “gluelike” properties that other bone substitutes do not, which allows us to capture and fixate small osseous fragments that would be missed by traditional fixation methods. Montage is compatible with internal volar and dorsal plating systems, making it broadly applicable, especially in underserved areas, making it a useful option for complex fractures worldwide.

Although we believe this study has many strengths, there are certain limitations. Importantly, we have a retrospective series of 28 patients only. This cohort size may exhibit variations due to sampling, introducing error into the analysis. A retrospective review also implies limited data obtained at each visit. Likewise, long-term follow-up is only available in seven patients, which is an unfortunate reflection of this hospital setting and patient population in which this study was performed. Functional data were similarly limited because of poor patient follow-up. Thus, the persistent benefit of Montage cannot be studied with robust statistical certainty despite encouraging outcomes in this cohort. Future areas of study include larger cohorts and follow-up of these patients multiple years after surgery.

DRF remain a significant cause of orthopaedic injuries. Although most fractures can be treated with straightforward plating, more complex fractures may require additional support. In this study, we demonstrate that Montage bone putty is an effective option to promote good bony union and fracture reduction stability in the short term and has long-term maintenance of reduction with replacement with native bone. Given the promising outcomes in this study, we believe that Montage is a useful adjunct in the hand surgery toolbox that merits use and further study.

Funding Statement

Funding None.