ORIGINAL ARTICLE
Dynamizations and Exchanges: Success Rates and Indications Jody Litrenta, MD,* Paul Tornetta III, MD,* Heather Vallier, MD,† Reza Firoozabadi, MD,‡ Ross Leighton, MD,§ Kenneth Egol, MD,k Christiane Kruppa, MD,¶ Clifford B. Jones, MD,¶ Cory Collinge, MD,** Mohit Bhandari, MD,†† Emil Schemitsch, MD,‡‡ David Sanders, MD,§§ and Brian Mullis, MDkk
Objective: To characterize the timing, indications, and “success rates of secondary interventions, dynamization and exchange nailing, in a large series of tibial nonunions” (dynamization and exchange nailing are types of secondary interventions).
Setting: Retrospective multicenter analysis from level 1 trauma hospitals.
Patients: A total of 194 tibia fractures that underwent dynamization or exchange nailing for delayed/nonunion. Intervention: Records and radiographs to characterize demographic data, fracture type, and cortical contact after tibial nailing were gathered. The radiographic union score for tibias (RUST) and the timing of intervention and time to union were calculated. Main Outcome Measures: The primary outcome was success of either intervention, defined as achieving union, with the need for further intervention defining failure. Other outcomes included RUST scores at intervention and union, and timing to intervention and union for both techniques. Two-tailed t tests and Fisher exact with P set at ,0.05 for significance were used as indicated. Results: A total of 194 tibia fractures underwent dynamization (97) or exchange nailing (97). No statistical differences were found between groups with demographic characteristics. The presence of a fracture gap (P = 0.01) and comminuted fractures (P = 0.002) was more common in the exchange group. The success rates of the Accepted for publication February 4, 2015. From the *Boston Medical Center, Boston, MA; †MetroHealth Medical Center, Cleveland, OH; ‡Harborview Medical Center, Seattle, WA; §Dalhousie University, Halifax, Nova Scotia, Canada; kNYU Hospital for Joint Diseases; ¶Orthopaedic Associates of Michigan, Grand Rapids, MI; **Orthopedic Specialty Associates, Fort Worth, TX; ††McMaster University, Hamilton, Ontario, Canada; ‡‡St-Michael’s University of Toronto, Toronto, Canada; §§London Health Sciences Centre, London, Ontario, Canada; and kkIndiana University, Indianapolis, IN. Presented in part at the Annual Meeting of the Orthopaedic Trauma Association, October 2013, Phoenix, AZ, the American Academy of Orthopaedic Surgeons Annual Meeting, March 2014, New Orleans, LA, and as a poster presentation at the American Orthopaedic Association June 2014, Montreal, Canada. The authors report no conflict of interest. IRB approval was obtained for this study with DUA agreements from all centers. Reprints: Paul Tornetta III, MD, 850 Harrison Avenue, Dowling 2 North, Boston Medical Center, Boston, MA 02118 (e-mail: [email protected]). Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Orthop Trauma Volume 29, Number 12, December 2015
interventions and RUST scores were not different when performed before versus after 6 months; therefore, data were pooled. The RUST scores at the time of intervention were not different for successful or failed dynamizations (7.13 vs. 7.07, P = 0.83) or exchanges (6.8 vs. 7.3, P = 0.37). Likewise, the time to successful versus failed dynamization (165 vs. 158 days, P = 0.91) or exchange nailing (224 vs. 201 days, P = 0.48) was not different. No cortical contact or a gap was a statistically negative factor for both exchange nails (P = 0.09) and dynamizations (P = 0.06). When combined, the success in the face of a gap was 78% versus 92% when no gap was present (P = 0.02).
Conclusions: Previous literature has few reports of the success rates of secondary interventions for tibial nonunions. The indications for dynamization and exchange were similar. Comminuted fractures, and fractures with no cortical contact or “gap” present after intramedullary nailing, favored having an exchange nail performed over dynamization. Fracture gap was also found to be a negative prognostic factor for both procedures. Overall, this study demonstrates high rates of union for both interventions, making them both viable options. Key Words: dynamization, exchange nail, tibial nonunion, tibial delayed union
Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. (J Orthop Trauma 2015;29:569–573)
INTRODUCTION Nonunion and delayed union of tibia fractures remains a prevalent complication that can be difficult to manage. The rate of nonunion reported after intramedullary nailing varies, affecting approximately 5%–17% of closed and as many as 40% of open tibial shaft fractures.1,2,6–8 Some of this variation can be attributed to differences in fracture morphology,3 soft tissue quality, and surgical techniques.4,5,9–13 Secondary interventions, including dynamization and exchange nailing, are 2 commonly used operative techniques to promote healing in tibial delayed union or nonunion. Dynamization involves the removal of the proximal or distal statically locked screws from an intramedullary nail to promote healing by collapsing any relevant gaps (Fig. 1).14 In theory, this technique takes advantage of the biologic benefit of stress at the fracture; however, there are very limited www.jorthotrauma.com |
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Litrenta et al
J Orthop Trauma Volume 29, Number 12, December 2015
FIGURE 1. Example of the preop (A) and postop (B) radiographs of a 24year-old male patient who had a grade IIIC open tibia fracture. At 161 days postop, he was treated with dynamization by removal of the distal screws for a RUST score of 5 (C); at 334 days postop, he was considered healed with a RUST score of 10 (D).
data to support its use. Wu and Shih16 demonstrated a 54% success rate in a small study that included only 11 patients with tibial nonunions. In another series of 125 tibial shaft fractures, 32 patients were treated with removal of the interlocking screws for the purpose of either dynamization or removal of symptomatic implants.17 It was the authors’ impression that this procedure did not affect union rates; however, these groups were not matched and the timing of intervention and success rates were not reported. Exchange nailing involves removal of the tibial nail, reaming, and replacement with a larger diameter nail. This technique takes advantage of the biologic properties of reaming and additional mechanical stability conferred from a larger diameter nail for progression of healing. Exchange nailing has greater reported success rate in the literature, but all in small series.18–20 A review of 6 studies documented success rate of 76%–96% for noncomminuted diaphyseal tibia fractures.21 Presently, the largest series of exchange nailing in tibial nonunions included 33 patients with a success rate of 73%. Both dynamization and exchange nailing lack data from a large series of tibial nonunions. Despite this, both remain an extremely commonly used technique in the treatment of delayed and nonunion of the tibia. Therefore, the purpose of this study is to report the indications and success rates of these 2 techniques in a large series of patients. Additionally, we aim to identify the factors that may contribute to the success or failure of either technique. We also seek to further
characterize these techniques by radiographically quantifying the amount of healing present at intervention and at union for each technique.
570
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METHODS Retrospective data from chart review and radiographs were reviewed from 194 tibias from 25 trauma centers in the United States and Canada, of which 24 were level 1. This included 8 institutions that retrospectively reviewed patients and prospectively gathered data in the SPRINT database from an additional 17 sites. All skeletally mature patients treated initially with intramedullary nailing for a tibia fracture who underwent a secondary intervention for delayed or nonunion were included. We also inquired about the use of any adjunct procedure performed at secondary intervention, such as fibulectomy. Infected nonunions and interventions other than dynamization or exchange nailing were excluded. Patients with significant bone loss treated initially with bone graft or spacers were also excluded, as were those treated with open grafting at the time of secondary intervention.
Chart Review The screening of patients varied by institution. At our home institution, patients were identified from billing records using current procedural terminology codes. Other sites used the same method or used previously established nonunion
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J Orthop Trauma Volume 29, Number 12, December 2015
databases. Additionally, the SPRINT database was screened to identify a subset of patients who underwent dynamization or exchange nailing. In the SPRINT trial, secondary procedures to gain union were disallowed for the first 6 months unless there was a fracture gap greater than 1 cm present after the index intramedullary nailing.15 Detailed reoperation data are available for these patients, and we were able to review these records of reoperation and identify patients meeting our inclusion criteria. All charts were reviewed for the following relevant data regarding demographics, injury, and fixations characteristics, and type and timing of interventions: 1. Demographics: Age, gender, smoking history, and presence of diabetes. 2. Injury characteristics: Mechanism of injury, fracture location, fracture pattern, and open or closed with associated Gustilo grade. 3. Fixation characteristics: Date of fixation, reamed versus unreamed nailing, and fracture gap, defined as a minimum 5 mm distraction in an area of no cortical contact. 4. Secondary interventions: Date and type of procedure (dynamization and exchange nailing).
Radiographic Evaluation The radiographic union score of tibias (RUST)22 was used to quantify healing at the time of index intervention and at the final follow-up. The RUST score is calculated from AP and lateral radiographs. Each cortex is given a score of 1 = no healing, 2 = callus present or bridging, or 3 = remodeled. These scores are summed for a total of 4–12. It is a previously validated score in the evaluation of tibial shaft fractures treated by intramedullary nailing.22,23 Success was defined per discretion of the attending surgeon, considering both radiographic and clinical presentation. Failure was defined as either the need for additional surgical intervention or lack of healing after secondary intervention.
Statistics Two-tailed t tests were performed to compare timing to intervention, time to union, RUST scores at intervention, RUST scores at union between tibia fractures treated with dynamization versus those treated with exchange nailing. Comparisons between categorical variables were performed with Fisher exact or x2 analysis where appropriate. These analyses were used to determine whether certain fracture characteristics influenced the indications or success of either secondary intervention.
Dynamizations and Exchanges
TABLE 1. Demographic Data Dynamizations (97) Age Range 18–82 Mean 39 Gender Female 29 Male 68 Smoking (179) Current/past 47 Nonsmokers 43 Diabetes (189) No 90 Yes (total) 6 IDDM 1 Mechanism (190) MVC 22 MCC 25 Pedestrian struck 16 Fall 19 Direct blow 9 Sports injury 2 GSW 2 Location (193) Metadiaphyseal 63 Diaphyseal 34 Fracture pattern (191) Oblique 31 Segmental 13 Transverse 24 Comminuted 29 Open vs. closed (194) Closed 34 Open 63 I 13 II 17 III (all) 27 IIIA 15 IIIB/C 11 Reamed vs. unreamed (188) Reamed 66 Unreamed 27 Presence of fracture gap (183) Present ($5 mm) 19 No gap 74
Exchanges (97)
P NS
16–72 39 0.04 16 81 NS 37 52 NS 84 9 3 NS 34 23 16 9 8 4 1 NS 60 36 0.002 20 8 12 54
* NS
41 56 6 16 31 21 10 NS 78 17 34 56
0.01 *
*More comminuted fractures and those with a gap receive exchange nail. NS, not significant.
RESULTS A total of 194 tibia fractures underwent dynamization (97) or exchange nailing (97) performed between 2001 and 2012. All interventions were performed in isolation and did not include the addition of fibulectomy or any other procedure. The average age was 39 years (16–81), and there were 149 men and 45 women. Mechanisms of injury were mitral valve area (56), MCA (48), pedestrian struck (32), falls (28), direct blow (17), and other (13). There were 119 open (49% grade III) and 75 closed fractures in the proximal (14%), Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
midshaft (39%), or distal (50%) tibia, including isolated and segmental fractures. Complete data regarding union were available for 179 tibias with 15 lost to follow-up.
Categorical Variables Analysis of demographic variables between patients undergoing dynamization versus exchange nailing is seen in Table 1. Results are based on the most complete data from our www.jorthotrauma.com |
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Litrenta et al
TABLE 2. Factors Affecting Success of Secondary Interventions Dynamization
N = 88
Exchange Nailing
N = 91
Success vs. open/closed fracture Success vs. fracture location Success vs. fracture pattern Success vs. fracture gap Dynamization vs. fracture gap Exchange nailing vs. fracture gap
P P P P P P
= = = = = =
1.00 0.37 0.07 0.02 0.06 0.09
series of 194 tibias; the exact number of complete data available for each variable is recorded here. We found that male patients were more likely to undergo exchange nailing than dynamization (P = 0.04); however, no other demographic variables significantly differed between the 2 groups. Also, there was no difference in the likelihood of undergoing exchange nailing or dynamization based on location (metaphyseal vs. diaphyseal fractures, P = 0.88) or open versus closed fractures (P = 0.29). However, regarding fracture pattern, comminuted fractures were more likely to undergo exchange nailing (P = 0.002). Additionally, fractures with a gap, identified after initial intramedullary nailing, were more likely to undergo exchange nailing than dynamization (P = 0.01). It is important to note that there was an association between comminuted fractures and those with a gap. In our series, 60% of fractures with a gap were characterized as comminuted compared with 38% without a gap. No other fracture pattern was associated with a fracture gap. The success or failure of either intervention was not different based on fracture location (metaphyseal vs. diaphyseal), open versus closed fractures, or fracture pattern. The presence of a fracture gap was a significantly negative predictor of success for all secondary interventions (78% vs. 92%, P = 0.02). In comparison of successful versus failed dynamizations, the presence of a gap was proportionately higher in failed dynamizations (P = 0.06). Similarly, the presence of a gap was more common although not statistically significant in failed exchange nailings (P = 0.09) (Table 2).
Continuous Variables Because the SPRINT study arbitrarily used 6 months as a cutoff for secondary intervention, we evaluated that time point as a potential factor in the success of interventions. The RUST scores at the time of intervention and the success rates of the interventions were not different for exchange nails (P = 0.43 and 0.3, respectively) or dynamizations (P = 0.96 and 0.75, respectively) performed before 6 months versus after 6 months,
allowing for pooling of the data. Fifteen patients were lost to follow-up leaving 179 fractures followed to union or failure. The median time to intervention was 157 days for dynamization and 192 days for exchange nailing. Union was achieved in 83% of dynamizations and 90% of exchange nails (P = 0.19) at a median time of 334 and 407 days after index procedure, respectively. RUST scores at the time of intervention were 7.1 for dynamization and 6.8 for exchange nails (P = 0.09, Table 3). RUST scores were also not different for successful or failed dynamizations (7.13 vs. 7.07, P = 0.83) or exchanges (6.8 vs. 7.3, P = 0.37). Likewise, the time to successful versus failed dynamization (165 vs. 158 days, P = 0.91) or exchange nailing (224 vs. 201 days, P = 0.48) was not different (Table 3). This represents less than 1 grade on 1 cortex difference in scoring.
DISCUSSION Tibial nonunion significantly impacts recovery and the ability to heal these fractures with the appropriate intervention is obviously desirable. There is little previous research to support dynamization. A small series by Wu and Shih16 demonstrated a success rate of 54% in 11 tibial nonunions treated 4–12 months after nailing. Although dynamization is a frequently used technique, there are no other larger series to support its use. Exchange nailing has gained more support in the literature, with success rates of 72%–96%.18–20 However, the largest of these series involved 33 patients with a success rate of 73%. Among those that failed, 55% had bone loss that required grafting and another 33% had distraction at the fracture site after the index nailing.18 Both Templeman and Court-Brown reported that bone loss had a negative effect on exchange nailing.18,19 No previous study has determined if other fracture characteristics may influence the surgeon’s preference or successful outcome of either technique. This study is the first large retrospective study regarding outcomes of dynamizations and exchange nailing. Overall, we found a high success rate for both interventions across a variety of fracture types and locations. In our analysis, we found that neither the location of the fracture nor whether the fracture was open versus closed influenced the choice of dynamization or exchange nailing across a large cross section. More importantly, we observed that these interventions are similar in terms of their success rates, supporting both procedures. One of our study goals was to determine the present indications for either procedure. We found that age, smoking status, diabetes, fracture location, and open or closed fractures did not affect surgeon’s choice of intervention. However, we did demonstrate that gender, comminution, and fracture gap
TABLE 3. Outcomes of Secondary Interventions Intervention
N
Median Days to Surgery (days)
RUST Preop
Union, n (%)
Median Time to Union (mo)
RUST Union
Dynamization Exchange P
88 91 NA
157 192 NA
7.1 6.8 0.09
73 (83) 82 (90) 0.19
11.1 13.4 NA
10.2 10.4 0.5
NA, not available.
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J Orthop Trauma Volume 29, Number 12, December 2015
may be a significant factor in the choice between interventions. Male patients, comminuted fractures, and those with a gap were more likely to undergo exchange nailing. These factors are somewhat related, as associated comminution represents a relatively higher percentage of fractures with a gap compared with those without a gap. We also sought to determine the factors associated with success of either procedure. Fracture location, open versus closed fractures, and fracture pattern did not affect the outcome. The only factor identified as significant was the presence of a fracture gap. Overall, the success in the face of a gap was 78% compared with 92% when no gap was present. The presence of a gap has previously been identified as a problem. In the SPRINT study, fractures that had no cortical contact (ie, an iatrogenic gap) were allowed to be dynamized to correct this technical error.15 Other studies demonstrated that among tibia fractures that failed exchange nailing, the primary reason was a need for bone graft secondary to bone loss.18,19 Our study defined a fracture gap as $5 mm of complete cortical discontinuity. We were not able to further characterize the gap precisely, as radiographic evaluation was limited after nailing, and these data were not available in all cases from operative reports. Further evaluation of the fracture gap is therefore needed to help surgeons identify fractures that may be better suited for exchange nailing. Furthermore, this is the first study to quantify radiographic parameters both at the time of intervention and at union. Previous work has demonstrated good inter- and intraobserver reliability of the RUST score but did not correlate scores with a clinical evidence of union.22,23 Our study demonstrated an average RUST score of 6.9 at the time of intervention for both dynamization and exchange and a RUST of 10.3 at the time of union. Clinically, a RUST score of 7 correlates with callus present on three-fourth of the cortices and a RUST of 10 indicates at least 2 remodeled cortices. Therefore, this suggests that orthopaedic surgeons intervene in the absence of any remodeled cortices or when two-fourth of the cortices demonstrate a lack of healing. A RUST score of 10 at union indicates that these healed fractures are remodeled on at least 2 cortices. Additionally, we found that RUST scores at the time of intervention were not predictive of success of either intervention. In summary, we found high rates of success for both dynamization and exchange nailing. Both techniques seem to have a role in the treatment of tibial nonunion. This conclusion is strengthened by the similarity in the timing of the interventions and the RUST scores at the index procedure. However, we did identify that comminuted fractures and those with a gap are more often treated with an exchange nail procedure. The only predictor of success was the presence of a fracture gap, and further work is needed to determine how various gaps and defects should be managed.
ACKNOWLEDGMENTS The authors thank Dr. Juan de Dios Robinson for his contributions of data collection and presentation of this research.
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Dynamizations and Exchanges
REFERENCES 1. Goulet JA, Templeman D. Delayed and nonunion of the tibial shaft. Instr Course Lect. 1997;46:281–291. 2. Hak DJ. Management of aspetic tibial nonunion. J Am Acad Orthop Surg. 2011;19:563–573. 3. Johner R, Wruhs O. Classification of tibial shaft fractures and correlation with results after rigid internal fixation. Clin Orthop Relat Res. 1983;178: 7–25. 4. Coles CP, Gross M. Closed tibial shaft fractures: management and treatment complications. A review of the prospective literature. Can J Surg. 2000;43:256–262. 5. Forster MC, Bruce AS, Aster AS. Should the tibia be reamed when nailing? Injury. 2005;36:439–444. 6. Hooper GJ, Keddell RG, Penny ID. Conservative management or closed nailing for tibial shaft fractures. A randomised prospective trial. J Bone Joint Surg Br. 1991;73:83–85. 7. Gregory P, Sanders R. The treatment of closed, unstable tibial shaft fractures with unreamed interlocking nails. Clin Orthop Relat Res. 1995;315:48–55. 8. Court-Brown CM, Will E, Christie J, et al. Reamed or unreamed nailing for closed tibial fractures. A prospective study in Tscherne C1 fractures. J Bone Joint Surg Br. 1996:78;580–583. 9. Bone LB, Sucato D, Stegemann PM, et al. Displaced isolated fractures of the tibial shaft treated with either a cast or intramedullary nailing. An outcome analysis of matched pairs of patients. J Bone Joint Surg Am. 1997:79;1336–1341. 10. Clancey GJ, Hansen ST Jr. Open fractures of the tibia: a review of one hundred and two cases. J Bone Joint Surg Am. 1978:60; 118–122. 11. Sanders R, Jersinovich I, Anglen J, et al. The treatment of open tibial shaft fractures using an interlocked intramedullary nail without reaming. J Orthop Trauma. 1994:8;504–510. 12. Keating JF, O’Brien PJ, Blachut PA, et al. Reamed interlocking intramedullary nailing of open fractures of the tibia. Clin Orthop Relat Res. 1997;338:182–191. 13. Keating JF, O’Brien PJ, Blachut PA, et al. Locking intramedullary nailing with and without reaming for open fractures of the tibial shaft. A prospective, randomized study. J Bone Joint Surg Am. 1997:79; 334–341. 14. Kakar S, Tornetta P III. Open fractures of the tibia treated by immediate intramedullary tibial nail insertion without reaming: a prospective study. J Orthop Trauma. 2007:21;153–157. 15. SPRINT Investigators. Randomized Trial of Reamed and unreamed intramedullary nailing of tibial shaft fractures. J Bone Joint Surg Am. 2008: 90;2567–2578. 16. Wu CC, Shih CH. Effect of dynamization of a static interlocking nail on fracture healing. Can J Surg. 1993:36;302–306. 17. Court-Brown CM, Christie J, McQueen MM. Closed intramedullary tibial nailing. Its use in closed and type I open fractures. J Bone Joint Surg Br. 1990:72;605–611. 18. Court-Brown CM, Keating JF, Christie J, et al. Exchange intramedullary nailing. Its use in aseptic tibial nonunion. J Bone Joint Surg Br. 1995:77; 407–411. 19. Templeman D, Thomas M, Varecka T, et al. Exchange reamed intramedullary nailing for delayed union and nonunion of the tibia. Clin Orthop Relat Res. 1995;315:169–175. 20. Wu CC, Shih CH, Chen WJ, et al. High success rate with exchange nailing to treat tibial shaft aseptic nonunion. J Orthop Trauma. 1999: 13;33–38. 21. Brinker MR, O’Connor DP. Exchange nailing of ununited fractures. J Bone Joint Surg Am. 2007:89;177–188. 22. Whelan DB, Bhandari M, Stephen D, et al. Development of the radiographic union score for tibial fractures for the assessment of tibial fracture healing after intramedullary fixation. J Trauma. 2010: 68;629–632. 23. Kooistra BW, Dijkman BG, Busse JW, et al. The radiographic union scale in tibial fractures: reliability and validity. J Orthop Trauma. 2010; 24(suppl 1):S81–S86.
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Dynamizations and Exchanges: Success Rates and Indications Jody Litrenta, MD,* Paul Tornetta III, MD,* Heather Vallier, MD,† Reza Firoozabadi, MD,‡ Ross Leighton, MD,§ Kenneth Egol, MD,k Christiane Kruppa, MD,¶ Clifford B. Jones, MD,¶ Cory Collinge, MD,** Mohit Bhandari, MD,†† Emil Schemitsch, MD,‡‡ David Sanders, MD,§§ and Brian Mullis, MDkk
Objective: To characterize the timing, indications, and “success rates of secondary interventions, dynamization and exchange nailing, in a large series of tibial nonunions” (dynamization and exchange nailing are types of secondary interventions).
Setting: Retrospective multicenter analysis from level 1 trauma hospitals.
Patients: A total of 194 tibia fractures that underwent dynamization or exchange nailing for delayed/nonunion. Intervention: Records and radiographs to characterize demographic data, fracture type, and cortical contact after tibial nailing were gathered. The radiographic union score for tibias (RUST) and the timing of intervention and time to union were calculated. Main Outcome Measures: The primary outcome was success of either intervention, defined as achieving union, with the need for further intervention defining failure. Other outcomes included RUST scores at intervention and union, and timing to intervention and union for both techniques. Two-tailed t tests and Fisher exact with P set at ,0.05 for significance were used as indicated. Results: A total of 194 tibia fractures underwent dynamization (97) or exchange nailing (97). No statistical differences were found between groups with demographic characteristics. The presence of a fracture gap (P = 0.01) and comminuted fractures (P = 0.002) was more common in the exchange group. The success rates of the Accepted for publication February 4, 2015. From the *Boston Medical Center, Boston, MA; †MetroHealth Medical Center, Cleveland, OH; ‡Harborview Medical Center, Seattle, WA; §Dalhousie University, Halifax, Nova Scotia, Canada; kNYU Hospital for Joint Diseases; ¶Orthopaedic Associates of Michigan, Grand Rapids, MI; **Orthopedic Specialty Associates, Fort Worth, TX; ††McMaster University, Hamilton, Ontario, Canada; ‡‡St-Michael’s University of Toronto, Toronto, Canada; §§London Health Sciences Centre, London, Ontario, Canada; and kkIndiana University, Indianapolis, IN. Presented in part at the Annual Meeting of the Orthopaedic Trauma Association, October 2013, Phoenix, AZ, the American Academy of Orthopaedic Surgeons Annual Meeting, March 2014, New Orleans, LA, and as a poster presentation at the American Orthopaedic Association June 2014, Montreal, Canada. The authors report no conflict of interest. IRB approval was obtained for this study with DUA agreements from all centers. Reprints: Paul Tornetta III, MD, 850 Harrison Avenue, Dowling 2 North, Boston Medical Center, Boston, MA 02118 (e-mail: [email protected]). Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Orthop Trauma Volume 29, Number 12, December 2015
interventions and RUST scores were not different when performed before versus after 6 months; therefore, data were pooled. The RUST scores at the time of intervention were not different for successful or failed dynamizations (7.13 vs. 7.07, P = 0.83) or exchanges (6.8 vs. 7.3, P = 0.37). Likewise, the time to successful versus failed dynamization (165 vs. 158 days, P = 0.91) or exchange nailing (224 vs. 201 days, P = 0.48) was not different. No cortical contact or a gap was a statistically negative factor for both exchange nails (P = 0.09) and dynamizations (P = 0.06). When combined, the success in the face of a gap was 78% versus 92% when no gap was present (P = 0.02).
Conclusions: Previous literature has few reports of the success rates of secondary interventions for tibial nonunions. The indications for dynamization and exchange were similar. Comminuted fractures, and fractures with no cortical contact or “gap” present after intramedullary nailing, favored having an exchange nail performed over dynamization. Fracture gap was also found to be a negative prognostic factor for both procedures. Overall, this study demonstrates high rates of union for both interventions, making them both viable options. Key Words: dynamization, exchange nail, tibial nonunion, tibial delayed union
Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. (J Orthop Trauma 2015;29:569–573)
INTRODUCTION Nonunion and delayed union of tibia fractures remains a prevalent complication that can be difficult to manage. The rate of nonunion reported after intramedullary nailing varies, affecting approximately 5%–17% of closed and as many as 40% of open tibial shaft fractures.1,2,6–8 Some of this variation can be attributed to differences in fracture morphology,3 soft tissue quality, and surgical techniques.4,5,9–13 Secondary interventions, including dynamization and exchange nailing, are 2 commonly used operative techniques to promote healing in tibial delayed union or nonunion. Dynamization involves the removal of the proximal or distal statically locked screws from an intramedullary nail to promote healing by collapsing any relevant gaps (Fig. 1).14 In theory, this technique takes advantage of the biologic benefit of stress at the fracture; however, there are very limited www.jorthotrauma.com |
569
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Litrenta et al
J Orthop Trauma Volume 29, Number 12, December 2015
FIGURE 1. Example of the preop (A) and postop (B) radiographs of a 24year-old male patient who had a grade IIIC open tibia fracture. At 161 days postop, he was treated with dynamization by removal of the distal screws for a RUST score of 5 (C); at 334 days postop, he was considered healed with a RUST score of 10 (D).
data to support its use. Wu and Shih16 demonstrated a 54% success rate in a small study that included only 11 patients with tibial nonunions. In another series of 125 tibial shaft fractures, 32 patients were treated with removal of the interlocking screws for the purpose of either dynamization or removal of symptomatic implants.17 It was the authors’ impression that this procedure did not affect union rates; however, these groups were not matched and the timing of intervention and success rates were not reported. Exchange nailing involves removal of the tibial nail, reaming, and replacement with a larger diameter nail. This technique takes advantage of the biologic properties of reaming and additional mechanical stability conferred from a larger diameter nail for progression of healing. Exchange nailing has greater reported success rate in the literature, but all in small series.18–20 A review of 6 studies documented success rate of 76%–96% for noncomminuted diaphyseal tibia fractures.21 Presently, the largest series of exchange nailing in tibial nonunions included 33 patients with a success rate of 73%. Both dynamization and exchange nailing lack data from a large series of tibial nonunions. Despite this, both remain an extremely commonly used technique in the treatment of delayed and nonunion of the tibia. Therefore, the purpose of this study is to report the indications and success rates of these 2 techniques in a large series of patients. Additionally, we aim to identify the factors that may contribute to the success or failure of either technique. We also seek to further
characterize these techniques by radiographically quantifying the amount of healing present at intervention and at union for each technique.
570
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
| www.jorthotrauma.com
METHODS Retrospective data from chart review and radiographs were reviewed from 194 tibias from 25 trauma centers in the United States and Canada, of which 24 were level 1. This included 8 institutions that retrospectively reviewed patients and prospectively gathered data in the SPRINT database from an additional 17 sites. All skeletally mature patients treated initially with intramedullary nailing for a tibia fracture who underwent a secondary intervention for delayed or nonunion were included. We also inquired about the use of any adjunct procedure performed at secondary intervention, such as fibulectomy. Infected nonunions and interventions other than dynamization or exchange nailing were excluded. Patients with significant bone loss treated initially with bone graft or spacers were also excluded, as were those treated with open grafting at the time of secondary intervention.
Chart Review The screening of patients varied by institution. At our home institution, patients were identified from billing records using current procedural terminology codes. Other sites used the same method or used previously established nonunion
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J Orthop Trauma Volume 29, Number 12, December 2015
databases. Additionally, the SPRINT database was screened to identify a subset of patients who underwent dynamization or exchange nailing. In the SPRINT trial, secondary procedures to gain union were disallowed for the first 6 months unless there was a fracture gap greater than 1 cm present after the index intramedullary nailing.15 Detailed reoperation data are available for these patients, and we were able to review these records of reoperation and identify patients meeting our inclusion criteria. All charts were reviewed for the following relevant data regarding demographics, injury, and fixations characteristics, and type and timing of interventions: 1. Demographics: Age, gender, smoking history, and presence of diabetes. 2. Injury characteristics: Mechanism of injury, fracture location, fracture pattern, and open or closed with associated Gustilo grade. 3. Fixation characteristics: Date of fixation, reamed versus unreamed nailing, and fracture gap, defined as a minimum 5 mm distraction in an area of no cortical contact. 4. Secondary interventions: Date and type of procedure (dynamization and exchange nailing).
Radiographic Evaluation The radiographic union score of tibias (RUST)22 was used to quantify healing at the time of index intervention and at the final follow-up. The RUST score is calculated from AP and lateral radiographs. Each cortex is given a score of 1 = no healing, 2 = callus present or bridging, or 3 = remodeled. These scores are summed for a total of 4–12. It is a previously validated score in the evaluation of tibial shaft fractures treated by intramedullary nailing.22,23 Success was defined per discretion of the attending surgeon, considering both radiographic and clinical presentation. Failure was defined as either the need for additional surgical intervention or lack of healing after secondary intervention.
Statistics Two-tailed t tests were performed to compare timing to intervention, time to union, RUST scores at intervention, RUST scores at union between tibia fractures treated with dynamization versus those treated with exchange nailing. Comparisons between categorical variables were performed with Fisher exact or x2 analysis where appropriate. These analyses were used to determine whether certain fracture characteristics influenced the indications or success of either secondary intervention.
Dynamizations and Exchanges
TABLE 1. Demographic Data Dynamizations (97) Age Range 18–82 Mean 39 Gender Female 29 Male 68 Smoking (179) Current/past 47 Nonsmokers 43 Diabetes (189) No 90 Yes (total) 6 IDDM 1 Mechanism (190) MVC 22 MCC 25 Pedestrian struck 16 Fall 19 Direct blow 9 Sports injury 2 GSW 2 Location (193) Metadiaphyseal 63 Diaphyseal 34 Fracture pattern (191) Oblique 31 Segmental 13 Transverse 24 Comminuted 29 Open vs. closed (194) Closed 34 Open 63 I 13 II 17 III (all) 27 IIIA 15 IIIB/C 11 Reamed vs. unreamed (188) Reamed 66 Unreamed 27 Presence of fracture gap (183) Present ($5 mm) 19 No gap 74
Exchanges (97)
P NS
16–72 39 0.04 16 81 NS 37 52 NS 84 9 3 NS 34 23 16 9 8 4 1 NS 60 36 0.002 20 8 12 54
* NS
41 56 6 16 31 21 10 NS 78 17 34 56
0.01 *
*More comminuted fractures and those with a gap receive exchange nail. NS, not significant.
RESULTS A total of 194 tibia fractures underwent dynamization (97) or exchange nailing (97) performed between 2001 and 2012. All interventions were performed in isolation and did not include the addition of fibulectomy or any other procedure. The average age was 39 years (16–81), and there were 149 men and 45 women. Mechanisms of injury were mitral valve area (56), MCA (48), pedestrian struck (32), falls (28), direct blow (17), and other (13). There were 119 open (49% grade III) and 75 closed fractures in the proximal (14%), Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
midshaft (39%), or distal (50%) tibia, including isolated and segmental fractures. Complete data regarding union were available for 179 tibias with 15 lost to follow-up.
Categorical Variables Analysis of demographic variables between patients undergoing dynamization versus exchange nailing is seen in Table 1. Results are based on the most complete data from our www.jorthotrauma.com |
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Litrenta et al
TABLE 2. Factors Affecting Success of Secondary Interventions Dynamization
N = 88
Exchange Nailing
N = 91
Success vs. open/closed fracture Success vs. fracture location Success vs. fracture pattern Success vs. fracture gap Dynamization vs. fracture gap Exchange nailing vs. fracture gap
P P P P P P
= = = = = =
1.00 0.37 0.07 0.02 0.06 0.09
series of 194 tibias; the exact number of complete data available for each variable is recorded here. We found that male patients were more likely to undergo exchange nailing than dynamization (P = 0.04); however, no other demographic variables significantly differed between the 2 groups. Also, there was no difference in the likelihood of undergoing exchange nailing or dynamization based on location (metaphyseal vs. diaphyseal fractures, P = 0.88) or open versus closed fractures (P = 0.29). However, regarding fracture pattern, comminuted fractures were more likely to undergo exchange nailing (P = 0.002). Additionally, fractures with a gap, identified after initial intramedullary nailing, were more likely to undergo exchange nailing than dynamization (P = 0.01). It is important to note that there was an association between comminuted fractures and those with a gap. In our series, 60% of fractures with a gap were characterized as comminuted compared with 38% without a gap. No other fracture pattern was associated with a fracture gap. The success or failure of either intervention was not different based on fracture location (metaphyseal vs. diaphyseal), open versus closed fractures, or fracture pattern. The presence of a fracture gap was a significantly negative predictor of success for all secondary interventions (78% vs. 92%, P = 0.02). In comparison of successful versus failed dynamizations, the presence of a gap was proportionately higher in failed dynamizations (P = 0.06). Similarly, the presence of a gap was more common although not statistically significant in failed exchange nailings (P = 0.09) (Table 2).
Continuous Variables Because the SPRINT study arbitrarily used 6 months as a cutoff for secondary intervention, we evaluated that time point as a potential factor in the success of interventions. The RUST scores at the time of intervention and the success rates of the interventions were not different for exchange nails (P = 0.43 and 0.3, respectively) or dynamizations (P = 0.96 and 0.75, respectively) performed before 6 months versus after 6 months,
allowing for pooling of the data. Fifteen patients were lost to follow-up leaving 179 fractures followed to union or failure. The median time to intervention was 157 days for dynamization and 192 days for exchange nailing. Union was achieved in 83% of dynamizations and 90% of exchange nails (P = 0.19) at a median time of 334 and 407 days after index procedure, respectively. RUST scores at the time of intervention were 7.1 for dynamization and 6.8 for exchange nails (P = 0.09, Table 3). RUST scores were also not different for successful or failed dynamizations (7.13 vs. 7.07, P = 0.83) or exchanges (6.8 vs. 7.3, P = 0.37). Likewise, the time to successful versus failed dynamization (165 vs. 158 days, P = 0.91) or exchange nailing (224 vs. 201 days, P = 0.48) was not different (Table 3). This represents less than 1 grade on 1 cortex difference in scoring.
DISCUSSION Tibial nonunion significantly impacts recovery and the ability to heal these fractures with the appropriate intervention is obviously desirable. There is little previous research to support dynamization. A small series by Wu and Shih16 demonstrated a success rate of 54% in 11 tibial nonunions treated 4–12 months after nailing. Although dynamization is a frequently used technique, there are no other larger series to support its use. Exchange nailing has gained more support in the literature, with success rates of 72%–96%.18–20 However, the largest of these series involved 33 patients with a success rate of 73%. Among those that failed, 55% had bone loss that required grafting and another 33% had distraction at the fracture site after the index nailing.18 Both Templeman and Court-Brown reported that bone loss had a negative effect on exchange nailing.18,19 No previous study has determined if other fracture characteristics may influence the surgeon’s preference or successful outcome of either technique. This study is the first large retrospective study regarding outcomes of dynamizations and exchange nailing. Overall, we found a high success rate for both interventions across a variety of fracture types and locations. In our analysis, we found that neither the location of the fracture nor whether the fracture was open versus closed influenced the choice of dynamization or exchange nailing across a large cross section. More importantly, we observed that these interventions are similar in terms of their success rates, supporting both procedures. One of our study goals was to determine the present indications for either procedure. We found that age, smoking status, diabetes, fracture location, and open or closed fractures did not affect surgeon’s choice of intervention. However, we did demonstrate that gender, comminution, and fracture gap
TABLE 3. Outcomes of Secondary Interventions Intervention
N
Median Days to Surgery (days)
RUST Preop
Union, n (%)
Median Time to Union (mo)
RUST Union
Dynamization Exchange P
88 91 NA
157 192 NA
7.1 6.8 0.09
73 (83) 82 (90) 0.19
11.1 13.4 NA
10.2 10.4 0.5
NA, not available.
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J Orthop Trauma Volume 29, Number 12, December 2015
may be a significant factor in the choice between interventions. Male patients, comminuted fractures, and those with a gap were more likely to undergo exchange nailing. These factors are somewhat related, as associated comminution represents a relatively higher percentage of fractures with a gap compared with those without a gap. We also sought to determine the factors associated with success of either procedure. Fracture location, open versus closed fractures, and fracture pattern did not affect the outcome. The only factor identified as significant was the presence of a fracture gap. Overall, the success in the face of a gap was 78% compared with 92% when no gap was present. The presence of a gap has previously been identified as a problem. In the SPRINT study, fractures that had no cortical contact (ie, an iatrogenic gap) were allowed to be dynamized to correct this technical error.15 Other studies demonstrated that among tibia fractures that failed exchange nailing, the primary reason was a need for bone graft secondary to bone loss.18,19 Our study defined a fracture gap as $5 mm of complete cortical discontinuity. We were not able to further characterize the gap precisely, as radiographic evaluation was limited after nailing, and these data were not available in all cases from operative reports. Further evaluation of the fracture gap is therefore needed to help surgeons identify fractures that may be better suited for exchange nailing. Furthermore, this is the first study to quantify radiographic parameters both at the time of intervention and at union. Previous work has demonstrated good inter- and intraobserver reliability of the RUST score but did not correlate scores with a clinical evidence of union.22,23 Our study demonstrated an average RUST score of 6.9 at the time of intervention for both dynamization and exchange and a RUST of 10.3 at the time of union. Clinically, a RUST score of 7 correlates with callus present on three-fourth of the cortices and a RUST of 10 indicates at least 2 remodeled cortices. Therefore, this suggests that orthopaedic surgeons intervene in the absence of any remodeled cortices or when two-fourth of the cortices demonstrate a lack of healing. A RUST score of 10 at union indicates that these healed fractures are remodeled on at least 2 cortices. Additionally, we found that RUST scores at the time of intervention were not predictive of success of either intervention. In summary, we found high rates of success for both dynamization and exchange nailing. Both techniques seem to have a role in the treatment of tibial nonunion. This conclusion is strengthened by the similarity in the timing of the interventions and the RUST scores at the index procedure. However, we did identify that comminuted fractures and those with a gap are more often treated with an exchange nail procedure. The only predictor of success was the presence of a fracture gap, and further work is needed to determine how various gaps and defects should be managed.
ACKNOWLEDGMENTS The authors thank Dr. Juan de Dios Robinson for his contributions of data collection and presentation of this research.
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Dynamizations and Exchanges
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