- Email: [email protected]
Radial head fractures: Loss of cortical contact is associated with concomitant fracture or dislocation
J Shoulder Elbow Surg (2010) 19, 21-25
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Radial head fractures: Loss of cortical contact is associated with concomitant fracture or dislocation Craig A. Rineer, MDz, Thierry G. Guitton, MScz, David Ring, MD, PhD* Harvard Medical School, Orthopaedic Hand and Upper Extremity Service, Massachusetts General Hospital, Boston, MA, USA Hypothesis: Among radial head fractures displaced greater than 2 mm (Broberg and Morrey modified Mason type 2), separation (complete loss of cortical contact) of at least 1 radial head fracture fragment is associated with a complex injury pattern, meaning that there are other concomitant elbow fractures or ligament injuries. Materials and methods: We identified 291 consecutive skeletally mature patients with 296 radial head fractures treated during a 6-year period. Of these, 121 consecutive fractures of part of the radial head displaced greater than 2 mm (type 2) were classified according to whether there was complete lack of cortical contact between a fracture fragment and the rest of the proximal radius. Predictors of isolated vs complex injury pattern were sought in bivariate and multivariable analyses. Results: Of 121 fractures, 30 (25%) were classified as having cortical contact, and 91 (75%) were classified as not having cortical contact. Ten (33%) with cortical contact were part of a complex elbow injury, and 83 of 91 fractures (91%) without cortical contact were part of a complex elbow injury (P < .01). Among the Mason type 2 fractures, loss of cortical contact was a significant predictor of a complex elbow injury in both bivariate and multivariable analyses, with an odds ratio of 21 (95% confidence interval, 7-59). Conclusions: Among Mason type 2 fractures, complete loss of cortical contact of at least one fracture fragment is strongly predictive of a complex injury pattern. Level of evidence: 4, Retrospective case series, Treatment study. Ó 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Radial head fracture; dislocation; instability; displacement
Radial head fractures are usually classified according to the size and displacement of the fracture fragments.6,10,12 One important aspect of the injury that seems underrepresented is the stability of the fracture. We have found during operative exploration that most partial radial head fractures *Reprint requests: David Ring, MD PhD, Massachusetts General Hospital, Yawkey Center, Suite 2100, 55 Fruit Street, Boston, MA 02114. E-mail address: [email protected] (D. Ring). z Co-first author.
that are isolated (no other fractures or ligament injuries) are stable, with intact periosteum, and require force to realign. In contrast, most partial head fractures associated with other fractures or dislocations are unstable, have little soft tissue attachment, and often have comminution and lost fragments. According to our interpretation of the available data, stable fractures (minimally displaced) are straightforward to treat operatively and the results are very good.4,8,9,15 Unstable (displaced) fractures are much more challenging
1058-2746/2010/$36.00 - see front matter Ó 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2009.05.015
22 to repair and may not do as well.4,15,16 Perhaps stability is not included in classification systems because it is defined on the basis of operative exploration. We propose a radiographic definition of stability: complete loss of cortical contact between a fracture fragment and the rest of the proximal radius. This investigation documents the diagnostic characteristics of this radiographic definition of stability as an indicator of associated ligament injury or fracture.
Materials and methods The Massachusetts General Hospital Investigational Review Board approved the human protocol for this investigation (No. 1999P008705). All investigations were conducted in conformity with ethical principles of research, and informed consent for patient participation in the study was obtained. We retrospectively reviewed a prospective trauma database and billing records to identify consecutive fractures of the radial head seen at 2 level 1 trauma centers. Inclusion criteria were fracture of the radial head, skeletal maturity, and an adequate medical record, including radiographs. Exclusion criteria were fractures of the radial neck and occult radial head fractures diagnosed on the basis of interview, examination, and radiographic signs of an elbow joint effusion. We determined 296 fractures in 291 patients satisfied the inclusion and exclusion criteria. Medical records were reviewed retrospectively for gender, age, side, and ipsilateral upper extremity fractures or dislocations. The initial, nonstandardized radiographs obtained in the emergency department were used and the fractures were classified using a modification of Mason’s fracture classification according to Broberg and Morrey2 as follows: Type 1 are defined as fissure fractures or marginal sector fractures without displacement, type 2 are those with fragments involving at least 30% of the articular surface displaced more than 2 mm, and type 3 are comminuted fractures involving the entire head.12 The overall injury pattern was classified as (1) isolated, no other fractures or ligament injuries apparent; (2) elbow dislocation, (3) terrible triad fracture-dislocation (dislocation with fractures of the coronoid and radial head); (4) nonarticular (Jupiter type B or C) posterior Monteggia type fracture-dislocation; (5) posterior olecranon fracture-dislocation (Jupiter type A), (6) Essex-Lopresti fracture-dislocation, or (7) ‘‘other complex’’ injury, which consisted of a radial head fracture in addition of a capitellum fracture in 1 patient and a lateral column with capitellum and lateral trochlea fracture in another. One patient had a radial head fracture with medial collateral ligament (MCL) injury, and 2 patients had an additional coronoid fracture. Radial head fractures were classified by whether there was complete loss of cortical contact of at least 1 radial head fracture fragment with the rest of the proximal radius. Bivariate and multivariable predictors of isolated vs complex injury pattern among the Mason type 2 fractures were sought from among the loss of cortical contact, presence of ipsilateral upper extremity fractures/dislocations, gender, or age. Cohen’s k was used to calculate measures of reliability (interobserver agreement) of distinguishing lack of cortical contact of at least 1 radial head fragment and the Mason classification as classified by two different observers (D.R. and T.G.; Fig. 1). The senior author
C.A. Rineer et al. reviewed all discrepancies, and a final determination was made. The intraobserver agreement was not measured.
Results Among the 296 fractures, the mean age was 45 16 (SD) years (range, 15-90 years). A total of 133 fractures (45%) were Mason type 1, 121 (41%) were Mason type 2, and 42 (14%) were Mason type 3. The study comprised 154 men (52%) and 142 women (48%). The male-to-female ratio was close to 1:1 for all fractures, Mason type 1 fractures, Mason type 2 fractures, and fractures with cortical contact. There were 163 fractures (55%) classified as having cortical contact, and 133 (45%) were classified as not having cortical contact. Comparison of the Mason classification with the cortical contact classification revealed that the 133 Mason type 1 fractures by definition had cortical contact and the 42 Mason type 3 fractures were classified as not having cortical contact. Among the Mason type 2 fractures, 30 (25%) were classified as having cortical contact and 91 (75%) were classified as not having cortical contact (Table I). The mean age of patients was 42 years for Mason type 1 fractures, 48 years for Mason type 2, and 52 years for Mason type 3 (P < .01; analysis of variance). The mean age of patients with cortical contact was 42 years, and that of patients without cortical contact was 49 years (P < .01; t test). There were no statistically significant differences in fracture types or cortical contact between men and women. The radial head fracture was an isolated elbow injury in 152 fractures (51%), whereas the fracture in the other 144 (49%) was part of a complex elbow injury pattern, the most common of which was the terrible triad fracture-dislocation occurring in 59 patients (19.9%). There were 41 posterior olecranon fracture-dislocations (13.9%), 25 elbow dislocations (8.4%), 13 posterior Monteggia fracture-dislocations (4.4%), 5 other complex injuries (1.7%), and 1 EssexLopresti fracture-dislocation (0.3%). The radial head fracture was a probable isolated elbow injury in 93% of the Mason type 1 fractures, 23% of the Mason type 2 fractures, and 0% of the Mason type 3 fractures (P < .01; c2 test). Among the fractures with cortical contact, the radial head fracture was an isolated elbow injury in 88% but was isolated in only 6% of the fractures without cortical contact (P < .01; c2 test). Eight of the 9 complex elbow injury patterns in the Mason type 1 fractures were elbow dislocations without fracture of the coronoid. The 13 fractures associated with Monteggia injuries were Mason type 2; none were Mason type 3. Eleven of the 13 Monteggia injuries were classified as not having cortical contact. Among the 59 terrible triad fracture-dislocations, 37 were Mason type 2, 22 were Mason type 3, and 56 were classified as not having cortical contact (Table II). The 5 other complex elbow injury patterns consisted of 1 patient with a radial head fracture and large capitellar fracture; 2 patients with radial head and coronoid fractures
Radial head fractures
23
Figure 1 Lack of contact as a method for distinguishing radial head fractures associated with other injuries to the elbow or forearm. (A) The fracture fragments are in contact. There were no other ligament injuries or fractures. (B) The fractured radial head is displaced so that there is a gap between the fragment and the intact radial head. (C) There is a comminuted intra-articular radial head fracture. A portion of the radial head is significantly displaced posteriorly and lacks cortical contact with the rest of the radius.
but no elbow dislocation; 1 patient with distal humerus, radial head, and proximal ulna fractures; and 1 patient with a radial head fracture and gross medial collateral ligament laxity but no dislocation. Forty-four patients (15%) had ipsilateral separate upper extremity fractures/dislocations. An ipsilateral fracture or dislocation was present in 12 of 133 patients with type 1, in 23 of 121 with type 2, and in 9 of 42 with type 3 (P ¼ .036; c2 test). An ipsilateral fracture or dislocation was present in 17 of 163 patients with cortical contact and in 27 of 133 patients without cortical contact (P ¼ .018; c2 test). The most common ipsilateral upper extremity fractures/dislocations were distal radius fractures, occurring in 14 cases, followed by distal humerus fractures in 10 cases. The Cohen k for lack of cortical contact of at least 1 radial head fragment was k ¼ 0.22; (fair agreement) and for the Mason classification, k ¼ 0.44 (moderate agreement).
Broberg and Morrey modified Mason type 2 fractures Among the 121 Mason type 2 fractures, 30 fractures had cortical contact and 91 did not. Among these 91 unstable fractures, there were 8 isolated fractures (9%), 14 elbow dislocations (15.4%), 20 posterior olecranon fractureTable I
Totals of fracture types Stable
Unstable
Total
Type
No.
No.
No.
Mason 1 Mason 2 Mason 3 Total
133 30 . 163
. 91 42 133
133 121 42 296
24 Table II
C.A. Rineer et al. Fracture type with fracture pattern and stability Isolated
Mas
Elbow dislocation POFD
Monteggia
Terrible triad FD Esesx-Lopresti FD Other complex
Stable Unstable Stable Unstable Stable Unstable Stable Unstable Stable Unstable Stable Unstable Stable Unstable
Mason 1 124 Mason 2 20 Mason 3 . Total 144
. 8 . 8
8 . . 8
. 14 3 17
. 4 . 4
. 20 17 41
. 2 . 2
. 11 . 11
. 3 . 3
. 34 22 56
. . . .
. 1 . 1
1 1 . 2
. 3 . 3
FD, Facture dislocation; POFD, posterior olecranon fracture-dislocation.
dislocations (22%), 11 Monteggia fracture-dislocations (12%), 34 terrible triad injuries (37.4%), 1 Essex-Lopresti fracture dislocation (1%), and 3 other complex injuries (3.2%). Comparison of these 2 groups showed no statistically significant differences in age, gender distribution, or percentage with ipsilateral injuries. Among the fractures with cortical contact, the radial head fracture was an isolated elbow injury in 67% but was isolated in only 9% of the fractures without cortical contact (P < .01; c2 test). In multivariable logistic regression (pseudo-R2 ¼ 0.29, P < .01) with the 121 Mason type 2 patients, the odds ratio of a complex injury pattern with loss of cortical contact was 21 (95% confidence interval, 7-59). Loss of cortical contact as a test for complex elbow injury had a sensitivity of 0.71, specificity of 0.89, positive predictive value of 0.67, negative predictive value of 0.91, and an accuracy of 0.85.
Discussion Classification systems for radial head fractures distinguish partial and whole head involvement and sometimes account for fracture size and displacement, but the overall injury pattern and the stability of the fracture are not considered.6,10,12 Stability is difficult to include because it is best defined on the basis of operative exploration. Our data suggest that a radiographic surrogate for stability correlates with complex fracture-dislocations of the elbow and proximal ulna. This study had several limitations in addition to those typical of retrospective reviews of medical records. First, the reliability of classifying radial head fractures as having or lacking cortical contact is only fair, and the classification of Mason type is only moderate. It is possible that the idea of using radial head fragment displacement as a marker of a more complex injury may prove most useful in the obvious cases. Second, the retrospective nature of this study meant there was no set of standardized imaging and only a subset of the more complex injuries had computed tomography (CT) scans. Third, it is possible that the dislocated the elbow or forearm in some patients spontaneously relocated before the initial radiographic evaluation, resulting in ligament injuries that were not detectable on static radiographs and would have more appropriately been classified as complex injuries.3,11
Thus, our approach risks underestimating the prevalence of complex injuries; however, we doubt that there is a large number of patients in this category. In contrast, Itamura et al5 evaluated ligament injury on magnetic resonance imaging. We determined it was more relevant to focus on radiographically documented fractures and dislocations associated with fracture of the radial head, because the lesser grades of ligament, chondral, or bony injuries that were detected by Itamura et al5 have unclear clinical significance. Finally, we did not use intraoperative evaluation as a reference standard and can only comment on the relationship between radiographic findings and known complex injury patterns based on the initial set of postinjury radiographs. In addition, we agree that cortical contact is, at best, a surrogate measure for the much more complex concept of an unstable vs a stable fracture fragment, and the correspondence of instability with a complex injury pattern is not perfect. Although nondisplaced stable fractures are very straightforward to treat operatively and the results are very good,4,8,9,15 displaced unstable fractures can be more challenging and may not do as well.4,15,16 In the setting of a dislocation with radial head fracture, reasonable results were obtained with radial head resection and cast immobilization.1,7 The same is true for many olecranon fracturedislocations and posterior Monteggia injuries13; however, when there was also a coronoid fracture, the elbow is very unstable.14 We conclude from our data that Mason type 2 radial head fractures with at least 1 fracture fragment with no cortical contact are 21-times more likely than fractures with cortical contact to be associated with a complex injury pattern. It has been stressed with Mason type 3 fractures that if imaging studies fail to demonstrate the presence of a complex elbow injury pattern, the surgeon should still have a high suspicion that some degree of occult instability may be present. The current study indicates that this concept should be extended to any radial head fracture that lacks cortical contact with the rest of the proximal radius.
Disclaimer Dr Ring is a consultant for Wright Medical, Acumed, and Tornier. Research support was received from all three companies.
Radial head fractures
References 1. Broberg MA, Morrey BF. Results of delayed excision of the radial head after fracture. J Bone Joint Surg Am 1986;68:669-74. 2. Broberg MA, Morrey BF. Results of treatment of fracture-dislocations of the elbow. Clin Orthop Relat Res 1987:109-19. 3. Doornberg J, Elsner A, Kloen P, Marti RK, van Dijk CN, Ring D. Apparently isolated partial articular fractures of the radial head: prevalence and reliability of radiographically diagnosed displacement. J Shoulder Elbow Surg 2007;16:603-8. 4. Esser RD, Davis S, Taavao T. Fractures of the radial head treated by internal fixation: late results in 26 cases. J Orthop Trauma 1995;9: 318-23. 5. Itamura J, Roidis N, Mirzayan R, Vaishnav S, Learch T, Shean C. Radial head fractures: MRI evaluation of associated injuries. J Shoulder Elbow Surg 2005;14:421-4. 6. Johnston GW. A follow-up of one hundred cases of fracture of the head of the radius with a review of the literature. Ulster Med J 1962; 31:51-6. 7. Josefsson PO, Gentz CF, Johnell O, Wendeberg B. Dislocations of the elbow and intraarticular fractures. Clin Orthop Relat Res 1989: 126-30.
25 8. Khalfayan EE, Culp RW, Alexander AH. Mason type II radial head fractures: operative versus nonoperative treatment. J Orthop Trauma 1992;6:283-9. 9. King GJ, Evans DC, Kellam JF. Open reduction and internal fixation of radial head fractures. J Orthop Trauma 1991;5:21-8. 10. Mason ML. Some observations on fractures of the head of the radius with a review of one hundred cases. Br J Surg 1954;42:123-32. 11. Morgan SJ, Groshen SL, Itamura JM, Shankwiler J, Brien WW, Kuschner SH. Reliability evaluation of classifying radial head fractures by the system of Mason. Bull Hosp Jt Dis 1997;56:95-8. 12. Morrey B. Radial head fractures. In: BF M, editor. The elbow and its disorders. Philadelphia: WB Saunders; 1985. p. 355-81. 13. O’Driscoll SW, Jupiter JB, King GJ, Hotchkiss RN, Morrey BF. The unstable elbow. Instr Course Lect 2001;50:89-102. 14. Ring D, Jupiter JB, Zilberfarb J. Posterior dislocation of the elbow with fractures of the radial head and coronoid. J Bone Joint Surg Am 2002;84:547-51. 15. Ring D, Quintero J, Jupiter JB. Open reduction and internal fixation of fractures of the radial head. J Bone Joint Surg Am 2002;84: 1811-5. 16. Ruan HJ, Fan CY, Liu JJ, Zeng BF. A comparative study of internal fixation and prosthesis replacement for radial head fractures of Mason type III. Int Orthop 2009;33:249-53.
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Radial head fractures: Loss of cortical contact is associated with concomitant fracture or dislocation Craig A. Rineer, MDz, Thierry G. Guitton, MScz, David Ring, MD, PhD* Harvard Medical School, Orthopaedic Hand and Upper Extremity Service, Massachusetts General Hospital, Boston, MA, USA Hypothesis: Among radial head fractures displaced greater than 2 mm (Broberg and Morrey modified Mason type 2), separation (complete loss of cortical contact) of at least 1 radial head fracture fragment is associated with a complex injury pattern, meaning that there are other concomitant elbow fractures or ligament injuries. Materials and methods: We identified 291 consecutive skeletally mature patients with 296 radial head fractures treated during a 6-year period. Of these, 121 consecutive fractures of part of the radial head displaced greater than 2 mm (type 2) were classified according to whether there was complete lack of cortical contact between a fracture fragment and the rest of the proximal radius. Predictors of isolated vs complex injury pattern were sought in bivariate and multivariable analyses. Results: Of 121 fractures, 30 (25%) were classified as having cortical contact, and 91 (75%) were classified as not having cortical contact. Ten (33%) with cortical contact were part of a complex elbow injury, and 83 of 91 fractures (91%) without cortical contact were part of a complex elbow injury (P < .01). Among the Mason type 2 fractures, loss of cortical contact was a significant predictor of a complex elbow injury in both bivariate and multivariable analyses, with an odds ratio of 21 (95% confidence interval, 7-59). Conclusions: Among Mason type 2 fractures, complete loss of cortical contact of at least one fracture fragment is strongly predictive of a complex injury pattern. Level of evidence: 4, Retrospective case series, Treatment study. Ó 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Radial head fracture; dislocation; instability; displacement
Radial head fractures are usually classified according to the size and displacement of the fracture fragments.6,10,12 One important aspect of the injury that seems underrepresented is the stability of the fracture. We have found during operative exploration that most partial radial head fractures *Reprint requests: David Ring, MD PhD, Massachusetts General Hospital, Yawkey Center, Suite 2100, 55 Fruit Street, Boston, MA 02114. E-mail address: [email protected] (D. Ring). z Co-first author.
that are isolated (no other fractures or ligament injuries) are stable, with intact periosteum, and require force to realign. In contrast, most partial head fractures associated with other fractures or dislocations are unstable, have little soft tissue attachment, and often have comminution and lost fragments. According to our interpretation of the available data, stable fractures (minimally displaced) are straightforward to treat operatively and the results are very good.4,8,9,15 Unstable (displaced) fractures are much more challenging
1058-2746/2010/$36.00 - see front matter Ó 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2009.05.015
22 to repair and may not do as well.4,15,16 Perhaps stability is not included in classification systems because it is defined on the basis of operative exploration. We propose a radiographic definition of stability: complete loss of cortical contact between a fracture fragment and the rest of the proximal radius. This investigation documents the diagnostic characteristics of this radiographic definition of stability as an indicator of associated ligament injury or fracture.
Materials and methods The Massachusetts General Hospital Investigational Review Board approved the human protocol for this investigation (No. 1999P008705). All investigations were conducted in conformity with ethical principles of research, and informed consent for patient participation in the study was obtained. We retrospectively reviewed a prospective trauma database and billing records to identify consecutive fractures of the radial head seen at 2 level 1 trauma centers. Inclusion criteria were fracture of the radial head, skeletal maturity, and an adequate medical record, including radiographs. Exclusion criteria were fractures of the radial neck and occult radial head fractures diagnosed on the basis of interview, examination, and radiographic signs of an elbow joint effusion. We determined 296 fractures in 291 patients satisfied the inclusion and exclusion criteria. Medical records were reviewed retrospectively for gender, age, side, and ipsilateral upper extremity fractures or dislocations. The initial, nonstandardized radiographs obtained in the emergency department were used and the fractures were classified using a modification of Mason’s fracture classification according to Broberg and Morrey2 as follows: Type 1 are defined as fissure fractures or marginal sector fractures without displacement, type 2 are those with fragments involving at least 30% of the articular surface displaced more than 2 mm, and type 3 are comminuted fractures involving the entire head.12 The overall injury pattern was classified as (1) isolated, no other fractures or ligament injuries apparent; (2) elbow dislocation, (3) terrible triad fracture-dislocation (dislocation with fractures of the coronoid and radial head); (4) nonarticular (Jupiter type B or C) posterior Monteggia type fracture-dislocation; (5) posterior olecranon fracture-dislocation (Jupiter type A), (6) Essex-Lopresti fracture-dislocation, or (7) ‘‘other complex’’ injury, which consisted of a radial head fracture in addition of a capitellum fracture in 1 patient and a lateral column with capitellum and lateral trochlea fracture in another. One patient had a radial head fracture with medial collateral ligament (MCL) injury, and 2 patients had an additional coronoid fracture. Radial head fractures were classified by whether there was complete loss of cortical contact of at least 1 radial head fracture fragment with the rest of the proximal radius. Bivariate and multivariable predictors of isolated vs complex injury pattern among the Mason type 2 fractures were sought from among the loss of cortical contact, presence of ipsilateral upper extremity fractures/dislocations, gender, or age. Cohen’s k was used to calculate measures of reliability (interobserver agreement) of distinguishing lack of cortical contact of at least 1 radial head fragment and the Mason classification as classified by two different observers (D.R. and T.G.; Fig. 1). The senior author
C.A. Rineer et al. reviewed all discrepancies, and a final determination was made. The intraobserver agreement was not measured.
Results Among the 296 fractures, the mean age was 45 16 (SD) years (range, 15-90 years). A total of 133 fractures (45%) were Mason type 1, 121 (41%) were Mason type 2, and 42 (14%) were Mason type 3. The study comprised 154 men (52%) and 142 women (48%). The male-to-female ratio was close to 1:1 for all fractures, Mason type 1 fractures, Mason type 2 fractures, and fractures with cortical contact. There were 163 fractures (55%) classified as having cortical contact, and 133 (45%) were classified as not having cortical contact. Comparison of the Mason classification with the cortical contact classification revealed that the 133 Mason type 1 fractures by definition had cortical contact and the 42 Mason type 3 fractures were classified as not having cortical contact. Among the Mason type 2 fractures, 30 (25%) were classified as having cortical contact and 91 (75%) were classified as not having cortical contact (Table I). The mean age of patients was 42 years for Mason type 1 fractures, 48 years for Mason type 2, and 52 years for Mason type 3 (P < .01; analysis of variance). The mean age of patients with cortical contact was 42 years, and that of patients without cortical contact was 49 years (P < .01; t test). There were no statistically significant differences in fracture types or cortical contact between men and women. The radial head fracture was an isolated elbow injury in 152 fractures (51%), whereas the fracture in the other 144 (49%) was part of a complex elbow injury pattern, the most common of which was the terrible triad fracture-dislocation occurring in 59 patients (19.9%). There were 41 posterior olecranon fracture-dislocations (13.9%), 25 elbow dislocations (8.4%), 13 posterior Monteggia fracture-dislocations (4.4%), 5 other complex injuries (1.7%), and 1 EssexLopresti fracture-dislocation (0.3%). The radial head fracture was a probable isolated elbow injury in 93% of the Mason type 1 fractures, 23% of the Mason type 2 fractures, and 0% of the Mason type 3 fractures (P < .01; c2 test). Among the fractures with cortical contact, the radial head fracture was an isolated elbow injury in 88% but was isolated in only 6% of the fractures without cortical contact (P < .01; c2 test). Eight of the 9 complex elbow injury patterns in the Mason type 1 fractures were elbow dislocations without fracture of the coronoid. The 13 fractures associated with Monteggia injuries were Mason type 2; none were Mason type 3. Eleven of the 13 Monteggia injuries were classified as not having cortical contact. Among the 59 terrible triad fracture-dislocations, 37 were Mason type 2, 22 were Mason type 3, and 56 were classified as not having cortical contact (Table II). The 5 other complex elbow injury patterns consisted of 1 patient with a radial head fracture and large capitellar fracture; 2 patients with radial head and coronoid fractures
Radial head fractures
23
Figure 1 Lack of contact as a method for distinguishing radial head fractures associated with other injuries to the elbow or forearm. (A) The fracture fragments are in contact. There were no other ligament injuries or fractures. (B) The fractured radial head is displaced so that there is a gap between the fragment and the intact radial head. (C) There is a comminuted intra-articular radial head fracture. A portion of the radial head is significantly displaced posteriorly and lacks cortical contact with the rest of the radius.
but no elbow dislocation; 1 patient with distal humerus, radial head, and proximal ulna fractures; and 1 patient with a radial head fracture and gross medial collateral ligament laxity but no dislocation. Forty-four patients (15%) had ipsilateral separate upper extremity fractures/dislocations. An ipsilateral fracture or dislocation was present in 12 of 133 patients with type 1, in 23 of 121 with type 2, and in 9 of 42 with type 3 (P ¼ .036; c2 test). An ipsilateral fracture or dislocation was present in 17 of 163 patients with cortical contact and in 27 of 133 patients without cortical contact (P ¼ .018; c2 test). The most common ipsilateral upper extremity fractures/dislocations were distal radius fractures, occurring in 14 cases, followed by distal humerus fractures in 10 cases. The Cohen k for lack of cortical contact of at least 1 radial head fragment was k ¼ 0.22; (fair agreement) and for the Mason classification, k ¼ 0.44 (moderate agreement).
Broberg and Morrey modified Mason type 2 fractures Among the 121 Mason type 2 fractures, 30 fractures had cortical contact and 91 did not. Among these 91 unstable fractures, there were 8 isolated fractures (9%), 14 elbow dislocations (15.4%), 20 posterior olecranon fractureTable I
Totals of fracture types Stable
Unstable
Total
Type
No.
No.
No.
Mason 1 Mason 2 Mason 3 Total
133 30 . 163
. 91 42 133
133 121 42 296
24 Table II
C.A. Rineer et al. Fracture type with fracture pattern and stability Isolated
Mas
Elbow dislocation POFD
Monteggia
Terrible triad FD Esesx-Lopresti FD Other complex
Stable Unstable Stable Unstable Stable Unstable Stable Unstable Stable Unstable Stable Unstable Stable Unstable
Mason 1 124 Mason 2 20 Mason 3 . Total 144
. 8 . 8
8 . . 8
. 14 3 17
. 4 . 4
. 20 17 41
. 2 . 2
. 11 . 11
. 3 . 3
. 34 22 56
. . . .
. 1 . 1
1 1 . 2
. 3 . 3
FD, Facture dislocation; POFD, posterior olecranon fracture-dislocation.
dislocations (22%), 11 Monteggia fracture-dislocations (12%), 34 terrible triad injuries (37.4%), 1 Essex-Lopresti fracture dislocation (1%), and 3 other complex injuries (3.2%). Comparison of these 2 groups showed no statistically significant differences in age, gender distribution, or percentage with ipsilateral injuries. Among the fractures with cortical contact, the radial head fracture was an isolated elbow injury in 67% but was isolated in only 9% of the fractures without cortical contact (P < .01; c2 test). In multivariable logistic regression (pseudo-R2 ¼ 0.29, P < .01) with the 121 Mason type 2 patients, the odds ratio of a complex injury pattern with loss of cortical contact was 21 (95% confidence interval, 7-59). Loss of cortical contact as a test for complex elbow injury had a sensitivity of 0.71, specificity of 0.89, positive predictive value of 0.67, negative predictive value of 0.91, and an accuracy of 0.85.
Discussion Classification systems for radial head fractures distinguish partial and whole head involvement and sometimes account for fracture size and displacement, but the overall injury pattern and the stability of the fracture are not considered.6,10,12 Stability is difficult to include because it is best defined on the basis of operative exploration. Our data suggest that a radiographic surrogate for stability correlates with complex fracture-dislocations of the elbow and proximal ulna. This study had several limitations in addition to those typical of retrospective reviews of medical records. First, the reliability of classifying radial head fractures as having or lacking cortical contact is only fair, and the classification of Mason type is only moderate. It is possible that the idea of using radial head fragment displacement as a marker of a more complex injury may prove most useful in the obvious cases. Second, the retrospective nature of this study meant there was no set of standardized imaging and only a subset of the more complex injuries had computed tomography (CT) scans. Third, it is possible that the dislocated the elbow or forearm in some patients spontaneously relocated before the initial radiographic evaluation, resulting in ligament injuries that were not detectable on static radiographs and would have more appropriately been classified as complex injuries.3,11
Thus, our approach risks underestimating the prevalence of complex injuries; however, we doubt that there is a large number of patients in this category. In contrast, Itamura et al5 evaluated ligament injury on magnetic resonance imaging. We determined it was more relevant to focus on radiographically documented fractures and dislocations associated with fracture of the radial head, because the lesser grades of ligament, chondral, or bony injuries that were detected by Itamura et al5 have unclear clinical significance. Finally, we did not use intraoperative evaluation as a reference standard and can only comment on the relationship between radiographic findings and known complex injury patterns based on the initial set of postinjury radiographs. In addition, we agree that cortical contact is, at best, a surrogate measure for the much more complex concept of an unstable vs a stable fracture fragment, and the correspondence of instability with a complex injury pattern is not perfect. Although nondisplaced stable fractures are very straightforward to treat operatively and the results are very good,4,8,9,15 displaced unstable fractures can be more challenging and may not do as well.4,15,16 In the setting of a dislocation with radial head fracture, reasonable results were obtained with radial head resection and cast immobilization.1,7 The same is true for many olecranon fracturedislocations and posterior Monteggia injuries13; however, when there was also a coronoid fracture, the elbow is very unstable.14 We conclude from our data that Mason type 2 radial head fractures with at least 1 fracture fragment with no cortical contact are 21-times more likely than fractures with cortical contact to be associated with a complex injury pattern. It has been stressed with Mason type 3 fractures that if imaging studies fail to demonstrate the presence of a complex elbow injury pattern, the surgeon should still have a high suspicion that some degree of occult instability may be present. The current study indicates that this concept should be extended to any radial head fracture that lacks cortical contact with the rest of the proximal radius.
Disclaimer Dr Ring is a consultant for Wright Medical, Acumed, and Tornier. Research support was received from all three companies.
Radial head fractures
References 1. Broberg MA, Morrey BF. Results of delayed excision of the radial head after fracture. J Bone Joint Surg Am 1986;68:669-74. 2. Broberg MA, Morrey BF. Results of treatment of fracture-dislocations of the elbow. Clin Orthop Relat Res 1987:109-19. 3. Doornberg J, Elsner A, Kloen P, Marti RK, van Dijk CN, Ring D. Apparently isolated partial articular fractures of the radial head: prevalence and reliability of radiographically diagnosed displacement. J Shoulder Elbow Surg 2007;16:603-8. 4. Esser RD, Davis S, Taavao T. Fractures of the radial head treated by internal fixation: late results in 26 cases. J Orthop Trauma 1995;9: 318-23. 5. Itamura J, Roidis N, Mirzayan R, Vaishnav S, Learch T, Shean C. Radial head fractures: MRI evaluation of associated injuries. J Shoulder Elbow Surg 2005;14:421-4. 6. Johnston GW. A follow-up of one hundred cases of fracture of the head of the radius with a review of the literature. Ulster Med J 1962; 31:51-6. 7. Josefsson PO, Gentz CF, Johnell O, Wendeberg B. Dislocations of the elbow and intraarticular fractures. Clin Orthop Relat Res 1989: 126-30.
25 8. Khalfayan EE, Culp RW, Alexander AH. Mason type II radial head fractures: operative versus nonoperative treatment. J Orthop Trauma 1992;6:283-9. 9. King GJ, Evans DC, Kellam JF. Open reduction and internal fixation of radial head fractures. J Orthop Trauma 1991;5:21-8. 10. Mason ML. Some observations on fractures of the head of the radius with a review of one hundred cases. Br J Surg 1954;42:123-32. 11. Morgan SJ, Groshen SL, Itamura JM, Shankwiler J, Brien WW, Kuschner SH. Reliability evaluation of classifying radial head fractures by the system of Mason. Bull Hosp Jt Dis 1997;56:95-8. 12. Morrey B. Radial head fractures. In: BF M, editor. The elbow and its disorders. Philadelphia: WB Saunders; 1985. p. 355-81. 13. O’Driscoll SW, Jupiter JB, King GJ, Hotchkiss RN, Morrey BF. The unstable elbow. Instr Course Lect 2001;50:89-102. 14. Ring D, Jupiter JB, Zilberfarb J. Posterior dislocation of the elbow with fractures of the radial head and coronoid. J Bone Joint Surg Am 2002;84:547-51. 15. Ring D, Quintero J, Jupiter JB. Open reduction and internal fixation of fractures of the radial head. J Bone Joint Surg Am 2002;84: 1811-5. 16. Ruan HJ, Fan CY, Liu JJ, Zeng BF. A comparative study of internal fixation and prosthesis replacement for radial head fractures of Mason type III. Int Orthop 2009;33:249-53.