Title:Radiographic Characteristics of Volar Barton Distal Radius Fractures

Authors: Michael C. Daly, MD MSc1; Taylor A. Horst, MD2; Chaitanya S. Mudgal, MD2

Institutions:

1.Department of Orthopaedic Surgery

Harvard Combined Orthopaedic Residency Program

Massachusetts General Hospital

55 Fruit Street, White 535

Boston, MA 02114 USA

2.Hand and Upper Extremity Service

Department of Orthopaedic Surgery

Massachusetts General Hospital

55 Fruit Street, Lunder 2nd Floor Hand Clinic

Boston, MA 02114 USA

Email addresses:

Michael C. Daly:

Taylor A. Horst:

Chaitanya S. Mudgal:

Presenter (if accepted):

Michael C. Daly, MD MSc

Corresponding Author:

Chaitanya S. Mudgal, MD

Associate Professor in Orthopaedic Surgery

Harvard Medical School

Hand & Upper Extremity Service

Department of Orthopaedic Surgery

Massachusetts General Hospital

55 Fruit Street, Lunder 2nd Floor Hand Clinic

Boston, MA 02114 USA

Phone: +1-617-726-4700

Fax: +1-617-724-8532

Email:

Sources of Support that Require Acknowledgement:

No conflicts are declared.

Background: Volar Barton fractures are shearing fracturesinvolving the volar articular margin of the distal radius with proximal and volar subluxation of the carpus. In addition to the oblique fracture line through the volar articular surface, there may be a concomitant dorsal cortical break through the metaphysis of the distal radius. While the presence of an associated dorsal cortical break may have important treatment implications, they may be missed on plain radiographs and their frequency and epidemiology remain poorly characterized.

Purpose: This study aims to better characterize volar Barton distal radius fractures, with a specific focus on the dorsal cortical break (fracture line extending through the dorsal cortex of the metaphysis of the distal radius). To meet this aim, our study has three purposes: (1) to critically analyzefracture geometry on pre-operative CT scans of volar Barton distal radius fractures, (2) to determine the frequency of the presence of a dorsal cortical break, and (3) to test the null hypothesis that the presence of a dorsal cortical break is not associated with age or gender.

Methods: Weretrospectively reviewed the medical records of all patients with distal radius fracture treated surgically by a single fellowship-trained orthopedic hand surgeon between January2007 and July 2016 at anacademic tertiary care center. Patients 18 years of age and older with a shearing-type fracture of the volar articular margin of the distal radius accompanied by radiocarpal subluxation (OTA 23-B3 or OTA 23 type C) were included if they had a pre-operative CT scan and underwent surgery (CPT codes 25608 or 25609). We reviewed CT scans to analyze fracture geometry and determine the presence of a dorsal cortical break. Our main outcome measure was a binary variable indicating whether there was a dorsal cortical break; our main predictors were age and gender. We analyzed baseline variables using nonparametric bivariate statistics. Using multivariable logistic regression, we assessed whether age or gender were independent predictors of the presence of a dorsal cortical break.

Results: Of 290 patients with distal radius fractures treated operatively by a single surgeon (C.S.M.) over a nine and a half year period,we identified 40 adult patients (mean age 52 years, 57% female) who met selection critiera. All 40 (100%) were treated with volar plate fixation—33 (82.5%) were treated with avolar plate only; 7 (17.5%) were treated with additionalfragment-specific fixation. Including the shaft as a fragment, 32 (80%) had 3 or more discrete fracture fragments. When analyzing the volar fracture fragment by itself, we found 24(60%) had a longitudinal split. The main fracture line of the volar piece starts within the radiocarpal joint, involving an average of 44.9% of the scaphoid fossa (Figure 1A) and 50.1% of the lunate fossa (Figure 1B) as measured from the volar rim of the distal radius. The main fracture line of the volar piece extends proximally, exiting an average of 21.6 mm from the volar articular margin of the distal radius (Table 1, Figure 1A-C). On sagittal CT reconstructions, depression of the central articular surface was evident in 21 (52.5%) patients (Figure 1D). Thirty (75%) had a dorsal cortical break. Of those with a dorsal cortical break, the fracture line exited the dorsal metaphyseal cortex an average of 11.9±4.8 mm from the dorsal articular rim of the distal radius (Figure 1E). Comparing those with and without a dorsal cortical break, bivariate analysis demonstrated no difference in age (52.6±20.7 years versus 50.3±19 years, P=0.86, Wilcoxon rank sum test) or gender (82.6% female versus 64.7% male, P=0.27, Fisher’s exact test).Similarly, our multivariate analysis showed that neither age (OR, 0.98; 95% confidence interval [95% CI], 0.94–1.03; P=0.62) nor female gender (OR, 3.33; 95% CI, 0.57–23.18; P=0.19) were associated with the presence of a dorsal cortical break.

Conclusions: To the best of our knowledge, this is the largest single-surgeon series of surgically-treated volar Barton fractures of the distal radius. Our analysis of 40 patients with volar Barton distal radius fractures suggests:

  1. The majority (75%) of patients had a dorsal cortical break, which occurred an average of 11.9 mm from the dorsal articular rim of the distal radius.
  2. The presence of a dorsal cortical break was not statistically associated with age or gender, suggesting these fracture patterns may not be associated with osteoporosis as previously hypothesized by Harness et al in 2004 (1).
  3. Most (80%) had 3 or more discrete fracture fragments (including theshaft as a fragment), and in 60% of cases the volar piece had a longitudinal split. The multifragmentary nature of these injuries can affect surgical fixation strategy—in our study, 7 of 40 patients (17.5%) were treated with fragment-specific fixation in addition to a volar plate. The treating surgeon must be able to recognize separate fragments and be prepared to address them in a more fragment-specific manner if appropriate.

Our findings expand and refine our understanding of the radiographic pathoanatomy of volar Barton fractures of the distal radius, and suggest further study is warranted.

References:

  1. Harness N, Ring D, Jupiter JB. Volar Barton’s fractures with concomitant dorsal fracture in older patients. J Hand Surg Am. 2004 May;29(3):439–45.
  2. Souer JS, Ring D, Jupiter JB, Matschke S, Audige L, Marent-Huber M. Comparison of AO Type-B and Type-C volar shearing fractures of the distal part of the radius. J Bone Joint Surg Am. 2009 Nov;91(11):2605–11.
  3. Souer JS, Wiggers J, Ring D. Quantitative 3-dimensional computed tomography measurement of volar shearing fractures of the distal radius. J Hand Surg Am. 2011 Apr;36(4):599–603.
  4. Beck JD, Harness NG, Spencer HT. Volar plate fixation failure for volar shearing distal radius fractures with small lunate facet fragments. J Hand Surg Am. 2014 Apr;39(4):670–8.
  5. Kitay A, Mudgal C. Volar carpal subluxation following lunate facet fracture. J Hand Surg Am. 2014 Nov;39(11):2335–41.

Level of Evidence: IV

Keywords:Volar Barton; volar shearing fracture; volar rim fracture; distal radius fracture; dorsal fracture; dorsal cortical fracture; dorsal cortical break