Correlation Between Radiological Parameters and Functional Outcomes in Patients Older Than 60 Years of Age With Distal Radius Fracture

Abstract

Background: The relationship between radiographic and functional outcomes is controversial in the elderly. The objective of this study is to determine whether there is a correlation between functional outcome and acceptable distal radius fracture (DRF) alignment in patients older than 60 years of age. Methods: This correlation study was carried out at the Central Metropolitan Health Service of Chile. A total of 180 patients diagnosed with extra-articular DRF, according to the AO classification, were prospectively recruited. Radiological parameters, including radial inclination, residual dorsal angulation, ulnar variance, and articular step-off, were evaluated to assess the results of orthopedic reduction. Functional outcome was assessed immediately following cast removal and again at the 6-month follow-up. The Disabilities of the Arm, Shoulder and Hand (DASH) and Patient-Rated Wrist Evaluation (PRWE) questionnaires were administered to assess upper extremity function, and the visual analog scale (VAS) was used to assess pain intensity. Results: Only 68 patients (37.8%) showed acceptable DRF alignment. After cast removal, the correlations between alignment and the functional outcome measures were as follows: DASH 0.071 (P = .546), PRWE 0.03 (P = .823), and VAS 0.12 (P = .631). At the 6-month follow-up, the correlations between alignment and the functional outcome measures were as follows: DASH 0.029 (P = .768), PRWE 0.014 (P = .895), and VAS 0.09 (P = .614). Conclusions: There was no significant correlation between acceptable alignment according to radiological parameters and short- or medium-term functional outcome in patients older than 60 years with extra-articular DRF treated conservatively.

Introduction

Distal radius fractures (DRF) are among the most common musculoskeletal injuries, representing 15% to 20% of total fractures treated in emergency services.⁸ Epidemiologic studies have reported a high incidence in white populations, especially among elderly patients.³² DRF in patients older than 60 years is typically treated conservatively with closed reduction and plaster cast immobilization.¹² However, this treatment method frequently fails to maintain reduction, and redisplacement and malunion rates of over 50% have been reported in this population,³³ as age is a major risk factor for loss of reduction and secondary fracture displacement.^22,27,33,38

Some studies have reported that restoration of normal radiological parameters is an important factor in predicting a positive functional outcome after fracture.^2,4,16,27,39 The most frequent radiological parameters for evaluating extra-articular DRF reduction include radial inclination, radial height, volar tilt, ulnar variance, and articular step-off.^{13,22,24,27,33,38} Reports of direct correlations between radiological parameters and functional outcome are often cited to support the choice of orthopedic surgery over conservative treatment.^7,24,34,40 Nevertheless, current evidence indicates that in elderly patients, there are no clinically significant differences between conservative treatment and the different types of surgical interventions available for DRF.^11,14,19 These findings suggest that in this population, restoration of normal radiological parameters may not predict positive functional results and that clinical outcome may be unrelated to the final anatomical position of the healed fracture.^10,42 In fact, improvements in function and quality of life in this age group seem to be independent of residual deformity.^{3,5,14,19,41,42}

The main objective of the present investigation is to determine whether there is a correlation between acceptable DRF alignment according to radiological parameters and functional outcome, either immediately after cast removal or at 6 month follow-up, in patients older than 60 years of age treated with closed reduction and plaster cast immobilization.

Materials and Methods

This correlation study was approved by the Ethics Committee of the Central Metropolitan Health Service of Chile. Between 2012 and 2016, 180 patients older than 60 years of age who were diagnosed with an extra-articular DRF were recruited prospectively. The AO classification system was used to evaluate the type of fracture. The diagnosis was performed by an orthopedic surgeon, based on clinical presentation and radiological results. The initial closed reduction was performed under the supervision of the resident orthopedic surgeon; then, all patients were immobilized with plaster cast for 6 to 7 weeks, and 3-point index was applied to evaluate the displacement of the DRF.¹ After cast removal, all patients were prescribed acetaminophen (500 mg, every 8 hours, for 7 days) and referred for physical therapy.

Inclusion and Exclusion Criteria

The following patient inclusion criteria were applied:

• Patients older than 60 years who had no history of wrist fractures; diagnosed with an extra-articular DRF according to the AO classification; and treated conservatively with closed reduction and plaster cast immobilization.

• Written informed consent for all study participation provided by patient.

The following patient exclusion criteria were applied:

• Treatment with any type of surgical intervention for DRF reduction and/or fixation, such as volar plate, external fixator, and Kirschner wires.

• Immediate complications after cast removal, such as complex regional pain syndrome type I or carpal tunnel syndrome.

Measurement of Variables

After cast removal, each patient underwent a radiological evaluation to assess the results of the orthopedic reduction. Consisting of simple and standardized radiographs in 2 planes; the posterior-anterior view was performed with the patient at 90° of arm abduction, with 90° elbow flexion, and wrist in pronation, thus ensuring that in the radiological image the ulnar sulcus of the extensor carpi ulnaris muscle is radially at the styloid ulnar.³⁰ In the case of the “true” lateral view, this was performed with the patient arm adducted against the trunk, elbow flexed 90°, forearm held in neutral rotation (no pronation or supination), and the wrist in neutral position (no radial or ulnar deviation, and no palmar or dorsal flexion). The third metacarpal shaft is parallel to the long axis of the radius.²⁹

According to the Kreder et al standardized technique,²⁶ the orthopedic surgeon measured the following radiological parameters: radial inclination (normal: 21°-25°), radial height (normal: 10-13 mm), volar tilt (normal: 7°-15°), ulnar variance (normal: 0.7-1.5 mm), and articular step-off (normal: 0-1 mm).¹³ Based on the study published by Grewal and MacDermid,¹⁸ alignment was considered acceptable if the residual dorsal angulation was ≤10°, radial inclination was ≥15°, and radial shortening with positive ulnar variance was <3 mm.

Functional evaluations were performed immediately after cast removal and at the 6-month follow-up. The Disabilities of the Arm, Shoulder and Hand (DASH) outcome measure was used to evaluate upper extremity function²⁰; the Patient-Rated Wrist Evaluation (PRWE) was used to evaluate wrist/hand function³¹; and the visual analog scale (VAS) was used to measure pain intensity.³⁵ The assessment were performed by a physical therapist not associated with the research team, with a master’s degree in orthopedic manual therapy and more than 15 years of clinical experience.

Statistical Analysis

All data collected were entered into an Excel spreadsheet for tabulation. Statistical analysis was performed using Stata 11.0 software. Quantitative variables are presented as mean and standard deviation and the qualitative variables as number and percentage. The Spearman coefficient was used to determine the correlation between DRF alignment, evaluated according to radiological criteria, and functional results, evaluated using the VAS scale and DASH and PRWE questionnaires.

Results

The demographic and baseline characteristics of the study group are shown in Table 1. The age range was 60 to 75 years, with a mean age of 68.8 (SD = 8.2). Of the total group, 80.6% of the patients were women, and 70% of the patients were affected on their dominant arm. All patients were treated with closed fracture reduction and plaster casting. The mean length of immobilization was 6.4 weeks. In terms of the subtype of extra-articular fracture, according to the AO classifications, 71.7% of patients presented with an A3 DRF (n = 129), 23.3% with an A2 DRF (n = 42), and the remaining 5% with an A1 DRF (n = 9).

Table 1.

Baseline Characteristics of Patients Older Than 60 Years of Age With Extra-articular DRF.

Characteristic	Patients with DRF (n = 180)
Gender: female, n (%)	145 (80.6)
Age (years), mean (SD)	68.8 (8.2)
Immobilization time (weeks), mean (SD)	6.4 (0.8)
Fracture dominant hand, n (%)	126 (70)
DRF A1 according to AO, n (%)	9 (5)
DRF A2 according to AO, n(%)	42 (23.3)
DRF A3 according to AO, n (%)	129 (71.7)
Radial inclination angle (degrees), mean (SD)	13.9 (3.9)
Radial height (mm), mean (SD)	3.8 (2.2)
Volar tilt (degrees), mean (SD)	−5.2 (12.4)
Ulnar variance (mm), mean (SD)	2.3 (3.5)
Articular step-off (mm), mean (SD)	0.8 (0.5)
Acceptable alignment of DRF,a n (%)	68 (37.8)

Note. DRF = distal radius fracture.

^aResidual dorsal angulation ≤10°; radial inclination ≥15°; and the radial shortening with a positive ulnar variance < 3 mm.

The radiological studies indicated a mean radial inclination of 13.9° (SD = 3.9); mean radial height of 3.8 mm (SD = 2.2); mean volar tilt of −5.2° (SD = 12.4), which indicates a residual dorsal angulation; mean radial shortening of 2.3 mm to ulnar variance (SD = 3.5); and mean articular step-off of 0.8 mm (SD = 0.5). Of the total group, only 68 patients (37.8%) showed acceptable DRF alignment, according to the criteria proposed by Grewal and MacDermid.¹⁸

The results of the functional evaluations are shown in Table 2. After cast removal, the mean DASH score was 70.8 points (SD = 6.50); mean PRWE was 68.3 points (SD = 9.1); and mean VAS 5.9 cm (SD = 1.1). At 6-month follow-up, mean DASH dropped to 32.6 points (SD = 8.4), mean PRWE to 24.2 points (SD = 10.1); and mean VAS to 1.4 cm (SD = 0.9). In terms of the relationship between DRF alignment and functional outcome immediately after cast removal, the correlations were as following: DASH 0.071 (P = .546); PRWE 0.03 (P = .823), and VAS 0.12 (P = .631). At 6-month follow-up, the correlations between alignment and outcomes were as follows: DASH 0.029 (P = .768); PRWE 0.014 (P = .895); and VAS 0.09 (P = .614). These Spearman correlation coefficient values indicate little or no correlation between alignment and outcomes, and the P values were all greater than .05, indicating that the relationships are not statistically significant.

Table 2.

Correlation Between Acceptable Alignment and Functional Outcomes in Patients Older Than 60 Years of Age With Extra-articular DRF According to AO Classification.

Scale	Mean (SD)	Correlation with acceptable alignmenta	P value
DASH initial (0-100 points)	70.8 (6.5)	0.071	.546
DASH at 6 months (0-100 points)	32.6 (8.4)	0.029	.768
PRWE initial (0-100 points)	68.3 (9.1)	0.03	.823
PRWE at 6 months (0-100 points)	24.2 (10.1)	0.014	.895
VAS initial (0-10 cm)	5.9 (1.1)	0.12	.631
VAS at 6 months (0-10 cm)	1.4 (0.9)	0.09	.614

Note. DRF = distal radius fracture; DASH = Disabilities of the Arm, Shoulder and Hand; PRWE = Patient-Rated Wrist Evaluation; VAS = visual analog scale.

^aSpearman correlation coefficient was used.

Discussion

The present investigation evaluated the correlation between the acceptable fracture alignment of fracture based on radiological parameters, and short- and medium-term functional outcome, in patients older than 60 years of age with extra-articular DRF treated conservatively with closed reduction and plaster cast immobilization. There are several published articles on the influence of radiological parameters on clinical outcomes in patients with DRF; the conclusions of these reports are controversial, as some studies suggest that functional outcomes depend directly on anatomical results,^{2,4,16,27,36,39} while other studies indicate that functional outcomes are independent of the residual deformity.^{3,5,6,9,10,15,17,18,21,23,37,41,42}

There are several methodological considerations that could explain the discrepancies, including variability in the sample sizes and follow-up times, and different methodologies for measuring results and performing statistical analysis. However, one of the most important factors is patient selection. Unlike many published articles, we included only extra-articular DRF; this selection criterion helps to ensure that the clinical condition studied is as homogeneous as possible and that variability related to injury complexity does not influence the results.

Another important issue is age. Several authors have proposed a cutoff value for patients of 60 years to provide a differentiated analysis of therapeutic interventions in this age group. The negative anatomical results associated with conservative treatment involving closed reduction and plaster cast immobilization do not necessarily translate into negative functional outcomes in this population.^{3,5,6,9-11,14,15,17-19,21,23,37,41,42} The lack of association between radiological and functional results may be related to lower functional demands on the upper extremity in this age group.^3,6 The discrepancy between “form and function” has been attributed to a lack of highly powered studies employing standardized outcome measures while controlling for confounding variables such a fracture type, age, criteria used to define DRF displacement, and radiologic parameters and ranges of values that define acceptable fracture reduction.^13,25,28 Another important factor is the lack of standardized radiographic measures; authors such as Kreder et al have attempted to establish normative guidelines for radiographic measurements following DRF.²⁶ However, it is unclear if standardized approaches for taking radiographic measures are consistently being used or even if there is consistent interpretation of these radiographic measures.²⁸

Many articles have studied the relationship between anatomical and functional results in older patients with conservatively managed DRF. The following retrospective studies in particular have provided relevant findings suggestive of the conclusion that functional and radiological outcomes are independent in this population. Young and Rayan⁴² found that after a mean follow-up period of 34 months, functional outcomes, personal satisfaction, and return to activities were independent of radiological outcomes in DRF. Chang et al¹⁰ also found that radiological outcomes are unrelated to functional outcomes at 24 months after DRF. Fujii et al¹⁷ concluded that radiological parameters are not associated with function after a mean period of 24 months after DRF. Anzarut et al³ reported that after a mean follow-up period of 6 months, acceptable reduction is unrelated with function. Barton et al⁶ concluded that secondary radial shortening after DRF is unrelated to function using the PRWE score. Jaremko et al²¹ found no relationship between DASH score and acceptable DRF reduction, after a mean follow-up period of 6 months. Grewal and MacDermid¹⁸ concluded that after a mean follow-up of 1 year, poor functional outcomes were not associated with poor alignment. A study by Synn et al⁴¹ showed no a relationship between a displaced DRF and function. Bentohami et al⁹ concluded that after a mean follow-up of 36 months, an unacceptable DRF reduction is unrelated to functional outcome. Finally, Nelson et al³⁷ concluded that after a mean follow-up of 36 months, unacceptable DRF reduction does not affect functional outcomes.

One of the main limitations of our study was the use of a simple or bivariate correlation. We only addressed the influence of radiological parameters on functional outcome and did not consider other variables that might have affected the results. Another methodological limitation is the lack of a universally accepted criterion to define “acceptable DRF reduction” and a consensus on the values of the radiological parameters used to define a reduction as acceptable or unacceptable. Despite some methodological differences, the main results of our study are consistent with those of similar studies in literature; despite poor results in terms of fracture alignment in this group of elderly patients with conservatively managed DRF, especially for residual dorsal angulation and radial shortening, there was no correlation between “acceptable alignment” and short- or medium-term functional outcome as assessed using VAS scale and DASH and PRWE questionnaires.