The Choice of Osteosynthesis for Distal Radius Fractures: A Matter of Taste, Fracture Instability, or Patient-Related Factors? A Retrospective Study of Functional Outcome in 346 Distal Radius Fractures Operated With Percutaneous Wires or Volar Plate Fixation

Abstract

Background:

Surgery with volar locking plate (VLP) for distal radius fractures (DRFs) has become dominant over percutaneous Kirschner wire (K-wire) (PKW) fixation. Not many studies have proved advantages of the VLP and the increasing dominance of the VLP is thus not derived from evidence of superiority but influenced by other factors.

Methods:

By retrospectively classifying 346 DRFs treated with either PKW or VLP fixation, according to the Buttazzoni classification system, we aimed to investigate the determining factors for choice of surgical method, and by review of the patients’ medical records, the functional outcome, duration, and frequentness of the rehabilitation period were correlated to Buttazzoni type and surgical method.

Results:

The odds ratio of having volar plate fixation was negatively correlated to age and positively correlated to a higher Buttazzoni type. We found no clinically significant differences in the functional outcome for different Buttazzoni type of fractures within the VLP and PKW groups, respectively, nor between the 2 methods of surgery for any Buttazzoni type of fracture.

Conclusion:

Younger patients and fractures with higher grade of instability were more likely to be treated with VLP than PKW; however, neither fracture instability nor surgical method had any impact on functional outcome.

Introduction

Distal radius fractures (DRFs) are the most common fractures at emergency departments worldwide. ¹ In Sweden alone, there are approximately 20 000 cases per year, ² and in Norrköping, a city with 144 000 inhabitants, 500 patients with DRF are admitted to the emergency department every year. ³ Most DRFs can be treated with plaster cast but approximately 30% are treated with surgery in Sweden. ⁴ Despite the large number of radius fractures treated, there is no conclusive evidence on which treatment is preferable for certain types of DRFs. ⁵ The most common methods of surgery for DRFs are percutaneous fixation with percutaneous Kirschner wire (K-wire) (PKW) or open reduction and volar locking plate (VLP) fixation. ⁵

The Distal Radius Acute Fracture Fixation Trial (DRAFT) study, which included 461 patients with DRF randomized to surgery with VLP or PKW, found no differences regarding functionality or patient experience at 3, 6, or 12 months. The cost of PKW was lower, and the surgery took less time than surgery with VLP.^6,7 At 5-year follow-up, there was still no difference in Patient-Rated Wrist Evaluation or in EuroQol-5 Dimension. ⁸ This result is consistent with a meta-analysis from the Swedish Agency for Health Technology Assessment and Assessment of Social Services ⁵ regarding functionality and patient experience in elderly patients with moderately displaced DRFs.

During the past decade, surgery with VLP has become increasingly dominant over PKW and is now chosen for 80% of the operated DRFs in Sweden, ⁴ despite the ambiguous results in the literature. There are several possible reasons for this: the impact of the VLP industry, preferences of the individual surgeons, local traditions, or possible actual differences in outcome that are not yet proven. Differences in outcome might be neglected because of insensitive measurement methods or the inclination to treat all DRFs as one entity, even though a simple extra-articular fracture is prone to behave differently than a comminuted intra-articular fracture.

Several classification systems are used for DRFs—Frykman, Mayo, and Melone—but all, including the AO classification, have shown poor interobserver and intraobserver reliability ⁹ and do not correlate clearly to choice of treatment nor outcome. The Buttazzoni classification (Table 1) was introduced in 2009 ⁹ as a modification of Older’s classification system for DRFs. ¹⁰ The Buttazzoni classification aims at describing the grade of fracture instability to a greater extent than the AO classification, with prospect to anticipate the risk of fracture collapse, by taking into account the dorsal metaphyseal comminution, intra-articularity, and volar metaphyseal comminution. ⁹ It has shown fair to substantial intraobserver and interobserver agreement, ⁹ and Buttazzoni types 2 and 4 have proven to correspond to a greater risk of dislocation, making the classification system usable in clinical decision-making.

Table 1.

The Buttazzoni Classification for Distal Radius Fractures.

• Buttazzoni 1: Extra-articular distal radius fractures without cortical comminution • Buttazzoni 2: Extra-articular distal radius fractures with metaphyseal comminution of the dorsal cortex. • Buttazzoni 3: Intra-articular (radio-carpal joint) distal radius fractures with or without dorsal metaphyseal comminution. • Buttazzoni 4: Distal radius fractures with metaphyseal comminution of volar cortex regardless of other coexisting fracture lines. • Buttazzoni 0: Distal radius fractures that cannot be classified according to any other criteria; for example, partially intra-articular fractures without metaphyseal involvement such as Chauffeur and Barton fractures

Retrospective classification of all DRFs treated with either PKW or VLP fixation between 2012 and 2016 in Norrköping, according to the Buttazzoni classification system, resulted in a collection of 346 DRFs divided by Buttazzoni type. By correlating Buttazzoni type to choice of surgical method and to functional outcome measurements, we aimed to investigate the following:

• The determining factors for choice of surgical method; and

• How functional outcome is affected by the choice of surgical method for patients with different types of DRF.

Our hypothesis was that the surgeon’s choice of osteosynthesis is correlated to the grade of instability of the DRF and that the grade of instability affects the rehabilitation process and the functional outcome.

Materials and Methods

This is a retrospective study of DRFs treated with surgery with either PKW or VLP fixation at Vrinnevi Hospital, Norrköping, between 2012 and 2016. The study period was ended in 2016, because of a shift in the radiological method used for examination of wrist trauma and because of the succeeding dominance of surgery with VLP after 2016.

All skeletally mature patients above the age of 20 with DRF operated with either PKW or VLP fixation were eligible for inclusion in the study. Patients without prereduction radiographs and patients who, within 30 days, had bilateral DRFs were excluded. Three hundred and fifty-six DRFs were identified, and after exclusion according to the above-listed criteria, 346 DRFs were included and assessed.

Data Collection

Data about the eligible study population were collected from a local electronic health record program, using ICD-code (S52.5), fracture of distal radius, that had surgery with either percutaneous wires (NDJ49/NCJ49) or volar plate fixation (NDJ69/NCJ69) in Norrköping between 2012 and 2016.

Information about injured wrist, dominant hand, age at surgery, date of surgery, surgical technique, occurrence and type of reoperations, number of visits, and date of final visit to the orthopedic surgeon and the occupational therapist, respectively, was collected. In addition, measurements of range of motion (ROM; pronation, supination, extension, and flexion, measured by a goniometer in degrees) and grip strength (measured by a Jamar [G.E. Miller, Yonkers, New York] dynamometer in kilograms) at the final visit to the occupational therapist were documented. The relative grip strength, that is, the difference in grip strength between the uninjured and the injured wrist, was calculated. The occurrence and type of reoperations were also registered.

Prereduction and preoperative plain radiographs, with anteroposterior and lateral views, were anonymized and stored in a password-protected archive in PACS (picture archiving and communication system). The plain radiographs were evaluated and classified according to the Buttazzoni classification system (Table 1).

Surgical Treatments

• Percutaneous wires: 2 to 4 wires were introduced through the skin to the fracture gap on the dorsal and radial aspect of the radius, by hand, according to the Kapandji technique. ¹¹ The wires were used for anatomical reduction and were fastened, by machine, at the opposing cortex.

• VLP: Surgery was performed through a modified Henry approach for open reduction and plate application. The plate was attached to the volar aspect of the radius by fixed-angle screws in the distal part of the plate and nonlocking screws in the shaft.

Postoperative Regimen and Occupational Therapy

All patients were offered guided rehabilitation with an occupational therapist specialized in hand surgery. The postoperative regimen and rehabilitation process followed 2 different tracks depending on the method of surgery (Table 2). The occupational therapist decided when the patient’s wrist function was sufficiently rehabilitated and then terminated the treatment. The individual patients’ need for rehabilitation determined the duration and intensity of occupational therapy and is therefore a measurement of the degree of difficulty of the rehabilitation process. Three occupational therapists, working closely together, treated all of the patients.

Table 2.

Postoperative Regimen for Surgery of Distal Radius Fractures With Percutaneous Wires and Volar Locking Plate, Respectively.

Post-op time	Percutaneous wires	Volar locking plate
2 wk	Removal of sutures Change of plaster cast	Removal of sutures Removal of plaster cast Wrist orthosis provided for continuous use Mobility training performed 6 times/d
5-6 wk	Removal of K-wires Removal of plaster cast Wrist orthosis provided for use during sleep and activities Mobility training performed 6 times/d	Wrist orthosis for use during sleep and activities

Note. K-wires = Kirschner wires.

Statistical Analysis

The data were visually inspected in a scatter dot plot for the assessment of normal distribution of the variables. For normally distributed variables, the independent-samples t test was performed. For non-normally distributed variables, a median test was performed. Linear regression was used to examine the effects of the individual factors, gender, age, and surgical techniques, on the functional outcomes.

Fisher exact test was used to compare Buttazzoni classifications with methods of surgery and to investigate whether fracture instability correlates to the choice of osteosynthesis. Fisher exact test was also used to compare Buttazzoni classification with gender and gender with method of surgery.

Analysis of variance was used for comparison of functional outcome in the different Buttazzoni groups.

A logistic regression model was conducted to investigate the effect of the independent variables, age and gender, on the method of surgery. Independent variables were also tested individually in the logistic regression model.

The χ² test was used to investigate whether there was a change regarding fracture complexity (Buttazzoni classification) during the years 2012-2016.

The IBM SPSS Statistics for Mac, Version 26.0, was used for all analyses. P values of <.05 were considered statistically significant.

Results

Demographics

During the study period of 2012-2016, a total of 356 DRFs were eligible for inclusion. Ten patients were excluded because of bilateral fractures within a month (n = 6), missing radiographs (n = 2), and incorrectly categorized fractures (n = 2), and a total of 346 patients with DRF were hence included (Table 3).

Table 3.

Demographics of Patients.

	Percutaneous wire	Volar plate fixation	Total
Surgeries (total)
All	103	243	346
Female	92	188	280
Male	11	55	66
Buttazzoni classification
Buttazzoni 0	1	2	3
Buttazzoni 1	7	1	8
Buttazzoni 2	49	58	107
Buttazzoni 3	23	105	128
Buttazzoni 4	23	77	100

Mean age at the date of surgery was 62.0 years (SD ±13.5) for all patients. The male patients were younger (M = 52.3, SD ±16.3) than the female patients (M = 64.2, SD ±11.7) (P < .001), and a higher proportion of the male patients had surgery with VLP (83.3%) compared with the female patients (67.1%) (P = .011).

The mean age of the PKW group was higher than that of the VLP group (P < .001), suggesting that PKW fixation is more commonly used as a surgical technique in elderly patients.

Fracture Classification and Choice of Surgical Method

In the analysis of Buttazzoni classification and method of surgery, we found that VLP fixation was used more frequently than PKW in surgeries of DRF with a higher Buttazzoni type (P < .001). No differences were found in gender or age distribution among the different Buttazzoni types.

The effect of the variables, gender, age, and Buttazzoni type, on the choice of surgical method was tested individually in a logistic regression model and significant associations for all 3 variables were found. However, in a logistic regression model with all 3 variables, age at surgery, gender, and Buttazzoni classifications, included, gender did not contribute to the model and was subsequently removed. Buttazzoni types 0 and 1 were excluded from the model due to insufficient number of fractures. The predictor variables, age at surgery and Buttazzoni classification, were finally found to contribute to the model. No effects of interaction were observed between the final regressors (Table 4). According to the model, the odds ratio of having volar plate fixation was negatively correlated to age and positively correlated to a higher Buttazzoni type. Thus, elderly patients and fractures without intra-articular involvement or volar comminution were less likely to be treated with VLP fixation.

Table 4.

Prediction Model for Choice of Surgical Method, Using Logistic Regression, Including the Variables Buttazzoni Type and Age at Surgery.

Variable	B	SE	Sig.	Exp(B)
Buttazzoni type 2 (reference variable)			.000
Buttazzoni type 3	1.377	.324	.000	3.963
Buttazzoni type 4	1.122	.327	.001	3.072
Age at surgery	−0.073	.013	.000	0.929

In 2012, surgery with VLP and PKW was approximately equally common; however, in 2016, VLP fixation was the predominant method of surgery (Figure 1).

Figure 1.

Trends in the surgical techniques percutaneous Kirschner wires (blue) and volar locking plate (orange) over the years 2012-2016 in the study population.

A χ² test of independence revealed that there was a significant increase in complexity of fractures during these years (P = .01). Buttazzoni type 4 was almost twice as common in 2014-2016 compared with 2012-2013, whereas Buttazzoni type 2 was slightly less common (Table 5).

Table 5.

Distal Radius Fractures Grouped by Buttazzoni Type During the Years 2012-2016.

			Years					Total
			2012	2013	2014	2015	2016
Buttazzoni classification	2	Count	20	32	18	18	19	107
		Percentage	34	42	33	26	25
	3	Count	29	33	14	23	29	128
		Percentage	49	43	26	33	38
	4	Count	10	11	22	29	28	100
		Percentage	17	15	41	41	37
Total		Count	59	76	54	70	76	335

Functional Outcome

Grip strength and ROM were measured at the final visit to the occupational therapist which occurred at 91 days (median = 91, IQR [interquartile range] = 66) postoperatively for the PKW group and at 85 days (median = 85, IQR = 61) postoperatively for the VLP group (P = .537).

There were no differences in the functional outcome (pronation, supination, extension, flexion, and relative grip strength) for patients with different Buttazzoni types. Analysis of functional outcome measures for the 2 methods of surgery stratified by Buttazzoni type revealed a significant difference only for supination. The group of patients with DRF Buttazzoni 2 operated with VLP showed superior supination (84° [SD ±10], P = .025) compared with those with PKW fixation (78° [SD ±11]); however, in the Buttazzoni type 3 group, the conditions were reversed (wires 86° [SD ±8], volar plate 80° [SD ±12], P = .005).

Within the group with PKW, patients with Buttazzoni type 3 fractures displayed superior supination compared with those with type 2 fractures (P = .009). In the group with VLP fixation, supination was superior for Buttazzoni type 2 patients compared with those with Buttazzoni type 4 fractures (P = .028).

Linear regression analysis revealed significant gender differences in pronation (female, 83° vs male, 80°, P = .014) and relative grip strength (male, 15.9 kg vs female, 9.4 kg, P = .000).

Regarding the rehabilitation process, there was no difference in duration of the occupational therapy (mean VLP, 91 days and PKW, 85 days, P = 0.537), but patients with VLP surgery received, on average, one more visit to the occupational therapist than patients with PKW fixation.

In the PKW group, there were no reoperations registered. In the VLP group, 6 patients had secondary surgery with plate extraction, and in 4 of those cases, synovectomy was performed.

Discussion

The choice of osteosynthesis for DRFs was influenced by the age of the patient and the Buttazzoni type of fracture. Young patients with unstable fractures were to a higher degree treated with VLP fixation.

The preference for VLP fixation in fractures with intra-articular fracture components (ie, Buttazzoni 3), steps, gaps, and need for anatomical reduction is not controversial. In the DRAFFT trial, ⁷ fractures where the joint could not be reduced by indirect means were in fact excluded from the study due to the presumed need for open reduction and VLP fixation. Comminution of the volar cortex (ie, Buttazzoni 4) is considered the strongest risk factor for redislocation in nonsurgically treated DRFs, ¹² and therefore a more stable fixation, such as the VLP, may be preferred. In addition, it is intuitive to use the buttress function of the plate to stabilize a volar comminuted fracture.

We found, however, no clinically significant differences in the functional outcome between DRF Buttazzoni type 2, 3, or 4 surgically treated with VLP versus PKW fixation at the end of the rehabilitation period. There was a statistically significant difference in supination in favor of VLP fixation for Buttazzoni type 2 but the mean difference was only 6°. In the Buttazzoni type 3 group, on the contrary, patients with PKW displayed, on average, 6° superior supination than the VLP group. The statistically significant, but negligible gender difference in pronation between male and female patients can possibly be explained by the greater normal ROM for pronation found in women. ¹³

Although most of the orthopedic surgeons evidently prefer VLP fixation to PKW, not many studies have succeeded to prove any advantages of the VLP.^5,7,14 Our hypothesis was that by subdividing DRFs according to the Buttazzoni type, the advantages of PKW and VLP for each specific fracture type would crystallize out. However, we found no differences in the functional outcome for different Buttazzoni type of fractures within the VLP and PKW groups, respectively, nor between the 2 methods of surgery for any Buttazzoni type of fracture.

Preference for VLP fixation was thus not governed by superior results but rather a conviction that a more complex fracture pattern requires a more stable fixation. Looking at the trends of fracture instability over the years 2012-2016, we found a significantly increased proportion of Buttazzoni type 4 DRFs in 2016 which can possibly partly explain the increased use of VLP. Distal radius fractures are closely related to low bone mineral density,^15,16 and an increased prevalence of osteoporosis ¹⁷ may be the underlying cause of this trend toward increasing fracture instability. Previous studies using the AO classification of DRF^18,19 found no correlation between osteoporosis and fracture complexity. The Buttazzoni classification, with the intention to map instability, may be preferable for correlation to osteoporosis; however, in this study, mean age, correlating to osteoporosis, ¹⁷ did not differ in the different Buttazzoni type groups.

The PKW fixation is sometimes considered a bad choice for osteoporotic bone and for fractures with dorsal comminution because of the lesser stability of the wire fixation compared with VLP fixation. In this study, however, high age was a predisposing factor for PKW surgery and apparently no difference of clinical significance in the functional outcome was found.

A limitation of this study is its retrospective design, which rules out the possibility of including patient-reported outcome measurements. The nonstandardized rehabilitation routine constitutes both a limitation and a possibility. There is no fixed time point for measurements of final functional outcome; however, the duration of the rehabilitation period and the frequency of the visits to the hand therapist act as an indirect measurement of the degree of difficulty of the rehabilitation for each patient.

Conclusion

In conclusion, age and Buttazzoni type influenced the choice of surgical method but neither Buttazzoni type nor surgical method correlated to functional outcome. Although VP fixation was preferred for surgery of more complex fractures, these results suggest that the simpler and cheaper method of PKW fixation should not be abandoned and could be considered for surgery of all Buttazzoni types of DRF.