Radiographic Outcomes following K-Wire Augmentation of Dorsal Spanning Plate Fixation for Intra-Articular Fractures of the Distal Radius

Abstract

Background  Restoration of articular surface alignment is critical in treating intra-articular distal radius fractures. Dorsal spanning plate fixation functions as an internal distraction mechanism and can be advantageous in the setting of highly comminuted fracture patterns, polytrauma patients, and patients with radiocarpal instability. The addition of K-wires to support articular surface reduction potentially augments fracture repair stability.

Questions/Purposes  We examined the radiographic outcomes and maintenance of reduction in patients with comminuted intra-articular distal radius fractures treated with K-wire fixation of articular fragments followed by dorsal spanning plate application.

Patients and Methods  We reviewed 35 consecutive patients with complex intra-articular distal radius fractures treated with dorsal spanning plate and K-wire fixation between April 2016 and October 2019. AO classification was recorded: B1 (3), B3 (2), C2 (2), C3 (28). A two-tailed paired t -test was used to compare findings immediately post-dorsal spanning plate surgery and at final follow-up after dorsal spanning plate removal.

Results  Mean patient age was 43.3 years (19–78 years). Mean follow-up was 7.8 months (SD 4.3 months) from surgery and 2.5 months from pin removal (SD 2.6 months). All patients achieved radiographic union. Radial height (mean interval change (MIC) 0.2 mm, SD 2.2, p  = 0.63), articular step-off (MIC 0.1 mm, SD 0.6 mm, p  = 0.88), and radial inclination (MIC −1.1 degrees, SD 3.7 degrees, p  = 0.10) did not change from post-surgery to final follow-up. Ulnar variance (MIC −0.9 mm, SD 2.0 mm, p  = 0.02) and volar tilt (MIC −1.5 degrees, SD 4.4 degrees, p  = 0.05) were found to have decreased.

Conclusion  Dorsal spanning plate augmented with K-wire fixation for comminuted intra-articular distal radius fractures in polytrauma patients allows for immediate weightbearing and maintains articular surface alignment at radiographic union and may provide better articular restoration than treatment with dorsal spanning plate alone.

Level of Evidence  This is a Level IV , therapeutic study.

Distal radius fractures are one of the most common injuries treated by orthopaedic surgeons. ^{1 2 3} Restoring anatomic length, alignment, rotation, and congruity of the articular surface is critical in treating intra-articular distal radius fractures. Numerous methods including closed reduction, percutaneous fixation, internal fixation, and external fixation have been utilized with varying results. However, there is no consensus on the best-method for treating complex intra-articular distal radius fractures. ^{4 5} A recent meta-analysis of 70 randomized clinical trials involving 4,789 patients demonstrated no clinically important difference between fixation methods for operative management of distal radius fractures. ⁶ In another recent meta-analysis, Wang and Ilyas compared external fixation and dorsal spanning plate fixation in 895 patients over 28 articles.(7) They described lower rates of infections and complex regional pain syndrome in patients who received dorsal spanning plate fixation, with DASH scores and radiographic parameters equivalent between the two groups. ⁷

Certain injury patterns may lend themselves to certain techniques; however, volar locked plating is commonly cited as the preferred method of internal fixation for most distal radius fractures. ⁸ For most fractures, volar plating results in adequate reduction and improved radiographic and clinical outcomes. ⁸ Despite the popularity of volar locked plating, there are some fracture patterns that are not well suited for this technique. Comminuted fractures in polytrauma patients, complex articular fractures, patients with significant radiocarpal instability or bone loss, and injuries involving significant dorsal shearing or comminution typically require more extensive fixation than a standard volar locking plate can provide. Furthermore, volar plating is associated with certain complications, including tendon adhesions, tendon ruptures, symptomatic hardware, loss of articular reduction, and inferior radiographic outcomes for complex fractures. ⁹ In the setting of highly comminuted fracture patterns in polytrauma patients, dorsal spanning plate fixation functions as an internal distraction mechanism and stands out as a promising alternative to volar locking plate fixation. The addition of K-wire fixation to support articular surface reduction potentially augments fracture stability.

The goal of this study is to examine radiographic outcomes of patients with comminuted intra-articular distal radius fractures treated with internal K-wire fixation of articular fragments followed by application of a dorsal spanning plate in patients who may not be amenable to volar locked plating, (e.g., polytrauma patients, highly comminuted articular fractures, and fractures with radiocarpal instability) ( Figs. 1A–C and 2A–C ).

Fig. 1.

Case 1: These are the radiographs of a 34-year-old male multi-trauma patient who sustained an intra-articular distal radius fracture ( A ). He was treated with a dorsal spanning plate augmented with k-wire fixation ( B ). Radiographs obtained at final follow-up demonstrate a healed distal radius with satisfactory anatomical alignment that includes a positive volar tilt ( C ).

Fig. 2.

These are the radiographs of a 38-year-old male who sustained a comminuted intra-articular distal radius fracture with radiocarpal instability and significant bone loss ( A ). He was treated with a dorsal spanning plate augmented with k-wire fixation ( B ). Radiographs obtained at final follow-up demonstrate a healed distal radius with satisfactory anatomical alignment that includes a positive volar tilt ( C ).

Patients and Methods

Institutional Review Board approval was obtained for this study. We reviewed 35 consecutive patients with complex intra-articular distal radius fractures treated with dorsal spanning plate and K-wire fixation between April 2016 and October 2019 by one senior surgeon (SDD). The surgeries were performed using a previously described technique by the senior author. ⁴ The senior surgeon's Level of Expertise (LOE) was determined to be Level V Expert. ^{10 11 12} Demographic data, surgical timelines, and radiographic data were evaluated.

The following information was obtained: sex, age, date of injury, dominant or non-dominant hand, BMI, mechanism of injury, mechanism situation, date of surgery, smoking status, history of prior orthopaedic wrist treatment, post-repair intervals, differences in movement before and after surgery, indication for surgery, age, intraoperative complications, perioperative complications, and follow-up duration. The following radiographic data was measured by a single orthopaedic surgery resident trained by a MSK radiologist at both the time of hardware placement and final follow-up: radial height, radial inclination, ulnar variance, volar tilt, and articular step-off. The number of radiographic values outside acceptable parameters was recorded. We defined acceptable parameters as: radial height >8 mm, radial inclination > 15 degrees, ulnar variance −3 < x <3 mm, volar tilt > − 5 degrees, and articular stepoff <2 mm, consistent with prior studies. ^{5 13 14}

An a-priori power analysis was performed using independent-sample Student's t -tests to determine whether radiographic alignment differed significantly from the time of hardware removal to final radiographic follow-up. A two-sided test with a power of 0.8, significance level of 0.05, and a medium effect size of 0.5 was performed to determine that a sample size of 128 was needed to achieve adequate power. Student's t -test was used to compare continuous variables. All tests were two sided. A value of p <0.05 was considered statistically significant.

Results

Mean patient age was 43.3 years (19–78 years). There were 25 males and 10 females. Average BMI was 27.8 (18.1–35.8, ± 4.2). Five patients reported smoking tobacco. The mechanisms of injury were varied: motor vehicle accident ( n  = 10), fall from standing ( n  = 8), fall from height ( n  = 7. range 5–20 feet), motorcycle accident ( n  = 7), electric scooter accident ( n  = 1), sports injury ( n  = 1), and ballistic injury ( n  = 1; Table 1 ). Mean follow-up was 7.8 months from dorsal spanning plate surgery (3.6–21.7, ± 4.3 months) and 2.5 months from hardware-removal (0–8.8, ± 2.6 months). On average, hardware was removed 5.3 months after dorsal spanning plate surgery (2.3–21.2 ± 4.0 months). 30 of the fractures were closed on presentation and 5 were considered open. AO classification was recorded: B1 (3), B3 (2), C2 (2), C3 (28).

Table 1. Demographics.

Demographics	Number of patients ( n  = 35)
Sex (male)	25
Sex (female)	10
Smoker (yes)	6
Smoker (no)	29
Handedness (right)	33
Handedness (left)	2
Arm injured (right)	19
Arm injured (left)	16
Closed injury	30
Open injury	5

Six patients had associated ligamentous injuries, including four radiocarpal dislocations, one scapholunate ligament injury, and one perilunate dislocation. All patients had K-wires placed at the time of dorsal spanning plate surgery. Three patients underwent concomitant volar locked plating, and one patient underwent simultaneous carpal pinning. In one patient with concomitant 2 ^nd and 3 ^rd metacarpal fractures, the dorsal spanning plate was used to treat simultaneously the wrist fracture and the 2 ^nd metacarpal fracture, while a separate 2.0 mm plate was used for the 3rd metacarpal fracture. One patient was treated with dorsal spanning plate and K-wire fixation, as a revision surgery, secondary to nonunion about five months after undergoing volar locked plating. All K-wires were buried beneath the skin at the time of initial fracture repair. Two patients had prominent K-wires removed six weeks before dorsal spanning plate removal, as their fractures had not yet healed sufficiently to allow for plate removal. All other patients had their dorsal spanning plate and K-wires removed during the same surgery.

Radiographic Outcomes

All patients achieved radiographic union. Immediately after dorsal spanning plate surgery, mean radial height was 11.6 mm (4.2–16.4 ± 2.6 mm), radial inclination was 20.3 degrees (7.0 to 27.0 ± 4.4 degrees), ulnar variance was −0.523 mm (−4.0 to 7.5 ± 2.6 mm), volar tilt was 3.9 degrees (−11.0 to 20.0  ± 7.1 degrees), and articular stepoff was 1.2 mm (0–2.5 ± 0.7 mm). Nine patients (25.7%) had at least one radiographic measurement outside acceptable parameters after dorsal spanning plate surgery (mean 0.34 unacceptable measurements, range 0–3). At final follow-up, mean radial height was 11.5 mm (6.9–16.7 ± 2.5 mm), radial inclination was 21.3 degrees (12.0 to 30.0 ± 4.3 degrees), ulnar variance was 0.34 mm (−4.4 to 8.5 ± 2.5 mm), volar tilt was 5.5 degrees (−12 to 17 ± 6.2 degrees), and articular stepoff was 1.2 mm (0–2.8 ± 0.5 mm). Seven patients (20.0%) had at least one radiographic measurement outside acceptable parameters at final follow-up (mean 0.34 unacceptable measurements, range 0–3) ( Table 2 ).

Table 2. Radiographic parameters.

Radiographic parameter	Average	Range	Standard deviation
Postoperative radial height	11.6 mm	4.2–16.4 mm	2.6 mm
Final follow-up radial height	11.5 mm	6.9–16.7 mm	2.5 mm
Postoperative radial inclination	20.3 degrees	7.0 to 27.0 degrees	4.4 degrees
Final follow-up radial inclination	21.3 degrees	12.0 to 30.0 degrees	4.3 degrees
Postoperative ulnar variance	−0.523 mm	−4.0 to 7.5 mm	2.6 mm
Final follow-up ulnar variance	0.34 mm	−4.4 to 8.5 mm	2.5 mm
Postoperative volar tilt	3.9 degrees	−11.0 to 20.0 degrees	7.1 degrees
Final follow-up volar tilt	5.5 degrees	−12 to 17 degrees	6.2 degrees
Postoperative articular stepoff	1.2 mm	0–2.5 mm	0.7 mm
Final follow-up articular stepoff	1.2 mm	0–2.8 mm	0.5 mm

Note: Radiographic parameters measured immediately postoperatively and at final follow-up for all 35 patients included in the cohort.

Radial height (MIC 0.2 mm, SD 2.2, p  = 0.63), articular step-off (MIC 0.1 mm, SD 0.6 mm, p  = 0.88), and radial inclination (MIC −1.1 degrees, SD 3.7 degrees, p  = 0.10) did not change from post-surgery to final follow-up. Ulnar variance (MIC −0.9 mm, SD 2.0 mm, p  = 0.02) and volar tilt (MIC −1.5 degrees, SD 4.4 degrees, p  = 0.05) were found to have decreased slightly at final follow-up ( Table 3 ).

Table 3. Mean interval change.

Radiographic parameter	Mean interval change (SD)	p -Value
Radial height (mm)	0.2 mm (2.2 mm)	0.63
Radial inclination (degrees)	−1.1 degrees (3.7 degrees)	0.10
Ulnar variance (mm)	−0.9 mm (2.0 mm)	0.02 a
Volar tilt (degrees)	−1.5 degrees (4.4 degrees)	0.05
Articular stepoff (mm)	0.1 mm (0.6 mm)	0.88

^aIndicates statistical significance.

Note: Mean interval change radiographic values measured post-operatively to final follow-up in all 35 patients included in the cohort.

Study Comparisons

In our study, seven of 35 patients (20%) had at least one radiographic value outside acceptable parameters at final follow-up (mean 0.34, range 0–3). In the study by Sharareh and Mitchell, in which K-wires were only used in three patients to supplement dorsal spanning plate surgery, 67% patients had at least one radiographic value outside acceptable parameters (mean 1.38 unacceptable measurements, range 0–4). ⁵ We further compared our results by creating a matched cohort of 24 patients with AO type C3 fractures. This number was selected to be consistent with Sharareh and Mitchell, whose study contained 24 patients. Subjects were matched by AO classification, sex, age, and BMI. A two-tailed t -test was used to compare average radiographic parameters measured at final follow-up in each cohort. The following radiographic parameters were compared: radial height +0.2 mm (11.3 vs. 11.1 mm, p  = 0.98), radial inclination +1.3 degrees (21.0 vs. 19.7 degrees, p  = 0.39), volar tilt +3.5 degrees (4.9 vs. 1.4 degrees, p  = 0.05), ulnar variance −0.49 mm (0.51 vs. 1.0 mm, p  = 0.57) and articular stepoff −0.66 mm (0.74 vs. 1.4 mm, p  = 0.81). Volar tilt was the only parameter found to be significantly higher in our study ( Table 4 ).

Table 4. Study comparisons.

Radiographic parameters ( n  = 24)	Sharareh and Mitchell (SD)	Current study (SD)	p -Value
Radial height (mm)	11.1 mm (3.7 mm)	11.3 mm (2.6 mm)	0.98
Radial inclination (degrees)	19.7 degrees (5.4 degrees)	21.0 degrees (4.2 degrees)	0.39
Ulnar variance (mm)	1.0 mm (2.4 mm)	0.51 mm (0.63 mm)	0.57
Volar tilt (degrees)	1.4 degrees (5.2 degrees)	4.9 degrees (5.6 degrees)	0.05 a
Articular stepoff (mm)	1.4 mm (1.7 mm)	0.7 mm (1.2 mm)	0.81

^aIndicates statistical significance.

Note: Comparison of radiographic values at final-follow up in a subset of 24 patients with AO C3 fractures to a prior study performed by Sharareh and Mitchell.

Complications

In our study, six patients experienced minor complications at a rate of 17.1%; there were no major complications. One patient experienced a 30 degree small finger PIP joint contracture, still present at one year after surgery. Four patients experienced minor but persistent dorsal hand and forearm paresthesias. One patient experienced pin migration through the skin. Zero patients experienced hardware failure or surgical site infection.

Discussion

Prior to the advent of volar locked plating for distal radius fractures, external fixation was commonly used to treat intra-articular distal radius fractures. ¹⁵ External fixation is relatively minimally invasive and avoids soft tissue trauma caused by surgical dissection, open reduction, and plate fixation. ¹⁵ However, external fixation, especially when performed percutaneously, is prone to radial sensory nerve issues. Patient satisfaction and finger mobility with an external frame on the hand and wrist may be decreased during the fracture recovery period. In comparison, dorsal spanning plate fixation is entirely internal and can be placed through the same two incisions generally recommended for external fixation to avoid injury to the radial sensory nerve (at the index metacarpal and the distal one third of the radial shaft).

In both scenarios, articular reduction can be established via distraction and ligamentotaxis. While stand-alone external fixation was initially used with satisfactory results, biomechanical and clinical studies showed further radiographic improvement in fracture alignment when external fixation is augmented with pin fixation. The use of Kirschner wire fixation increases fragment stability and helps prevent loss of reduction. ^{5 15 16 17 18 19} Furthermore, pin fixation results in improved range of motion at final follow-up, consistent with prior studies concluding that optimal anatomic re-alignment is associated with improved functional, radiographic, and clinical outcomes. ^{15 16} Despite good radiographic alignment, external fixation has partially fallen out of favor due to pin site infections, digit stiffness, delays in mobilization, nerve injury, and concerns for malunion or nonunion. ^{9 19 20 21} In a recent meta-analysis, Wang and Ilyas compared external fixation and dorsal bridge plating in 28 articles encompassing 895 patients. They described lower rates of infections and complex regional pain syndrome, with equivalent DASH scores and radiographic parameters between these fixation methods. ⁷

Alternative surgical approaches and techniques are valuable in certain clinical scenarios, especially considering the occasional limitations of volar plating and the complications associated with external fixation. ⁹ Specifically, the authors recommend dorsal spanning plate fixation for highly-comminuted intra-articular distal radius fractures, distal radius fractures in polytrauma patients in which early weightbearing and functional use of the hand is beneficial, distal radius fractures with significant dorsal shearing, radiocarpal instability, and in patients with significant bone loss. As previously mentioned, only certain patient populations with specific injury patterns were eligible for dorsal spanning plate fixation in the present study. The majority of patients (28) had highly comminuted complex intra-articular distal radius fractures which were not amenable to volar locked plating, as determined by the senior author. Seventeen of these patients were polytrauma patients who were non-weightbearing to at least one additional extremity. The remaining seven patients all had significant dorsal shearing, radiocarpal instability, and/or were polytrauma patients who benefited from early weightbearing on the upper extremity (i.e., to use crutches).

The authors do not intend for this paper to make a comparison of internal fixation with volar locking plates. Instead, we are looking to better understand the impact of dorsal spanning plate fixation augmented with K-wire internal fixation compared with dorsal spanning plate fixation alone (using previously published controls). It is indeed true that volar plating could potentially lead to reliable restoration of distal radius anatomy in patients with AO C3 type distal radius fractures; however, it is also true that volar plate fixation with immediate weight bearing as tolerated on the affected hand and wrist in a multitrauma patient may lead to intra-articular screw penetration and loss of fixation. In polytrauma cases, dorsal spanning plate fixation allows patients to weight bear immediately, while also providing satisfactory restoration of radiographic parameters.

Recent studies have shown comparable outcomes between previously described methods and distraction plating to treat complex intra-articular distal radius fractures. ^{4 5 22} Dorsal spanning plate fixation provides rigidity across the fracture site and avoids complications associated with external fixation. ⁴ Huish et al studied radiographic outcomes in 19 patients with complex distal radius fractures who were treated with distraction plating. ²³ The authors utilized additional instrumentation as needed to achieve adequate reduction and fixation, including K-wires in five patients, radial styloid plates in two patients, an additional dorsal buttress plate in one patient, a volar buttress plate in three patients, and a suture anchor to repair the triangular fibrocartilage complex in one patient. ²³ While this paper is different because they specifically included only patients with dorsal marginal impaction and used K-wires in just five patients, they similarly utilized additional instrumentation to achieve fracture reduction and reported satisfactory radiographic results and fracture healing in their study, reporting a 100% union rate. Mean radiographic values were all reported within an acceptable range. One patient had articular step-off greater than 2 mm, and no infections or tendon ruptures were reported. ²³ The results of this study provide evidence supporting the use of additional instrumentation to aid in fracture reduction in patients with complex distal radius fractures. The study evaluated radiographic parameters at final follow-up but did not, however, compare immediate post-fixation reduction films and radiographic values to final follow-up, which we would argue is important to evaluate in considering the effectiveness of dorsal spanning plate fixation in maintaining fracture reduction over time.

A recent study by Sharareh and Mitchell shows good radiographic outcomes for multifragmentary intra-articular distal radius fractures treated with dorsal spanning plate fixation in patients under 65. ⁵ This study, however, utilized pin fixation in addition to distraction plating in only three patients, citing the potential for pin infection and irritation. No other patients received additional instrumentation. Based on previously cited studies discussing the benefits of combining external fixation with Kirschner wires for complex distal radius fractures, it is worth examining the radiographic and clinical results of the combination of dorsal distraction plating and temporary pinning. In theory, this method should improve articular fracture fragment stability, radiographic, and long-term clinical outcomes while still allowing for early mobility of the distal radioulnar joint. The addition of K-wires, however, may increase the postoperative complications such as pin irritation and pin site infection. To avoid pin-site issues, the senior author buries them beneath the skin. Burying K-wires beneath the skin may put patients at slightly increased risk for extensor tendon rupture, however, no patients experienced extensor tendon injury as a result of K-wire fixation in our study. Anecdotally, we have found that the dorsal spanning plate fixation minimizes soft tissue shear around the buried pins making them much less problematic than pins alone about the hand and wrist.

In the study by Sharareh and Mitchell, when looking at dorsal spanning plate fixation without K-wire augmentation, two-thirds of patients demonstrated final follow-up malreduction in at least one radiographic parameter, with an average of 1.4 variables outside of the defined acceptable range. In the present study, 80% of our patients had all radiographic parameters within an acceptable range at final follow-up, versus just 33.3% in the study by Sharareh and Mitchell. ⁵ We postulate that this is due to the use of K-wire fixation to stabilize intra-articular fracture fragments and aid in maintaining fracture reduction.

There are several additional important differences between the present study and the study performed by Sharareh and Mitchell. We included all patients who underwent simultaneous additional instrumentation for the treatment of their distal radius fracture, including three patients with concomitant volar locked plating and one patient with carpal pinning. We view this as a strength of our study, rather than a possible confounding variable, as we believe these additional, fragment-specific interventions help to achieve maximum stability for these complex fractures. While the Sharareh study mentions that all patients maintained articular surface reduction achieved with the use of a dorsal spanning plate, they do not provide mean interval change data in their study. ⁵ By providing this data, we are able to show that distraction plating augmented with K-wire fixation helps maintain articular surface alignment for numerous radiographic variables over time. Interestingly, volar tilt and ulnar variance were found to have decreased marginally from hardware implantation to final follow-up in our study. Large changes in the volar tilt of the articular surface are improbable with a dorsal spanning plate directly on the dorsal surface of the distal radius. However, small decreases in volar tilt and ulnar variance could result from slight settling of the metaphyseal portion of the fracture during bone remodeling and late healing. The more likely explanation, however, is variability in radiographic imaging angles and forearm pronation/supination that may affect the way we measured these parameters, which is certainly an inherent limitation of our study.

Finally, we included all AO classifications in which a dorsal spanning plate was used, highlighting the fact that distraction plating can be applied to multiple patterns of distal radius fractures. It is important to note, however, that the 24 patients we used in the matched comparison cohort all had C3 fractures. This was done to most accurately contrast our results to the study by Sharareh and Mitchell, in which all 24 included patients were classified as C3. ⁵

The present study has several limitations. Since this a retrospective study, there was no matching or randomization performed. The study was conducted without a control or comparison group. In addition, our sample size of 35 was underpowered, making it difficult to draw definitive conclusions from our data. All surgeries were performed by a single surgeon, and functional outcomes were not evaluated. While it is known that restoring radiographic parameters is critical in regaining wrist function and improving functional outcomes, it would also be useful to evaluate functional outcomes such as DASH or Mayo wrist scores. Unfortunately, this is made difficult for many reasons including the retrospective nature of our study, as well as the demographics of our patient population. Our institution is a large and busy county hospital, making it difficult to bring back patients for re-evaluation, as many have incorrect or non-recorded contact information. Additionally, many patients are not local. This is made more difficult by the fact that the majority of our patients do not have health insurance and many may not be able to take time off from work or afford transportation to and from the hospital solely for the purposes of our study.

Another important limitation was the quality of the films used to measure the radiographic parameters. Dorsal spanning plates in initial postoperative films often obscured the radial styloid ( Fig. 2A–C ) and made accurate measurement of parameters challenging. Wrist angulation and pronation/supination of the forearm may have also affected the measurement. Despite these challenges, the single trained observer used a systematic approach to measurement which stayed consistent across patients. The study focused on radiographic examination, and thus clinical outcomes were not evaluated. Finally, we included all consecutive patients who were treated with a dorsal spanning plate at our institution, even those who did not have C3 fractures. While this may decrease the ability to apply our results to all highly complex C3 fractures, we believe it was important to include the other patients to highlight the benefits of dorsal spanning plate use on all patients with intra-articular fractures of the distal radius. It should be noted, however, that the majority of our cohort ( n  = 28) had C3 fractures, and we did perform an additional separate statistical comparison focusing on only this cohort ( Figs. 1A–C and 2A–C ).

Conclusion

In conclusion, the use of a dorsal spanning plate augmented with K-wire fixation for comminuted intra-articular distal radius fractures better maintains articular surface alignment at radiographic union and may provide better articular restoration than treating these complex fractures with dorsal spanning plate alone.