Does Weightbearing Affect Radiographic or Clinical Outcomes in Distal Radius Fractures Treated With Dorsal Bridge Plate Fixation?

Abstract

Background:

Dorsal wrist spanning plate (DWSP) fixation in distal radius fractures (DRFs) has been proposed to allow earlier mobilization in polytraumatized patients by enabling early weightbearing (WB) through the injured wrist. The purpose of this study is to compare radiographic and clinical outcomes in patients who bore weight through the injured wrist within the early postoperative period with patients who did not bear weight.

Methods:

Patients who underwent DWSP fixation at a single institution were retrospectively identified. Patients who bore weight through the injured wrist for purposes of assisted ambulation (WB) were identified and compared with patients who did not bear weight through the injured wrist (non-weightbearing [NWB]). Outcomes included complication rates, radiographic measurements, visual analogue scale (VAS) pain scores, and range of motion.

Results:

In total, 123 patients underwent DWSP fixation for DRF between 2005 and 2018, including 30 in the WB cohort and 93 in the NWB cohort. There was no significant difference in patient age, sex, or injury to dominant extremity. The WB group had longer duration of DWSP before removal (121 ± 26.2 vs 106.3 ± 29.5 days, P = .02). There was no significant difference in complication rates (13.3% vs 16.1%, P = .71), clinical outcomes (VAS, flexion, extension, pronosupination), or radiographic parameters preoperatively, postoperatively, after plate removal, or at final follow-up.

Conclusions:

Early WB through the injured wrist appears to be safe in patients with DRFs treated with DWSP. There were no significant differences in outcomes or complications between patients treated with DWSP based on WB status postoperatively.

Level of Evidence:

Retrospective cohort, Level III

Introduction

Distal radius fractures (DRFs) account for nearly 17% of all fractures treated in the emergency department with an incidence of approximately 640 000 fractures per year in the United States. ¹ There is a wide array of treatment options for these injuries, including closed reduction and casting, percutaneous pinning, wrist spanning external fixation, volar locked plating, fragment-specific plate fixation, and dorsal wrist spanning plate (DWSP) fixation. The DWSP, also referred to as a bridge plate, provides an effective treatment option for patients with highly comminuted intra-articular fractures and fractures with meta-diaphyseal extension.^1,2 Dorsal wrist spanning plate fixation may also enable weightbearing (WB) through the injured extremity to aid in early mobilization of polytraumatized patients or patients who require upper extremity assisted WB at baseline.^{2 -4} In the DWSP technique, a bridge plate is placed through small incisions over the dorsal radius and hand deep to the extensor tendons resting between the metacarpals and the distal 1/3 of the radial shaft. The plate is then fixed to the second or third metacarpal and radius with traction applied across the wrist, thereby providing ligamentotaxis as well as a dorsal buttress to prevent fracture displacement. If indicated, additional fixation may also be used to improve fracture reduction and fixation. The DWSP is removed in a planned second surgery after the fracture has healed, typically around 3 months after placement.

Clinical series of DWSP for DRF vary widely regarding the time to crutch-assisted WB, with several studies recommending immediate WB and others recommending limiting patients to platform WB until fracture healing.^{5 -9} Biomechanical studies of various bridge plate constructs have demonstrated conflicting results.^2,4 One study of a dorsal shear fracture model stabilized with a DWSP to the second metacarpal found that the DWSP failed consistently in a model of crutch WB. ² Furthermore, a recent cadaveric study demonstrated the axial load to failure in DWSP was less than what is required for crutch ambulation, suggesting that patients should not be allowed to bear full weight using crutches immediately after bridge plating. ¹⁰ In contrast, another biomechanical study found that a DWSP placed either to the second or third metacarpal was stable to cyclic loads up to 300 N, ⁴ which is the approximate maximal axial force with crutch-assisted WB. ¹¹ Furthermore, Ilyas et al ¹² found axial load to failure in DWSP with central holes and DWSP without central holes to be 240 and 398 N, respectively. The sole clinical study in the literature, a retrospective case series of 11 patients, found that patients who immediately bore weight through a DWSP did not experience nonunion or unplanned reoperations. However, 2 patients had implant breakage at the middle holes, presumably due to fatigue failure, requiring hardware removal earlier than planned. ³

The purpose of this study is to compare the functional and radiographic outcomes of patients with a DRF with concomitant lower extremity injuries who bore weight through a DWSP with a similar cohort who did not bear weight through a DWSP. We hypothesized that patients allowed to bear weight through the DWSP would have similar radiographic and clinical outcomes without an increase in complications compared with patients who did not bear weight through the DWSP.

Materials and Methods

Patients

We retrospectively identified all patients who underwent DWSP for DRF at a tertiary care center within a single institution between 2005 and 2018 (Figure 1). Exclusion criteria included concomitant injury to the ipsilateral upper extremity or prior history of fracture or surgery to the ipsilateral upper extremity. Baseline patient and injury characteristics were recorded from the electronic medical record, including demographic information, hand dominance, date of injury, concomitant injuries, date of index surgery, and tobacco use status. Implant details were recorded from the operative note. Weightbearing status in the immediate postoperative period was identified through review of postoperative notes by the operative team and/or by the physical therapist. Patients who used an unmodified assistive device such as standard walker, crutches, or a broad-based cane within 2 weeks of the surgery were classified as WB. Patients who did not bear weight through the injured wrist or exclusively used a modified assistive device such as a platform walker were classified as non-weightbearing (NWB). The primary outcomes were clinical and radiographic outcomes, including visual analogue scale (VAS) pain scores, wrist range of motion, and radiographic parameters (radial height, radial inclination, and volar tilt). Secondary outcomes included complication rates and reoperation rates.

Figure 1.

Preoperative (a) posteroanterior and (b) lateral radiographs of a patient with highly comminuted distal radius fracture.

Radiographic measurements were made using films immediately following the index surgery, immediately after removal of the bridge plate and at final follow-up. Radiographic measurements included radial height, radial inclination, and volar tilt. Wrist range of motion and VAS score were recorded at final follow-up appointment. Any complications and additional surgeries beyond the planned DWSP removal surgery were noted. Nonunion was defined as absence of bridging callus at the fracture site on radiographs at 6 months. Malunion was defined as dorsal tilt >10°, radial inclination <10°, and radial shortening >3 mm.^13,14 Institutional review board approval was obtained and data were collected according to the approved protocols.

Surgical Technique

Patients in this series were treated with DWSP according to a previously described surgical technique. ⁵ Plates were affixed to either the third metacarpal using a 3-incision technique or the second metacarpal using a 2-incision technique. The 3-incision technique uses incisions made over the third metacarpal, the dorsal distal radius, and the distal 1/3 of the radial shaft. The extensor pollicis longus tendon is transposed and the floor of the fourth compartment is elevated through the central incision. The bridge plate is passed from the distal incision to the proximal exposure beneath the fourth extensor compartment contents. The plate is fixed to the third metacarpal and the fracture is reduced with a combination of manual traction, supination, and ulnar deviation while a serrated clamp secures the plate to the radial shaft. The plate is then fixed proximally after visual confirmation that there is no extensor tendon entrapment or limitation to passive digital flexion and radiographic confirmation of fracture reduction. Plates used in this series included a 3.5-mm dynamic compression plate (Synthes, West Chester, Pennsylvania), a 2.4/2.7-mm DWSP with central screw cluster (Synthes), a 2.7/3.2-mm DWSP without central screw cluster (TriMed Valencia, Santa Clarita, California), or a 2.7/3.5-mm DWSP precountoured DWSP with central screw cluster (Acumed, Hillsboro, Oregon) (Figure 2). The plate is removed after fracture consolidation and wrist range of motion is initiated thereafter. All surgeries were performed by 4 fellowship-trained hand surgeons.

Figure 2.

Intraoperative (a) posteroanterior and (b) lateral fluoroscopy images of dorsal bridge plate fixation.

Statistical Analysis

Patient characteristics, radiographic and clinical outcomes, and complications rates were compared across cohorts using with t tests for continuous variables and χ² analysis or Fisher exact test as appropriate for categorical variables. A significance level of P <.05 was used for all comparisons. We then conducted a noninferiority analysis comparing complication rates between the WB and NWB cohorts. A noninferiority margin of 10% was selected based on clinical judgment, and the 95% confidence interval (CI) for the absolute risk difference was calculated. All statistical analyses were performed using Stata/MP 13 (StataCorp, College Station, Texas).

Results

Patient Characteristics

We identified 123 patients meeting inclusion criteria who underwent DWSP fixation for DRFs between 2005 and 2018. Of these, 30 bore weight through the injured wrist in the early postoperative period (within 2 weeks) to use an assistive device for ambulation (n = 22 ambulated with a walker or broad-based cane and n = 8 with crutches). All patients in the WB cohort were polytraumatized patients with concomitant lower extremity injuries. The remaining 93 patients did not bear weight through the injured upper extremity in the early postoperative period and were included in the NWB cohort. Patient demographics and characteristics are included in Table 1.

Table 1.

Patient Demographics.

Characteristic	NWB (n = 93)	WB (n = 30)	P value a
Mean age, y	59.2 (SD = 17.0) 18-89	56.8 (SD = 21.1) 17-92	.53
Female, No. (%)	55 (59.1)	16 (53.3)	.58
RHD, No. (%)	71 (76.3)	18 (60.0)	.08
Injured dominant arm, No. (%)	50 (53.8)	13 (43.3)	.32
Polytrauma, No. (%)	24 (25.8)	30 (100)	<.001
Tobacco use, No. (%)	17 (18.3)	3 (10.0)	.40
Additional fixation			.62
None	57 (61.3%)	19 (63.3%)
Volar plate	13 (14.0%)	7 (23.3%)
Fragment-specific	5 (5.4%)	1 (3.3%)
Radial styloid wire/screw	8 (8.6%)	1 (3.3%)
Metacarpal fixation, No. (%)			.25
2nd Metacarpal	4 (4.3)	0 (0)
3rd Metacarpal	89 (95.7)	30 (100)
Central screw cluster fixation, No. (%)	51 (54.8)	16 (53.3)	.89
Mean duration of BP, d	106.3 (SD = 29.5) 56-211	121.2 (SD = 26.2) 81-181	.02
Mean duration of follow-up after index surgery; mo	17.4 (SD = 23.3) 3.3-117.0	10.7 (SD = 6.5) 4.2-36.1	.12
Mean duration of follow-up after BP removal; mo	13.8 (SD = 23.0) 0.4-112.7	6.7 (SD = 6.4) 1.4-31.8	.10

Note. NWB = non-weightbearing; WB = weightbearing; RHD = right hand dominant; BP = bridge plate.

^aχ² and Fisher exact tests were used to compare categorical variables; t test was used to compare continuous variables.

The mean age of patients in the WB cohort was 56.8 ± 21.1 years compared with 59.2 ± 16.9 years for the NWB cohort (P = .53). Females comprised n = 16 (53%) of patients in the WB cohort compared with n = 55 (59%) of patients in the NWB cohort. The dominant arm was injured in n = 13 (43%) of patients in the WB cohort and n = 50 (54%) of patients in the NWB cohort. The bridge plate was affixed to the third metacarpal in n = 89 (96.7%) of patients in the NWB cohort and n = 30 (100%) of patients in the WB cohort. There were 9 patients (30%) in the WB cohort who underwent additional fixation at the time of index surgery, including 7 with volar locking plates, 1 with a fragment-specific plate, and 1 with a radial styloid screw. There were 28 patients (30%) in the NWB cohort who underwent additional fixation at the time of index surgery, including 13 with volar locking plates, 5 with fragment-specific plates, 8 with radial styloid pins or screws, and 2 patients who had a volar locking plate and radial styloid pins or screws.

Outcomes

The DWSP was removed at a mean of 106.41 ± 29.5 days in the NWB cohort compared with 121.2 ± 26.2 days in the WB cohort (P = .02). Final follow-up for the entire cohort was at a mean 15.8 months (range = 3.3-117.0) after the index surgery and 12.1 months (range = 0.4-112.7) after bridge plate removal. Mean final follow-up for the NWB cohort was 17.4 ± 23.3 months (3.3-117.0) after the index surgery compared with 10.7 ± 6.5 months (4.2-36.1) in the WB cohort (P = .12).

There were no significant differences in clinical outcomes at final follow-up (Table 2). Mean VAS pain score at final follow-up was 1.81 ± 2.19 for the NWB cohort and 1.72 ± 2.02 for the WB cohort (P = .88). Mean wrist extension at final follow-up in the NWB cohort was 48.1° ± 21.3° compared with 44.7° ± 21.9° extension in the WB cohort (P = 45). Mean wrist flexion in the NWB cohort was 43.4° ± 20.0° compared with 46.4° ± 19.4° in the WB cohort (P = .47). Supination was 77.4° ± 19.5° in the NWB cohort compared with 79.6° ± 18.6° in the WB cohort (P =.61). Pronation was 80.8° ± 16.1° in the NWB cohort compared with 84.3° ± 8.4° in the WB cohort (P =.29).

Table 2.

Clinical Outcomes at Final Follow-up.

Outcome	n	NWB (n = 93)	n	WB (n = 30)	P value a
VAS (mean ± SD)	58	1.8 ± 2.2	18	1.7 ± 1.0	.88
Extension (mean ± SD)	92	48.1 ± 21.3	30	44.7 ± 21.9	.45
Flexion (mean ± SD)	92	43.4 ± 20.0	30	46.4 ± 19.4	.47
Supination (mean ± SD)	81	77.4 ± 19.5	27	79.6 ± 18.6	.61
Pronation (mean ± SD)	81	80.8 ± 16.2	27	84.3 ± 8.4	.29

Note. NWB = non-weightbearing; WB = weightbearing; VAS = visual analogue scale.

^at test was used to compare continuous variables.

There were no significant differences in radiographic outcomes (radial inclination, radial height, volar tilt, intra-articular step-off) across the cohorts at any time point including after the index surgery, following bridge plate removal, and at final follow-up (Table 3) (Figure 3).

Table 3.

Radiographic Outcomes After Index Injury, After Removal of Bridge Plate, and at Final Follow-up.

Radiographic outcome	n	NWB (n = 93)	n	WB (n = 30)	P value a
After index
RI (mean ± SD)	84	17.5 ± 5.1	28	19.6 ± 5.3	.06
RH (mean ± SD)	70	9.2 ± 3.3	26	1032 ± 2.7	.11
VT (mean ± SD)	83	2.0 ± 7.1	28	2.0 ± 8.2	.97
After ROH
RI (mean ± SD)	75	16.7 ± 5.5	25	19.2 ± 6.0	.08
RH (mean ± SD)	32	9.3 ± 2.9	10	11.2 ± 1.6	.10
VT (mean ± SD)	74	2.2 ± 6.7	24	0.5 ± 8.4	.31
Final follow-up
RI (mean ± SD)	59	16.1 ± 7.3	21	17.6 ± 5.9	.39
RH (mean ± SD)	59	9.2 ± 3.9	21	10.1 ± 3.3	.37
VT (mean ± SD)	59	3.0 ± 10.6	21	−0.4 ± 6.6	.19

Note. NWB = non-weightbearing; WB = weightbearing; RI = radial inclination; RH = radial height; VT = volar tilt.

^at test was used to compare continuous variables.

Figure 3.

Postoperative (a) posteroanterior and (b) lateral radiographs 3 months following bridge plate removal demonstrating fracture healing in satisfactory alignment.

Complications and Reoperations

In total, there were 19 complications (15.5%) in 15 patients and 12 reoperations (9.8%) occurring both prior to and following bridge plate removal. In the NWB cohort, there were 15 complications (16.1%) in 12 patients, including nonunion (3), malunion (2), painful hardware (2), wrist contracture (1), finger stiffness (1), distal radioulnar joint (DRUJ) instability (1), infection (1), failure of bridge plate construct (distal screw pullout and third metacarpal fracture) (1), delayed carpal tunnel syndrome (1), post-traumatic arthritis (1), and refracture of the radial column (1). The complication rate was 13.3% in the WB cohort and 16.1% in the NWB cohort, with an absolute risk difference of −2.8%. The 95% CI for this difference was −14.2% to 8.6%. As the upper limit of the CI did not exceed the prespecified 10% non-inferiority margin, WB was deemed noninferior to NWB with respect to complication risk.

There were 9 reoperations (9.7%). In the WB cohort, there were 4 complications (13.3%) in 3 patients, including painful hardware (2), wrist contracture (1), and compartment syndrome (1). There were no cases of hardware failure or infection. No patients had malunion or nonunion. There were 3 reoperations (10.0%), including removal of hardware (volar plate) (2) and fasciotomy for compartment syndrome (1). Full descriptions of complications and reoperations are included in the appendix.

Discussion

Distal radius fractures occur in about 3.5% of polytraumatized patients and DWSP offers the potential to allow WB through the injured wrist to aid in early mobilization.^15,16 The present study provides a comparison of clinical and radiographic outcomes for WB versus NWB cohorts of patients treated with DWSP for DRF. The key finding of this study is that there were no significant differences in complication rates or clinical and radiographic between these 2 cohorts. Our study found that bridge plates were removed an average of 18 days later in the WB group, which was statistically significant but not likely clinically relevant.

The findings of this study are consistent with biomechanical data, suggesting that DWSP are stable under conditions of crutch ambulation.^4,17 Guerrero and colleagues ⁴ demonstrated that precontoured DWSP placed to either the second or third metacarpal with 2.4-mm screws underwent mean displacement <1 mm to cyclic axial loads of greater than 300 N, which is approximately the highest force borne by the wrist during crutch ambulation. The same study additionally found that DWSP placed on the third metacarpal as opposed to the second metacarpal was stiffer in flexion and axial loading. Relative to wrist spanning external fixators, 2.4-mm DWSP has been found to be stiffer in axial load, tension, and lateral bending while evidence is mixed on which is stiffer in flexion/extension.^18,19 Conversely, a recent biomechanical study found that a volar locking plate in a dorsal shear fracture model provided greater stability to axial load than a 2.4-mm dorsal plate placed to the third metacarpal and maintained stability at well above the 300 N threshold that may approximate WB. ² A recent cadaveric study by Raducha et al demonstrated that while DWSP may not reliably withstand full crutch WB forces, they are able to tolerate loads associated with walker-assisted ambulation. Importantly, most patients in our WB cohort used walkers rather than crutches, which likely subjected the implant to lower forces than simulated in full crutch WB models. ¹⁰ These differences may explain why no hardware failures occurred in our WB group despite biomechanical concerns. However, we believe the clinical decision-making between DWSP and volar locking plates should remain individualized based on fracture severity and patient needs, particularly in polytraumatized individuals requiring early WB. Currently, there is limited evidence that directly compare outcomes of early WB between DWSP and volar plate constructs, and further research is needed to clarify if one method is superior for this indication.

While the present study suggests that the DWSP for DRFs enable early wrist WB, there are also specific risks to bridge plate placement. Although the DWSP limits early wrist mobilization and stiffness is frequently cited as a potential complication in the literature, this risk appears to be theoretical. Our findings align with a recent systematic review which demonstrated that functional outcomes following DWSP removal are generally favorable, without significant evidence of increased postoperative stiffness. ²⁰ In addition, wrist WB did not appear to increase the risk of wrist stiffness, as final range of motion did not significantly differ between the WB and NWB groups. Moreover, range of motion outcomes in both cohorts were comparable to previously published results for patients treated with DWSP. There is also a theoretical risk of hardware failure from cyclical loading through a bridge plate. ¹² However, our study did not have any cases of hardware failure in the WB group, suggesting that patients who bare weight postoperatively may not be at high risk. Interestingly, this study did find one case of hardware failure in the NWB group, with failure at the site of distal fixation with screw pullout at the third metacarpal.

Our study has limitations inherent in its retrospective, nonrandomized nature. It is unknown to what extent these 2 cohorts are comparable due to the possible influence of early WB as an indication for DWSP fixation. Thus, in the WB group, it is possible that bridge plate fixation was used for less severe injuries that may have received volar plate fixation or nonoperative treatment in a non-polytraumatized patient. In addition, auxiliary fixation methods (eg, styloid pins, screws) were used in many cases. While DWSP was the primary fixation method, the outcomes are not purely from the DWSP, but rather from the entire construct that was chosen to address the unique features of each individual injury. Furthermore, DWSP fixation was to the third metacarpal in all but 4 patients, and therefore, these findings may not be directly applicable to cases where DWSP is fixated to the second metacarpal. This cohort represents a trauma population from a large geographical area, which contributed to limited patient-reported outcome and follow-up data for comparison between the 2 cohorts. In addition, due to the heterogeneous population and the retrospective design, postoperative therapy protocols were not standardized, as access to therapy varied based on patients’ concomitant injuries, rehabilitation needs, and access to care. Last, bridge plates were removed once radiographic evidence of fracture healing was observed. However, as no current guidelines exist regarding the optimal timing for bridge plate removal, the timing of patient follow-up and plate removal likely varied according to surgeon preference. Specifically, the intervals at which surgeons performed follow-up radiographs to assess healing may have differed based on individual practices and patient-specific factors, including injury severity, clinical progression, pain levels, and the patient’s ability to attend follow-up appointments.

In conclusion, this retrospective cohort study showed no significant differences in complications, clinical, or radiographic outcomes between patients with DRFs treated with DWSP who participated in early WB postoperatively. Our findings support the concept that DWSP may safely allow early weightbearing through the injured wrist when fixated to the third metacarpal. Future studies should assess the effect of early WB on patient-reported outcomes and evaluate how patient-reported outcomes compare with treatment with volar plating versus nonoperative treatment.

Appendix

In the NWB cohort, 1 patient was found to have nonunion of the radial column 6 months after the index procedure requiring placement of a radial column screw at the time of bridge plate removal. This patient later developed symptomatic hardware, a prominent distal ulna, and limited supination 7 months after bridge plate removal and underwent removal of radial styloid hardware and Darrach procedure with pain relief and evidence of interval healing 2 months postoperatively. Of the other 2 patients with nonunion, 1 chose nonoperative management and later went on to healing without intervention and 1 underwent bone grafting with revision bridge plating. One patient experienced failure of the bridge plate construct at 11 weeks (distal screw pullout and third metacarpal fracture) and underwent removal of hardware. At time of implant removal, the DRF was found to be at clinical union and additional hardware was not placed. Of the 2 patients with malunion, 1 patient developed post-traumatic arthritis and underwent a wrist fusion 10 months after the index procedure and 1 patient opted to undergo dorsal rim osteoplasty 11 months after the index procedure. There was 1 patient who developed symptomatic DRUJ instability and underwent subsequent DRUJ reconstruction 9 months after index procedure. One patient had refracture through the radial column with fragment shifting identified radiographically 8 weeks after bridge plate removal that was treated with short arm casting for 4 weeks. The fracture healed; however, the patient developed hardware irritation 8 months later and required removal of volar plate. One patient required extensor tenosynovectomy for digit stiffness, 1 patient required dorsal capsulorrhaphy for wrist capsular contracture with limited wrist flexion, 1 patient developed surgical site infection requiring 2 operations for irrigation and debridement prior to bridge plate removal (3 weeks after index procedure), and 1 patient underwent a carpal tunnel release for acute carpal tunnel syndrome 1 week after the index procedure with complete resolution of symptoms.

In the WB cohort, the fasciotomy patient developed forearm compartment syndrome 1 day postoperatively following bridge plate placement requiring decompression fasciotomy with subsequent primary closure. One patient required removal of volar plate 6 months following bridge plate removal due to painful hardware. Another patient required removal of volar plate 9 months following bridge plate removal due to painful hardware and wrist contracture. They also underwent contracture release at that time. There were no cases of hardware failure or infection. No patients had malunion or nonunion.