Spanning Bridge Plate Fixation of Distal Radial Fractures
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➢ Dorsal spanning bridge plate fixation offers an option for the surgical treatment of distal radial fractures in the setting of metaphyseal bone loss or diaphyseal extension, complex injuries requiring extensive soft-tissue and osseous reconstruction, or severe osteoporosis. It is also a salvage option after distal radial nonunion.
➢ Reduction is performed with use of ligamentotaxis. The plate is fixed from the radial shaft to either the second or third metacarpal, spanning the wrist joint for the duration of fracture-healing, and is removed after fracture consolidation (at approximately 3 months).
➢ Surgical fixation to the second metacarpal may increase the risk of damage to the radial sensory nerve, whereas fixation to the third metacarpal may increase digital extensor tendon friction with the plate.
➢ There is currently no evidence-based recommendation whether to preferentially affix the plate to the second or third metacarpal. Both options may offer advantages based on the fracture pattern.
➢ The functional outcomes and complications associated with this technique are similar to those associated with other methods of fixation of distal radial fractures.
Distal radial fractures constitute approximately 17% of all fractures treated in emergency rooms1,2. The principles of surgical fixation have been well described and include anatomic reduction, stable construct fixation for the duration of fracture-healing, and a treatment plan that allows for the restoration of functional wrist kinematics3-8. Numerous techniques have evolved to treat varying fracture patterns. Open and indirect reduction techniques are utilized with stabilization constructs that include percutaneous pinning, joint-sparing plate fixation, and bridging immobilization with plate or external fixation6,8-13. These options allow the treating surgeon to tailor treatment to fracture characteristics, personal preference, and skill.
Multifragmentary intra-articular distal radial fractures continue to pose a considerable challenge despite the existence of multiple options for treatment. Dorsal spanning plate fixation has been described as a treatment option for these injuries and has been reported to be useful in cases of polytrauma as the construct allows early weight-bearing and transfer in patients with concurrent pelvic and lower-extremity fractures14-16. The plate is temporarily fixed to the second or third metacarpal under the extensor compartment to the radial shaft, bridging the wrist joint for approximately 12 weeks. The plate supplements ligamentotaxis with indirect fracture reduction, provides a dorsal buttress to prevent fracture displacement after reduction, and is removed after fracture-healing has been achieved9,10,14,17,18.
The initial indications for use included unstable comminuted distal radial fractures, bilateral wrist fractures with metaphyseal bone loss or diaphyseal extension, and complex injuries requiring extensive soft-tissue and osseous reconstruction10,14,15,18. More recently, this method has been described for use in the elderly patient population in the setting of osteoporotic fragility fractures and also as a salvage option after distal radial nonunion17,19.
This method of fixation is gaining acceptance; however, some controversies remain with regard to the optimal location of fixation on the second or third metacarpal, theoretical complications associated with tendon adhesions, and concerns regarding functional outcome after immobilization of the joint for the duration of fracture-healing.
The concept of internal distraction plate fixation for the treatment of distal radial fractures was introduced by Burke and Singer almost 2 decades ago to address the complications associated with external fixation, including maintenance of reduction, pin-track infections, and finger stiffness9,20-22. The initial description of the technique involved anatomic reduction and the placement of an AO 3.5-mm stainless steel 9-hole compression-type plate from the radial shaft to the third metacarpal, under the fourth dorsal compartment, with distraction through the wrist joint to prevent articular fracture loading and chondrolysis9. The initial report described the outcomes for a patient 4 years after treatment of an open comminuted intra-articular fracture with this method. The results were excellent, with a flexion-extension arc of 88% and a pronation-supination arc of 99% in comparison with those for the uninjured wrist. Since then, additional studies have evaluated functional outcomes after the use of this method10,17,19,23.
Hanel et al., in 2006, described a modification of this technique that involved the use of a 2.4-mm stainless steel plate that was passed from the second metacarpal under the second compartment14. Screw fixation was secured on the second metacarpal and the dorsoradial aspect of the radial diaphyseal shaft, introducing a concept that stabilization of the wrist in ulnar deviation may provide improved restitution of radial length, radial inclination, and volar tilt of the radial fracture column14,24. The added ulnar deviation may ergonomically assist grip strength and may facilitate the use of ambulatory devices such as crutches or a walker24,25.
Currently, there is no accepted standard with regard to whether the second or third metacarpal is superior for fixation. The advent of volar fixed-angle distal radial plating and fragment-specific fixation greatly expanded the options for the treatment of distal radial fractures; however, there was no evidence to support the use of these options in conjunction with partial weight-bearing in the polytrauma setting6,14. Additional biomechanical research on this technique was conducted in response to a need for a construct that allowed partial weight-bearing through the wrist in the setting of polytrauma and lower-extremity injuries16.
Indications and Contraindications
Since the initial description of this technique, the indications for its use have expanded to include unstable comminuted distal radial fractures, bilateral wrist fractures with metaphyseal bone loss or diaphyseal extension, complex injuries requiring extensive soft-tissue and osseous reconstruction, injuries necessitating early weight-bearing and transfer, dorsal shear fractures, clinically unstable patients, and osteoporotic fragility fractures; the procedure also has been used as a salvage option for the treatment of distal radial nonunion14,16,17,19,24. While the present review focuses on the treatment of distal radial fractures, this technique also has been suggested for the treatment of complex carpal instability and near-complete wrist amputations24. The advantages of dorsal spanning bridge plating include immediate unrestricted use of the hand and immediate partial weight-bearing through the construct to facilitate transfers, self-care, and nursing needs in the setting of polytrauma and lower-extremity injuries. In addition, although the plate does not allow motion across the radiocarpal joint, digital motion and forearm rotation remain unrestricted24.
This procedure is contraindicated for patients with expected poor follow-up, complex injuries prohibiting fixation at the diaphyseal radial shaft and/or metacarpals, palmar lunate facet fractures that do not reduce with ligamentotaxis, and preexisting extensive radiocarpal arthrosis prohibiting salvage of the radiocarpal joint19,24,26. In the latter scenario, primary arthrodesis might be considered.
The original descriptions of this technique involved the use of 12 to 14-hole 3.5-mm AO dynamic compression plates and 2.4-mm titanium mandibular reconstruction plates9,10,18. Since the advent of the technique, newer 2.4, 2.7, and 3.2-mm stainless steel locking plates (Synthes, Trimed) that taper at each end have been designed to facilitate gliding under the extensor compartment and to minimize the displacement of extensor tendons14. For patients with extensive metadiaphyseal extension or bone loss, a 3.5-mm plate may be selected instead24.
The surgical technique involves the use of either the third metacarpal or the second metacarpal for distal fixation9,14,17-19,24. In both variations, the patient is anesthetized and is placed supine with the extremity placed on a radiolucent hand table. Finger traps are donned in a sterile fashion with approximately 4.5 kg of longitudinal traction applied to the wrist through a rope-and-pulley system (Fig. 1). The C-arm fluoroscopy unit is positioned at a 45° angle above or below the hand table to allow space for the surgeon.
Reduction is attempted with the closed maneuver as described by Agee with use of indirect capsular ligamentotaxis13. The maneuver combines longitudinal traction, palmar translation, and pronation of the hand relative to the forearm. If reduction is successful in a closed manner, the plate application then proceeds. If acceptable reduction is not possible, an open approach with supplemental fixation (i.e., fragment-specific fixation, Kirschner wire fixation, or additional plating) may be required. This most frequently occurs when the volar medial corner of the radius remains displaced volarly. In these cases, the volar medial fragment can be fixed with a small volarly based plate.
After reduction and provisional fixation, the plate is positioned over the skin, guided by image intensification (from the radial shaft to either the second or third metacarpal). Markings are placed on the skin to indicate the proximal and distal 4 screws on the plate and serve to guide the placement of each incision. Figure 2 illustrates the surgical technique.
If the second metacarpal is selected for fixation, a 4 to 5-cm incision is made over the metacarpal base and the insertions of the extensor carpi radialis longus (ECRL) on the second metacarpal base and the extensor carpi radialis brevis (ECRB) on the third metacarpal base are identified. A second incision is then made over the radial shaft at the level of the planned plate placement. The location of the second incision is usually just proximal to the outcropping muscle bellies of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB), which are retracted to identify the interval between the ECRL and the ECRB in the proximal incision. The plate can either be advanced distally starting within the proximal incision, or vice versa, with care being taken to avoid extensor tendon impingement14,24.
If the third metacarpal is selected for fixation, a 4 to 5-cm incision is similarly carried out to the base of the third metacarpal. A second incision is positioned just ulnar to the Lister tubercle, and the third compartment is opened to allow extensor pollicis longus (EPL) tendon transposition radial to the tubercle. The extensor tendons in the fourth compartment are then elevated ulnarly to allow plate placement on the floor of this compartment, and a 2-cm segment of the posterior interosseous nerve may be excised to prevent neuroma. A third and final incision is then made on the dorsoradial aspect of the radius, approximately 4 cm proximal to the fracture. The superficial branch of the radial nerve, emerging under the brachioradialis, is identified and protected. An elevator is used to clear a track from the proximal incision to the distal incision in order to allow for unobstructed passage of the plate. The plate is then passed from proximal to distal, with care being taken to ensure that there is no extensor tendon impingement9,10,18,19.
In both cases, plate fixation is carried out with a combination of cortical locking and non-locking screws. The screws are applied while the wrist is distracted with 5 kg of weight, which unloads the wrist and prevents compression across intra-articular fracture fragments. The order and type of screws that are placed facilitate the final fracture-fixation construct. A cortical screw is placed in the distal end of the plate, compressing the plate onto the metacarpal. Similarly, a non-locking screw is placed into 1 of the holes at the proximal end of the plate, compressing the plate to the radius. The second and third screws can be either locking or non-locking. Wolf et al. demonstrated that a stable construct consisted of 2 non-locking screws and 1 locking screw at either end of the plate16. Ginn et al. used an additional 3.5-mm screw that was passed through the central hole of a 3.5-mm bridge plate into subchondral bone to buttress the articular surface of the lunate fossa18. It is our practice to avoid placing bridge plates smaller than 3.5 mm into the fourth extensor compartment because of concern regarding plate fatigue at the radiocarpal joint and the devastating impact that a broken plate would have on extensor tendon integrity.
Prior to closure, the stability of the distal radioulnar joint (DRUJ) is assessed and the joint is fixed if it is found to be unstable. Options for fixation of an unstable DRUJ include triangular fibrocartilage complex (TFCC) repair, reconstruction of the TFCC, or DRUJ reduction and percutaneous fixation with two 1.6-mm (0.063-in) Kirschner wires passed proximal to the joint14. Additionally, bone graft can be placed in the setting of substantial bone loss10. The incisions are closed and dressed in a standard fashion with a long-arm or short-arm splint14,19. We prefer initial mobilization in a long-arm splint with elbow flexion of 90° and forearm supination of 60°.
Variations of postoperative care have been reported, but each focuses on early return of motion, especially supination and pronation9,14,24,26,27. Digital range-of-motion exercises and load-bearing through the forearm and elbow begin immediately10,14,24. The postoperative splint remains in place for 2 weeks and is then transitioned to a removable splint. In patients with lower-extremity injuries, platform-crutch weight-bearing is allowed within the first week postoperatively and is then transitioned to standard handgrip-crutch weight-bearing at 4 to 6 weeks after surgery. Lifting and carrying are restricted to approximately 2.5 to 4.5 kg until fracture-healing has been confirmed10,14.
DRUJ stability and forearm motion are assessed 2 weeks after surgery. If the DRUJ is stable and the patient can achieve full supination without pain, splinting is discontinued. If supplemental fixation with Kirschner wires was performed, the wires are removed at 6 weeks postoperatively. Patients should be followed at routine intervals until plate removal to ensure that there are no complications, such as plate fracture, necessitating revision fixation. The bridge plate is removed with a second-stage procedure once fracture consolidation has been confirmed, typically between 12 and 16 weeks postoperatively14,18.
The ability to use spanning bridge plate fixation with early weight-bearing is derived from the biomechanical strength of the construct. Wolf et al., in a study involving 10 cadaveric specimens, compared the biomechanical stability of dorsal spanning bridge plating with that of clinically effective distal radial external fixation16. In addition, they examined the number of screws needed in the screw-plate construct to achieve adequate performance. Distal radial fractures were simulated with the creation of a 1-cm dorsal wedge osteotomy in all specimens. Bridge plating involved the use of a 2.4-mm locking plate (Synthes) that was fixed with as many as four 14-mm locked screws placed proximally in the radius and as many as three 10-mm locked screws placed distally in the second metacarpal, with the plate applied directly on the bone. External fixation was achieved with 2 pins placed distally in the second metacarpal and 2 pins placed approximately 55 mm proximal to the osteotomy site in the radius, with the fixator placed approximately 15 to 20 mm off of the bone. Measurements with a displacement transducer were taken during the application of flexion and extension loading for both constructs. The authors found that the internal bridge plate construct was significantly more rigid in both flexion (p = 0.006) and extension (p = 0.004) compared with the external-fixation construct, with a mean displacement that was approximately half of that for the external-fixation construct. Wolf et al. recommended the use of 3 screws in the bridge plate construct to confer adequate rigidity during extension loading and concluded that the internal-fixation construct was significantly more rigid than the external-fixation construct, which has been shown to be clinically effective16,28,29.
Concerns with Use
Hesitation to use this technique derives from concerns regarding the recovery of postoperative motion and strength after immobilization of the wrist for the duration of fracture-healing and the development of scar adhesions involving the wrist and digital extensor mechanism resulting from placement of the bridge plate underneath the extensor compartment23. Additionally, distal radial fractures that are treated with non-spanning dorsal plates have been associated with increased extensor tendon irritation27,30-32.
Two recent cadaveric anatomic studies examined the risk of iatrogenic damage to extensor tendons and sensory nerves when using a bridge plate along the second or third metacarpals33,34. Lewis et al. dissected 6 cadaveric specimens (12 arms total) and created unstable distal radial fractures via a volar approach33. They then applied a 2.4-mm dorsal spanning bridge plate to the second metacarpal of 1 wrist of each cadaver, followed by the application of an identical plate to the third metacarpal of the contralateral wrist, which served as a matched control. All specimens were then dissected dorsally to evaluate the position of the plate relative to soft-tissue structures at risk. The authors found that plating to the third metacarpal consistently entrapped the EPL as well as 1 or both of the first-compartment tendons (APL or EPB) in all specimens. In addition, the extensor digitorum communis (EDC) tendons were displaced radially and the extensor retinaculum was split or entrapped in all specimens with use of a 2-incision technique. Plating to the second metacarpal with a 2-incision technique was not associated with tendon or retinacular entrapment. It must be noted that the placement of the plate on the third metacarpal was done with use of only 2 incisions, rather than 3 incisions as described above, which may account for the observed entrapment9,10,18,19. Neither technique caused entrapment of the superficial radial nerve; however, branches of the nerve were found traversing at the level of the second metacarpal shaft and were protected with exposure33.
Similarly, Dahl et al. dissected 12 fresh-frozen cadavers to evaluate anatomic relationships and structures at risk for iatrogenic injury with each method34. They also found that branches of the superficial radial nerve were at risk with exposure of the second metacarpal and came into contact with the dorsal spanning plate when the plate was fixed to the second metacarpal but not the third. The EDC tendon did not contact the plate when the plate was fixed to the second metacarpal; however, an average of 10 cm of EDC tendon came into contact with the plate when the plate was fixed to the third metacarpal. The terminal branch of the posterior interosseous nerve was found below the footprint of the plate in all specimens that received third metacarpal fixation. There was 1 complication (EPL and extensor indicis proprius entrapment) when the plate was fixed to the third metacarpal. No tendon entrapment was noted in association with second metacarpal plating. Third metacarpal plating involved the use of all 3 incisions as originally described9, and second metacarpal plating involved the use of 2 incisions as described by Hanel et al. and others9,10,14. Considerations for each fixation method are outlined in Table I. While both of these studies33,34 highlighted the theoretical risks of tendon adhesions, tendon rupture, and iatrogenic nerve injury, the cadaveric design limited definitive clinical correlation.
Functional Outcomes and Complications
Functional results and complications have been previously reported in association with percutaneous fixation, volar plating, dorsal plating, and external fixation of distal radial fractures8,35-42. The number of reports on dorsal spanning plate fixation for distal radial fractures has been increasing, but these reports have largely been limited to retrospective reviews9,10,14,15,17,19,23,24. A summary of functional outcomes and complications from all known literature is outlined in Table II.
Seven previous studies have investigated functional range-of-motion outcomes following bridge plating (Table II)9,10,14,17,19,23,24. Those studies represent the results for a combined total of only 108 patients. While those preliminary results were in line with the published outcomes associated with other types of fixation, the relative paucity of data limits strength in consensus outcome reporting6,8,12,35-38,40-42.
There have been even fewer reports detailing results in terms of grip strength, extension torque, and patient-reported outcomes. As with range of motion, preliminary reports9,10,14,17,19,23,24 based on Level-IV evidence with intermediate-term follow-up have been promising and are suggestive of favorable recovery; however, larger prospective studies with systematic reporting of outcomes are needed. Intermediate-term results according to the DASH (Disabilities of the Arm, Shoulder and Hand) score have been favorable, with mean scores ranging from 11.5 to 32, indicating relatively low disability following bridge plating10,17,19,23. In addition, almost full recovery of grip and extension strength has been reported after plate removal, especially in patients with dominant-sided wrist injuries23. In a previous report on end-point functional recovery at >1 year after plate removal, it was found that grip and wrist extension strength on the injured side were decreased in comparison with those on the uninjured side23. However, this difference was not upheld when examining dominant and non-dominant wrist injuries independently. Dominant-sided wrist injuries achieved full recovery compared with the uninjured wrist. The authors suggested that rehabilitation and use of the injured wrist could result in nearly complete recovery of wrist motion and strength.
The vast majority of reported outcomes have been related to complications associated with the procedure. Of the potential iatrogenic injuries that have been noted in cadaveric studies33,34, only the following complications have been reported in association with this technique: tendon rupture (ECRL and EPL), long-finger extensor lag, extensor tendon adhesions, digital stiffness, implant failure, persistent wrist pain, infection, delayed wound-healing, transient radial sensory neuritis, complex regional pain syndrome (CRPS), and compromised fracture-healing (malunion/nonunion)9,10,14,15,17,19,23,24,33,34. Pooled data on complications are shown in Table III, which indicates a total complication rate of approximately 15% (46 complications in 303 patients). It must be mentioned that not all of the referenced studies specifically evaluated each complication listed above; thus, the reported complication rates may be understated. The highest complication rates reported in association with this procedure were for postoperative digital stiffness and implant failure. From the published data, it is unclear if stiffness is preferentially associated with plating to either the second or third metacarpal. Previous studies have suggested that plating to the third metacarpal may increase friction between the plate and the extensor tendons as the plate remains in contact with mobile digital extensor tendons in the postoperative period34; however, there have been no systematic comparison investigations that have addressed complications related to plate fixation on the second versus the third metacarpal.
The limitations of reporting pooled complications in this manner include the retrospective nature and Level-IV evidence of all reviewed studies, inconsistency between studies in terms of data collection and reporting, and variation in surgical method. Future prospective studies are needed to delineate the true incidence of and risk factors associated with complications related to bridge plate fixation. However, on the basis of the limited published literature related to this topic, the rates of complications appear to be much lower than those associated with the use of external fixation, which have been reported to be as high as 63%43-48.
Conclusions and Future Directions
Distal radial fractures account for >640,000 injuries annually in the United States, and the incidence of such fractures is increasing49,50. Distraction bridge plate fixation is an option for the treatment of distal radial fractures and may be useful for the proper indications10,14,17. Proponents of this technique have suggested preferential use of a bridge plate in cases in which external fixation would otherwise be considered, citing the high complication rate associated with external fixation14,43-48.
The indications for the use of this method have been discussed above. There may be additional indications other than the treatment of distal radial fractures, including supplemental fixation in the setting of carpal instability and perilunate injuries and limb salvage in the setting of near-complete amputations of the wrist24. Future studies focusing on these areas will be needed to determine the utility of this method in such cases.
The anatomic considerations related to the use of this technique have been well described, and the considerations regarding surgical fixation to either the second or third metacarpal have been reviewed (Table I)15,24,33,34. The benefits of plating to the second metacarpal may include potentially greater grip strength as the hand is placed in slight ulnar deviation, less tendon excursion over the plate, and the potential for improved restitution of radial length, radial inclination, and volar tilt of the radial fracture column14,16,24,25,34. Plating to the third metacarpal may be advantageous in situations which direct visualization of the lunate facet is needed for reduction, bone-grafting is used to fill a defect, or a subchondral buttress screw is needed10,18. Future comparative studies are needed to assess outcomes related to each variation in surgical technique.
Overall, the published literature supports the use of bridge plating and has demonstrated functional outcomes and complication rates similar to those associated with other methods for the treatment of distal radial fractures8,35-42. The reported outcomes related to bridge plate fixation are limited by the Level-IV, non-standardized study designs. Prospective studies performed in a controlled fashion are needed in order to compare the results between bridge plate fixation and other methods for treatment of distal radial fractures. Such studies should include the assessment of functional outcomes (range of motion as well as grip, pinch, and extension strength on both the involved and contralateral sides), patient self-reported outcomes, and complications, specifically with regard to digital stiffness and implant failure.
Investigation performed at the Department of Orthopaedics, University of Washington, Seattle, Washington
Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article.
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