Volar Plate vs. Conventus DRS Fixation

Open reduction and internal fixation (ORIF) of unstable distal radius fractures is performed using a variety of fixation techniques. The most common method is fixed angle volar plate application. The investigators plan to compare the outcomes of fixed angle volar plating with a novel FDA approved intramedullary fixation device, Conventus DRS.

Distal radius fractures are the most common fractures in the upper extremity. While a widely used method of fracture fixation, numerous studies have shown that locked volar plate fixation is associated with soft tissue irritation, flexor and extensor tendon rupture, and screw penetration of the radiocarpal or the distal radioulnar joint (DRUJ). Prominent hardware mandates hardware removal in 5-18% of cases.

Intramedullary fixation has recently received more attention in the literature because of the minimally invasive procedure required for device implantation. Additionally, because intramedullary fixation places the implant within the bone instead of onto it, the lack of implant exposure, as well as decreased soft tissue dissection, carries the potential for decreased inflammation at the surgical site. This prospective randomized case series will evaluate the clinical and functional outcomes of an expandable intramedullary fixation device and compare the complication profile with traditional fixed angle volar locked plating in a single-surgeon case series at a single hospital.

The wide variety of distal radius fractures demand customized treatment, and a number of different surgical treatments methods are available.(1) While percutaneous/external fixation, dorsal plating, fragment specific fixation, and intramedullary rod fixation have been studied, volar locked plate fixation has emerged over the past decade as the most common and versatile method of fracture fixation. Unfortunately, soft tissue and hardware complications continue to plague volar plate fixation, including digital stiffness, loss of forearm rotation, tendinopathy and tendon rupture, nerve injury and compression, hardware irritation, screw prominence, CRPS, and malunion.

Tarallo et al performed a retrospective review of 303 patients who had undergone volar plate fixation and found that implant-related complications had occurred in 5% of the patients (2). Of these, common complications seen were tendon rupture, screw loosening, and penetration into the articular space. While Tarallo et al studied only hardware related complications, other studies have reported complications associated of volar locking plate fixation as high as 22-27% (3,4). The flexor pollicis longus in particular is vulnerable to rupture, as hardware prominence at the watershed line of the distal radius exposes the FPL and other flexor tendons to frictional forces which result in fraying and rupture (5). Prominent pegs or screws dorsally threaten the extensor pollicis longus and neighboring extensor tendons.

Intramedullary fixation has limited data to date, and the current methods are applicable to a relatively narrow subset of radial fracture types. In a case series of three patients, Gunther and Lynch have shown that intramedullary fixation performed with a partially flexible rod that can be locked into rigid position once implanted in the bone resulted in good functional outcomes (6). Patients returned to their daily lives and at one-year post-operatively no adverse effects were reported. A prospective study analyzing the comparative functional outcomes between intramedullary nail versus volar plate fixation similarly found that functional recovery was comparative between the two groups, and that complication rates were slightly lower in the intramedullary fixation cohort (7). The authors of this study however noted the continued potential for screw penetration into the distal radioulnar joint (DRUJ).

The Conventus DRS expandable intramedullary fixation device used in this proposed study is FDA approved. A cadaveric study compared the fixation strength of the Conventus DRS with fixed angle volar plate fixation and demonstrated equivalency between the two for axial compression mean stiffness and dorsal bend mean stiffness (8). The Conventus DRS has been used in Europe where over 250 patients have been treated with the device. A safety and efficacy 'white paper' of the first 60 patients treated for a wide variety of fractures demonstrated excellent improvements in DASH scores with few hardware related events and an overall adverse event profile of 8.3%. (9) There was one re-operation for loss of fixation and four minor cases of neuritis that resolved. The device is FDA-approved in the US, and is being used across the country.

Eligibility Criteria:
Inclusion Criteria:

* Skeletally mature patients (18-80)
* Unstable AO Type A and C1 fractures
* Closed injuries, acute (\<14 days), displaced, and unstable

Exclusion Criteria:

* Patients under the age of 18 or over the age of 85 (if included in our analysis, these would likely be outliers in our patient population)
* Patients with documented complex regional pain syndrome (CRPS) or history of CRPS
* Patients with suspected or known allergies to titanium or nickel
* Patients who are non-English speakers
* Patients with open wound fractures
* Patients with inflammatory arthritis
* Patients with positive pregnancy test
* Additional musculo-skeletal injuries of the upper extremity would represent exclusion criteria (elbow fractures, scaphoid fractures, and contralateral wrist fracture).
* Previous major wrist injury or surgery (not including Carpal Tunnel, De Quervain's and trigger finger release)
* Patients with previously diagnosed metabolic bone disease, currently being treated.
* Non-English speaking patients (validated, translated questionnaires are not available)
* Patients needing ipsilateral concomitant operations that will have material impact on the study
* Patients with previous wrist fractures, prior wrist injury, stiffness, degenerative joint disease, or pain
* Previous minor surgery - for carpal tunnel, de Quervain's, ganglion, etc. - does not constitute exclusion criteria