Volar Plate vs. Conventus DRS Fixation

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.

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