We wondered whether this fragment specific fracture fixation system would offer an alternative method of treating distal radius fractures. Specifically we asked whether fragment-specific fixation could achieve early return to normal activities, functional range of motion and early return of grip strength and whether the results would be reproducible between two cohorts in differing institutions.
MATERIALS AND METHODS
We retrospectively reviewed two groups of patients at different facilities and several years apart to add support for our results being reproducible. Both groups had the same implants. One group (Group 1) included the first 20 patients with 20 intraarticular distal radius fractures treated with the TriMed® fixation system from November 1998 to March 2000 at the University of Southern California. The second group of 17 patients was treated in an institution in Lund, Sweden from September 2003 to December 2004.
In Group 1, many of the fractures involved high-energy mechanisms and had a high degree of comminution. Two patients were excluded leaving 18 for study. One patient presented with a distal radius malunion and underwent corrective osteotomy with the TriMed® system. Another patient presented with an intra-articular distal radius fracture and originally was treated with external fixation. This patient had an inadequate reduction and had definitive ORIF with the TriMed® system. The remaining 18 patients had an average of 32 years (range, 19-55 years). There were 10 men and eight women. Fifteen patients sustained the fracture through a fall, and three patients were injured in motor vehicle accidents. One patient had an ipsilateral concomitant injury that was a displaced scaphoid fracture. These 18 patients were observed for an average of 6.5 months (range, 6 weeks-9 months).
All 18 patients met criteria for operative ORIF based on clinical and radiographic examination. All fractures were intraarticular with varying degrees of comminution. Considerable loss of volar tilt (>20° of dorsal angulation), excessive radial shortening (>5 mm), or articular displacement (>2 mm) were indications for operative reduction. Patients were evaluated by emergency room physicians and/or orthopedic residents, had their fractures splinted, and were then evaluated by the orthopaedic hand service for definitive treatment. Seven of the 18 patients initially were treated with attempted closed reduction. The remaining 11 patients had fractures with comminution and articular incongruence. No manipulations were performed preoperatively. The time to operative fixation averaged 8.5 days (range, 3-27 days). Preoperative planning included standard posterior anterior and lateral radiographs. Postoperative immobilization consisted of volar splints placed for 1 week to 3 weeks. All patients were encouraged to perform finger exercises immediately postoperatively. Occupational therapy was implemented for 15 of 18 patients. The other three were scheduled for occupational therapy but did not comply.
Group 2 included 17 patients with 17 intraarticular distal radius fractures treated from September 2003 to December 2004 at the University of Lund using same system (Group 2). Patients were an average of 53 years (range, 36-82 years). Bone supplement Norian SRS® was used in two patients. The time from injury to operation ranged from 2 days to 16 days. These 17 patients were observed for an average of 6 months (range 5 weeks-30 months).
The TriMed® fixation system involves fragment specific fixation system. Because of its specificity in hardware, this system is adaptable to almost all distal radius fracture patterns. All procedures were performed with fluoroscopic imaging and general anesthesia. All fractures were approached through a two-incision exposure. The initial part of the exposure involves a volar approach to the wrist between the flexor carpi radialis and the radial artery. The first dorsal compartment is identified while carefully protecting the radial artery and superficial radial nerve braches. The first dorsal extensor compartment is then incised (leaving the distal 0.5-1 cm of the extensor retinaculum of the first dorsal extensor compartment intact if desired), and the abductor pollicis longus and extensor pollicis brevis tendons are mobilized. The bare spot on the distal most aspect of the radial styloid just dorsal to these tendons is identified. To facilitate mobilization of the radial column fragment, the brachioradialis muscle can be released from its insertion on the distal radius. A preliminary reduction is performed and an initial 0.045 K-wire is driven from the bare spot of the radial styloid obliquely through the radial styloid fragment and into the radial shaft. Optimally, this K-wire should exit the radial shaft in the interosseous space. One should avoid a dorsal or volar exit because the pin could irritate the tendons and leave little room for the subsequent fixation. The dorsal fragments then are addressed through a longitudinal dorsal incision initially centered at Lister's tubercle by dissecting between the third and fourth dorsal compartments. Inspection of the fragments may determine which components will be used for fixation. The presence of a dorsoulnar fragment warrants fixation of that fragment with the specifically contoured dorsoulnar pin plate that uses two 0.045 K-wires and 2.4-mm cortical screws to secure fixation. If there are small dorsal cortical fragments, small wire forms and buttress pins can be used to provide stability for the small fragments without inducing further comminution to the small fragments. Bone substitute with autogenous or allograft also can be used.
After securing the dorsal components of the fracture the radial styloid fragment and column are secured with the radial column pin plate. This is secured underneath the tendons of the first dorsal compartment. The radial pin plate is placed over the initially placed K-wire, and the plate is secured to the radial shaft using 2.4-mm screws. This securely fixes the reduced radial column to the shaft. The plate follows the contour of the radius and its flare, giving rigid fixation with a low profile and minimal surrounding soft tissue irritation. A second 0.045 K-wire is placed through a remaining distal pinhole in the plate. These K-wires (as with the ones used for the dorsoulnar pin plate) are cut and bent using a specialized three-point bending pliers to allow impaction, and the cut end is impacted into a remaining hole of the plate. Volar rim fragments may occur in isolation or part of the fracture of several fragments. Large fragments of articular surfaces can be stabilized with the volar buttress plate. These plates also are low in profile and usually can be placed through the same volar incision by reflecting the pronator quadratus muscle. Smaller fragments also can be addressed using the wire forms including the more recently developed ulnar buttress pin that is helpful in addressing the volar ulnar intra-articular fragments (Figs 3-5).
Patients were immobilized with a short-arm plaster splint for 5 days to almost 4 weeks (the duration of the plaster splint decreased as confidence in the system increased). After that time a removable splint was used for 2 to 4 more weeks, and range of motion exercises were begun but giving the patient the option of using the protective splint for daily activities if desired. In Group 1, earlier patients were immobilized for 3 weeks to 3.5 weeks, the patients at the latter part of study were only immobilized for 2 weeks.
We determined time of return of function and return to daily activities or employment. A clinical examination was performed to determine the presence of skeletal deformities, evidence of nonunion, or irritation from the fixation. For Group 1 range of motion and grip strength of the affected wrist were measured by an orthopaedic resident, hand fellow, or faculty member. The range of motion measurements and grip strength were recorded at 1 month, 3 months, and 6 months and available for all 18 patients. In group 2, the complete data for range of motion and grip strength were available for 14 of the 17 patients.
In Group 1, the average time required returning to normal activities or regular employment was 6 weeks (range, 3-16 weeks). The duration of time between surgery and return to employment was the time before preoperative work duties and not modified work duties. Two patients had a prolonged period of convalescence because of multiple associated injuries.
None of the 18 patients in Group 1 had wrist or forearm deformities. After 6 weeks no patient had pain at the fracture site. There was no evidence of loss of fixation 6 weeks postoperatively.
At 6 months postoperatively the average wrist extension was 55° (range, 20-70°), the average wrist flexion was 52° (range, 20-70°), the average supination was 52° (range, 30-70°), and the average pronation was 58° (range, 30-75°). Grip strength was recorded with three successive measurements with a Jamar® dynamometer (Preston, Jackson, MI).
We identified no intraoperative complication. Of the 18 patients, two had minor postoperative hardware complications. One patient had persistent dorsal wrist pain that was localized to the region of the dorsal ulnar pin plate. This plate was removed 6 months after the original surgery with resolution of symptoms. The second patient began developing pain at the volar wrist region 9 months postoperatively, which led to the removal of the L volar plate after 1 year.
In Group 2, the average grip strength was 67% of the uninjured extremity (range, 31-100%). The average wrist flexion was 45° (range, 30-80°), the average wrist extension was 52° (range, 30-80°), the average pronation was 80° (45-90°), and the average supination was 73° (45- 90°) (Table 1). Radiographic assessment showed excellent restoration of joint congruity, volar tilt, and ulnar variance. At surgery the initial correction of volar tilt averaged 22° (as measured from the initial dorsal displacement), joint congruity was restored to 1.8 mm, and ulnar variance to 2 mm. At final followup there was only a 2° loss of the initial correction of the dorsal angulation, no loss of joint congruity, and 0.3 mm of change in ulnar variance.
Comparison of range of motion at 6-month followup demonstrated similar results with the exception of pronation supination (Table 1). According to the work of Brumfield5 all ranges and grip strengths allow for activities of daily living.
We present one patient (Patient 1) from Group 1 with a distal radius fracture. The patient was a construction worker who fell 10 feet and sustained a distal radius fracture. No other injuries were incurred. After having ORIF with this fragment-specific system he returned to work 6 weeks postoperatively (Fig 6). This shows that solid fixation and ability to return to strenuous activity has been accomplished by fragment-specific fixation.
In order to evaluate the possible advantages of newer concept of internal fixation using small fragment specific implants (Trimed® system) in allowing patients early return to daily activities and restoration of a functional range of motion we focused our study on two groups of patients treated several years apart and at separate institutions to document these parameters and the reproducibility of good results by different surgical groups.
Limitations of this study include restricted followup and two separate cohorts evaluated and treated by separate groups of medical personnel. Group 1 patients were treated between 1998 and 2000 and represented the initial use of the fragment specific fixation system, while Group 2 patients were treated between 2003 and 2005 at a different institution by surgeons with greater experience with the system. Both groups however, had a followup average of about 6 months. Absolute comparisons cannot be made because the surgeons had different periods of time to become familiar with the system. However, patients in both groups obtained range of motion that is within parameters needed for activities of daily living.5
Optimum treatment for distal radius fractures still is unknown and achieving consistently good outcomes for intraarticular distal radius fractures remains a surgical challenge. Maintaining articular congruency is important in preventing radiocarpal osteoarthritis with subsequent loss of motion and pain.4,8,9,11,13-15,27
Two components for achieving successful treatment of these types of fractures are meeting radiographic criteria for acceptable reduction, joint congruity, and radiographic parameters, and maintaining reduction until solid union has been achieved. This enables the patient to return to their preinjury functional status.
There have been many methods for stabilizing distal radius fractures. Casting and immobilization have been used for treating extraarticular Colles' fractures, but they are not the primary choice for treating intraarticular fractures of the distal radius.1-3
The method of treating fractures as a result of a high energy impact with soft tissue damage has evolved from plaster to pins to various plating techniques.8,9,11,14,15,17,22 As noted earlier although there have been numerous classification systems to describe the distal radius fractures, integrating classification systems into treatment plans could be helpful but has not been effective, perhaps because of difficulty in interobserver reliability in classifying fractures.2 Although the classification systems identify many separate fragments in distal radius fractures, prior plate fixation of these fractures depended on a single plate and or stand alone K-wires.
Intraarticular fractures of the distal radius have inherent difficulties such as higher degrees of comminution, small fragments, poor metaphyseal support after impaction, and associated extensive soft tissue injury.1,6,9 Because the fractures involve multiple fragments, addressing these pieces individually may have benefits in more accurate reduction and stable fixation of the fragments.
The TriMed® system is based on fragment specific ORIF principles. Rather than using a specific classification system intra-articular distal radius fractures are interpreted as having four or five major cortical fracture components based on standard posteroanterior and lateral radiographs. Fracture fixation follows several principles: (1) screw fixation usually is reserved for the proximal bone cortex where the thickness allows for adequate purchase; (2) fixation of distal components is based on the strong bone of the ipsilateral radial shaft proximal; (3) shortening of the distal radius from cancellous bone impaction may require grafting for support minimizing collapse; (4) hardware should allow for gliding motion of tendons; (5) exposure should cause minimal disruption to adjacent soft tissue structures; (6) fracture fragments must be manipulated with controlled technique and (7) stability of fixation to allow early range of motion. These are the principles that the TriMed® system applies.
Based on our data, which has shown the ability of fragment-specific fixation systems to provide stable fixation and early return to daily activities, fragment-specific fixation seems to be a reasonable treatment alternative for a difficult fracture.10,17 Our postoperative immobilization protocol shortened as confidence was building in this fixation system. Immobilization was provided by a simple volar wrist splint for 5 to 7 days in patients treated after the study group was compiled. All patients regardless of immobilization time had a successful nontender bony union.
Two of the 18 patients required removal of a component of the fixation. One patient with a very petite wrist eventually had a volar L plate removed, and another patient had a dorsal ulnar plate removed. Both patients had resolution of their symptoms. Intraoperative findings did not reveal obvious tenosynovitis in either patient.
Despite these two minor complications in the initial series of Group 1 patients, the promising results for both groups using TriMed® system addresses the important aspects of treating complex distal radius fractures. These include anatomic fixation that is fragment specific and rigid fixation allowing for early motion.
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