Our institutional review board approved this study. All patients older than sixty-five years who had an acute distal radial fracture were considered for inclusion. The inclusion criterion was unacceptable fracture alignment after one attempt at closed reduction. Unacceptable closed reduction was defined as dorsal angulation of >10°, volar angulation of >20°, an articular gap or step-off of >2 mm, radial inclination of <10°, or radial shortening of >5 mm. The exclusion criteria were a preexisting severe illness, a previous wrist injury, a surgical delay of more than two weeks, and a concomitant ulnar neck fracture.
Between March 2007 and October 2008, forty-eight patients (fifty distal radial fractures) were recruited for this study. There were forty female patients (83%) and eight male patients (17%) with a mean age of seventy-three years (range, sixty-five to eighty-nine years). Twenty-nine fractures (58%) were in the right wrist, and twenty-one (42%) were in the left wrist.
Of the fifty fractures, forty-two (84%) resulted from a fall from a standing height. The other eight (16%) resulted from a high-energy injury: three (6%) were caused by a fall from a height above the level of the head, and five (10%) were sustained in a motor-vehicle accident. Twenty-three fractures (46%) involved the ulnar styloid. Two fractures were classified as grade-I open fractures according to the Gustilo and Anderson classification system9.
Distal radial fractures were classified with use of the Orthopaedic Trauma Association Fracture Classification10. Two of the authors (J.K.K. and Y.D.K.) classified all fractures, and disagreements were settled by consensus. There were twenty A3 fractures, three B3 fractures, five C1 fractures, eighteen C2 fractures, and four C3 fractures (Table I).
Study Protocol
The surgical procedures were performed by one surgeon (J.K.K.) after patient randomization. A permutated block randomization method was adopted with blocks of four allocations. Each block contained two allocations of volar locking plate fixation alone (Group 1) and two allocations of volar locking plate fixation plus injection of calcium phosphate bone cement (Group 2). A computerized random-number generator was used to formulate an allocation schedule. The randomization scheme was generated with a web site11 by an independent research assistant.
Methods of Treatment
Group 1 (Volar Locking Plate Fixation)
Twenty-five distal radial fractures (Group 1) were stabilized with volar locking plate fixation alone. The distal radial fractures were reduced with use of a volar approach and were stabilized with a 3.5-mm (until June 2007) or 2.4-mm (after July 2007) volar locking compression plate (Synthes, Paoli, Pennsylvania).
Group 2 (Volar Locking Plate Fixation Plus Injection of Calcium Phosphate Bone Cement)
Twenty-five distal radial fractures (Group 2) were stabilized with volar locking plate fixation with the addition of an injection of calcium phosphate bone cement. The calcium phosphate bone cement powder (Calcibon; Biomet Merck, Darmstadt, Germany) consisted of 61% a-tricalcium phosphate, 26% calcium hydrogen phosphate (CaHPO4), 10% calcium carbonate (CaCO3), and 3% precipitated hydroxyapatite. The cement is prepared by mixing the cement powder with cement liquid (a 4% aqueous solution of disodium hydrogen phosphate [Na2HPO4]). The surgical exposure and plate types were the same as those used in Group 1, as described above.
Calcium phosphate bone cement was injected through cortical defects on the radial side of the distal radial fracture, while metaphyseal defects were directly visualized. Soft tissues were visualized on both the radial and the ulnar side of the distal part of the radius during injection of the cement to allow direct visualization of extraosseous cement extrusion and to prevent contact between the cement and the surrounding soft tissues.
Postoperative Management
Postoperative management was the same for the two groups. A short arm splint was applied and worn for two weeks. During weeks two through four, a removable short arm brace was used but was removed for active wrist motion exercises.
Outcome Measurement
Patients were assessed clinically and radiographically during the early postoperative period and three and twelve months postoperatively. Forty-seven distal radial fractures (twenty-three [92%] of those in Group 1 and twenty-four [96%] of those in Group 2) were available for follow-up at three months, and forty-one cases (twenty [80%] of those in Group 1 and twenty-one [84%] of those in Group 2) were available at twelve months (Fig. 1).
A flow diagram according to the CONSORT (Consolidated Standards of Reporting Trials) guidelines. CPC = calcium phosphate bone cement.
Clinical Evaluation
Assessment was performed independently by a trained physiotherapist who was unaware of the treatment details. Clinical assessments included determination of grip strength, wrist range of motion, subjective wrist pain, modified Mayo wrist scores (MMWS)12, and Disabilities of the Arm, Shoulder and Hand (DASH) scores13. Grip strength was measured with use of a Jamar dynamometer (Sammons Preston, Bolingbrook, Illinois) with the elbow flexed 90° and the forearm in neutral rotation. Values are expressed as the percentage of the strength on the contralateral (uninjured) side. For grip strength calculations, we allowed for 10% greater strength of the dominant hand when the right hand was dominant, but we did not compensate when the left hand was dominant14,15. The wrist and forearm ranges of motion (extension, flexion, supination, and pronation) were measured with use of a handheld goniometer and are expressed as a percentage of the motion on the contralateral side. Wrist pain during daily activity was recorded with use of a visual analog scale (VAS), on which 0 indicated no pain and 10 indicated the most severe pain imaginable. The MMWS was calculated on a 100-point scale, with 100 points representing normal wrist function. The MMWS was based on separate ratings for pain (25 points), range of motion (25 points), grip strength (25 points), and functional status (25 points). The DASH questionnaire consists of thirty items; twenty-one address abilities to perform specified activities, and nine address symptoms. The DASH scores range from 0 to 100 points, with higher scores indicating greater disability.
Complications during follow-up were recorded by the first author (J.K.K.), who was not blinded to the type of treatment.
Radiographic Evaluation
All radiographs were evaluated by two authors (J.K.K. and S.H.K.). Radiographs of the wrists were obtained immediately after surgery and at the one-year follow-up visit. The volumes of metaphyseal defects were estimated from radiographs obtained immediately after surgery. We hypothesized that the metaphyseal defect was a rectangular hexahedron and calculated it by measuring the length and width on the posteroanterior radiograph and the height on the lateral radiograph. The degree of reduction was assessed radiographically by measuring radial inclination, volar angulation, and ulnar variance. Radial inclination and volar angulation were measured with use of the method described by Goldfarb et al.16, and ulnar variance was measured with the method described by Medoff17. A loss of reduction was defined as dorsal angulation of >10°, volar angulation of >20°, an articular gap or step-off of >2 mm, or radial inclination of <10°. We evaluated whether the injected calcium phosphate bone cement was incorporated into host bone on the one-year postoperative radiographs.
Lumbar spine (L2-L4) bone mineral density was measured in all study subjects perioperatively with dual x-ray absorptiometry (Prodigy Advance; GE Healthcare, Madison, Wisconsin).
Sample Size
To detect a minimum difference of 3° in radiographic outcomes and with distal radial fracture reduction status represented with a standard deviation of 3, a 20% loss to follow-up, a type-I error rate of 0.05, and a power of 0.8, twenty-three cases of distal radial fracture were needed per group.
Statistical Analysis
The Mann-Whitney U test was used to evaluate significant differences between the two study groups for continuous variables, and the Fisher exact test was used to evaluate significant differences for categorical variables. All statistical tests were two-sided, and p values of <0.05 were considered significant.
Source of Funding
There was no external funding source for this study. This study was supported by a grant from Ewha Womans University.
Group 1 (volar locking plate fixation alone) and Group 2 (volar locking plate fixation plus calcium phosphate bone cement) were comparable with regard to age, sex, fracture type, injury mechanism, and bone mineral density (Table I).
Table II shows the clinical outcomes in both groups. No significant differences were found between the groups for any clinical parameter (mean range of motion [flexion arc, extension arc, supination arc, and pronation arc], grip strength, VAS scores, MMWS, and DASH scores) at three or twelve months postoperatively.
No significant differences were observed between the two groups with regard to any radiographic parameters in the initial postoperative period or at twelve months postoperatively (Table III). The mean approximate volumes (and standard deviation) of the metaphyseal defects in Groups 1 and 2 were 7.2 ± 2.4 and 7.0 ± 1.9 cm2, respectively, which were not significantly different. All patients (twenty-one fractures) in Group 2 who returned for the twelve-month follow-up visit had radiographic evidence of incorporation of the calcium phosphate bone cement into host bone.
Complications
Loss of reduction occurred in one wrist in each group, and both patients refused a reoperation. Two superficial skin infections developed (one in each group), and both responded to intravenous antibiotics without surgical debridement.
All fractures healed uneventfully. There were no tendon-related complications, and no patient required a second operation.