Contact stress distributions in malreduced intraarticular distal radius fractures

Reduction Techniques in Volar Locking Plate Fixation of Distal Radius Fractures

Distal radius fractures are the most common upper extremity fracture and volar locking plate fixation has become a common modality for operative management of these injuries over the last 2 decades. However, despite the widespread use of volar locking plates, there remains no comprehensive guide detailing the available reduction techniques using these systems. This review aims to consolidate the reduction techniques from the literature along with the authors' experiences into a blueprint for distal radius fracture reduction when using a volar plate. Techniques described include those with and without use of the plate and with supplementary means of fixation for both extra-articular and intra-articular fracture patterns.

Arthroscopic debridement of the dorsal capsule in intraarticular distal radius fractures: does it provide superior outcomes?

INTRODUCTION

Distal radius fractures (DRFs) are very common. One of the most significant complications after intraarticular DRF is arthrofibrosis with loss of wrist motion and pain. Wrist arthroscopy has become increasingly popular in the treatment of DRF with the advantage of good visualization of the joint surface and soft tissue injuries. In intraarticular DRFs injuries of the dorsal capsule are a characteristic finding which potentially cause loss of wrist motion. In this study, we investigated if arthroscopic debridement of dorsal capsule injuries at time of surgical fixation provides superior outcomes compared to the same treatment without debridement.

MATERIALS AND METHODS

Between 2013 and 2017, we included 42 patients who underwent arthroscopy-assisted palmar plating for intraarticular DRFs in a prospective randomized controlled study. In group A (intervention group), the dorsal capsule tears were debrided during primary surgery, while in group B these were left in place. Active range of motion (AROM), grip strength, subjective outcomes and radiographic results were assessed 3, 6 and 12 months after primary surgery. A subgroup analysis was performed for patient age, fracture severity and duration of immobilization.

RESULTS

Arthroscopic debridement of the dorsal capsule improved AROM in patients over 60 years of age, more severe fractures (AO 23 C2/C3) and prolonged postoperative immobilization for more than two weeks, while it was not relevant for younger patients with simple fractures and short immobilization.

CONCLUSIONS

Debridement of the injured dorsal capsule in arthroscopic-assisted surgical treatment of intraarticular DRFs can improve surgical performance and optimize patient outcomes in a specific subgroup of patients.

Volar versus combined dorsal and volar plate fixation of complex intraarticular distal radius fractures with small dorsoulnar fragment - a biomechanical study

Complex intraarticular distal radius fractures (DRFs), commonly managed with volar locking plates, are challenging. Combined volar and dorsal plating is frequently applied for treatment, however, biomechanical investigations are scant. The aim of this biomechanical study was to investigate volar plating versus double plating in DRFs with different degrees of lunate facet comminution.Thirty artificial radii with simulated AO/OTA 23-C2.1 and C3.1 DRFs, including dorsal defect and lunate facet comminution, were assigned to 3 groups: Group 1 with two equally-sized lunate facet fragments; Group 2 with small dorsal and large volar fragment; Group 3 with three equally-sized fragments. The specimens underwent volar and double locked plating and non-destructive ramped loading in 0° neutral position, 40° flexion and 40° extension.In each tested position, stiffness: (1) did not significantly differ among groups with same fixation method (p ≥ 0.15); (2) increased significantly after supplemental dorsal plating in Group 2 and Group 3 (p ≤ 0.02).Interfragmentary displacements between styloid process and lunate facet in neutral position were below 0.5 mm, being not significantly different among groups and plating techniques (p ≥ 0.63).Following volar plating, angular displacement of the lunate facet to radius shaft was significantly lower in Group 1 versus both Group 2 and Group 3 (p < 0.01). It decreased significantly after supplemental dorsal plating in Group 2 and Group 3 (p < 0.01), but not in Group 1 (p ≥ 0.13), and did not differ significantly among the three groups after double plating (p ≥ 0.74).Comminution of the lunate facet within its dorsal third significantly affected the biomechanical outcomes related to complex intraarticular DRFs treated with volar and double locked plates.Double plating demonstrates superior stability versus volar plating only for lunate facet comminution within its dorsal third. In contrast, volar plating could achieve stability comparable with double plating when the dorsal third of the lunate facet is not separated by the fracture pattern. Both fixation methods indicated achievable absolute stability between the articular fragments.

Origins of the threshold for surgical intervention in intra-articular distal radius fractures

AIMS

The aim of this study was to identify the origin and development of the threshold for surgical intervention, highlight the consequences of residual displacement, and justify the importance of accurate measurement.

METHODS

A systematic review of three databases was performed to establish the origin and adaptations of the threshold, with papers screened and relevant citations reviewed. This search identified papers investigating functional outcome, including presence of arthritis, following injury. Orthopaedic textbooks were reviewed to ensure no earlier mention of the threshold was present.

RESULTS

Knirk and Jupiter (1986) were the first to quantify a threshold, with all their patients developing arthritis with > 2 mm displacement. Some papers have discussed using 1 mm, although 2 mm is most widely reported. Current guidance from the British Society for Surgery of the Hand and a Delphi panel support 2 mm as an appropriate value. Although this paper is still widely cited, the authors published a re-examination of the data showing methodological flaws which is not as widely reported. They claim their conclusions are still relevant today; however, radiological arthritis does not correlate with the clinical presentation. Function following injury has been shown to be equivalent to an uninjured population, with arthritis progressing slowly or not at all. Joint space narrowing has also been shown to often be benign.

CONCLUSION

Knirk and Jupiter originated the threshold value of 2 mm. The lack of correlation between the radiological and clinical presentations warrants further modern investigation. Measurement often varies between observers, calling a threshold concept into question and showing the need for further development in this area. The principle of treatment remains restoration of normal anatomical position. Cite this article: Bone Joint J 2021;103-B(9):1457-1461.

Dorsal fracture-dislocation of the radiocarpal joint: a new classification and implications in surgical treatment

Dorsal dislocations and fracture-dislocations of the radiocarpal joint are a spectrum of pathology involving both the bony and ligamentous structures that stabilize the radiocarpal joint. We retrospectively reviewed 63 dorsal radiocarpal dislocations treated in our Institute in order to propose a new classification and define surgical treatment. Preoperative CT-scan findings together with clinical and radiological outcomes were recorded. We identified four main types of lesions: Type I, pure dorsal radiocarpal dislocation; Type IIA, dorsal wall impaction and radial styloid avulsion; Type IIB, as IIA with additional intra-articular die punch; Type III, volar and dorsal marginal fragments; Type IV, larger volar and dorsal fragments. For each type of lesion, we propose specific options for treatment that are progressively more invasive. We believe that this classification adequately addresses the whole spectrum of bony and soft tissue injuries that occurs in dorsal radiocarpal fracture-dislocations giving a practical guide for surgical treatment.Level of evidence: IV.

Dorsal Lunate Facet Fracture Reduction Using a Bone Reduction Forceps

Background  The dorsal lunate facet fragment represents part of a complex articular injury of the distal radius and is challenging to reduce through a standard volar approach. We propose reduction through a standard volar approach and intraoperative dorsal lunate facet reduction using a bone forceps. To evaluate the postoperative reduction, we used computed tomography (CT) scan. Methods  We retrospectively included 60 patients with a median follow-up of 44 weeks. Fracture reduction was evaluated using pre- and direct postoperative CT scans of the wrist, measuring the articular gap and step of the sigmoid notch. The range of motion was evaluated clinically by the treating physician. Bivariate analysis was performed to compare pre- and postoperative radiographic measurements and to compare wrist range of motion. Results  When comparing the injured with the uninjured wrist, there was a significant difference in flexion, extension, pronation, and supination. In 87% of the patients, there was complete radiographic reduction of the fracture. Conclusion  This study shows that dorsal ulnar lunate facet fracture fragments in distal radius fractures can be reduced through a standard volar approach with the help of an intraoperative bone reduction forceps. Using wrist CT, we showed that 87% of the patients with a dorsal ulnar lunate facet fragment had a postoperative articular step or gap of <1 mm. Level of Evidence : This is a level IV, therapeutic study.

Treatment of intra-articular fracture of distal radius fractures with fluoroscopic only or combined with arthroscopic control: A prospective tomodensitometric comparative study of 40 patients

BACKGROUND

Considering articular distal radius fractures treated with volar plate, we hypothesized that articular radio-carpal displacement was better reduced with arthroscopic control than with only fluoroscopic control.

METHODS

Forty patients with similar articular radius fracture (type C according to AO classification) and high functional needs were treated with volar plate fixation. They were divided in two comparative groups: 20 patients in Fluoroscopic group and 20 patients in Arthroscopic group. Pre and postoperative radiographs and tomodensitometric images were analysed by an independent observer. We evaluate extra and intra-articular displacements according to "Patient Accident Fracture" classification.

RESULTS

We observed a better reduction of the radio-carpal step-off and gap in the arthroscopic group, with a statistically significant difference (p<0.05). The index of postoperative intra-articular reduction was better in the fluoroscopic group (5.5) than in the arthroscopic group (2.2) with a significant difference (p<0.05).

CONCLUSIONS

According to these results, arthroscopy is useful to perform a better articular radio-carpal reduction in distal radius fracture.

LEVEL OF EVIDENCE

Level 3.

The Effect of Displaced Dorsal Rim Fragment in a Distal Radius Fracture

Background In intra-articular fracture of distal radius, the intra-articular fragments can be divided into some specific fragments. In particular, the poor outcomes have been well documented for reduction loss of the volar lunate facet, but the effect of a displaced dorsal rim fracture has rarely been addressed. Materials and Methods The records of 26 patients with dorsal rim fragment displaced by more than 2 mm after volar locking plate (VLP) fixation for a dorsally displaced distal radius fracture (DRF) treated from March 2006 to March 2009 were retrospectively reviewed. Clinical assessments including grip strengths, wrist range of motions, and Disabilities of Arm, Shoulder, and Hand (DASH) scores were performed at 12 months postoperatively. Widths of the distal ends of dorsal rims were determined by preoperative computed tomography (CT). Dorsal rim fragment displacements were measured in immediate postoperative plain lateral radiographs. Radial inclination, volar tilt, and ulnar variance were measured on immediate postoperative wrist radiographs. Arthritic changes of radiocarpal joints were graded using radiographs obtained at 12 months postoperatively. Description of Technique DRFs were fixed using a VLP in the usual manner. Although DRF displacement was noticed after plate fixation, no further procedure was performed. The sizes of articular portions of dorsal rim fragments were measured arthroscopically in 5 of the 26 patients at the time of plate fixation. Results At 12 months postoperatively, mean grip strength, wrist flexion arc, and mean wrist extension arc were 86 ± 13, 87 ± 11, and 91 ± 10%, respectively, of contralateral sides. Mean forearm supination and pronation were 96 ± 8 and 99 ± 5%, respectively, of contralateral sides. Mean DASH score was 11 ± 10 points. Preoperatively, mean width of the distal end of dorsal rim fragments and mean displacements of dorsal rim fragments were 2.0 ± 0.6 and 3.0 ± 0.9 mm, respectively. Mean width of the articular portions of dorsal rim fragment by arthroscopic examination was 1.0 ± 0.4 mm. Mean radial inclination was 21 ± 4.8 degrees, mean volar angulation was 4.8 ± 3.9 degrees, and mean ulnar variance was 0.6 ± 1.8 mm at immediate postoperatively. Two patients showed grade I arthritic changes at 12 months postoperatively. Conclusions The articular portions of dorsal rim fragments measured arthroscopically were smaller than determined by CT. Furthermore, the study shows that displaced dorsal rim fragments in dorsally displaced DRFs treated by VLP do not adversely affect wrist clinical outcomes.

Prospective evaluation of distal radius fractures treated with variable-angle volar locking plates

PURPOSE

To evaluate the radiographic, objective (range of motion and grip strength), and subjective outcomes of variable-angle volar locking plate (VAVLP) fixation for unstable distal radius fractures.

METHODS

Over a 12-month period, we prospectively evaluated 39 consecutive distal radius fractures treated operatively with VAVLPs. Surgical exposure, fracture reduction, plate application, and postoperative rehabilitation were uniformly performed. Clinical outcome and radiographic measures, with a minimum follow-up of 12 months, were obtained.

RESULTS

Final follow-up data were available in 37 patients (26 females and 11 males) with average age of 57 years (range, 16-89 y). The average follow-up time was 14 months (range, 12-22 mo). At final evaluation, average volar tilt was 3°, average radial inclination was 21°, average radial height was 12 mm, and average ulnar variance was -0.2 mm. There was no statistical difference between first postoperative and 1-year follow-up radiographs for any of the measured variables, although there were 4 cases of loss of volar tilt. Average Disabilities of the Arm, Shoulder, and Hand score was 6 and average visual analog scale pain score was 0.3. Mean grip strength at 1 year was 96% of the contralateral side. There was 1 case of variable-angle locking screw loosening and 1 case of extensor tenosynovitis requiring hardware removal. There were no tendon ruptures.

CONCLUSIONS

The VAVLP fixation restored and maintained acceptable reduction in all patients in this series with a complication rate comparable to standard volar fixed-angle locking plates. Treatment of unstable distal radius fractures with a VAVLP resulted in excellent clinical outcomes at 1-year follow-up. However, use of the VAVLP risks soft tissue irritation, hardware failure, and loss of fracture reduction.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The biomechanical effects of a deepened articular cavity during dynamic motion of the wrist joint

BACKGROUND

A deepened articular cavity of the distal radius due to a metaphyseal comminution zone is associated with early osteoarthritis and reduced joint motion. As this deformity has not been investigated biomechanically, the purpose of this study was to evaluate the effects of a deepened articular cavity on contact biomechanics and motion range in a dynamic biomechanical setting.

METHODS

Six fresh frozen cadaver forearms were tested in a force controlled test bench during dynamic flexion and extension and intact mean contact pressure and contact area as well as range of motion were evaluated. Malunion was then simulated and intraarticular as well as motion data were obtained. Intact and malunion data were compared for the scaphoid and lunate facet and the total radial joint surface.

FINDINGS

Due to malunion simulation, cavity depth increased significantly. Motion decreased significantly to 54-69% when compared to the intact state. Malunion simulation led to a significant decrease of contact area in maximum extension for all locations (by ~50%). In maximum flexion and neutral position, contact area decrease was significant for the scaphoid fossa (by 51-54%) and the total radial joint surface (by 47-50%). Contact pressure showed a significant increase in maximum extension in the scaphoid fossa (by 129%).

INTERPRETATION

Already a small cavity increase led to significant alterations in contact biomechanics of the radiocarpal joint and to a significant range of motion decrease. This could be the biomechanical cause for degenerative changes after the investigated type of malunion. We think that restoration of the normal distal radius shape can minimize osteoarthritis risk post trauma and improve radiocarpal motion.

Dynamic versus static external fixation for unstable distal radius fractures: an up-to-date meta-analysis

OBJECTS

Whether dynamic or static external fixation is more appropriate for distal radius fractures is still being debated, our aim is to determine the effect of dynamic versus static external fixation for unstable distal radius fractures in terms of postoperative complication, clinical results and radiological outcomes.

METHODS

We selected PubMed, Cochrane Library, EMBASE, BIOSIS, Ovid and the relevant English orthopaedic journals and pooled data from eligible trials including six eligible randomised controlled trials and two comparative studies containing 998 patients comparing dynamic and static external fixation for unstable distal radius fractures to conduct a sub-group analysis according to different periods of follow-up, aiming to summarise the best available evidence.

RESULTS

The results showed there was an increased risk for pin-track infection in dynamic external fixation group than that in static external fixation group, however, there was the trend of obtaining better clinical effect towards less malunion in dynamic external fixation group, although the results were not statistically significant. With regard to clinical results, range of motion such as extension, supination and pronation were superior in dynamic external fixation group than that in static external fixation group at 6 weeks postoperatively. And there were the trend of obtaining better clinical effect in dynamic external fixation group towards pronation at one year follow-up and grip strength at six weeks, six months and one year follow-up, although no significant differences were viewed. With regard to radiological outcomes, better clinical result was obtained in terms of radial length in dynamic external fixation group immediately after surgery and at six weeks, one year follow-up postoperatively.

CONCLUSIONS

The final results show that there are some evidences supporting the use of dynamic external fixation, which may also have practical advantages over static fixation by allowing earlier limb mobility during the fixation period and enabling such patients to maintain their independence. Limitations remain, a cost-effectiveness analysis and DASH-score assessments at all follow-up evaluations should be more carefully considered and reported in a reliable, consistent and standardised manner.

Management of the distal radioulnar joint and ulnar styloid fracture

Fractures of the distal radius and ulnar styloid have the potential to disturb the normal function of the distal radioulnar joint (DRUJ), resulting in loss of motion, pain, arthritis, or instability. The DRUJ can be adversely affected by several mechanisms, including intra-articular injury with step-off, shortening, and angulation of an extra-articular fracture; injury to the radioulnar ligaments; ulnar styloid avulsion fracture; and injury of secondary soft tissue stabilizers. This article discusses the management of the DRUJ and ulnar styloid fracture in the presence of a distal radius fracture.

Measurement of intraarticular wrist joint biomechanics with a force controlled system

Pathologies of the wrist, such as fractures or instabilities, can lead to alterations in joint biomechanics. Accurate treatment of these pathologies is a frequent challenge for the surgeon. For biomechanical investigations, a test-setup that applies physiological loading of the wrist joint is necessary. A force controlled test-bench with agonistic and antagonistic muscle forces was built to move six fresh frozen human upper extremities through flexion and extension of the wrist joint. Tendon forces, range of motion, intraarticular contact area and contact pressure of the lunate and scaphoid facet as well as tendon excursion were investigated and compared with the current literature. During wrist motion the extensors exerted double the force of the flexors. Capsulotomy and sensor insertion decreased the range of motion from 63.4° (SD 14.1) to 45.9° (SD 23.7). The ratio of force transmitted through the radius and ulna was 77:23 and pressure distribution between the scaphoid and lunate facet showed a 70:30 relationship. The obtained data indicate a good agreement with the available literature. Therefore, the force controlled test-bench in combination with intraarticular radiocarpal measurements can be used to investigate the influence of wrist pathologies on joint biomechanics.

Internal versus external fixation for unstable distal radius fractures: an up-to-date meta-analysis

PURPOSE

Our aim was to compare the effect of internal vs external fixation for unstable distal radius fractures regarding postoperative complications, clinical results and radiological outcomes.

METHODS

We selected PubMed; Cochrane Library; EMBASE; BIOSIS; Ovid and the relevant English orthopaedic journals and pooled data from ten eligible randomised controlled trials containing 738 patients to conduct a subgroup analysis according to different periods of follow-up. Our aim was to summarise the best available evidence.

RESULTS

Results showed that compared with external fixation, internal fixation led to significantly fewer total surgical complications [95% confidence interval (CI) 0.39-0.81, P = 0.002] and reduced the incidence of pin-track infections (95% CI 0.08-0.46, P = 0.0002) after a one year follow-up. For clinical results, grip strength (95% CI 1.59-8.25, P = 0.004), supination (95% CI 13.99-48.83, P = 0.0004) and pronation (95% CI 5.61-26.09, P = 0.002) were superior in the internal fixation group six weeks postoperatively, and the same results were obtained three months postoperatively for grip strength (95% CI 3.21-13.47, P = 0.001) and supination (95% CI 3.61-16.01, P = 0.002). Meanwhile, the Disabilities of the Arm, Shoulder and Hand (DASH) score was superior in the internal fixation group at three months (95% CI -20.62 to -2.07, P = 0.02) and after one year (95% CI -14.37 to -2.32, P = 0.007) follow-up.

CONCLUSIONS

We suggest that the final results are significant and there is some evidence supporting the use of open reduction and internal fixation.

Articular step-off and risk of post-traumatic osteoarthritis. Evidence today

The goal of treatment in intra-articular fractures is to obtain anatomical restoration of the articular surface and stable internal fixation. Studies have attempted to specify how accurately an articular fracture needs to be reduced to minimise the chances of a poor clinical outcome. In this study, the current evidence with regard to articular step-offs and risk of post-traumatic osteoarthritis (POA) is evaluated. A literature review based on pre-specified criteria, revealed 36 articles for critical analysis related to intra-articular injuries of distal radius, acetabulum, distal femur and tibial plateau.In the distal radius, step-offs and gaps detected with precise measurement techniques have been correlated with a higher incidence of radiographic POA, but in the second 5 years after injury, a negative clinical impact of these radiographic changes has not been convincingly demonstrated. Restoring the superior weight-bearing dome of the acetabulum to its pre-injury morphology decreases POA and improves patient outcomes. Involvement of the posterior wall, however, seems to bean adverse prognostic sign. This effect may be independent of articular reduction. In the tibial plateau, articular incongruities appear to be well tolerated, and factors only partially related to articular reduction are more important in determining outcome than articular step-off alone;these include joint stability, retention of the meniscus, and coronal alignment. Based on observational approach and evaluation of the studies, factors other than just the extent of articular displacement affect the management of articular fractures. Different joints and even different areas of the same joint appear to have different tolerances for post-traumatic articular step-offs.

Management of post-traumatic malunion of fractures of the distal radius

Distal radius malunions are a common cause of patient morbidity. This review of the literature surrounding distal radius malunion covers the demographics, pathologic anatomy, and indications for surgery, surgical techniques, and salvage options. Particular emphasis is placed on subject areas that have not been reviewed as extensively in previous articles, including: intra-articular malunion, computer-assisted techniques, bone graft alternatives, and volar fixed-angle plate osteosynthesis.

Distal radius fractures

Distal radius fractures are a common injury, particularly in the elderly population. Severity of these fractures is directly related to the bone mineral density of the patient, and clinical results are dependent on this parameter as well. In terms of treatment, several options exist. Nonoperative management consists of closed treatment with casting. Operative treatment options include intrafocal pinning, nonbridging and bridging external fixation, arthroscopic-assisted external fixation, and various methods of open reduction internal fixation. When operative intervention is indicated, considerations include the characteristics of the fracture and the experience of the surgeon with the treatment modalities.

Treatment of intra-articular fractures of the distal radius

In a randomised prospective study, 20 patients with intra-articular fractures of the distal radius underwent arthroscopically- and fluoroscopically-assisted reduction and external fixation plus percutaneous pinning. Another group of 20 patients with the same fracture characteristics underwent fluoroscopically-assisted reduction alone and external fixation plus percutaneous pinning. The patients were evaluated clinically and radiologically at follow-up of 24 months. The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire and modified Mayo wrist score were used at 3, 9, 12 and 24 months postoperatively. In the arthroscopically- and fluoroscopically-assisted group, triangular fibrocartilage complex tears were found in 12 patients (60%), complete or incomplete scapholunate ligament tears in nine (45%), and lunotriquetral ligament tears in four (20%). They were treated either arthroscopically or by open operation. Patients who underwent arthroscopically- and fluoroscopically-assisted treatment had significantly better supination, extension and flexion at all time points than those who had fluoroscopically-assisted surgery. The mean DASH scores were similar for both groups at 24 months, whereas the difference in the mean modified Mayo wrist scores remained statistically significant.

Although the groups are small, it is clear that the addition of arthroscopy to the fluoroscopically-assisted treatment of intra-articular distal radius fractures improves the outcome. Better treatment of associated intra-articular injuries might also have been a reason for the improved outcome.

Management of post-traumatic malunion of fractures of the distal radius

Distal radius malunions are a common cause of patient morbidity. This review of the literature surrounding distal radius malunion covers the demographics, pathologic anatomy, and indications for surgery, surgical techniques, and salvage options. Particular emphasis is placed on subject areas that have not been reviewed as extensively in previous articles, including: intra-articular malunion, computer-assisted techniques, bone graft alternatives, and volar fixed-angle plate osteosynthesis.

A meta-analysis of outcomes of external fixation versus plate osteosynthesis for unstable distal radius fractures

PURPOSE

External fixation and open reduction and internal fixation have been the traditional techniques for surgical fixation of unstable distal radius fractures. The existing literature has not identified which is superior, primarily because of the lack of comparative trials. We performed a comprehensive systematic review and meta-analysis of the current literature on external fixation and internal fixation of distal radius fractures to determine the dominant strategy based on available scientific evidence.

METHODS

We searched MEDLINE and EMBASE for English-language articles published between 1980 and 2004 that satisfied predetermined inclusion and exclusion criteria. The outcomes of internal and external fixation were compared using continuous measures of grip strength, wrist range of motion, and radiographic alignment and categoric measures of pain, physician-rated outcome scales, and complication rates. Outcomes were pooled by random-effects meta-analysis and meta-regression analysis was used to control for patient age, presence of intra-articular fracture, duration of follow-up period, and date of publication. Sensitivity analyses were used to test the stability of the meta-analysis results under different assumptions.

RESULTS

Forty-six articles were included in the review with 28 (917 patients) external fixation studies and 18 (603 patients) internal fixation studies. Meta-analysis did not detect clinically or statistically significant differences in pooled grip strength, wrist range of motion, radiographic alignment, pain, and physician-rated outcomes between the 2 treatment arms. There were higher rates of infection, hardware failure, and neuritis with external fixation and higher rates of tendon complications and early hardware removal with internal fixation. Considerable heterogeneity was present in all studies and adversely affected the precision of the meta-analysis.

CONCLUSIONS

The current literature offers no evidence to support the use of internal fixation over external fixation for unstable distal radius fractures. Comparative trials using appropriately sensitive and validated outcome measurements are needed to guide treatment decisions.

New methods for assessing cartilage contact stress after articular fracture

Progress in reducing the incidence and severity of posttraumatic arthritis depends in part on avoiding deleterious stress levels at residual local incongruities. Systematic efforts to elucidate factors adversely influencing cartilage's mechanical environment in turn depend on the availability of suitable modalities to assess intraarticular contact stresses. This has been and remains a challenging biomechanical problem. Technologic approaches used in the past have included mathematical analyses and indwelling physical sensors, each with advantages and limitations. Two emerging, mutually complementary capabilities show promise of dramatically altering the state of the art in this important field. The first of these methodologies, voxel-based contact finite element analysis, provides accurate computational estimates of cartilage stress on a patient-specific basis, and does so while accommodating arbitrarily idiosyncratic patterns of local articular incongruity. The second methodology, instrumentational, involves transient pressure distribution recordings using specially designed piezoresistive array sensors. Operational considerations for both of these new assessment technologies are described, and promising directions for future development are outlined.

Remodeling of articular defects in an animal model

When treating displaced intraarticular fractures, the goal has been to restore normal articular cartilage contour to decrease local contact stresses that may lead to the development of posttraumatic osteoarthritis. To confirm observations that articular cartilage step-offs can remodel with time and to determine how the articular surface and subchondral bone remodels after an intraarticular fracture, joint surface changes were examined in a weightbearing sheep model with an intraarticular fracture. Articular surface pressure changes were observed across a 1-mm osteotomy. Twelve weeks after an intraarticular osteotomy, there was a decrease in differential pressure distribution between the normal articular cartilage and the depressed articular surface. Histologic analysis showed thinning of the articular cartilage on the high side of the osteotomy with collagen compression and bending of the collagen fibrils. On the low side of the osteotomy, increased chondrocyte cellularity and hypertrophy were observed. In addition, bending of collagen fibrils was observed in an unloaded state in an attempt to form a smooth overlapping shelf at the osteotomy site. Because intraarticular incongruency, with resultant joint contact pressure differences, seems to be involved in the development of posttraumatic arthritis, methods to improve cartilage remodeling may improve outcome after intraarticular fractures.

The role of biomechanics and inflammation in cartilage injury and repair

Osteoarthritis is a painful and debilitating disease characterized by progressive degenerative changes in the articular cartilage and other joint tissues. Biomechanical factors play a critical role in the initiation and progression of this disease, as evidenced by clinical and animal studies of alterations in the mechanical environment of the joint caused by trauma, joint instability, disuse, or obesity. The onset of these changes after joint injury generally has been termed posttraumatic arthritis and can be accelerated by factors such as a displaced articular fracture. Within this context, there is considerable evidence that interactions between biomechanical factors and proinflammatory mediators are involved in the progression of cartilage degeneration in posttraumatic arthritis. In vivo studies have shown increased concentrations of inflammatory cytokines and mediators in the joint in mechanically induced models of osteoarthritis. In vitro explant studies confirm that mechanical load is a potent regulator of matrix metabolism, cell viability, and the production of proinflammatory mediators such as nitric oxide and prostaglandin E2. Knowledge of the interaction of inflammatory and biomechanical factors in regulating cartilage metabolism would be beneficial to an understanding of the etiopathogenesis of posttraumatic osteoarthritis and in the improvement of therapies for joint injury.

Assessment of articular displacement of distal radius fractures

Intraarticular step and gap displacements represent the most common indication for surgical treatment of distal radius fractures. Most often, treatment decision making relies only on good-quality plain radiographs taken before and after reduction with measurement accuracy maximized by using the longitudinal axis method. When plain radiographs alone prove insufficient, CT scans or tomograms will significantly improve interobserver and intraobserver reliability of measurements, especially when evaluated using the arc method. Tomography is an effective method for postoperative evaluation of fractures immobilized in splints or casts. The role of MRI in assessing intraarticular distal radius fractures is limited to confirming injuries to carpal ligaments or the triangular fibrocartilage complex. Intraoperatively, we use fluoroscopy to obtain 30 degrees cephalad posteroanterior views and as 22 degrees lateral views to best observe articular surface reduction. Our current operative indications include fractures with radiocarpal or distal radioulnar joint step or gap deformities greater than 1-2 mm, gross distal radioulnar joint instability, or those with extensive metaphyseal comminution rendering them particularly unstable after closed reduction. In general, we tend to lean toward operative fixation in younger, more active patients.

Glenohumeral articular contact areas and pressures following labral and osseous injury to the anteroinferior quadrant of the glenoid

The objective of this study was to determine the effect of progressive labral and bone loss on the articular contact area and pressures across the glenohumeral joint under compressive loads of 220 and 440 N. Eight fresh-frozen cadaver shoulders were used, and contact pressures in 4 quadrants of the glenoid were determined with a Tekscan flexible tactile force sensor. Testing conditions included intact glenoids, glenoids with the anteroinferior labrum removed, and glenoids with 3 sizes of bone defects in the anteroinferior quadrant. By means of Tekscan sensing equipment, the measured contact area over the glenolabral complex was between 49.0% and 61.5% of the calculated surface area for the intact specimens. Loss of the anteroinferior labrum decreased contact area by 7% to 15% compared with the intact specimens, and the mean contact pressure increased by 8% to 20%. With bone loss corresponding to a defect measuring 30% of the diameter in the anteroinferior quadrant, contact area across the entire glenoid decreased a mean of 41% compared with the intact specimens, whereas the mean contact pressure increased nearly 100%. When the anteroinferior quadrant of the glenoid was analyzed separately, loss of the anteroinferior labrum alone resulted in an increase in the mean contact pressure in this quadrant compared with the intact specimens (mean, 53%). Bone loss of 30% of the diameter resulted in mean contact pressures in this quadrant increasing by 300% to 400% compared with the intact specimens, with 2 of 8 specimens becoming grossly unstable. In addition, with 30% diameter bone loss, the mean contact pressure decreased by 26% in the posterosuperior quadrant, indicating a shift in loading of the cadaveric glenoid. Peak pressures followed similar trends, with labral loss alone increasing peak pressures in the anteroinferior quadrant by a mean of 28% of that seen for the intact specimens.

The arthroscopic management of intra-articular distal radius fractures

Intra-operative arthroscopy and fluoroscopy provide improved visualisation and guide the restoration of intra-articular distal radial fractures while minimising the operative dissection required for their stabilisation. Radial styloid fractures, distal radial fractures with dorsal, palmar or combined ulnar-sided "die punch" fragments, palmar and dorsal Barton's fractures, and various three- and four-part intra-articular fractures without significant bone loss or defect are especially suited for this technique. The experienced arthroscopist may wish to apply the technique to more severely comminuted intra-articular fractures. Bone defects may be approached through a limited dorsal incision traversing the 3rd dorsal wrist compartment. Arthroscopy and fluoroscopy may be used adjunctively to assess fracture reduction and fixation. Arthoscopy further facilitates initial treatment by allowing direct joint visualisation, debridement, the removal of small free intra-articular fragments, and the recognition and early treatment of wrist ligament injuries, particularly those not appreciated by X-ray evaluation

Consequences of transverse acetabular fracture malreduction on load transmission across the hip joint

OBJECTIVE

To evaluate the biomechanical behavior of gap and step malreductions in a model of transverse acetabular fracture.

DESIGN

Cadaver pelvis loading in simulated single-leg stance with intact acetabulum, after transverse acetabular fracture anatomically reduced, and after step and gap malreduction. Five transtectal transverse fractures; five juxtatectal transverse fractures.

SETTING

Quasi-static loading of the hip with simulated abductor mechanism to physiologic loads with pressure-sensitive film interposed in the joint to determine contact area and contact pressure within the hip joint.

MAIN OUTCOME MEASUREMENT

Hip joint contact parameters: contact area, peak and mean contact pressure, and load distribution.

RESULTS

Step malreduction of the transtectal transverse fracture resulted in significantly increased peak contact pressures (20.5 megapascals) in the superior acetabular articular surface as opposed to the intact acetabulum (9.1 megapascals). Gap malreduction of transtectal transverse fracture and step and gap malreduction of juxtatectal fracture did not result in significantly increased contact pressures in the hip.

CONCLUSION

Step malreduction of a transverse acetabular fracture in the superior articular surface results in abnormally high contact forces and may predispose to the development of posttraumatic arthritis.