Lunate Facet Fragment Research Articles

Three-Dimensional Morphometric Analysis of the Volar Cortical Shape of the Lunate Facet of the Distal Radius.

In cases of distal radius fractures, the fixation of the volar lunate facet fragment is crucial for preventing volar subluxation of the carpal bones. This study aims to clarify the sex differences in the volar morphology of the lunate facet of the distal radius and its relationship with the transverse diameter of the distal radius. Sixty-four CT scans of healthy wrists (30 males and 34 females) were evaluated. Three-dimensional (3D) images of the distal radius were reconstructed from the CT data. We defined reference point 1 as the starting point of the inclination toward the distal volar edge, reference point 2 as the volar edge of the joint on the bone axis, and reference point 3 as the volar edge of the distal radius lunate facet. From the 3D coordinates of reference points 1 to 3, the bone axis distance, volar-dorsal distance, radial-ulnar distance, 3D straight-line distance, and inclination angle were measured. The transverse diameter of the radius was measured, and its correlations with the parameters were evaluated. It was found that in males, compared to females, the transverse diameter of the radius is larger and the protrusion of the volar lunate facet is greater. This suggests that the inclination of the volar surface is steeper in males and that the volar locking plate may not fit properly with the volar cortical bone of the lunate facet, necessitating additional fixation.

Open Reduction Maneuver for Distal Radius Fracture Involving an Intra-articular Sagittal Split

Open Reduction Maneuver for Distal Radius Fracture Involving an Intra-articular Sagittal Split

Risk Factors for the Incidence of the Volar Lunate Facet Fragments in Distal Radius Fractures.

Background The volar lip of the distal radius is the key structure for wrist joint stability. Rigid fixation of the volar lunate facet (VLF) fragment is difficult because of its unique anatomy, and a high rate of postoperative displacement was demonstrated. Purposes The aim of the study is to identify risk factors for VLF in distal radius fractures (DRFs) and to reconsider the important point for primary fixation. Patients and Methods One hundred fifty-five patients who underwent open reduction and internal fixation for an DRF were included and classified into one of the following two groups: VLF(+)or VLF(-). Demographic data, including age, sex, body mass index (BMI), laterality, trauma mechanism, and AO Foundation/Orthopaedic Trauma Association (AO/OTA) classification were recorded. Several parameters were investigated using wrist radiographs of the uninjured side and computed tomography scans of the injured side. Univariate and multivariate logistic regression analyses were performed to evaluate the risk factors for VLF. Results There were 25 patients in the VLF(+) group and 130 patients in the VLF(-) group. The incidence of VLF was 16.1%. The VLF(+) group tended to have a higher BMI and higher energy trauma mechanism. The odds ratio for the sigmoid notch angle (SNA), volar tilt (VT), and lunate facet curvature radius (LFCR) were 0.84, 1.32, and 0.70, respectively, with multivariate analysis, which was significant. A smaller SNA, larger VT, and smaller LFCR are potential risk factors for VLF. Conclusion Over-reduction of the VT at primary fixation should be avoided because it could place an excess burden on the VLF and cause subsequent postoperative fixation failure and volar carpal subluxation. Level of Evidence IV.

Evaluation of Ulnar Setting of Volar Locking Plates for Distal Radius Fractures Using Modified Skyline View

Volar lunate facet fragments in distal radius fractures are located at the center of the load in the wrist joint and, therefore, should be properly supported by the distal ulnar setting of volar locking plates to obtain better postoperative outcomes. This study evaluated the usefulness of the modified skyline view (MSV) in intraoperative fluoroscopy for the ulnar setting of volar locking plates by comparing it with that of the anteroposterior view (APV). Sixty-five patients with distal radius fractures who underwent open reduction and plate fixation as well as follow-up intraoperative fluoroscopy and postoperative computed tomography (CT) at our institution between April 2019 and March 2022 were included. The distance between the ulnar edge of the plate and the distal radius (d-value) was measured retrospectively using intraoperative fluoroscopy (distance measured from MSV and distance measured from APV) or postoperative CT (distance measured using postoperative CT). The distance measured from MSV and that measured from APV were compared with those measured using CT as the true values. Each measurement was performed twice by 2 examiners at an interval of 1 month. The comparison scores were evaluated using the intraclass correlation coefficient. The distance measured from MSV showed a difference of 0.6 ± 0.5 mm from that measured using CT, which was significantly smaller than that measured from APV (1.2 ± 0.9 mm; P < .001). Neither postoperative volar subluxation nor dislocation of bone fragments was found during the study period. Both intraclass correlation coefficient (1,1) and intraclass correlation coefficient (2,1) reliabilities were substantial to almost perfect. Modified skyline view is an effective and versatile imaging method for estimating the ulnar setting of volar locking plates; it provides measurements more similar to those provided by postoperative CT compared with APV. The use of MSV may reduce postoperative complications, such as volar subluxation and dislocation of bone fragments, especially in cases with volar lunate facet fragments in which the ulnar setting of the plate is significant. Diagnostic III.

Volar Lunate Facet Fractures of the Distal Radius: Fracture Mapping Using 3D CT Scans.

Background Fractures of the distal radius involving the lunate facet at the volar articular surface are unstable injuries and are usually managed operatively. Management of these fractures is challenging as our understanding of the exact fracture characteristics and associated injuries to the carpus is poor. Purpose This study aims to define the anatomy and associated injuries of lunate facet fractures using three-dimensional computed tomography (CT) scans and fracture mapping techniques. Methods A consecutive series of CT wrists was analyzed to identify intra-articular fractures involving the lunate facet at the volar distal radius. Fractures were mapped onto standardized templates of the distal radius using previously described fracture mapping techniques. We also identified instabilities of the carpus including volar carpal translation, ulnar translocation, scapholunate diastasis, and distal radioulnar joint (DRUJ) instability. Results We present 23 lunate facet fractures of the distal radius. The lunate facet fragment displaces in a volar and proximal direction and the lunate always articulates with the displaced fragment. The smaller fragments displace a greater amount, in a volar direction, with pronation. The fracture tends to occur between the origin of the short and long radiolunate ligaments. Conclusion Lunate facet fractures are frequently comprised of osteoligamentous units of the distal radius involving the short and long radiolunate ligaments and the radioscaphocapitate ligament. Assessment and management of volar carpal subluxation, scapholunate instability, ulnar translocation, and DRUJ instability should be considered. Clinical relevance Our mapping of these fractures contributes to our understanding of the anatomy and associated instabilities and will aid in surgical planning and decision making.

Volar versus combined dorsal and volar plate fixation of complex intraarticular distal radius fractures with small dorsoulnar fragment \u2013 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.

Volar Lunate Facet Rim Fractures: K-I Classification and Technique.

Background and Purpose It is difficult to capture and safely support a small volar lunate facet (VLF) fragment and obtain sufficient initial fixation. The challenge in treating VLF rim fractures has resulted in various management options. The purpose of this study was to evaluate the clinical and radiological outcomes of a consecutive series of VLF rim fractures of the distal radius treated surgically and to report the Kondo-Imatani (K-I) classification of these fractures, using computed tomography (CT) images and surgical technique, which is termed the Plate buttress and Double tiered subchondral support (PD) technique. Patients and Methods A retrospective review was conducted on 35 patients with VLF rim fractures that included postoperative clinical evaluations, CT images, and radiographs. Description of Technique The PD technique to stabilize the VLF fragment with an anatomical and low-profile volar locking plate (VLP). Results All fractures healed at the final follow-up; Mayo wrist performance score average was 81.7 points (45-100), and the quick disabilities of the arm, shoulder, and hand (quick-DASH) score average was 9.5 points (0-31.8), showing relatively good clinical results. Conclusion VLF rim fragments are not amenable to standard VLP fixation. Unstable fixation may result in postoperative correction loss, aseptic necrosis, malunion, radiocarpal subluxation, and wrist dysfunction. This report described the K-I classification for VLF rim fractures of the distal radius and surgical technique, termed the PD technique, to stabilize the VLF rim fragment with an anatomical and low-profile VLP. Level of Evidence This is a Level IV, case series study.

Impacted intraarticular fragments of distal radius fractures: A radiographic characterization and analysis of reliability and diagnostic accuracy

BackgroundReduction using ligamentotaxis may not be effective enough to treat impacted intraarticular fragments of distal radius fractures. Articular incongruence resulting from the loss of reduction is a risk factor for postoperative osteoarthritis and worse clinical outcome. This study aimed to analyze the radiographic characterization of the impacted intraarticular fragments of distal radius fractures using two/three-dimensional computed tomography (CT). Further, we assessed the reliability and diagnostic accuracy in detecting the fragments using plain radiographs. MethodsWe analyzed 167 three-dimensional CT images of the intraarticular distal radius fractures and selected 12 fractures with impacted intraarticular fragments. We recorded the location, size, and displacement of the fragment using CT images. In addition, six examiners evaluated 25 fractures including those 12 fractures having the fragments using plain radiographs for detecting the fragments and their displacements. Further, we evaluated the reliability and diagnostic accuracy of the plain radiographs in the detection of the fragment. ResultsFifteen impacted intraarticular fragments were found in 12 wrists. The displacement of the scaphoid facet fragment was significantly larger than that of the lunate facet fragment in CT measurement (7.0 mm and 3.6 mm). Inter and intraobserver reliability of the diagnosis for the fragment in plain radiographs were poor and fair (κ: 0.14 and κ:0.27). Diagnostic accuracy in detecting the fragment in plain radiographs generated mean sensitivity: 0.4, mean specificity: 0.73, and mean accuracy: 0.58. The mean sensitivity in detecting a lunate facet fragment was lower than that of a scaphoid facet fragment in plain radiographs (0.24 and 0.44). ConclusionImpacted intraarticular fragments were found in 7% of intraarticular distal radius fractures. We observed low reliability and sensitivity in detecting the fragment using plain radiographs. Preoperative recognition of the fragments using plain radiograph were difficult, even though the magnitude of step-off of the scaphoid facet fragment was large.

Comparison of clinical outcomes with and without volar lunate facet fragments in dorsal displaced distal radius fractures.

Introduction: Although many clinical studies about distal radius fracture (DRF) accompanied by volar lunate facet fragments (VLFF) have recently been reported, none focus on the direction of displacement of distal fragments. Many previous cases with difficulty in treating DRF with VLFF were volar-displaced fractures. Thus, the postoperative risk for re-displacement is different between volar- and dorsal-displaced fractures with VLFF. The aim of this study is to compare the outcome of dorsal-displaced fractures treated using proximal volar locking plates (PVLP) between those with VLFF and those without, in order to reconsider the indications of distal volar locking plates (DVLP) and investigate the possibility of treating dorsal-displaced DRF with VLFF using PVLP. Methods: The subjects were 122 patients with dorsal-displaced DRFs treated using PVLP (42 males and 80 females, mean age: 59.2 years old). The patients were divided into 13 patients with VLFF group and 109 patients without VLFF group, and the clinical outcomes at 12 months after surgery were compared. Results: No significant difference was noted on any evaluation between the groups. In addition, no postoperative re-displacement of VLFF was observed and bone union was confirmed. Furthermore, no osteoarthritic change was noted in all patients. Conclusions: We confirmed that surgical treatment for dorsal-displaced DRF using PVLP is possible even in cases of DRF with VLFF. In addition, DVLP is an implant with a high complication risk; therefore, it may be necessary to reconsider the use of DVLP for dorsal-displaced DRF with VLFF treatable by PVLP.

Outcomes of Supplementary Spring Wire Fixation With Volar Plating for Volar Lunate Facet Fragments in Distal Radius Fractures.

Intra-articular distal radius fractures with small volar lunate facet fragments can be challenging to address with volar plate fixation alone. Volar locked plating with supplementary spring wire fixation has been previously described in a small series but has not been further described in the literature. We hypothesized that this technique can provide adequate fixation for volar lunate facet fragments smaller than 15 mm in length, which are at risk of displacement. We completed a retrospective chart review (2015-2019) of patients who underwent volar locked plating with the addition of supplementary spring wire fixation for intra-articular distal radius fractures with a volar lunate facet fragment (<15 mm). Postoperative radiographs were assessed to evaluate union, evidence of hardware failure, escape of the volar lunate facet fragment, and postoperative volar tilt. Clinical outcome was assessed with wrist flexion/extension, arc of pronosupination, and Quick Disabilities of the Arm, Shoulder, and Hand Score (QuickDASH) scores. Fifteen patients were identified, of which all went on to fracture union. There were no hardware failures or escape of the volar lunate facet fragment at final follow-up. One patient underwent hardware removal for symptoms of flexor tendon irritation. The mean wrist flexion was 59°, wrist extension was 70°, pronation was 81°, and supination was 76°. The mean QuickDASH score was 18.5. The mean postoperative volar tilt was 3.6°. Supplementary spring wire fixation with standard volar plating provides stable fixation for lunate facet fragments less than 15 mm. This technique is a safe and reliable alternative to commercially available fragment-specific implants.

Fracturas marginales volares de radio distal: fijación con clavijas adicionales a la placa volar.

Introducción: El tratamiento de las fracturas de muñeca con placas volares bloqueadas puede ser insuficiente para las fracturas con fragmentos volares marginales distales a la línea de inserción distal del pronador cuadrado, sitio de inserción de importantes ligamentos. Objetivo: Evaluar la reproducibilidad de la técnica y los resultados del tratamiento de fracturas marginales volares de radio distal con clavijas, capturando el fragmento volar y dejándolas debajo de la placa volar bloqueada de radio distal. Materiales y Métodos: La técnica quirúrgica utiliza una o varias clavijas para fijar el fragmento volar semilunar del radio distal, bloqueándolas debajo de la placa. Inicialmente efectuamos una simulación cadavérica. Luego, realizamos un estudio retrospectivo que incluyó a 7 pacientes con fracturas de radio distal intrarticular con un fragmento marginal volar distal a la línea de la orilla, tratados entre septiembre de 2014 y febrero de 2015. El promedio de edad era de 53 años, y el del seguimiento, de 16 meses. Se obtuvieron radiografías en sucesivos controles. Al alta se evaluaron el rango de movilidad, la fuerza de prensión y dos puntajes funcionales. Resultados: Todas las fracturas consolidaron satisfactoriamente manteniendo la reducción del fragmento marginal volar. No hubo casos con inestabilidad radiocubital inferior como secuela. Conclusión: La fijación adicional del fragmento marginal volar lunar del radio con clavijas dobladas por debajo de la placa ofrece una alternativa de estabilización sencilla, económica y adecuada para suplir la fijación de un fragmento que la placa sola no estabilizaría adecuadamente.&#x0D; Nivel de Evidencia: IV&#x0D;

Implication de la facette lunaire palmaire dans les fractures articulaires du radius distal

BackgroundSmall fracture fragments of the palmar lunate facet of the distal radius can be difficult to stabilize and may cause loss of reduction and even subluxation of the radiocarpal joint. Material and methodsThe aims of the study were to investigate fracture patterns of the intermediate column in 101 intra-articular distal radius fractures with three-dimensional computed tomography, and to determine the prevalence of palmar lunate facet fracture fragments. The size of the fragments was measured to find out how many fragments were small. ResultsThe palmar lunate facet fragment was present in 61 fractures. Mean length of the palmar cortex measured 13.5mm (range: 3 to 26.9) and mean area of the lunate facet 115mm2 (range: 31 to 267). Seventeen percent of intra-articular distal radius fractures had a palmar lunate facet fragment with a short palmar cortex. ConclusionWith accurate analysis of the preoperative computed tomography scans the typical fracture patterns of the palmar lunate facet are recognisable and adequate fixation technique can be chosen to avoid loss of reduction. Level of evidenceIV.

Volar plate fixation in intra-articular distal radius fractures with a volar lunate facet fragment

The aims of the study were to determine whether a volar lunate facet fragment is present in 67 displaced intra-articular distal radius fractures and to investigate which factors are associated with reduction loss after treatment with a volar plate and locking screws. The fractures were analyzed preoperatively with three-dimensional computed tomography. The volar lunate facet fragment was present in 42 fractures. Reduction loss occurred in five wrists and in two of those, the carpus was subluxated. Loss of reduction was associated with a short palmar cortex (9mm or less) of the volar lunate facet fragment. This study has shown that measuring the length of the palmar cortex of a volar lunate facet fracture fragment may be useful for identifying distal radius fractures that have a higher risk of displacement after treatment with a standard volar plate and locking screws.

Involvement of the palmar lunate facet in intra-articular distal radius fractures

BackgroundSmall fracture fragments of the palmar lunate facet of the distal radius can be difficult to stabilize and may cause loss of reduction and even subluxation of the radiocarpal joint. Material & methodsThe aims of the study were to investigate fracture patterns of the intermediate column in 101 intra-articular distal radius fractures with three-dimensional computed tomography, and to determine the prevalence of palmar lunate facet fracture fragments. The size of the fragments was measured to find out how many fragments were small. ResultsThe palmar lunate facet fragment was present in 61 fractures. Mean length of the palmar cortex measured 13.5mm (range: 3 to 26.9) and mean area of the lunate facet 115 mm2 (range: 31 to 267). Seventeen percent of intra-articular distal radius fractures had a palmar lunate facet fragment with a short palmar cortex. ConclusionWith accurate analysis of the preoperative computed tomography scans the typical fracture patterns of the palmar lunate facet are recognisable and adequate fixation technique can be chosen to avoid loss of reduction. Level of evidenceIV.

Metacarpal Position and Lunate Facet Screw Fixation in Dorsal Wrist-Spanning Bridge Plates for Intra-Articular Distal Radial Fracture

A dorsal wrist-spanning plate (DWSP) can be affixed to the second or third metacarpal, depending on the morphology of the distal radial fracture (DRF) and on surgeon preference, but comparative biomechanical analyses between these methods are limited. This biomechanical study compared fixation to the second metacarpal versus the third metacarpal as measured by lunate facet fragment displacement in a cadaveric model of an axially loaded intra-articular DRF. The construct rigidity with the addition of an intrafragmentary lunate facet locking screw was also evaluated. A sample size of 14 cadaveric matched pairs was calculated to achieve 81.7% power. The 28 limbs were randomized to DWSP fixation to the second metacarpal (Group 1) or third metacarpal (Group 2); each wrist underwent an osteotomy simulating an unstable intra-articular DRF. Limbs were tested at axial loads of 50, 100, 150, 200, 250, and 300 N. Lunate facet displacement from the metaphyseal fragment at each load was measured with use of differential variable reluctance transducers. After initial testing, a locking screw was placed through the plate into the lunate facet fragment in the third metacarpal group (Group 3). Displacement measurements were repeated for all loads. Paired 2-tailed t tests with Bonferroni correction (significance, p < 0.008) were performed to assess differences in fragment stability between groups. The average fracture displacement at 300 N was 0.8 mm in Group 1, 0.4 mm in Group 2, and 0.2 mm in Group 3. Plating to the third metacarpal more effectively resisted displacement compared with the second metacarpal at all axial loads (p < 0.008). The addition of a lunate facet screw further stiffened the construct at loads of ≥200 N (p < 0.008). Plate fixation to the third metacarpal with an intrafragmentary screw was the most biomechanically favorable construct, although other factors may favor an alternative distal fixation site. Mean displacement of the lunate facet fragment at 300 N was <1 mm in all groups. The present study demonstrated that a DWSP affixed to the third metacarpal with an intrafragmentary screw provides the most effective stabilization of the lunate facet fragment in intra-articular DRFs. This study validates the use of intrafragmentary screws to increase stability in DWSP fixation.

Plate coverage predicts failure for volarly unstable distal radius fractures with volar lunate facet fragments.

Introduction: Loss of reduction after operative fixation of volarly unstable distal radius fractures with a volar lunate facet fragment (VLF) is considered problematic because it results in carpal subluxation or dislocation and subsequent impaired function. We hypothesized that the indicator of loss of reduction of the VLF after fixation is plate coverage of the bony fragment. We investigated the relationship between the plate coverage of the VLF and loss of reduction after fixation, and calculated the plate coverage that was associated with failure of fixation of the VLF.Materials and methods: We conducted a retrospective review. We included patients with surgically treated volarly unstable distal radius fractures with VLF with a volar locking plate who had a minimum follow-up of 6 months. A total of 33 patients (35 wrists) met criteria for inclusion into the study. The patients were divided into a displacement group and a non-displacement group. We calculated and compared longitudinal dimension and plate coverage of the VLF between the two groups to reveal the risk factors for loss of reduction.Results: At final follow-up, 25 fractures maintained radiographic alignment and 10 (28.6%) lost reduction. Univariate analysis between the two groups showed that plate coverage against the transverse and longitudinal dimension of the VLF was correlated with loss of reduction after operative fixation. In multivariate logistic regression analysis, only plate coverage against the longitudinal dimension of the VLF remained a significant predictor of failure. With 64.7% as the cut-off point for plate coverage against the longitudinal dimension of the VLF, the sensitivity and specificity of the prediction were 96% and 80%, respectively.Conclusion: The predictor of loss of reduction after fixation of volarly unstable distal radius fractures with a VLF was plate coverage against the longitudinal dimension of the VLF.

Surgical treatment for distal radius fracture with volar lunate facet fragments: Importance of plate selection considering direction of displacement

Surgical treatment for distal radius fracture with volar lunate facet fragments: Importance of plate selection considering direction of displacement

Integrated Compression Screw Stabilization of the Dorsal Lunate Facet in Intra-Articular Distal Radius Fractures

To evaluate outcomes of intra-articular distal radius fractures with displaced dorsal lunate facet fragments treated with a combination of volar plating and the use of a dorsal screw that integrates into the plate. We reviewed a retrospective cohort of 22 patients who underwent open reduction and internal fixation of an intra-articular distal radius fracture with a volar plate in conjunction with the Frag-Loc Compression screw. Patient charts and radiographs were reviewed for clinical and radiographic outcomes. A total of 12 patients with a minimum 6-month follow-up who metall eligibility criteria were included in this study. There were 8 women and 4 men. The mean age was 55.2 years. Mean follow-up was 11.5 months (range, 6-21 months). The most common mechanism of injury was a fall from standing (75.0%). At final follow-up, all patients were able to return to their previous level of function. Bony union was achieved in all patients at the time of final follow-up. Average radiographic parameters at final follow-up were radial inclination 24.2° ± 5.3°, volar tilt 1.3° ± 5.2°, and ulnar variance 0.9 ± 1.7 mm. During the follow-up period, transient median nerve paresthesias were observed in 4 patients, with spontaneous resolution in 3 of 4 patients. Loss of articular reduction was not observed in any case. This study demonstrates satisfactory clinical and radiographic results and minimal complications with utilization of a new fixation device for distal radius fractures with displaced dorsal lunate facet fragments. Therapeutic IV.

Volar Locking Plate Fixation for Intra-Articular Distal Radius Fractures with Volar Lunate Facet Fragments Distal to the Watershed Line.

Standard volar plating of distal radius fractures may not adequately fix the volar lunate facet (VLF) fragment, which can result in volar carpal subluxation. We hypothesized that the size of VLF fragments distal to the watershed line might affect reduction loss after distally placed volar locking plate fixation for intra-articular distal radius fracture and examined if the presence of small displaced VLF fragments was a risk factor for reduction loss. Twenty-seven hands of 27 patients with intra-articular distal radius fractures with VLF fragments distal to the watershed line were treated by using Acu-Loc 2 volar distal radius locking plate fixation. At final follow-up, the mean Mayo Performance Score was 90.9, and the mean Quick Disabilities of Arm, Shoulder, and Hand score was 13.6. On radiography, 5 patients had a reduction loss of >2 mm in ulnar variance from immediately postoperatively to final follow-up (group 1), while 27 had no reduction loss (group 2). The mean longitudinal, transverse, and anteroposterior lengths and joint surface area of the VLF fragment were significantly smaller in group 1 than in group 2. Three-dimensional computed tomography revealed that the fracture patterns of the radiocarpal and distal radioulnar joints in group 1 were mainly volar-displaced VLF fragments. By stabilizing fragments, distally placed volar locking plate fixation effectively treated intra-articular distal radius fractures with VLF fragments distal to the watershed line. However, the presence of small displaced VLF fragments may increase the risk of reduction loss in ulnar variance.

Size and stabilization of the dorsoulnar fragment in AO C3-type distal radius fractures

IntroductionVolar locking plate (VLP) fixation has become the gold-standard treatment for distal radius fractures (DRFs). Especially, internal fixation of the volar lunate facet fragment is essential for the treatment of AO C3-type DRFs. On the other hand, the necessity of the fixation of the dorsal lunate facet fragment (dorsoulnar fragment) remains unclear. The purpose of the present study was to measure three-dimensionally the size of the dorsoulnar fragments in AO C3-type DRFs using computed tomography (CT) images in detail, and to reveal relationships of the size and stabilization of the dorsoulnar fragment with postoperative fracture displacement after VLP fixation. Materials and methodsWe retrospectively reviewed the 101 consecutive Japanese patients who underwent surgical treatment for AO C3-type distal radius fractures. If patient had dorsoulnar fragment, the three-dimensional size of this fragment and the occupying ratio to the radiocarpal joint (RCJ) and the distal radioulnar joint (DRUJ) were anatomically evaluated using the preoperative CT images. In addition, we investigated the relationship of the size and stabilization of the dorsoulnar fragment with fracture displacement after VLP fixation. We statistically compared the size parameters and occupying ratio of the dorsoulnar fragment between the displaced group and the stable groups using a two-tailed t-test. We also statistically compared the numbers of screws inserted into the dorsoulnar fragments between the displaced and stable groups using a chi-square test. ResultsThe mean dorsoulnar fragment size was 9.4 mm × 7.9 mm × 11.0 mm and the occupying ratio to the DRUJ and RCJ was 50% and 10%, respectively. The number of patients treated with volar locking plate fixation was 77, of which 12 patients had postoperative displacements. Although the size of the dorsoulnar fragment was not associated with postoperative displacement, stabilization following screw insertion into the dorsoulnar fragment was significantly associated with displacement. ConclusionStabilization of the dorsoulnar fragment with at least one screw of the volar locking plate was necessary to prevent postoperative fracture displacement regardless of dorsoulnar fragment size in AO C3-type distal radius fractures.