Distal radioulnar joint kinematics in simulated dorsally angulated distal radius fractures

Fracture Severity and Triangular Fibrocartilage Complex Injury in Distal Radius Fractures with or without Osteoporosis

The purpose of this study was to investigate the fracture morphology of distal radius fractures (DRFs) with the status of triangular fibrocartilage complex (TFCC) foveal insertion in patients with or without osteoporosis and to identify the relationship between osteoporosis and foveal tear. Seventy-five patients who underwent surgery for DRF from January 2021 to September 2023 were included. All patients were evaluated by standard radiography and dual-energy X-ray absorptiometry and underwent a 3.0 T magnetic-resonance imaging examination of the involved wrist to identify TFCC foveal tear. Patients were allocated into two groups according to the presence of osteoporosis: patients with osteoporosis (group I) and those without osteoporosis (group II). Group I showed a significantly larger displacement of fractures compared to group II (radial inclination; 13.7 ± 5.4 vs. 17.9 ± 4.2; p < 0.001, dorsal angulation; 22.2 ± 12.1 vs. 16.5 ± 9.4; p = 0.024, ulnar variance; 4.15 ± 2.1 vs. 2.2 ± 1.9; p < 0.001). Dorsal angulation and ulnar variance were found to be independent prognostic factors for TFCC foveal tear in logistic regression analysis. Displacement of fractures was related to osteoporosis, and dorsal angulation and ulnar variance were independent prognostic factors for TFCC foveal tear. However, osteoporosis was not identified as a factor associated with TFCC foveal tears.

Association between imaging parameter changes and triangular fibrocartilage complex injury after distal radius fractures

BACKGROUND

Triangular fibrocartilage complex (TFCC) injury is a frequent soft tissue injury that has been observed to accompany distal radius fractures (DRFs) with concomitant changes in radiologic parameters. The aim of this study was to investigate the relevance of distal radial radiologic parameters associated with DRF and traumatic TFCC injury.

METHODS

A total of 172 patients with distal radius fractures who underwent X-ray, CT, and MRI before undergoing volar locking plate or external splint fixation between October 2021 and December 2022 were included in this study. An analysis of various radiologic parameters and the classification of fracture type and TFCC injuries by CT and MRI was performed. All patients were divided into the TFCC uninjured group and the injured group. The incidence and relevant radiologic parameters were compared.

RESULTS

This study included 76 males and 96 females with a mean age of 56.1 years. Among all patients, 33 (19.2%), 40 (23.2%), and 99 (57.6%) had DRF with A, B, and C fractures, respectively, according to the AO/OTA classification. In patients with fractures, the TFCC was found to be injured in 54.1% (93/172) of patients (type 1A in 21, 1B in 46, 1C in 39, and 1D in 35) but uninjured in 45.9% (79/172). There were significant differences between the TFCC injured and uninjured groups regarding the radius length (p = 0.044) and DRUJ distance (p = 0.040) of radiologic parameters that changed with DRF, although there were no differences between the two groups regarding gender, age, injured side, intra- and extra-articular, radius inclination and palmer tilt angle, or sagittal translation. Within the TFCC injured group, the radius length and DRUJ distance were 4.83 mm and 2.95 mm less or wider than 7.19 mm and 1.83 mm of the uninjured group. Moreover, shorter radius length was related to type lB TFCC injury (p = 0.041). Both radius length (AUC = 0.658) and DRUJ distance (AUC = 0.582) had no convincing predictive value for TFCC injury in DRF.

CONCLUSION

1B TFCC injury is most common in patients with DRF and concomitant TFCC injury. Both radius length and DRUJ distance have a significant statistical correlation with TFCC injury, and patients with TFCC injury tend to have a shortened radius and wider DRUJ distance, although they have no predictive value for TFCC injury in DRF. In addition, a shorter radius length was related to type lB TFCC injury.

Corrective Osteotomy of Malunited Forearm Fractures for Volar Distal Radioulnar Joint Instability: A Case Report

CASE

A 6-year-old girl who had midshaft forearm fractures treated conservatively had volar distal radioulnar joint (DRUJ) instability caused by radial malunion at the 1-year follow-up. Corrective osteotomy was planned using computer-aided design (CAD) software based on computed tomography images. According to the analysis, the radial bone had an 8° apex volar deformation in the sagittal plane. Corrective osteotomy was performed based on preoperative planning. After surgery, the patient regained full function of her right forearm without volar DRUJ instability.

CONCLUSION

This case report shows that corrective osteotomy with 3D CAD analysis can help surgeons plan and accurately correct malunion.

The distal radioulnar joint after distal radial fractures: when and how do we need to treat pain, stiffness or instability?

The importance of distal radioulnar joint problems associated with distal radial fractures is recognized increasingly. But there remains considerable disagreement about how to treat these problems both acutely and chronically. This review outlines the knowledge about the natural history of ulnar-sided wrist problems with distal radials fractures. In particular, the recent increased understanding of the almost inevitable joint instability associated with distal radial fractures is highlighted, including the unreliability of clinical assessment and hence why there has been so much misunderstanding. Provided there is reasonable bony alignment, most ulnar-sided wrist problems can be treated non-operatively initially (typically for over a year) in anticipation of substantial improvement with time. The exception is early marked subluxation of the distal radioulnar joint (DRUJ) blocking forearm rotation, which needs urgent (typically closed) reduction.

A simple tool for volar tilt restoration during volar plate osteosynthesis of distal radius fracture: A technical note

Anatomical restoration of volar tilt is a technical challenge in a displaced distal radius fracture with a dorsally angulated fracture pattern accompanied by dorsal metaphyseal comminution. We adopted a reduction technique using a mini-Hohmann retractor, to accomplish the desired volar tilt in a controlled fashion. We would like to present this technical note through a case example describing the technique specifics along with one-year postoperative outcomes.

Pathomechanism of Triangular Fibrocartilage Complex Injuries in Patients with Distal-Radius Fractures: A Magnetic-Resonance Imaging Study

Injury to the triangular fibrocartilage complex (TFCC) is one of the most common complications following a fracture of the distal radius. In this study, an examination of TFCC injuries in patients with distal-radius fractures was conducted using magnetic-resonance imaging (MRI); the aim of the study was to analyze the prevalence of TFCC injury as well as to suggest acceptable radiologic parameters for use in prediction of the injury pattern. Fifty-eight patients with distal-radius fractures who underwent MRI prior to undergoing open-reduction surgery between April 2020 and July 2021 were included in this study. An analysis of various radiologic parameters, the fracture type, and the MRI classification of TFCC injuries was performed. Radiologic parameters were used in the evaluation of distal radioulnar joint (DRUJ), radial shortening, and the dorsal angularity of the fracture. All of the patients in this study had definite traumatic TFCC injuries. A statistical relationship was observed between the radial length gap between the intact wrist and the injured wrist, which represents relative radial shortening, and the pattern of TFCC injury. In conclusion, the shortening of the distal radius, causing peripheral soft tissue of the ulnar side to become tauter, is highly relevant with regard to the pattern of TFCC injury. However, because no data on the clinical outcome were utilized in this study, it is lacking in clinical perspective. The conduct of further studies on patients’ clinical outcome will be necessary.

Design and Performance Analysis of a Dynamic Magnetic Resonance Imaging-Compatible Device for Triangular Fibrocartilage Complex Injury Diagnosis

Pain and injury of the triangular fibrocartilage complex (TFCC) due to overuse or trauma are commonly diagnosed through static MRI scanning, while TFCC is always involved in radial and ulnar deviation of the wrist. To the best of our knowledge, a dynamic MRI diagnostic method and auxiliary tool have not been applied or fully developed in the literature. As such, this study presents the design and evaluation of a dynamic magnetic resonance imaging (MRI) auxiliary tool for TFCC injury diagnosis. First, 3D scanning and Python are used to measure and fit the radial and ulnar deviation trajectories of healthy participants and patients. 3D printing is then used to manufacture the auxiliary tool for dynamic MRI, and dynamic MRI diagnosis is then conducted to explore the clinical effect. The radial and ulnar deviation trajectory is presented as an asymmetric curve without an obvious circular centre, and the results indicate that the designed auxiliary device meets the requirements of the ulnar and radial movements of the human wrist. According to the MRI contrast test results, the image quality score of patients wearing the auxiliary device is higher than for those without. Such devices could assist clinicians in the diagnosis of TFCC damage, and our method could not only serve as the reference standard for clinical noninvasive diagnosis but also help in understanding the disease and improving the accuracy of TFCC diagnosis.

Casting Without Reduction Versus Closed Reduction With or Without Fixation in the Treatment of Distal Radius Fractures in Children: Protocol for a Randomized Noninferiority Trial

Background

Acute treatment for distal radius fractures, the most frequent fractures in the pediatric population, represents a challenge to the orthopedic surgeon. Deciding on surgical restoration of the alignment or cast immobilization without reducing the fracture is a complex concern given the remodeling potential of bones in children. In addition, the lack of evidence-based safe boundaries of shortening and angulation, that will not jeopardize upper-extremity functionality in the future, further complicates this decision.

Objective

The authors aim to measure functional outcomes, assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Physical Function v2.0 instrument. The authors hypothesize that outcomes will not be worse in children treated with cast immobilization in situ compared with those treated with closed reduction with or without percutaneous fixation. The authors also aim to compare the following as secondary outcomes: ulnar variance and fracture alignment in the sagittal and coronal planes, range of motion, pressure ulcers, pain control, radius osteotomy due to deformity, pseudoarthrosis cure, and remanipulation.

Methods

This is the protocol of a randomized noninferiority trial comparing upper-extremity functionality in children aged 5 to 10 years, after sustaining a distal radius fracture, treated with either cast immobilization in situ or closed reduction with or without fixation in a single orthopedic hospital. Functional follow-up is projected at 6 months, while clinical and radiographic follow-up will occur at 2 weeks, 3 months, and 9 months.

Results

Recruitment commenced in July 2021. As of January 2022, 23 children have been randomized. Authors expect an average of 5 patients to be recruited monthly; therefore, recruitment and analysis should be complete by October 2024.

Conclusions

This experimental design that addresses upper-extremity functionality after cast immobilization in situ in children who have sustained a distal fracture of the radius may yield compelling information that could aid the clinician in deciding on the most suitable orthopedic treatment.

Trial Registration

ClinicalTrials.gov NCT05008029; https://clinicaltrials.gov/ct2/show/NCT05008029

International Registered Report Identifier (IRRID)

DERR1-10.2196/34576

Failed Triangular Fibrocartilage Complex Repair and Reconstruction

Unsuccessful triangular fibrocartilage complex (TFCC) repair or reconstruction is poorly defined, often stemming from multiple causes, both patient and surgeon-related. Complete evaluation of the patient's psychosocial status and involvement in any litigation claims is essential, as is a thorough history, physical examination, and imaging workup to accurately diagnose TFCC injury, along with any concomitant wrist pathology. Awareness of common complications and technical errors is critical, and preventive treatment strategies should be implemented to minimize these events.

Distal Radius Fracture and the Distal Radioulnar Joint

In this article, we discuss the incidence and types of injuries to the distal radioulnar joint (DRUJ) that occur in the setting of a distal radius fracture. We review the anatomy of the distal radioulnar joint, which is critical to understanding its biomechanics, and how injury could cause symptomatic incongruency and instability. We highlight how patients with an injury to the distal radioulnar joint might present both at the time of injury and after treatment of a distal radius fracture, the appropriate workup, the available treatment options, and the evidence-based literature.

Patient-reported outcomes after corrective osteotomy for a symptomatic malunion of the distal radius

AIMS

The primary aim of this study was to describe patient satisfaction and health-related quality of life (HRQoL) following corrective osteotomy for a symptomatic malunion of the distal radius.

METHODS

We retrospectively identified 122 adult patients from a single centre over an eight-year period who had undergone corrective osteotomy for a symptomatic malunion of the distal radius. The primary long-term outcome was the Patient-Rated Wrist Evaluation (PRWE) score. Secondary outcomes included the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score, the EQ-5D-5L score, complications, and the Net Promoter Score (NPS). Multivariate regression analysis was used to determine factors associated with the PRWE score.

RESULTS

Long-term outcomes were available for 89 patients (72%). The mean age was 57 years (SD 15) and 68 were female (76%). The median time from injury to corrective osteotomy was nine months (interquartile range (IQR) 6 to 13). At a mean follow-up of six years (1 to 11) the median PRWE score was 22 (IQR 7 to 40), the median QuickDASH score was 11.4 (IQR 2.3 to 31.8), and the median EQ-5D-5L score was 0.84 (IQR 0.69 to 1). The NPS was 69. Multivariate regression analysis showed that the presence of an associated ulnar styloid fracture was the only significant independent factor associated with a worse PRWE score when adjusting for confounding variables (p = 0.004).

CONCLUSION

We found that corrective osteotomy for malunion of the distal radius can result in good functional outcomes and high levels of patient satisfaction. However, the presence of an ulnar styloid fracture may adversely affect function. Level of Evidence: III (cohort study). Cite this article: Bone Joint J 2020;102-B(11):1542-1548.

Instability in the Setting of Distal Radius Fractures: Diagnosis, Evaluation, and Treatment

Distal radius fractures with severe displacement or concomitant triangular fibrocartilage complex tears may be accompanied by distal radioulnar joint instability. Clinicians should examine the distal radioulnar joint closely when managing wrist fractures and treat coexisting instability appropriately. Chronic instability from distal radius malunion may require osteotomy or radioulnar ligament reconstruction. With proper management, most patients recover forearm stability and rotational motion after distal radius fracture.

Habitual volar dislocation of the ulnar head with a locked distal radioulnar joint after distal radius fracture: A case report

RATIONALE

Habitual volar dislocation of the ulnar head with a locked distal radioulnar joint (DRUJ) is a rare complication after distal radius fracture. We present a case of habitual volar dislocation of the ulnar head in a woman with a dorsally displaced malunited distal radius fracture.

PATIENT CONCERNS

A 72-year-old woman presented with occasional painful locking of the forearm in full supination. She had fractured the left distal radius in a fall 6 months previously. The fracture had been treated non-surgically with wrist immobilization in a long and short arm cast for 6 weeks. Physical examination showed no swelling of the left hand. The wrist locked when the forearm was fully supinated, and the patient was not able to pronate her forearm without reducing the ulna by pressing the left ulna down toward the DRUJ. She experienced sharp pain during the reduction procedure and pronation of the left forearm. The affected wrist had 91% motion compared with the contralateral wrist.

DIAGNOSIS

Radiography and computed tomography showed 28° dorsally angulated malunion of the distal radius and ulnar head subluxation with respect to the radius. Magnetic resonance imaging revealed disruption of the ulnar-side triangular fibrocartilage complex (TFCC) from the ulna fovea.

INTERVENTIONS

The patient desired surgery to address the painful click during full supination of her left wrist and the limitations in her activities of daily living. Corrective osteotomy of the distal radius and arthroscopic repair of the ulnar-side tear of the TFCC were performed. The TFCC was arthroscopically repaired to the ulnar fovea to stabilize the DRUJ.

OUTCOMES

At 1 year postoperatively, radiography showed complete union of the radius. The affected side had 97% wrist motion compared with the contralateral wrist and a full range of forearm rotation without pain or clicking. The grasp strength was 100% compared with the normal wrist.

LESSONS

Malunited distal radius fracture with concomitant TFCC injury can result in habitual volar dislocation of the ulnar head due to severely dorsally angulated malunion of the radius and avulsion of the ulnar-side TFCC from the ulna fovea. This condition required corrective osteotomy plus TFCC repair.

The effect of coordinate system selection on wrist kinematics

Three-dimensional motion analysis of the hand and wrist is common in in-vitro and in-vivo biomechanical research. However, all studies rely on post testing analysis, where anatomical joint coordinate systems (JCS) are created to generate clinically relevant data to describe wrist motion. The purpose of this study was to present a comparison of four JCS that have been previously described in literature. Five cadaveric upper limbs were passively cycled through a flexion-extension and radial-ulnar deviation motion pathways using a wrist motion simulator. During testing, clinical wrist angle was measured using a goniometer. Following testing, wrist angle was calculated using four previously described methods of generating wrist coordinate systems, to facilitate their comparison. For flexion-extension wrist motion, only subtle difference between JCSs were detected. When comparing the performance of each JCS to the measured wrist angle during flexion-extension wrist motion, the RMSE for all three analyzed axes were all within 6.6°. For radial-ulnar deviation wrist motion, again only subtle difference between JCSs were detected. When comparing the performance of each JCS to the measured wrist angle during radial-ulnar deviation wrist motion, the RMSE for all three analyzed axes were all within 7.1°. The results of this coordinate system comparison do not favor one JCS generation method over another, as all were found to be similar and the small differences that were found are likely not clinically significant. We support using any of the analyzed coordinate system generation methods; however, a practical advantage of using certain methods is that the required digitized points to form the coordinate systems are palpable on the skin's surface.

The Capitate-to-Axis-of-Radius Distance (CARD): A New Radiographic Measurement for Wrist and Carpal Alignment in the Sagittal Plane

PURPOSE

To determine the reliability of a new radiographic index evaluating sagittal radiocarpal alignment, the capitate-to-axis-of-radius distance (CARD). A secondary purpose was to validate this index by comparing values between normal wrists and those with distal radial fractures (DRFs) and rheumatoid arthritis (RA).

METHODS

The CARD is defined as the perpendicular distance from the center of the capitate head to the axis of the radius. Inter- and intraobserver reliability was tested. Cronbach alpha was calculated, and 2 methods of measurement were compared. The superior one (volar border of radial shaft) was used in the second part of the study. The normal CARD was then compared with unilateral DRFs with dorsal displacement DRF (n = 25) and RA (n = 25). Correlations between the CARD and other radiographic parameters (dorsal angulation, radial inclination, and ulnar variance) were calculated as well as between the CARD and the severity of disease or fracture displacement (mild/moderate/severe).

RESULTS

The CARD showed excellent intra- and interobserver reliability. The volar radius measurement method was superior to the midaxis method and was, therefore, used for the second portion of the study. The mean CARD for normal, fractured, and RA wrists was significantly different (2.2 ± 2.5 mm, 15.7 ± 6.5 mm and 0.2 ± 4.4 mm, respectively). There was a strong side-to-side correlation in normal wrists (r = 0.77) and a significant correlation between the CARD (mm) and the severity of deformity (RA, r = -0.7; DRF, r = 0.8).

CONCLUSION

The CARD is a reproducible, easy-to-use measurement of sagittal carpal alignment with a strong side-to-side correlation. The CARD increases with dorsal angulation of the distal radius and decreases as severity of deformity with RA increases.

CLINICAL RELEVANCE

The correlation of the CARD with severity of deformity in DRFs and RA makes it a useful method of assessing deformities in the sagittal plane. The normal wrist can be used as a comparison when evaluating the CARD in the setting of unilateral wrist disease.

An In Vitro Study to Determine the Effect of Ulnar Shortening on Distal Forearm Loading During Wrist and Forearm Motion: Implications in the Treatment of Ulnocarpal Impaction

PURPOSE

To evaluate the effect of ulnar shortening on distal forearm loading following simulated dynamic motion.

METHODS

Ulnar shortening was simulated using a custom-built adjustable implant to simulate up to 4 mm of ulnar shortening (-4 mm) in 9 cadaveric extremities. Load cells were placed in the distal ulna and radius to quantify axial loading. Using a wrist and forearm motion simulator, absolute and percentage loads were measured during dynamic flexion, ulnar deviation (UD), flexion dart throw (DT), and pronation.

RESULTS

There was a significant decrease in absolute and percentage distal ulnar loads at each interval of ulnar shortening during flexion, UD, DT, and pronation. The distal ulna bore no compressive loads, and in fact, tensile loads were measured in the ulna at 2 mm of ulnar shortening during DT and pronation, at 3 mm during flexion, and at 4 mm during UD.

CONCLUSIONS

A progressive decrease in distal ulnar loads with generation of tensile loads was observed with sequential ulnar shortening.

CLINICAL RELEVANCE

Ulnar shortening greater than 2 mm can result in tensile loading in the distal ulna. When managing ulnar impaction syndrome, excessive shortening may not be required to provide relief of symptoms.

Effect of Radial Lengthening on Distal Forearm Loading Following Simulated In Vitro Radial Shortening During Simulated Dynamic Wrist Motion

PURPOSE

To evaluate the effect of radial length change on distal forearm loading during simulated dynamic wrist motion.

METHODS

A custom-built adjustable radial implant was used to simulate up to 4 mm of distal radius shortening (-4 mm) and 3 mm of lengthening (+3 mm). Load cells were placed in the distal radius and ulna in cadavers to measure their respective axial loads. The specimens were mounted on a wrist motion simulator that produced active wrist motion via tendon actuation. To simulate radial lengthening osteotomy following radial shortening from malunion, the radius was sequentially lengthened by 1-mm intervals from -4 mm to +3 mm. Radial and ulnar loads were measured during simulated wrist flexion, ulnar deviation (UD), and flexion dart throw (DT) at each interval of radial lengthening up to +3 mm.

RESULTS

During wrist flexion and UD, for each millimeter of radial lengthening from -4 mm to the native length, there was a significant increase in distal radial loads. No significant change in radial load was observed beyond the native length during flexion and UD. There was no change in distal radial loads during DT for each interval of radial lengthening from -4 mm to +3 mm. A sequential decrease in ulnar loads was observed as the radius was lengthened from -4 mm to +3 mm for all wrist motions evaluated.

CONCLUSIONS

Radial lengthening beyond the native length was not detrimental to radial loading and further reduced distal ulnar loading; achieving at least native ulnar variance seems to be appropriate to restore normal biomechanical loading based on this in vitro study.

CLINICAL RELEVANCE

Lengthening of the radius beyond native variance in the setting of ulnar impaction syndrome, distal radius malunion, or distal radioulnar instability may not result in excessive loading of the distal radius and further reduces loading on the distal ulna. Surgeons should obtain contralateral wrist x-rays to serve as a template when performing distal radius osteotomies.

The Effect of Distal Radius Fracture Location on Distal Radioulnar Joint Stability: A Cadaveric Study

PURPOSE

To investigate whether the location of distal radius osteotomy/shortening relative to the radial insertion of the distal interosseous membrane (DIOM) is correlated with distal radioulnar joint (DRUJ) instability. We hypothesized that distal radius osteotomy and shortening proximal to the DIOM insertion would result in increased DRUJ instability because of induced laxity in the DIOM.

METHODS

Osteotomies of the distal radius were performed proximal and distal to the DIOM insertion in 14 fresh-frozen cadaveric specimens. Using a volar plate, 5 conditions were tested: anatomical radius alignment; 2- and 4-mm shortening at the proximal osteotomy site; and 2- and 4-mm shortening at the distal osteotomy site. Basilar ulnar styloid osteotomy was performed to simulate triangular fibrocartilage complex (TFCC) detachment-specimens were tested with the ulnar styloid detached and the ulnar styloid fixed (to restore normal anatomy). The DRUJ stability was quantified using dorsal-volar displacement of the radius in response to 20 N of force using a force-displacement probe in neutral, pronation, and supination. Posttesting specimen dissections assessed DIOM and distal oblique bundle (DOB) anatomy. The DRUJ stability in each experimental condition was compared with a multifactor repeated measures analysis of variance with the specimen treated as the repeated factor.

RESULTS

There were no significant differences in dorsal-volar translation of the radius (ie, DRUJ stability) between radial osteotomy/shortening proximal and distal to the DIOM insertion, regardless of forearm rotational position or magnitude of shortening. Five (36%) of the 14 specimens had a DOB present. There was a significant increase in DRUJ instability in the setting of TFCC detachment (via basilar ulnar styloid osteotomy).

CONCLUSIONS

No difference in DRUJ stability was observed between distal radius osteotomy/shortening proximal and distal to the DIOM radial insertion, regardless of forearm rotation, magnitude of shortening, and/or TFCC detachment.

CLINICAL RELEVANCE

Distal radius osteotomy and shortening did not affect DRUJ stability regardless of location relative to the DIOM insertion.

The Effect of Dorsal Angulation on Distal Radioulnar Joint Arthrokinematics Measured Using Intercartilage Distance

Background  The effects of dorsal angulation deformity on in vitro distal radioulnar joint (DRUJ) contact patterns are not well understood. Purpose  The purpose of this study was to utilize intercartilage distance to examine the effects of forearm rotation angle, distal radius deformity, and triangular fibrocartilage complex (TFCC) sectioning on DRUJ contact area and centroid position. Methods  An adjustable implant permitted the creation of simulated intact state and dorsal angulation deformities of 10, 20, and 30 degrees. Three-dimensional cartilage models of the distal radius and ulna were created using computed tomography data. Using optically tracked motion data, the relative position of the cartilage models was rendered and used to measure DRUJ cartilage contact mechanics. Results  DRUJ contact area was highest between 10 and 30 degrees of supination. TFCC sectioning caused a significant decrease in contact area with a mean reduction of 11 ± 7 mm ² between the TFCC intact and sectioned conditions across all variables. The position of the contact centroid moved volarly and proximally with supination for all variables. Deformity had a significant effect on the location of the contact centroid along the volar-dorsal plane. Conclusion  Contact area in the DRUJ was maximal between 10 and 30 degrees of supination during the conditions tested. There was a significant effect of simulated TFCC rupture on contact area in the DRUJ, with a mean contact reduction of 11 ± 7 mm ² after sectioning. Increasing dorsal angulation caused the contact centroid to move progressively more volar in the sigmoid notch.

Effect of decrease in radial inclination of distal radius fractures on distal radioulnar joint stability: a biomechanical study

We investigated the relationship between the radial inclination of the distal radius and distal radioulnar joint stability. Six fresh-frozen upper extremities were used. Radial inclination was decreased by 10° and 20° and increased by 10° from the original radial inclination. Distal radioulnar joint stiffness was assessed with an intact radioulnar ligament and after partial and then complete sectioning of the radioulnar ligament. Radial angulation deformities significantly increased distal radioulnar joint stiffness when the radioulnar ligament is totally or partially attached to the ulnar fovea. After complete sectioning of the radioulnar ligament, distal radioulnar joint stiffness decreased significantly; additional radial angulation deformity slightly increased distal radioulnar joint stiffness, but the distal radioulnar joint never recovered to the original stiffness. Based on the results, radial angulation deformities of the distal radius should be corrected within 10° when the radioulnar ligament is intact, to reduce the risk of symptomatic distal radioulnar joint instability.

Lift-Off Screw Results in Accurate Sagittal Tilt Correction in a Distal Radius Fracture Model

PURPOSE

To determine the accuracy of a distal-first open reduction internal plate fixation technique in achieving correction of volar tilt in dorsally angulated distal radius fractures.

METHODS

Twenty foam radius models were divided evenly into groups N (normal) and O (osteoporotic). Dorsally angulated extra-articular distal radius fractures were then created. Group O underwent further modification to simulate an osteoporotic model. After static pinning in various degrees of dorsal angulation, opaque fiducial markers were placed and fluoroscopy was used to measure prereduction volar tilt. A variation of the distal-first plate application technique was used where a lift-off screw (LOS) was placed in the proximal most locking hole and propped the proximal aspect of the plate by the screw's length. The LOS length corresponded to the volar tilt correction needed. After fracture reduction using this technique, we measured the volar tilt again. We then compared the actual volar tilt correction with what was predicted based on the LOS length used. We also compared the tilt correction accuracy in the normal and osteoporotic models.

RESULTS

Prereduction tilt ranged from 3° to 52° of dorsal tilt from normal (10° volar tilt). Corresponding LOSs ranged from 5 to 42 mm in length. Tilt correction correlated with screw length in a linear fashion (R = 0.9). The mean difference between actual and predicted tilt correction for a given screw length was 0.5° ± 3.0°, and the mean absolute difference was 2.4° ± 1.7° for all specimens. There was no difference between normal and osteoporotic models.

CONCLUSIONS

Prereduction dorsal tilt can be accurately corrected within a few degrees of the goal by using the distal-first technique with an LOS. The LOS length can be calculated, and this technique can potentially be used with any distal radius periarticular locking plate with locking options in the shaft.

CLINICAL RELEVANCE

A technique that provides accurate tilt correction would be of benefit to surgeons treating distal radius fractures with volar plates.

Preoperative Computer Simulation and Patient-specific Guides are Safe and Effective to Correct Forearm Deformity in Children

BACKGROUND

Posttraumatic and congenital forearm deformities in children can be difficult to appreciate in all planes. In cases of distal radioulnar joint instability and loss of forearm rotation, surgical correction is challenging. Advances in 3-dimensional printing allow creation of custom guides at a reasonable cost, enabling precise correction of the deformity in all planes.

METHODS

Nineteen children with deformity of the forearm had corrective osteotomies performed using preoperative 3-dimensional computer modeling and patient-specific surgical guides. Surgicase software was used for 3-dimensional planning of the corrective osteotomy, by superimposing a mirror image of the unaffected side as a template. Based upon this planning, patient-specific surgical guides were manufactured. Radiographic and clinical outcomes were assessed.

RESULTS

Three patients had a diagnosis of multiple hereditary exostoses, and one of Madelung's deformity. The remaining 15 patients had a diagnosis of fracture malunion. Average preoperative angulation of both the radius and ulna was 23 degrees. For the patients with fracture malunions, the time from injury to surgery ranged from 6 months to 8 years. Twelve patients underwent osteotomies of both the radius and ulna, 5 had osteotomies of the radius alone, and 2 had a single osteotomy of the ulna only. All osteotomies went on to unite and no patient lost range of motion. Preoperative arc of forearm rotation averaged 101 degrees (range 0 to 180 degrees). Postoperatively, this improved to 133 degrees (range 85 to 180 degrees). Eight patients had distal radioulnar instability preoperatively, all of which normalized after surgery. There were 4 complications: 1 hypertrophic scar, 1 subject with extensor pollicis longus weakness, and 2 transient sensory losses in the superficial radial nerve distribution.

CONCLUSIONS

This case series demonstrates that 3-dimensional computer modeling permits complex and multiple osteotomies to be done safely to achieve deformity correction in children. Limitations in forearm rotation and distal radioulnar malalignment can be reliably improved using this technique.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

The effects of wrist motion and hand orientation on muscle forces: A physiologic wrist simulator study

Although the orientations of the hand and forearm vary for different wrist rehabilitation protocols, their effect on muscle forces has not been quantified. Physiologic simulators enable a biomechanical evaluation of the joint by recreating functional motions in cadaveric specimens. Control strategies used to actuate joints in physiologic simulators usually employ position or force feedback alone to achieve optimum load distribution across the muscles. After successful tests on a phantom limb, unique combinations of position and force feedback – hybrid control and cascade control – were used to simulate multiple cyclic wrist motions of flexion-extension, radioulnar deviation, dart thrower’s motion, and circumduction using six muscles in ten cadaveric specimens. Low kinematic errors and coefficients of variation of muscle forces were observed for planar and complex wrist motions using both novel control strategies. The effect of gravity was most pronounced when the hand was in the horizontal orientation, resulting in higher extensor forces (p < 0.017) and higher out-of-plane kinematic errors (p < 0.007), as compared to the vertically upward or downward orientations. Muscle forces were also affected by the direction of rotation during circumduction. The peak force of flexor carpi radialis was higher in clockwise circumduction (p = 0.017), while that of flexor carpi ulnaris was higher in anticlockwise circumduction (p = 0.013). Thus, the physiologic wrist simulator accurately replicated cyclic planar and complex motions in cadaveric specimens. Moreover, the dependence of muscle forces on the hand orientation and the direction of circumduction could be vital in the specification of such parameters during wrist rehabilitation.

Distal radioulnar joint: functional anatomy, including pathomechanics

The distal radioulnar joint allows the human to rotate the forearm to place the hand in a desired position to perform different tasks, without interfering with the grasping function of the hand. The ulna is the stable part of the forearm around which the radius rotates; the stability of the distal radioulnar joint is provided by the interaction between ligaments, muscles and bones. The stabilizing structures are the triangular fibrocartilage complex, the ulnocarpal ligament complex, the extensor carpi ulnaris tendon and tendon sheath, the pronator quadratus, the interosseous membrane and ligament, the bone itself and the joint capsule. The purpose of this review article is to present and illustrate the current understanding of the functional anatomy and pathomechanics of this joint.

Current Trends in the Management of Distal Radius Fractures

This article discusses recent reports on distal radius fractures. The keyword "distal radius fracture" was used to query the PubMed database of the US National Library of Medicine. From the resulting list, articles published in the Journal of Hand Surgery (American Volume), the Journal of Hand Surgery (European Volume), and the Journal of Orthopaedic Trauma from April 2014 through December 2015 were reviewed. Related commentaries were also evaluated. Case series of fewer than 5 patients were excluded. The 65 studies and commentaries identified are categorized and summarized. [Orthopedics. 2017; 40(3):145-152.].

The ulnar side of the wrist: Clinically relevant anatomy and biomechanics

BACKGROUND

In the hectic environment of a hand therapy clinic, the opportunity to carefully consider the relationships among pathology, pathomechanics, surgical repair techniques, tissue healing, postoperative management, and rehabilitation program development and progression is limited. Clinicians often default to seeking a protocol, a recipe to follow.

OBJECTIVES

Using the ulnar side of the wrist as an example, relevant anatomy and biomechanics are directly related to several commonly seen pathologies, including fractures, ligament injuries, and instability.

CONCLUSION

Armed with knowledge of anatomy, biomechanics, and surgical procedures, the need for a protocol disappears. Each patient can be individually managed according to his or her unique set of variables and responses to injury, repair, healing, and recovery of function.

Control of a wrist joint motion simulator: A phantom study

The presence of muscle redundancy and co-activation of agonist-antagonist pairs in vivo makes the optimization of the load distribution between muscles in physiologic joint simulators vital. This optimization is usually achieved by employing different control strategies based on position and/or force feedback. A muscle activated physiologic wrist simulator was developed to test and iteratively refine such control strategies on a functional replica of a human arm. Motions of the wrist were recreated by applying tensile loads using electromechanical actuators. Load cells were used to monitor the force applied by each muscle and an optical motion capture system was used to track joint angles of the wrist in real-time. Four control strategies were evaluated based on their kinematic error, repeatability and ability to vary co-contraction. With kinematic errors of less than 1.5°, the ability to vary co-contraction, and without the need for predefined antagonistic forces or muscle force ratios, novel control strategies - hybrid control and cascade control - were preferred over standard control strategies - position control and force control. Muscle forces obtained from hybrid and cascade control corresponded well with in vivo EMG data and muscle force data from other wrist simulators in the literature. The decoupling of the wrist axes combined with the robustness of the control strategies resulted in complex motions, like dart thrower׳s motion and circumduction, being accurate and repeatable. Thus, two novel strategies with repeatable kinematics and physiologically relevant muscle forces are introduced for the control of joint simulators.

Optimal Positioning for Volar Plate Fixation of a Distal Radius Fracture: Determining the Distal Dorsal Cortical Distance

Distal radius fractures are currently among the most common fractures of the musculoskeletal system. With a population that is living longer, being more active, and the increasing incidence of osteoporosis, these injuries will continue to become increasingly prevalent. When operative fixation is indicated, the volar locking plate has recently become the treatment of choice. However, despite its success, suboptimal position of the volar locking plate can still result in radiographic loss of reduction. The distal dorsal cortical distance is being introduced as an intraoperative radiographic tool to help optimize plate position and minimize late loss of fracture reduction.

Effect of Volarly Angulated Distal Radius Fractures on Forearm Rotation and Distal Radioulnar Joint Kinematics

PURPOSE

To examine the effect of volar angulation deformities of the distal radius with and without triangular fibrocartilage complex (TFCC) rupture on forearm range of motion and the kinematics of the ulnar head at the distal radioulnar joint (DRUJ) during simulated active forearm rotation.

METHODS

Volar angulation deformities of the distal radius with 10° and 20° angulation from the native orientation were created in 8 cadaveric specimens using an adjustable apparatus. Active supination and pronation were performed using a forearm motion simulator. Pronation and supination range of motion was quantified with each deformity. In addition, changes in the dorsovolar position of the ulnar head relative to the radius were calculated after simulating each distal radial deformity. Testing was performed with the TFCC intact and sectioned.

RESULTS

Volar angulation deformities of 20° decreased the supination range with preservation of pronation. There was no effect of TFCC status on the range of forearm rotation. With the TFCC intact, volar angulation deformities translated the ulna slightly dorsally in pronation and volarly in supination. After sectioning the TFCC, volar angulation deformities of 10° and 20° translated the ulna dorsally throughout forearm rotation.

CONCLUSIONS

Volar angulation deformities reduce supination range and alter the DRUJ kinematics. The increased tension in the intact TFCC caused by volar angulation deformities likely prevented the expected dorsovolar displacement at the DRUJ and restricted supination. Dividing the TFCC released the constraining effect on the DRUJ and allowed the ulna to translate dorsally. However, supination remained limited, presumably because of impediment from the dorsally subluxated ulna.

CLINICAL RELEVANCE

This study demonstrated the importance of correcting volar angulation deformities of the distal radius to less than 20° in order to maintain normal range of forearm rotation and to less than 10° to maintain normal DRUJ kinematics when the TFCC is ruptured.

In Vivo Contact Characteristics of Distal Radioulnar Joint With Malunited Distal Radius During Wrist Motion

PURPOSE

To determine whether distal radioulnar joint (DRUJ) contact characteristics were altered in patients with malunited distal radius fractures.

METHODS

We obtained computed tomography scans at 5 positions of both wrists of 6 patients who had unilateral malunited distal radius fractures with dorsal angulation from 10° to 20° and ulnar variance less than 3 mm. We reconstructed 3-dimensional images and mapped contact regions of DRUJ by calculating the shortest distance between the 2 opposing bones. The contact areas of the DRUJ were measured and the contact region centers were calculated and analyzed. The values of the malunited side were compared with those of the contralateral uninjured side.

RESULTS

In the uninjured wrist, the contact areas of the DRUJ increased slightly from wrist flexion to extension and ulnar deviation. In the malunited wrist, we found the contact areas of DRUJ to be progressively reduced from 20° flexion to neutral, 40° extension, and 20° extension, to ulnar deviation. The centroid of this area on the sigmoid notch moved to distal from flexion to extension. Compared with the contralateral uninjured wrist, the contact area significantly decreased during wrist extension and ulnar deviation, and significantly increased during wrist flexion. The centroids of this area on sigmoid notch all moved volarly in all selected wrist positions.

CONCLUSIONS

The contact areas of the DRUJ and the centroid of contact area on sigmoid notch are altered in patients with malunited distal radius fractures. The contact area of the DRUJ increases during wrist flexion and decreases during wrist extension and ulnar deviation. The centroids of the contact area on sigmoid notch move volarly during wrist flexion-extension and ulnar deviation.

CLINICAL RELEVANCE

The in vivo findings suggest that alterations in joint mechanics may have an important role in the dysfunction associated with these injuries.

Effect of volar angulation of extra-articular distal radius fractures on distal radioulnar joint stability: a biomechanical study

The relationship between increased volar tilt of the distal radius and distal radioulnar joint stability was examined. Distal radioulnar joint stiffness was recorded at 10° intervals from 10° dorsal angulation to 20° of volar angulation from the anatomical position of the radius. Tests were performed with the intact radioulnar ligament and repeated after partial and then complete sectioning of the radioulnar ligament at the ulnar fovea. With the intact radioulnar ligament, distal radioulnar joint stiffness increased significantly at 10° and 20° of volar angulation. Partial sectioning of the radioulnar ligament resulted in an approximate 10% decrease of distal radioulnar joint stiffness compared with the intact state, but distal radioulnar joint stiffness still increased significantly with greater volar tilt. Complete sectioning of the radioulnar ligament significantly decreased distal radioulnar joint stiffness, and increasing the volar tilt did not result in increased distal radioulnar joint stiffness. These results suggest that volar angulation deformities of the distal radius should be corrected to 10° of volar tilt when the triangular fibrocartilage complex is intact. Level of evidence: N/A.

Volar subluxation of the ulnar head in dorsal translation deformities of distal radius fractures: an in vitro biomechanical study

OBJECTIVES

To quantify the effects of dorsal translation deformities of the distal radius with and without dorsal angulation on volar displacement of the ulnar head during simulated active forearm rotation, both with the triangular fibrocartilage complex (TFCC) intact and sectioned conditions.

METHODS

Eight fresh-frozen cadaveric upper extremities were mounted in an active forearm motion simulator, and distal radial deformities of 0, 5, and 10 mm of dorsal translation with 0, 10, 20, and 30 degrees of dorsal angulation were simulated. Volar displacement of the ulnar head at the distal radioulnar joint as a result of each distal radial deformity was quantified during simulated active supination. The data were collected with the TFCC intact and after sectioning the TFCC at its ulnar insertion.

RESULTS

Increasing isolated dorsal translation deformities increased volar displacement of the ulnar head when the TFCC was intact (P < 0.001). Increasing dorsal translation combined with dorsal angulation increased volar displacement of the ulnar head compared with isolated dorsal angulation deformities (P < 0.001). Sectioning the TFCC increased the volar displacement of the ulnar head caused by each distal radial deformity (P = 0.001).

CONCLUSIONS

These results emphasize the clinical importance of evaluating the magnitude of both dorsal translation and dorsal angulation when managing displaced distal radius fractures and malunions.