Quantification of the radial torsion angle with computerized tomography in cadaver specimens

Radiographic Comparison of Forearm Symmetry in Healthy Individuals and Its Importance in the Diagnosis of Longitudinal Radioulnar Dissociation

PURPOSE

Longitudinal radioulnar dissociation (LRD) is an injury often missed upon initial presentation. A recent study examined a radiographic screening test in cadavers that showed increased interosseous distance when the interosseous ligament (IOL) was divided. For this test to be clinically useful, it is necessary for uninjured forearms to have similar interosseous spaces. The purpose of this study was to determine the typical differences between right and left interosseous spaces of healthy individuals.

METHODS

Anterior-posterior x-rays of bilateral forearms in maximum supination of 28 surgical residents with no history of injury were obtained. These images were uploaded into a picture archiving and communication system and then digitized. The length of the radius was measured (Xr). The maximum interosseous distance (Dmax) between the radius and ulna as well as the interosseous distance at a location 0.3 Xr from the distal radioulnar joint was measured. The right and left arm distances were compared. Also, an outlier analysis was used to evaluate forearm rotational asymmetry between right and left arms.

RESULTS

The outlier analysis revealed two sets of forearm x-rays were rotationally different compared to the rest of the group due to asymmetric arm positioning; these data were excluded from the analysis. The average difference in Dmax was 1.7 mm (standard deviation [SD] 1.5) between right and left arms, and this was found at a position of 0.28 Xr on average. The difference in interosseous distance measured at a fixed location 0.3 Xr was 1.6 mm (SD 1.5). No significant difference was found between the paired right and left arms for Dmax or at 0.3 Xr.

CONCLUSIONS

There does not appear to be any significant difference between the maximum interosseous distance of right and left arms in healthy individuals. Therefore, analyzing bilateral forearm x-rays may be a simple LRD screening test.

CLINICAL RELEVANCE

Understanding the degree of normal variation in the forearm bone spacing might inform evaluation of abnormal forearm bone alignment resulting from LRD.

Bilateral symmetry assessment of healthy forearm kinematics using 4D-CT

Advanced stage distal radio-ulnar joint (DRUJ) injury may warrant radius corrective osteotomy or arthroplasty. These procedures aim to restore geometry, function and kinematics and could benefit from preoperative planning where the contralateral forearm is typically used as reference. Natural variations regarding geometry and function between forearms are known but kinematic differences are not. This work aimed to quantify bilateral differences in forearm kinematics. Consequently, 4D-CT data of ten healthy volunteers was acquired, imaging motion of both forearm joints. Segmentation and registration of the radius and ulna bones resulted in a 3D representation of forearm rotation. Subsequently, the forearm rotation axis, radius translation along the ulna and radius rotation around its own inertial axis were calculated. The rotation axis of the right arm was mirrored to set up a comparison with the left arm. All other differences were calculated directly. The mean angle and distance between forearm rotation axes were 0.6° and 0.8 mm. The mean difference in radius translation along the ulna was 0.9 mm. On average, radius rotation around the radius' inertial axis differed 2.6°, between forearms. This study's findings can benefit DRUJ surgery preoperative planning and postoperative kinematic evaluation. Level of evidence: IV.

Acceptable range of forearm deformity derived from relation to three-dimensional analysis and clinical impairments

This study aimed to investigate deformity patterns that cause clinical impairments and determine the acceptable range of deformity in the treatment of forearm diaphyseal fractures. A three-dimensional (3D) deformity analysis based on computed bone models was performed on 39 patients with malunited diaphyseal both-bone forearm fractures to investigate the 3D deformity patterns of the radius and ulna at the fracture location and the relationship between 3D deformity and clinical impairments. Clinical impairments were evaluated using forearm motion deficit. Cutoff values of forearm deformities were calculated by performing receiver operating characteristic analysis using the deformity angle and the limited forearm rotation range of motion (less than 50° of pronation or supination) resulting in activities of daily living (ADL) impairment as variables. The extension, varus, and pronation deformities most commonly occurred in the radius, whereas the extension deformity was commonly observed in the ulna. A positive correlation was observed between pronation deficit and extension deformity of the radius (R = 0.41) and between supination deficit and pronation deformity of the ulna (R = 0.44). In contrast, a negative correlation was observed between pronation deficit and pronation deformity of the radius (R = -0.44) and between pronation deficit and pronation deformity of the ulna (R = -0.51). To minimize ADL impairment, radial extension deformity should be <18.4°, radial rotation deformity <12.8°, and ulnar rotation deformity <16.6°. The deformities in the sagittal and axial planes of the radius and in the axial plane of the ulna were responsible for the limited forearm rotation.

Developmental Anatomy of the Radial Bow in Pediatric Patients Using 3D Imaging

BACKGROUND

While radial bow shape is well characterized in adults, its development in children is not well understood. Previous studies on the radial bow use radiographs, thus, rotational positioning of the forearm could alter bowing measurements. This study used 3D imaging to better assess the pediatric radial bow.

METHODS

Computed tomography scans from the New Mexico Decedent Image Database were obtained for ages 2 to 16 (females) and 18 (males) (n=152). 3D models were generated using Slicer and Rhino software. Length of the entire radial bow (bicipital tuberosity to sigmoid notch), maximum radial bow, location of the maximum radial bow (bicipital tuberosity to the point of maximum bowing), and distal, middle, and proximal third radial bows were measured.

RESULTS

The length of the entire bow increased with age, with a strong correlation with age ( r =0.90, P <0.01). The maximum bow increased with age, with a strong correlation with age ( r =0.78, P <0.01). The maximum bow normalized to the length of the entire bow increased mildly with age, mean 0.059 ± 0.012 ( r =0.24, P =0.0024), but seems to plateau around age 8. The location of the maximum bow increased with age ( r =0.85, P <0.01). The normalized location of the maximum bow remained constant between ages, with a mean of 0.41 ± 0.10 ( r =0.12, P =0.14). The normalized distal third bow mildly increased with age ( r =0.34, P <0.01), the normalized middle third bow mildly increased with age ( r =0.25, P <0.01), and the normalized proximal third bow remained constant between ages ( r =0.096, P =0.24).

CONCLUSIONS

Normalized values for maximum, distal third, and middle third radial bow increase with age, while normalized values for location and proximal third radial bow remain relatively constant, suggesting the proportional shape of the radius changes during development, although qualitatively plateaus after age 8.

LEVEL OF EVIDENCE

Retrospective comparative study, Level-III.

Malunion of Pediatric Forearm Shaft Fractures: Management Principles and Techniques

PURPOSE OF REVIEW

Clinically significant malunion of forearm diaphyseal fractures is an uncommon but potentially disabling condition amongst children and adolescents. We present the preoperative evaluation, including imaging, and discuss surgical indications and contemporary approaches to manage such patients, including an illustrative case.

RECENT FINDINGS

While advances in three-dimensional (3D) simulation, modeling, and patient-specific instrumentation have expanded the surgical armamentarium, their impact on long-term outcomes compared to traditional methods remains unknown. Successful outcome following surgical correction of malunion following a both-bone forearm fracture can be achieved with careful patient selection, appropriate indications, and a well-planned surgical execution.

Morphological symmetry of the radius and ulna-Can contralateral forearm bones utilize as a reliable template for the opposite side?

The most important precondition for correction of the affected forearm using data from the contralateral side is that the left and right bone features must be similar, in order to develop patient-specific instruments (PSIs) and/or utilize computer-assisted orthopedic surgery (CAOS). The forearm has complex anatomical structure, and most people use their dominant hand more than their less dominant hand, sometimes resulting in asymmetry of the upper limbs. The aim of this study is to investigate differences of the bilateral forearm bones through a quantitative comparison of whole bone parameters including length, volume, bowing, and twisting parameters, and regional shape differences of the forearm bones. In total, 132 bilateral 3D radii and ulnae 3D models were obtained from CT images, whole bone parameters and regional shape were analyzed. Statistically significant differences in whole bone parameters were not shown. Regionally, the radius shows asymmetry in the upper section of the central part to the upper section of the distal part. The ulna shows asymmetry in the lower section of the proximal part to the lower section of the central part. Utilizing contralateral side forearm bones to correct the affected side may be feasible despite regional differences in the forearm bones of around 0.5 mm.

Effectiveness Assessment of CAD Simulation in Complex Orthopedic Surgery Practices

This experimental study defines the usage of a computer-aided surgical simulation process that is effective, safe, user-friendly, and low-cost, that achieves a detailed and realistic representation of the anatomical region of interest. The chosen tools for this purpose are state-of-the-art Computer Aided Design (CAD) software for mechanical design, and are the fundamental application dedicated to parametric modeling. These tools support different work environments, each one is for a specific type of modeling, and they allow the simulation of surgery. The result will be a faithful representation of the anatomical part both before and after the surgical procedure, screening all the intermediate phases. The doctor will assess different lines of action according to the results, then he will communicate them to the engineer who, consequently, will correct the antisymmetric issue and regenerate the model. Exact measurements of the mutual positions of the various components, skeletal and synthetic, can be achieved; all the osteosynthesis tools, necessary for the surgeon, can be included in the project according to different types of fracture to perfectly match the morphology of the bone to be treated. The method has been tested on seven clinical cases of different complexity and nature and the results of the simulations have been found to be of great effectiveness in the phase of diagnosis and of preoperative planning for the doctors and surgeons; therefore, allowing a lower risk medical operation with a better outcome. This work delivers experimental results in line with theoretical research findings in detail; moreover, full experimental and/or methodical details are provided, so that outcomes could be obtained.

Rotational Anatomy of the Radius and Ulna: Surgical Implications

PURPOSE

The rotational anatomy of the forearm bones is not well defined. This study aims to further the understanding of the torsion of the radius and ulna to better guide treatment.

METHODS

Computed tomography images of 98 cadaveric forearms were obtained and 3-dimensional models of the radius and ulna were generated and analyzed. The rotation of the radius was evaluated by comparing the orientation of the distal radius central axis (DRCA) with the volar cortex of the distal radius (DR) and biceps tuberosity (BT). The rotation of the ulna was evaluated by assessing the orientation of the ulnar head with respect to the proximal ulna.

RESULTS

The DR volar cortex pronates from distal to proximal. The BT was 43.8° ± 16.9° supinated from the DRCA (range, 2.7°-86.5°). The mean difference in rotation between contralateral biceps tuberosities was 7.0° ± 7.1°. The volar cortex of the DR was 12.6° ± 5.4° supinated compared with the DRCA. The ulnar head was pronated 8.4° ± 14.9° with respect to the greater sigmoid notch (range, 50.3° pronation-22.0° supination).

CONCLUSIONS

The BT has a variable orientation relative to the DR, but it is generally located anteromedially in a supinated arm or 136° opposite the radial styloid. Understanding the rotational anatomy of the radius and ulna can play an important role in surgical planning and implant design. The rotational anatomy of the radius and ulna varies significantly between individuals, but is similar in contralateral limbs.

CLINICAL RELEVANCE

Distal radius volar cortex rotational anatomy can help guide treatment of DR fractures and malunions as well as assist in positioning of wrist arthroplasty implants, particularly in the presence of bone loss. The side-to-side similarities demonstrated in this study should be helpful in managing patients with segmental bone loss or fracture malunion and those requiring joint reconstruction.

An Easy and Economical Way to Produce a Three-Dimensional Bone Phantom in a Dog with Antebrachial Deformities

Simple Summary

Accurate planning, for corrective surgeries in case of bone cutting, is necessary to obtain a precise coordination of the skeleton and to achieve the owner’s satisfaction. The present experiment displays a simple and cost-effective technique for surgical planning, utilizing a 3-D bone phantom model in a dog with foreleg deformity.

Abstract

3-D surgical planning for restorative osteotomy is costly and time-consuming because surgeons need to be helped from commercial companies to get 3-D printed bones. However, practitioners can save time and keep the cost to a minimum by utilizing free software and establishing their 3-D printers locally. Surgical planning for the corrective osteotomy of antebrachial growth deformities (AGD) is challenging for several reasons (the nature of the biapical or multiapical conformational abnormalities and lack of a reference value for the specific breed). Pre-operative planning challenges include: a definite description of the position of the center of rotation of angulation (CORA) and proper positioning of the osteotomies applicable to the CORA. In the present study, we demonstrated an accurate and reproducible bone-cutting technique using patient-specific instrumentations (PSI) 3-D technology. The results of the location precision showed that, by using PSIs, the surgeons were able to accurately replicate preoperative resection planning. PSI results also indicate that PSI technology provides a smaller standard deviation than the freehand method. PSI technology performed in the distal radial angular deformity may provide good cutting accuracy. In conclusion, the PSI technology may improve bone-cutting accuracy during corrective osteotomy by providing clinically acceptable margins.

[Special aspects of fractures of the distal forearm]

BACKGROUND

Fractures of the distal forearm, especially fractures of the distal radius which are the most common fracture in humans, are of increasing socioeconomic relevance due to the increasing incidence and the increasing costs that are associated with the popularity of palmar plating.

OBJECTIVES

Radiological imaging for diagnosis and follow-up are presented with special focus on new biomechanical fracture concepts such as the four-corner concept.

MATERIALS AND METHODS

The basic literature and expert opinions are evaluated and discussed.

RESULTS

In intra-articular fractures of the distal radius, plain radiographs must be supplemented by computed tomography (CT). Direct CT arthrography allows not only analysis of the fracture pattern, but also detection of accompanying injuries of the carpus, especially the scapholunate ligament, and the ulnocarpal complex. The plain radiographs should also be analyzed for accompanying injuries. Therefore, both acquisition of the imaging data and their morphometrical analysis have to be standardized.

CONCLUSIONS

In addition to diagnosis and follow-up, radiological imaging plays a decisive role in the treatment of distal forearm fractures. CT and direct CT arthrography have become important tools in intra-articular distal radius fractures.

Assessing distal radius malrotation following fracture using computed tomography

HYPOTHESIS

When the distal fracture fragment in distal radius fractures displaces, it commonly rotates as well as shortens and angulates.

AIM

The aim of this study was to assess the frequency and magnitude of malrotation of the distal fracture fragment using computed tomography (CT).

METHODS

A retrospective radiological assessment of 85 CT scans of the distal radius, 35 following fracture and 50 normal radii, was carried out. We developed and applied a simple method for measuring rotation of the distal radius relative to the diaphysis using routine CT scans of the wrist. A Mann-Whitney analysis was used to identify differences in radial rotation between fractures and controls. Intra- and inter-observer reliability were analyzed using intra-class correlation coefficients (ICCs) and Bland-Altman plots.

RESULTS

The articular surface of the distal radius is normally rotated in the long axis of the forearm relative to the diaphysis, either into pronation or into supination. The median radial rotation angle of controls was 1° pronation (range -15° to 4°) compared to 3° pronation (range -24° to 31°) in the fracture group. The absolute rotation angle was significantly greater in the fracture group (median 10°, range 0-31° vs. 3°, range 0-15°; p < 0.001) and outside the "normal range" of controls in 26 cases indicating that 75% had rotated appreciably following injury. Intra- and inter-observer reliability of measurements were good with ICCs of 0.99 and 0.98, respectively.

CONCLUSIONS

Malrotation of the distal radius appears common following distal radius fracture. Malrotation of the distal fracture fragment has been shown to affect distal radio-ulnar joint function. Despite this, rotational deformity is rarely addressed in clinical practice as it is difficult to appreciate on simple radiographs. The simplified method described here is easy to use in routine clinical practice and also appears reliable. Measuring radial rotation may be an important consideration when planning both primary treatment and corrective osteotomy for patients with distal radial malunion.

A cadaveric study of radial and ulnar bowing in the sagittal and coronal planes

BACKGROUND

This study provides a comprehensive, full-length assessment of radial and ulnar bowing in anteroposterior (AP) and sagittal planes.

METHODS

Radial and ulnar AP and lateral bowing were assessed using orthogonal digital photographs of 211 randomly selected cadaveric bilateral forearms (422 radius, 422 ulna bones) from a well-preserved osteologic collection.

RESULTS

In the radial AP plane, an apex-radial bow was present at a mean of 58% of bone length (slightly distal to midpoint), with a mean depth of 1.3 cm. In the radial lateral plane, an apex-dorsal bow occurred at a mean of 45% of bone length, with a mean depth of 0.8 cm. In the ulnar AP plane, apex-radial bow occurred at a mean of 32% of bone length with a mean depth of 1.0 cm. In the ulnar lateral plane, the majority of specimens (81%) had an apex-dorsal bow, whereas 19% had a reverse (apex-volar) bow. Lateral ulnar bow was located at a mean of 33% of bone length with a mean depth of 2.0 cm, with 36% of specimens possessing a lateral bow located at 35% or more distal along the ulna. Side-to-side differences for bow location and depth were less than 2% of bone length.

CONCLUSIONS

Ulnar lateral bow was found to be more distal than in previously published works, which analyzed only the proximal ulna, and this study describes a reverse ulnar bow in 19% of specimens. This demonstrates lateral ulnar morphology to be more variable than previously defined with minimal side-to-side variability, which are important considerations for fracture fixation and elbow arthroplasty.

[Posttraumatic torsional deformities of the forearm : Methods of measurement and decision guidelines for correction]

Forearm fractures are common in all age groups. Even if the adjacent joints are not directly involved, these fractures have an intra-articular character. One of the most common complications of these injuries is a painful limitation of the range of motion and especially of pronation and supination. This is often due to an underdiagnosed torsional deformity; however, in recent years new methods have been developed to make these torsional differences visible and quantifiable through the use of sectional imaging. The principle of measurement corresponds to that of the torsion measurement of the lower limbs. Computed tomography (CT) or magnetic resonance imaging (MRI) scans are created at defined heights. By searching for certain landmarks, torsional angles are measured in relation to a defined reference line. A new alternative is the use of 3D reformation models. The presence of a torsional deformity, especial of the radius, leads to an impairment of the pronation and supination of the forearm. In the presence of torsional deformities, radiological measurements can help to decide if an operation is needed or not. Unlike the lower limbs, there are still no uniform cut-off values as to when a correction is indicated. Decisions must be made together with the patient by taking the clinical and radiological results into account.

Best Approaches in Distal Radius Fracture Malunions

PURPOSE OF REVIEW

Malunion remains a common complication in the treatment of distal radius fractures. The purpose of this review was to discuss the various approaches in planning and surgical management for extra- and intra-articular distal radius malunions.

RECENT FINDINGS

Several recent studies have reported good results with surgical correction of distal radius malunions utilizing a number of preoperative planning methods and surgical approaches. Three-dimensional models and custom cutting guides have recently become more popular, but their benefit in comparison to other methods remains unclear. Regardless of preoperative planning method or surgical approach, good results can be achieved with correction of distal radius malunion with careful attention to patient selection, indications, and surgical technique.

Radial torsion in dogs with medial compartment disease

OBJECTIVE

To evaluate the magnitude and direction of radial torsion (RT) in dogs with medial compartment disease (MCD).

STUDY DESIGN

Case-control study.

SAMPLE POPULATION

Twenty-eight healthy dogs and 28 dogs with confirmed MCD.

METHODS

Computed tomography images of each dog's antebrachium were evaluated. Radial torsion was measured by using previously described landmarks on the proximal and distal radius. Differences between groups were tested with Student's t tests and Wilcoxon rank-sum tests.

RESULTS

Healthy dogs had a mean RT angle of 3.44° (range, 1.28°-5.44°). Dogs with MCD had a mean RT angle of 11.84° (range, 2.31°-26.55°). Both groups included similar proportions of dogs with external (76% vs 77%) and internal (24% vs 23%) torsion. The direction of torsion (P = .21 and P = .69) did not appear to affect the magnitude of the RT angle.

CONCLUSION

Dogs with MCD had an increased RT angle compared with healthy controls. The direction of torsion varied similarly between groups regardless of the disease status of dogs in this study.

CLINICAL SIGNIFICANCE

The fourfold increase in the RT seen in dogs with MCD may contribute to the rotational overload proposed recently, potentially modifying the orientation of the elliptical radial head and the ligaments crossing the elbow joint.

Complex angular and torsional deformities (distal femoral malunions)

Objective: To describe the surgical technique of complex distal femoral deformity correction with the aid of stereolithography apparatus (SLA) biomodels, stabilized with locking plate fixation.

Methods: Full-size replica epoxy bone bio-models of the affected femurs (4 dogs/5 limbs) were used as templates for surgical planning. A rehearsal procedure was performed on the biomodels aided by a guide wire technique and stabilized with locking plate fixation. Surgery performed in all dogs was guided by the rehearsal procedure. All pre-contoured implants were subsequently used in the definitive surgical procedure with minimal modification.

Results: All dogs had markedly improved, with near normal functional outcomes; all but one had a mild persistent lameness at the final in-hospital follow-up examination (mean: 54.4 weeks; range: 24–113 weeks after surgery). All femurs healed without complications (mean: 34 weeks, median: 12 weeks; range: 8–12 weeks for closing osteotomies, and 26–113 weeks for opening wedge osteotomies). Long-term follow-up examination (mean: 28.6 months; range: 5–42 months) revealed all but one owner to be highly satisfied with the outcome. Complications were observed in two dogs: prolonged tibiotarsal joint decreased flexion that resolved with physical therapy. In one of these dogs, iatrogenic transection of the long digital extensor tendon was repaired, and the other had a peroneal nerve neurapraxia.

Clinical significance: Stereolithography apparatus biomodels and rehearsal surgery simplified the definitive surgical corrections of complex femoral malunions and resulted in good functional outcomes.

Online supplementary material is available for this paper at: http://dx.doi.org/10.3415/VCOT-15-08-0145

Prediction of normal bone anatomy for the planning of corrective osteotomies of malunited forearm bones using a three-dimensional statistical shape model

Corrective osteotomies of the forearm based on 3D computer simulation using contralateral anatomy as a reconstruction template is an approved method. Limitations are existing considerable differences between left and right forearms, and that a healthy contralateral anatomy is required. We evaluated if a computer model, not relying on the contralateral anatomy, may replace the current method by predicting the pre-traumatic healthy shape. A statistical shape model (SSM) was generated from a set of 59 CT scans of healthy forearms, encoding the normal anatomical variations. Three different configurations were simulated to predict the pre-traumatic shape with the SSM (cross-validation). In the first two, only the distal or proximal 50% of the radius were considered as pathological. In a third configuration, the entire radius was assumed to be pathological, only the ulna being intact. Corresponding experiments were performed with the ulna. Accuracy of the prediction was assessed by comparing the predicted bone with the healthy model. For the radius, mean rotation accuracy of the prediction between 2.9 ± 2.2° and 4.0 ± 3.1° in pronation/supination, 0.4 ± 0.3° and 0.6 ± 0.5° in flexion/extension, between 0.5 ± 0.3° and 0.5 ± 0.4° in radial-/ulnarduction. Mean translation accuracy along the same axes between 0.8 ± 0.7 and 1.0 ± 0.8 mm, 0.5 ± 0.4 and 0.6 ± 0.4 mm, 0.6 ± 0.4 and 0.6 ± 0.5 mm, respectively. For the ulna, mean rotation accuracy between 2.4 ± 1.9° and 4.7 ± 3.8° in pronation/supination, 0.3 ± 0.3° and 0.8 ± 0.6° in flexion/extension, 0.3 ± 0.2° and 0.7 ± 0.6° in radial-/ulnarduction. Mean translation accuracy between 0.6 ± 0.4 mm and 1.3 ± 0.9 mm, 0.4 ± 0.4 mm and 0.7 ± 0.5 mm, 0.5 ± 0.4 mm and 0.8 ± 0.6 mm, respectively. This technique provided high accuracy, and may replace the current method, if validated in clinical studies. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2630-2636, 2017.

Conventional Versus Computer-Assisted Corrective Osteotomy of the Forearm: a Retrospective Analysis of 56 Consecutive Cases

PURPOSE

Accuracy and feasibility of corrective osteotomies using 3-dimensional planning tools and patient-specific instrumentation has been reported by multiple authors with promising results. However, studies describing clinical outcomes following these procedures are rare. Therefore, the purpose of this study was to compare the results of computer-assisted corrective osteotomies of the diaphyseal and distal radius with a conventional non-computer-assisted technique regarding duration of surgery, consolidation of the osteotomy, and complications. Also, subjective and objective clinical outcome parameters were assessed.

METHODS

We retrospectively compared the results of 31 patients who underwent a corrective osteotomy performed conventionally with 25 patients treated with a computer-assisted method (CA) using patient-specific instrumentation. Baseline data were similar among both groups. The duration of surgery, bony consolidation, complications, gain in range of motion, and subjective outcome were recorded.

RESULTS

The mean operating time was significantly shorter in the CA group compared with the conventional group. After 12 weeks, significantly more osteotomies were considered healed in the CA group compared with the conventional group. Two patients in the CA group required revision surgery to treat nonunion of the osteotomy. Otherwise clinical results were similar among both groups.

CONCLUSIONS

The results demonstrate that the computer-assisted method facilitates shorter operation times while providing similar clinical results.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

A new method of calculating the rotation angle in pediatric forearm fractures using direct radiographs

BACKGROUND

The aim of this study was to measure the rotational angle defect between fracture ends in paediatric forearm diaphyseal fractures on radiographs.

METHODS

Evaluations were performed on 78 paediatric patients who presented at the emergency department with a diaphyseal forearm fracture during 2013-2014. Thirty-two patients who underwent conservative treatment and had < 10° of angulation and translation of not more than half the bone diameter after application of a plaster cast were included in the study. A rotational formula was used with diameter values to determine changes. The degree of rotation of both ends of the fracture line and the forearm rotational defect of the fracture line were calculated.

FINDINGS

Fractures included an isolated radius in 16 cases, an isolated ulna in four cases, and both bones in 12 cases. The mean lateral angular (LAT-θ) value was 26.13 ± 5.93° on the proximal fracture end, and the distal mean LAT-θ was 30.29 ± 6.24° (p = 0.037).The mean proximal anteroposterior angular (AP-θ) value was 26.83 ± 5.75°, and the distal mean AP-θ was 30.58 ± 7.27° (p = 0.008). A significant correlation was detected between the AP-Δ and LAT-Δ measurements (p = 0.883).

INTERPRETATION

The rotational defect was mathematically calculated directly from radiographs using a rotational measurement formula.

[Descriptive, radiographic, topographic and functional anatomy applied to distal radius fractures]

Extensive anatomical knowledge is needed in order to correctly treat distal radius fractures: normal and pathological osteology of the distal radius, distal radio-ulnar joint and radiocarpal joint-both on the descriptive and functional level-the neurovascular and muscular environments of the distal radius-which are essential to the surgical approaches-and the angles that need to be restored during the reduction. All of these concepts are broached in this article.

Anatomic Investigation of Commonly Used Landmarks for Evaluating Rotation During Forearm Fracture Reduction

BACKGROUND

Evaluating rotation during open reduction and internal fixation of a forearm fracture is of paramount importance. In challenging cases, surgeons may utilize radiographic relationships between proximal and distal radial and ulnar landmarks to assess rotational position. However, to our knowledge, limited anatomic data are available to confirm these relationships.

METHODS

Six hundred cadaveric radii and ulnae were obtained. Digital representations of the bicipital tuberosity, the radial styloid, the coronoid process, and the ulnar styloid were acquired, and the rotational profiles between respective landmarks were calculated. In order to validate the results and investigate the ability to differentiate rotated osseous positions, each bone was imaged in increments of 10° of rotation and the profile of each landmark was measured.

RESULTS

The radial styloid was at a mean of 158° ± 14° of supination relative to the bicipital tuberosity. The ulnar styloid was at a mean of 185° ± 14° of supination relative to the coronoid process. Imaging of the bones in increments of 10° of rotation supported the relationships above. It was also found that a 1-mm difference in profile size corresponded to up to 60° of rotation for the average ulna, compared with 10° for the average radius.

CONCLUSIONS

Our findings suggest that using the bicipital tuberosity and the radial styloid to assess intraoperative rotation of the radius on anteroposterior radiographs may be of limited value; the landmarks were not generally 180° apart. Although the rotational positions of the coronoid process and the ulnar styloid were, on average, closer to 180°, surgeons should be aware of the wide range of normal anatomy as well as the inability to judge rotation by as much as 60°, even for an "ideal" ulna.

CLINICAL RELEVANCE

This study, to our knowledge, represents the first anatomic investigation of the rotational profiles between the osseous landmarks used to assess forearm rotation after fracture. We recommend that surgeons first image the bicipital tuberosity at its largest profile, supinate the arm 20°, and confirm that the radial styloid is at its largest profile. The ulna can then be assessed to support the lack of rotational deformity in the forearm.

Measurement of Malrotation on Direct Radiography in Pediatric Distal Radius Fractures: Prospective Observational Study

The aim of this prospective study was to test a mathematical method of measuring the malrotation of pediatric distal radius fractures (PDRFs) from direct radiographs. A total of 70 pediatric patients who presented at the Emergency Department with a distal radius fracture were evaluated. For 38 selected patients conservative treatment for PDRF was planned. Anteroposterior and lateral radiographs were taken of all of the patients for comparison before and after reduction. Radius bone diameters were measured in the coronal and sagittal planes on the healthy and fractured sides. Using the diameter values on the healthy side and the new diameter values on the fractured side in the rotation formula, the degree of malrotation between the fracture ends was calculated. The mean follow-up period was 13.5 months. Patients' mean age was 10.00 ± 3.19 years (range, 4-12 years). The rotation degree in the sagittal plane significantly differed between the proximal (26.52°±2.84°) and distal fracture ends (20.96°±2.73°) (P = 0.001). The rotation degree in the coronal plane significantly differed between the proximal (26.70°±2.38°) and distal fracture ends (20.26°±2.86°) (P = 0.001). The net rotation deformity of the fracture line was determined to be 5.55°± 3.54° on lateral radiographs and 5.44°± 3.35° on anteroposterior radiographs, no significant difference was observed between measurements (P >0.05). The malrotation deformity in PDRF occurs with greater rotation in the proximal fragment than in the distal fragment. The net rotation deformity created between the fracture ends can be calculated on direct radiographs.

LEVEL OF EVIDENCE

Diagnostic, Level II.

Complex forearm deformities: operative strategy in posttraumatic pathology

Complex posttraumatic forearm deformities have a significant impact on the integrity of the upper extremity leading to pain, instability in both the proximal and/or distal radioulnar articulation, and reduced range of forearm motion. Corrective osteotomy or more advanced procedures for malunited fractures or other posttraumatic deformities of the upper extremity, especially in the forearm are challenging procedures. In this review we will discuss the essential aspects of anatomy and pathomechanics, clinical and radiological assessment and the pathway from preoperative planning to the actual deformity correction surgery, either with one-stage correction or using gradual lengthening with external fixation (“callotasis techniques”) and finally the functional outcome we can expect for our patients. In addition we will analyze the modern computer-assisted techniques available to date.

Reconstruction of malunited diaphyseal fractures of the forearm

The forearm is a complex anatomical and functional unit with unique osseous, soft tissue and articular relationships. Disruption of these important relations can have a significant impact, leading to pain, instability of the radio-ulnar articulation and reduced range of motion. The gold standard for treating forearm fractures in adults remains anatomic reduction, stable plate fixation and preservation of the surrounding blood supply. Failure to achieve these goals may lead to malunion, requiring reconstructive surgery, which can be technically challenging. In this review, we discuss the essential aspects of anatomy and pathomechanics, clinical and radiological assessment and the state of the art in pre-operative planning and deformity correction surgery.

Three-dimensional imaging of children with severe limitation of pronation/supination after a both-bone forearm fracture

INTRODUCTION

Although both-bone forearm fractures in children may result in severe limitation of forearm rotation, finding the cause remains a diagnostic challenge. This study tries to evaluate the role of rotational malunion, bony impingement and contractures of the interosseous membrane.

PATIENTS AND METHODS

Children (5-16 years) who suffered from a both-bone forearm fracture in diaphysis or distal metaphysis with a limitation of pronation/supination ≥40° at ≥6 months after trauma were included for analysis with conventional radiographs, computed tomography (CT) and magnetic resonance imaging (MRI).

RESULTS

A total of 410 children with a both-bone forearm fracture were prospectively followed in four Dutch hospitals. At a median of 205 days, 7.3 % suffered from a limitation of pronation/supination ≥40°. 14 children were included (median limitation of 40°) and the radiographs revealed a median maximum angular malunion of 16°. CT analysis showed rotational malunion of both radius (median 19°) and ulna (median 9°). MRI analysis revealed neither bony impingement nor contractures of the interosseous membrane.

CONCLUSIONS

Three-dimensional imaging of children with a severe limitation of pronation/supination after a both-bone forearm fracture revealed rotational malunions of both radius and ulna without bony impingement or soft tissue contractures.

LEVEL OF EVIDENCE

Prospective multicenter study, Level 2.

The bicipital tuberosity and distal radius are unreliable landmarks for radial head implant alignment

BACKGROUND

As more anatomic asymmetric radial head implants emerge, it is necessary to determine the optimal landmarks to ensure correct rotational orientation. The bicipital tuberosity and distal radius are possible bony landmarks that can be used for rotational alignment of asymmetric prostheses; however, they have not been validated. The purpose of this study was to evaluate the reliability of the bicipital tuberosity and distal radius as rotational landmarks for orientation of asymmetric radial head prostheses.

METHODS

Measurements were made from computer tomography scans of 50 elbows in order to determine the rotational relationships between the radial head, bicipital tuberosity, biceps tendon footprint, and distal radius.

RESULTS

The maximum radial head diameter was oriented 65° ± 28° from the bicipital tuberosity, 119° ± 38° from the biceps tendon footprint, 82° ± 29° from the radial styloid, and 76° ± 28° from the volar surface of the distal radius. All of these landmarks had a significantly greater variance than a proposed acceptable clinical tolerance of 10° (P < .001).

CONCLUSION

The results demonstrate that the measured landmarks show no consistent rotational relationship with the maximum diameter of the radial head. In order to maximize the utility of more anatomic asymmetric radial head implant systems, further studies are necessary to identify more reliable rotational landmarks to ensure optimal implant positioning.

3-Dimensional deformity analysis of malunited forearm diaphyseal fractures

PURPOSE

Several biomechanical studies using cadavers have revealed that axial rotation deformity of the forearm bones reduces forearm motion. However, little information is available on the 3-dimensional deformity patterns, including axial rotation deformity in malunited diaphyseal fractures of the forearm. The complex deformity of both forearm bones is difficult to assess on plain radiographs or cross-sectional images. Therefore, we assessed osseous deformity in malunited diaphyseal fractures of the forearm using 3-dimensioinal analysis.

METHODS

We examined 21 patients (16 malunions of both forearm bones and 5 isolated radial malunions). Three-dimensional computer models of bilateral radius and ulna were created from computed tomography data. We evaluated deformity by superimposing the mirror-image bone model of the contralateral normal bone onto a model of the affected bone.

RESULTS

In 21 radial malunions, extension (n = 17) and pronation (n = 16) deformities were common. This tendency was seen particularly in proximal malunions. Average extension, valgus, and pronation deformities were 18°, 2°, and 16°, respectively. In 16 ulnar malunions, valgus (n = 15) and pronation (n = 12) deformities were common. Average flexion, valgus, and pronation deformities were 1°, 11°, and 6°, respectively. Extension deformity of the radius and valgus deformity of the ulna were correlated with restriction of forearm motion.

CONCLUSIONS

Malunited diaphyseal fractures of both forearm bones showed complex deformities, which suggests that 3-dimensional modeling may be a more effective method than standard computed tomography or radiographs. Pronation deformity of the radius may be caused by the supinator and pronator muscles. In addition, the deformity pattern of both bones may indicate that valgus and internal rotation force in the neutral forearm position is applied to both forearm bones after injury.

CLINICAL RELEVANCE

Three-dimensional forearm osteotomy, including rotational realignment, is necessary to obtain anatomical reduction.

Three-dimensional deformity analysis of malunited distal radius fractures and their influence on wrist and forearm motion

Little information exists about three-dimensional (3-D) deformity patterns of malunited distal radius fractures including axial deformity. The current study aimed to clarify the 3-D deformity pattern of malunited distal radius fractures and reveal the influence of osseous deformities, including axial rotation deformity, on wrist and forearm motion. The deformity of 20 dorsally tilted malunions were evaluated using 3-D computer models created from CT data, and correlations between deformity components and range of motion were assessed. The 3-D deformity analysis showed that axial malalignment in pronation, which showed a correlation with the degree of radial tilt deformity, was very common. A radial tilt deformity of > 5° was observed in only 45% of cases. Although the range of wrist flexion and extension showed a correlation with dorsal tilt deformity, the range of forearm pronation and supination did not correlate with distal radius deformities.

Three-dimensional assessment of bilateral symmetry of the radius and ulna for planning corrective surgeries

PURPOSE

The contralateral unaffected side is often used as a reference in planning a corrective osteotomy of a malunited distal radius. Two-dimensional radiographs have proven unreliable in assessing bilateral symmetry, so we assessed 3-dimensional configurations to assess bilateral symmetry.

METHODS

We investigated bilateral symmetry using 3-dimensional imaging techniques. A total of 20 healthy volunteers without previous wrist injury underwent a volumetric computed tomography of both forearms. The left radius and ulna were segmented to create virtual 3-dimensional models of these bones. We selected a distal part and a larger proximal part from these bones and matched them with a mirrored computed tomographic image of the contralateral side. This allowed us to calculate the relative displacements (Δx, Δy, Δz) and rotations (Δφx, Δφy, Δφz) for aligning the left bone with the right bone segments. We investigated the relation between longitudinal length differences in radiuses and ulnas.

RESULTS

Relative differences of the radiuses were (Δx, Δy, Δz): -0.81 ± 1.22 mm, -0.01 ± 0.64 mm, and 2.63 ± 2.03 mm; and (Δφx, Δφy, Δφz): 0.13° ± 1.00°, -0.60° ± 1.35°, and 0.53° ± 5.00°. The same parameters for the ulna were (Δx, Δy, Δz): -0.22 ± 0.82 mm, 0.52 ± 0.99 mm, 2.08 ± 2.33 mm; and (Δφx, Δφy, Δφz): -0.56° ± 0.96°, -0.71° ± 1.51°, and -2.61° ± 5.58°. There is a strong relation between absolute length differences (Δz) between the radiuses and ulnas of individuals.

CONCLUSIONS

We observed substantial length and rotational differences around the longitudinal bone axis in healthy individuals. Surgical planning using the unaffected side as a reference may not be as useful as previously assumed. However, including the length difference of the adjacent forearm bones can be useful in improving length correction in computer-assisted planning of radius or ulna osteotomies and in other reconstructive surgery procedures.

CLINICAL RELEVANCE

Bilateral symmetry is important in reconstructive surgery procedures where the contralateral unaffected side is often used as a reference for planning and evaluation.

Redisplacement of diaphyseal fractures of the forearm after closed reduction in children: a retrospective analysis of risk factors

OBJECTIVES

Manipulation and plaster fixation is the primary management for diaphyseal fractures of the radius and/or ulna in children. This study was designed to evaluate risk factors of fracture redisplacement after closed reduction and cast immobilization.

DESIGN

Retrospective study.

SETTING

Tertiary hospital.

PATIENTS

Fifty-seven children with fractures of the radius were included.

INTERVENTION

The medical records of patients with/without ulna treated with closed reduction and casting were reviewed.

MAIN OUTCOME MEASURES

Data analyzed were age, sex, dominant hand, fracture pattern, reduction quality, experience of the surgeon, and type of anesthesia. Logistic regression was used for multivariate analysis.

RESULTS

There were 41 (71.9%) males and 16 (28.1%) females with a mean age of 9.74 ± 3.07 years. There were 53 radius fractures and 54 ulna fractures, and 22 subjects experienced redisplacement. The redisplacement rate of radius fractures was 34% and of ulnar fractures was 27.8%. Multivariate analysis showed that the factors associated with redisplacement of radius fractures were fair reduction quality [odds ratio (OR), 8.45] and complete fracture (OR 9.62) and those for redisplacement of ulna fractures were fair reduction quality (OR 8.10) and complete fracture (OR 8.43).

CONCLUSIONS

Poorer reduction and complete fracture are more likely to result in redisplacement, and surgical management may be considered in these cases.

Complex radius shaft malunion: osteotomy with computer-assisted planning

We report about two cases with a combined axial and angular malunion of the radius shaft with functional loss of pro-supination. For the preoperative planning, a computer simulation was developed that allows the quantification of the malunion by comparing the 3-d surface model of the impaired bone with the contralateral anatomy. The proximal parts of the left and right radii are superimposed, while the different positions of the distal parts are used to quantify the malunion. This task is performed fully automatically which reduces the overall planning time. The osteotomies were performed according to the results of the computer-aided planning. The first case showed 1 year postoperatively an increase of pronation from 40° to 70° at expense of supination from 95° to 90°. The patient was practically pain-free and reported functional improvement. The second case showed 6 months postoperatively an improvement of supination from 15° to 40° and of pronation from 50° to 60°. The computer-assisted operation planning facilitated the quantification of combined axial and angular malunions which were difficult to detect on plain radiographs.

A morphological approach to the simulation of forearm motion

Computer-based simulations support surgeons in preoperative planning of osteotomy and assessing the improvement of the forearm motion. To this end, an in-silico model of patient-specific forearm kinematics is required. In this paper we introduce a motion model of the forearm which is based on a patient's joint morphology, the form and shape of the joints. The morphology of the articulations is represented by 3-dimensional splines. In this way the gliding motion of the articulations is expressed analytically in a closed-form. Our algorithm was designed to work with available clinical planning data and requires minimal user interaction. This allows an integration in computer-aided planning systems that are operated by surgeons. The accuracy of the simulation results is verified via cadaver experiments.

Intraobserver and interobserver reliability of radial torsion angle measurements by a new and alternative method with computed tomography

OBJECTIVE

To evaluate the intraobserver and interobserver reliability of radial torsion angle measurement using computed tomography.

METHODS

Twelve pairs of cadaver radii and 116 forearms from 58 healthy volunteers were evaluated using axial computed tomography sections measured at the level of the bicipital tuberosity and the subchondral region of the radius. During digital imaging, the angle was formed by two lines, one diametrically perpendicular to the radial tubercle and the other tangential to the volar rim of the distal joint surface. Measurements were performed twice each by three observers.

RESULTS

In cadaveric bones, the mean radial torsion angle was 1.48º (-6º - 9º) on the right and 1.62º (-6 º - 8º) on the left, with a mean difference between the right and left sides of 1.61º (0º - 8º). In volunteers, the mean radial torsion angle was 3.00° (-17° - 17°) on the right and 2.91° (-16°- 15°) on the left, with a mean difference between the sides of 1.58º (0º - 7º). There was no significant difference between each side. The interobserver correlation coefficient for the cadaver radii measurements was 0.88 (0.72 - 0.96) and 0.81 (0.58 - 0.93) for the right and left radius, respectively, while for the volunteers, the difference was 0.84 (0.77 - 0.90) and 0.83 (0.75 - 0.89), respectively. Intraobserver reliability was high.

CONCLUSION

The described method is reproducible and applicable even when the radial tubercle has a rounded contour.

Correction of forearm malunion guided by the preoperative complaint

Diaphyseal malunion of the forearm may cause loss of pronation and supination, a painful distal radioulnar joint, and aesthetic problems. Seventeen patients (10 males, seven females; mean age, 20.6 +/- 9.3 years) were operated on because of symptomatic malunion after a pediatric forearm fracture. Six patients had predominant loss of pronation (Group 1), four had predominant loss of supination (Group 2), and seven had a painful distal radioulnar joint (Group 3). An osteotomy of the radius was performed in seven patients and of both forearm bones in 10. All patients were available for clinical and radiologic assessments at a minimum followup of 6 months (mean +/- standard deviation, 3.7 +/- 2.3 years; range, 0.5-9.9 years). Release of the contracted interosseous membrane frequently was necessary for patients in Groups 1 and 2 to allow for correction and did not result in weakness, instability of the distal radioulnar joint, or synostosis. The overall improvement in range of motion after osteotomies for patients with a supination deficit was much better than in those with a pronation deficit. All patients in Group 3 gained a pain-free and stable distal radioulnar joint and their range of motion was unchanged. Therefore, ability to improve overall range of motion through forearm osteotomies is dependent on the patients' preoperative complaint.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Fluoroscopic and magnetic resonance cross-sectional imaging assessments of radial and ulnar torsion profiles in volunteers

PURPOSE

Planning an osteotomy to correct rotational malunions of the forearm is difficult because the uninvolved side is the only available reference to assess radial and ulnar torsions. This study was designed to compare the reliability of 2 methods for the determination of the torsion profile of both forearm bones and to assess side differences further in volunteers.

METHODS

Fluoroscopy in combination with goniometry and magnetic resonance (MR) cross-sectional imaging were used to determine torsion profiles of the radius and the ulna in 24 asymptomatic volunteers. Interrater and interside reliabilities were assessed.

RESULTS

For the radius, interclass correlation coefficients were less than 0.65 with fluoroscopy and greater than 0.80 with magnetic resonance imaging (MRI). For the ulna, both methods had an interclass correlation coefficient of greater than 0.90. Maximum side-to-side differences assessed with fluoroscopy and MRI were 25 degrees and 34.5 degrees for the radius and 20 degrees and 32 degrees for the ulna, respectively. There were no statistical differences between sides using both methods for both forearm bones.

CONCLUSIONS

Fluoroscopy coupled with goniometry is a valuable method for assessing the torsion profile of the ulna. MR cross-sectional imaging is better to assess the torsion profile of the radius; however, a side difference in torsion profile of up to 35 degrees for the radius and of up to 20 degrees for the ulna should be considered physiologic. Hence, only side differences greater than these limits may serve as an indication for an axial osteotomy in the clinical setting.

Assessment of radial and ulnar torsion profiles with cross-sectional magnetic resonance imaging. A study of volunteers

BACKGROUND

We determined whether the torsion profiles of the radius and ulna could be reliably assessed with cross-sectional magnetic resonance imaging and whether these torsion profiles were comparable on the two sides of volunteers.

METHODS

We assessed magnetic resonance imaging cross sections of the left and right forearms of twenty-four asymptomatic volunteers. The torsion profile of the ulna was defined as the angle formed between a line tangential to the volar cortical surface of the distal part of the humerus and a line connecting the center of the ulnar head and the center of the ulnar styloid. Use of paired proximal and distal landmarks resulted in five different methods of assessment of the radial torsion profile. Intrarater and interrater reliabilities and side-to-side variability were assessed.

RESULTS

This method of assessment of the ulnar torsion profile had intraclass and interclass coefficients of 0.95 and 0.91, respectively. A method previously described by Bindra et al. had the best combined intrarater and interrater reliabilities for assessment of the radius. The mean differences between the right and left sides of the volunteers were the lowest with the use of these two methods; nevertheless, the maximum side-to-side difference was > 30 degrees with techniques.

CONCLUSIONS

Torsion-profile assessment with cross-sectional magnetic resonance imaging had high intrarater and interrater reliabilities. However, individual side-to-side variations in the radial and ulnar profiles are important considerations.

CLINICAL RELEVANCE

Cross-sectional magnetic resonance imaging is currently the only available method to quantify rotational malunion of the radius and ulna. Its low side-to-side reliability warrants comparison between the imaging results and the clinical findings. A side-to-side difference in the rotation profile may serve as a reason to perform an axial osteotomy when the results of the clinical and magnetic resonance imaging assessments are consistent with each other.

[Pro- and supination impairments due to torsional deformities of the radial diaphysis before and after ulna osteotomy]

The aim of this experimental study was to measure the exact influence of torsional deformities at the middle third of the radial shaft before and after osteotomy of the ulnar shaft on the rotation of the forearm. Intact and fresh cadaver specimens were fixed in a newly developed apparatus that allowed free pronation and supination. A ring fixator was applied to the radial shaft with K wires that allowed torsional deformities to be stabilized in steps of 10 degrees. The middle of the radial shaft was osteotomized via a small soft tissue window leaving the other soft tissues including the interosseous membrane intact. Supination and pronation were measured using a goniometer in a standardized fashion. The mean supination value before osteotomy of the radius was 71.6 degrees [standard deviation (SD)15.2 degrees], the mean pronation value was 64.5 degrees (SD 12.4 degrees). Radial osteotomy caused no significant difference in the range of motion prior to creation of torsional deformities. Supination torsional deformities greater than 30 degrees showed a significant loss of pronation and pronation torsional deformities greater than 30 degrees resulted in a significant loss of supination in 14 fresh cadavers, respectively. The amount of mean rotational loss was approximately the same in the respective pronation and supination torsional deformities. In the next step the influence of an ulna osteotomy on the range of motion was evaluated in different torsional deformities. In the four cadavers measured, there was an increase of the range of motion in the direction of the torsional deformity. These values were not significant when compared to values before ulna osteotomy, but there were significant changes to the non deformity (p=0.004 for pronation, p=0.003 for supination). Impairment of range of motion in the opposite direction of the deformity showed a similar appearance as values before ulna osteotomy. Again, there were significant changes to the non deformity (p=0.003 for pronation, p=0.005 for supination).

Anatomical considerations of the radius

Most radial head prostheses do not seem to be based on anatomic data. This may be due partly to the great variation of radial morphology. More importantly, few articles report on the dimensions of the radius. Authors have mainly studied dimensions of the radial head, with less emphasis to the relationship with the rest of the radius. Dimensions of, and relationship between, the proximal and the rest of the radius were measured on 27 fresh-frozen cadaveric upper extremities. Radial head, articulating surface, diaphysis, and distal radius were measured. Angles between the radial neck and diaphysis were defined and calculated. Axes of the distal and proximal radius were defined and radial torsion was calculated. Repeated measures were done by two observers in ten specimens. Inter- and intra-class correlation coefficients were very acceptable. Radial dimensions were found to be highly variable. Calculation of radial torsion showed the largest range. The average torsion was 54 degrees (range = 23-78 degrees). Radial length was 235 mm (range = 207-269 mm). Radial neck length was 13 mm (range = 9-19 mm). We found an average proximal diaphysis-neck angle of 17 degrees (range = 6-28 degrees). End to end-neck angle was 13 degrees (range = 4-22 degrees). Our findings indicate that even with a perfectly anatomical prosthesis, restoration of the anatomical situation can only be achieved when the implant is placed in the correct position. Instrumentation should be developed to allow accurate and reproducible implantation. The measurements we provide may aid this development.

Rotational deformity in malunited fractures of the distal radius

PURPOSE

To evaluate rotational deformity in malunited fractures of the distal radius and its effect on forearm rotation.

METHODS

Thirty-seven patients with a symptomatic malunion of the distal radius (25 with dorsal angulation and 12 with volar angulation) were assessed for rotational deformity of the distal fragment. Spiral computed tomographic scans were taken of both wrists. Rotational deformity was evaluated by comparing the radial torsion angle of the injured and uninjured sides according to Frahm. Multivariable regression analyses were used to identify the radiologic parameter that had the most important influence on forearm rotation.

RESULTS

Of the 37 patients, 23 showed a rotational deformity of the distal radius. In both dorsally and volarly angulated malunions, pronation and supination deformities were identified. There was a tendency toward more pronation deformities with volar malunion. Volar angulated malunion with a rotational deformity of less than 10 degrees showed the smallest amount of forearm supination. Losses of pronation-supination did not correlate with the amount of rotational deformity.

CONCLUSIONS

This study showed that rotational deformity is common with angulated malunions of the distal radius. The effect on forearm rotation should not be overestimated. Pretreatment computed tomographic scanning of both wrists to identify and measure malrotation of the distal radius may be helpful to improve the outcome after corrective osteotomy.

How does torsional deformity of the radial shaft influence the rotation of the forearm? A biomechanical study

OBJECTIVE

The aim of this experimental study was to measure the exact influence of isolated torsional deformities at the middle third of the radial shaft on the rotation of the forearm.

DESIGN

Biomechanical study in cadavers.

SETTING

Trauma Surgery Research Laboratories at the Medical School of Hannover, Hannover, Germany.

INTERVENTION

Fourteen intact and fresh cadaver specimens were fixed in a newly developed apparatus that allowed free pronation and supination. A ring fixator was applied to the radial shaft with K-wires that allowed us to stabilize torsional deformities in steps of 10 degrees. The middle of the radial shaft was osteotomized via a small soft tissue window, leaving the other soft tissues, including the interosseous membrane, intact.

MAIN OUTCOME MEASUREMENT

Supination and pronation were measured using a goniometer in a standardized fashion.

RESULTS

The mean (standard deviation) supination value before osteotomy of the radius was 71.6 degrees (15.2 degrees), and the mean (standard deviation) pronation value was 64.5 degrees (12.4 degrees). Radial osteotomy caused no significant difference in the range of motion before creation of torsional deformities. Supination torsional deformities >30 degrees showed a significant loss of pronation. In turn, pronation torsional deformities >30 degrees resulted in a significant loss of supination. The amount of mean rotational loss was approximately the same in the respective pronation and supination torsional deformities.

CONCLUSION

An axial torsional deformity of the radius of >30 degrees causes a statistically significant loss of forearm rotation in fresh cadavers.

Determining humeral retroversion with computed tomography

BACKGROUND

The purpose of this study was to develop and standardize a technique in which computed tomography images are used to determine the humeral torsion angle with landmarks that can be used during surgery.

METHODS

One hundred and twenty cadaveric humeri were studied. The retroversion of these anatomical specimens was measured on a computed tomography scan and compared with the direct measurements of the specimens. The retroversion of the humerus was measured by determining the orientation of the proximal articular surface of the humerus with respect to the transepicondylar line of the distal part of the humerus and the forearm axis. To evaluate this method of measuring retroversion, the protocol was tested in patients before and after shoulder arthroplasty.

RESULTS

The degree of reproducibility of the measurements made on the computed tomography scan was evaluated by determining the interclass correlation coefficient. The interclass correlation coefficient was considered good (between 0.85 and 0.90) for the measurements of the normal humeri when the orientation of the articular surface measured in the distal part of the humeral head, the epicondylar axis, and the ulnar axis were used as references. There was a significant difference (p < 0.01) between the mean angular orientation of the proximal articular surface with respect to the epicondylar axis (17.6 degrees ) and the mean angular orientation of the proximal articular surface with respect to a line perpendicular to the forearm axis (28.8 degrees ). Despite a wide variation in the humeral torsion angle among the specimens from the different cadavera, the angle varied little between the two normal humeri of the same individual (mean side-to-side difference, 2.1 degrees ).

CONCLUSION

This study demonstrated that retroversion of the proximal part of the humerus can be reliably measured with computed tomography.

CLINICAL RELEVANCE

Determining retroversion with computed tomography is more accurate than palpating the epicondylar axis or using the forearm as a goniometer during surgery. Computed tomography is useful for measuring the amount of rotation of humeri with a malunited fracture or severe arthritic deformity.