In Vivo Three-Dimensional Analysis of Malunited Forearm Diaphyseal Fractures with Forearm Rotational Restriction

Reproduction of forearm rotation dynamic using intensity-based biplane 2D-3D registration matching method

This study aimed to reproduce and analyse the in vivo dynamic rotational motion of the forearm and to clarify forearm motion involvement and the anatomical function of the interosseous membrane (IOM). The dynamic forearm rotational motion of the radius and ulna was analysed in vivo using a novel image-matching method based on fluoroscopic and computed tomography images for intensity-based biplane two-dimensional-three-dimensional registration. Twenty upper limbs from 10 healthy volunteers were included in this study. The mean range of forearm rotation was 150 ± 26° for dominant hands and 151 ± 18° for non-dominant hands, with no significant difference observed between the two. The radius was most proximal to the maximum pronation relative to the ulna, moved distally toward 60% of the rotation range from maximum pronation, and again proximally toward supination. The mean axial translation of the radius relative to the ulna during forearm rotation was 1.8 ± 0.8 and 1.8 ± 0.9 mm for dominant and non-dominant hands, respectively. The lengths of the IOM components, excluding the central band (CB), changed rotation. The transverse CB length was maximal at approximately 50% of the rotation range from maximum pronation. Summarily, this study describes a detailed method for evaluating in vivo dynamic forearm motion and provides valuable insights into forearm kinematics and IOM function.

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.

Quantitative 3-D CT Demonstrates Distal Row Pronation and Translation and Radiolunate Arthritis in the SNAC Wrist

BACKGROUND

In scaphoid nonunion advanced collapse (SNAC) wrist arthritis, we analyzed the 3-dimensional (3-D) deformity patterns of carpal alignment secondary to scaphoid nonunion and quantified subchondral arthritis by investigating alterations in bone density.

METHODS

We constructed 3-D models of the carpal bones and radius from 51 patients with scaphoid nonunion (nonunion group) and 50 healthy controls (control group). We quantified the differences in 3-D geometric position of the distal carpal row relative to the distal radius in SNAC wrists versus controls. In addition, we assessed the bone density of anatomic regions of interest in the radiocarpal and capitolunate joints relative to the pisiform bone density to characterize degenerative changes in SNAC wrists.

RESULTS

The distal carpal row pronated by a difference of 14° (7.2° versus -6.7°; p < 0.001), deviated ulnarly by a difference of 19° (7.7° versus -11.2°; p < 0.001), shifted dorsally by a difference of 17% of the dorsovolar width of the distal radius (21.0% versus 4.4%; p < 0.001), shifted radially by a difference of 8% of the radioulnar width of the distal radius (13.2% versus 5.3%; p < 0.001), and migrated proximally by a difference of 12% of the lunate height (96.3% versus 108.8%; p < 0.001) in the nonunion group compared with the control group. Additionally, it was found that bone density was greater at the capitolunate joint (capitate head: 140.4% versus 123.7%; p < 0.001; distal lunate: 159.9% versus 146.3%; p < 0.001), the radial styloid (157.0% versus 136.3%; p < 0.001), and the radiolunate joint (proximal lunate: 134.8% versus 122.7%; p < 0.001; lunate fossa: 158.6% versus 148.1%; p = 0.005) in the nonunion group compared with the control group.

CONCLUSIONS

Scaphoid nonunion exhibited a unique deformity pattern and alteration in bone-density distributions. The distal carpal row not only shifted dorsally and migrated proximally but also pronated, deviated ulnarly, and shifted radially. Bone density was greater at the capitolunate joint, the radial styloid, and surprisingly, the radiolunate joint. Our findings give insight into the natural history and progression of arthritis of the SNAC wrist. Additionally, future studies may give insight into whether successful treatment of scaphoid nonunion arrests the progression of arthritis.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Malunion deformity of the forearm: Three-dimensional length variation of interosseous membrane and bone collision

It remains unclear to what extent the interosseous membrane (IOM) is affected through the whole range of motion (ROM) in posttraumatic deformities of the forearm. The purpose of this study is to describe the ligament- and bone-related factors involved in rotational deficit of the forearm. Through three-dimensional (3D) kinematic simulations on one cadaveric forearm, angular deformities of 5° in four directions (flexion, extension, valgus, varus) were produced at two locations of the radius and the ulna (proximal and distal third). The occurrence of bone collision in pronation and the linear length variation of six parts of the IOM through the whole ROM were compared between the 32 types of forearm deformities. Similar patterns could be observed among four groups: 12 types of deformity presented increased bone collision in pronation, 8 presented an improvement of bone collision with an increase of the mean linear lengthening of the IOM in neutral rotation, 6 had an increased linear lengthening of the IOM in supination with nearly unchanged bone collision in pronation and 6 types presented nearly unchanged bone collision in pronation with a shortening of the mean linear length of IOM in supination or neutral rotation. This kinematic analysis provides a better understanding of the ligament- and bone-related factors expected to cause rotational deficit in forearm deformity and may help to refine the surgical indications of patient-specific corrective osteotomy.

Indications and Timing of Guided Growth Techniques for Pediatric Upper Extremity Deformities: A Literature Review

Osseous deformities in children arise due to progressive angular growth or complete physeal arrest. Clinical and radiological alignment measurements help to provide an impression of the deformity, which can be corrected using guided growth techniques. However, little is known about timing and techniques for the upper extremity. Treatment options for deformity correction include monitoring of the deformity, (hemi-)epiphysiodesis, physeal bar resection, and correction osteotomy. Treatment is dependent on the extent and location of the deformity, physeal involvement, presence of a physeal bar, patient age, and predicted length inequality at skeletal maturity. An accurate estimation of the projected limb or bone length inequality is crucial for optimal timing of the intervention. The Paley multiplier method remains the most accurate and simple method for calculating limb growth. While the multiplier method is accurate for calculating growth prior to the growth spurt, measuring peak height velocity (PHV) is superior to chronological age after the onset of the growth spurt. PHV is closely related to skeletal age in children. The Sauvegrain method of skeletal age assessment using elbow radiographs is possibly a simpler and more reliable method than the method by Greulich and Pyle using hand radiographs. PHV-derived multipliers need to be developed for the Sauvegrain method for a more accurate calculation of limb growth during the growth spurt. This paper provides a review of the current literature on the clinical and radiological evaluation of normal upper extremity alignment and aims to provide state-of-the-art directions on deformity evaluation, treatment options, and optimal timing of these options during growth.

Accuracy of 3D Corrective Osteotomy for Pediatric Malunited Both-Bone Forearm Fractures

Re-displacement of a pediatric diaphyseal forearm fracture can lead to a malunion with symptomatic impairment in forearm rotation, which may require a corrective osteotomy. Corrective osteotomy with two-dimensional (2D) radiographic planning for malunited pediatric forearm fractures can be a complex procedure due to multiplanar deformities. Three-dimensional (3D) corrective osteotomy can aid the surgeon in planning and obtaining a more accurate correction and better forearm rotation. This prospective study aimed to assess the accuracy of correction after 3D corrective osteotomy for pediatric forearm malunion and if anatomic correction influences the functional outcome. Our primary outcome measures were the residual maximum deformity angle (MDA) and malrotation after 3D corrective osteotomy. Post-operative MDA > 5° or residual malrotation > 15° were defined as non-anatomic corrections. Our secondary outcome measure was the gain in pro-supination. Between 2016−2018, fifteen patients underwent 3D corrective osteotomies for pediatric malunited diaphyseal both-bone fractures. Three-dimensional corrective osteotomies provided anatomic correction in 10 out of 15 patients. Anatomic corrections resulted in a greater gain in pro-supination than non-anatomic corrections: 70° versus 46° (p = 0.04, ANOVA). Residual malrotation of the radius was associated with inferior gain in pro-supination (p = 0.03, multi-variate linear regression). Three-dimensional corrective osteotomy for pediatric forearm malunion reliably provided an accurate correction, which led to a close-to-normal forearm rotation. Non-anatomic correction, especially residual malrotation of the radius, leads to inferior functional outcomes.

Acute blocking of forearm supination secondary to tearing of the triangular fibrocartilage complex

We studied the characteristics of acute blocking of supination of the distal radioulnar joint caused by triangular fibrocartilage complex injuries. Twenty-four patients who were treated for acute blocking of supination were retrospectively assessed. Supination was suddenly blocked after minor trauma to the wrist. Active and passive supination was severely restricted with a mean preoperative range of motion (11°), whereas pronation was almost normal. The cause was identified arthroscopically or at open operation. It was found to be a result of avulsion of the dorsal or palmar portion of the radioulnar ligament, which blocked movement of the ulnar head. Blocking was reduced manually in four cases, by arthroscopic surgery in eight cases and by open surgery in 12 cases. After treatment, forearm supination improved to 84° of the mean range of motion. Distal radioulnar joint blocking from a ruptured triangular fibrocartilage complex should be considered in the differential diagnosis of loss of forearm supination.Level of evidence: IV.

What Is the Normal Ulnar Bow in Adult Patients?

BACKGROUND

Rotation of the forearm is a result of the complex interaction among the radius, ulna, and interosseous membrane. Although the radius is recognized as curved, the ulna is generally thought of as a "straight bone." To better describe normal anatomy, which may lead to more successful anatomic fixation of forearm fractures, we aimed to apply a method of measuring the normal ulnar bow and determine the mean ulnar bow in adults.

QUESTIONS/PURPOSES

(1) To what degree is the ulna bowed in the coronal and sagittal planes in normal adult forearms? (2) To what degree is the radius bowed in the coronal plane in normal adult forearms?

METHODS

Radiographs of the forearms of adults taken during a 1-year period were initially obtained retrospectively. These radiographs were performed for various reasons, including forearm pain and routine radiographic follow-up. Radiographs were excluded if evidence of a fracture or post-fracture fixation was found, if a patient had missing AP or lateral images, or if a suboptimal technique was used. The coronal and sagittal bow of the ulna was measured with a method adapted from previous studies that assessed radial bow using AP and lateral radiographs, respectively. Similar measurements were made in the coronal plane for the radius. All measurements were performed independently by the four authors. There was excellent interobserver reliability for ulnar bow in the coronal and sagittal planes (interclass correlation coefficient = 0.96 and 0.97, respectively) and for radial bow in the coronal plane (interclass correlation coefficient = 0.90).

RESULTS

The mean maximal coronal ulnar bow was 7 ± 2 mm and was located at 75% of the ulnar length, measured proximally to distally. The location of coronal bow was consistently distal to the radial bow location. The mean maximal sagittal ulnar bow was 6 ± 3 mm and was located at 39% of the ulnar length. The mean maximal coronal bow of the radius was 14 ± 2.0 mm and was 59% of the total length of the radius from proximal to distal.

CONCLUSIONS

The ulna is not a "straight bone," as is commonly thought, but rather has a bow in both the coronal and sagittal planes.

CLINICAL RELEVANCE

Knowledge of the standard ulnar bow may be pivotal to prevent malunion of the ulna during surgery. Future research using these data in preoperative planning may lead to changes in plate contouring and clinical outcomes in forearm fracture management.

Three-Dimensional In Vivo Analysis of Malunited Distal Radius Fractures With Restricted Forearm Rotation

Malunited distal radius fractures (DRFs) occasionally restrict forearm rotation, but the underlying pathology remains unclear. We aimed to elucidate the mechanism of rotational restriction by retrospective analysis of 23 patients with unilateral malunited DRFs who presented restricted forearm rotation. We conducted computed tomography during forearm rotation on both sides. Three-dimensional (3D) bone surface models of the forearm were created, and 3D deformity of the distal radius, translation of the distal radius relative to the ulna, distal radioulnar joint (DRUJ) contact area, and estimated path length (EPL) of distal radioulnar ligaments (DRUL) during forearm rotation were evaluated. In total, 18 patients had dorsal angular deformities (DA group) and five had volar angular deformities (VA group). In the DA group, the closest point between the distal radius and ulna on DRUJ was displaced to the volar side during supination and pronation (p < 0.001); DRUJ contact area was not significantly different between the DA and normal groups. In bone-ligament model simulation, the EPL of dorsal DRUL was longer in the DA group than in the normal group (p < 0.001); opposite phenomena were observed in the VA group. In the DA group, translation of the distal radius in a volar direction relative to the ulna during pronation was impaired presumably due to dorsal DRUL tightness. Anatomical normal reduction of the distal radius by corrective osteotomy may improve forearm rotation by improving triangular fibrocartilage complex tightness and normalizing translation of the distal radius relative to the ulna. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1881-1891, 2019.