Spatiotemporal characterization of microdamage accumulation and its targeted remodeling mechanisms in diabetic fatigued bone.

The skeleton of type 1 diabetes mellitus (T1DM) has deteriorated mechanical integrity and increased fragility, whereas the mechanisms are not fully understood. Load-induced microdamage naturally occurs in bone matrix and can be removed by initiating endogenous targeted bone remodeling. However, the microdamage accumulation in diabetic skeleton and the corresponding bone remodeling mechanisms remain poorly understood. Herein, streptozotocin-induced T1DM rats and age-matched non-diabetic rats were subjected to daily uniaxial ulnar loading for 1, 4, 7, and 10 days, respectively. The SPECT/CT and basic fuchsin staining revealed significant higher-density spatial accumulation of linear and diffuse microdamage in diabetic ulnae than non-diabetic ulnae. Linear microcracks increased within 10-day loading in diabetic bone, whereas peaked at Day 7 in non-diabetic bone. Moreover, diabetic fatigued ulnae had more severe disruptions of osteocyte canaliculi around linear microcracks. Immunostaining results revealed that diabetes impaired targeted remodeling in fatigued bone at every key stage, including increased apoptosis of bystander osteocytes, decreased RANKL secretion, reduced osteoclast recruitment and bone resorption, and impaired osteoblast-mediated bone formation. This study characterizes microdamage accumulation and abnormal remodeling mechanisms in the diabetic skeleton, which advances our etiologic understanding of diabetic bone deterioration and increased fragility from the aspect of microdamage accumulation and bone remodeling.

Musculoskeletal abnormalities in a large international cohort of boys with 49,XXXXY.

49,XXXXY is the rarest X and Y chromosomal variation, with an incidence of 1 in 80,000-100,000 live male births and has been associated with numerous musculoskeletal abnormalities. Data was collected from an international cohort of boys with 49,XXXXY over 10 years. Children were evaluated by a multidisciplinary team consisting of a pediatric orthopedist, a neurogeneticist, a neurodevelopmentalist, and two physical therapists. Increased rates of torticollis (32.4%), hamstring tightness (42%), radioulnar synostosis (67.6%), pes planus (65.2%), and other foot abnormalities (86.9%) were observed. Several anomalies increased with age, specifically hamstring tightness, kyphosis, and scoliosis. The elucidation of the orthopedic profile of this population is necessary in order to provide healthcare providers with current medical information. This research further supports the necessity for the comprehensive multidisciplinary treatment of boys with 49,XXXXY.

Mid- and Long-Term Outcome After Arthroscopically Assisted Transosseous Triangular Fibrocartilage Complex Refixation-Good to Excellent Results in Spite of Some Loss of Stability of the Distal Radioulnar Joint.

PURPOSE: To evaluate mid- and long-term outcomes after arthroscopically-assisted transosseous reattachment of the triangular fibrocartilage complex (TFCC) and to analyze the association of distal radioulnar joint (DRUJ) stability with the clinical outcome. METHODS: Patients treated with an arthroscopically-assisted transosseous reattachment of the deep layer of the TFCC between 2000 and 2009 and a minimum follow-up of 12 months at mid-term and 4 years at long-term follow-up were retrospectively reviewed. Mayo Modified Wrist Score (MMWS); Disabilities of the Arm, Shoulder and Hand (DASH) score; pain visual analogue scale (VAS); grip strength and stability of the DRUJ were assessed at 2 follow-up clinical examinations. At the last follow-up, the Patient-Rated Wrist Evaluation score was additionally recorded. RESULTS: Thirty patients with a mean age of 29 (±13) years were included. Most of the patients were female (70%, n = 21). The mid-term evaluation took place at a median of 30 months (range, 12-83 months). The assessed scores showed statistically significant clinical improvement (MMWS, P < .001; DASH score P < .001; VAS P < .001). Stability assessment showed a stable DRUJ in 23 (76.7%) patients. At a median of 106 months (range 52-215 months), the long-term clinical assessment was performed. The evaluated scores demonstrated persisting significant improvement (MMWS P < .001; DASH score P < .001; VAS P < .001). Stability assessment showed a stable DRUJ in 19 patients (63.3%). DRUJ instability did not correlate with clinical outcome. No permanent surgery-related complications occurred. CONCLUSION: Arthroscopically-assisted transosseous reattachment of the deep fibers of radioulnar ligaments leads to excellent and good clinical results in mid- and long-term follow-up. In 95.5% of the analyzed patients, the measured improvement in the DASH score exceeded the in literature reported minimal clinically important difference of 13.5. Loss of DRUJ stability during follow-up was not associated with deterioration of clinical parameters and patient satisfaction. LEVEL OF EVIDENCE: Level IV, retrospective case series.

In Vivo Assessment of Cortical Bone Fragility.

PURPOSE OF REVIEW: This review updates readers on recent developments in the assessment of cortical bone fragility in vivo. The review explains the clinical need that motivated the development of Cortical Bone Mechanics Technology™ (CBMT) as a scientific instrument, its unique capabilities, and its necessary further development as a medical device. RECENT FINDINGS: Clinical experience with dual-energy X-ray absorptiometry has led to calls for new clinical methods for assessing bone health. CBMT is a noninvasive, dynamic 3-point bending test that makes direct, functional measurements of the mechanical properties of cortical bone in ulnas of living people. Its technical validity in accurate measurements of ulna flexural rigidity and its clinical validity in accurate estimations of quasistatic ulna bending strength have been demonstrated. Because CBMT is a whole bone test, its measurements reflect the influences of bone quantity and bone quality at all hierarchical levels.

Effect of ulnar angulation and soft tissue sectioning on radial head stability in anterior Monteggia injuries: an in vitro biomechanical study.

BACKGROUND: Radial head instability continues to be a challenge in the management of anterior Monteggia injuries; however, there is a paucity of literature on the factors that contribute to this instability. The aim of this biomechanical investigation was to examine the effects of ulnar angulation and soft tissue insufficiency on radial head stability in anterior Monteggia injuries. METHODS: Six cadaveric arms were mounted in an elbow motion simulator. Radial head translation was measured during simulated active elbow flexion with the forearm supinated. After testing the elbows in the intact state, the ulna was osteotomized and tested at 0°, 10°, 20°, and 30° of extension angulation. To examine the effect of soft tissue insufficiency, the anterior radiocapitellar joint capsule, annular ligament, quadrate ligament, and the proximal and middle interosseous membrane (IOM) were sequentially sectioned. RESULTS: There was a significant increase in anterior radial head translation with greater ulnar extension angulation. Sequential soft tissue sectioning also significantly increased anterior radial head translation. There was no increase in radial head translation with isolated sectioning of the anterior radiocapitellar joint capsule. Additional sectioning of the annular ligament and quadrate ligament slightly increased anterior radial head translation but did not reach statistical significance. Subsequent sectioning of the proximal and middle IOM resulted in significant increases in anterior radial head translation. CONCLUSION: Our study demonstrates that progressive ulnar extension angulation results in an incremental increase in anterior radial head translation in anterior Monteggia injuries. Moreover, increasing magnitudes of soft tissue disruption result in greater anterior radial head instability.

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.

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.

The relationship between maternal and child bone density in Nigerian children with and without nutritional rickets.

We found a positive relationship between bone density in Nigerian children with and without rickets and that of their mothers. After treatment, children with rickets had greater bone density than children without rickets, indicating that children genetically programmed to have greater bone density may have a higher risk of rickets. INTRODUCTION: To determine the relationship between bone density in children with and without rickets and that of their mothers METHODS: Using an unmatched case-control design, forearm areal bone mineral density (aBMD) was measured in 52 and 135 Nigerian children with and without rickets and their mothers, respectively. We performed multivariate linear regression analyses to assess the relationship between maternal and child aBMD Z-scores. RESULTS: Forearm aBMD Z-scores in children were associated with maternal aBMD Z-scores at metaphyseal (effect estimate 0.23; 95% CI 0.08 to 0.37) and diaphyseal (effect estimate 0.16; 0.01 to 0.30) sites, after adjustment for rickets in the child, child's age and sex, height-for-age Z-score, and weight-for-age Z-score. In the adjusted model, rickets was inversely associated with child's aBMD Z-score at the diaphyseal site only (- 0.45, - 0.65 to - 0.24). The positive relationship between maternal and child aBMD Z-scores was marginally greater in children with rickets (slope 0.56, r = 0.47) than without rickets (slope 0.19, r = 0.20) at the diaphyseal site only (P = 0.06 for interaction) but not at the metaphyseal site (slopes 0.35 and 0.30, respectively, P = 0.48). After treatment with calcium for 6 months, metaphyseal aBMD Z-scores were greater in children with treated rickets (effect estimate 0.26; 95% CI 0.02 to 0.49) than in those without rickets. CONCLUSION: In Nigerian children with and without rickets, forearm aBMD Z-scores were positively associated with maternal aBMD Z-scores. Active rickets in the child marginally modified the relationship at the diaphyseal site only. After treatment, children with rickets had greater metaphyseal aBMD Z-scores than children without rickets.

Varus posteromedial rotatory instability: a biomechanical analysis of posterior bundle of the medial ulnar collateral ligament reconstruction.

BACKGROUND: Recently, there has been growing interest in the involvement of the posterior bundle of the medial ulnar collateral ligament (pMUCL) in varus posteromedial rotatory instability (PMRI). Varus PMRI has been observed clinically, but the degree of involvement of the pMUCL remains unclear. This study assessed the degree to which the pMUCL is involved in stabilizing the elbow and the feasibility of a pMUCL reconstruction to restore stability. METHODS: Movements simulating PMRI were performed in 8 cadaveric elbows. Joint gapping values were obtained by 3-dimensional motion capture for the proximal and distal aspects of the ulnohumeral joint. Specimens were assessed at "intact," "cut coronoid + pMUCL," "reconstruction," and "cut anterior aspect MUCL + reconstruction" conditions with mechanical testing at 30°, 60°, and 90° of elbow flexion. RESULTS: Proximal joint gapping significantly increased from intact to cut coronoid + pMUCL at 60° and 90°, and distal joint gapping significantly increased at 90°. In the reconstruction condition, joint gapping across the proximal joint at 60° and 90° significantly recovered, as did distal joint gapping at 90°. In the cut anterior aspect MUCL + reconstruction condition, no significant increase occurred in proximal or distal joint gapping. CONCLUSIONS: Transection of the pMUCL with a coronoid fracture leads to increased joint gapping, suggesting the presence of PMRI. PMRI can still occur with an intact lateral ligamentous complex. A pMUCL tendon graft reconstruction confers some elbow stability in this injury mechanism.

Effect of radiocapitellar Achilles disc arthroplasty on coronoid and capitellar contact pressures after radial head excision.

BACKGROUND: Long-term radiographic arthritis has been commonly reported after radial head excision. Concern over radial head arthroplasty may arise in certain situations including capitellar arthritis, radiocapitellar malalignment, and in young and active patients. We hypothesized that radial head excision increases coronoid contact pressures, which may at least be partially reduced by radiocapitellar Achilles tendon disc arthroplasty. METHODS: Coronoid and capitellar contact pressure was measured on 6 human cadaveric elbows on a custom-designed gravity-valgus simulator under passive flexion from 0° to 90°. Sequential testing, starting with the intact specimen, resection of the radial head, and finally, radiocapitellar Achilles tendon disc arthroplasty were performed on each specimen. RESULTS: Mean contact pressure of the coronoid significantly increased after radial head excision (P < .0001) and significantly improved after Achilles disc arthroplasty (P < .0001). The pressure difference was most pronounced on the lateral coronoid. From 15° to 85° of elbow flexion, mean contact pressures on the lateral coronoid were 291 kPa and 476 kPa before and after radial head excision, respectively (P < .0001). Achilles disc arthroplasty significantly lowered coronoid contact pressures to 385 kPa (P = .002); however, they remained significantly higher than those in the intact radial head group (P = .0009). CONCLUSIONS: Radial head resection increases contact pressure in the coronoid, especially the lateral coronoid. This study showed that radiocapitellar Achilles disc arthroplasty significantly improves contact pressures on the coronoid after radial head resection. Achilles disc arthroplasty could be considered in patients who are not candidates for radial head arthroplasty.

Long-term results after simple rotational osteotomy of the radius shaft for congenital radioulnar synostosis.

BACKGROUND: The present study was conducted to clarify the long-term (≥10 years) results of simple rotational osteotomy for congenital radioulnar synostosis (CRUS). METHODS: Twelve forearms in 9 Asian patients with CRUS who underwent simple rotational osteotomy of the radius shaft were monitored for an average of 13.6 years (range, 10-19 years) postoperatively. Before surgery, the forearm fixation averaged 51.3° of pronation (range, 30°-90°). The true position of the forearm in ankylosis was measured by a line through the styloid processes of the radius and the ulna. Palm pronation and supination angles were also measured. The osteotomy was performed at the insertion of the pronator teres to the shaft of the radius. The pronation position was then corrected manually to allow 90° of palm supination with compensatory rotation around the wrist, and a cast was applied. We evaluated activities of daily living items at a mean of 5.2 years after surgery. At the final follow-up, the 11-item version of the Disability of the Arm, Shoulder and Hand score was recorded. RESULTS: After surgery, the forearm was fixed at an average of 4.2° of supination. At the final follow-up, the palm was able to achieve an average motion arc ranging from 26° of pronation to 62° of supination. There were no neurologic or circulatory complications after surgery. Ability to perform daily activities was markedly improved, and all patients were satisfied with the results of surgery. The average score on the 11-item version of the Disability of the Arm, Shoulder, and Hand was 3.79 points at the final follow-up. CONCLUSION: Our procedure for forearm rotation in patients with CRUS is simple, reliable, satisfactory, and safe.

Functional Outcome of Forearm Rodding in Children With Osteogenesis Imperfecta.

BACKGROUND: The impact of corrective forearm surgery on functional ability in children with osteogenesis imperfecta (OI) has not previously been reported. This study addresses this issue. METHODS: A retrospective chart review was conducted on 19 children with OI who underwent 22 corrective forearm procedures between 1996 and 2013. Functional ability was assessed preoperatively and every year postoperatively using the Pediatric Evaluation of Disability Inventory (PEDI). RESULTS: The mean PEDI self-care score increased by 6.8 (P=0.017) and the mean PEDI mobility score increased by 7.2 (P=0.020) at 1-year postsurgery. Functional gains were greater in moderate OI (types IV, V, and VI) than in severe OI (type III). Improved function was maintained in the majority of cases at a mean of 8.9 years postcorrection. CONCLUSIONS: Corrective forearm surgery in children with OI leads to improved functional ability. LEVEL OF EVIDENCE: Level IV.

Integrative analysis of genome-wide association studies and gene expression profiles identified candidate genes for osteoporosis in Kashin-Beck disease patients.

SUMMARY: The molecular mechanism of osteoporosis (OP) in Kashin-Beck disease (KBD) patients was unclear. Our results suggest that KBD and OP shared some common causal genes, functionally involved in skeletal growth and development and chronic inflammation. Our results provide novel clues for clarifying the molecular mechanism of OP in KBD patients. INTRODUCTION: KBD is a chronic skeletal disorder with osteopenia and OP. The pathogenesis of OP in KBD patients remains elusive. METHODS: A total of 1717 subjects participated in this study. KBD was diagnosed according to the clinical diagnosis criteria of China (GB16395-1996). The bone mineral density (BMD) and bone areas of the ulna and radius, hip, and lumbar (L1-L4) were measured with a Hologic 4500 W dual-energy X-ray absorptiometry scanner. Genotyping was conducted using Affymetrix SNP Array 6.0. Gene expression profiling of peripheral blood mononuclear cells of KBD and OP patients were compared using Affymetrix HG-U133 plus 2.0 arrays and Agilent Human 1A arrays, respectively. Genome-wide association studies (GWAS) were conducted by PLINK. SCEA and DAVID were applied for pleiotropy and functional enrichment analysis, respectively. RESULTS: SCEA analysis observed significant pleiotropic effects between KBD and the ulna and radius BMD (P value = 5.99 × 10(-3)). GWAS meta-analysis identified six candidate genes with pleiotropic effects, including PDGFD, SOX5, DPYD, CTR9, SPP1, and COL4A1. GO analysis identified 16 significant GO shared by KBD and the ulna and radius BMD, involved in cell morphogenesis and apoptosis. Pathway enrichment analysis detected two common pathways for KBD and the ulna and radius BMD, including calcium signaling pathway and vascular smooth muscle contraction pathway. Gene expression analysis detected three up-regulated inflammation-related genes for KBD and OP, including IL1B, IL8, and CCL1. CONCLUSION: This study reported several candidate genes involved in the development of OP in KBD patients.

Bizarre parosteal osteochondromatous proliferation (Nora's lesion) affecting the distal end of the ulna: a case report.

BACKGROUND: Bizarre parosteal osteochondromatous proliferation (BPOP), first described by Nora et al. in 1983 and therefore termed "Nora's lesion", is a rare lesion that occurs in the short bones of the hands and feet and eventually presents as a parosteal mass. Reports of BPOP in the long bones are very rare. A benign disease, BPOP does not become malignant, although a high rate of recurrence following surgical resection is reported. Because of its atypical imaging findings and histopathological appearance, a BPOP might be misdiagnosed as a malignant tumor such as an osteochondroma with malignant transformation, a parosteal osteosarcoma, or a periosteal osteosarcoma. CASE PRESENTATION: A 58-year-old woman complained of left ulnar wrist pain at the time of her initial presentation. Plain x-rays showed ectopic calcifications in and around the distal radioulnar joint, which supported the diagnosis of subacute arthritis with hydroxyapatite crystal deposition. She was initially given a wrist brace and directed to follow-up, but her persistent pain required the administration of corticosteroid injections into the distal radioulnar joint. Increasing ulnar wrist joint pain and limited forearm pronation and wrist flexion necessitated computed tomography and contrast-enhanced magnetic resonance imaging. BPOP was diagnosed based on the preoperative imaging studies, and a resection of the lesion was performed along with the decortication of the underlying the cortical bone to reduce recurrence rates. The diagnosis of BPOP was confirmed by pathologic examination. Two years after surgery, the patient has no subsequent pain complaints and an improved range of motion. CONCLUSIONS: BPOP affecting the distal end of the ulna is exceedingly rare. Because BPOP was diagnosed primarily based upon preoperative imaging findings in our patient, decortication of the underlying cortical bone was performed to reduce recurrence rates. Further careful follow-up in these patients is essential, despite the non-recurrence of the lesion.

Effects on the Distal Radioulnar Joint of Ablation of Triangular Fibrocartilage Complex Tears With Radiofrequency Energy.

PURPOSE: This cadaver study investigated the temperature profile in the wrist joint and distal radioulnar joint (DRUJ) during radiofrequency energy (RFE) application for triangular fibrocartilage complex resection. METHODS: An arthroscopic partial resection of the triangular fibrocartilage complex using monopolar and bipolar RFE was simulated in 14 cadaver limbs. The temperature was recorded simultaneously in the DRUJ and at 6 other anatomic locations of the wrist during RFE application. RESULTS: The mean temperature in the DRUJ was 43.3 ± 8.2°C for the bipolar system in the ablation mode (60 W) and 30.4 ± 3.4°C for the monopolar system in the cut mode (20 W) after 30 seconds. The highest measured temperature in the DRUJ was 54.3°C for the bipolar system and 68.1°C for the monopolar system. CONCLUSIONS: The application of RFE for debridement or resection of the triangular fibrocartilage complex in a clinical setting can induce peak temperatures that might cause damage to the cartilage of the DRUJ. Bipolar systems produce higher mean temperatures than monopolar devices. CLINICAL RELEVANCE: RFE application increases the mean temperature in the DRUJ after 30 seconds to a level that may jeopardize cartilage tissue.

Hemiarthroplasty of the elbow: the effect of implant size on joint congruency.

BACKGROUND: Distal humeral hemiarthroplasty is a treatment option for elbow joint disease that predominantly affects the distal humerus, including distal humerus fractures, nonunions, and avascular necrosis. The effect of hemiarthroplasty implants on joint contact has not been reported. The purpose of this in vitro study was to quantify the effects of hemiarthroplasty and implant size on ulnohumeral joint congruency. METHODS: Five fresh frozen cadaveric upper extremities were mounted to a custom elbow testing system. Active and passive motion were performed in dependent, horizontal, varus, and valgus positions. A registration and interbone distance algorithm was used to quantify ulnohumeral joint congruency throughout elbow flexion. RESULTS: The optimally sized hemiarthroplasty implant demonstrated the greatest joint congruency with the ulna, followed by the oversized implant, then the undersized implant. Joint congruency was greater during active vs. passive flexion, indicating that the elbow joint is more reduced in active flexion than in passive flexion. CONCLUSION: This study demonstrates that undersized distal humeral hemiarthroplasty implants have the lowest joint congruency compared with an optimally sized or oversized implant.

Long-term results after a free vascularized adipofascial graft for congenital proximal radioulnar synostosis with an average follow-up of 10 years: a series of four cases.

BACKGROUND: The aim of this study was to observe the long-term and chronologic changes in clinical and radiologic findings after a free vascularized adipofascial graft interposition with radial osteotomy for congenital proximal radioulnar synostosis (PRUS). METHODS: Six forearms in 4 patients with congenital PRUS who underwent a free vascularized adipofascial graft interposition combined with radial osteotomy were followed up for an average of 10 years (8-12 years) postoperatively. Extension and flexion angles of the elbow and pronation and supination angles of the forearm as well as radiographs were evaluated preoperatively and throughout the postoperative follow-up period. RESULTS: The average extension/flexion angles of the elbow and the average pronation/supination angles of the forearm were 3°/130° and 14°/- before surgery, -4°/135° and 39°/23° at 1 year after surgery, 6°/138° and 44°/30° at 3 years after surgery, and -2°/139° and 35°/7° at the time of the final follow-up, respectively. Final radiographs showed hypertrophy of the radial head in 4 patients, dislocation of the radial head in 2 patients, and deformity of the radial head in 1 patient. CONCLUSIONS: Extension and flexion angles of the elbow in patients with congenital PRUS were constant and the average range of pronation was relatively well maintained throughout the postoperative period, but the average range of supination decreased by 16° from 1 year postoperatively to the time of the final follow-up.

Dynamic decomposition of motion in essential and parkinsonian tremor.

BACKGROUND: Treatment options for essential (ET) and Parkinson disease (PD) tremor are suboptimal, with significant side effects. Botulinum toxin type A (BoNT A) is successfully used in management of various focal movement disorders but is not widely used for tremor. METHOD: This study examines complexity of wrist tremor in terms of involvement of its three anatomical degrees of freedom (DOF) in two common situations of rest and posture. The study examines tremor in 11 ET and 17 PD participants by kinematic decomposition of motion in 3-DOF. RESULTS: Tremor decomposition showed the motion involved more than one DOF (<70% contribution in one DOF) in most ET (rest: 100%, posture: 64%) and PD (rest: 77%, posture: 77%) patients. Task variation resulted in change in both amplitude and composition in ET, but not in PD. Amplitude significantly increased from rest to posture in ET. Directional bias was observed at the wrist for ET (pronation), and PD (extension, ulnar deviation, pronation). Average agreement between clinical visual and kinematic selection of muscles was 55% across all subjects. CONCLUSION: This study shows the complexity of tremor and the difficulty in visual judgment of tremor, which may be key to the success of targeted focal treatments such as BoNT A.

Load transfer at the distal ulna following simulated distal radius fracture malalignment.

PURPOSE: To measure the effects of distal radius malalignment on loading at the distal ulna. METHODS: Using an adjustable mechanism to simulate angulated and translated malalignments, clinically relevant distal radius deformities were simulated in a cadaveric model. A custom-built load cell was inserted just proximal to the native ulna head to measure the resultant force and torque in the distal ulna. Loads were measured before and after transecting the triangular fibrocartilage complex (TFCC). RESULTS: There was an increase in distal ulna load and torque with increasing dorsal translation and angulation. Combined conditions of angulation and translation increased force and torque in the distal ulna to a greater extent than with either condition in isolation. Transecting the TFCC resulted in a reduction in distal ulna load and torque. CONCLUSIONS: A progressive increase in load at the distal ulna was observed with increasing severity of malalignment, which may be an important contributor to residual ulnar wrist pain and dysfunction. However, no clear-cut threshold of malalignment of a dorsally angulated and translated distal radius fracture was identified. These observations suggest that radius deformities cause articular incongruity, which increases TFCC tension and distal radioulnar joint load. Cutting of the TFCC decreased distal ulna loading, likely by releasing the articular constraining effect of the TFCC on the distal radioulnar joint, allowing the radius to rotate more freely with respect to the ulna. CLINICAL RELEVANCE: Anatomical reduction of a distal radius fracture minimizes the forces in the distal ulna and may reduce residual ulnar wrist pain and dysfunction.

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.