Insights into digit evolution from a fate map study of the forearm using Chameleon, a new transgenic chicken line.

The cellular and genetic networks that contribute to the development of the zeugopod (radius and ulna of the forearm, tibia and fibula of the leg) are not well understood, although these bones are susceptible to loss in congenital human syndromes and to the action of teratogens such as thalidomide. Using a new fate-mapping approach with the Chameleon transgenic chicken line, we show that there is a small contribution of SHH-expressing cells to the posterior ulna, posterior carpals and digit 3. We establish that although the majority of the ulna develops in response to paracrine SHH signalling in both the chicken and mouse, there are differences in the contribution of SHH-expressing cells between mouse and chicken as well as between the chicken ulna and fibula. This is evidence that, although zeugopod bones are clearly homologous according to the fossil record, the gene regulatory networks that contribute to their development and evolution are not fixed.

Does the articularis cubiti muscle really exist? Anatomical, histological, and magnetic resonance imaging study with a narrative review of literature.

Although the term articularis cubiti muscle is incorporated in the official anatomical nomenclature, only sparse data about its appearance are available. It is usually described as few fibres originating from the medial head of the triceps brachii muscle and inserting to the capsule of the elbow joint. However, the most recent observations regarding the morphological relations in the posterior elbow region point towards the absence of a well-defined muscle. Therefore, this study was designed to verify the existence of the articularis cubiti muscle in question and to compile more data on the topographical features of the subtricipital area near the posterior aspect of the elbow. To address these questions, 20 embalmed upper limbs were dissected, and seven samples were collected for histological analysis. The laboratory findings were then correlated with 20 magnetic resonance imaging (MRI) scans of the elbow. Consequently, a narrative review of literature was performed to gain more information on the discussed muscle in a historical context. Upon the anatomical dissection, muscular fibres running from the posterior aspect of the shaft of the humerus to the elbow joint capsule and olecranon were identified in 100% of cases. Histologically, the connection with the joint capsule was provided via winding bands of connective tissue. On MRIs, the muscular fibres resembled a well-demarcated thin muscle located underneath the medial head of the triceps brachii muscle. Combined with the review of literature, we concluded that the constant articularis cubiti muscle originates from the posterior shaft of the humerus and attaches indirectly to the posterior aspect of the elbow joint capsule and directly to the superior portion of the olecranon. The obtained results slightly differ from the modern description, but are in agreement with the original publication, which has become misinterpreted throughout time. Presumably, the misused description has led to questioning the existence of an independent muscle. Moreover, our findings attribute to the articularis cubiti muscle, a function in pulling on the posterior aspect of the elbow joint capsule to prevent its entrapment, and possibly also a minor role in extension of the forearm. The presented results should be taken into consideration when intervening with the posterior aspect of the elbow joint because the articularis cubiti muscle poses a consistently appearing landmark.

Effect of different ulnar osteotomies on loading of the distal radioulnar joint: a finite element analysis.

BACKGROUND: Ulnar impingement syndrome is a prevalent source of ulnar carpal pain; however, there is ongoing debate regarding the specific location of shortening, the method of osteotomy, the extent of shortening, and the resulting biomechanical alterations. METHOD: To investigate the biomechanical changes in the distal radioulnar joint (DRUJ) resulting from different osteotomy methods, a cadaveric specimen was dissected, and the presence of a stable DRUJ structure was confirmed. Subsequently, three-dimensional data of the specimen were obtained using a CT scan, and finite element analysis was conducted after additional processing. RESULTS: The DRUJ stress did not change significantly at the metaphyseal osteotomy of 2-3 mm but increased significantly when the osteotomy length reached 5 mm. When the osteotomy was performed at the diaphysis, the DRUJ stress increased with the osteotomy length, and the increase was greater than that of metaphyseal osteotomy. Stress on the DRUJ significantly increases when the position is changed to pronation dorsi-extension. Similarly, the increase in stress in diaphyseal osteotomy was greater than that in metaphyseal osteotomy. When the model was subjected to a longitudinal load of 100 N, neither osteotomy showed a significant change in DRUJ stress at the neutral position. However, the 100 N load significantly increased stress on the DRUJ when the position was changed to pronation dorsi-extension, and the diaphyseal osteotomy significantly increased stress on the DRUJ. CONCLUSIONS: For patients with distal oblique bundle, metaphyseal osteotomy result in a lower increase in intra-articular pressure in the DRUJ compared to diaphyseal osteotomy. However, it is crucial to note that regardless of the specific type of osteotomy employed, it is advisable to avoid a shortening length exceeding 5 mm.

Surgical intervention for distal radial fractures with concurrent ulnar styloid fractures may be beneficial for the elderly patients: a retrospective study.

BACKGROUND: Distal radius fractures are highly prevalent among older adults. Ulnar styloid fractures frequently accompany distal radius fractures, raising concerns about treatment outcomes due to the risk of distal radioulnar joint (DRUJ) instability. This study investigated the necessity of surgical intervention (open reduction internal fixation; ORIF) for distal radius fractures in very old patients with coexisting ulnar styloid fractures. MATERIALS AND METHODS: A retrospective analysis of 96 patients aged ≥ 80 years with AO classification 23-A2 to 23-B3 distal radius fractures with concomitant ulnar styloid fracture between 2019 and 2022 was performed. Patients were excluded if they were aged < 80 years, had a preinjury Barthel index of < 90, or had high-energy multiple trauma. The primary outcome was the Disabilities of the Arm, Shoulder, and Hand (DASH) score assessed at 3, 6, and 12 months. We compared the DASH score and their trajectories between the ORIF and conservative treatment groups. RESULTS: ORIF group demonstrated significantly better DASH functional scores (25.31 ± 4.71) at the 12-month follow-up compared with the conservative group (34.42 ± 8.03; p < 0.001). Treatment choice was identified as a significant predictor of DASH scores at 12 months, with ORIF significantly improved patient's wrist function and demonstrated a ß coefficient of - 9.11 (95% confidence interval: -11.95 to - 6.27, p < 0.001). The other factors investigated, namely age, lowest T-score, and medical history of diabetes mellitus, hypertension, coronary artery disease, cerebrovascular accidents, cancer, and dementia, did not exhibit a significant association with the 12-month DASH scores in the adjusted model (p > 0.05). CONCLUSIONS: Our findings suggest that very old patients with distal radius fracture accompanied by ulnar styloid fractures may benefit from ORIF to achieve optimal long-term functional recovery.

A novel fragment specific classification of complex olecranon fractures: 3-dimensional model design, radiological validation, and proposed surgical algorithm.

BACKGROUND: Current classifications for proximal ulna fracture patterns rely on qualitative data and cannot inform surgical planning. We propose a new classification system based on a biological and anatomical stress analysis. Our hypothesis is that fragment types in complex fractures can be predicted by the tendon and ligament attachments on the proximal ulna. METHODS: First, we completed a literature review to identify quantitative data on proximal ulna soft tissue attachments. On this basis, we created a 3-dimensional model of ulnar anatomy with SliceOMatic and Catia V5R20 software and determined likely locations for fragments and fracture lines. The second part of the study was a retrospective radiological study. A level-1 trauma radiological database was used to identify computed tomography scans of multifragmentary olecranon fractures from 2009 to 2021. These were reviewed and classified according to the "fragment specific" classification and compared to the Mayo and the Schatzker classifications. RESULTS: Twelve articles (134 elbows) met the inclusion criteria and 7 potential fracture fragments were identified. The radiological study included 67 preoperative computed tomography scans (mean 55 years). The fragments identified were the following: posterior (40%), intermediate (42%), tricipital (100%), supinator crest (25%), coronoid (18%), sublime tubercle (12%), and anteromedial facet (18%). Eighteen cases (27%) were classified as Schatzker D (comminutive) and 21 (31%) Mayo 2B (stable comminutive). Inter-rater correlation coefficient was 0.71 among 3 observers. CONCLUSION: This proposed classification system is anatomically based and considers the deforming forces from ligaments and tendons. Having a more comprehensive understanding of complex proximal ulna fractures would lead to more accurate fracture evaluation and surgical planning.

Considerable variation in current coronoid height and fracture measurement techniques: a systematic review.

BACKGROUND: Coronoid fractures usually occur in the presence of a significant osseoligamentous injury to the elbow. Fracture size and location correlate with degree of instability and many authors have attempted to analyze the effect of fracture variation on decision making and outcome. There remains no standardized technique for measuring coronoid height or fracture size. The aim of this study was to appraise the literature regarding techniques for coronoid height measurement in order to understand variation. METHODS: Preferred Reporting Items of Systematic Reviews and Meta-Analyses guidelines were followed. A search was performed to identify studies with either a description of coronoid height, fracture size, or bone loss using the terms (Coronoid) AND (Measurement) OR (Size) OR (Height). Articles were shortlisted by screening for topic relevance based on title, abstract and, if required, full-text review. Exclusion criteria were non-English articles, those on nonhuman species or parts other than the ulna coronoid process, and studies that included patients with pre-existing elbow pathology. Shortlisted articles were grouped based on study type, imaging modality, measurement technique, and measurement parameter as well as its location along the coronoid. RESULTS: Thirty out of the initially identified 494 articles met the inclusion criteria. Twenty-one articles were clinical studies, 8 were cadaveric studies, and 1 combined patients as well as cadavers. A variety of imaging modalities (plain radiographs, 2-dimensional computed tomography [CT], 3-dimensional CT, magnetic resonance imaging or a combination of these) were used with CT scan (either 2-dimensional images or 3-dimensional reconstructions or both) being the most common modality used by 21 studies. Measurement technique also varied from uniplanar linear measurements in 15 studies to multiplanar area and volumetric measurements in 6 studies to techniques describing various angles and indices as an indirect measure of coronoid height in 8 studies. Across the 30 shortlisted studies, 19 different measurement techniques were identified. Fifteen studies measured normal coronoid height while the other 15 measured intact coronoid and/or fracture fragment height. The location of this measurement was also variable between studies with measurements at the apex of the coronoid in 24/30 (80%) of studies. Measurement accuracy was assessed by only 1 study. A total of 12/30 (40%) studies reported on the interobserver and intraobserver reliability of their measurement technique. CONCLUSION: The systemic review demonstrated considerable variability between studies that report coronoid height or fracture size measurements. This variability makes comparison of coronoid height or fracture measurements and recommendations based on these between studies unreliable. There is need for development of a consistent, easy to use, and reproducible technique for coronoid height and bone loss.

A meta-analysis on the diagnostic utility of ultrasound in pediatric distal forearm fractures.

Pediatric distal forearm fractures, comprising 30% of musculoskeletal injuries in children, are conventionally diagnosed using radiography. Ultrasound has emerged as a safer diagnostic tool, eliminating ionizing radiation, enabling bedside examinations with real-time imaging, and proving effective in non-hospital settings. The objective of this study is to evaluate the diagnostic efficacy of ultrasound for detecting distal forearm fractures in the pediatric population. A systematic review and meta-analysis were conducted through a comprehensive literature search in PubMed, Scopus, Web of Science, and Embase databases until October 1, 2023, following established guidelines. Eligible studies, reporting diagnostic accuracy measures of ultrasound in pediatric patients with distal forearm fractures, were included. Relevant data elements were extracted, and data analysis was performed. The analysis included 14 studies with 1377 patients, revealing pooled sensitivity and specificity of 94.5 (95% CI 92.7-95.9) and 93.5 (95% CI 89.6-96.0), respectively. Considering pre-test probabilities of 25%, 50%, and 75% for pediatric distal forearm fractures, positive post-test probabilities were 83%, 44%, and 98%, while negative post-test probabilities were 2%, 6%, and 15%, respectively. The bivariate model indicated significantly higher diagnostic accuracy in the subgroup with trained ultrasound performers vs. untrained performers (p = 0.03). Furthermore, diagnostic accuracy was significantly higher in the subgroup examining radius fractures vs. ulna fractures (p < 0.001), while no significant differences were observed between 4-view and 6-view ultrasound subgroups or between radiologist ultrasound interpreters and non-radiologist interpreters. This study highlighted ultrasound's reliability in detecting pediatric distal forearm fractures, emphasizing the crucial role of expertise in precisely confirming fractures through ultrasound examinations.

Displaced sigmoid notch fracture and higher patient age are associated with distal radioulnar joint subluxation.

Background/aim: Distal radius fractures (DRFs) are frequently associated with distal radioulnar joint (DRUJ) instability. The purpose of this study is to evaluate the effect of the sigmoid notch and ulna styloid fracture types on DRUJ subluxation following closed reduction and casting of DRFs via calculating radioulnar ratio (RUR) on postreduction computed tomography (CT) images. Materials and methods: In our study, postreduction CT images of 202 patients with distal radius fractures were evaluated retrospectively. CT images were evaluated for RUR, sigmoid notch fracture, and ulna styloid types. Sigmoid notch fractures were classified as nondisplaced in the sigmoid notch fractures (NDS) and displaced sigmoid notch (DS) fractures; ulna styloid fractures were grouped as the proximal half ulna styloid (PHUS) and distal half ulna styloid (DHUS) fractures. Results: The mean age of Rozental type 3b (62.8 years) was significantly higher among others. The mean RUR value was significantly higher in Rozental type 3a in compared to type 1a and type 2 fractures. PHUS fractures were more common with DS fractures than DHUS fractures. Conclusion: DS fractures and higher patient age are associated with DRUJ subluxation on postreduction CT images following DRFs. DS fractures are seen more commonly with PHUS fractures than DHUS. Patients with PHUS should be carefully assessed for sigmoid notch fractures and DRUJ congruency. These findings could be helpful for preoperative decision making in the treatment of DRFs.

Reconstruction of oncologic upper extremity defects with fibula free flaps has high union rates and excellent functional outcomes.

BACKGROUND: Limb salvage has better functional outcomes than amputation in the upper extremity. This can however be challenging after bony tumor resections. METHODS: This is a retrospective case series of patients who underwent humerus, ulna, or radius reconstruction with a fibula free flap. Data were collected on demographics, oncologic history, surgical details, and complications. Functional outcome measures included the patient's ability to perform activities of daily living (ADL), presence of pain, and musculoskeletal tumor society (MSTS) score. RESULTS: Over a 25-year period, 38 reconstructions were performed. The flap success rate was 97.5%. Bony union was obtained in 19 of 19 (100%) forearm reconstructions and in 15 of 19 (79%) humerus reconstructions (p = 0.10). All 19 forearm reconstruction patients and 18/19 humerus reconstruction patients were able to perform ADLs with no pain or only occasional pain. The MSTS scores were not significantly different between the humerus and forearm cohorts (27.1 vs. 27.3, p = 0.68). Functional outcomes were significantly better in limbs that achieved union (p < 0.001). Recipient and donor site complications occurred in 10 (26.3%) and 5 (13%) patients, respectively. CONCLUSIONS: Oncologic upper-extremity reconstruction with fibula free flaps has excellent functional outcomes. Bone union is a predictor of superior limb function.

Pediatric parosteal osteosarcoma of the distal radius causing extensive erosive mass effect of the adjacent ulna: a case report.

INTRODUCTION: Parosteal osteosarcomas are low-grade bony malignancies that are treated primarily with surgical resection and reconstruction. This report discusses a unique case of a pediatric patient who presented with a parosteal osteosarcoma of the distal radius causing extensive erosive mass effect and growth disturbance of the adjacent ulna. Likely due to their slow-growing nonaggressive nature, parosteal osteosarcomas have not been previously described to abut adjacent bony structures through direct contact. The patient presented in a significantly delayed manner due to social circumstances, inadvertently revealing this novel behavior. This report reviews this rare case and describes the current understanding of this tumor. CASE PRESENTATION: The patient is a 13-year-old male who presented with a parosteal osteosarcoma of his distal radius. He presented with a palpable wrist mass and wrist stiffness. He presented in a delayed manner with advanced local disease due to social factors. Imaging revealed an osseous radial mass that abutted the ulna and likely stunted its growth. The patient ultimately underwent complex resection and allograft reconstruction of both his distal radius and ulna. Intraoperative pathology was confirmed to have negative tumor margins. Allograft reconstruction of the radius and ulna was performed utilizing patient-specific custom cutting guides. At the 6-month postoperative visit, the patient had no recurrence of the mass, minimal pain, and had almost regained range of motion of the extremities. Clinical radiographs at the 6-month postoperative visit demonstrated allograft incorporation. CONCLUSIONS: A previously unreported case of pediatric parosteal osteosarcoma of the distal radius with erosion of the adjacent ulna through direct contact is presented. The challenges in and the importance of arriving at a definitive diagnosis in a timely manner for the proper treatment of this malignancy are emphasized.

Post-traumatic distal ulnar bifurcation in children: a case report.

BACKGROUND: Galeazzi fracture dislocation is a compound injury that encompasses fractures of the distal third of the radius and dislocation of the distal radial ulnar joint (DRUJ). Clinically, this condition is rare and often leads to distal ulnar bifurcation. In previous similar reports, patients were effectively managed through surgery. CASE PRESENTATION: In this case report, we describe an 11-year-old male child who presented with an ulnar bifida following trauma to the hand, and was treated with manipulation and conservative treatment without surgery. A follow-up performed over the years demonstrated that the patient recovered well, and had normal wrist movements without significant pain, and the patient expressed great satisfaction. CONCLUSIONS: Ulnar diaphyseal fracture may occur in children or adolescents due to injuries, and may be accompanied with manipulation and repositioning. Conservative treatment can be applied to avoid the trauma associated with surgery especially in the absence of severe joint mobility impairment with good outcomes.

Bone-specific median age of hand-wrist maturation from Sudan.

BACKGROUND: Maturation of bones in the hand-wrist region varies among individuals of the same age and among world groups. Although some studies from Africa report differences to other ethnic groups, the lack of detailed bone-specific maturity data prevents meaningful comparisons. AIM: The aim of this study was to describe bone-specific maturity for developing hand-wrist bones in individuals in Khartoum, Sudan. SUBJECTS AND METHODS: The sample was selected from healthy patients attending a dental hospital in Khartoum with known age and ancestry (males = 280, females = 330; aged between 3 and 25 years). Bones were assessed from radiographs of the left hand and wrist after the Greulich and Pyle Atlas (1959). Median ages of attainment for bone stages were calculated using probit analysis for each stage in males and females separately. RESULTS: Maturity data for stages of the phalanges, metacarpals, carpals and radius and ulna in males and females are presented. Median ages in females were earlier compared to males for all stages. These results are largely earlier than previously published findings or where these could be calculated. CONCLUSION: These results of individual maturity stages of phalanges, metacarpals, carpals and the distal epiphyses of the radius and ulna are useful to assess maturity in growing individuals from Sudan.

Does Surgery Improve Healing After Isolated Diaphyseal Ulna Fractures?

PURPOSE: Isolated diaphyseal ulna fractures can be treated nonsurgically or with open reduction and internal fixation (ORIF). It is unclear whether ORIF provides quicker and/or more predictable healing. The purpose of this study was to compare the healing characteristics of isolated diaphyseal ulna fractures after surgical and nonsurgical treatment. METHODS: All patients treated for an isolated diaphyseal (distal- or middle-third) ulna fracture between 2010 and 2018, with a minimum of 3 months of follow-up, were identified. Electronic medical records were reviewed to record patient demographics, assess the treatments used, and compare outcomes. We determined healing and nonunion rates, complications, reoperations, and final radiographic fracture alignment. RESULTS: Ninety-five patients were included with a median follow-up of 20 weeks. Of these, 56 patients were treated nonsurgically and 39 patients were treated with ORIF. At the time of the final follow-up, 51 of the 56 (91.1%) nonsurgically treated fractures had healed and 38 of the 39 (97.4%) surgically managed fractures had healed. There were 5 nonunions after nonsurgical treatment (8.9%) and 1 nonunion after ORIF (2.6%). Eleven patients (19.6%) treated nonsurgically required conversion to ORIF, whereas 4 patients (10.3%) treated with ORIF required reoperation. Middle-third fractures treated nonsurgically had a higher rate of nonunion (30.8%) compared with distal-third fractures treated nonsurgically (2.3%). CONCLUSIONS: The healing characteristics of isolated ulnar shaft fractures do not appear to differ substantially between surgical and nonsurgical treatment. However, nearly 20% of the patients treated nonsurgically may require eventual ORIF. Distal-third fractures may be at a higher risk of conversion to ORIF, and middle-third fractures may be at a higher risk of nonunion. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Long-Term Follow-Up of Ulnar Growth in Radial Dysplasia Treated by a Combination of Distraction and Radialization.

PURPOSE: To study the long-term results of radial club hand, regarding ulna growth, radial angulation, and volar subluxation using a 2-stage treatment protocol. METHODS: From 1998 to 2009, 39 radial club hands (32 patients) were treated with distraction, radialization, and a bilobed flap. Long-term follow-up was available in 13 patients (17 hands; average 12.6 years, range 9-16 years). All 17 hands were classified as Bayne and Klug grade 3 or 4. RESULTS: The average age at distraction was 12 months (SD 5.3). The average age at radialization was 14 months (SD 5.8). At final follow-up, the average ulna length on the involved side was 69.3% of the uninvolved contralateral side in the unilateral cases. In the 4 bilateral cases, the average ulna length was 62% of the ulna length of a cohort of normal children. The transverse diameter of the ulna in the posteroanterior view was 79%, and in the lateral view 99%, of the radius on the contralateral side in the unilateral cases. The average radial deviation improved from 82° to 8° and the average volar subluxation improved from 20° to 12°. However, in 4 hands recurrent volar subluxation and required revision surgery. CONCLUSIONS: This approach to treatment was associated with consistent results in the correction of the radial angulation, volar subluxation, and ulna growth in long-term follow-up. Volar subluxation may result in a requirement for revision. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Demographic heterogeneity in valgus angulation of the proximal ulnar canal in relation to the flexion-extension axis.

BACKGROUND: The long-term outcome of total elbow arthroplasty remains unsatisfactory because of loosening and polyethylene wear, which could be caused by malpositioning of the ulnar component. When introducing an ulnar component, 2 different angles should be considered in the coronal plane: the valgus angulation of the proximal ulna in relation to the flexion-extension axis (FE-axis) and the intramedullary varus angulation in relation to the FE-axis. Currently, available TEA designs may not always be able to reconstruct the FE-axis because of the morphologic variability of the ulna. HYPOTHESIS: This study aimed to determine the demographic variability of the ulna and the relation between the 2 angulations in the frontal plane based on 3-dimentional computed tomography (CT) reconstructions of the elbow joint of healthy volunteers. METHODS: Computed tomography scans of 36 left elbows of healthy volunteers were obtained (20 men and 16 women). The scans were segmented and analyzed using the Mimics Research 20.0 software. A local coordinate system was created based on the FE-axis of the elbow and the ulna's longitudinal axis. The measurements were conducted using the 3-Matic Research 12.0 software. RESULTS: The valgus angulation of the proximal medullary canal was on average 16° in men but 12° in women and ranged between 5° and 21°. The varus angulation of the medullary cavity could be determined at 57 mm in men and 64 mm in women from the FE-axis. This angulation was on average 10° in men and 7° in women. There was no significant correlation between this angle and the length of the ulna or the point of varus angulation. CONCLUSION: This study found a wide range of valgus angulation of the proximal ulnar canal in relation to the FE-axis. The available elbow implant designs are discordant with the mean valgus angulation of the proximal ulna found in this study, and the valgus laxity of the implants does not cover the variability in the population.

Avoiding the posterior interosseous nerve during 2-incision distal biceps tendon repair: an anatomic study.

BACKGROUND: The posterior interosseous nerve (PIN) is the most commonly injured motor nerve during distal biceps tendon repair resulting in severe functional deficits. Anatomic studies of distal biceps tendon repairs have evaluated the proximity of the PIN to the anterior radial shaft in supination, but limited studies have evaluated the location of the PIN in relation to the radial tuberosity (RT), and none have examined its relation to the subcutaneous border of the ulna (SBU) with varying forearm rotation. This study evaluates the location of the PIN in relation to the RT and SBU to help guide surgeons in safe placement of the dorsal incision and the safest zones of dissection. METHODS: The PIN was dissected from arcade of Frohse to 2 cm distal to the RT in 18 cadaver specimens. Four lines were drawn perpendicular to the radial shaft at the proximal, middle, and distal aspect of and 1 cm distal to the RT in the lateral view. Measurements were recorded with a digital caliper along these lines to quantify the distance between the SBU and RT to the PIN with the forearm in neutral, supination, and pronation with the elbow at 90° flexion. Measurements were also made along the length of the radius at the volar, middle, and dorsal surfaces at the distal aspect of the RT to assess its proximity to the PIN. RESULTS: Mean distances to the PIN were greater in pronation than supination and neutral. The PIN crossed the volar surface of the distal aspect of the RT -6.9 ± 4.3 mm (-13, -3.0) in supination, -0.4 ± 5.8 mm (-9.9, 2.5) in neutral, and 8.5 ± 9.9 mm (-2.7, 13) in pronation. One centimeter distal to the RT, mean distance to the PIN was 0.54 ± 4.3 mm (-4.5, 8.8) in supination, 8.5 ± 3.1 mm (3.2, 14) in neutral, and 10 ± 2.7 mm (4.9, 16) in pronation. In pronation, mean distances from the SBU to the PIN at points A, B, C, and D were 41.3 ± 4.2, 38.1 ± 4.4, 34.9 ± 4.2, and 30.8 ± 3.9 mm, respectively. CONCLUSION: PIN location is quite variable, and to avoid iatrogenic injury during 2-incision distal biceps tendon repair, we recommend placement of the dorsal incision no more than 25 mm anterior to the SBU and carrying out deep dissection proximally first to identify the RT before continuing the dissection distally to expose the tendon footprint. The PIN was at risk of injury along the volar surface at the distal aspect of the RT in 50% with neutral rotation and 17% with full pronation.

MDCT evaluation of distal radius fractures and their association with carpal and distal ulnar fractures.

PURPOSE: The purpose of this study was to evaluate the characteristics of distal radius fractures (DRFs) in patients undergoing multi-detector computed tomography (MDCT) and their association with carpal and distal ulnar fractures. METHODS: This retrospective study analyzed 120 patients, who underwent MDCT for evaluation of DRFs. Two radiologists independently evaluated the data for various fracture characteristics and for associated carpal and distal ulnar fractures. RESULTS: Out of 120 DRFs, 74 were complete articular, 40 were partial articular and only 6 were extra-articular. Displacement was present in 99 fractures and intra-articular step off was present in 73 fractures. A total of 81 carpal bone fractures were identified in 46 (38.3%) patients, with more than one carpal bone fracture in 21 patients. Distal ulnar fractures were detected in 79 patients (65.8%), out of which 67 involved the ulnar styloid. DRFs with intra-articular step off were more frequently associated with carpal bone fracture (p value: 0.021), while displaced DRFs were more frequently associated with distal ulnar fracture (p value <0.001). Interobserver agreement for detection of carpal bone fractures (κ = 0.807) and distal ulnar fractures (κ = 0.923) was excellent. CONCLUSION: Majority of DRFs in patients referred for MDCT were complete articular with high incidence of displacement and intra-articular step off. Associated carpal bone and distal ulna fractures were not uncommon.

Distal ulna fractures in adults-subcapitular, transverse fractures did not benefit from surgical treatment.

INTRODUCTION: Fractures of the distal ulna, excluding the styloid, are rare. The cause of injury is often a fall on an outstretched hand with an extended wrist, and in most cases there is a concomitant distal radius fracture. The aims of this retrospective study were to investigate the results of the current treatment of distal ulna fractures in adults, with or without a concomitant distal radius fracture, and if a recently presented fracture classification could predict outcome. MATERIALS AND METHODS: Patients, 18 years or older, treated for a fracture of the distal third of ulna in our county, were included. Fractures of the styloid tip were excluded. The radiographs of the fractures were independently classified by two specialists in radiology according to the 2018 AO/OTA classification. Follow-up was performed 5-7 years after the injury, through the questionnaire Patient-Rated Wrist Evaluation (PRWE) and new radiographs of both wrists. RESULTS: Ninety-six patients with 97 fractures were included and filled out the PRWE. 65 patients also had new radiographs taken. 79 patients were women and the mean age at the time of injury was 63 years (SD 14.5). The most common fracture class was the extra-articular transverse fracture, 2U3A2.3 (42%). We found that 40% of the fractures had been treated by internal fixation and only 2 fractures had not healed, one conservatively treated and one operated. The median PRWE was 15 (IQR 33.5). The PRWE score was significantly worse in the operated ulna fractures (p = 0.01) and this was also true for extra-articular transverse fractures 2U3A2.3 (p = 0.001). Initial displacement was more common in operated transverse fractures, but it could not be proven that this was the reason for the inferior result. CONCLUSIONS: Distal ulna fractures almost always unite and the result is comparable to that of isolated distal radius fractures when measured by PRWE. Based on the opinions of the radiologists and how often a consensus discussion was needed for classification, we found the updated AO classification system difficult to use, if dependent only on standard radiographic views. In the present study, transverse extra-articular ulna fractures did not benefit from internal fixation regardless if associated with a distal radius fracture or isolated.

Outcomes of distal ulna locking plate in management of unstable distal ulna fractures: a prospective case series.

INTRODUCTION: Given the absence of a satisfying plate system to deal with multifragmentary or subcapital distal ulnar fractures, the Distal Ulna Locking Plate (DUL, I.T.S. GmbH, Graz, Austria) could become a useful treatment option. This study aimed to evaluate the results of this anatomically pre-contoured plate regarding patients with unstable or displaced distal ulnar fractures. METHODS: In a prospective clinical trial, 20 patients (18 female, two male; mean age 70 years (24-91 years)) with unstable or displaced distal ulna fractures between December 2010 and August 2015 were analyzed. All patients were treated with open reduction and internal fixation using the DUL. They were evaluated at three follow-up appointments at 3, 6 and 12 months postoperatively regarding their bone healing, ulnar variance (UV), range of motion (ROM) and grip strength. Patient related outcomes were measured using the Disability of the Arm, Shoulder and Hand (DASH), the Patient Rated Wrist Evaluation (PRWE) questionnaires, and the Visual Analogue Scale (VAS). The results after one year were compared to the outcome of the healthy contralateral side. RESULTS: All fractures treated with open reduction and internal fixation using the Distal Ulna Locking Plate healed within 6 months and showed stable ulnar variances after surgery. ROM (rotational plane 81.1 ± 9.0°, sagittal plane 55.1 ± 14.6°, frontal plane 33.0 ± 9.4°) and grip strength (18.7 ± 7.1 N) at the follow-up after 12 month had similar values compared with the uninjured side. The mean DASH score (36.4 ± 29.0), the PRWE-score (14.5 ± 27.0), and the VAS (at rest 0.5 ± 1.1, during activity 1.2 ± 2.4) after one year had no significant difference to the uninjured side. The surgeon's overall satisfaction rate regarding plate handling reached 81.8%. CONCLUSION: Stabilization of unstable distal ulna fractures using the DUL restores nearly normal anatomy and function. Its pre-countered design, volar placement, and enhanced stability present a satisfying plate system. TRIAL REGISTRATION:  The trial was retrospectively Registered at www. CLINICALTRIALS: gov on 16 December 2021 (Trial Registration Number: NCT05329012).

"Mother and baby plate": a strategy to improve stability in proximal fractures of the ulna.

INTRODUCTION: Proximal ulna fractures with a large zone of comminution, such as in the context of Monteggia injuries, require mechanically strong osteosyntheses as they occur in regions with high physiological joint load. Consequently, implant failure and pseudarthrosis are critical and devastating complications, especially with the background of mainly young patients being affected. An effective solution could be provided by adding a small second plate 90° angulated to the standard dorsal plate in the area of non-union. Thus, this study investigates whether, from a biomechanical point of view, the use of such a mini or baby plate is worthwhile. MATERIALS AND METHODS: Comminuted fractures distal to the coronoid process, equivalent to Jupiter type IIb fractures, are generated on artificial Sawbones® of the ulna and stabilized using two different plate osteosyntheses: in the first group, a dorsal locking compression olecranon plate is used (LCP group). In the second group, a small, ulnar 5-hole olecranon plate is added as a baby plate in addition to the mother plate at the level of the fracture zone (MBP group). Dynamic biomechanical loading in degrees of flexion from 0° to 90° is carried out to determine yield load, stiffness, displacement, and changes in fracture gap width as well as bending of the dorsal plate. RESULTS: The "mother-baby-plate" osteosynthesis had a significantly higher yield load (p < 0.01) and stiffness (p = 0.01) than the LCP group. This correlates with the increased movement of the proximal fracture element during cyclic testing for the LCP group compared to the MBP group as measured by an optical metrology system. CONCLUSIONS: Here, we show evidence that the addition of a small plate to the standard plate is highly effective in increasing the biomechanical stability in severe fractures equivalent to Jupiter type IIb. As it hopefully minimizes complications like pseudarthrosis and implant failure and as the additional preparatory effort leading to compromised blood supply is regarded to be negligible, this justifies and highly advises the use of a mother-baby-plate system.