Olecranon bone age assessment in puberty using a lateral elbow radiograph and a deep-learning model.

OBJECTIVES: To improve pubertal bone age (BA) evaluation by developing a precise and practical elbow BA classification using the olecranon, and a deep-learning AI model. MATERIALS AND METHODS: Lateral elbow radiographs taken for BA evaluation in children under 18 years were collected from January 2020 to June 2022, retrospectively. A novel classification and the olecranon BA were established based on the morphological changes in the olecranon ossification process during puberty. The olecranon BA was compared with other elbow and hand BA methods, using intraclass correlation coefficients (ICCs), and a deep-learning AI model was developed. RESULTS: A total of 3508 lateral elbow radiographs (mean age 9.8 ± 1.8 years) were collected. The olecranon BA showed the highest applicability (100%) and interobserver agreement (ICC 0.993) among elbow BA methods. It showed excellent reliability with Sauvegrain (0.967 in girls, 0.969 in boys) and Dimeglio (0.978 in girls, 0.978 in boys) elbow BA methods, as well as Korean standard (KS) hand BA in boys (0.917), and good reliability with KS in girls (0.896) and Greulich-Pyle (GP)/Tanner-Whitehouse (TW)3 (0.835 in girls, 0.895 in boys) hand BA methods. The AI model for olecranon BA showed an accuracy of 0.96 and a specificity of 0.98 with EfficientDet-b4. External validation showed an accuracy of 0.86 and a specificity of 0.91. CONCLUSION: The olecranon BA evaluation for puberty, requiring only a lateral elbow radiograph, showed the highest applicability and interobserver agreement, and excellent reliability with other BA evaluation methods, along with a high performance of the AI model. CLINICAL RELEVANCE STATEMENT: This AI model uses a single lateral elbow radiograph to determine bone age for puberty from the olecranon ossification center and can improve pubertal bone age assessment with the highest applicability and excellent reliability compared to previous methods. KEY POINTS: Elbow bone age is valuable for pubertal bone age assessment, but conventional methods have limitations. Olecranon bone age and its AI model showed high performances for pubertal bone age assessment. Olecranon bone age system is practical and accurate while requiring only a single lateral elbow radiograph.

Clinical and radiographic outcome of tension band suture fixation for displaced olecranon fractures.

BACKGROUND: Tension band wire fixation (TBW) is a well-described method for treating displaced olecranon fractures. Further surgery is often needed due to wound breakdown or prominent hardware. An all-suture technique has recently been described as an alternative to TBW but radiographic and clinical outcome are not well established. The aim of this single-center retrospective cohort study was to evaluate outcome after treatment with all-suture technique for simple displaced olecranon fractures. METHODS: A retrospective review of olecranon fractures in patients (> 18 years) treated for displaced olecranon fractures with tension band suture fixation (TBSF) between February and August 2019 was performed in our facility. Primary outcome was revision surgery, which was assessed four years after surgery. Clinical and radiographical follow-up was performed at two weeks, six weeks, three months and six months to assess union rate, fracture displacement, range of motion (ROM), Quick-DASH and Oxford Elbow Score. RESULTS: A total of 24 patients were included. Median age was 64 years [IQR:39-73], 9 patients were male and median ASA score was 2 [IQR:1-2]. 15 fractures were Mayo type 2 A and 9 type 2B with minor comminution. At four-year follow-up, three patients had died. None of the remaining 21 patients had undergone revision surgery. At six months, the median Quick-DASH and Oxford Elbow Score were 2.3 [IQR:0-4.5] and 47 [IQR:46-48], respectively. Median elbow extension and flexion deficits were 0° [IQR:0-2.25] and 0° [IQR:0-0], respectively. Radiographic union was achieved in all patients. In two cases radiographic loss of reduction and malunion was observed but both patients were asymptomatic and had no functional deficits. One patient refractured the elbow due to a second trauma and was reoperated. CONCLUSIONS: TBSF is a promising technique for Mayo type 2 A and 2B fractures with minor comminution. There were no revision surgeries within the first four years. We found good functional outcomes and a high union rate.

Trends and projection of forearm fractures including elbow fractures of the Olecranon in Sweden: an analysis of 363 968 fractures using public aggregated data.

BACKGROUND: Forearm and olecranon fractures are a common orthopaedic injury. This study aimed to analyse whether the incidence of forearm injury is changing and identifying trends in the number of forearm and olecranon fractures using public aggregated data in Sweden. METHODS: The number of forearm and olecranon fractures as defined by the number of registered diagnoses with the ICD-10 code of S52 were collected and normalized per 100,000 inhabitants and stratified per sex, age, and month. Age-adjusted incidence for forearm and olecranon fractures were calculated using the direct method. Poisson regression was used to analyse monthly, seasonal and yearly change in forearm and olecranon fracture incidence. Logistical regression was used to predict future trends of forearm and olecranon fractures. RESULTS: The findings revealed a slight decreasing trend in forearm and olecranon fractures. The average incidence rate during the study period was 333 with women having a higher incidence rate than men. More fractures occurred in the winter months. Fluctuations in the number of forearm and olecranon fractures were observed during 2020 which may be influenced by the COVID-19 pandemic. Based on current data, forearm and olecranon fractures are expected to decrease in Sweden by 2035. CONCLUSION: This study describes the trend of forearm and olecranon fractures among individuals according to sex and age in Sweden using easily obtainable data. Trends in forearm and olecranon fractures are dependent on sex and age but generally show a decreasing trend. More precise studies are needed in order to properly quantify the specific incidence of various subtypes of forearm and olecranon fractures and associated risk factors.

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.

Hydrothermal ablation in recurrent or chronic olecranon bursitis: a prospective study.

BACKGROUND: Olecranon bursitis can be difficult to treat, resulting in persistent or recurrent symptoms. Bursectomy is a frequently applied treatment option for refractory cases but has high complication rates. This is the first in vivo study to investigate the safety and efficacy of hydrothermal ablation, a new treatment modality for recurrent or chronic olecranon bursitis that aims to cause thermal obliteration of the bursal lining by irrigation with heated saline. METHODS: First, a pilot animal trial was set up to determine a safe irrigation temperature window. Second, in a human trial the bursae of patients with chronic, recurrent, or refractory olecranon bursitis were irrigated with a 3-mL/s flow of physiological saline for a duration of 180 seconds at temperatures between 50°C and 52°C. Patients were followed up for 6 months, allowing for assessment of the surgical site to screen for adverse events, volumetric ultrasonographic assessment of the bursae, and collection of the Quick Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH), Patient Global Impression Score, and Clinical Global Impression Score, as well as data on return to activities or work. RESULTS: Twenty-four elbows were prospectively included and underwent a full cycle of hydrothermal ablation. The mean age was 58.4 years (range 40.5-81.5), including 20 male and 4 female patients. None had clinical signs of septic bursitis. Bursal fluid cultures were positive in only 1 case. The average preoperative bursal volume was 11.18 mL (range 4.13-30.75). Eighteen of 24 elbows (75%) were successfully treated, showing a complete remission of symptoms or decided improvement within 6 weeks and without any signs of recurrence during the entire follow-up period of 6 months. The average reduction of ultrasonography-measured bursal volume was 91.9% in the group of patients who responded to treatment. In patients without recurrence, the mean QuickDASH scores before and after treatment were 13.6 (range 0-50) and 3.1 (range 0-27.5), respectively, showing a statistically significant improvement. All patients were able to fully return to work within 6 weeks after the index procedure. No serious adverse events were encountered. Moderate local adverse events were found in 2 patients. Increasing temperatures of irrigation did not result in a higher treatment efficacy. CONCLUSION: Hydrothermal ablation at temperatures between 50°C and 52°C is a safe treatment option for recurrent or chronic olecranon bursitis with fewer complications than open bursectomy and a comparable efficacy.

Orthogonal plating for complex olecranon fractures: retrospective case series with patient-reported outcomes.

INTRODUCTION: Treatment for complex olecranon fractures with metaphyseal comminution can be challenging. To improve reduction maneuvers and augment stability, we apply a small medial and/or lateral locking compression plate (LCP) prior to placing a posterior contoured 3.5 mm-2.7 mm LCP. The aim is to describe our technique and outcomes of this "orthogonal" plating technique. MATERIAL AND METHODS: 26 patients were treated with orthogonal plating. Clinical outcome variables were available for all patients at a median of 27 months (IQR 6-54), and patient-reported outcomes (Q-DASH and MEPS) for 23 patients at 38 months (IQR 18-71). RESULTS: All fractures healed at a median of 2.0 months (IQR 1.5-3.8). The median elbow flexion was 120°, extension-deficit 15°, pronation 88°, and supination 85°. The median Q-DASH was 9 (IQR 0-22) and the median MEPS was 90 (IQR 80-100). Hardware was electively removed in seven patients. One patient had a late superficial infection that resolved with hardware removal and antibiotics, and one patient had two consecutive re-fractures after two hardware removals; and healed after the second revision surgery. CONCLUSION: Orthogonal plating with a posterior LCP and a small medial and/or lateral LCP is a safe technique that leads to excellent healing rates, and good clinical and patient-reported outcomes.

[OLECRANON BURSITIS].

INTRODUCTION: The olecranon bursa is a pocket-like structure located at the posterior aspect of the elbow that is responsible for the smooth movement of the surrounding tissues. Frequently, it is the source of elbow pain due to an inflammation which may be caused by local injury or penetration of bacteria through the skin. This can lead to an initial acute and possibly a late chronic inflammation. Chronic inflammation may originate from systemic diseases such as gout and rheumatoid arthritis as well. The treatment of olecranon bursitis may be conservative (non-surgical) or surgical. Recently, there is more supporting evidence for the use of conservative management over surgical intervention in treating olecranon bursitis.

Influence of bone density on stability in TBW.

Osteoporosis is a common disease that leads to a reduction in bone density and increases the risk of fractures. Stable surgical treatment is particularly important for these fractures. The aim of this study was to examine the influence of bone density in the area of ​​the proximal ulna on the failure of the fixation technique of K-wires in tension band wiring (TBW). We provided 10 ulna specimens with TBW and biomechanically examined the pull-out strength of bi- and tricortical K-wires. Bone density measurement was performed using qCT. In the paired t-test, the tricortical group showed a significantly higher pull-out strength in relation to bone density than the bicortical group (p = 0.001). Furthermore, the Pearson correlation showed a high influence of bone density on pull-out strength in the tricortical group (r = 0.544), but without significance (p = 0.100).Our work shows that bone density has a direct effect on the pull-out strength of K-wires in TBW. TBW should therefore be used as osteosynthesis technique, especially in young patients with non-osteoporotic bones. In the case of osteoporotic fractures, alternative procedures should be preferred.

Percent articular exposure of the distal humerus with triceps fascial tongue approach compared with olecranon osteotomy.

BACKGROUND: Distal humerus fractures are common and can be difficult to treat. No one approach to the distal humerus has been shown to be superior to another; however, the olecranon osteotomy remains the gold standard for complex, intra-articular fractures. Understanding the percent of articular exposure with approaches to the distal humerus is important for success. The goal of this study is to show the percent of articular exposure of the triceps fascial tongue approach as compared with the olecranon osteotomy. METHODS: Twelve fresh frozen cadavers were separated randomly into 2 groups of 6 each. The first group of 6 specimens was allocated to the triceps fascial tongue approaches with the collaterals maintained and with the collaterals released off the ulna and elbow dislocated. The second group of 6 was allocated to the triceps fascial tongue approach while maintaining the collaterals followed by an olecranon osteotomy. The articular exposure was marked after performing each approach, and the percent of articular exposure was quantified by using 3D scanning. Standard deviations were calculated for each. RESULTS: The average percent visualization of the distal humerus articular surface in the fascial tongue approach while maintaining the collaterals was 36% in the first cohort and 37% in the second cohort with a standard deviation of 5% in both cohorts. The average percent of the distal humerus articular surface exposed in the fascial tongue approach with the collaterals released off the ulna and elbow dislocated was 85.09% with a standard deviation of 4%. The average percent of the distal humerus articular surface exposed in the olecranon osteotomy group was 57.9% with a standard deviation of 5%. CONCLUSION: The triceps fascial tongue approach allows for visualization of about one-third of the joint, which may be adequate for many intra-articular distal humerus fractures. For added exposure of the articular surface, the collaterals may be elevated from the ulna and the elbow dislocated allowing for a substantial increase in percent of articular exposure compared with the collateral retaining fascial tongue approach and the olecranon osteotomy.

The medial forearm fascia and lateral forearm fascia contribute to overhead elbow extension in displaced olecranon fractures: a biomechanical study.

BACKGROUND: In nonoperative management of displaced olecranon fractures, patients are able to maintain overhead extension despite a persistent nonunion. It has been hypothesized that this is feasible because of an intact lateral cubital retinaculum. The purpose of this biomechanical study was to determine the contribution of the medial and lateral cubital retinacula to overhead extension in the setting of a displaced olecranon fracture. METHODS: Eight fresh-frozen cadaveric upper-extremity specimens were used in this study. The triceps muscle was loaded through a pulley system operated by an Instron 8874 Biaxial Servohydraulic Fatigue Testing System at a rate of 10 mm/second to simulate overhead elbow extension. Each specimen was tested in 4 states: (1) native state with an intact olecranon; (2) transverse olecranon fracture; (3) transection of 1 cubital retinaculum (medial or lateral); and (4) transection of both medial and lateral cubital retinacula. The primary outcome was the ability to perform overhead extension. The secondary outcome was the force needed to generate extension. RESULTS: Elbow extension was noted in each specimen for trials 1, 2, and 3. Only when both the lateral fascia and medial fascia were transected was elbow extension not achieved. There was no significant difference in the force required to generate extension in the first 3 trials (P = .99). There was no significant difference in the change in the maximum force required to achieve extension between the specimens with only the medial side transected and the specimens with only the lateral side transected (P = .07). DISCUSSION: In the setting of an olecranon fracture, this biomechanical study suggests that if either the lateral or medial cubital retinaculum remains in continuity with the distal ulna, active overhead extension can be maintained. This finding may explain the positive clinical outcomes of nonoperative management of displaced olecranon fractures in the elderly patient population. Determining the integrity of the fascial structures preoperatively may help select candidates for nonoperative treatment of displaced olecranon fractures.

Comparison of clinical outcomes between the olecranon osteotomy approach and the Bryan-Morrey approach for total elbow arthroplasty.

BACKGROUND: This study aims to investigate the clinical efficacy of the olecranon osteotomy approach and the Bryan-Morrey approach in total elbow arthroplasty (TEA). METHODS: In this retrospective study, 49 patients with elbow disease were treated with TEA. A total of 22 patients with TEA by olecranon osteotomy approach were designated as group A, and 27 patients with TEA by Bryan-Morrey approach were designated as group B. There were 22 males and 27 females, aged 32-82 years with a mean age of 62 years. There were 44 cases of unilateral elbow joint, including 27 cases on the left elbow and 17 cases on the right elbow, and 5 cases of the bilateral elbow joint. There were 6 cases of osteoarthritis (7 elbows), 18 cases of rheumatoid arthritis (22 elbows), 14 cases of traumatic arthritis (14 elbows), 7 cases of distal humeral fractures (7 elbows), and 4 cases of elbow tuberculosis (4 elbows). For each group, we recorded the operative time, intraoperative bleeding, elbow flexion, extension, pronation, supination, postoperative complication rates, and Mayo Elbow Performance Score after surgery. RESULTS: Operative time and intraoperative bleeding were less in group A than in group B (53-120 min [70 (62.5, 78) min] vs. 64-105 min [77 (73, 87) min], and 10-200 ml [50 (20, 90) ml] vs. 5-250 ml [100 (50, 150) ml], P < .028). The elbow flexion, pronation activity, and Mayo Elbow Performance Score were higher in group A than in group B, [(121 ± 12)° vs. (112 ± 10)°, 85 (85,85)° vs. 80 (77,85)°, and (94 ± 3) points vs. (91 ± 4) points, P < .036], while elbow extension and supination activity and complication rates were not statistically significant in either group. CONCLUSION: Compared to Bryan-Morrey approach, the olecranon osteotomy approach to TEA provides adequate visualization, saves operative time and reduces bleeding, provides better flexion activity, effectively improves elbow function, and achieves satisfactory clinical outcomes.

Outcomes of Adolescent T-condylar Fractures: Kids Do Not Always Make You Look Good.

BACKGROUND: Optimal treatment for pediatric and adolescent T-condylar fractures remains poorly understood. We sought to assess how functional outcomes and range of motion (ROM) after surgical fixation of T-condylar fractures are affected by patient and surgical factors. METHODS: This is a retrospective cohort study of 52 patients with operatively treated T-condylar fractures at a single tertiary pediatric referral center between 2003 and 2021. All patients younger than 18 at the time of injury with a radiographically confirmed diagnosis were included. RESULTS: Fifty-two T-condylar fractures were included, with a mean patient age of 12.9 years (SD, 2.8). The cohort was 65% male. Nine (19%) fractures were open, 46% (24/52) were AO type C2, and 33% (17/52) occurred in skeletally mature individuals. The surgical approach was through olecranon osteotomy in 29% (15/52) of patients, and fixation included anatomically specific plates and screws in 42% (22/52) of patients. In our cohort, 46% (24/52) achieved good outcomes based on Jarvis ROM criteria and 42% (22/52) achieved good to excellent results based on Roberts functional criteria. The median loss of ROM was 58 degrees at 6 weeks, 20 degrees at 3 and 6 months, and 8 degrees at 1 year postoperatively. We observed a complication rate of 54% (28/52). Patients undergoing adult-type plate fixation had better postoperative range of motion at 6 weeks (ROM loss 52 vs. 80 degrees, P =0.03) and 3 months (10 vs. 35 degrees P =0.004) compared with pediatric-type fixation and trended towards better functional outcomes. We did not identify significant differences in functional outcome scores or complication rates with respect to surgical approach or skeletal maturity. CONCLUSIONS: Surgical fixation of pediatric and adolescent T-condylar fractures achieved a good to excellent functional outcome in only a minority of patients (46% Jarvis / 42% Roberts) with a high rate of postoperative complications (54%). Future work is needed to elucidate optimal treatment to minimize complications and achieve the best functional outcomes in these challenging fractures. LEVEL OF EVIDENCE: Level-IV.

Long-term Functional Consequences of Surgically Treated Pediatric and Adolescent Olecranon Fractures: Does the Presence of Associated Fractures and Surgical Procedure Affect the Results?

BACKGROUND: Olecranon fractures are rare conditions in childhood. The aim of this study was to investigate the factors affecting the results in surgically treated pediatric and adolescent olecranon fractures. METHODS: The orthopaedic trauma database of a large academic tertiary center was retrospectively searched for patients who had sustained an olecranon fracture and were treated surgically between 2005 and 2021. Data related to demographic features, additional fractures, and the presence of any disease were obtained from the patient files. Mayo elbow performance score and the Turkish-language version of the shortened version of the disabilities of arm, shoulder, and hand scale were the main functional outcome measurements. RESULTS: The study included 37 elbows of 34 patients with an average age at the time of surgery of 10.9±3.1 years. The mean follow-up period was 78.2±48.0 months (range, 12 to 196 mo). The 1-year fracture rate of contralateral olecranon was 75% in osteogenesis imperfecta patients. Concomitant fractures were 7 proximal radius, 1 medial epicondyle, and 2 capitellum fractures. The surgical treatment methods were tension band wiring (TBW), open reduction and isolated K-wire fixation, closed reduction and percutaneous fixation (CR-PP), and open reduction-plate fixation. The mean implant removal time in patients treated with closed reduction and percutaneous fixation was 2.2 months, open reduction and isolated K-wire fixation 4.7 months, and TBW 12.7 months ( P =0.004). The mean disabilities of arm, shoulder, and hand scale was 1.9. The mean Mayo elbow performance score was 100. Grade 1 elbow arthritis was determined in 3 patients. No patient underwent revision surgery. CONCLUSIONS: All treatment modalities provided excellent long-term functional results and low complication rates without the need for revision. Closed reduction-percutaneous fixation and open reduction-isolated K-wire fixation were associated with shorter implant removal times compared with TBW. LEVEL OF EVIDENCE: Level III.

Applicability of Shoulder, Olecranon, and Wrist-based Skeletal Maturity Estimation Systems to the Modern Pediatric Population.

BACKGROUND: The proximal humerus ossification system (PHOS), olecranon apophyseal ossification system (OAOS), and modified Fels wrist skeletal maturity system (mFWS) were recently developed or updated using a historical, mostly White, pediatric population. These upper extremity skeletal maturity systems have demonstrated skeletal age estimation performance superior or equivalent to Greulich and Pyle in historical patients. Their applicability to modern pediatric populations has not yet been evaluated. METHODS: We reviewed anteroposterior shoulder, lateral elbow, and anteroposterior hand and wrist x-rays of 4 pediatric cohorts: White males, Black males, White females, and Black females. Peripubertal x-rays were evaluated: males 9 to17 years and females 7 to 15 years. Five nonpathologic radiographs for each age and joint were randomly selected from each group. Skeletal age estimates made by each of the 3 skeletal maturity systems were plotted against the chronological age associated with each radiograph and compared between cohorts, and with the historical patients. RESULTS: Five hundred forty modern radiographs were evaluated (180 shoulders, 180 elbows, and 180 wrists). All radiographic parameters had inter- and intra-rater reliability coefficients at or above 0.79, indicating very good reliability. For PHOS, White males had delayed skeletal age compared with Black males (Δ-0.12 y, P =0.02) and historical males (Δ-0.17 y, P <0.001). Black females were skeletally advanced compared with historical females (Δ0.11 y, P =0.01). For OAOS, White males (Δ-0.31 y, P <0.001) and Black males (Δ-0.24 y, P <0.001) had delayed skeletal age compared with historical males. For mFWS, White males (Δ0.29 y, P =0.024), Black males (Δ0.58 y, P <0.001), and Black females (Δ0.44 y, P <0.001) had advanced skeletal age compared with historical counterparts of the same sex. All other comparisons were not significant ( P >0.05). CONCLUSIONS: The PHOS, OAOS, and mFWS have mild discrepancies in skeletal age estimates when applied to modern pediatric populations depending on the race and sex of the patient. LEVEL OF EVIDENCE: Level III - retrospective chart review.

The Dimeglio Olecranon Method Is Reliable in Diverse, Contemporary Patients for Predicting Future Growth.

BACKGROUND: Growth assessment, which relies on a combination of radiographic and clinical markers, is an integral part of clinical decision-making in pediatric orthopaedics. The aim of this study is to evaluate the accuracy and reliability of the Diméglio skeletal age system using a modern cohort of pediatric patients. METHODS: A retrospective review was undertaken of all patients at a large tertiary pediatric hospital who had lateral forearm radiographs (before the age of 14 y for females and before 16 y for males). In addition, all of these patients had height measurements within 60 days of their forearm x-ray and a final height listed in their medical records. The x-rays were graded by 5 reviewers according to the Diméglio skeletal age system. Inter and intraobserver reliability was tested. RESULTS: One hundred forty-seven patients with complete radiographs and height data were evaluated by 5 observers ranging in experience from medical students to senior pediatric orthopaedic surgeons. The Diméglio system demonstrated excellent reliability across levels of training with an intraobserver correlation coefficient of 0.995 (95% CI, 0.991-0.997) and an interobserver correlation coefficient of 0.906 (95% CI, 0.857-0.943). When the Diméglio stage was paired with age and sex in a multivariable linear regression model predicting the percent of final height, the adjusted R2 was 78.7% (model P value <0.001), suggesting a strong relationship between the Diméglio stage (plus age and sex) and percent of final height. CONCLUSION: This unique approach to maturity assessment demonstrates that the Diméglio staging system can be used effectively in a modern, diverse patient population. LEVEL OF EVIDENCE: Level II; retrospective cohort study.

The Ulnar Olecranon-Coronoid Notch Angle Affects Terminal Elbow Extension in Children and Adolescents.

BACKGROUND: Limitations to terminal elbow extension (TEE) in pediatric populations have been commonly associated with the degree of ligamentous laxity and not bony factors. Ligamentous laxity, quantified through the Beighton score, is criticized for unreliably assessing joint mobility. This study aims to show that the olecranon-coronoid notch angle (OCNA) affects TEE in healthy children and adolescents. METHODS: A retrospective study of 711 pediatric patients treated for upper extremity and shoulder injuries was cross-sectionally studied at 2 tertiary centers from 2014 to 2021. Radiographs were used to measure the OCNA, humerocondylar angle, proximal anterior ulnar angle, and the presence of secondary centers of ossification. A 2-axis goniometer measured clinical TEE to a firm endpoint. The statistical analysis studied the relationships between OCNA and TEE and the effect that age and sex have on these measurements. RESULTS: Increased TEE was associated with increased OCNA (P<0.001) when accounting for age and sex. The average OCNA was 30.0 degrees (7.5 degrees), and the average TEE was 5.6 degrees (8.0 degrees). There was a difference in OCNA between subjects who had elbow hypoextension, normal TEE, and elbow hyperextension (P<0.001). The most common injuries were distal radius fractures (182, 26%), elbow sprains and contusions (111, 16%), distal both bone forearm fractures (95, 14%), single or both bone shaft fractures (77, 11%), and supracondylar fractures (74, 11%). CONCLUSION: These results show that the orientation of the opening of the olecranon-coronoid notch influences the arc of TEE motion in a healthy pediatric population. The notch restrains TEE by activating the bony block mechanism between the olecranon apophysis and the olecranon fossa. The measurement of the OCNA can serve as a reproducible and quantitative method to predict hypomobility to hypermobility of TEE motion. LEVEL OF EVIDENCE: Prognostic study: Level II.

Biomechanical impact of elbow motion in elbow stiffness.

BACKGROUND: A mechanical block in the elbow due to osteophytes in the olecranon fossa is a common clinical symptom for elbow stiffness. PURPOSE/HYPOTHESIS: This study aims to understand the biomechanical characteristics or changes in the stiff elbow in the resting (or neutral) and swing position of the arm using a cadaveric model. The hypotheses included the following: (1) a difference exists in the articular contact pressure of the elbow by comparing the non-stiff and stiff models in in vivo studies; (2) the degree of stiffness would affect the increase of the joint loading of the elbow. STUDY DESIGN: Controlled laboratory study, cadaveric study. METHODS: Eight fresh-frozen specimens from individuals of both sexes were included in the biomechanical study. The specimen was mounted on a custom-designed jig system with gravity-assisted muscle contracture to mimic the elbow in a standing position. The elbow was tested in two conditions (the resting and passive swing). Contact pressure was recorded for three seconds in the resting position, which was the neutral position of the humerus. By dropping the forearm from 90° of the elbow flexion, the passive swing was performed. The specimens were tested sequentially in three stages of stiffness (stage 0, no stiffness; stage 1, 30° of extension limitation; and stage 2, 60° of extension limitation). After data collection was completed in stage 0, a stiff model was sequentially created for each stage. The stiff model of the elbow was created by blocking the olecranon by inserting a 2.0 K-wire into the olecranon fossa horizontally with the intercondylar axis. RESULTS: The mean contact pressures were 279 ± 23, 302 ± 6, and 349 ± 23 kPa in stages 0, 1, and 2, respectively. The increases in the mean contact pressure in stages 2 versus 0 were significant (P < 0.0001). The mean contact pressures were 297 ± 19, 310 ± 14, and 326 ± 13 kPa in stages 0, 1, and 2, respectively. The peak contact pressures were 420 ± 54, 448 ± 84, and 500 ± 67 kPa in stages 0, 1, and 2, respectively. The increases in mean contact pressure in stage 2 versus 0 were significant (P = 0.039). The increases in peak contact pressure in stages 0 versus 2 were significant (P = 0.007). CONCLUSIONS: The elbow bears the load created by gravity and muscle contracture in the resting and swing motion. Moreover, extension limitation of stiff elbow increases the load bearing in the resting position and swing motion. Careful surgical management should be considered for meticulous clearance of bony spur around olecranon fossa to resolve the extension limitation of the elbow.

Three-dimensional cortical and trabecular bone microstructure of the proximal ulna.

INTRODUCTION: The three-dimensional (3D) microstructure of the cortical and trabecular bone of the proximal ulna has not yet been described by means of high-resolution 3D imaging. An improved characterization can provide a better understanding of their relative contribution to resist impact load. The aim of this study is to describe the proximal ulna bone microstructure using micro-computed tomography (micro-CT) and relate it to gross morphology and function. MATERIALS AND METHODS: Five dry cadaveric human ulnae were scanned by micro-CT (17 µm/voxel, isotropic). Both qualitative and quantitative assessments were performed on sagittal image stacks. The cortical thickness of the trochlear notch and the trabecular bone microstructure were measured in the olecranon, bare area and coronoid. RESULTS: Groups of trabecular struts starting in the bare area, spanning towards the anterior and posterior side of the proximal ulna, were observed; within the coronoid, the trabeculae were orthogonal to the joint surface. Consistently among the ulnae, the coronoid showed the highest cortical thickness (1.66 ± 0.59 mm, p = 0.04) and the olecranon the lowest (0.33 ± 0.06 mm, p = 0.04). The bare area exhibited the highest bone volume fraction (BV/TV = 43.7 ± 22.4%), trabecular thickness (Tb.Th = 0.40 ± 0.09 mm) and lowest structure model index (SMI = - 0.28 ± 2.20, indicating plate-like structure), compared to the other regions (p = 0.04). CONCLUSIONS: Our microstructural results suggest that the bare area is the region where most of the loading of the proximal ulna is concentrated, whereas the coronoid, together with its anteromedial facet, is the most important bony stabilizer of the elbow joint. Studying the proximal ulna bone microstructure helps understanding its possible everyday mechanical loading conditions and potential fractures. LEVEL OF EVIDENCE: N.A.

Morphometric feature description of the proximal ulna based on quantitative measurement: a key consideration for implant design.

PURPOSE: To perform quantitative measurements of the anatomic morphology of the proximal ulna and establish the morphologic references based on Chinese for the surgical protocol and implant design. METHODS: The computed tomography data of 156 upper extremities were involved in this study. The ulna model was reconstructed in Mimics. Ten distance and 6 angle parameters were measured by 4 independent investigators with a new quantitative measurement method. The intraclass correlation coefficient was used to evaluate the measuring reliability. Gender and side differences of measured parameters were evaluated. RESULTS: Measurements showed a mean coronoid height of 15 mm, which was 42% of ulnar height with gender-specific differences (mean 16 mm in men and 14 mm in women, P < 0.001). A mean unsupported anteromedial facet width of 8 mm was 61% of the coronoid anteromedial facet. A larger opening angle correlates to a larger olecranon-diaphysis angle (P < 0.001) and larger coronoid height (P = 0.001). A mean proximal ulna dorsal angulation of 4.7° is present in 80% of models at an average of 52 mm distal to olecranon tip. The average proximal ulna varus angulation was 16° at a mean of 74 mm distal to the olecranon tip. Morphological features between the left and right sides were highly consistent. The ICC was between 0.789 and 0.978 for inter-observer and between 0.696 and 0.997 for intra-observer reliability. CONCLUSIONS: The proximal ulna features variable morphology but minor side differences among individuals. Over half of the anteromedial facet was not supported by the proximal ulnar diaphysis, making the coronoid vulnerable to elbow trauma. Preconditioning or customized design of the ulnar plate in the clinical setting with the help of contralateral morphology may be a good choice.

Proximal ulna morphology in various pediatric population age groups: proximal ulna dorsal angulation (PUDA) and olecranon tip-to-apex (TTA) distance.

PURPOSE: To measure proximal ulna dorsal angulation (PUDA) and olecranon tip-to-apex distance (TTA) in pediatric population to aid surgeons with data for proximal ulna fractures fixation. METHODS: Retrospective review of the hospital radiographic database. All elbow radiographs were identified and after implementing exclusion criteria, included were 95 patients aged 0-10; 53 patients aged 11-14; and 53 patients aged 15-18. PUDA was defined as the angle between lines placed on the "flat spot" of the olecranon and the dorsal edge of the ulnar shaft and TTA as the distance between the tip of the olecranon to the apex of angulation. Two evaluators performed measurements independently. RESULTS: In age group 0-10, mean PUDA was 7.53°, range 3.8-13.7, 95% CI 7.16-7.91, while mean TTA was 22.04 mm, range 8.8-50.5, 95% CI 19.92-24.17. In age group 11-14, mean PUDA was 4.99°, range 2.5-9.3, 95% CI (4.61-5.37), while mean TTA was 37.41 mm, range 16.5-66.6, 95% CI (34.91-39.90). In age group 15-18, mean PUDA was 5.18°, range 2.9-8.1, 95% CI (4.75-5.61), while mean TTA was 43.79 mm, range 24.5-79.4, 95% CI (41.38-46.19). PUDA was negatively correlated with age (r = - 0.56, p < 0.001), while TTA was positively correlated with age (r = 0.77, p < 0.001). Reliability levels of 0.81-1 or 0.61-0.80 were achieved for most of intra- and inter-rater reliabilities besides two levels of 0.41-60 and one of 0.21-0.40. CONCLUSION: The main study finding is that in most cases mean age-group values may serve as a template for proximal ulna fixation. There are some cases in which X-ray of contralateral elbow may provide surgeon with a better template. LEVEL OF EVIDENCE: II.