Degenerative changes in the elbow joint after radial head excision for fracture: quantitative 3-dimensional analysis of bone density, stress distribution, and bone morphology.

HYPOTHESIS AND BACKGROUND: Some investigators speculate that excision may lead to elbow arthritis and associated problems; however, evidence supporting this theory is limited. It is hypothesized that radial head excision causes bone density changes as a result of asymmetrical stress distributions, consequently leading to osteophyte formation. In this study, we sought to quantitatively compare the 3-dimensional (3D) bone density and stress distributions between operative and nonoperative elbows in patients who underwent radial head excision. Furthermore, we aimed to quantify the bone morphologic changes using 3D models in the same cohort. METHODS: After retrospective identification, this study enrolled 6 patients who had undergone radial head excision for radial head fractures. We created 3D bone models using computed tomography data obtained from the injured and uninjured elbows. Humerus and ulna models were divided into anatomic regions, and the bone density of each region was assessed and described by its percentage of high-density volume (%HDV). We also constructed finite element models and measured the stress values in each region. Furthermore, we compared the bone morphology by superimposing the operative elbow onto the mirror image of the nonoperative elbow. RESULTS: The mean interval from radial head excision to examination was 8.4 ± 3.3 years. The %HDV on the operative side was higher than that of the nonoperative side at the anterolateral trochlea (77.5% ± 6.5% vs. 64.6% ± 4.0%, P = .028) and posterolateral trochlea (70.7% ± 7.8% vs. 63.1% ± 3.8%, P = .034) regions of the distal humerus. Reciprocal changes were observed in the proximal ulna, as %HDV was higher in the lateral coronoid (52.6% ± 9.6% vs. 34.2% ± 6.6%, P = .007). The stress distributions paralleled the bone density measurements. The operative elbows demonstrated an enlarged capitellum and a widened and deepened trochlea with osteophyte formation compared with the nonoperative side. DISCUSSION AND CONCLUSION: In elbows treated with radial head excision, we identified asymmetrical bone density and stress alterations on the lateral side of the ulnohumeral joint and bone morphologic changes across the joint. These data support the theory that radial head excision contributes to ulnohumeral arthritis over the long term.

Injury patterns following simple elbow dislocation: radiological analysis implies existence of a pure valgus dislocation mechanism.

INTRODUCTION: The aim of the present study was to analyze the injury pattern and thus the dislocation mechanism after simple elbow dislocation using radiographs and magnetic resonance imaging (MRI) data sets. MATERIALS AND METHODS: The MRI data sets of 64 patients with a mean age of 44 years (18-77 years) were analyzed retrospectively. The inclusion criteria for the study were (1) radiograph with confirmed simple elbow dislocation, (2) low-energy trauma, (3) MRI of the affected elbow ≤ 3 weeks after trauma. The dislocation direction was determined using radiographs. The integrity of the lateral collateral ligament complex (LCLC), common extensor origin (CEO), anterior capsule (AC), medial collateral ligament (MCL), and common flexor origin (CFO) as well as the joint congruity were assessed based on MRI. RESULTS: 34 patients (53%) had a posterolateral, 26 patients (41%) a posterior, and 4 patients (6%) a posteromedial dislocation. LCLC and AC were affected in 64 out of 64 patients (100%). MCL was affected in 58 patients (91%). CEO were affected in 25 patients (39%) and the CFO in 20 patients (31%). In 11 patients (17%) the injury pattern was more pronounced medially than laterally (MCL, CFO, LCLC), with 2 of these patients exhibiting only a partial LCLC tear. All cases with joint incongruency (n = 12, 19%) showed CEO and/or CFO involvement. CONCLUSIONS: Simple elbow dislocation leads to a very heterogeneous spectrum of soft tissue injury pattern. A small proportion of patients showed medially pronounced injury patterns. These findings strongly indicate existence of a "reversed Horii circle" with an underlying valgus mechanism (medial force induction) originating and continuing from medial to anterior.

Cartilage thickness of distal humerus and its relationships with bone dimensions: magnetic resonance imaging bilateral study in healthy elbows.

BACKGROUND: Little is known about the cartilage thickness of the distal humerus and how it affects the shape of the articular surface. Our aims were to assess cartilage thickness and to determine the extent to which it affects the true profile of the distal humerus. METHODS: We assessed 78 healthy elbows (39 subjects, 19 women and 20 men) with a mean age of 28 years (range, 21-32 years). Cartilage thickness was measured by use of high-definition magnetic resonance imaging scans at 19 different points of the articular surface, 13 on the trochlea and 6 on the capitellum, on the axial and coronal views. Bone diameters at the medial and lateral trochlear ridges, trochlear groove, and capitellum, as well as the articular surface width, were measured. Subject height was used as an indirect measurement of humerus length. Pearson correlation coefficients and the Student t test were used. RESULTS: Cartilage thickness showed a significant variation (range, 0.4-1.8 mm) independent of sex and side. It appeared thinner at the medial and lateral edges, whereas it increased at the level of the trochleocapitellar and trochlear grooves, the lateral trochlear ridges, and the center of the capitellum. The mean bone diameters of the medial ridge, lateral ridge, trochlear groove, and capitellum measured 25.1 mm, 21 mm, 16.9 mm, and 19.6 mm, respectively. The mean width of the articular surface was 42.9 mm (range, 35.8-50.2 mm). No significant correlation was found between cartilage thickness and bone dimensions. CONCLUSION: Cartilage thickness is not uniform and modifies the morphologic shape and diameters of the humeral articular surface. These findings may be relevant to anatomic prosthesis design.

Identification of overlengthening after replacement of the radial head with a bipolar prosthesis.

INTRODUCTION: Overlengthening of the radial column leads to insufficient functionality and increased capitellar wear. Methods to detect or prevent overlengthening have been described for monopolar prostheses. The aim of this study was to evaluate whether one such method described by Athwal et al. is also applicable for a bipolar prosthesis. MATERIALS AND METHODS: The radial heads of six fresh frozen upper extremities were resected. A bipolar radial head prosthesis was implanted in each, and the effects of sequential overlengthening on the alignment of the radiocapitellar and ulnohumeral joint line were recorded by fluoroscopic images. Digital image analysis and estimation of overlengthening followed according to the method described by Athwal et al. RESULTS: Statistical analysis of the estimated and actual differences between the native state and bipolar replacement of the radial head with stepwise overlengthening of 1.5, 3, 4.5, and 6 mm showed a specificity of 86 % but consistently underestimated the amount of overlengthening with a sensitivity of only 61 %. DISCUSSION: The method described by Athwal et al. for the identification of overlengthening by a monopolar prosthesis was not found to be reliable for ruling out or quantifying overlengthening of the tested bipolar prosthesis. However, the use of the method to detect (rule in) overlengthening may be acceptable in certain circumstances. A reliable method for postoperative quantification of overlengthening by bipolar prostheses has still to be found.

Acute Simple Elbow Dislocations in the United States: An Epidemiological Analysis of Trends Including COVID-19.

Background Elbows are one of the most frequently dislocated large joints; however, there is limited epidemiological data, especially during the coronavirus disease 2019 (COVID-19) pandemic. This study characterizes elbow dislocations presenting to Emergency Departments (EDs) over the last decade. Methods This study is a cross-sectional, descriptive, epidemiologic analysis of isolated elbow dislocations presenting to EDs from 2011-2020 using the National Electronic Injury Surveillance System (NEISS) database. Patients under 10, those with radial head subluxation, and those with complex fractures were excluded. Data on incidence ratios, patient demographics, mechanisms of injury, and incident locales were analyzed. Results Approximately 83,996 simple, primary elbow dislocations occurred from 2011-2020 (n=2,328), generating an incidence of 2.98/100,000 person-years. Incidence was higher among males (3.26 versus 2.69/100,000 person-years). Dislocations peaked in patients aged 10-19, with higher rates in males (11.12 versus 5.31/100,000 person-years; injury rate ratio 2.09, CI=2.05-2.14, p<0.001). Rates of elbow dislocations decreased with age in males (age 20-29=11.12, age >80=0.63/100,000) but increased in females over 40 (age 40-49=1.59, age 70-79=2.83/100,000). Athletic activities accounted for 55% of dislocations (n=45,902), with 15% from football and 14% from wrestling. The fewest annual dislocations occurred during COVID-19 (n=6440). Injuries occurring at schools and during contact and indoor sports decreased, while those from soccer increased. Conclusions Elbow dislocations are common, with trends of decreasing incidence with age among men and increasing incidence in women over 40. COVID-19 impacted sports-related and epidemiologic injury patterns. Ultimately, understanding population-level risks for elbow dislocations enables orthopaedic surgeons to predict injury trends and conceive educational preventative measures.

Intraoperative arthroscopic classification tool for posterolateral elbow instability.

Background: Introducing and implementing an arthroscopic classification tool for posterolateral elbow instability. Methods: Thirty arthroscopies were performed on 30 patients, and all recordings were collected, blinded, and labeled. Three orthopedic surgeons reviewed and scored all 30 recordings three times with a period of at least seven days in between to analyze the intraobserver and interobserver reliability. The classification consisted of five different grades. Results: Indications for elbow arthroscopy included impingement (n = 7), osteochondritis dissecans (n = 5), pain (n = 7), osteoarthritis (n = 6), and other (n = 5). The kappa value for intrarater reliability was 0.71, indicating good reliability, while the kappa value for inter-rater reliability was 0.38 indicating fair reliability. Conclusion: This new classification is a tool for an arthroscopic assessment of PLRI and can be used as a standardized grading system for further research and communication between orthopedic surgeons. We demonstrated good intrarater reliability (k = 0.71) with fair inter-rater reliability (k = 0.38). However, further research is necessary to study the clinical significance.

Triple suture fixation for displaced comminuted olecranon fracture with a stable ulnohumeral joint.

PURPOSE: To report the outcome of a novel fixation technique using three high-strength sutures which is including articular buttress suture, cerclage suture, and tension band with off-loading triceps suture (triple suture fixation) in the treatment of displaced comminuted olecranon fracture with a stable ulnohumeral joint (Mayo type IIB). The rationale of using this technique is that the sutures have been used to stabilize multiple fracture fragments in all sides of the olecranon. MATERIAL AND METHODS: Between July 2018 and July 2021, 10 patients (7 women, 3 men; mean age, 49.9 years; mean follow-up duration, 27.8 months) with Mayo type IIB olecranon fractures who underwent triple suture fixation were included in the study. The elbow was immobilized in a splint for 2 weeks postoperatively. Range-of-motion exercises were initiated after splint removal and weight bearing was allowed at 6 weeks postoperatively. RESULTS: Average active range of motion of the elbow was 145° of flexion (range, 135°-150°), 6.5° of extension (range, 0°-30°), 83° of supination (range, 70°-85°), and 77.5° of pronation (range, 70°-80°). Mean MEPS was 98.3 (range, 85-100) and DASH score was 3.1 (range, 0-10) at the final follow-up. Radiographic data at the final follow-up analyzed by paired t test demonstrated that there was no statistically significant difference of proximal olecranon height (OH), trochlear notch width (TW), and OH/TW ratio between postoperative treatment and normal side (p-value >.05). No complication of implant prominence, fixation failure, nonunion, infection or heterotopic ossification was found postoperatively. Breakage of drill bit occurred during drilling a distal oblique hole for articular buttress suture in one patient. CONCLUSION: The triple suture fixation is an effective treatment with low incidence of complications in treatment of Mayo type IIB olecranon fractures. Larger comparative studies are needed to confirm the value of such technique.

The sonographic posterolateral rotatory stress test: Normal ulnohumeral gap difference in healthy volunteers.

Background: The sonographic posterolateral rotatory stress test may be a good preoperative diagnostic tool for posterolateral rotatory instability, especially in atraumatic or occult cases. However, there is lack of study on the living population or the normal elbow. Hypothesis/Purpose: This study evaluates the ulnohumeral opening gap difference between elbows in resting and stress positions while performing ultrasonography in normal healthy volunteers. The hypothesis is that the normal ulnohumeral opening gap difference is less than 2 mm. Methods: A total of 21 participants (9 males and 12 females) who presented at our institution between May and June 2021 were recruited. First, participants with elbow deformity, major elbow trauma, history of injection or surgery around the elbow, or evidence of elbow instability were excluded. Only healthy elbows without symptoms were included in this study. Participants' both elbows were examined using ultrasonography. The ulnohumeral gap was measured in millimeters, and the difference was calculated from the means of ulnohumeral gap in resting and stress positions. Results: The mean age of participants was 36.14 years old. No samples with hyperlaxity were included. Overall, the means of ulnohumeral gap in resting and stress positions were 2.55 ± 0.69 mm and 3.16 ± 0.80 mm, respectively. The average mean of overall ulnohumeral opening gap difference was 0.61 ± 0.32 mm. There was no statistically significant difference between males and females (p = .989). The intraobserver reliability was 0.89 and 0.9 for resting and stress positions, respectively. Conclusion: The sonographic posterolateral rotatory stress test shows that the ulnohumeral opening gap difference between resting and stress positions is less than 2 mm in healthy volunteers. Clinical Relevance: In patients with inconclusively-diagnosed PLRI, the sonographic posterolateral rotatory stress test may be a reliable preoperative diagnosis tool, providing its non-invasiveness and the ability to assess the contralateral side as a comparison.

A missed medial humeral epicondyle fracture with incarcerated fragment in the elbow joint and ulnar nerve palsy: A rare case report.

Medial epicondyle fracture associated with incarcerated intra-articular fragment and ulnar nerve palsy is uncommon and frequently missed. We report a case of 13-year-old boy with incarcerated medial epicondyle fracture fragment in ulnohumeral joint and ulnar nerve palsy, which was managed successfully by open reduction internal fixation and ulnar nerve transposition.

A New Pediatric Monteggia Fracture Type 4 Variant.

Introduction: Monteggia fracture-dislocations are rare and complex injuries that usually involve a fracture of the proximal ulna associated with a proximal radioulnar and radiocapitellar joint dislocations. These injuries comprise <1% of all pediatric forearm fractures. We report on a pediatric Monteggia fracture-dislocation variant that included an irreducible divergent ulnohumeral joint dislocation, an irreducible anterior radial head dislocation, and a proximal and distal radius and ulna fracture. Case Report: A 6-year-old female came to our emergency room with a right elbow and forearm pain and deformity after a fall from a slide on the same day. X-rays revealed a divergent ulnohumeral joint dislocation, an anterior radiocapitellar joint dislocation, a proximal radioulnar joint dislocation, and a proximal and distal ulna and radius fracture. Closed reduction under sedation in the emergency room was not successful, with persistent ulnohumeral, ulnoradial, and radiocapitellar joint dislocations. The patient was taken to the operating room the next morning. She underwent open reduction and internal fixation of the proximal ulna fracture with a one-third tubular locking plate, and radial head dislocation open reduction. A stable reduction of the ulnohumeral joint was only possible after the fixation of the proximal ulna fracture. The most stable position for the radiocapitellar joint after its open reduction was at 70o of elbow extension and full forearm supination; the patient was casted in that position for 6 weeks. Conclusion: Pediatric Monteggia fracture-dislocations are rare and complex childhood fractures, and new variants of this injury can have even more complex presentations. Open reduction and stable internal fixation addressing all components of this injury will lead to an excellent outcome.