Radial Head Subluxation After Malalignment of the Proximal Ulna: A Biomechanical Study

Irreducible isolated anteromedial radial head dislocation due to ruptured anterior capsule and annular ligament interposition: A case report

Traumatic radial head dislocation without a bone-associated lesion is uncommon, and irreducible cases are rare. We herein present a case of isolated irreducible anteromedial radial head dislocation due to anterior capsule and annular ligament interposition in a 16-year-old female patient. The patient was injured when she was thrown by an opponent during a judo match, and her right elbow was outstretched, combined with forearm pronation. Open reduction was required because of soft tissue interposition into the radiocapitellar joint. The ruptured anterior capsule and annular ligament were repaired using the overlapping suture technique; hence, the radial head was stabilized. At 3.5 years follow-up, the patient had satisfactory elbow function, and redislocation did not occur; however, mild degenerative changes were observed on radiographs. We discussed the injury mechanism using anatomical features in this case and previous literature.

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.

Finite Element Analysis of Elbow Joint Stability by Different Flexion Angles of the Annular Ligament

Objective

The injury of the annular ligament can change the stress distribution and affect the stability of the elbow joint, but its biomechanical mechanism is unclear. The present study investigated the biomechanical effects of different flexion angles of the annular ligament on elbow joint stability.

Methods

A cartilage and ligament model was constructed using SolidWorks software according to the magnetic resonance imaging results to simulate the annular ligament during normal, loosened, and ruptured conditions at different buckling angles (0°, 30°, 60°, 90°, and 120°). The fixed muscle strengths were 40 N (F1), 20 N (F2), 20 N (F3), 20 N (F4), and 20 N (F5) for the triceps, biceps, and brachial tendons and the base of the medial collateral ligament and lateral collateral ligament. The different elbow three‐dimensional (3D) finite element models were imported into ABAQUS software to calculate and analyze the load, contact area, contact stress, and stress of the medial collateral ligament of the olecranon cartilage.

Results

The results showed that the stress value of olecranon cartilage increased under different conditions (normal, loosened, and ruptured annular ligament) with elbow extension, and the maximum stress value of olecranon cartilage was 2.91 ± 0.24 MPa when the annular ligament was ruptured. The maximum contact area of olecranon cartilage was 254  mm² with normal annular ligament when the elbow joint was flexed to 30°, while the maximum contact area of loosened and ruptured annular ligament was 283 and 312 mm² at 60° of elbow flexion, and then decreased gradually. The maximum stress of the medial collateral ligament was 6.52 ± 0.23, 11.51 ± 0.78, and 18.74 ± 0.94 MPa under the different conditions, respectively.

Conclusion

When the annular ligament ruptures, it should be reconstructed as much as possible to avoid the elevation of stress on the surface of the medial collateral ligament of the elbow and the annular cartilage, which may cause clinical symptoms.

The pediatric proximal ulna: a radiographic study

INTRODUCTION

The proximal ulna has been comprehensively described in the anatomic literature and imaging studies. However, to the best of our knowledge, the anatomy of the proximal ulna in children has not been fully described in the literature.

METHODS

The present study was conducted on 189 children aged between 0 and 12 years (4.7 ± 2.7) by analysis of lateral X-rays of the forearm. Proximal ulna dorsal angulation (PUDA), tip-to-apex (TTA), and total ulnar length (TUL) were measured. The correlation between age and the various X-ray measurements was recorded and then compared with gender differences and adult measurements. Three orthopedic surgeons independently examined the X-ray films and confirmed the reliability of the original observations through intra-group correlation coefficients.

RESULTS

There was a strong positive correlation between age and TUL (r = 0.834), and a moderately negative correlation between age and PUDA (r = - 0.405). No significant differences were observed between different genders (p > 0.05). Compared with adults, all measurements were smaller except for PUDA, all such measurements statistically significantly different between children and adults (p < 0.05). Interobserver and intraobserver reliability were "very good" for TUL (0.81-1.00), and "good" for PUDA, TTA, and TTA% (0.61-0.80).

CONCLUSIONS

Good understanding of the anatomy of the pediatric proximal ulna will help to increase the knowledge base in pediatric orthopedic surgeons allowing them to provide improved treatment of fractures. Restoration of the correct forearm anatomy should result in superior clinical and functional results.

The role of biceps loading and muscle activation on radial head stability in anterior Monteggia injuries: An in vitro biomechanical study

INTRODUCTION

Little evidence-based information is available to direct the optimal rehabilitation of patients with anterior Monteggia injuries.

PURPOSE OF THE STUDY

The aims of this biomechanical investigation were to (1) quantify the effect of biceps loading and (2) to compare the effect of simulated active and passive elbow flexion on radial head stability in anterior Monteggia injuries.

STUDY DESIGN

In vitro biomechanical study.

METHODS

Six cadaveric arms were mounted in an elbow motion simulator. The effect of biceps loading, simulated active and passive elbow flexion motions was examined with application of 0N, 20N, 40N, 60N, 80N, and 100N of load. Simulated active and passive elbow flexion motions were then performed with the forearm supinated. Radial head translation relative to the capitellum was measured using an optical tracking system. After testing the intact elbows, the proximal ulna was osteotomized and realigned using a custom jig to simulate an anatomical reduction. We then sequentially sectioned the anterior radiocapitellar joint capsule, annular ligament, quadrate ligament, and the proximal and middle interosseous membrane to simulate soft tissue injuries commonly associated with anterior Monteggia fractures.

RESULTS

Greater magnitudes of biceps loading significantly increased anterior radial head translation. However, there was no significant difference in radial head translation between simulated active and passive elbow flexion except in the final stage of soft tissue sectioning. There was a significant increase in anterior radial head translation with progressive injury states with both isometric biceps loading and simulated active and passive motion.

CONCLUSIONS

Our results demonstrate that anatomic reduction of the ulna may not be sufficient to restore radial head alignment in anterior Monteggia injuries with a greater magnitude of soft tissue injury. In cases with significant soft tissue injury, the elbow should be immobilized in a flexed and supinated position to allow relaxation of the biceps and avoid movement of the elbow in the early postoperative period.

Proximal ulna fractures in adults: A review of diagnosis and management

Proximal ulna fractures are relatively common upper limb injuries, which may represent fragility fractures or result from high-energy trauma. These include fractures of the olecranon, coronoid and associated radial head dislocations. A wide variety of treatment options are available for the management of these injuries that makes the selection of most appropriate treatment difficult. We aim to provide a brief overview of the treatment options for such injuries.

Evaluation of the association between olecranon fracture and radial head subluxation or annular ligament displacement in children

Olecranon fractures are seen substantially more often in children than in adult and are potentially occult in nature. We noticed this fracture pattern in two cases of delayed Monteggia fracture. Our study purpose was to confirm whether olecranon fracture is associated with radial head subluxation or annular ligamentous displacement in children. In addition, we have developed an effective and simple approach to avoid serious treatment-related complications as much as possible. Forty-eight pediatric patients with olecranon fracture and normal radiocapitellar alignment on radiography were enrolled. All patients' fingers, forearms and elbows were examined carefully, and treated with a modified radial head reduction approach and then cast immobilization. MRI of the affected elbow was performed in 16 symptomatic patients. Overall, 70.83% of patients had a positive clinical finding of radial head subluxation. These symptomatic patients presented with similar clinical findings that typically included painful finger movement actively or passively and movement limitation of forearm and elbow. MRI showed that annular ligaments were interposed and trapped in the radiohumeral joint. In 34 symptomatic patients, 91.18% of them achieved fair radial head reduction during the first reduction attempt. Herein, 95.85 and 100% of patients reported excellent and satisfactory outcomes, respectively. Radial head subluxation occurred in most children with an olecranon fracture. We highly suggest performing a careful physical examination to identify this fracture pattern. Early reduction of the radial head with the modified approach may be a simple and primary option for emergency room doctors.

Complex Monteggia Fractures in the Adult Cohort: Injury and Management

Monteggia fractures involve proximal ulna fracture associated with a radiocapitellar joint dislocation. The Bado classification is primarily based on the direction of the radial head dislocation. The Jupiter subtype classification of Bado II fractures further characterizes the severity of proximal ulna comminution and the involvement of the coronoid fragment. This latter classification can better prognosticate the challenges of surgical reconstruction and clinical outcomes. Surgery for all adult Monteggia fractures is required to restore the anatomic alignment of the ulna, which indirectly reduces the radiocapitellar joint. The complexity of the injury is considerably increased by comminution of the proximal ulna, the degree of radial head fragmentation, the reduction of the radial head, and ulnohumeral instability. Anatomic reduction is considered critical to achieving a favorable outcome.

Biomechanical analysis of simultaneous distal and proximal radio-ulnar joint instability

BACKGROUND

Simultaneous dislocation of the proximal and distal radio-ulnar joints without bony injuries has been reported, but the mechanism remains unclear. We investigated concurrent proximal and distal radio-ulnar joint instability after sequential sectioning of the annular ligament, triangular fibrocartilage complex, and quadrate ligament.

METHODS

We performed this biomechanical study with six fresh-frozen cadaveric upper extremities. Proximal and distal radio-ulnar joint displacement was measured using an electromagnetic tracking device during passive mobility testing with anterior, lateral, and posterior loads on the radial head with pronation, supination, and neutral rotation. Measurements were statistically analyzed using the generalized linear mixed model.

FINDINGS

Proximal radio-ulnar joint instability was significantly greater after sectioning of the annular (lateral: 1.4%, P < .05; posterior: 0.7%, P < .05) and quadrate (lateral: 43.7%, P < .05; posterior: 29.5%, P < .05) ligament. Distal radio-ulnar joint instability was significantly greater in every sequential stage (final stage: anterior: 24.1%, P < .05; lateral 21.0%, P < .05; posterior: 31.3%, P < .05). Finally, significant simultaneous instability of the joints was observed after sectioning of the annular ligament, triangular fibrocartilage complex, and quadrate ligament, and neutral rotation potentially induced gross instability.

INTERPRETATION

Our ligament injury model induced simultaneous proximal and distal radio-ulnar joint instability without bony or interosseous membrane injury, probably induced by severe soft tissue injury. Proximal radio-ulnar joint instability may influence distal radio-ulnar joint instability from pivoting of the interosseous membrane. Our findings will help surgeons evaluate the magnitude of soft tissue injury and plan surgery for patients with simultaneous proximal and distal radio-ulnar joint instability.

Isolated Proximal Radioulnar Joint Instability: Anatomy, Clinical Presentation, and Current Treatment Options

Isolated proximal radioulnar joint instability is an uncommon and often challenging problem that may manifest as recurrent instability of the proximal aspect of the radius, usually during forearm pronation and supination. Instability is due to deficiency of the stabilizing structures around the proximal aspect of the radius, and biomechanical studies have highlighted the importance of the annular ligament and the interosseous membrane in both transverse and longitudinal plane stability. Reconstruction of the stabilizing structures around the radial head often is indicated in cases of recurrent instability and includes joint-preserving procedures such as annular ligament reconstruction, proximal ulnar osteotomy, and interosseous membrane reconstruction. Rarely, salvage procedures such as interpositional arthroplasty or 1-bone forearm reconstruction are necessary. A thorough understanding of the anatomic structures that stabilize the proximal aspect of the radius and the complexities of forearm biomechanics is required in order to successfully diagnose and manage this condition.

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

BACKGROUND

Radial head instability continues to be a challenge in the management of anterior Monteggia injuries; however, there is a paucity of literature on the factors that contribute to this instability. The aim of this biomechanical investigation was to examine the effects of ulnar angulation and soft tissue insufficiency on radial head stability in anterior Monteggia injuries.

METHODS

Six cadaveric arms were mounted in an elbow motion simulator. Radial head translation was measured during simulated active elbow flexion with the forearm supinated. After testing the elbows in the intact state, the ulna was osteotomized and tested at 0°, 10°, 20°, and 30° of extension angulation. To examine the effect of soft tissue insufficiency, the anterior radiocapitellar joint capsule, annular ligament, quadrate ligament, and the proximal and middle interosseous membrane (IOM) were sequentially sectioned.

RESULTS

There was a significant increase in anterior radial head translation with greater ulnar extension angulation. Sequential soft tissue sectioning also significantly increased anterior radial head translation. There was no increase in radial head translation with isolated sectioning of the anterior radiocapitellar joint capsule. Additional sectioning of the annular ligament and quadrate ligament slightly increased anterior radial head translation but did not reach statistical significance. Subsequent sectioning of the proximal and middle IOM resulted in significant increases in anterior radial head translation.

CONCLUSION

Our study demonstrates that progressive ulnar extension angulation results in an incremental increase in anterior radial head translation in anterior Monteggia injuries. Moreover, increasing magnitudes of soft tissue disruption result in greater anterior radial head instability.

Effect of soft tissue injury and ulnar angulation on radial head instability in a Bado type I Monteggia fracture model

The effects of soft tissue damage and ulnar angulation deformity on radial head instability in Monteggia fractures are unclear. We tested the hypothesis that radial head instability correlates with the magnitude of ulnar angular deformity and the degree of proximal forearm soft tissue injury in Bado type I Monteggia fractures.We performed a biomechanical study in 6 fresh-frozen cadaveric upper extremities. Monteggia fractures were simulated by anterior ulnar angulation osteotomy and sequential sectioning of ligamentous structures. We measured radial head displacement during passive mobility testing in pronation, supination, and neutral rotation using an electromagnetic tracking device. Measurements at various ligament sectioning stages and ulnar angulation substages were statistically compared with those in the intact elbow.Radial head displacement increased with sequential ligament sectioning and increased proportionally with the degree of anterior ulnar angulation. Annular ligament sectioning resulted in a significant increase in displacement only in pronation (P < .05). When the anterior ulnar deformity was reproduced, the radial head displaced least in supination. The addition of proximal interosseous membrane sectioning significantly increased the radial head displacement in supination (P < .05), regardless of the degree of anterior ulnar angulation.Our Monteggia fracture model showed that radial head instability is influenced by the degree of soft tissue damage and ulnar angulation. Annular ligament injury combined with a minimal (5°) ulnar deformity may cause elbow instability, especially in pronation. The proximal interosseous membrane contributes to radial head stability in supination, regardless of ulnar angulation, and proximal interosseous membrane injury led to significant radial head instability in supination.

A youngest reported case of type II Monteggia lesion associated with a posterior ulnohumeral dislocation

Monteggia fractures are uncommon injuries, despite a high incidence of upper limb fractures in teenage children. We describe a case of a type 2 Monteggia variant in an adolescent. This injury pattern consisted of ulnohumeral dislocation in combination with type 2 Monteggia lesion. We discuss the possible injury mechanisms of this rare injury and review available literature.

Apparent Proximal Ulna Dorsal Angulation Variation Due to Ulnar Rotation

OBJECTIVE

To investigate the effect of ulna rotation on the apparent proximal ulna dorsal angulation (PUDA).

METHODS

Computed tomography images of 59 ulnas were included in this study, 48 being bilateral specimens and the remaining 11 were unilateral. Three-dimensional models of the entire ulna were obtained, and the ulnas were rotated in 5-degree increments in internal rotation or external rotation from neutral. PUDA, PUDA apex, varus angulation, and varus apex were measured on each ulna.

RESULTS

With the ulna in neutral rotation, the mean (95% CI) PUDA was 3.7 (2.9-4.5) degrees, whereas the mean varus angle was 10.5 (9.8-11.1) degrees. The varus angle apex and PUDA apex were 28.9 (27.5-30.2)% and 19.6 (18.7-20.6)% along the total length of the ulna, respectively. As the ulna was rotated externally by 5, 10, and 15 degrees, the PUDA increased by 0.7 (0.5-0.9) degrees, 1.2 (0.9-1.4) degrees, and 1.4 (1.1-1.8) degrees, respectively. Conversely, with internal rotation of 5, 10, and 15 degrees, the PUDA decreased by 0.9 (0.8-1.1) degrees, 2.0 (1.8-2.3) degrees, and 3.3 (2.7-3.9) degrees, respectively.

CONCLUSIONS

This study demonstrates that small degrees of ulna rotation result in a statistically significant change in the apparent PUDA; however, this may not represent a clinically significant difference. Because of the anatomic variation between patients, it is important to obtain a contralateral film to determine the PUDA for anatomic reduction of the ulna in complex cases. When using a contralateral image, it is important to obtain a true lateral film or consider using 3-dimensional imaging for preoperative planning.

Ipsilateral Pediatric Supracondyar Humerus Fracture and Radial Head Dislocation

Case: A 5-year-old boy presented with left elbow pain after a fall. Radiographs revealed a radial head dislocation without ulnar involvement which was treated with closed reduction in the emergency department. Two-week follow-up radiographs revealed a periosteal reaction along the medial epicondyle at the supracondylar region, consistent with a type 1 supracondylar humerus fracture. The elbow was treated with closed reduction and casting for 2 weeks. One year after injury, the patient had full painless range of motion. Conclusion: This case report highlights an injury pattern not previously described in the literature, and no previous recommendations exist regarding treatment. Although rare, radial head dislocation with simultaneous supracondylar humerus fracture can occur in pediatric patients. Our patient obtained a good result without surgical treatment.

Annular ligament reconstruction in chronic Monteggia fracture-dislocations in the adult population: indications and surgical technique

Chronic Monteggia fracture is defined as dislocation of the radial head that is still present 4 weeks after injury. The cause may reside in residual ulnar deformity after internal fixation, in failure of annular ligament healing, or both. This situation may lead to elbow pain, decreased motion, neurologic problems and valgus deformity. The aim of the present study is to investigate indications and surgical technique for annular ligament reconstruction (ALR) in chronic Monteggia fractures. Relevant articles on annular ligament anatomy and biomechanics, clinical-radiographic evaluation of chronic Monteggia lesions and surgical techniques for ALR were reviewed. A case of an ALR in chronic Monteggia injury using a modified Bell Tawse surgical technique with triceps tendon autograft is presented. Little data exist on chronic Monteggia injury in the adult population. The annular ligament has a critical role in radial head stability. Nonetheless, bony alignment of the ulna is confirmed to be the most relevant feature to address in chronic Monteggia fractures. ALR has been advocated to address radial head instability both combined with ulna osteotomy and as a single procedure, with several surgical techniques described and controversial results reported. A modified Bell Tawse surgical technique resulted to be effective in the presented case. ALR seems to be indicated in chronic Monteggia fractures with normal bony alignment, without conclusive evidence on a preferable surgical technique.

Anterior Dislocation of the Radial Head Combined with Plastic Deformity of the Ulnar Shaft in an Adult: A Case Report

A 25-year-old woman presented to the emergency room with a painful and swollen right forearm. She had just sustained an injury from an accident during which her arm was tightly wound by a rope as she was lowering a net from a fishing boat. Before being released, her arm was rigidly trapped in the rope for approximately ten minutes. Radiographs revealed anterior dislocation of the radial head that was accompanied by plastic deformation of the proximal ulna, manifested as a reversal of the proximal dorsal angulation of the ulna (PUDA); suggested a Monteggia equivalent fracture. With the patient under general anesthesia, we reduced the radial head by posterior compression at 90° of elbow flexion and at neutral rotation of the forearm. However, the reduction was easily lost and the elbow re-dislocated with even slight supination or extension of the arm. After the osteotomy of the ulnar deformity to restore the PUDA to normal, the reduction remained stable even with manipulation of the arm. We found that the patient could exercise a full range of motion without pain at the 3-month follow-up, and neither residual instability nor degenerative changes were observed at the final 3-year follow-up.

Annular ligament reconstruction with the superficial head of the brachialis: surgical technique and biomechanical evaluation

PURPOSE

The purpose of this study was to perform biomechanical testing of annular ligament (AL) reconstruction using the superficial head of the brachialis tendon (SHBT) as a distally based tendon graft. We hypothesized that posterior translation of the radial head following AL reconstruction with an SHBT graft does not significantly differ from intact specimens.

METHODS

Six fresh-frozen elbow specimens were used. The stability of the radial head against posterior translation forces (30 N) was evaluated in 0°, 45°, 90° and 120° of elbow flexion. Posterior translation was obtained for the intact AL, the sectioned AL and the reconstructed AL. Cyclic loading (100 cycles) in 90° of elbow flexion was performed for the intact and the reconstructed AL.

RESULTS

Posterior translation of the radial head decreased during elbow flexion in native specimens. Sectioning of the AL significantly increased instability over the full range of motion. AL reconstruction with the SHBT restored the stability of the proximal radius but-other than the native AL-was not influenced by elbow flexion. In 120° of flexion the native AL provided significantly more stability when compared to the reconstructed AL. Cyclic loading did not provide significant differences between native and reconstructed specimens.

CONCLUSIONS

We provide a feasible technique for AL reconstruction using the SHBT. The biomechanical results obtained in this study confirm the efficacy of the procedure. AL reconstruction restores the stability of the proximal radius, yet it cannot fully mimic the complex features of the intact AL.

Impact of olecranon fracture malunion: Study on the importance of PUDA (Proximal Ulna Dorsal Angulation)

PURPOSE

The Proximal Ulna Dorsal Angulation (PUDA) is part of the proximal ulna's normal anatomy. The importance of restoring ulnar anatomy characteristics precisely after olecranon fracture is not known, however, failure to recreate the PUDA after surgery may result in poorer functional outcomes. The purpose of this study is to evaluate the impact of minimal proximal ulna malunion on elbow ROM and function at least one year after olecranon ORIF.

METHOD

A retrospective comparative cohort study took place in three level-1 trauma centers. Forty-nine adult volunteers who underwent ORIF for olecranon fracture were included. Patients were separated into two groups according to PUDA malreduction-defined as more than 5° of difference between the fractured and the contralateral elbow.

OUTCOME MEASUREMENTS

Radiographic ROM measurement, demographic data and quality of life questionnaires were recorded (PREE, MEPS, Q-DASH, SF12, VAS).

RESULTS

The mean follow up was 3 years and 9 months (1-7 years). There was no difference in terms of outcome, quality of reduction or range of motion between patients treated with plate or tension band. The mean PUDA on the fracture side was different from the normal side (2.20 vs 4.90, p<0.001). Fourteen patients (29%) had PUDA malunion. Those patients had decreased elbow flexion (-7°, p=0.011), extension (-11.2°, p=0.013) and total ROM (-18.6°, p=0.006) as opposed to the control group. Both groups had comparable quality of life questionnaire scores. Alcohol consumption was the only risk factor associated with worse scores.

CONCLUSION

Incidence of olecranon malunion-as defined by PUDA measurement - was 29% and it was associated with decreased elbow range of motion. Alcohol consumption was correlated with a worse prognosis in our series of patients. Tension band and plate fixation can maintain a good reduction in terms of PUDA and the choice of fixation method does not influence outcome.

LEVEL OF EVIDENCE

III Therapeutic study.