What Injury Mechanism and Patterns of Ligament Status Are Associated With Isolated Coronoid, Isolated Radial Head, and Combined Fractures?

Fracture of the Anteromedial Facet of the Coronoid is More Common Than Previously Thought in Combined Fractures of the Coronoid and Radial Head

BACKGROUND

The terrible triad injury involves an ulnohumeral dislocation, radial head fracture, and coronoid process fracture. According to traditional teaching, these injuries are strongly associated with anterolateral coronoid tip fractures and can be addressed via a lateral approach to the elbow. However, recent small clinical series suggest that some terrible triad injuries have larger coronoid fractures involving the anteromedial facet. It is important to understand how often these larger coronoid fractures occur because anteromedial facet fractures may need a different approach and different implants for fixation. An improved understanding of coronoid fracture morphology in terrible triad injuries may help surgeons construct a surgical plan.

QUESTIONS/PURPOSES

To better define coronoid fracture morphology in combined coronoid and radial head fractures, we therefore asked: What is the distribution of anterolateral facet versus anteromedial facet coronoid fragments in combined coronoid and radial head fractures without an ulnar shaft fracture?

METHODS

This retrospective, multicenter descriptive study evaluated preoperative CT scans from adult patients (18 years or older) diagnosed with combined coronoid and radial head fractures. Between February 2014 and March 2023, we identified 10,016 adult patients with elbow or forearm injuries who underwent CT scans. Among these patients, we considered those diagnosed with combined coronoid and radial head fractures without an ulnar shaft fracture based on elbow CT scans performed within 4 weeks of the injury as potentially eligible. During that time, elbow CT scans were generally ordered to assess complex fractures, confirm diagnoses when radiographs were inconclusive, evaluate joint involvement, or plan for surgical interventions. Based on that, 2% (175 of 10,016) were eligible; a further 0.001% (8 of 10,016) were excluded because of preexisting elbow pathology, prior surgery, or low-quality CT images (including slice thickness greater than 2 mm, motion artifacts, and incomplete visualization of the osseous structure of the elbow and all its articulations), leaving 2% (167 of 10,016) for analysis. The mean age was 50 ± 15 years, and more than half of the patients were female (54% [90 of 167]). Coronoid fractures in patients with combined coronoid and radial head fractures were classified using the O'Driscoll classification into three types: Type 1 (anterolateral tip fractures), Type 2 (anteromedial facet fractures), and Type 3 (base fractures). Each type was further subcategorized based on specific fracture characteristics. Two of three trained researchers independently classified the coronoid fracture type of each patient using radiographs, two-dimensional (2D) CT scans, three-dimensional (3D) CT scans, and intraoperative findings, with interrater reliability assessed by the Cohen kappa, yielding a substantial agreement value of 0.658. Disagreements were resolved through discussions with a fellowship-trained orthopaedic trauma surgeon.

RESULTS

Sixty-five percent (109 of 167) of patients had a Type 1 anterolateral coronoid tip fracture, 30% (50 of 167) had a Type 2 anteromedial facet fracture, and 5% (8 of 167) had a Type 3 basal fracture.

CONCLUSION

Surgeons should recognize that anteromedial facet involvement in coronoid fractures is more prevalent in combined coronoid and radial head fractures than previously appreciated. Future research should investigate whether these anteromedial fractures are more likely to need an additional medial approach to improve patient outcomes.

CLINICAL RELEVANCE

This study suggests that anteromedial facet involvement is more common than traditionally recognized in terrible triad injuries, and surgeons should be prepared to address a larger fragment when treating these injuries.

Three-dimensional quantitative study and functional outcome analysis of coronoid fracture in different elbow injury patterns

BACKGROUND

Coronoid fractures are often part of a complex fracture-dislocation of the elbow. For an optimum prognosis, it is important to understand the characteristics of coronoid fractures in different elbow injury patterns. Significant differences in these characteristics have been observed in various studies, but these previous studies have suffered from limitations, such as insufficient quantification and unknown prognostic differences among different injury patterns. Therefore, we aimed to quantitatively analyze coronoid fracture characteristics and functional outcomes in different elbow injury patterns using three-dimensional computed tomography.

METHODS

All patients with coronoid fractures surgically treated at our hospital between January and December 2017 were categorized into 3 groups according to elbow injury pattern: posterolateral rotational instability (PLRI), varus posteromedial rotational instability (VPMRI), and olecranon fracture-dislocation (OFD). 3D models were reconstructed using Mimics 17.0, and the total volume and number of coronoid fragments were measured. The coronoid process edge was classified into different anatomical regions, and each region was assigned a number to quantify the distribution of fracture lines. At the last follow-up, the range of motion, visual analog scale, Mayo Elbow Performance Score, complications and reoperations were recorded.

RESULTS

The 92 patients enrolled had an average age of 42 ± 15 years and a male-to-female ratio of 66:26. The median total volume in PLRI patients was less than that in VPMRI patients [431 (132, 818) mm3 vs. 1125 (746, 1421) mm3, adjusted P < .001] and OFD patients [431 (132, 818) mm3 vs. 2565 (381, 4076) mm3, adjusted P = .001]. The median number of coronoid fragments in PLRI patients was also less than that in VPMRI patients [1 (1, 2) vs. 2 (1, 3), adjusted P = .043]. Most of the PCFL-Rs (79%) were located around the volar edge of the lesser sigmoid notch. Compared with that of PLRI, the PCFL-Us of the VPMRI and OFD tended to be located on the more ulnodorsal side of the coronoid process edge. The median ROM [110 (90, 133), P = .001] and the median Mayo Elbow Performance Score [85 (68, 95), P = .038] of patients with OFD were significantly less than those of patients with the other 2 patterns. The incidence of elbow stiffness (56%, 5/9, P = .001) and implant-related irritation (44%, 4/9, P < .001) in the OFD group was significantly higher than that in the other 2 groups.

CONCLUSION

Coronoid fractures differ significantly in fragment volume, comminution severity, and fracture line distribution among different elbow injury patterns. OFD has the worst functional outcomes among complex elbow injury patterns.

Comprehensive classification and its value of capitellar cartilage injury concomitant with radial head fracture

BACKGROUND

There are defects in the existing classification of capitellar cartilage injury (CCI) concomitant with radial head fracture (RHF). This study aimed to introduce a comprehensive classification of CCI and to analyze its surgical guidance value.

METHODS

According to the affected site and severity, CCI was classified into four types: Type I - partial-thickness loss of articular cartilage, Type II - full-thickness loss of articular cartilage, Type III - full-thickness loss of articular cartilage with subchondral bone loss, Type IV - full-thickness loss of articular cartilage with thin cortex loss on the border of the capitellum; Different types suggest different surgical methods. Between January 2017 and January 2023, this comprehensive CCI classification was applied in 31 operated patients with CCI concomitant with RHF. The ranges of motion (ROM), Mayo Elbow Performance Index (MEPI) score, Hospital for Special Surgery (HSS) score and visual analog scale (VAS) for pain, were used to evaluate the functional recovery of the affected limb.

RESULTS

Mason Type I-IV RHF accounted for 6.45%, 38.71%, 48.39%, and 6.45%, respectively. Type I-IV CCI accounted for 12.90%, 35.48%, 45.16% and 6.45%, respectively. There was no relationship between the CCI and RHF types (p > 0.05). At the end of the follow-up period of 11-26 months with an average of 16 months, the elbow flexion and extension ROM recovered to (147.39 ± 9.84)°, forearm rotation ROM recovered to (168.74 ± 11.70)°, MEPI score recovered to (89.19 ± 4.17), HSS score recovered to (88.74 ± 4.62), VAS score recovered to (0.50 ± 0.57), indicating significant differences compared to preoperative measurements (p < 0.05). According to the MEPI and HSS scores, the excellent and good rate of functional recovery was 100%.

CONCLUSION

Different types of CCI differ not only in pathology but also in treatment methods. Surgical strategy according to the comprehensive CCI classification introduced in this paper may lead to a satisfactory outcome.

Morphometrics of the coronoid process and the radial notch of the ulna: implications for fracture assessment

PURPOSE

A comprehensive analysis of the morphology of fractures of the coronoid process (CP) can aid diagnosis and guide treatment. The involvement of the radial notch of the ulna (RN)-e.g., in anterolateral facet fractures and transverse fractures of the CP-may influence the biomechanical conditions of the proximal radioulnar joint. However, the morphometric relation between the CP and the RN and the extent to what the proximal radioulnar joint can be affected in these types of fractures is unknown.

METHODS

A total of 113 embalmed, cadaveric ulnae were dissected. All soft tissue was removed. Strictly lateral, high-resolution photographs were taken and digitally analyzed. The height of the CP and its relation to the RN was measured. Sex differences and correlations between measured parameters were calculated.

RESULTS

Mean height of the CP was 16 mm (range: 12-23 mm; SD: 2). Mean height of the RN was 16 mm (11-25 mm; 2.2). The 50% mark of the CP corresponded to 18% (0-56%; 11.2) of the height of the RN. No significant differences were found between male and female specimens.

CONCLUSION

The RN of the ulna extends only to a small part to the CP. Transverse or anterolateral fractures of less than 50% of the coronoid process may involve only a small portion of the proximal radioulnar joint.

Comparison of buttress plate and cannulated screw in the treatment of anteromedial coronoid fracture with elbow posteromedial rotatory instability

PURPOSE

The purpose of this study is to compare the effect of buttress plate and cannulated screw in the treatment of anteromedial coronoid fracture with posteromedial rotatory instability (PMRI).

METHODS

We retrospectively evaluated patients who were diagnosed with O'Driscoll type 2 fractures combined with elbow posteromedial rotatory instability and underwent surgery for anteromedial coronoid fracture between August 2014 and March 2019. They were divided into buttress plate (n=16) and cannulated screw (n=11) groups. The elbow range of motion, visual analog scale (VAS), Mayo elbow performance score (MEPS), and disabilities of the arm, shoulder, and hand score (DASH) were used for clinical outcome assessment.

RESULT

There were no significant differences in clinical outcomes. However, the surgical time was significantly shorter in cannulated screw group (85.45±4.156) compared to the buttress plate group (93.81±8.863, P=0.008), and the surgical time was associated with internal fixation (P=0.008).

CONCLUSION

Although there was selection of cases in that small fragments were treated with buttress plate and large fragments with cannulated screw, the buttress plate and cannulated screw have comparable functional outcomes on fixation of the anteromedial coronoid fracture with elbow PMRI. The fixation of the anteromedial coronoid fracture with large fragments using the cannulated screw has a shorter operation time.

A Novel Suture-Preset Spring Plate System (SSPS) for Comminuted Coronoid Process Fracture in the Elbow

OBJECTIVE

This study is aimed to investigate the clinical outcomes of a novel SSPS for fixation of the comminuted coronoid fracture.

METHODS

A retrospective study was carried out in the patients with comminuted fractures of the coronoid treated by SPSS fixation between January 2014 and December 2018. A total of 17 patients (17 sides) was included in our study, including 11 male and six female, with a mean age range from 18 to 60. All cases started to functional rehabilitation immediately after the operation. Clinical outcomes were evaluated both radiographically and functionally at the follow-up visit, including the elbow instability, range of motion and Mayo elbow performance score (MEPS).

RESULTS

According to the O'Driscoll classification system, there was two side of type 1.2, two of type 2.1, four of type 2.2, three of type 2.3, two of 3.1 and four of type 3.2. The surgery was carried out by Kocher and anteromedial approach in 12 patients, posterior and anteromedial approach in four, anterior approach in one. The average operation time and intraoperative blood loss was 129.41±43.87 min and 115.29±104.65 ml. The median follow-up time was 9 months (range, 6 to 15 months). The mean flexion, extension, pronation and supination motion was 138.76±8.67 degrees, 20.00±13.58, 82.94±5.32and 74.12±14.39 respectively at final follow up. The mean MEPS score was 89.76±8.46, including 11 excellent, 3 good and 3 fair result. The mean VAS score was 1.94±0.97. The mean union time of coronoid fractures was 2.77±0.31 months according to the established standard of healing. There were no significant differences in clinical outcomes among groups according to the O'Driscoll classification (P > .05) and ligament repair strategy (P > .05). No patient underwent instability or dislocation of the elbow during follow up. There were two cases with mild ulnar nerve symptoms which recovered totally at follow up. Meanwhile, there were three cases with heterotopic ossification of the elbow.

CONCLUSION

Our findings demonstrated that the SSPS can provide a reliable fixation for the comminuted coronoid fracture with satisfactory clinical outcomes.

Acute Ligament Injuries of the Elbow

Ulnar collateral, radial collateral, lateral ulnar collateral, and annular ligaments can be injured in an acute trauma, such as valgus stress in athletes and elbow dislocation. Recognizing normal anatomy in magnetic resonance imaging and ultrasonography studies is important to identify ligamentous abnormalities in these imaging modalities.

Patterns of injury mechanism observed in terrible triad

INTRODUCTION

The purpose of this study was to classify the injury mechanism of terrible triad (TT) and suggest a treatment method according to the mechanism.

MATERIALS AND METHODS

Forty TTs with magnetic resonance imaging (MRI) scans and 3-dimensional computed tomography (3D CT) were enrolled. 3D CT scans of coronoid fractures were used for classifying into O'Driscoll type representing injury mechanisms and measuring sizes. In MRI scans, lateral collateral ligament complex (LCLC) injuries were classified into distraction (D) type caused by varus force and stripping (S) type caused by forearm external rotation force. Using these findings, possible injury mechanisms were speculated and classified into groups. Characteristic soft tissue injury patterns of collateral ligaments and overlying muscles, direction of dislocation in simple radiographs, and the amount of involvement of radial head fracture were investigated. Ulnar- and radial-side instabilities of soft tissues were newly defined and investigated.

RESULTS

There were 29 (73%) cases by posterolateral external rotation (PLER), 5 (13%) cases by posteromedial external rotation (PMER), and 6 (14%) cases by posteromedial internal rotation (PMIR). Simple radiographs showed all posterolateral dislocations in PLER TT compared to posteromedial or pure posterior dislocations in PMER or PMIR TT. Regarding LCLC and overlying extensor muscle, they were all completely torn with D type in all PLER compared to D type in PMER or PMIR. The ulnar collateral ligament was spared in 5 (17%) cases among 29 PLER in contrast to complete rupture in all PMER and PMIR. In PLER, PMER, and PMIR, involvement ratios of radial head fracture were 82% (range, 27%-100%), 61% (range, 25%-100%), and 61% (range, 25%-100%), respectively, and sizes of coronoid fractures were 7 mm (range, 1-14 mm), 6 mm (range, 2-11 mm), and 10 mm (range, 2-16 mm), respectively. In PLER, PMER, and PMIR, percentages of ulnar-side instabilities were 17%, 20%, and 17%, respectively, and those of radial-side instabilities were 59%, 60%, and 83%, respectively.

CONCLUSIONS

TT is caused by at least 3 mechanisms (PLER, PMER, and PMIR) with characteristic soft tissue injuries and fracture patterns. PLER is the main mechanism of injury. It is always observed in the form of posterolateral dislocation on simple radiographs compared with pure posterior or posteromedial dislocation of PMER or PMIR. It should be managed individually based on injury mechanisms presenting different instability patterns.

Analysis of Fracture Characteristic and Medial Collateral Ligament Injury Relationships in Terrible Triad Elbow Injuries

PURPOSE

The objectives of this study were to identify the relationship between fracture characteristics and medial collateral ligament (MCL) injuries in terrible triad injuries of the elbow.

METHODS

Between 2010 and 2018, 60 patients who underwent surgery for terrible triad elbow injuries were retrospectively reviewed. Using magnetic resonance imaging (MRI) assessments, patients were stratified into those who had intact or low-grade partial MCL tears (low-grade MRI-MCL group) and those who had high-grade partial or full-thickness MCL tears (high-grade MRI-MCL group). We also analyzed patients according to whether they underwent MCL repair surgery. Fractures of the radial head were assessed according to Mason's classification system and measurements of fracture fragment arc on axial cuts. Fractures of the coronoid processes were assessed according to the system of Regan and Morrey and measurements of coronoid process volumes.

RESULTS

Patients in the high-grade MRI-MCL group (28 patients) had a more comminuted and higher fragment arc of radial head fractures than those in the low-grade MRI-MCL group (32 patients) (143º ± 45º vs 119º ± 31º). However, the volume of coronoid fracture fragments was smaller in the high-grade MRI-MCL than in the low-grade MRI-MCL group (359 ± 325 mm³ vs 722 ± 448 mm³). The MCL repair group (22 patients) also had a more comminuted and higher fragment arc in radial head fractures (153º ± 44º vs 117º ± 31º) and a smaller coronoid process fracture volume (236 ± 224 mm³ vs 735 ± 419 mm³) than the non-MCL repair group (38 patients).

CONCLUSIONS

Our results demonstrated that high-grade MCL injuries are associated with comminuted and larger-sized radial head fractures, as well as smaller-sized coronoid process fractures in terrible triad injuries. In making a decision regarding surgical treatment, these fracture characteristics could help to predict the severity for MCL injury in terrible triad injuries.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Differences in Rupture Patterns and Associated Lesions Related to Traumatic Distal Triceps Tendon Rupture Between Outstretched Hand and Direct Injuries

BACKGROUND

Traumatic distal triceps tendon rupture results in substantial disability in the absence of an appropriate diagnosis and treatment. To the best of our knowledge, differences in the degree of injury according to the injury mechanisms and associated lesions are not well known.

QUESTIONS/PURPOSES

In this study, we asked: (1) What differences are seen in triceps tear patterns between indirect injuries (fall on an outstretched hand) and direct injuries? (2) What are the associated elbow and soft tissue injuries seen in indirect and direct triceps ruptures?

METHODS

Between 2006 and 2017, one center treated 73 elbows of 72 patients for distal triceps tendon rupture. Of those, 70% (51 of 73 elbows) was excluded from this study; 8% (6 of 73) were related to systemic diseases, 59% (43 of 73) sustained open injuries, and 3% (2 of 73) were related to local steroid injections. We retrospectively collected data on traumatic distal triceps tendon rupture in 30% (22 of 73) of elbows at a single trauma center during a 10-year period. A fall on an outstretched hand was the cause of injury in 15 patients and direct blow by object or contusion were the cause in seven. MRI and surgery were performed in all patients. Traumatic distal triceps tendon rupture was classified by the Giannicola method, which is classified according to the depth and degree of the lesion based on MRI and surgical findings. Associated fractures and bone contusions on MRI were characterized. Ligament injuries on MRI was divided into partial and complete rupture. Agreement between the MRI and intraoperative findings for the presence of a traumatic distal triceps tendon rupture was perfect, and the Giannicola classification of traumatic distal triceps tendon rupture was good (kappa = 0.713).

RESULTS

In the indirect injury group (fall on an outstretched hand), 15 of 15 patients had injuries that involved only the tendinous portion of the distal triceps, but these injuries were not full-thickness tears, whereas in the direct injury group, three of seven patients had a full-thickness rupture (odds ratio [OR] 1.75 [95% CI 0.92 to 3.32]; p = 0.02). The direct injury group had no associated ligamentous injuries while 14 of 15 patients with indirect injuries had ligamentous injuries (OR 0.13 [95% CI 0.02 to 0.78]; p < 0.001; associated injuries in the indirect group: anterior medial collateral ligament [14 of 15], posterior medial collateral ligament [7 of 15], and lateral collateral ligament complex [2 of 15]). Similarly, one of seven patients in the direct injury group had a bone injury (capitellar contusion), whereas 15 of 15 patients with indirect ruptures had associated fractures or bone contusions (OR 16.0 [95% CI 2.4 to 106.7]; p < 0.001).

CONCLUSION

A fall on an outstretched hand may result in an injury mostly to the lateral and long head of distal triceps tendon and an intact medial head tendon; however, direct injuries can involve full-thickness ruptures. Although a traumatic distal triceps tendon rupture occurs after a fall on an outstretched hand, radial neck, capitellar, and medial collateral ligament injury can occur because of valgus load and remnant extensor mechanisms. Based on our finding, the clinician encountering a distal triceps tendon rupture due to a fall on an outstretched hand should be aware of the possibility of remaining elbow extensor mechanism by intact medial head tendon portion, and associated injuries, which may induce latent complications.

LEVEL OF EVIDENCE

Level III, prognostic study.

The pronator teres and the flexor carpi radialis interval approach for operative fixation of ulna coronoid process fractures

BACKGROUND

The optimal approach for the fixation of coronoid process fractures is unknown. We present the advantages and the clinical effect of the pronator teres and the flexor carpi radialis interval approach for the treatment of ulna coronoid process fractures.

METHODS

The patients, who had operative treatment of closed ulna coronoid process fracture by the pronator teres and the flexor carpi radialis interval approach between January 2011 to December 2016, were studied retrospectively. Seventeen consecutive patients had received surgical fixation by screws or a mini-plate through the above approach, of whom were 16 males and one female with an average age of 36.7 years (range, 21-58 years). There were 11 cases of type II and 6 cases of type III according to the O'Driscoll classification, of which, 6 patients had combined elbow dislocation, 2 patients showed elbow instability after fixation, and one had another incision to repair the lateral collateral ligament, and received a hinged external fixator. The other patient only received a hinged external fixator for 4 weeks. Mayo Elbow Performance Score (MEPS) was used to assess the function of elbow for each patient at the final follow-up.

RESULTS

Mean follow-up was 28.7 months (range, 24-38 months). Fracture union was achieved in each patient; the average time to radiologic union was 14.2 weeks (range, 12-16 weeks). At the final follow-up, the elbow extension degree of the affected side was (3.88±2.96°), reaching 98.1% of the normal side, and the flexion degree was (131.59±4.93°), reaching 98.16% of the normal side. The forearm pronation was (82.94±3.86°), reaching 94.31% of the normal side, and the supination activity was (82.12±3.82°), reaching 93% of the normal side. According to the MEPS, the functional recovery of the injured arm was assessed as excellent in 16 cases, and good in one. None of the patients showed any neurovascular or deep infections and no heterotopic ossification was found.

CONCLUSIONS

The pronator teres and the flexor carpi radialis interval approach has the advantages of simplicity, safety, minimal invasion, excellent exposure, and good postoperative function recovery for ulna coronoid process fracture.

Biomechanical comparison of screw osteosyntheses and anatomical plating for coronoid shear fractures of the ulna

INTRODUCTION

Among the few techniques described for the treatment of coronoid fractures, osteosynthesis techniques include screw osteosynthesis from anterior to posterior (AP) or from posterior to anterior (PA) and plate osteosynthesis. The aim of this study was to test the biomechanical stability of screw osteosynthesis and plate osteosynthesis using anatomical plates in coronoid process fractures.

MATERIALS AND METHODS

On a total of 25 biomechanical synthetical ulnae, a coronoid shear fracture including 70% of the coronoid height was simulated. Osteosynthesis was then performed using two 2.7 mm screws from anterior, posterior and with use of three different anatomical plates of the coronoid process. For the biomechanical testing, axial load was applied to the fragment with 1000 cycles from 5 to 250 N, load to failure and load at 100 µm displacement. Displacements were measured using a point-based three-dimensional motion analysis system.

RESULTS

Osteosynthesis using the PA-screw showed significant more displacement during cyclic loading compared with all other osteosyntheses (0.99 mm), whereas AP-screw showed the smallest displacement (0.10 mm) during cyclic loading. The PA-screw technique showed a significant lower load to failure compared to all other osteosynthesis with the highest load in AP-screw osteosynthesis. The load for 100 µm displacement was the smallest in PA-screw with a significant difference to the AP-screw and one plate osteosynthesis.

CONCLUSION

Osteosynthesis of large coronoid shear fractures with two small-fragment screws from anterior allows stable fixation that is not inferior to anterior plate osteosynthesis and might be an alternative in specific fracture types. Posterior screw fixation was found as the weakest fixation method.

LEVEL OF EVIDENCE

Basic science study.

Injuries to the Coronoid Process of the Ulna with Involvement of the Lesser Sigmoid Notch

INTRODUCTION

This study aimed to describe the involvement of the lesser sigmoid notch in fractures to the coronoid process. We hypothesized that injuries to the lateral aspect of the coronoid process regularly involve the annular ligament insertion at the anterior lesser sigmoid notch.

MATERIAL AND METHODS

Patients treated for a coronoid process fracture at our institution between 06/2011 and 07/2018 were included. We excluded patients < 18 years, patients with arthritic changes or previous operative treatment to the elbow, and patients with concomitant injuries to the proximal ulna. In patients with involvement of the lesser sigmoid notch, the coronoid height and fragment size (anteroposterior, mediolateral, and craniocaudal) were measured.

RESULTS

Seventy-two patients (mean age: 47 years ± 17.6) could be included in the study. Twenty-one patients (29.2%) had a fracture involving the lateral sigmoid notch. The mean anteroposterior fragment length was 7 ± 1.6 mm. The fragment affected a mean of 43 ± 10.8% of the coronoid height. The mean mediolateral size of the fragment was 10 ± 5.0 mm, and the mean cranio-caudal size was 7 ± 2.7 mm.

CONCLUSION

Coronoid fractures regularly include the lesser sigmoid notch. These injuries possibly affect the anterior annular ligament insertion which is important for the stability of the proximal radioulnar joint and varus stability of the elbow.

Elbow Fractures

The elbow joint consists of the humeroulnar, humeroradial, and proximal radioulnar joints. Elbow stability is maintained by a combination of static and dynamic constraints. Elbow fractures are challenging to treat because the articular surfaces must be restored perfectly and associated soft tissue injuries must be recognized and appropriately managed. Most elbow fractures are best treated operatively with restoration of normal bony anatomy and rigid internal fixation and repair and/or reconstruction of the collateral ligaments. Advanced imaging, improved understanding of the complex anatomy of the elbow joint, and improved fixation techniques have contributed to improved elbow fracture outcomes.

Reliability of dynamic fluoroscopy for medial elbow stability in the presence of radial head resection

Background

The aim of this study was to examine whether dynamic fluoroscopy is reliable for assessment of medial elbow stability in the presence of radial head resection and different stages of medial collateral ligament (MCL) dissection in a cadaveric elbow model.

Materials and methods

Six intact elbow specimens were measured for joint angulation while applying valgus stress in four examination conditions (Examiner 1, Examiner 2, 1 Nm, 2 Nm) in four different elbow positions (fully pronated or supinated at 0° of elbow extension and 30° of elbow flexion). The elbow specimens were examined for valgus stress in three stages: (1) intact, (2) after radial head resection, and (3) after subsequent dissection of the complete MCL. Anteroposterior radiographs of the elbow were made at each stage to determine joint angulation. Intraclass correlation coefficients (ICCs) were calculated.

Results

In intact elbows, mean joint angulation ranged from 2.2° ± 2.0 (1 Nm) to 5.2° ± 2.3 (Examiner 1). Radial head resection did not increase joint angulation during valgus stress, regardless of joint position and examination condition (Examiner 1: 5.5°; Examiner 2: 5.0°; 1 Nm: 2.6°, 2 Nm: 3.9°). Additional dissection of the MCL led to significantly higher joint angulation during measurements with the standardized torques (1 Nm: 12.4°; 2 Nm: 23.3°). Very good to excellent ICCs for joint angulation between Examiner 1 and Examiner 2 (0.861 to 0.959) were found.

Conclusion

Dynamic fluoroscopy is a reliable diagnostic tool for determining medial elbow stability in the presence of radial head resection and different stages of MCL dissection.

[Plate osteosynthesis of the coronoid process of the ulna]

OBJECTIVE

The aim of surgical treatment is reconstruction of the coronoid process' bony anatomy.

INDICATIONS

Large shear fractures of the coronoid process (Regan-Morrey type II-III, O'Driscoll "tip" subtype 2 and "basal" subtype 1-2) and fractures of the anteromedial facet (O'Driscoll "anteromedial" subtype 1-3) can occur isolated or as part of the "terrible triad" injuries to the elbow. Due to the resulting instability of these injuries, surgical reconstruction is generally indicated.

CONTRAINDICATIONS

In case of major accompanying soft tissue injuries to the elbow or an elbow infection, primary operative treatment using anatomical plate osteosynthesis is contraindicated.

SURGICAL TECHNIQUE

Plate osteosynthesis of the coronoid process is performed through a medial approach (Hotchkiss or M. flexor carpi ulnaris split). After repositioning of the fracture fragments, a preformed anatomical plate can be fixed to the coronoid process.

POSTOPERATIVE MANAGEMENT

The arm is immobilized in an over-the-elbow cast until the wounds are dried. Afterwards, the elbow should preferably be treated functionally without varus or valgus stress.

RESULTS

Between January 2015 and July 2018, a total of 11 patients underwent osteosynthesis of the coronoid using anatomically preformed plate osteosynthesis. After a mean follow-up of 10.7 months, the mean Mayo Elbow Performance Score showed an excellent result with 78.89 points. The Quick Disabilities of Arm, Shoulder and Hand (Q-DASH) score showed a median of 18.64 points with a mean functional arc of 118°.

Transverse capitellar shear fracture with interposed radial head fragment. A previously unclassified type of distal humeral fracture

This is the first description of a transverse shear fracture on the radial capitellum. So far only fractures in the frontal plane have been classified. MRI examinations in radial head fractures type Mason II–III shows that osteocondral fractures of radial capitellum are much more common than previously thought (10–30%). Treatment of this type of fracture is similar to frontal shear fractures.

Insertional anatomy of the anterior medial collateral ligament on the sublime tubercle of the elbow

BACKGROUND

Acute injuries to the anterior medial collateral ligament (AMCL) can occur due to valgus trauma or during other dislocating events to the elbow. AMCL lesions are often associated with bony lesions, such as radial head fractures or fractures of the coronoid process. We analyzed the insertion of the AMCL on the sublime tubercle in relation to surrounding osseous structures. We aimed to increase the understanding of the involvement of the AMCL in bony lesions to the sublime tubercle.

METHODS

We investigated 86 elbows from 43 embalmed human specimens. We measured the most ventral extensions of the AMCL at the sublime tubercle in relation to a clearly defined and reproducible landmark. We used as our landmark a horizontal line (baseline) originating on the lesser sigmoid notch in a right angle to the ulnar ridge.

RESULTS

The mean distance of the coronoid process tip to the baseline was 4.0 mm (standard deviation [SD], 1.3 mm; range, 1.4-6.7 mm). The mean distance of the ventral extension of the AMCL to the horizontal line was 3.7 mm (SD, 2.6 mm; range: 9.4-2.2 mm). The mean horizontal distance between the ventral aspect of the AMCL and the coronoid tip was 13.7 mm (SD, 2.5 mm; range, 7.7-20.5 mm).

CONCLUSIONS

We present a detailed description of the insertional anatomy of the AMCL at the sublime tubercle. These values could be helpful for classifications of coronoid fractures and to estimate the involvement of the AMCL in fractures of the sublime tubercle.