The effect of anteromedial facet fractures of the coronoid and lateral collateral ligament injury on elbow stability and kinematics

Pure varus posteromedial rotatory instability of the elbow: Radiographic findings, treatment, and outcomes

INTRODUCTION

Although varus posteromedial rotatory instability (VPMRI) is a subtle elbow injury that involves anteromedial coronoid facet (AMCF) fracture and ligamentous injuries, treatment options and outcomes of VPMRI remains controversial. The aim of this study was to investigate radiographic findings, treatments, and outcomes of a large series of VPMRI.

METHODS

We retrospectively reviewed 91 pure VPMRI cases with AMCF fracture (O'Driscoll classification anteromedial type) which were treated at 6 hospitals. Clinical and radiographic outcomes were investigated with a mean follow-up period of 46.8 months using the Mayo elbow performance score (MEPS), and the Quick Disabilities of the Arm, Shoulder and Hand (Quick-DASH) score, and serial plain radiographs.

RESULTS

In AMCF fracture, there were 4 cases of subtype 1, 67 cases of subtype 2, and 20 cases of subtype 3. On MRI, complete tears of lateral collateral ligament and medial collateral ligament were observed in 83.1 % (59/71 cases) and 33.8 % (24/71 cases). Operative treatment was performed in 68 cases (74.7 %) including both side fixation in 40 cases (58.8 %), medial side fixation only in 17 cases (25.0 %), and lateral side fixation only in 11 cases (16.2 %). Nonoperative treatment was performed in 23 cases (25.3 %). The mean final MEPS and Quick-DASH scores were 93.7 and 7.9. The overall complication and reoperation rates were 22.0 % and 15.4 %. No significant differences regarding final clinical scores and range of motions were observed between the operative group and the nonoperative group, but significant differences were observed regarding number (p = 0.019) and displacement (p = 0.002) of coronoid fragment, and complication rate (p < 0.001) between the two groups.

CONCLUSION

Depending on the pattern of coronoid fragment and the degree of ligamentous injuries, operative treatment of unstable VPMRI using various fixation techniques including coronoid fixation and ligament repair yielded satisfactory final clinical outcomes. However, surgeons should be aware of the high complication and reoperation rates after operative treatment. Stable VPMRI with AMCF fracture involving minimal displacement or small number of fragments can be treated nonoperatively.

Coronoid fractures and complex elbow instability: current concepts

Fractures of the coronoid process typically occur as part of more complex injury patterns, such as terrible triads, trans-olecranon fracture-dislocations, posteromedial rotatory injuries or Monteggia-like lesions. Each pattern is associated with a specific type of coronoid fracture with regard to shape and size and specific soft-tissue lesions. O' Driscoll classification incorporates those associations identifying three major types of fractures: tip, anteromedial facet, and basal fractures. The objective of this study is to review the most common types of complex elbow instability, identify the indications for coronoid fixation and guide the appropriate management. Tip fractures as those seen in terrible triads can conditionally left untreated provided that elbow stability has been restored after radial head fixation and ligaments repair. Anteromedial facet fractures benefit from a buttress plate, while large basilar fractures can be effectively secured with posteroanterior screws. Coronoid reconstruction with a graft should be considered in post-traumatic cases of chronic coronoid deficiency.

A Feasibility Study on Using Hanging Arm Test to Assess Elbow Stability During Surgical Treatment for Varus Posteromedial Rotatory Instability

Objectives

The aim of this study to investigate the safety and effectiveness of performing the hanging arm test during surgical treatment for elbow varus posteromedial rotatory instability (VPMRI) to assess elbow stability and determine whether to repair the lateral ulnar collateral ligament (LUCL).

Methods

In a retrospective study from August 2014 to March 2019, 27 patients with VPMRI who had a negative result in the hanging arm test after fixation of coronoid fracture were selected. Intraoperative bleeding, operative time, elbow range of motion (ROM), and complications were recorded. Elbow function was evaluated with the Mayo elbow performance score (MEPS) and the disabilities of the arm, shoulder, and hand (DASH) score.

Results

The operation time was 85.9 ± 11.06 min (range 65-110). The intraoperative blood loss was 70.7 ± 9.31 ml (range 60-100). At the last follow-up, the elbow joint averaged 73.8° ± 2.931° in pronation, 78.9° ± 2.941° in supination, 7.2° ± 3.207° in extension, and 123.3° ± 6.651° in flexion. The MEPS score was 90.7 ± 4.36 (range 74-95), and the DASH score was 9.8 ± 2.58 (range 6.67-13.3). One patient presented with symptoms of ulnar nerve entrapment 2 months after operation and was treated with ulnar nerve release. The symptom of numbness went away completely 1 week after operation. No complications such as wound infection, arthritis, or chronic instability of the elbow were found in the other patients.

Conclusion

Our findings suggest that not all VPMRI patients need the LUCL to be repaired, and the hanging arm test is a safe and reliable method to assess whether to repair the LUCL in the treatment of elbow VPMRI.

Level of evidence

Level IV; Retrospective studies.

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

BACKGROUND

Coronoid fractures usually occur in the presence of a significant osseoligamentous injury to the elbow. Fracture size and location correlate with degree of instability and many authors have attempted to analyze the effect of fracture variation on decision making and outcome. There remains no standardized technique for measuring coronoid height or fracture size. The aim of this study was to appraise the literature regarding techniques for coronoid height measurement in order to understand variation.

METHODS

Preferred Reporting Items of Systematic Reviews and Meta-Analyses guidelines were followed. A search was performed to identify studies with either a description of coronoid height, fracture size, or bone loss using the terms (Coronoid) AND (Measurement) OR (Size) OR (Height). Articles were shortlisted by screening for topic relevance based on title, abstract and, if required, full-text review. Exclusion criteria were non-English articles, those on nonhuman species or parts other than the ulna coronoid process, and studies that included patients with pre-existing elbow pathology. Shortlisted articles were grouped based on study type, imaging modality, measurement technique, and measurement parameter as well as its location along the coronoid.

RESULTS

Thirty out of the initially identified 494 articles met the inclusion criteria. Twenty-one articles were clinical studies, 8 were cadaveric studies, and 1 combined patients as well as cadavers. A variety of imaging modalities (plain radiographs, 2-dimensional computed tomography [CT], 3-dimensional CT, magnetic resonance imaging or a combination of these) were used with CT scan (either 2-dimensional images or 3-dimensional reconstructions or both) being the most common modality used by 21 studies. Measurement technique also varied from uniplanar linear measurements in 15 studies to multiplanar area and volumetric measurements in 6 studies to techniques describing various angles and indices as an indirect measure of coronoid height in 8 studies. Across the 30 shortlisted studies, 19 different measurement techniques were identified. Fifteen studies measured normal coronoid height while the other 15 measured intact coronoid and/or fracture fragment height. The location of this measurement was also variable between studies with measurements at the apex of the coronoid in 24/30 (80%) of studies. Measurement accuracy was assessed by only 1 study. A total of 12/30 (40%) studies reported on the interobserver and intraobserver reliability of their measurement technique.

CONCLUSION

The systemic review demonstrated considerable variability between studies that report coronoid height or fracture size measurements. This variability makes comparison of coronoid height or fracture measurements and recommendations based on these between studies unreliable. There is need for development of a consistent, easy to use, and reproducible technique for coronoid height and bone loss.

Outcomes and complications after treatment for anteromedial facet fracture of the coronoid process: A systematic review

BACKGROUND

Fracture of the anteromedial facet (AMF) of the coronoid process is associated with varus posteromedial rotatory instability (VPMRI). However, there is still controversy regarding the optimal treatment for AMF fracture. The purpose of this study is to report on a systematic review of the outcomes and complications after treatment for AMF fracture.

METHODS

This study was conducted using electronic databases, PubMed, EMBASE and Scopus. Studies reporting outcome scores and complications were included. Studies that did not utilize O'Driscoll classification for AMF fractures were excluded. Through conduct of a thorough review of included studies, definite VPMRI were identified and cases involving other injury mechanisms were excluded.

RESULTS

Fifteen articles reporting on 246 patients were included. According to O'Driscoll classification, 6.2% of cases were anteromedial subtype I, 73.7% were subtype II, and 20.1% were subtype III. Two-hundred sixteen patients (87.8%) were treated surgically and 30 patients (12.2%) were treated conservatively. Lateral collateral ligament (LCL) injuries were 76.2% (157/206) and medial collateral ligament injuries were 16.9% (33/195). Among 216 cases who underwent surgical treatment, depending on the fragment size, displacement, and instability, coronoid fixation was performed in 189 cases and LCL repair alone was performed in 27 cases. The mean final Mayo Elbow Performance Score was 92.1 and the Broberg & Morrey score was 89.5. The overall complication and reoperation rates were 17.7% (41/232) and 12.9% (26/202).

CONCLUSIONS

Both surgical and conservative treatment for AMF fractures resulted in satisfactory final clinical outcomes. However, high complication and reoperation rates were observed.

Persistent elbow dislocation

Acute elbow dislocation is a common injury with an incidence in the general population estimated at around 5/100,000. Persistent (or static) elbow dislocation is a relatively rare problem but might occur due to inappropriate assessment or treatment of acute simple or complex elbow dislocations. Persistent elbow dislocation can be an invalidating and painful condition with a more ominous prognosis than an acute elbow dislocation with appropriate treatment. Surgical treatment of persistent elbow dislocation is a complex intervention that requires extended surgical exposure and arthrolysis in combination with circumferential ligamentous and osseous stabilization. Satisfactory results are described, but complication and reintervention rates are high. After-treatment with a dynamic external fixator is often necessary.

"How the Wrightington classification of traumatic elbow instability can simplify the algorithm for treatment"

There are numerous injury patterns of elbow-fracture dislocation that can lead to confusion about the best surgical management. The Wrightington classification aims to provide a simple categorization based on the injury to the coronoid process and the three column concept of the elbow osseous stability that describes a medial column consisting of the anteromedial coronoid facet and sublime tubercle, the middlecolumn is the anterolateral coronoid facet, and the lateral column is the radial head and lateral ligament complex with a fulcrum for varus/valgus stability between the two coronoid facets. Injuries are classified as type A (anteromedial facet/medial-column), B (bifacet/ medial and middle-columns), B+ (bifacet with radial head/all three columns), C (combined radial head and anterolateral facet/middle and lateral-columns), D (distal to coronoid where coronoid is in continuity with olecranon process), and D+ (distal to coronoid with radial head fracture). With each bony injury pattern, we can anticipate which soft tissue constraints are likely to be involved and the importance of their repair to restore stability, and thereby develop algorithms for management. The Wrightington classification has been shown to be reliable and valid. A consecutive series of 60 patients with elbow-fracture dislocation managed according to the surgical algorithms of the Wrightington classification have been reported to have excellent outcomes with a median Mayo Elbow Performance Score of 100 (interquartile 85-100) and flexion/extension arc of movement of 123° (interquartile 101°-130°). In conclusion, the Wrightington classification of elbow-fracture dislocation is a comprehensive, reliable, and valid classification with treatment algorithms that are associated with good functional outcomes.

Conservative versus surgical management of isolated O'Driscoll II coronoid fracture: A systematic review

PURPOSE

The purpose of this systematic review is to summarize the current literature on conservative and surgical management of isolated O'Driscoll II coronoid fracture.

STUDY DESIGN

Systematic review.

METHODS

We systematically searched Medline, Embase, Google Scholar, and Web of Science databases for published studies by complying with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and using the keywords "isolated coronoid fracture," "O'Driscoll type 2 coronoid fracture," "anteromedial coronoid fracture," "anteromedial facet coronoid fracture," "posteromedial rotatory instability," and "varus posteromedial rotatory instability." Patients were divided into conservative treatment and surgical treatment groups. Oxford Centre for Evidence-Based Medicine and Methodological Index for Non-Randomized Studies were assessed to determine each article's quality. The primary outcomes of the present reviews were the Mayo elbow performance score (MEPS) and the disabilities of the arm, shoulder, and hand (DASH) score, and the secondary outcomes were associated with complications and reoperations. Eligible trials were independently chosen by two review authors, and a third reviewer resolved all disagreements.

RESULTS

The search yielded 458 records, among which 446 articles were of relevance, and 12 were included. In the final review, 138 patients were evaluated-98 (71%) who received surgical treatment and 40 (29%) who received conservative treatment. The mean MEPS score and the DASH score of surgical treatment were 91 and 8, respectively; 69.8% of patients had excellent scores, and 27.0% had good scores. The mean MEPS score and the DASH score of conservative treatment were 92 and 12, respectively; 70.6% of patients had excellent scores, and 23.5% had good scores.

CONCLUSIONS

In select cases, conservative treatment can achieve good results in the treatment of isolated O'Driscoll II coronoid fracture when a stricter indication is followed. However, there is insufficient evidence to recommend the appropriate treatment for a particular fracture subtype, and there is a need for more high-quality randomized controlled trials to determine which treatment is superior.

Simple lateral elbow dislocation: A case report

BACKGROUND

Simple lateral elbow dislocation (SLED) is a rare type of elbow dislocation; however, its treatment may be complicated by accompanying soft tissue or neurovascular damage. Herein, we report a rare case of SLED managed secon-darily with open reduction and soft tissue repair following failure of closed reduction.

CASE SUMMARY

A 67-year-old woman suffered SLED after falling on her outstretched left hand with her elbow extended. She developed pain, swelling, and movement restriction in the elbow; there were no neurovascular symptoms, except for numbness in the 4^th and 5^th digits. Radiologic investigation confirmed the SLED, and a closed reduction under anesthesia was performed. The follow-up radiographs at 1-wk revealed failure of reduction; accordingly, open reduction with lateral collateral ligament and common extensor origin repair were carried out. The patient regained full elbow range of motion by six weeks.

CONCLUSION

Adequate concentric reduction for SLED, conservatively or surgically, reduces complications and provides a more functional joint.

Improved Understanding of Traumatic Complex Elbow Instability

Recent advancements in surgical treatment have improved clinical results in complex traumatic elbow injury. There is increasing recognition that conservative treatment and inadequate surgical fixation carry high risk of substantial morbidity in many of these cases. Recent literature displays improved outcomes in complex elbow instability, in part, because of a more complete comprehension of the injury patterns and fixation methods. Prompt surgical management with stable internal fixation, which permits immediate postoperative mobilization, has been a consistent variable across the reports leading to more satisfactory outcomes. This applies to both acute and chronic cases.

Anteromedial coronoid facet fractures and associated ligament lesions: A case series

INTRODUCTION

Varus posteromedial rotational injury mechanisms lead to fractures of the coronoids process' anteromedial facet. As these fractures are often unstable, rapid fracture treatment is vital to prevent progressive osteoarthritis.

MATERIALS AND METHODS

Twelve patients with a fracture of the anteromedial facet treated surgically were enrolled in the study. Computed tomography images were used to classify the fractures according to the system by O'Driscoll et al. Clinical follow-up included each patient's medical record, surgical treatment algorithm, all complications encountered during the follow-up period, Disabilities of the arm, shoulder, and hand score, subjective elbow value, and pain.

RESULTS

A total of 8 men (66.7%) and 4 women (33.3%) were treated surgically and followed-up after a mean period of 45 ± 23 months. The mean DASH score was 11.9 ± 12.9 points. One patient complained of transient neuropathy in the innervation area of the ulnar nerve, however, this existed already pre-operatively and resolved after less than three months.

CONCLUSIONS

The presented patient cohort shows that AMF fracture of the coronoid process are unstable lesions according to the bony instability and the frequently ruptured collateral ligament complexes which need to be addressed. The MCL seems to be affected more frequently than previously appreciated.

LEVEL OF EVIDENCE

Level IV; Case Series; Treatment Study.

Morphological Characteristics of Proximal Ulna Fractures: A Proposal for a New Classification and Agreement for Validation

Historically, proximal ulna fractures have been simplistically diagnosed and treated as simple olecranon fractures, leading to an unacceptable number of complications. Our hypothesis was that the recognition of lateral, intermediate, and medial stabilizers of the proximal ulna and ulnohumeral and proximal radioulnar joints would facilitate decision-making, including the choice of approach and type of fixation. The primary aim was to propose a new classification for complex fractures of the proximal ulna based on morphological characteristics seen on three-dimensional computed tomography (3D CT). The secondary aim was to validate the proposed classification regarding its intra- and inter-rater agreement. Three raters with different levels of experience analyzed 39 cases of complex fractures of the proximal ulna using radiographs and 3D CT scans. We presented the proposed classification (divided into four types with subtypes) to the raters. In this classification, the medial column of the ulna involves the sublime tubercle and is where the anterior medial collateral ligament is inserted, the lateral column contains the supinator crest and is where the lateral ulnar collateral ligament is inserted, and the intermediate column involves the coronoid process of the ulna, olecranon, and anterior capsule of the elbow. Intra- and inter-rater agreement was analyzed for two different rounds, and the results were evaluated according to Fleiss kappa, Cohen kappa, and Kendall coefficient. Intra- and inter-rater agreement values were very good (0.82 and 0.77, respectively). Good intra- and inter-rater agreement attested to the stability of the proposed classification among the raters, regardless of the level of experience of each one. The new classification proved to be easy to understand and had very good intra- and inter-rater agreement, regardless of the level of experience of each rater.

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.

Anteromedial coronoid fractures: technical description of an extensile surgical approach and outcomes from a small series using this technique

Background

Varus posteromedial rotatory instability is a difficult clinical problem to diagnose and treat. Fixation of the anteromedial coronoid fracture is often necessary to achieve elbow stability. We describe an extensile surgical approach to the anteromedial coronoid.

Methods

A retrospective review was performed of all patients at our institution who had anteromedial coronoid fracture fixed with this approach between 2012 and 2020.

Results

Six patients were identified. They all achieved a stable elbow. Four of 6 developed heterotopic ossification and 2/6 required further surgery for this. Only 1 patient had a transient ulnar sensory loss.

Conclusion

We describe an approach to the coronoid that allows great visualization of the joint and access to large coronoid fractures. The approach is extensile and does not require extensive dissection or work around the ulnar nerve. Access to fracture and for fixation can be improved by release of the common flexor pronator origin and the medial collateral ligament.

Coronoid fixation and lateral collateral ligament repair in varus posteromedial rotatory instability of the elbow

Background

Varus posteromedial rotatory instability is a relatively rare elbow injury, that has been infrequently reported in published literature. We intended to evaluate the outcomes of surgical management of this rare injury with anteromedial coronoid fixation, and, in selected patients, lateral ulnar collateral ligament (LUCL) repair.

Methods

Between 2017 and 2020, we identified 12 patients with anteromedial coronoid fractures, and a varus posteromedial rotatory instability, who underwent surgery for fixation of the coronoid fracture, with or without LCL repair. All the included patients were either O'Driscoll subtype 2-2, or subtype 2-3. All the 12 patients were followed up for a minimum of 24 months, and their functional outcomes assessed using the Mayo Elbow Performance Score (MEPS).

Results

The mean MEPS recorded in our study was 92.08, and the mean range of elbow flexion achieved was 124.2°. The mean flexion contracture in our patients was 5.83°. Three of our twelve patients (25%) suffered from elbow stiffness even at final follow-up. The results were graded as Excellent in eight, Good in three, and Fair in one patient.

Conclusion

Coronoid fractures and LUCL disruptions associated with varus posteromedial rotatory instability can be reliably managed by employing a protocol that combines radiographic parameters, as well as intra-operative assessments of stability. While surgical intervention successfully restored stability, there is a learning curve to the management of these injuries and complications are not uncommon, particularly elbow stiffness. Hence, in addition to surgical fixation, emphasis should also be placed on intensive post-operative rehabilitation to improve outcomes.

The role of the lateral part of the distal triceps and the anconeus in varus stability of the elbow: a biomechanical study

BACKGROUND

The role of the lateral part of the distal triceps as a stabilizer in the lateral collateral ligament-deficient elbow and whether its effect in improving the stability is independent of that of the anconeus are unclear.

METHODS

Seven cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads while allowing passive flexion of the elbow. An injury model was created by sectioning the lateral collateral ligament and sparing the common extensor origin. The lateral part of the distal triceps tendon was loaded sequentially with 0 N, 10 N, 25 N, and 40 N. Each stage of the lateral part of the distal triceps loading was tested with the anconeus unloaded (inactive) or with a 25-N load applied (active). Articular contact pressures on the coronoid, the medial facet, and the lateral facet were collected and processed using Tekscan sensors and software.

RESULTS

A significant decrease in the mean coronoid contact pressure was seen with sequential loading of the lateral part of the distal triceps (P < .001). The ratio of medial to lateral facet contact pressures significantly decreased with sequential loading of the lateral part of the distal triceps (P < .001), indicating a better distribution of the contact pressure between the medial and lateral facets as the lateral part of the distal triceps was loaded. These effects were statistically significant, both with and without anconeus loading. There was no significant modification of the effect of the lateral part of the distal triceps loading on the contact pressure by the anconeus loading (P = .47). However, with active anconeus loading, the contact pressure and the ratio of medial to lateral facet contact pressures were significantly lower for any stage of lateral triceps loading (P < .001), indicating a synergistic effect of the anconeus.

CONCLUSIONS

In a lateral collateral ligament-deficient elbow, the lateral part of the distal triceps loading prevents the increased contact pressure on the coronoid under varus stress and improves the distribution of contact pressures on the coronoid. Anconeus loading further decreases and improves the distribution of the contact pressures; however, its effect is independent of that of the lateral part of the distal triceps. These results substantiate a role of the lateral part of the distal triceps as a dynamic constraint against elbow varus and have clinical implications for prevention and rehabilitation of elbow instability.

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.

The role of the lateral collateral ligament-capsule complex of the elbow under gravity varus

BACKGROUND

The lateral collateral ligament complex along with the capsule is likely to be at risk during arthroscopic extensor carpi radialis brevis release for lateral epicondylitis. We hypothesized that disruption of the lateral collateral ligament-capsule complex (LCL-cc) would increase the mean contact pressure on the coronoid under gravity varus.

MATERIALS AND METHODS

Eight cadaveric elbows were tested via gravity varus and weighted varus (2 Nm) stress tests using a custom-made machine designed to simulate muscle loads while allowing passive flexion of the elbow. Mean articular surface contact pressure data were collected and processed using intra-articular thin-film sensors and software. Sequential testing was performed on each specimen from stage 0 to stage 3 (stage 0, intact; stage 1, release of anterior one-third of LCL-cc; stage 2; release of anterior two-thirds of LCL-cc; and stage 3, release of entire LCL-cc). The mean contact pressure on the coronoid and the mean ratio of contact pressure on the medial coronoid to that on the lateral coronoid (M/L ratio) were used for comparisons among the stages and the intact elbow.

RESULTS

The overall mean contact pressure significantly increased in stage 2 (P = .0004 in gravity varus and P = .0001 in weighted varus) and stage 3 (P < .0001 in gravity varus and P < .0001 in weighted varus) compared with that in stage 0. In contrast, release of the anterior one-third of the LCL-cc (stage 1) did not significantly increase the mean contact pressure on the coronoid in any degree of flexion under gravity varus (P = .09) or weighted varus loading (P = .6). The M/L ratio difference between stage 0 and stage 1 was 1.1 ± 1.1 under gravity varus (P = .8) and 2.1 ± 1.0 under weighted varus (P = .2). The overall M/L ratios in stage 2 and stage 3 were significantly higher than those seen in stage 0 under gravity varus (P = .04 in stage 2 and P = .02 in stage 3) and weighted varus (P = .006 in stage 2 and P < .0001 in stage 3).

CONCLUSIONS

Loss of the anterior two-thirds or more of the LCL-cc significantly increases the overall mean contact pressure on the coronoid, especially the medial coronoid, under both gravity varus and weighted varus. The LCL-cc also plays a role in the distribution of coronoid contact pressure against gravity varus loads.

Results of arthroscopically assisted reduction and fixation of anteromedial facet coronoid fractures at short-term follow-up

BACKGROUND

Varus posteromedial rotatory instability is a typical pattern of elbow injury that involves fracture of the anteromedial facet (AMF) of the coronoid, as well as injuries to the lateral ligament complex and the posterior bundle of the medial collateral ligament. Some authors support the idea that subtype II AMF coronoid fractures require fixation to restore elbow stability, but this topic is still an issue in the literature. The purpose of this study was to assess the clinical and radiologic outcomes of arthroscopically assisted reduction and internal fixation (ARIF) of AMF fractures.

METHODS

This retrospective single-center trial evaluated consecutive patients who underwent ARIF of isolated subtype II AMF coronoid fractures between 2014 and 2020. At the final follow-up, the patients were examined for elbow range of motion, stability, and pain. Injury and post-treatment radiographs were reviewed to assess fracture healing and heterotopic ossification.

RESULTS

A total of 32 patients (21 male and 11 female patients) with a median age of 47 ± 16 years were included. The average follow-up period was 28 ± 12.4 months. Coronoid process fractures were fixed by cannulated screws in 26 cases (81.25%); in 2 of these cases, additional Kirschner wires were used. Two Kirschner wires were used in 1 case (3.12%), and in the remaining 5 cases (15.62%), osteosuture was used. The lateral ulnar collateral ligament was injured in 27 cases (84.4%) and was always repaired. Other associated lesions were medial collateral ligament injury, osteochondral lesion, and radial head fracture. There were no surgical complications. At the final follow-up, the average Mayo Elbow Performance Score was 98.4 ± 2.7 and the mean Oxford Elbow Score was 47.3 ± 1.4. No cases of nonunion were detected on radiographic assessment.

CONCLUSIONS

Although technically demanding, ARIF has several potential advantages in comparison to open surgery: less scarring, a decreased risk of infection, and less postoperative pain.

Classification of coronoid process fractures: A pending question

Ulna coronoid fracture is a complicated elbow injury. Comprehensive classification of coronoid fracture can assist diagnosis, guide treatment, and improve prognosis. Existing coronoid fracture classifications are insufficient to interpret all fracture patterns. The coronoid fracture classification is associated with elbow-specific trauma patterns. Coronoid fractures are often associated with other elbow injuries, commonly with radial head fractures, which makes the clinical strategies inconsistent and prognosis poor. The current fracture classifications do not contain information about combined injuries. Preservation of ulnohumeral joint contact after trauma is critical to elbow mechanical and kinematic stability. Important fracture types for treatment include terrible-triad injuries and anteromedial facet fractures. Open reduction and internal fixation of these two fractures should be conducted when marked displacement of the fragment, elbow instability under stress, and complicated associated injuries. The current surgical tactics based on classifications are still controversial.

Operative Fixation of the Anteromedial Facet of the Coronoid Process

Anteromedial coronoid facet fractures typically occur with varus, pronation, and axial forces applied to the elbow. Due in part to the high rate of concomitant lateral collateral ligament (LCL) injuries, untreated anteromedial facet fractures can result in varus and posteromedial rotatory elbow instability. Although small fractures that are not amenable to open reduction and internal fixation can be treated with isolated LCL repair, larger fragments are treated with buttress plating on the anteromedial surface of the coronoid with or without LCL repair. The "over-the-top" approach via a split in the flexor pronator mass is the preferred method of accessing the anteromedial facet. Although data regarding the functional outcomes after operative fixation of the anteromedial facet are limited, observational studies have demonstrated good restoration of elbow stability and motion.

Greater sigmoid notch dysplasia causing elbow instability: Lateral ligament reconstruction and Stamp osteotomy

The coronoid is one of the elbow's primary static stabilisers, and the importance of reconstruction following fracture with instability has been established. In the developing elbow, instability can lead to greater sigmoid notch dysplasia that can make reconstruction challenging. A novel technique to improve osseous stability with an opening wedge 'stamp osteotomy' reconstruction of the coronoid is described combined with a lateral ligament reconstruction, in two patients with recurrent posteromedial rotatory instability. The technique improves congruity and coverage of the greater sigmoid notch with the trochlea whilst maintaining articular cartilage. Extra-articular iliac crest bone graft is used to maintain the position with buttress plate support. The surgical technique is described and the clinical and radiographic outcome reported in two patients. Level of evidence: IV.

The use of the internal joint stabiliser for elbow instability Report of two cases and systematic review

The management of elbow fracture-dislocations is challenging. The internal joint stabiliser (IJS) (Skeletal Dynamics, Miami, FL) has been advocated as an alternative to traditional techniques. This article shares our initial clinical experience and provide a systematic review analysing the ability of the IJS to maintain radiographic joint reduction and the associated complication profile. Two cases of elbow fracture-dislocations treated at our centre using the IJS are presented. A systematic review of the literature was conducted using the online databases Medline, Scopus and EMBASE. Clinical studies reporting the maintenance of joint reduction after the use of IJS in patients with acute or chronic elbow instability were included. The two cases reported remained radiographically concentric at 6 months follow up without complications. 5 studies met the inclusion criteria and were included in the systematic review (total n=65). Only two patients across the studies had ongoing radiological instability (3%) and both were associated with coronoid insufficiency. The mean flexion-extension arc ranged from 106° to 135° and pronation- supination arc ranged from 138° to 151°. The mean DASH scores ranged from 16 to 37.3 and the mean Broberg and Morrey Functional score from 68.2 to 93. Complication rates in the case series ranged from 21% to 40%, the commonest complications were heterotopic ossification, neuropathy and infections. Initial reports into the use of the Internal Joint Stabiliser for elbow instability have shown a low incidence of residual radiological joint incongruency.

Coronal Shear Fractures of the Distal Humerus

Coronal shear fractures of the distal humerus are rare, frequently comminuted, and are without consensus for treatment. The aim of this paper is to review the current concepts on the diagnosis, classification, treatment options, surgical approaches, and complications of capitellar and trochlear fractures. Computed Tomography (CT) scans, along with the Dubberley classification, are extremely helpful in the decision-making process. Most of the fractures necessitate open reduction and internal fixation, although elbow arthroplasty is an option for comminuted fractures in the elderly low-demand patient. Stiffness is the most common complication after fixation, although reoperation is infrequent.

[Coronoid reconstruction with autologous iliac crest bone graft in chronic elbow instability through a medial approach]

OBJECTIVE

Neutralizing a posteromedial rotatory instability (PMRI) caused by coronoid deficiency by restoration of the humeroulnar joint surface with an autologous iliac crest bone graft.

INDICATIONS

Surgery is indicated in patients with chronic deficiency of the anteromedial facet of the coronoid with subsequent PMRI.

CONTRAINDICATIONS

Coronoid reconstruction is not recommended in patients with advanced osteoarthritis of the elbow caused by subluxation of the humeroulnar joint. General contraindications like acute infection, pregnancy and lack of operability should also be taken into account.

SURGICAL TECHNIQUE

First, a medial approach is established and the base of the coronoid is prepared. Afterwards an autologous iliac crest bone graft is placed onto the defect and secured by screws or a plate. In addition, a reconstruction of the anterior bundle of the medial collateral ligament with an autologous tendon graft is performed.

POSTOPERATIVE MANAGEMENT

An elbow orthesis is worn for 6 weeks after surgery to avoid valgus or varus stress. There is no restriction in range of motion. A continuous passive motion elbow chair supports the patient in regaining elbow mobility.

RESULTS

Between 2015 and 2017, we treated 10 patients suffering from chronic coronoid defects with coronoid reconstruction. Eight of the patients were available for follow-up 86 weeks after surgery. The mean age was 41.4 years. In all patients, elbow range of motion and patient-related outcome measures were improved after surgery. Plain radiographs illustrated correct centering of the elbow joint. One patient had to undergo elbow arthroplasty and was excluded. Coronoid reconstruction with an autologous iliac crest bone graft restored humeroulnar joint congruency and improved satisfaction in patients suffering from chronic coronoid deficiency.

Repair Versus Non-Repair of Lateral Ulnar Collateral Ligament in Elbow Varus Posteromedial Rotatory Instability Treatment: A Comparative Study

OBJECTIVE

To compare the effects of repairing and not repairing the lateral ulnar collateral ligament (LUCL) when surgically treating elbow varus posteromedial rotatory instability (PMRI).

METHODS

In this retrospective study spanning June 2014 to February 2019, 24 patients with elbow PMRI who were treated surgically were assigned to group RL (Repair LUCL) or group NL (Non-repair LUCL) depending on whether the LUCL was repaired. Hospitalization time, operation time, intraoperative blood loss, and related complications were reviewed. The elbow range of motion (ROM), the visual analog scale (VAS), the Mayo elbow performance score (MEPS), and the disabilities of the arm, shoulder, and hand (DASH) score were used for functional assessment.

RESULTS

Among the 24 patients with PMRI, 15 were assigned to group RL and nine were assigned to group NL. The mean blood loss (184.66 ± 20.3 vs 207.33 ± 19.447, P < 0.001), the operation time (98.88 ± 12.693 min vs 184.66 ± 20.3 min, P < 0.001) were significantly lower in group RL compared to group NL. There were no significant differences between the two groups in time until surgery and follow-up time (6.66 ± 1.838 vs 6.11 ± 1.900 days, 25.53 ± 2.099 vs 26.11 ± 2.891 months, P = 0.577, P = 0.486). All of the patients achieved bone union. The elbow flexion-extension ROM (122.00° ± 3.162°vs 121.11° ± 3.333° at 12 months, P = 0.520) and pronation-supination ROM (154.53° ± 3.335° vs 155.55° ± 4.639° at 12 months, P = 0.537). Both groups achieved similar results in MEPS score (90.53 ± 2.695 vs 89.77 ± 3.865, P = 0.578) and DASH (9.77 ± 1.897 vs 9.99 ± 1.550, P = 0.772) score at the final follow-up. And the MEPS score revealed excellent results (87% in group RL, 89% in group NL).The VAS scores decreased significantly in group RL (from 6.13 ± 0.990 to 1.93 ± 0.593) and group NL (from 5.77 ± 1.481 to 1.88 ± 0.781), and no significant differences in preoperative or final follow-up were observed between the two groups (P = 0.487, P = 0.876). Complications observed in group NL with one patient occurred cubital tunnel syndrome 3 months after the operation, the patient underwent ulnar nerve simple neurolysis and the symptoms were relieved after 3 weeks.

CONCLUSION

For patients with elbow PMRI, satisfactory functional outcomes can be yielded with non-repair of the LUCL as long as the stable elbow joint is performed during operation.

Ultrasonographic Measurement of Elbow Varus Laxity With a Sequential Injury Model of the Lateral Collateral Ligament-Capsular Complex

Background

There is no consensus how to determine the varus laxity due to the LCL injury using the ultrasonography. There is a risk of lateral collateral ligament injury during or after arthroscopic extensor carpi radialis brevis release for tennis elbow. The equator of the radial head has been suggested as a landmark for the safe zone to not increase this risk; however, the safe zone from the intra-articular space has not been established.

Hypothesis

Increased elbow varus laxity due to lateral collateral ligament-capsular complex (LCL-cc) injury could be assessed reliably via ultrasound.

Study Design

Descriptive laboratory study.

Methods

Eight cadaveric elbows were evaluated using a custom-made machine allowing passive elbow flexion under gravity varus stress. The radiocapitellar joint (RCJ) space was measured via ultrasound at 30° and 90° of flexion during 4 stages: intact elbow (stage 0), release of the anterior one-third of the LCL-cc (stage 1), release of the anterior two-thirds (stage 2), and release of the entire LCL-cc (stage 3). Two observers conducted the measurements separately, and the mean RCJ space in the 3 LCL-cc injury models (stages 1-3) at both flexion angles was compared with that of the intact elbow (stage 0). We also compared the measurements at 30° versus 90° of flexion.

Results

At 30° of elbow flexion, the RCJ space increased 2 mm between stages 0 and 2 (95% confidence interval [CI], 1-3 mm; P < .01) and 4 mm between stages 0 and 3 (95% CI, 2-5 mm; P < .01). At 90° of elbow flexion, the RCJ space increased 1 mm between stages 0 and 2 (95% CI, 1-2 mm; P < .01) and 2 mm between stages 0 and 3 (95% CI, 2-3 mm; P < .01).

Conclusion

Elbow varus laxity under gravity stress can be reliably assessed via ultrasound by measuring the RCJ space.

Clinical Relevance

Because ultrasonographic measurement of the RCJ space can distinguish the increasing varus laxity seen with release of two-thirds or more of the LCL-cc, the anterior one-third of the LCL-cc, based on the diameter of the radial head, can be considered the safe zone in arthroscopic extensor carpi radialis brevis release for tennis elbow.

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.

Effect of incremental increase in radial neck height on coronoid and capitellar contact pressures

BACKGROUND

Over-lengthening of the radial neck has been shown to affect ulnohumeral kinematics and has been proposed to affect radiocapitellar pressures. We hypothesized that an incremental increase in radial neck height increases the capitellar contact pressure and reduces the coronoid contact pressure. Knowledge of the effects of over-lengthening is clinically important in preventing pain and degenerative changes due to overstuffing.

METHODS

Six human cadaveric elbows were prepared on a custom-designed apparatus simulating muscle loads and passive flexion from 0° to 90° under gravity valgus torque while measuring joint contact pressures in this biomechanical study. Each elbow was tested sequentially starting with the intact specimen followed by insertion of a radial head prosthesis with 0, +2, and +4 mm of radial neck height, respectively.

RESULTS

Capitellar mean contact pressures significantly increased after insertion of +2 and +4 mm radial head prostheses (p < 0.03). The capitellar mean contact pressure with a 0 mm radial head prosthesis was 97 KPa. Insertion of +2 mm and +4 mm radial heads increased mean contact pressures to 391 KPa (p = 0.001) and 619 KPa (p = 0.001), respectively, with 90° of elbow flexion.

DISCUSSION

Increasing radial prosthesis height by 2 mm significantly increases capitellar contact pressures and reduces coronoid contact pressures.

Current concepts in elbow fracture dislocation

BACKGROUND

Elbow fracture dislocations are complex injuries that can provide a challenge for experienced surgeons. Current classifications fail to provide a comprehensive system that encompasses all of the elements and patterns seen in elbow fracture dislocations.

METHODS

The commonly used elbow fracture dislocation classifications are reviewed and the three-column concept of elbow fracture dislocation is described. This concept is applied to the currently recognised injury patterns and the literature on management algorithms.

RESULTS

Current elbow fracture dislocation classification systems only describe one element of the injury, or only include one pattern of elbow fracture dislocation. A new comprehensive classification system based on the three-column concept of elbow fracture dislocation is presented with a suggested algorithm for managing each injury pattern.

DISCUSSION

The three-column concept may improve understanding of injury patterns and treatment and leads to a comprehensive classification of elbow fracture dislocations with algorithms to guide treatment.

Internal joint stabilizer for varus posteromedial rotatory instability of the elbow

BACKGROUND

Management of varus posteromedial rotatory instability (VPMRI) of the elbow presents a challenging problem, sometimes requiring supplemental external fixation or ulnohumeral cross-pinning. A relatively new treatment adjunct for posterolateral rotatory instability of the elbow has become available with the development of the internal joint stabilizer (IJS) implant. However, this has not been studied for VPMRI because the implant is thought to be ineffective at treating this instability when placed in the usual manner on the lateral side of the elbow. We hypothesize that modifying the IJS technique to place the implant medially will make it as effective as external fixation at preventing VPMRI.

METHODS

Nine whole-arm cadaveric specimens were tested on a rig that allowed for gravity stress of the elbow at 60° of abduction. Intact specimens (INT) were tested to find the baseline stability with all structures intact. Then, O'Driscoll type 2-subtype III coronoid fractures were created with a microsagittal saw, and these same specimens were again tested without any fixation (WAF), with a static lateral external fixator (SLEF), and with a medially placed IJS (MIJS). The method for medial IJS placement is detailed within.

RESULTS

The WAF specimens were significantly more unstable than the INT, SLEF, and MIJS groups (P < .001). There was no difference in stability between the INT and the SLEF (P = .59) or MIJS group (P = .21).

CONCLUSION

In this cadaveric model, a medially placed IJS was as effective as an SLEF at maintaining elbow stability in a coronoid-deficient elbow. This technique allows for early elbow range of motion, with no external hardware, and may eliminate the complications associated with external fixation or ulnohumeral cross-pinning.

Clinical comparison of the over-the-top and flexor carpi ulnaris split approaches for the treatment of anteromedial facet fracture of the coronoid process

BACKGROUND

The flexor carpi ulnaris (FCU)-split approach and the over-the-top approach have been used frequently for the fixation of anteromedial facet (AMF) fractures of the coronoid process. Clinical studies have not compared functional recovery and complication rates associated with these approaches. This study aimed to compare the clinical effectiveness of the over-the-top and FCU-split approaches for the treatment of AMF fractures of the coronoid process.

METHODS

Thirty-two patients who underwent surgery for AMF fractures between January 2013 and August 2019 were divided into the FCU-split and over-the-top groups. The FCU-split approach was used from January 2013 to March 2016, and the over-the-top approach was used from April 2016 to August 2019. Bony union, radiographic signs of osteoarthritis (Broberg and Morrey classification), and development of heterotopic ossification were evaluated. Postoperative pain score (visual analog scale at 2 days after the operation), surgical time (minutes), range of motion of the elbow, elbow function (Mayo Elbow Performance Score [MEPS]), and the presence of postoperative ulnar neuropathy were also compared between the 2 groups.

RESULTS

The FCU-split and over-the-top approaches were performed in 15 and 17 patients, respectively. The mean age was 46 ± 13 years (range, 22-67 years), and the mean follow-up duration was 19± 6.7 months (range, 13-38 months). All coronoid fractures had a solid osseous union during the follow-up, and no subluxation or dislocation was observed in the 2 groups. The occurrence of heterotopic ossification and the grade of post-traumatic arthritis did not differ significantly between the groups (all P > .05). There were also no significant differences between the groups in terms of postoperative pain score, range of motion, and MEPS (all P > .05). However, the surgical time was shorter for the over-the-top approach than that for the FCU-split approach (79± 23 vs. 101 ± 14, P = .008), and the surgical time was significantly associated with the fracture classification and surgical approach (P = .001 and .003, respectively). In addition, postoperative ulnar neuropathy occurred less with the over-the-top approach than with the FCU-spilt approach (5.9% vs. 46%, P = .013).

CONCLUSION

Both the FCU-split and over-the-top approaches were appropriate for performing the buttress plate fixation for AMF fractures of the coronoid process and for restoring the elbow stability. The fixation of AMF fractures through the over-the-top approach was technically easier and had less incidence of postoperative ulnar neuropathy.

Morphological characteristics of fractures of the anteromedial facet of the coronoid in posteromedial rotatory instability of the elbow: a three-dimensional CT remodeling study

BACKGROUND

Fractures of the anteromedial facet of the coronoid in posteromedial rotatory instability of the elbow are classified into 3 subtypes based on their location. The purpose of this study was to analyze the fracture morphology of anteromedial facet fractures in their 3 subtypes (anteromedial rim, anteromedial rim + tip, and anteromedial rim + sublime tubercle [±tip]).

METHODS

Three-dimensional computed tomography remodeling was used to evaluate anteromedial facet fractures in a consecutive series of 40 patients, all of whom were affected by posteromedial rotatory instability of the elbow. Characteristics of the fractures, including the number of fragments, size of fragments, plane of the fracture line, and involvement of the sublime tubercle and radial notch, were measured for each subtype of the anteromedial facet fractures.

RESULTS

Each subtype had a typical fracture pattern and distinct size. The fracture subtype 1 showed a single-fragment fracture, subtype 2 showed either a single- or dual-fragment fracture, and subtype 3 showed either a dual- or triple-fragment fracture. The angle between the fracture line and the coronal plane was greatest in subtype 3 fractures. The surface area of the fragment was largest in subtype 3 fractures. The percentages of articular involvement of the sublime tubercle were 0% in subtype 1, 47% in subtype 2, and 79% in subtype 3. The percentages of articular involvement of the radial notch were 0% in subtype 1, 7% in subtype 2, and 8% in subtype 3.

CONCLUSION

Analysis with quantitative 3-dimensional computed tomography showed the characteristic morphology of each subtype of anteromedial facet fracture. Subtype 1 comprised 1 fragment with the smallest fragment size. Subtype 2 was a single- or dual-fragment fracture, the size of which should be considered in the treatment plan. Subtype 3 was a large fragment comprising the sublime tubercle. Our findings are significant because they highlight unique fracture morphology that may help surgeons to distinguish one fracture subtype from another in clinical practice.

Coronoid process reconstruction with a distal clavicle autograft: an in silico analysis of fitting accuracy

BACKGROUND

The coronoid process plays a vital role in preserving elbow stability. In cases of acute or chronic deficiency of the coronoid process, reconstruction is warranted to restore stability and to avoid early joint degeneration. The distal clavicle might be a useful osteochondral autograft for coronoid reconstruction with low donor-site morbidity. This study evaluated the fitting accuracy of the distal clavicle as an autograft for coronoid process reconstruction.

METHODS

One hundred upper-extremity computed tomography scans of 85 body donors were available for this study (mean age, 69 ± 17 years; 46 male and 39 female donors; 15 bilateral specimens). Standardized 40% transverse defects of the coronoid process were digitally created; the distal clavicles were digitally harvested and placed onto the defects by a best-fit technique in 2 different orientations using commercially available software: (1) with the superior aspect of the articular surface of the graft oriented toward the coronoid tip and (2) with the inferior aspect of the articular surface of the graft oriented toward the coronoid tip. The fitting accuracy of the grafts to the native coronoid process was evaluated from lateral to medial using custom code.

RESULTS

Regardless of the orientation of the graft, the distal clavicle provided a good fit in the central portion of the coronoid process. In the lateral and medial aspects of the defect, however, the fitting accuracy of the graft declined significantly (P ≤ .044). No significant differences were observed between ipsilateral and contralateral grafts (P ≥ .199). The intrarater reliability was excellent.

CONCLUSION

The results of this study suggest that a distal clavicle autograft may be suitable to replace a transverse defect of the coronoid process; however, it may not fully reconstruct the anteromedial and anterolateral aspects of the coronoid.

Management of anteromedial coronoid fractures according to a protocol focused on instability assessment provides good outcomes with infrequent need for coronoid fixation

BACKGROUND

Anteromedial coronoid fractures (AMCFs) are associated with persistent elbow instability and post-traumatic arthritis if managed incorrectly. It is unclear exactly which AMCFs require surgical intervention and how to make this decision. The aims of this study were to report outcomes of AMCFs managed using a protocol based on reproduction of instability using radiographic and clinical testing and to ascertain a threshold size of AMCF associated with instability.

METHODS

Forty-three AMCFs were studied. Thirty-two patients formed the primary study group (group A). All were treated using a protocol in which the decision to perform coronoid fixation was based on the presence of radiographic or clinical evidence of instability. Functional outcomes (Oxford Elbow Score), radiographic outcomes, complications, and reoperations were collected, and a receiver operating characteristic curve analysis was performed to assess the optimal coronoid fracture height to recommend coronoid fixation. The results were compared with a historical group of 11 patients with AMCFs not treated according to the protocol (group B).

RESULTS

Of the patients, 23 had an isolated AMCF and 20 had a concurrent radial head injury. Complete nonoperative treatment of the elbow was performed in 16 patients (37%) (11 of 32 [34%] in group A vs. 5 of 11 [45%] in group B, P = .46). In 10 patients (23%), only repair of the lateral collateral ligament was performed (9 in group A and 1 in group B), whereas 8 patients (19%) underwent repair of the lateral collateral ligament and radial head fixation or replacement (6 in group A and 2 in group B). Acute coronoid fixation was performed in 9 patients (21%) (6 in group A and 3 in group B). At a mean follow-up of 20 months (range, 12-56 months), group A showed a significantly better Oxford Elbow Score (42 vs. 31, P = .02), lower complication rate (3 of 32 [9%] vs. 8 of 11 [72%], P < .001), and lower reoperation rate (1 of 32 [3%] vs. 6 of 11 [54%], P < .001) than group B. Persistent instability was found in 6 patients in group B and none in group A. The receiver operating characteristic curve analysis demonstrated 6.5 mm to be the optimal AMCF size for surgery to prevent persistent instability.

CONCLUSION

Patients treated according to a protocol in which preoperative reproduction of instability determined the degree of surgical intervention had good clinical and radiographic outcomes. Our study demonstrated that AMCFs > 6.5 mm are likely to be more unstable and require intervention. If these principles are followed, a specifically defined subset of AMCFs can be treated nonsurgically without adverse outcomes.

The treatment of anteromedial coronoid facet fractures: a systematic review

BACKGROUND

Fractures of the anteromedial facet (AMF) of the coronoid process are caused by a varus posteromedial rotational injury force, leading to instability in the ulnohumeral joint. AMF fractures are usually accompanied by avulsion of the lateral ulnar collateral ligament (LUCL). O'Driscoll's description and classification of AMF coronoid fractures has increased awareness and interest in this injury, but the optimal treatment has yet to be decided.

METHODS

We systematically reviewed the available literature searching electronic databases, MEDLINE using the PubMed interface and Embase. The primary objective was to determine outcome scores but also complication and revision rates depending on the fracture and its therapy in order to gain a more comprehensive picture. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were applied.

RESULTS

Initially, 304 publications were identified. Finally, 10 studies were left for inclusion, all of them retrospective in design, comprising 128 patients; the majority of them were male (75.7%). A total of 114 patients (89.1%) were treated surgically and 14 patients (10.9%) were treated conservatively. Among the surgically treated patients, 70.2% were treated with LUCL refixation. The average Mayo Elbow Performance Score of the surgically treated patients was 91.5 points. The average Mayo Elbow Performance Score of the conservatively treated patients was 91.4 points. A total of 10 patients (7.8%) required reoperation.

CONCLUSION

Surgery of AMF fractures leads to a satisfactory functional outcome in the vast majority of patients independent of the subtype. An algorithm for LUCL fixation is still pending. Conservative treatment may be considered under strict preconditions, especially for nondisplaced subtype 1 and 2 fractures, as these fractures show satisfactory functional outcomes when treated nonoperatively.

Results of standardized treatment of elbow fracture dislocations as per their injury pattern: a retrospective cohort of 89 patients

Background

Elbow fracture dislocations represent difficult injuries to treat, with a high percentage of complications. Classically, they are divided into posterolateral, posteromedial and transulnar pattern. It is essential to distinguish them to guide intraoperative treatment to achieve an anatomic and stable reduction that allows early mobility.

Methods

A retrospective study of 89 adult patients diagnosed with elbow fracture dislocations who underwent a standardized surgery between 2013 and 2018 with a minimum follow-up of 12 months. Demographic data, characteristics of the injury, and associated procedures were collected. Patients were evaluated with functional scores (Mayo elbow performance score/Broberg and Morrey score) and ranges of movement at the end of the follow-up.

Results

The mean age was 41 ± 12 years, mostly men (82%), with an average follow-up of 29 months. We present 42 patients with posterolateral fracture dislocation (47%), 21 posteromedial (24%) and 26 transulnar (29%). The average range of motion at the end of follow-up was −12 ± 11° extension, 124 ± 20° flexion, 76 ± 16° pronation, and 73 ± 20° supination, with a Mayo elbow performance score of 88.7 ± 12 points and 87.2 ± 12 points in the Broberg and Morrey scale. Reoperation rate was 23%, with no infection or heterotopic ossification cases. Transulnar fracture dislocations have significantly worse extension and supination. As per the functional result (Mayo elbow performance score/Broberg and Morrey scale), there are no significant differences between the different patterns.

Conclusion

Proper injury pattern recognition and a standardized surgical management lead to a stable joint and good results in range of motion. Functional results are encouraging at least at short term, despite the high reoperations rate.

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.

Magnetic resonance imaging of the elbow

Elbow pain can cause disability, especially in athletes, and is a common clinical complaint for both the general practitioner and the orthopaedic surgeon. Magnetic resonance imaging (MRI) is an excellent tool for the evaluation of joint pathology due to its high sensitivity as a result of high contrast resolution for soft tissues. This article aims to describe the normal imaging anatomy and biomechanics of the elbow, the most commonly used MRI protocols and techniques, and common MRI findings related to tendinopathy, ligamentous and osteochondral injuries, and instability of the elbow.

Novel exploration of 3D printed personalized total elbow arthroplasty to solve the severe bone defect after internal fixation failure of comminuted distal humerus fracture: A case report

RATIONALE

Severe bone defect could often occur after removing the fractured fixation plates of comminuted fracture in the distal humerus. The reoperation of internal fixation or conventional total elbow arthroplasty could hardly restore the anatomy structure and function of the elbow. However, a novel exploration of 3-dimensional (3D) printed personalized elbow prosthesis was presented in this work. This is a rare and successful treatment for the severe bone defect after removing the fractured fixation plates of comminuted distal humerus fracture.

PATIENT CONCERNS

A 60-year-old male patient was admitted to the hospital with the chief complaint of right elbow joint pain and limitation of motion for 10 years. He suffered from an open reduction with internal fixation surgery 10 years ago due to a fall injury-induced right distal humerus fracture.

DIAGNOSES

Plain radiographs and computed tomography scan revealed fracture lines, fracture displacement, and fixator breakage in the right distal humerus. Pain, swelling, and limitation of motion could be found in the physical examination. Fixation failure and nonunion after internal fixation of comminuted distal humerus fracture were considered.

INTERVENTIONS

The patient was treated with 3D printed personalized TEA and functional rehabilitation exercises.

OUTCOMES

No severe complications were observed during the 36 months follow-up. The patient could complete the daily activities without pain. The hospital for special surgery score increased from 15 points before surgery to 90 points 36 months after surgery.

LESSONS

The 3D printed personalized prosthesis could successfully reconstruct the anatomical structures and function of the elbow joint with a severe bone defect. The 3D printed personalized total elbow arthroplasty might provide a feasible method for treating the complex elbow joint diseases in the elderly.

[Treatment of ulnar coronoid process fracture via a modified anteromedial approach]

OBJECTIVE

To investigate the effectiveness of a modified anteromedial approach in the treatment of ulnar coronoid process fracture.

METHODS

Between February 2017 and July 2018, 15 patients with ulna coronoid process fracture were reviewed. There were 9 males and 6 females, with an average age of 42.3 years (range, 24-60 years). The causes of injury included falling in 10 cases and traffic accidents in 5 cases, all cases were closed injury. According to the O'Driscoll classification, there were 4 cases of type Ⅰ, 6 cases of type Ⅱ, and 5 cases of type Ⅲ. The time from injury to operation was 2-8 days (mean, 3.7 days). All fractures were treated via a modified anteromedial approach between the pronator teres and the flexor carpi radialis plus with partial incision of flexor tendon aponeurosis. The fracture healing, muscle strength of forearm, postoperative complications were observed. At last follow-up, the elbow mobility were measured, the function of elbow was evaluated by Mayo elbow performance score (MEPS).

RESULTS

All cases were followed up 10-18 months (mean, 13.3 months). Fracture union was achieved in all patients with a mean time of 10 weeks (range, 8-14 weeks). No obvious decrease of hand grip strength, nerve injury, and infection occurred. One patient had slight heterotopic ossification without special treatment. At last follow-up, all patients had stable elbows with good flexion-extension and varus-valgus stability, the mean flexion was 123.3° (range, 100°-140°), mean extension loss compared with that before operation was 6.7° (range, 0°-20°), mean pronation was 76.0° (range, 60°-85°), and mean supination was 75.8° (range, 55°-90°). The MEPS score was 65-100 (mean, 90.3) with the result of excellent in 10 cases, good in 4 cases, and fair in 1 case.

CONCLUSION

The treatment of ulnar coronoid process fracture via the modified anteromedial approach provides excellent exposure, minimal invasion, fewer complications, and satisfactory prognosis, which is conducive to elbow joint function recovery.

Buttress plate fixation of coronoid process fractures via a medial approach

PURPOSE

To assess the clinical and radiographic outcomes of coronoid process fractures surgically managed with buttress plate fixation via a medial approach.

METHODS

A retrospective review of all coronoid fractures surgically fixed in our institution using a buttress plate technique via a medial approach between June 2012 and April 2015 by the senior author was performed. These fractures were all sizeable fractures contributing to persistent elbow instability in terrible triad or varus posteromedial rotatory instability injury patterns. A prospective telephone questionnaire was conducted to assess patient outcomes using the disabilities of the arm, shoulder and hand (DASH) score and Mayo hlbow performance score (MEPS).

RESULTS

Twelve patients were included in the study, comprising 10 males and 2 females with an average age of 39 years (range, 19-72 years). Mean follow-up was 16 months (range, 4-18 months). The average time to radiographic union was 4 months (range, 3-7 months). Range of motion measurements at final follow-up were obtained in 11 out of 12 patients, with one patient defaulting follow-up. All 11 patients displayed a functional elbow range of motion of at least 30°-130°, with an average arc of motion of 130° (range, 110° -140°), mean elbow flexion of 134° (range, 110° -140°) and mean flexion contracture of 3° (range, 0° -20°). The mean DASH score was 16 (range, 2.5-43.8) and the mean MEPS was 75 (range, 65-100). Complications observed included one patient with a superficial wound infection which resolved with a course of oral antibiotics and one patient with radiographic evidence of heterotopic ossification which was conservatively managed. No residual elbow instability was observed and no reoperations were performed.

CONCLUSION

Buttress plate fixation via a medial approach of coronoid process fractures that contribute to persistent elbow instability represents a reliable method of treatment that produces satisfactory and predictable outcomes.

Arthroscopically-assisted fixation of anteromedial coronoid facet fracture and lateral ulnar collateral ligament repair for acute posteromedial rotatory fracture dislocation of the elbow

If left untreated, varus posteromedial rotatory injuries of the elbow result in poor functional outcomes. Surgical treatment allows restoration of elbow kinematics, minimizing the chances of chronic varus instability and early onset osteoarthritis. However, large exposures are associated with extensive soft tissue stripping, a high risk of infection, nerve injury, poor visualization of the articular surface and longer recovery. Consequently, there has been renewed interest in the use of elbow arthroscopy to circumvent these problems. Arthroscopic treatment offers the potential advantage of a swift recovery, with instant rehabilitation, less stiffness and swelling than might be expected after open repair. We present the first combined arthroscopic-assisted anteromedial facet coronoid fracture fixation and lateral ulna collateral ligament repair in a varus posteromedial rotatory injury of the elbow.

Isolated complete ulnar collateral ligament tear of the elbow in a gymnast: does it need surgery?

Ulnar collateral ligament (UCL) tears can occur from trauma or chronic overuse, and the treatment depends on the type of sport the patient plays and the severity of symptoms. Overuse UCL injuries are most commonly due to micro-trauma in overhead athletes such as baseball players, softball players, and tennis players. Acute complete UCL tears in athletes due to trauma are less common but generally operative treatment is recommended. In gymnastics, elbow dislocations are more common than isolated UCL injuries, and there is sparse literature on the success of non-operative treatment of isolated UCL injuries in this group of athletes. In this case report, we report a high-level competitive gymnast with an UCL tear and a partial tear of the forearm flexor mass, which was confirmed by a thorough careful physical examination and magnetic resonance imaging. The patient was treated non-operatively and successfully returned to gymnastics without symptoms. This case supports the suggestion that UCL tears of the elbow can be treated successfully in some gymnasts without surgery, and that treatment should be individualized in this group of athletes.

Most coronoid fractures and fracture-dislocations with no radial head involvement can be treated nonsurgically with elbow immobilization

HYPOTHESIS

Conservative treatment of isolated coronoid fractures and fracture-dislocations focused on soft-tissue healing can provide good clinical results in the majority of patients. Our aims were (1) to evaluate the outcome of a conservative treatment protocol designed for isolated coronoid fractures with or without associated elbow dislocations (ICFs) and (2) to characterize the fractures with a dedicated image analysis protocol.

METHODS

Of 38 consecutive patients sustaining acute ICFs, 28 were treated nonsurgically after meeting specific inclusion criteria, prospectively followed up, and clinically evaluated at least 1 year after sustaining their injuries. All cases underwent elbow computed tomography scans with tri-plane and 3-dimensional reconstructions according to a specific protocol referenced to the proximal ulna.

RESULTS

The study included 15 male and 13 female patients, with a mean follow-up period of 32 ± 14 months (range, 12-61 months). An associated dislocation was presented in 8 (29%). Mean extension and flexion were 2° ± 8° (range, -10° to 30°) and 139° ± 11° (range, 110°-155°), respectively. Mean pronation and supination were 74° ± 3° (range, 60°-75°) and 83° ± 9° (range, 40°-85°), respectively. Of the patients, 78% rated their elbow as being normal or nearly normal. The mean Mayo Elbow Performance Score was 95 ± 9 (range, 70-100). The mean Disabilities of the Arm, Shoulder and Hand score was 7 ± 13 (range, 0-57). The mean coronoid fracture height was 5.7 ± 1.2 mm (range, 3.7-7.9 mm). The mean percentage of coronoid height fractured was 33% ± 6% (range, 23%-43%). Mean fracture displacement was 2.7 ± 2 mm (range, 1-9 mm). Of the fractures, 23 (82%) were located at the anteromedial coronoid.

CONCLUSION

An ICF with a perfectly reduced ulnohumeral joint, a competent sublime tubercle, and a fractured coronoid height up to 50% can be treated without surgery with excellent or good results in more than 90% of cases regardless of the location of the fracture in the coronoid or the type of soft tissue-associated disruptions.

The shape match of the olecranon tip for reconstruction of the coronoid process: influence of side and osteotomy angle

BACKGROUND

The integrity of the coronoid process is critical to maintaining elbow stability. Unreconstructible fractures and chronic coronoid deficiency are challenging clinical problems with no clear solution. The purposes of this study were to investigate the shape match of the ipsilateral and contralateral olecranon tips as graft options and to determine the influence of the osteotomy angle on fitment.

METHODS

Nineteen paired cadaveric elbow joints were investigated by 3-dimensional digital analysis of computed tomography DICOM (Digital Imaging and Communications in Medicine) data. After construction of an ulnar coordinate system, the ipsilateral and contralateral olecranon tips were digitally harvested at 10°, 20°, 30°, 40°, 50°, and 60° osteotomy angles. In an overlay analysis, we compared the shape match of the ipsilateral and contralateral grafts and the different angles.

RESULTS

The ipsilateral grafts showed an average mismatch of 1.8 mm (standard deviation, 1.38 mm), whereas the contralateral grafts had a significantly lower (P < .001) mean mismatch of 1.3 mm (standard deviation, 0.95 mm). The 50° osteotomy plane showed the best shape match in comparison with the native coronoid-in both the ipsilateral and contralateral grafts. Evaluation of the intraclass correlation coefficient was calculated at r = 0.944, showing high repeatability of the measurements.

CONCLUSIONS

The contralateral olecranon tip graft showed significantly better shape matching to the native coronoid than the ipsilateral olecranon graft. Specifically, the contralateral graft more closely matched the biomechanically critical anteromedial coronoid facet. Finally, both the contralateral and ipsilateral olecranon grafts had better shape matching with the native coronoid when osteotomy was performed at higher angles, specifically 50°.

Independent Locking Screws for Articular Fragment Fixation in the Elbow

Articular fractures of the elbow require direct reduction and interfragmentary fixation to restore anatomic stability. The fragments are often small, with limited bone stock, hence implants are often placed through the articular surface to gain maximal purchase. Traditional techniques involve the use of countersunk cortical screws or cannulated headless compression screws. We describe a technique in which small locking screws are used independently from a plate as a substitute for headless or other traditional screws. This method of fixation negates the need for countersinking the screw head, or over drilling a guide wire, and enables the use of smaller diameter screws which provide excellent purchase in very small fragments. Independent locking screws can be considered for any fracture that previously would have been amenable to cortical or headless compression screw fixation. Locking screws from several manufacturers have been used with equal success. Screws can be used in a unicortical manner if necessary, as the grip comes from engaging the subchondral bone with the locking thread. This technique has been used on 35 consecutive articular elbow fractures with a minimum 6-month follow-up. All fractures have achieved bony union within this period, and there have been no loss of fixations or requirement for further surgeries to remove prominent metalwork.

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.