Variations in the normal anatomy of the collateral ligaments of the human elbow joint

The lateral ulnar collateral ligament: Anatomical and structural study for clinical application in the diagnosis and treatment of elbow lateral ligament injuries

The lateral ulnar collateral ligament (LUCL) is considered one of the main stabilizers of the elbow. However, its anatomical description is not well established. Imaging techniques do not always have agreed upon parameters for the study of this ligament. Therefore, herein, we studied the macro and microanatomy of the LUCL to establish its morphological and morphometric characteristics more precisely. Fifty-five fresh-frozen human elbows underwent dissection of the lateral collateral ligament. Morphological characteristics were studied in detail. Ultrasound (US) and magnetic resonance (MR) were done before dissection. Two specimens were selected for PGP 9.5 S immunohistochemistry. Ten additional elbows were analyzed by E12 sheet plastination. LUCL was identified in all specimens and clearly defined by E12 semi-thin sections. It fused with the common extensor tendon and the radial ligament. The total length of the LUCL was 48.50 mm at 90°, 46.76 mm at maximum flexion and 44.10 mm at complete extension. Three morphological insertion variants were identified. Both US and MR identified the LUCL in all cases. It was hypoechoic in the middle and distal third in 85%. The LUCL was hypointense on MR in 95%. Free nerve endings were present on histology. The LUCL is closely related to the anular ligament. It is stretched during flexion and supination. US and MR can reliably identify its fibers. Anatomical data are relevant to the surgeon who repairs the ligaments of the elbow. Also, to the radiologist and pain physician who interpret imaging and treat patients with pain syndromes of the elbow.

Imaging of Anatomical Variants Around the Elbow

The elbow is a synovial joint able to perform flexion, extension, supination, and pronation. Knowledge of anatomical variants is crucial to avoid misinterpretation during the evaluation of the elbow joint. We address those anatomical variants simulating pathologic conditions.

Lateral Ulnar Collateral Ligament of the Elbow Joint: Reconsideration of Anatomy in Terms of Connection with Surrounding Fibrous Structures

BACKGROUND

To improve the clinical results of lateral ulnar collateral ligament (LUCL) reconstruction of the elbow joint, better understanding of the anatomy of the aponeuroses and joint capsule could be relevant. This study considers the previously described anatomy of the LUCL in relation to the related aponeuroses and joint capsule rather than as a discrete ligament. We hypothesized that the deep aponeuroses of the superficial extensor muscles and supinator form a relevant portion of the joint capsule previously defined as the LUCL.

METHODS

Twenty-four elbows (12 right) from 21 embalmed cadavers (age at the time of death, 54 to 99 years) were included in the study. Twenty elbows were studied macroscopically and 4, histologically. The joint capsule was detached from the bones, and local thickness was quantitatively analyzed using micro-computed tomography (micro-CT).

RESULTS

The supinator aponeurosis and joint capsule intermingled to form a thick membrane (mean and standard deviation, 4.8 ± 1.2 mm), which we termed "the capsulo-aponeurotic membrane." It was thicker than the anterior (1.3 ± 0.4 mm) and posterior (2.5 ± 0.9 mm) parts of the capsule of the humeroradial joint (p < 0.001). The capsulo-aponeurotic membrane had a wide attachment on the distal part of the extensor digitorum communis and extensor digiti minimi (EDC/EDM) origin of the humerus, the lateral part of the coronoid process, and the posterior part of the radial notch of the ulna. The humeral attachment had a fibrocartilaginous structure. The deep aponeuroses of the EDC and extensor carpi ulnaris (ECU) were connected to the capsulo-aponeurotic membrane.

CONCLUSIONS

The capsulo-aponeurotic membrane was composed of the supinator aponeurosis and joint capsule and was attached to the lateral epicondyle of the humerus, radial side of the coronoid process, and posterior part of the radial notch on the ulna. The entire structure appeared identical to the commonly defined lateral collateral ligament. The most posterior part was connected to the EDC and ECU aponeuroses, which is commonly labeled the LUCL but does not exist as a discrete ligament.

CLINICAL RELEVANCE

Consideration of the accurate anatomy of the extensive attachment of the capsulo-aponeurotic membrane could provide useful clues for improvement in techniques of LUCL reconstruction and lateral epicondylitis pathology.

Elbow valgus stability of the transverse bundle of the ulnar collateral ligament

Background

The purpose of this study was to clarify elbow valgus stability of the transverse bundle (TB). We hypothesized that the transverse bundle is involved in elbow valgus stability.

Methods

Twelve elbows of six Japanese Thiel-embalmed cadavers were evaluated. The skin, subcutaneous tissue and origin of forearm flexors were removed from about 5 cm proximal to the elbow to about 5 cm distal to the elbow, and the ulnar collateral ligament was dissected (intact state). The cut state was defined as the state when the TB was cut in the middle. The joint space of the humeroulnar joint (JS) was measured in the intact state and then in the cut state. With the elbow flexed to 30°, elbow valgus stress was gradually increased to 30, 60 N using the Telos Stress Device, and the JS was measured by ultrasonography under each load condition. Paired t-testing was performed to compare the JS between the intact and cut states under each load.

Results

No significant difference in JS was identified between the intact and cut state at start limb position. The JS was significantly higher in the cut state than in the intact state at both 30 N and 60 N.

Conclusion

The findings from this study suggested that the TB may be involved in elbow valgus stability.

Role of the transverse ligament of the ulnar collateral ligament of the elbow: a biomechanical study

Background

The ulnar collateral ligament (UCL) complex of the elbow plays a primary role in valgus and posteromedial stability of the elbow. The anterior oblique ligament (AOL) of the UCL is believed to provide the majority of resistance to external forces on the medial elbow. The transverse ligament (TL) of the UCL is generally thought to have minimal contribution to the elbow’s overall stability. However, recent studies have suggested a more significant role for the TL. The primary aim of this study was to identify the TL’s contribution to the stability of the elbow joint in determining the joint stiffness and neutral zone variation in internal rotation.

Methods

Twelve cadaveric elbows, set at a 90° flexion angle, were tested by applying an internal rotational force on the humerus to generate a medial opening torque at the level of the elbow. The specimens were preconditioned with 10 cycles of humeral internal rotation with sinusoidal torque ranging from 0 to 5 Nm. Elbow stiffness measures and joint neutral zone were first evaluated in its integrity during a final ramp loading. The test was subsequently repeated after cutting the TL at 33%, 66%, and 100% followed by the AOL in the same fashion.

Results

The native UCL complex joint stiffness to internal rotation measured 1.52 ± 0.51 Nm/°. The first observable change occurred with 33% sectioning of the AOL, with further sectioning of the AOL minimizing the joint stiffness to 1.26 ± 0.32 Nm/° (P = .004). A 33% resection of the TL found an initial neutral zone variation of 0.376 ± 0.23° that increased to 0.771 ± 0.41° (P < .01) at full resection. These values were marginal when compared with the full resection of the AOL for which we have found 3.69 ± 1.65° (P < .01).

Conclusion

The TL had no contribution to internal rotation elbow joint stiffness at a flexion angle of 90°. However, sequential sectioning of the TL was found to significantly increase the joint neutral zone when compared with the native cadaveric elbow at a flexion angle of 90°. This provides evidence toward the TL having some form of contribution to the elbow’s overall stability.

Quantitative and Qualitative Analyses of the Lateral Ligamentous Complex and Extensor Tendon Origins of the Elbow: An Anatomic Study

Background:

The lateral collateral ligament complex of the elbow is important in preventing posterolateral rotary instability of the elbow. Understanding the quantitative anatomy of this ligamentous complex and the overlying extensor musculature can aid in the surgical treatment of problems affecting the lateral side of the elbow.

Purpose:

To perform qualitative and quantitative anatomic evaluations of the lateral elbow ligamentous complex and common extensor muscle origins with specific attention to pertinent osseous landmarks.

Study Design:

Descriptive laboratory study.

Methods:

A total of 10 nonpaired, fresh-frozen human cadaveric elbows (mean age, 42.2 years; all male) were utilized. Quantitative analysis was performed using a 3-dimensional coordinate measuring device to quantify the location of pertinent bony landmarks, tendons, and ligament footprints of the lateral side of the elbow.

Results:

The extensor carpi radialis brevis was the only humeral footprint found to cross the radiocapitellar joint line, extending a mean 5.9 mm (95% CI, 4.7-7.0) distal to the joint line. With the elbow in full extension, the lateral ulnar collateral ligament (LUCL) humeral footprint was found 7.1 mm (95% CI, 4.7-9.4) anterior and 9.8 mm (95% CI, 8.4-11.2) distal to the lateral epicondyle and 8.6 mm (95% CI, 7.5-9.7) proximal to the radiocapitellar joint line, while the radial collateral ligament humeral footprint was found 6.6 mm (95% CI, 5.5-7.8) anterior and 5.6 mm (95% CI, 4.0-7.2) distal to the lateral epicondyle and 12.7 mm (95% CI, 11.4-14.0) proximal to the radiocapitellar joint line. The center of the ulnar attachment of the LUCL was found 1.4 mm (95% CI, 0.7-2.1) anterior and 2.4 mm (95% CI, 1.2-6.0) proximal to the supinator tubercle and 24.4 mm (95% CI, 22.7-26.1) distal to the radiocapitellar joint line. The center of the ulnar attachment of the annular ligament was found to be 17.3 mm proximal to the supinator tubercle.

Conclusion:

The current study provides measured distances of LUCL and radial collateral ligament attachments in reference to clinically relevant landmarks, which can potentially aid surgeons in performing more anatomic reconstruction or repair of the lateral ligamentous complex of the elbow.

Morphological Features of the Ulnar Collateral Ligament of the Elbow and Common Tendon of Flexor-Pronator Muscles

Background:

The anterior bundle (AB) of the ulnar collateral ligament is the most important structure for valgus stabilization of the elbow. However, anatomic relationships among the AB, posterior bundle (PB) of the ulnar collateral ligament, and common tendon (CT) of the flexor-pronator muscles have not been fully clarified.

Purpose:

To classify the AB, PB, and CT and to clarify their morphological features.

Study Design:

Descriptive laboratory study.

Methods:

This investigation examined 56 arms from 31 embalmed Japanese cadavers. The CT investigation examined 34 arms from 23 embalmed Japanese cadavers with CTs remaining. Type classification was performed by focusing on positional relationships with surrounding structures. Morphological features measured were length, width, thickness, and footprint for the AB and PB and attachment length, thickness, and footprint for the CT.

Results:

The AB was classified as type I (44 elbows; 78.6%), can be separated as a single bundle, or type II (12 elbows; 21.4%), cannot be separated from the PB and joint capsule. The PB was classified as type I (28 elbows; 50.0%), can be separated as a single bundle; type IIa (6 elbows; 10.7%), posterior edge cannot be separated; type IIb (7 elbows; 12.5%), anterior edge cannot be separated; or type III (15 elbows; 26.8%), cannot be separated from the joint capsule. The CT was classified as type I (18 elbows; 52.9%), can be separated from the AB, or type II (16 elbows; 47.1%), cannot be separated from the AB. Significant differences in frequencies of AB, PB, and CT types were identified between men and women. Morphological features were measured only for type I of each structure, and reliability was almost perfect.

Conclusion:

These results suggest that the AB, PB, and CT each can be classified into an independent form and an unclear form. Presence of the unclear form was suggested as one factor contributing to morphological variation.

Clinical Relevance:

This study may provide basic information for clarifying functional roles of the AB, PB, and CT.

Review of Anatomy of the Medial Ulnar Collateral Ligament Complex of the Elbow

PURPOSE OF REVIEW

The importance of both the static and dynamic stabilizers of the medial elbow for the throwing athlete has been demonstrated in recent studies. Furthermore, recent anatomic studies have demonstrated the insertion of the anterior bundle (UCL) to be more distal and elongated, which has implications for surgical reconstruction of the UCL. The purpose of this review is to highlight recent anatomic and biomechanical studies evaluating the anatomy and reconstructions of the medial elbow.

RECENT FINDINGS

Recent literature has highlighted the crucial role of the dynamic stabilizers in resisting valgus force, especially during the throwing motion. The dynamic stabilizers of the medial elbow include the flexor pronator mass, specifically the flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS). The clinical importance of these findings cannot be under stated, as unrecognized dynamic stabilizer injury can lead to increased stress on a native or reconstructed UCL in the throwing athlete. The medial ulnar collateral ligament complex of the elbow has a crucial role in providing both static and dynamic elbow stability. Most notably, the anterior bundle (UCL) provides the primary resistance to valgus and rotational stresses, especially during throwing motion. An understanding of the humeral and ulnar footprints and their relationships with surrounding structures is necessary to restore the native isometry of the medial complex of the elbow during UCL reconstruction. The flexor pronator musculature plays an essential role in dynamic stability, and the intimate relationship of the FCU and FDS with the ulnar insertion of the UCL should be considered to optimize recovery and outcomes with repair or reconstruction.

Transverse ligament of the elbow joint: an anatomic study of cadavers

BACKGROUND

The medial collateral ligament of the elbow joint consists of the anterior oblique ligament (AOL), posterior oblique ligament (POL), and transverse ligament (TL). This study aimed to clarify the structure of the TL, with a focus on the continuity between the TL and AOL.

METHODS

A total of 42 cadavers (18 males, 24 females) were dissected at Aichi Medical University between 2016 and 2018. Cases of elbow deformity or atrophy were excluded, and 60 elbows (15 males, 15 females) were dissected to assess the fibers of both the TL and AOL using a stereomicroscope.

RESULTS

The TL could be detected in all elbows and always continued to the AOL. The TL was classified into 2 types. The TLs continuing to the distal half of the AOL (type I) were observed in 44 elbows (73.3%), whereas the TLs continuing to the entire AOL (type II) were found in 16 elbows (26.7%). Type II TLs were significantly more frequently observed in the elbows of females than in those of males (P = .041). Stereomicroscopic observation revealed that the TL fibers entered perpendicularly to the distal half of the AOL in both types.

CONCLUSIONS

The TL frequently continues to the distal half of the AOL, but rarely continues to the entire AOL. The TLs continuing to the entire AOL were more frequently detected in the elbows of females than in those of males. The TL possibly contributes to medial elbow stability via its continuity to the AOL.

Dual reconstruction of lateral collateral ligament is safe and effective in treating posterolateral rotatory instability of the elbow

PURPOSE

Although reconstruction of the lateral ulnar collateral ligament (LUCL) has been considered the procedure of choice for posterolateral rotatory instability (PLRI), recent studies have reported that the entire lateral collateral ligament complex (LCLC), rather than its posterior part only, contributes to preventing PLRI. Thus, it was hypothesized that dual reconstruction of the radial collateral ligament (RCL) and LUCL for the treatment of elbow PLRI could provide favourable clinical results regardless of the mechanism of injury.

METHODS

This retrospective study reviewed the clinical results of 21 patients who underwent dual reconstruction of the RCL and LUCL between 2011 and 2016. Functional outcomes were assessed using the numeric rating scale (NRS) score, Mayo Elbow Performance Score (MEPS), quick Disabilities of the Arm, Shoulder, and Hand (quick DASH) score, and manual varus instability. To identify any difference in outcomes according to the aetiologies for LCLC insufficiency, our patients were divided into LCLC insufficiency associated with elbow dislocation and that with lateral epicondylitis.

RESULTS

At a median follow-up of 27 months (range 13-65 months), all patients showed resolved instability and achieved a functional arc of motion. In addition, lateral pivot shift tests were negative in all patients. The median MEPS significantly improved after surgery from 70 (range 60-75) to 85 (range 75-100) (p < 0.001), while the median quick DASH score improved from 38.6 (range 26.6-54.5) to 11.4 (range 0-34.1) (p < 0.001). Clinical outcomes according to the aetiology of LCLC insufficiency were not significantly different except for the NRS score.

CONCLUSION

The results suggest that the dual reconstruction technique leads to a clinical outcome similar to that of conventional LUCL reconstruction in LCLC insufficiency regardless of aetiology. In addition, the dual reconstruction technique was technically easier than the conventional LUCL reconstruction technique and may be a potential alternative when a bone tunnel created at the proximal ulna by the original technique has failed.

LEVEL OF EVIDENCE

IV.

Correlation of Force to Deformation of the Anterior Bundle of the Medial Collateral Ligament Through Consideration of Band Laxity

The anterior bundle of the medial collateral ligament (AMCL) resists the loads that arise at the elbow during overhand throwing and has commonly been divided into posterior and anterior bands. While these anterior and posterior bands have been thought to bear the load at different flexion angles, any transition of the load distribution between the two bands is poorly understood and has not considered laxity (slack). This study considers the AMCL as three bands and quantifies the mechanical response to vertical distraction, simulating valgus-load joint opening, through the sequential superposition of the band responses after the elimination of inherent laxity. Eight cadaveric elbow specimens were used for the study. The intact AMCL of each specimen was tested under vertical distraction in a specialized load frame at four elbow flexion angles and then subsequently retested after two longitudinal transections. The greatest laxity at full extension and full flexion belonged to the posterior (1.9 mm) and anterior (2.4 mm) band, respectively. At the lesser and higher flexion angles, the greatest structural stiffness belonged to the anterior and middle band. The overall AMCL was the most structurally stiff at 60°, with approximately 150 N of force required for 2% elongation. This study shows that the different bands of the AMCL may have different load bearing properties at different flexion angles, causing each band to support different proportions of an imposed load. The presence of the laxity may impose a load-bearing delay, causing load-bearing in each band to begin asynchronously. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2027-2034, 2019.

Ultrasonography and magnetic resonance imaging of elbow ligaments: a comparative study

Objective:

To determine the value of ultrasonography in elbow ligament assessment compared to magnetic resonance imaging.

Methods:

A prospective single-center study involving 30 volunteers with no elbow joint changes. Two experienced ultrasound specialists evaluated both elbows of each volunteer, resulting in 60 evaluations per physician and totaling up 120 evaluations. Magnetic resonance images were obtained using a 3-Tesla machine and evaluated by two experienced radiologists, totaling up 120 exams. Each examiner assigned subjective, zero-to-5 scores to ligaments imaged, where zero corresponded to non-identified ligament and 5 to visualization of the entire ligament. The level of significance was set at 5%. Bland-Altman dispersions and plots were prepared for each pair of measurements obtained.

Results:

All ligaments were amenable to sonographic identification; scores of 4 or 5 were assigned by examiners based on ligament visibility. Ligaments could also be identified using magnetic resonance imaging and were assigned scores of 5 by examiners. All ligaments were described as intact and healthy by all four examiners. Comparative analysis of elbow ligament sonographic and magnetic resonance imaging findings did not differ significantly.

Conclusion:

Ultrasonography and magnetic resonance imaging can be considered equivalent modalities for elbow ligament assessment in the hands of experienced examiners.

Understanding the medial ulnar collateral ligament of the elbow: Review of native ligament anatomy and function

The medial ulnar collateral ligament complex of the elbow, which is comprised of the anterior bundle [AB, more formally referred to as the medial ulnar collateral ligament (MUCL)], posterior (PB), and transverse ligament, is commonly injured in overhead throwing athletes. Attenuation or rupture of the ligament results in valgus instability with variable clinical presentations. The AB or MUCL is the strongest component of the ligamentous complex and the primary restraint to valgus stress. It is also composed of two separate bands (anterior and posterior) that provide reciprocal function with the anterior band tight in extension, and the posterior band tight in flexion. In individuals who fail comprehensive non-operative treatment, surgical repair or reconstruction of the MUCL is commonly required to restore elbow function and stability. A comprehensive understanding of the anatomy and biomechanical properties of the MUCL is imperative to optimize reconstructive efforts, and to enhance clinical and radiographic outcomes. Our understanding of the native anatomy and biomechanics of the MUCL has evolved over time. The precise locations of the origin and insertion footprint centers guide surgeons in proper graft placement with relation to bony anatomic landmarks. In recent studies, the ulnar insertion of the MUCL is described as larger than previously thought, with the center of the footprint at varying distances relative to the ulnar ridge, joint line, or sublime tubercle. The purpose of this review is to consolidate and summarize the existing literature regarding the native anatomy, biomechanical, and clinical significance of the entire medial ulnar collateral ligament complex, including the MUCL (AB), PB, and transverse ligament.

Cadaveric Biomechanical Analysis of 3 Lateral Ulnar Collateral Ligament Reconstructions

OBJECTIVE

To biomechanically assess the angular stability provided by 3 techniques for reconstruction of the lateral ulnar collateral ligament.

METHODS

Eight cadaveric elbows were tested with the lateral collateral ligament complex intact, disrupted from the origin at the lateral epicondyle, and reconstructed with 3 different techniques using ulnar bone tunnels: a suture "lasso" or palmaris longus tendon "lasso" both docked with a metal button at the origin, and a doubled-over palmaris longus tendon docked with metal buttons at both the origin and ulnar insertion. Elbows were tested with a physiologic elbow simulator, and varus angular position was quantified with an optical tracking system. Statistical analysis was performed using a repeated measures analysis of variance test to determine whether significance existed, and a Tukey post hoc analysis to compare statistical difference between native, disrupted, and repair states.

RESULTS

There was a statistically significant difference between all repairs and the disrupted state (P < 0.05). The varus angulation after the repairs showed that the suture reconstruction was closest to the native case. The tendon reconstructions were similar to each other but less similar to the native elbow. Quantitatively, the suture reconstruction was within an average of 0.86 degrees of the native elbow throughout range of motion.

CONCLUSIONS

A suture reconstruction was most similar to a native elbow, but both tendon reconstructions significantly improved angular stability under varus gravitational loads.

Reconstruction of the lateral ulnar collateral ligament of the elbow: a comparative biomechanical study

PURPOSE

Posterolateral rotatory instability (PLRI) of the elbow is the result of an insufficient lateral collateral ligament complex (LCLC). Single-bundle reconstruction of the lateral ulnar collateral ligament (LUCL) represents the standard treatment method for chronic PLRI. However, cases of recurrent instability after LUCL reconstruction have been reported. The dual-reconstruction procedure has been described to anatomically restore the LUCL as well as the radial collateral ligament (RCL). It was hypothesized that anatomic reconstruction of the LCLC provides increased stability compared with the conventional technique.

METHODS

Posterolateral rotatory displacement was assessed in eight fresh-frozen human elbows with a maximum load of 20 N. Data were obtained in 0°, 30°, 60°, 90° and 120° of elbow flexion for native specimens, dissected LCLC and three reconstruction methods: (1) single-bundle LUCL reconstruction, (2) single-bundle LUCL reconstruction with RCL augmentation, (3) dual-reconstruction technique (LUCL + RCL).

RESULTS

All reconstruction methods were able to sufficiently restore posterolateral rotatory stability of the elbow over the full range of motion. There were no significant differences between the intact specimens and either reconstruction method. Dissection of the LCLC significantly increased PLRI compared with the other groups (p < 0.001).

CONCLUSION

The less invasive dual-reconstruction technique is confirmed as a safe procedure for anatomic LCLC reconstruction. Primary stability is equal, yet not superior to conventional LUCL reconstruction. Hence, this biomechanical study does not confirm the hypothesis that more anatomic reconstruction techniques could reduce the risk of recurrent instability when compared to conventional LUCL reconstruction.

Avulsion fracture of the supinator crest as an indication for a sustained posterolateral (sub)luxation of the elbow. A case report, anatomical evaluation and review of the literature

The treatment of elbow injuries can be challenging because of the complexity of both anatomy and pathology. We present a rare traumatic avulsion fracture of the supinator crest of the ulna in a 37-year-old patient. Conservative treatment in a long arm cast for four weeks led to satisfactory results. Reproduction of the fracture on a cadaveric elbow clarified that the avulsed fragment holds the insertion of the lateral ulnar collateral ligament (LUCL). The mechanism of trauma that causes this fracture is a posterolateral (sub) luxation of the elbow, which usually causes the LUCL to rupture, but in rare cases the insertion of this ligament can be avulsed. A posterolateral (sub) luxation of the elbow can lead to chronic posterolateral rotational instability and therefore the stability of the elbow should be taken into account in the treatment of patients with such a fracture. A review of the literature concluded that this fracture often is associated with other injuries to the elbow and that it is easily missed on conventional AP and lateral radiographs. CT or MRI imaging and a radial head-capitellum view radiograph can be beneficial. Both conservative and operative treatments have been described with good clinical results.

Ultrasonographic Differentiation of Lateral Elbow Pain

Lateral elbow pain is often attributed to degenerative or posttraumatic impairment of the common extensor tendon. Ultrasonography assesses the soft tissue structures of the lateral elbow, allowing the differentiation between various underlying processes, including angiofibroblastic degeneration, hyaline degeneration, and inflammation, and exclusion of other possible causes of pain such as posterior interosseous and lateral antebrachial nerve compression. Furthermore, the real-time imaging nature of ultrasonography enables the detection of impingement of the lateral synovial fold, degenerative changes in the elbow recess, and elbow posterolateral instability during dynamic maneuvers. Ultrasonography is widely accessible and well tolerated by patients, making it a perfect method for establishing an initial diagnosis and monitoring the healing process. This review describes the possible causes of lateral elbow pain and their ultrasonographic differentiation.

Functional anatomy of the lateral collateral ligament of the elbow

INTRODUCTION

The aim of this study was to analyze the functional anatomy of the lateral collateral ligament complex (LCLC) and the surrounding forearm extensors.

MATERIALS AND METHODS

Using 81 human cadaveric upper extremities, the anatomy of the forearm extensors-especially the anconeus, supinator and extensor carpi ulnaris (ECU)-was analyzed. After removal of aforementioned extensors the functional anatomy of the LCLC was analyzed. The origin of the LCLC was evaluated for isometry. The insertion types of the lateral ulnar collateral ligament (LUCL) were analyzed and classified.

RESULTS

The ECU runs parallel to the RCL to dynamically preserve varus stability. The supinator and anconeus muscle fibers coalesce with the LCLC and lengthen during pronation. The anconeus fibers run parallel to the LUCL in full flexion. The LCLC consists of the annular ligament (AL) and the isometric radial collateral ligament (RCL). During elbow flexion, its posterior branches (LUCL) tighten while the anterior branches loosen. When performing a pivot shift test, the loosened LUCL fibers do not fully tighten in full extension. The LUCL inserts along with the AL at the supinator crest. Three different insertion types could be observed.

CONCLUSIONS

The LUCL represents the posterior branch of the RCL rather than a distinct ligament. It is non-isometric and lengthens during elbow flexion. The RCL was found to be of vital importance for neutralization of posterolateral rotatory forces. Pronation of the forearm actively stabilizes the elbow joint as the supinator, anconeus and biceps muscle work in unison to increase posterolateral rotatory stability.

MRI of the annular ligament of the elbow: review of anatomic considerations and pathologic findings in patients with posterolateral elbow instability

OBJECTIVE

The annular ligament is one of the major stabilizers of the proximal radioulnar joint. However, it is one of the least studied structures in the lateral elbow because of imaging challenges and low pathologic incidence. This article will examine the anatomy of the annular ligament, its biomechanics, and its functional importance. Eight surgically proven cases of annular ligament abnormality in patients with posterolateral and nursemaid elbow, along with the associated findings, are presented.

CONCLUSION

Adequate understanding of the anatomy and familiarity with the associated injuries that can be seen in annular ligament displacement or rupture will improve detection of annular ligament abnormality.

Anatomical parameters in the lateral ulnar collateral ligament reconstruction: a cadaver study

Introduction

The purpose of this study was to indentify the ulnar insertion of the LUCL using the olecranon tip and the radial head as parameters to guide the ligament reconstruction surgery.

Methods

Thirteen elbows of eight fresh cadavers were dissected for the study of the LUCL. The distances between the proximal and distal insertion of the LUCL (footprint), between the radial head and the footprint and between the olecranon tip and the footprint were measure with a digital pachimeter.

Results

The average distance from the radial head to the proximal and distal ulnar insertion of the LUCL was 13.6 and 22.99 mm, respectively. The average distance between the olecranon tip and the proximal and distal ulnar insertion of the LUCL was 38.25 and 47.6 respectively. The mean length of the LUCL footprint was 9.35 mm.

Conclusions

The LUCL insertion has a wide footprint with average 9.3 mm (7.5-11 mm). Ulnar insertion half point be located at 18.2 mm of the radial head and at 42.9 mm of olecranon tip.

Elbow lateral collateral ligament injuries

The lateral collateral ligament (LCL) of the elbow is a complex capsuloligamentous structure critical in stabilizing the ulnohumeral and radiocapitellar articulations. LCL injury can result in elbow instability, allowing the proximal radius and ulna to externally rotate away from the humerus as a supination stress is applied to the forearm. Elbow dislocation is the most common cause of LCL injury, followed by iatrogenic injury. LCL pathology resulting in late recurrent instability is rare but disabling. The diagnosis requires a high index of suspicion, detailed history, and focused physical examination maneuvers. Stress radiographs are often the most useful imaging modality. Despite controversy over the anatomy of the LCL complex and the relative importance of its component structures, treatment of late instability is focused on lateral ligament reconstruction from the humerus to the ulna using tendon grafts with reasonably good outcomes.

Stability of the elbow joint: relevant anatomy and clinical implications of in vitro biomechanical studies

The aim of this literature review is to describe the clinical anatomy of the elbow joint based on information from in vitro biomechanical studies. The clinical consequences of this literature review are described and recommendations are given for the treatment of elbow joint dislocation.

The PubMed and EMBASE electronic databases and the Cochrane Central Register of Controlled Trials were searched. Studies were eligible for inclusion if they included observations of the anatomy and biomechanics of the elbow joint in human anatomic specimens.

Numerous studies of the kinematics, kinesiology and anatomy of the elbow joint in human anatomic specimens yielded important and interesting implications for trauma and orthopaedic surgeons.

Ultrasound assessment of the lateral collateral ligamentous complex of the elbow: imaging aspects in cadavers and normal volunteers

OBJECTIVE

The Lateral Collateral Ligamentous complex (LCL) is an important stabiliser of the elbow. It has a Y-shaped structure with three components. In this study, we sought to describe the ultrasound aspect of the individual components of this ligamentous complex and to evaluate the performance of ultrasound in both cadavers and in normal subjects.

METHODS

Ten cadaveric elbow specimens underwent high-frequency ultrasound. Two specimens were sliced and two were dissected for anatomical correlation. Ten elbows of normal subjects were also evaluated by ultrasound. The findings were compared.

RESULTS

The three components of the LCL could be visualised in all specimens and normal subjects with the exception of the proximal portion of one specimen. In 80% of the specimens and 100% of the healthy volunteers the proximal portion of the LCL could be separated from the extensor tendons.

CONCLUSION

High-resolution ultrasound can assess all components of the LCL of the elbow and can distinguish them from surrounding structures.

Detailed MRI-anatomic study of the lateral epicondyle of the elbow and its tendinous and ligamentous attachments in cadavers

OBJECTIVE

The objective of our study was to document discrete bone landmarks in the lateral epicondyle of the humerus that represent the "footprints" of those tendons and ligaments that attach to it using MRI-anatomic correlation in cadavers.

MATERIALS AND METHODS

Thirty-three dried humeral specimens were inspected to document bone landmarks in the lateral epicondyle. MRI with anatomic correlation was performed in 10 additional cadaveric elbows. The locations of the tendinous and ligamentous attachments to the lateral epicondyle were determined with respect to the same osseous landmarks.

RESULTS

The surface of the lateral epicondyle ranged from a flat surface to a surface with up to six discrete landmarks: superior tubercle, anterior tubercle, posterior tubercle, intertubercular sulcus, rough area surrounding the tubercles, and epicondylar ridge. The radial collateral ligament attached to the superior aspect of the intertubercular sulcus and inferior aspect of the superior tubercle and was indistinguishable from the attachment of the lateral ulnar collateral ligament. The extensor carpi radialis brevis, extensor digitorum communis, and extensor digiti minimi had a common origin in the superior aspect of the lateral epicondyle. The extensor carpi ulnaris tendon arose from the posteroinferior aspect of the lateral epicondyle.

CONCLUSION

Our investigation documents osseous landmarks that are useful in the identification of the footprints of the tendons and ligaments that attach to the lateral epicondyle. Knowledge of these structures contributes to correct interpretation of MR images in persons with tendinous and ligamentous abnormalities in this region.

Can osseous landmarks in the distal medial humerus be used to identify the attachment sites of ligaments and tendons: paleopathologic-anatomic imaging study in cadavers

OBJECTIVE

To describe osseous landmarks that allow identification of the attachments of the ligaments and tendons in the distal medial aspect of the humerus.

MATERIALS AND METHODS

Reliable osseous landmarks in the distal medial aspect of the humerus were identified in 34 well-preserved specimens from a paleopathologic collection. These osseous landmarks were then sought in magnetic resonance (MR) images of ten cadaveric elbow specimens so that the ease of their visualization and optimal imaging plane could be assessed. To assign these osseous landmarks to specific attachments of the tendons and ligaments in the distal medial humerus, we cut the specimens in slices and photographed and examined them. Subsequently, the prevalence of these osseous landmarks as well as the attachment sites of the tendons and ligaments in this location was determined.

RESULTS

We determined ten reliable osseous landmarks in the distal medial aspect of the humerus, their prevalence and ease of identification, and their relationship to the attachments of the tendons and ligaments at the medial distal humerus.

CONCLUSION

It is possible to use osseous landmarks at the distal medial humerus to facilitate identification of the different attachments of tendons and ligaments when MR images of the elbow are assessed.

Ligament fibre recruitment of the elbow joint during gravity-loaded passive motion: an experimental study

BACKGROUND

Knowledge of elbow collateral ligament length during passive motion is essential in understanding ligament physiology and pathology, such as tightness and instability.

METHODS

Five anatomical unembalmed specimens were passively placed in six flexion positions together with three forearm rotations, using equipment with gravity as motion force. These 18 positions were recorded using CT-scan. Three-dimensional data of ligament insertions were obtained through anatomical millimetre sections. Ligament length was measured in each position.

FINDINGS

In neutral rotation, the lateral collateral ligament was long between 0 degrees and 30 degrees as well as at 90 degrees, and short between about 60 degrees and 120 degrees of flexion. In pronation, it was long at about 0 degrees and between 60 degrees and 120 degrees, short at about 30 degrees of flexion. In supination, it was long at about 30 degrees and 90 degrees and short between 120 degrees and 150 degrees of flexion. In any forearm rotation, the highest length of the anterior bundle of the ulnar collateral ligament was measured at about 90 degrees, its smallest length between 120 degrees and 150 degrees of flexion, position at which the posterior bundle length was greatest.

INTERPRETATION

At 60 degrees of flexion, the collateral ligaments were slackened in any forearm rotations. Forearm rotation plays an indirect role in the posterolateral stability of elbow as it changes length of the lateral collateral ligament. This ligament can be tested passively at 90 degrees of flexion in supination, the anterior bundle of the ulnar collateral ligament between 0 degrees and 30 degrees in neutral rotation and the posterior bundle between 120 degrees and 150 degrees in neutral rotation.

Normal MR imaging anatomy of the elbow

The functional complexity achieved at the elbow is a reflection of the sophisticated architecture that embodies this articulation. In addition to challenging anatomic relationships to conceptualize, there are many anatomic variations that exist in the osseous, capsular, and muscular structures. This article offers a detailed description of the structural and imaging anatomy of the elbow, information that establishes the foundation of imaging interpretation of internal derangements.

Anatomical basis of arthroscopic capsulotomy for elbow stiffness

Stiffness is a frequent condition in elbow pathologies, both traumatic and non-traumatic, and usually requires an operative treatment including an anterior capsulotomy. Elbow arthroscopy is certainly an alternative to surgery, but the technique of arthroscopic capsulotomy remains controversial. Our aim was to study the anterior elbow capsule anatomy to recommend an efficient and safe arthroscopic capsulotomy. We dissected ten cadaveric elbows and analyzed the insertions of the anterior capsule, their variations and the relationships with the surrounding neurovascular structures (radial and median nerve, brachial artery). The influence of elbow flexion was studied on fresh elbows with radioscopic evaluation. The distances between the anterior capsule and the neurovascular structures were measured at four reference levels. The insertions of the anterior capsule were also studied on the embalmed elbows. The radial nerve is always the closest structure to the capsule, but in this study it was always protected by the brachialis muscle. The distance between the anterior capsule and the neurovascular structures is consistently higher on the proximal side, regardless of which structure is considered. The 90 degrees flexion position allows the best capsular distension and offers optimal security with regard to neurovascular structures. All arthroscopic surgeons are concerned about potential neurovascular complications (varying from 0 to 14% in the literature). Previous anatomical studies examined the relationships between the arthroscopic portals and the neurovascular structures. This study developed a precise description of the relationship between the anterior capsule and the surrounding neurovascular structures, which let us recommend technical parameters to conduct a safe arthroscopic capsulotomy.

Normal MR imaging anatomy of the elbow

The functional complexity achieved at the elbow is a reflection of the sophisticated architecture that embodies this articulation. In addition to challenging anatomic relationships to conceptualize, there are many anatomic variations that exist in the osseous, capsular, and muscular structures. This article offers a detailed description of the structural and imaging anatomy of the elbow, information that establishes the foundation of imaging interpretation of internal derangements.