Functional anatomy of the lateral collateral ligament complex of the elbow: morphology and strain

The anatomy of the lateral ulnar collateral ligament (LUCL) of the elbow was investigated in 26 fresh frozen cadavers. Two types of insertion of the LUCL were originally described but we found another type which is characterized by a broad single expansion along with a thin membranous fibre. Strain on the LUCL was measured in situ during extension and flexion with the forearm in supination, pronation and neutral. Strain in the proximal fibres started to occur at around 32 degrees flexion and peaked at between 50 degrees and 60 degrees flexion. Strains measured in the distal fibres were smaller in magnitude. Forearm rotation had little effect on strain during extension to flexion. Based on these results, we conclude that the LUCL functions in unison with the annular ligament.     

Anatomic and histologic studies of lateral collateral ligament complex of the elbow joint

We studied the gross and histologic anatomic characteristics of the lateral collateral ligament complex of the elbow joint from 15 cadavers to demonstrate its cross-sectional anatomy. The lateral ulnar collateral ligament adheres closely to the supinator, the extensor muscles, its intermuscular fascia, and the anconeus muscle and lies posterior to the radial collateral ligament. The lateral ulnar collateral ligament itself was identified with microscopy as a slender, poor structure consisting of the thick area of the posterolateral capsuloligamentous layer and a poorer structure than the anterior bundle of the medial collateral ligament as the primary stabilizer of the elbow joint. We believe that the lateral ulnar collateral ligament contributes to rather than is a major constraint to the posterolateral rotatory instability as part of the lateral collateral ligament complex with the surrounding tissues.     

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.     

肘关节外侧副韧带复合体修复治疗急性后外侧旋转不稳定的临床疗效

目的探讨肘关节外侧副韧带复合体修复治疗急性后外侧旋转不稳定的临床疗效。 方法选择2013年6月至2017年12月上海新华医院连续收治的急性肘关节后外侧旋转不稳定患者20例,其中手术组11例,对照组（保守治疗）9例。20例患者均有肘关节脱位史。在麻醉下检查时,20例患者侧方轴移试验和后外侧抽屉试验均为阳性。手术组患者均使用带线锚钉修复外侧副韧带复合体。术后随访评估患者的疼痛、活动范围及稳定性,采用视觉模拟评分和Mayo肘关节功能评分进行评价和评级。 结果20例患者经过6~24个月的随访,手术组和对照组治疗后视觉模拟评分分别为（0.27±0.19）分和（1.56±0.41）分,Mayo肘关节功能评分分别为（91.27±2.28）分和（77.78±4.96）分,手术组明显优于对照组,差异有统计学意义。 结论急性肘关节后外侧旋转不稳定的正确诊断对于治疗方案的选取非常重要。肘关节外侧副韧带复合体修复术可以很好地恢复肘关节的稳定性和功能。     

Non-anatomical reconstruction of lateral ulnar collateral ligament of the elbow after tumor resection

We present the case of an 80-year-old man with a tumor recurrence on his right arm 6 years after initial treatment. The lateral aspect of the elbow joint, involving overlaying skin, muscles, tendons, joint capsule, lateral collateral ligament complex, the lateral 1/3 of the capitellum, and lateral epicondyle of humerus were excised in the tumor resection. Intraoperative assessment revealed multidirectional instability of the elbow, and joint stabilization was needed. Because the lateral epicondyle was resected, graft placement in an anatomical position was impossible to carry out. Therefore, non-anatomical reconstruction of lateral ulnar collateral ligament with palmaris longus tendon graft was performed. The skin was reconstructed using an antegrade pedicled radial forearm flap. For wrist extension reconstruction, the pronator quadratus tendon was transferred to the extensor carpi radialis brevis tendon. One year after the operation, elbow range of motion was 5–130°. The patient remains symptom free. The Mayo elbow performance score is good. The Musculoskeletal Tumor Society rating score is excellent. To our knowledge, this is the first report of an elbow lateral ulnar collateral ligament reconstruction after tumor resection.     

Lateral collateral ligament instability of the elbow

Lateral elbow support is provided by a combination of bony anatomy and the ligaments and tendons that originate at the lateral epicondyle. Instability is typically posttraumatic in nature. In the acute setting of elbow fracture-dislocation, restoration of lateral soft tissue support can be typically accomplished by a direct repair of the lateral ligament and extensor tendon origins to the humeral epicondyle. In chronic settings, a reconstruction is most commonly necessary using a free tendon graft. Indications and surgical techniques are discussed.     

Relative role changing of lateral collateral ligament on the posterolateral rotatory instability according to the knee flexion angles: a biomechanical comparative study of role of lateral collateral ligament and popliteofibular ligament

Purpose

This cadaveric study assessed the relative role of the lateral collateral ligament (LCL) and popliteofibular ligament (PFL) in limiting tibia external rotation.

Methods

Eight paired cadaveric knees were divided into two groups. The specimens were mounted on a rotational wheel and 5?Nm external rotation torque was applied before and after cutting the ligaments at 0°–30°–60°–90° knee flexion. Three cutting steps were applied: (1) PT (popliteus tendon)-, (2) LCL-, (3) PFL in group I, and (1) PT-, (2) PFL-, (3)LCL in group II. Increased external rotation at each step was taken as the ratio of final external rotation at the end of step 3. Repeated measure ANOVA and a Mann–Whitney U test were used for statistical analysis.

Results

At step 2, the ratio of increased external rotation after cutting the LCL (group I) was similar to the ratio after cutting the PFL (group II) at 0° and 30° flexion, but that of group I was lower than group II at 60° and 90° flexion (p?=?0.029 and p?=?0.029). At step-3, the ratio after cutting the LCL (group II) was less than the ratio after cutting the PFL (group I) at 90° flexion (p?=?0.029).

Conclusion

The PFL and LCL play equally important roles in limiting external rotation at the knee extended position (0°, 30°) but the LCL contribution becomes smaller than PFL at the flexed position (60°, 90°).     

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

BackgroundVarus 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.MethodsBetween 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).ResultsThe 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.ConclusionCoronoid 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.     

Ulnar collateral ligament tears of the elbow joint

The functions of the elbow in 13 cases of ulnar collateral ligament (U.C.L.) tears without gross intraarticular complications were retrospectively evaluated. Ten cases had been surgically repaired, and the remaining three cases were treated conservatively. Follow-up examinations were performed on all of the patients. There was a significant difference in valgus instability between operatively treated patients and conservatively treated patients (operatively treated patients averaged 5.1 degrees, while conservatively treated patients averaged 8 degrees). Two cases of conservatively treated patients complained of elbow joint pain while playing sports or working. Conversely, one of the operatively treated patients complained of numbness in the fifth finger. However, the remaining cases had no symptoms, even while playing sports or working. Valgus instability of the elbow joint results in little inconvenience in daily life, but it is disabling in patients performing heavy labor or vigorous sports.     

The collateral ligaments of the elbow: anatomy and clinical correlation

Stability of the elbow is provided by the congruous nature of the bony articulations and the medial and lateral collateral ligament complexes. The medial ligament provides additional support to valgus stress. The lateral ligament prevents rotational instability between the distal humerus and the proximal radius and ulna. Collateral ligament insufficiency typically is posttraumatic and can occur on either side of the joint. An understanding of the normal anatomy is required to make the correct diagnosis and complete a successful surgical reconstruction.