Functional anatomy of the lateral collateral ligament of the elbow

Anconeus-sparing minimally invasive approach for lateral ulnar collateral ligament reconstruction using a triceps tendon autograft is an effective and safe treatment for chronic posterolateral instability of the elbow

BACKGROUND

Surgical treatment helps to restore stability of the elbow in patients with posterolateral rotatory instability (PLRI). The anconeus muscle is one of the most important active stabilizers against PLRI. A minimally invasive anconeus-sparing approach for lateral ulnar collateral ligament (LUCL) reconstruction using a triceps tendon autograft has been previously described. The purpose of this study was to evaluate the outcome of this intervention and identify risk factors that influenced the clinical and patient-reported outcomes.

METHODS

Sixty-one patients with chronic PLRI and no previous elbow surgery who underwent surgical reconstruction of the LUCL using a triceps tendon autograft in a minimally invasive anconeus-sparing approach during 2012 and 2018 were evaluated. Outcome measures included a clinical examination and the Oxford Elbow Score (OES) and the Mayo Elbow Performance Score (MEPS) questionnaires. Subjective patient outcomes were evaluated with the visual analog scale (VAS) for pain and the Subjective Elbow Value (SEV). Integrity of the common extensor tendons and centering of the radial head were assessed preoperatively on standardized magnetic resonance images (MRIs).

RESULTS

Fifty-two patients were available at final follow-up. The mean age of patients was 51 ± 12 years with a mean follow-up of 53 ± 14 months (range 20-76). Clinical examination after surgery (n = 41) showed no clinical signs of instability in 98% of the patients (P < .001) and a nonsignificant improvement in range of motion. OES, MEPS, and VAS scores averaged 40 ± 10 of 48 points, 92 ± 12 of 100 points, and 1 ± 2 points, respectively, all corresponding with good or excellent outcomes. The SEV was 88%, indicating very high satisfaction with the surgery. Only 1 patient had revision surgery due to pain, and there were no reported postoperative complications in this cohort. A radial head subluxation in the MRI correlated significantly with worse postoperative outcomes.

CONCLUSIONS

The anconeus-sparing minimally invasive technique for posterolateral stabilization of the elbow using a triceps tendon autograft is an effective and safe treatment for chronic posterolateral instability of the elbow with substantial improvements in elbow function and pain relief with a very low rate of persistent clinical instability.

Elbow anatomy in perspective of joint capsule and surrounding aponeuroses: a narrative review

Background

Because of the proximity of several ligaments, aponeuroses, and capsule in the limited area of the elbow joint, the precise anatomy is difficult to understand. In the current narrative review, we focused on two anatomical perspectives: the capsular attachment and structures consisting of ligaments.

Methods

Based on the previously performed studies regarding the elbow anatomy, a narrative review was prepared in terms of the capsular attachment and structures consisting of ligaments.

Results

At the tip of the coronoid process, the joint capsule attaches roughly 6 mm distal to its tip with 6-12 mm length. On the lateral epicondyle of the humerus, the capsular attachment at the anterior part of the extensor carpi radialis brevis origin is narrower than the one distal to it. A single interpretation of the lateral collateral ligament is the capsulo-aponeurotic membrane, which is composed of the joint capsule intermingling with the supinator aponeurosis. The anterior bundle of the ulnar collateral ligament could be interpreted as the grossly separated collagenous structure from the tendinous complex, which is composed of the tendinous septum between the flexor digitorum superficialis and pronator teres muscle, the medial part of the brachialis muscle, and deep aponeurosis of the flexor digitorum superficialis muscle.

Discussion

Based on these perspectives, ligaments could function as a "static-dynamic" stabilizer rather than a simple static one.

The Relationship between the Bevel of the Radial Head Epiphysis and the Posterior Synovial Fringe During Rotation of the Elbow: An Ultrasonography Study with Possible Implications Regarding the Pathophysiology of Nursemaid's Elbow

BACKGROUND

Nursemaid's elbow is the most common upper extremity injury in children under 5 years of age. However, the exact pathomechanism underlying the nursemaid's elbow remains elusive, and approximate one-third of patients present with a nonclassical history. Using a high-frequency ultrasound probe, we attempted to determine the relationship between the anterior edge of the posterior synovial fringe and the peripheral rim of the radial head epiphysis during rotation. It is possible that the primary reason for the nursemaid's elbow is due to the pronator position.

METHODS

Twenty-one patients had a history of nursemaid's elbow and had a successful reduction before enrollment in this study. A high-frequency linear array 6 to 24 MHz hockey stick transducer was used to detect small morphologic changes in the peripheral rim of the radial head epiphysis and the posterior synovial fringe during rotation of the capitellum-radial joint.

RESULTS

In complete pronation, the anterior edge of the posterior synovial fringe contacts the beveled articular surface of the radial head peripheral rim in all 21 patients. In neutral and complete supination, the anterior edge of the posterior synovial fringe contacts the convexly nonarticular surface of the radial head peripheral rim and extends deep into the foveal radius. The posterior synovial fringe and the capsule-aponeurotic membrane were tightened in passive pronation in all 21 cases. The posterior synovial fringe and the capsule-aponeurosis membrane were all loose in the neutral and supination positions.

CONCLUSION

The anterior edge of the posterior synovial fringe touches the beveled peripheral rim of the radial head epiphysis during complete pronation, and the tension of the lateral collateral ligament complex during pronation may further cause unstable conditions of the anterior edge of the posterior synovial fringe. We hypothesized that the beveled peripheral rim of the radial epiphysis and its relationship with the anterior edge of the posterior synovial fringe could be the reason why nursemaid's elbow only occurs while the elbow is in the pronator position.

No difference in torque load to failure between split anconeus fascia transfer and autograft palmaris longus tendon for reconstruction of the lateral ulnar collateral ligament

Background

The split anconeus fascia transfer (SAFT) is an option for reconstruction of the lateral ulnar collateral ligament (LUCL) in chronic posterolateral rotatory instability (PLRI) of the elbow with potential advantages of using only local tissue within the surgical exposure and not requiring ulnar fixation. This study aimed to assess SAFT strength compared to a traditional free graft reconstruction in a PLRI biomechanical model.

Methods

To measure biomechanical strength, eight cadaveric upper extremity pairs were utilized. Within each pair, one specimen was randomly assigned to LUCL reconstruction with autograft palmaris longus and the other to SAFT reconstruction. Torque load to failure was assessed on a load frame with the elbow in 30 degrees of flexion, 5 degrees of valgus, and 25 N axial load as the elbow was brought into external rotation. Torque load to failure was compared between the two reconstruction techniques.

Results

No difference was found in the torque load to failure between SAFT specimens compared to palmaris longus autograft specimens (mean 14.6 ± 4.4 Nm vs. mean 11.3 ± 3.9 Nm; P = .16).

Discussion

In this biomechanical study, the SAFT LUCL reconstruction provided torque load to failure similar to that of the traditional technique. These findings suggest that the SAFT technique warrants continued study as a biomechanically sound option for LUCL reconstruction in the setting of elbow PLRI.

Clinical and Functional Results of Lateral Ulnar Collateral Ligament Repair for Posterolateral Rotatory Instability of the Elbow

Background Posterolateral rotatory instability of the elbow arises from damage to the lateral ulnar collateral ligament (LUCL). While various methods exist for reconstructing or repairing the LUCL's attachment to the humerus, the most effective approach remains debatable. This study aims to assess the outcomes of directly repairing the LUCL when the injury occurs at the humeral attachment. Methodology This retrospective study, conducted at the Royal Berkshire Foundation Trust NHS hospital in Reading, UK, assessed outcomes through a review of 15 patients who underwent direct repair of the lateral ulnar collateral ligament between 2017 and 2022, evaluating a range of motion, the Mayo Elbow Performance Score, and the Nestor grading system. Results This study included nine males and six females, with an average age of 38.8 years. Most LUCL injuries arose from elbow dislocation (46.7%). The average follow-up period for patients was 26 months. At the final assessment, the mean Mayo Elbow Performance Score reached 99. According to the Nestor grading system, 12 patients achieved excellent results, and three had good outcomes. On average, there was an 11.3° loss of final extension and 5° of final flexion, yet achieving a comparable pronation-supination arch to the contralateral side. Conclusion Direct repair of the LUCL for elbow posterolateral rotary instability yielded excellent outcomes, obviating ligament reconstruction. Recognized as minimally invasive, it accelerates recovery, minimizes trauma, and offers a cost-effective procedure for managing instability.

The effect of lateral collateral ligament repair tension on elbow stability: An in vitro biomechanical study

BACKGROUND

The aim of this study was to determine the optimal repair tension of the lateral collateral ligament of the elbow by performing simulated active flexion with the arm in the varus gravity loaded position using an in vitro elbow simulator.

METHODS

Eight cadaveric specimens were mounted in the varus gravity loaded orientation onto an elbow motion simulator. Four states were studied (intact, lateral collateral ligament injured, and 15 N and 20 N lateral collateral ligament repairs) with the forearm in supination and pronation. An electromagnetic tracking system was used to measure joint kinematics during active elbow flexion.

FINDINGS

There was no difference in ulnohumeral rotation between the intact state and the 15 N repair (P = .150 for pronation; P = 1.0 for supination) or the 20 N repair (P = 1.0 for pronation; P = .568 for supination). For varus-valgus angulation, the 20 N repair was not statistically different from the intact state (P = .059 in pronation; P = 1.0 in supination).

INTERPRETATION

Repair of the lateral collateral ligament following injury can restore joint kinematics with the arm in the varus position. A repair tension of 20 N was successful in restoring joint stability for simulated active motion with the forearm in pronation and supination. This study shows that when the lateral collateral ligament is repaired with adequate tension, avoidance of the varus position may not be as crucial during early motion.

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.

A modified trans-anconeus approach to facilitate fixation of a posterior radial head fracture: a cadaveric feasibility study

Fixation of radial head fracture with minimally invasive posterior approach remains a significant challenge. The aim of this study was to determine the feasibility of trans-anconeus posterior elbow approach and to observe lateral ulnar collateral ligament (LUCL) in extended elbows. This cadaveric study was performed in twenty upper limbs of fresh fixed adult male cadavers. An oblique incision was made in the middle segment of anconeus until the lateral ligament complex and the joint capsule had been revealed. A deep dissection was explored to observe the anatomical relationship of the LUCL to the anconeus. Measurements of the LUCL were recorded while the elbow was fully extended. The mean distance between the edge of the radial head and the proximal insertion of the LUCL was 13.3 mm (11.5-16.2 mm); the mean distance between the edge of the radial head and the distal insertion of the LUCL was 20.9 mm (19.2-23.4 mm); the distance between the edge of the radial head and the distal edge of the annular ligament was 11.2 mm (8.22-11.7 mm). By estimate correlation of the previous measurements, the direct and accessible way to expose the posterolateral articular capsule of the elbow joint was through a window in medial 2/3 of the middle segment of anconeus muscle. These trans-anconeus approach is useful. It provides good visualization, facilitates applying the implants, and lessens the risk of radial nerve injury. Awareness of the anatomy is mandatory to avoid injury of LUCL.

Locking suture repair versus ligament augmentation-a biomechanical study regarding the treatment of acute lateral collateral ligament injuries of the elbow

BACKGROUND

Lateral collateral ligament (LCL) tears are frequently observed in fractures and dislocations of the elbow. Recent biomechanical evidence suggests that additional ligament augmentation may improve repair stability. The aim of this biomechanical in-vitro study was to compare the resistance of a locking suture repair of the LCL with a ligament augmentation technique.

MATERIAL AND METHODS

Eight fresh frozen cadaveric elbows were evaluated for stability against varus/posterolateral rotatory forces (3 Nm). A strain gauge (µm/m; negative values) was placed at the origin and insertion of the lateral ulnar collateral ligament (LUCL) and cyclic loading was performed for 1000 cycles. We analyzed three distinct scenarios: (A) native LCL, (B) locking transosseou suture repair of the LCL, (C) simple LCL repair with additional ligament augmentation of the LUCL.

RESULTS

The mean measured strain was - 416.1 µm/m (A), - 618 µm/m (B) and - 288.5 µm/m (C) with the elbow flexion at 90°; the strain was significantly higher in scenario B compared to C (p = .01). During the cyclic load (1000) the mean measured strain was - 523.1 µm/m (B) and - 226.3 µm/m (C) with the elbow flexion at 60°; the strain was significantly higher in scenario B compared to C (p = .01). No significant difference between the first and the last cycles was observed (p = .09; p = .07). One failure of the LCL repair was observed after 1000 cycles; none of the ligament augmentations failed.

CONCLUSION

Ligament augmentation (C) provides higher resistance compared to the native LCL (A) and to the locking suture repair technique (B). Both techniques, however, hold up during 1000 cycles. While ligament augmentation might enhance the primary stability of the repair, future clinical studies have to show whether this increase in resistance leads to negative effects like higher rates of posttraumatic elbow stiffness.

LEVEL OF EVIDENCE

Basic science study, biomechanics.

The lateral collateral ligament complex of the elbow in a Thai population: an anatomical study of 56 cadaveric specimens

The purpose of this study was to investigate the anatomical features of the lateral collateral complex (LCC) of the elbow in a Thai population. We dissected 56 cadaveric elbows and described the LCC three-dimensionally in sagittal and coronal planes. We found that the characteristics differed from previous reports in other ethnic populations. In the sagittal plane, the centre of the origin of the LCC was located 3 mm anteriorly and 4 mm inferiorly to the apex of the lateral humerus epicondyle, and in the coronal plane it was 4 mm deep. The vertical distance between the origin of the lateral ulnar collateral ligament (LUCL) and the lateral epicondyle and the distance from the LUCL insertion to the border of the ulnar bone differed significantly between sexes. These data may be useful for surgeons during reconstruction of injures to the LCC of the elbow.Level of evidence: V.

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.

Coronal Shear Fractures of the Distal Humerus: A Review of Diagnosis, Treatment, and Outcomes

Fractures of the capitellum and trochlea are uncommon fractures of the elbow and can be challenging to treat due to their size, location, and articular nature. Because of their intra-articular nature and predilection toward displacement, these fractures are typically treated operatively. Furthermore, capitellum fractures have high rates of associated injuries, including radial head fractures or lateral collateral ligament injury in ~30% to 60% of patients. In addition to open reduction internal fixation, operative options include fragment excision, arthroscopic assisted reduction and fixation, and elbow arthroplasty. In this article, we undertake a comprehensive literature review of capitellum fractures of the distal humerus, in an attempt to summarize the existing body of evidence and propose areas of future study.

Relationship Between the Lateral Collateral Ligament of the Elbow and the Kocher Approach: A Cadaver Study

PURPOSE

The lateral ulnar collateral ligament (LUCL) is considered to be the portion of the lateral collateral ligament playing the most important stabilizing role. Iatrogenic forms of posterolateral rotatory instability have been described. The Kocher approach is a popular approach to the lateral side of the elbow. The aim of this study was to describe the relationship between the LUCL and the Kocher interval.

METHODS

The Kocher interval was identified and marked in 20 cadavers. The LUCL was identified and the distance between the LUCL insertion on the tubercle of the cresta supinatoris and the Kocher interval was calculated (TK distance). This distance was considered 0 if the Kocher interval was directly above the tubercle, as a positive value if it was anterior to the tubercle, and as a negative value if it was posterior. Finally, the Kocher interval was sharply opened, and elbow stability was tested using the posterolateral rotatory drawer test.

RESULTS

A discrete LUCL was identified in 16 specimens. The mean TK distance was -2.3 ± 4.4 mm (range, -11 to +10). The median TK distance was -3 mm. The posterolateral rotatory drawer test was positive for subluxation after the sharp incision of the Kocher interval in 15 specimens. The median TK distance was significantly higher in the stable group (+2 mm) than in the unstable group (-3 mm).

CONCLUSIONS

The LUCL often lies beneath the Kocher interval and is at risk during the Kocher approach.

CLINICAL RELEVANCE

Iatrogenic forms of posterolateral rotatory instability could result from this approach.

Lateral ulnar collateral ligament (LUCL) reconstruction for the treatment of recalcitrant lateral epicondylitis of the elbow: a comparison with open débridement of the extensor origin

Background

Based on the controversy over whether the extensor tendon is the only lesion of lateral epicondylitis of the elbow and numerous reports of concomitant lateral collateral ligament involvement, potential damage to the lateral collateral ligament complex should be considered for the treatment.

Methods

About 25 elbows in 23 patients (débridement group) and 22 elbows in 20 patients (reconstruction group) who were diagnosed with lateral epicondylitis and had an average of 22 months of symptoms revealing anatomical lesion on MRI were included. The capitellum-sublime tubercle-radial head (CSR) angle was measured on both sides preoperatively, and the visual analog scale (VAS) and Mayo elbow performance score (MEPS) were measured over 12 months, postoperatively.

Results

The initial preoperative mean VAS was statistically significant with 4.6 in the débridement group and 6.5 in the reconstruction group (P < .05). Postoperative VAS was continuously decreased in both groups with no significant difference at each assessment period (P < .05) but showed more rapid improvement in the reconstruction group compared with the débridement group. For MEPS, the reconstruction group showed significant improvement during the follow-up periods, and at the final follow-up MEPS, 3 cases in the débridement group and 0 cases in the reconstruction group showed a poor result, which was considered as surgery failure. The CSR angle of the affected side (7.2 ± 1.9) was significantly larger than that of the normal side (3.6 ± 1.5) (P < .05) in the reconstruction group. Increased CSR by more than 5 degrees was identified as a significant predictive indicator for potential concomitant ligament insufficiency (area under curve = 0.875, P < .001) showing 80.9% of the sensitivity, 82.1% of the specificity.

Conclusions

In the surgical treatment of recalcitrant lateral epicondylitis, lateral ulnar collateral ligament reconstruction added to the débridement of extensor origin may provide better results for the patients with suspicious lateral ligament insufficiency or failed previous surgery.

Early Rehabilitation after Surgical Repair of Medial and Lateral Collateral Elbow Ligaments: A Report of Three Cases

Elbow ligament injuries are commonly caused by overuse; degeneration; and trauma; such as from a fall or collision. The purpose of this study was to present the results of three cases involving patients undergoing early rehabilitation after surgical treatment for complex injury of the elbow medial collateral ligament (MCL) and lateral collateral ligament (LCL). Two patients were non-athlete middle-aged women and one was a recreational judo player. Surgery was performed through open incision or arthroscopically. Rehabilitation consisted of range of motion (ROM) exercise; muscle strength restoration; and neuromuscular training. Passive ROM exercise and isometric strength exercise began at 7 days; isotonic strength training at 6 weeks; and neuromuscular training at 3 months after operation. Center- and home-based methods of exercise participation were combined. Center-based exercises were performed 1–2 times per week for the first 6 months and 1–2 times per month for the next 6 months. Patients also performed home-based and self-monitoring exercise. Examinations included ROM using a goniometer; muscle strength test using isokinetic equipment; and Oxford elbow score. In the six months after surgery; flexion ROM was 130° for Case A (health side 145°), 110° for Case B (health side 145°), and 135° for Case C (health side 135°); grip strength was restored to 13 kg (health side 28 kg), 16 kg (health side 25 kg), and 38 kg (health side 52 kg); and isokinetic flexion strength was improved to 30 Nm (health side 58 Nm), 21 Nm (health side 50 Nm), and 72 Nm (health side 80 Nm), respectively. In conclusion; patients who underwent early rehabilitation recovered ROM and muscle strength and returned to daily activity without any side effects. This study showed that patients with elbow MCL and LCL injuries took approximately 3 months to recover meaningful ROM; approximately 6 months to recover muscle strength; and 4–8 months to play light recreational sports. In addition; it took patients 6 weeks to return to their daily activities and 6 months to improve questionnaire scores in their function and pain during daily activity. In follow-up two years after surgery; all three patients had full ROM and muscle strength within 10% of the healthy side

Biomechanical assessment of lateral ulnar collateral ligament repair and reconstruction with or without internal brace augmentation

Background

Surgical treatment of posterolateral rotatory instability (PLRI) using primary repair or reconstruction of the lateral collateral ligament complex have proven inconsistent. This study aimed to test the hypothesis that augmentation of LUCL repair or palmaris longus tendon reconstruction using a suture tape augmentation would be associated with less rotational displacement and greater torque load to failure (LTF) compared with nonaugmented constructs.

Methods

Cadaveric elbows (n = 12 matched pairs) were used. Baseline stiffness and displacement values were obtained. The LUCL was transected followed by repair alone, repair with augmentation, reconstruction with palmaris longus graft, or reconstruction with augmentation. Specimens were retested including torque LTF. Paired t tests were performed to assess the biomechanical effects of augmentation.

Results

Augmentation was associated with higher LTF than repair and reconstruction alone (P = .008 and .047, respectively). Displacement was less with augmentation in reconstruction groups (P = .048) but not in repair groups. Suture tape augmentation maintained rotational stiffness better than repair alone (P = .01). Although reconstruction with augmentation maintained rotational stiffness better than nonaugmented reconstruction, the differences were not statistically significant (P = .057). Mode of failure for repair alone was predominantly suture pulling through repaired ligament. Augmented repairs primarily failed at the anchor-bone interface. Modes of failure for both reconstruction groups were similar, including graft tearing and/or slipping at the anchor.

Conclusion

When positioned in neutral forearm rotation and 90^o of flexion to simulate postoperative conditions, augmentation of LUCL repair or tendon reconstruction using suture tape is associated with better resistance to rotational loads compared with nonaugmented repair or reconstruction, while maintaining near-native rotational stiffness.

LUCL internal bracing restores posterolateral rotatory stability of the elbow

PURPOSE

Posterolateral rotatory instability (PLRI) of the elbow occurs from an insufficient lateral collateral ligament complex (LCLC). For subacute LCLC injuries, lateral ulnar collateral ligament (LUCL) internal bracing rather than reconstruction may be a viable option. The purpose of the study was to compare the stabilizing effects of LUCL internal bracing to triceps tendon graft reconstruction in simulated PLRI.

METHODS

Sixteen cadaveric elbows were assigned for either LUCL internal bracing (n = 8) or reconstruction with triceps tendon graft (n = 8). Specimen were mounted and a valgus rotational torque was applied to the ulna to test posterolateral rotatory stability. Posterolateral rotation was measured at 0°, 30°, 60°, 90° and 120° of elbow flexion. Cyclic loading was performed for 1000 cycles at 90° of elbow flexion. Three conditions were compared in each specimen: intact elbow, LUCL and radial collateral ligament (RCL) transected, and then either LUCL internal bracing or reconstruction with triceps tendon graft.

RESULTS

Transection of the LUCL and RCL significantly increased posterolateral rotation in all degrees of elbow flexion compared to the intact condition (P < 0.05). Both LUCL internal bracing and reconstruction restored posterolateral rotatory stability to the native state between 0° and 120° of elbow flexion, with no significant difference in improvement between groups. Similarly, LUCL internal bracing and reconstruction groups showed no significant difference in posterolateral rotation compared to the intact condition during cyclic loading.

CONCLUSIONS

At time zero, both LUCL internal bracing and reconstruction with triceps tendon graft restored posterolateral rotatory stability. As such, this study supports the use of internal bracing as an adjunct to primary ligament repair in subacute PLRI.

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

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

The naked capitellum: a surgeon's guide to intraoperative identification of posterolateral rotatory instability

HYPOTHESIS

This study's purpose was to provide a reproducible way for surgeons to intraoperatively assess the elbow's lateral ulnar collateral ligament origin and determine whether there is posterolateral rotatory instability (PLRI) despite an intact common extensor origin (CEO). We hypothesized that we could re-create clinically relevant disruption of lateral supporting structures despite an intact CEO and illustrate progressive elbow PLRI.

METHODS

The relationship of the lateral capsule to the capitellum articular surface was noted in 8 cadaveric upper extremities. The lateral capsule and extensor origin were sequentially sectioned at 4 stages: intact, release to the lateral epicondyle, release of the posterior capsular insertion, and release of the CEO. Posterior and lateral translation of the radial head (RH) relative to the capitellum was measured with the forearm in extension and supination.

RESULTS

The average specimen age was 78.9 years. The lateral capsule originated within 1 to 2 mm of the capitellum articular surface. Lateral capsular sectioning to the 6-o'clock position of the lateral epicondyle created an unstable elbow with posterior and lateral RH translation. Sequential sectioning of the posterior capsular insertion created significant additional RH translation posteriorly (P < .05). With release of the capsule and the extensor origin, the elbow was grossly unstable.

CONCLUSIONS

The elbow's lateral capsuloligamentous complex plays an important role in preventing PLRI. Larger degrees of elbow laxity are associated with further peel back of the capsuloligamentous complex despite an intact CEO. The surgeon must retract the extensor origin intraoperatively to assess for lateral ulnar collateral ligament and/or lateral capsule disruption to prevent a missed case of PLRI.

Multibody modelling of ligamentous and bony stabilizers in the human elbow

The elbow ligamentous and bony structures play essential roles in the joint stability. Nevertheless, the contribution of different structures to joint stability is not yet clear and a comprehensive experimental investigation into the ligament and osseous constraints changes in relation to joint motions would be uphill and somehow unattainable, due to the impossibility of obtaining all the possible configurations on the same specimen. Therefore, a predictive tool of the joint behavior after the loss of retentive structures would be helpful in designing reconstructive surgeries and in pre-operative planning. In this work, a multibody model consisting of bones and non-linear ligamentous structures is presented and validated through comparison with experimental data. An accurate geometrical model was equipped with non-linear ligaments bundles between optimized origin and insertion points. The joint function was simulated according to maneuvers accomplished in published experimental studies which explored the posteromedial rotatory instability (PMRI) in coronoid and posterior medial collateral ligament (PB) deficient elbows. Moreover, a complete design of experiments (DOE) was explored, investigating the influence of the elbow flexion degree, of the coronoid process and of the medial collateral ligaments (MCL) structures (anterior and posterior bundles) in the elbow joint opening. The implemented computational model accurately predicted the joint behavior with intact and deficient stabilizing structures at each flexion degree, and highlighted the statistically significant influence of the MCL structures (P<0.05) on the elbow stability. The predictive ability of this multibody elbow joint model let foresee that future investigations under different loading scenarios and injured or surgically reconstructed states could be effectively simulated, helping the ligaments reconstruction optimization in terms of bone tunnel localizations and grafts pre-loading.

Level of evidence

V.

[Biomechanical effect of anteromedial coronoid facet fracture and lateral collateral ligament complex injury on posteromedial rotational stability of elbow]

Objective

To investigate the effect of anteromedial coronoid facet fracture and lateral collateral ligament complex (LCLC) injury on the posteromedial rotational stability of the elbow joint.

Methods

The double elbows were obtained from 4 fresh adult male cadaveric specimens. Complete elbow joint (group A, n=8), simple LCLC injury (group B, n=4), simple anteromedial coronoid facet fracture (group C, n=4), and LCLC injury combined with anteromedial coronoid facet fracture (group D, n=8). The torque value was calculated according to the load-displacement curve.

Results

There was no complete dislocation of the elbow during the experiment. The torque values of groups A, B, C, and D were (10.286±0.166), (5.775±0.124), (6.566±0.139), and (3.004±0.063) N·m respectively, showing significant differences between groups ( P<0.05).

Conclusion

Simple LCLC injury, simple anteromedial coronoid facet fracture, and combined both injury will affect the posteromedial rotational stability of the elbow.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effect of Anconeus Muscle Blocking on Elbow Kinematics: Electromyographic, Inertial Sensors and Finite Element Study

The specific contribution of the anconeus muscle to elbow function is still uncertain. This study aimed to investigate the effect on elbow kinematics and kinetics of blocking anconeus using lidocaine. Ten healthy volunteers performed experimental trials involving flexion–extension and supination–pronation movements in horizontal and sagittal planes. Inertial sensors and surface electromyography were used to record elbow kinematics and kinetics and electrical activity from the anconeus, biceps and triceps brachii before and after blocking anconeus. Moreover, a finite element model of the elbow was created to further investigate the contribution of anconeus to elbow kinematics. The electrical activity results from the trials before blocking clearly indicated that activity of anconeus was increased during extension, suggesting that it behaves as an extensor. However, blocking anconeus had no effect on the elbow kinematics and kinetics, including the angular velocity, net torque and power of the joint. The electrical activity of the biceps and triceps brachii did not alter significantly following anconeus blocking. These results suggest that anconeus is a weak extensor, and the relative small contribution of anconeus to extension before blocking was compensated by triceps brachii. The finite element results indicated that anconeus does not contribute significantly to elbow kinematics.