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

Lateral ulnar collateral ligament reconstruction enhancing secondary stabilizers in chronic PLRI of the elbow provides good to excellent clinical results with no recurrent instability

PURPOSE

The adopted treatment for chronic elbow PLRI is lateral ulnar collateral ligament reconstruction. However, the most frequently reported complication after primary reconstruction is recurrent instability - up to 25 %. It was thus hypothesized that enhancing the secondary stabilizers will provide successful results with a lower rate of recurrent instability in comparison to techniques with primary reconstruction only. This study aimed to demonstrate a novel surgical technique involving secondary stabilizers.

METHODS

In this retrospective study of 29 cases with chronic PLRI the mean duration of symptoms was 39.6 ± 4.9 months. The mean age was 47.9 years with mainly male patients. The surgeries were performed by one senior surgeon at a single institution. The Mayo Elbow Performance Score (MEPS) and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH) were recorded.

RESULTS

The mean follow-up was 36.8 ± 7.7 months. The MEPS score improved significantly from 59.8 ± 13.1 to 84.7 ± 7.6 (p < 0.001). 23/29 patients (79.2 %) had converted to good and excellent results (MEPS >75 points). The DASH score improved from 40.8 ± 4.6 to 20.9 ± 7.2 (p < 0.001). The total complication rate was 10.3 % (N = 3). No recurrent instability was recorded in comparison to 12.2 % for primary reconstruction only, as reported in the literature (p < 0.05).

CONCLUSION

Enhancing the secondary stabilizers by utilizing an adjacently located autograft provided good and excellent results with no recurrent instability. This novel surgical procedure is easy to reproduce and provides a safe and reliable alternative in cases of chronic PLRI when compared to techniques with primary reconstruction only.

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.

Biomechanical Stability of Lateral Ulnar Collateral Ligament Reconstruction and Repair of the Elbow: The Role of Ligament Bracing on Gap Formation and Stabilization

BACKGROUND

Augmented (internal braced) lateral ulnar collateral ligament (LUCL) repair has been biomechanically compared with reconstruction techniques in the elbow. However, LUCL repair alone has not yet been compared with augmented repair and reconstruction techniques.

HYPOTHESIS

Internal bracing of LUCL repair would improve time-zero stabilization regarding gap formation, stiffness, and residual torque as compared with repair alone and reconstruction techniques to restore native elbow stability.

STUDY DESIGN

Controlled laboratory study.

METHODS

Overall, 24 cadaveric elbows were used for either internal braced LUCL repair (Repair-IB) or single- and double-strand ligament reconstruction with triceps (Recon-TR) and palmaris longus tendon graft (Recon-PL), respectively. Laxity testing in external rotation was consecutively performed at 90° of elbow flexion on the intact, dissected, and repaired conditions and with the previously assigned techniques. First, intact elbows were loaded to 7.0-N·m external torque to evaluate time-zero ligament rotations at 2.5, 4.0, 5.5, and 7.0 N·m. Rotation-controlled cycling was performed (total of 1000 cycles) for each surgical condition. Gapping, stiffness, and residual torque were analyzed. Finally, these and 8 additional intact elbows underwent torque-to-failure testing (30 deg/min).

RESULTS

The dissected state showed the highest gap formation and lowest peak torques (P < .001). While gap formation of Repair-IB (P < .021) was significantly lower than that of repair without internal bracing at all rotation levels, gaps of Recon-PL were similar to and Recon-TR were significantly higher than those of Repair-IB except for the highest torsion level. Residual peak torques at specific rotation angles between native state and Recon-TR (α_2.5), Recon-PL (α_4.0), and Repair-IB (α_5.5) were similar; all other comparisons were significantly different (P < .027). Torsional stiffness of Repair-IB was significantly higher at all rotation angles measured. Analysis of covariance showed significantly less gap formation over residual peak torques for Repair-IB (P < .001) as compared with all other groups. The native state failure load was significantly higher than Recon-PL and Recon-TR failure loads, with similar stiffness to all other groups.

CONCLUSION

Repair-IB and Recon-PL of the LUCL showed increased rotational stiffness relative to the intact elbow for restoring posterolateral stability to the native state in a cadaveric model. Recon-TR demonstrated lower residual peak torques but provided near-native rotational stiffness.

CLINICAL RELEVANCE

Internal bracing of LUCL repair may reduce suture-tearing effects through tissue and provide sufficient stabilization for healing throughout accelerated and reliable recovery without the need for a tendon graft.

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.

Biomechanical Comparison of Two Fixation Techniques for Lateral Ulnar Collateral Ligament Repair With Ligament Bracing

PURPOSE

Ligament bracing is a technique of suture reinforcement that can be used to augment lateral ulnar collateral ligament repair in the treatment of posterolateral rotatory instability of the elbow, thereby improving early stability of the repair. However, multiple failures of the ulnar anchor during implantation have been documented. We hypothesized that the use of a cortical button for ulnar fixation of the ligament brace would be biomechanically comparable to a suture anchor construct.

METHODS

Sixteen elbows were tested with a materials testing machine. The intact, dissected, and repaired lateral collateral ligament complex was tested with a cyclic varus rotational torque of 0.5-3.5 Nm in 120°, 90°, 60°, and 30° elbow flexion. For the repair, the specimens were randomized into 2 groups: ulnar fixation of the ligament bracing using a suture anchor and ulnar fixation of the ligament bracing using a cortical button. The number of implant failures was documented. A load-to-failure protocol was conducted in 90° elbow flexion.

RESULTS

Load to failure was comparable and was found to be 20.7 Nm in the suture anchor group and 21.8 Nm in the cortical button group. Laxity after ligament bracing did not differ significantly between suture anchor and cortical button fixation. Compared with the native ligament, the laxity was significantly reduced after ligament bracing. The failure mode was slippage of the suture tape through the humeral anchor in all cases. Additionally, the capitellum was damaged in 9 of 16 cases.

CONCLUSIONS

A cortical button for ulnar fixation of the ligament bracing was comparable with a suture anchor fixation with regard to biomechanical properties such as laxity and load to failure.

CLINICAL RELEVANCE

A cortical button fixation is less prone to failure of insertion. This would improve the implantation technique, while clinical results are expected to be comparable.

Autologous triceps tendon graft for LUCL reconstruction of the elbow: clinical outcome after 7.5 years

PURPOSE

The objective of this study was to assess mid- to long-term functional outcomes in patients treated for symptomatic posterolateral instability of the elbow (PLRI) using an autologous ipsilateral triceps tendon as graft.

METHODS

A total of 196 patients were treated with autologous triceps tendon graft for symptomatic PLRI at single orthopedic institution from 2006 to 2013. The surgical treatment contained arthroscopic instability testing, reconstruction of the lateral ulnar collateral ligament (LUCL) and harvesting autologous ipsilateral triceps tendon as graft. The follow-up outcomes included range of motion (ROM), pain measured on a visual analogue scale (VAS), Mayo Elbow Performance Score (MEPS), Oxford Elbow Score (OES) and ultrasound to evaluate the integrity of the refixation of the common extensor.

RESULTS

A total of 178 patients (female: 73; male: 105) were available for follow-up at a mean of 91 months (range 48-144). No patient reported pain at rest; VAS during activity was 1.8 (range 0-5). The ROM decreased slightly compared to preoperative measurements. Flexion decreased significantly from 135.4 to 131.1, though still within the functional arc of motion. All but 13 patients (8.5%) were clinically stable. However, only two patients received a revision of the LUCL reconstruction due to subjective instability. The mean MEPS in the final follow-up was 91.3 (range 73-100). The mean OES was 46.5 (range 39-48). Three patients reported a pain-free clicking of the elbow. No patient complained about donor site morbidity of the ipsilateral triceps tendon. Ultrasound evaluation showed integrity of the common extensors in all patients.

CONCLUSIONS

LUCL reconstruction using the ipsilateral triceps tendon as graft shows good to excellent mid- to long-term results in the treatment of symptomatic posterolateral elbow joint instability with a low re-instability and complication rate.

Biomechanical comparison of lateral collateral ligament reconstruction with and without additional internal bracing using a three-dimensional elbow simulator

BACKGROUND

Although an additional internal bracing significantly increases stability in a repair of the lateral ulnar collateral ligament, it remains unclear whether it also does in reconstruction. Aim of this study was to implement a three-dimensional elbow simulator for testing posterolateral rotatory instability. We hypothesized that (1) reconstruction with and without internal bracing is comparable in biomechanical properties, and (2) there would be higher load-to-failure with internal bracing.

METHODS

Posterolateral rotatory instability was tested by imitating the lateral pivot shift test in 16 elbows. Valgus and supination torques were simultaneously increased stepwise up to 1.2 Nm. Specimens were tested at 30°, 60°, 90°, and 120° elbow flexion with an intact lateral collateral ligament complex, dissected complex, and after reconstruction with or without internal bracing. Outcome measures included joint gapping, laxity, and load to failure.

FINDINGS

With the implemented elbow simulator no significant difference was observed for gapping or laxity between both treatment groups. Comparing treatment and native ligament, gapping was reduced, especially with increased elbow flexion. Laxity was also reduced at some flexion angles. The mean load-to-failure was 8.1 ± 2.7 Nm without and 9.6 ± 3.6 Nm with internal bracing (P = 0.645).

INTERPRETATION

Both treatments were comparable in biomechanical properties but did not fully restore the native state. Although the additional augmentation of the LUCL reconstruction tends to increase the maximum load to failure, this difference was not statistically significant. Still, reconstruction with internal bracing seems to be a reasonable option in selected primary reconstructions. It could also be useful in revision reconstruction.

Suture tape augmentation of the lateral ulnar collateral ligament increases load to failure in simulated posterolateral rotatory instability

PURPOSE

Simple elbow dislocations are accompanied with lateral ulnar collateral ligament ruptures. For persisting instability, surgery is indicated to prevent chronic posterolateral rotatory instability. After lateral collateral ligament (LCL) complex repair the repair is protected by temporary immobilization, limited range of motion and hinged bracing. Internal bracing is an operative alternative augmenting the LCL repair using non-absorbable suture tapes. However, the stability of LCL repair with and without additional augmentation remains unclear. The hypothesis was that LCL repair with additional suture tape augmentation would improve load to failure. Secondary goal of this study was to evaluate different humeral fixation techniques. A humeral fixation using separate anchors for the LCL repair and the augmentation was not expected to provide superior stability compared to using only one single anchor.

METHODS

Twenty-one elbows were tested. A cyclic varus rotational torque of 0.5-3.5 Nm was applied in 90°, 60°, 30°, and 120° elbow flexion to the intact, torn, and repaired LCLs. The specimens were randomized into three groups: repair alone (group I), repair with additional internal bracing using two anchors (group II), repair using one humeral anchor (group III). A load-to-failure protocol was conducted.

RESULTS

Load to failure was significantly higher in groups II (26.6 Nm; P = 0.017) and III (23.18 Nm; P = 0.038) than in group I (12.13 Nm). No significant difference was observed between group II and III. All specimens lost reduction after LCL dissection by a mean of 4.48° ± 4.99° (range 0.66-15.82). The mean reduction gain after repair was 7.21° ± 4.97° (2.70-21.23; mean over reduction, 2.73°). The laxity was comparable between the intact and repaired LCLs (n.s.), except for varus movements at 30° in group II (P = 0.035) and 30° (P = 0.001) and 120° in group III (P = 0.008) with significantly less laxity. Inserting the ulnar suture anchor showed failure in the thread in 10 cases.

CONCLUSION

LCL repair with additional internal bracing yielded higher load to failure than repair alone. Repair with additional internal bracing for the humeral side using one anchor was sufficient. A higher primary stability would facilitate postoperative management and allow immediate functional treatment. Reducing the number of humeral anchors would save costs.

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.

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.

Repair and augmentation of the lateral collateral ligament complex using internal bracing in dislocations and fracture dislocations of the elbow restores stability and allows early rehabilitation

PURPOSE

Most elbow dislocations can be treated conservatively, with surgery indicated in special circumstances. Surgical options, apart from fracture fixation, range from repair or reconstruction of the damaged ligaments to static external fixation, usually entailing either a long period of immobilization followed by carefully monitored initiation of movement or dynamic external fixation. In general, no consensus regarding surgical treatment has been reached. A new method of open ligament repair and augmentation of the lateral ulnar collateral ligament using a non-absorbable suture tape in cases of acute and subacute elbow instability following dislocations has been described here, which allows an early, brace-free initiation of the full range of motion. This is the first description of the technique of internal bracing of the lateral elbow with preliminary patient outcome parameters for acute treatment of posterolateral rotatory instability.

METHODS

Seventeen patients (14 males and 3 females) with acute or subacute posterolateral elbow instability as a result of dislocation or fracture dislocation were treated in our centre (Sporthopaedicum, Straubing, Regensburg, Germany) from 2014 to 2015 with open LUCL re-fixation and non-absorbable suture tape augmentation. The elbows were actively mobilized immediately after the operation and a maximum bracing period of 3 days.

RESULTS

At 10 month median follow-up, none of the patients showed clinically apparent signs of instability or suffered subluxation or re-dislocation. One patient required re-operation for heterotopic ossification. The median range of motion was from 10° (0-40) to 130° (90-50) and median Oxford, Mayo Elbow Performance score, Simple Elbow Value, and DASH Scores were 41(29-48), 100 (70-100), 83% (60-95), and 18.5 (1.6-66), respectively. All patients reported a complete return to pre-injury level of activity.

CONCLUSION

Augmentation with a non-absorbable suture tape acting as an 'Internal Brace' following an elbow dislocation is a safe adjunct to primary ligament repair and may allow the early mobilization and recovery of elbow stability and range of motion.

LEVEL OF EVIDENCE

IV.

[Chronic ligamentous instability of the elbow]

BACKGROUND

Chronic ligamentous instability of the elbow is an important pathology as it is accompanied with pronounced dysfunction. Moreover, it represents an established risk factor for the development of osteoarthritis. Posterolateral rotatory instability (PLRI) caused by insufficiency of the lateral collateral ligament (LCL) is the most common type of chronic elbow instability and is usually a sequel of traumatic elbow dislocation. Chronic overload can lead to insufficiency of the ulnar collateral ligament (UCL) with subsequent valgus instability, especially in overhead athletes.

DIAGNOSTICS

Subjective instability and recurrent elbow dislocations are not always the main symptoms but elbow instability is instead often characterized by pain and secondary joint stiffness. Many clinical tests are available yet eliciting them can be difficult and inconclusive. A "drop sign" on lateral radiographs as well as the detection of collateral ligament injuries and joint incongruity on MRI scans can support the suspected diagnosis. In some cases, instability can only be verified by diagnostic arthroscopy.

TREATMENT

Reconstruction of the lateral ulnar collateral ligament (LUCL) for treatment of PLRI generally leads to good clinical results, yet recurrent instability remains an issue and has been reported in 8 % of cases. UCL reconstruction for chronic valgus instability leads to a return-to-sports rate of about 86 % in the overhead athlete. Ulnar neuropathy, which is seen in approximately 6 % of patients, represents the most common complication. On the rare occasion of multidirectional instability, the box-loop technique can be used for simultaneous reconstruction of the LUCL and UCL with a circumferential graft. 15 cases with promising results have been reported in literature thus far.

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.

The circumferential graft technique for treatment of multidirectional elbow instability: a comparative biomechanical evaluation

BACKGROUND

Ligament reconstruction with a circumferential graft represents an innovative technique for treatment of multidirectional elbow instability. This biomechanical study compared the stability of the intact elbow joint with the circumferential graft technique and the conventional technique.

METHODS

Seven fresh frozen cadaveric elbows were evaluated for stability against valgus and varus/posterolateral rotatory forces (3 Nm) over the full range of motion. Primary stability was determined for intact specimens, after sectioning of the collateral ligaments, after applying the circumferential graft technique (box-loop), and after conventional collateral ligament reconstruction. Cyclic loading (1000 cycles) was performed to assess joint stability and stiffness of the native ligaments and the tendon grafts.

RESULTS

Primary stability of both reconstruction techniques was equal to the native specimens (P = .17-.91). Sectioning of the collateral ligaments significantly increased joint instability (P < .001). The reconstruction techniques provided equal stability after 1000 cycles (P = .78). Both were inferior to the intact specimens (P = .02). Cyclic loading caused a significantly lower increase in stiffness of the native ligaments compared with the tendon grafts of either reconstruction technique (P = .001-.008). Significantly better graft stiffness was retained with the circumferential graft technique compared with conventional reconstruction (P = .04).

CONCLUSION

Neither reconstruction technique fully reproduces the biomechanical profile of the native collateral ligaments. The circumferential graft technique seems to resist cyclic loading slightly better than the conventional reconstruction technique, yet both reconstruction techniques provide comparable stability.