Rehabilitation of the medial collateral ligament-deficient elbow: an in vitro biomechanical study

SpasticSim: a synthetic data generation method for upper limb spasticity modelling in neurorehabilitation

In neurorehabilitation, assessment of functional problems is essential to define optimal rehabilitation treatments. Usually, this assessment process requires distinguishing between impaired and non-impaired behavior of limbs. One of the common muscle motor disorders affecting limbs is spasticity, which is complicated to quantify objectively due to the complex nature of motor control. Thus, the lack of heterogeneous samples of patients constituting an acceptable amount of data is an obstacle which is relevant to understanding the behavior of spasticity and, consequently, quantifying it. In this article, we use the 3D creation suite Blender combined with the MBLab add-on to generate synthetic samples of human body models, aiming to be as sufficiently representative as possible to real human samples. Exporting these samples to OpenSim and performing four specific upper limb movements, we analyze the muscle behavior by simulating the six degrees of spasticity contemplated by the Modified Ashworth Scale (MAS). The complete dataset of patients and movements is open-source and available for future research. This approach advocates the potential to generate synthetic data for testing and validating musculoskeletal models.

Choice of treatments of the coronal shear fractures of the humerus. A national survey of Italian AO members

INTRODUCTION

Coronal shear fractures of the distal humerus are uncommon injuries representing 6% of distal humeral fractures. There is no univocal consensus about the correct management of this type of fracture. A national survey was conducted to gain more insight into the current classification, diagnosis and treatment of coronal shear fractures in Italy.

MATERIALS AND METHODS

A postal survey was sent to all AO Italian members including residency orthopaedic surgeons. The survey consisted of general questions about personal experience in the management of these fractures: types of classification systems used, surgical approaches, treatment options and rehabilitation programs.

RESULTS

114 orthopaedic surgeons answered a 13-items questionnaire. The most used classification system was AO/OTA (72,8%). Independent screws and if necessary plates were the most answered regarding surgical treatment (81,6%). The most encountered post-surgical complication was stiffening of the elbow (81,6%).

CONCLUSION

An algorithm of treatment has been proposed. To better classify coronal shear fractures, the authors recommended the integration of two classification systems: AO and Dubberley classifications. In the case of posterior wall comminution, a Kocher extensile approach is recommended, otherwise, if a posterior wall is intact, Kocher or Kaplan approach can be used. The posterior transolecranic approach can be reserved to Dubberley type III or AO 13B3.3. The best treatment choice is represented by independent screws and plates placed according to fracture patterns while arthroplasty is indicated when a stable ORIF is not possible. Mobilization is postponed for about 2 weeks.

Testing of Novel Total Elbow Prostheses Using Active Motion Experimental Setup

PURPOSE

The goal of this study was to test a novel uncemented and unconstrained total elbow arthroplasty (Kaufmann total elbow) design that is stabilized through a ligament reconstruction.

METHODS

We quantified the implant stability after 25,000 cycles, which represents the time between implantation and when ligament and bone healing has occurred. We used an active motion experimental setup that applies tendon loads via pneumatic cylinders and reproduces the forearm-originating dynamic stabilizers of the elbow. The novel total elbow arthroplasty was actuated for 5,000 full flexion-extension cycles at 5 different shoulder positions. Four Sawbones and 4 cadaver elbows were employed. Angular laxity and implant stability were recorded prior to testing and after each 5,000-loading cycle.

RESULTS

Four Sawbones and 4 cadaver elbows were implanted with the uncemented total elbow arthroplasty and did not demonstrate fixation failure or substantial laxity after 25,000 cycles of loading imparted at different shoulder positions.

CONCLUSIONS

Our findings demonstrate that the Kaufmann total elbow replacement implanted into cadaver and Sawbones specimens did not exhibit fixation failure or excessive laxity after 25,000 cycles.

CLINICAL RELEVANCE

An uncemented, nonmechanically linked total elbow arthroplasty that gains component fixation using intramedullary screws and employs a ligament reconstruction to stabilize the elbow has the potential to be a valuable management option, particularly in younger patients.

Overhead arm positioning in the rehabilitation of elbow dislocations: An in vitro biomechanical study

STUDY DESIGN

In vitro biomechanical study.

INTRODUCTION

Elbow stiffness is a common complication following elbow dislocation. Overhead exercises have been proposed to initiate early motion to reduce stiffness through employing gravity to stabilize the elbow. The implications of this position with regard to elbow kinematics after dislocation have not been reported.

PURPOSE OF THE STUDY

To determine the influence of the overhead position on elbow stability following combined medial and lateral collateral ligament (MCL and LCL) injuries.

METHODS

Passive and simulated active extension were performed on 11 cadaveric elbows with the arm in the overhead, dependent, and horizontal positions and with the forearm in pronation, neutral, and supination. Internal-external rotation (IER) and varus-valgus angulation (VVA) of the ulnohumeral joint were assessed for the intact elbow and after simulated MCL-LCL injury. Repeated-measures analyses of variance were conducted to analyze the effects of elbow state, arm position, forearm rotation, and extension angle.

RESULTS

During passive extension with the arm overhead, the pronated position resulted in more internal rotation than supination (-2.6 ± 0.7°, P = .03). There was no effect of forearm rotation on VVA. The overhead position increased internal rotation relative to the dependent position when the forearm was neutral (-8.5 ± 2.5°, P = .04) and relative to the horizontal position when the forearm was supinated (-12.7 ± 2.2°, P= .02). During active extension, pronation increased valgus angle compared to the neutral (+1.2 ± 0.3°, P= .04) and supinated (+1.5 ± 0.4°, P= .03) positions, but did not affect IER. There was no difference between active and passive motion with the arm overhead (P > .05).

DISCUSSION

Movement of the injured elbow in the overhead position most closely replicated kinematics of the intact elbow compared to the other arm positions.

CONCLUSIONS

Overhead elbow extension results in similar kinematics between an intact elbow and an elbow with MCL and LCL tears. As such, therapists might consider early motion in this position to reduce the risk of elbow stiffness after dislocation.

Coronal Shear Fractures of the Distal Humerus

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

Treatment of elbow instability: state of the art

The elbow is a congruent joint with a high degree of inherent stability, provided by osseous and soft-tissue constraints; however, when substantial lesions of these stabilising structures happen, instability of the elbow occurs. Significant improvements in surgical elbow instability diagnosis and treatment have been recently introduced both for acute and chronic cases. Specific stress tests, recently introduced in the clinical practice, and different imaging techniques, both static and dynamic, allow assessment of the elbow stabilisers and detection of the instability direction and mechanism even in subtle forms. Many surgical techniques have been standardised and surgical instruments and devices, specifically dedicated to elbow instability treatment, have been developed. Specific rehabilitation protocols have been designed to protect the healing of the elbow stabilisers while minimising elbow stiffness. However, despite the progress, surgical treatments can be challenging even for expert surgeons and the rate of persistent instability, post-traumatic arthritis, stiffness and pain can be still high especially in most demanding cases. The biology of the soft-tissue healing remains one of the most important aspects for future investigation. If future research will help to understand, correct or modulate the biological response of soft-tissue healing, our confidence in elbow instability management and the reproducibility of our treatment will tremendously improve. In this paper, the state of the art of the current knowledge of elbow instability is presented, specifically focusing on modern surgical techniques used to solve instability, with repair or reconstruction of the damaged elbow stabilisers.

Rehabilitation of Elbow Instability

The elbow is the second most commonly dislocated major joint in adults with estimated incidence of 5 dislocations per 100,000 persons per year. A comprehensive understanding of elbow anatomy and biomechanics is essential to optimize rehabilitation of elbow injuries. This allows for implementation of a systematic therapy program that encourages early mobilization within a safe arc of motion while maintaining joint stability. To optimize outcomes, close communication between surgeon and therapist is necessary to allow for implementation of an individualized rehabilitation program. This article reviews key concepts that enable the clinician to apply an evidence-informed approach when managing elbow instability.

The Effectiveness of a Hinged Elbow Orthosis in Medial Collateral Ligament Injuries: An In Vitro Biomechanical Study

BACKGROUND

Medial collateral ligament (MCL) injuries are common after elbow trauma and in overhead throwing athletes. A hinged elbow orthosis (HEO) is often used to protect the elbow from valgus stress early after injury and during early return to play. However, there is minimal evidence regarding the efficacy of these orthoses in controlling instability and their influence on long-term clinical outcomes.

PURPOSE

(1) To quantify the effect of an HEO on elbow stability after simulated MCL injury. (2) To determine whether arm position, forearm rotation, and muscle activation influence the effectiveness of an HEO.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seven cadaveric upper extremity specimens were tested in a custom simulator that enabled elbow motion via computer-controlled actuators and motors attached to relevant tendons. Specimens were examined in 2 arm positions (dependent, valgus) and 2 forearm positions (pronation, supination) during passive and simulated active elbow flexion while unbraced and then while braced with an HEO. Testing was performed in intact elbows and repeated after simulated MCL injury. An electromagnetic tracking device measured valgus angulation as an indicator of elbow stability.

RESULTS

When the arm was dependent, the HEO increased valgus angle with the forearm in pronation (+1.0°± 0.2°, P = .003) and supination (+1.5°± 0.0°, P = .006) during active motion. It had no significant effect on elbow stability during passive motion. In the valgus position, the HEO had no effect on elbow stability during passive or active motion in pronation and supination. With the arm in the valgus position with the HEO, muscle activation reduced instability during pronation (-10.3°± 2.5°, P = .006) but not supination (P = .61).

CONCLUSION

In this in vitro study, this HEO did not enhance mechanical stability when the arm was in the valgus and dependent positions after MCL injury.

CLINICAL RELEVANCE

After MCL injury, an HEO likely does not provide mechanical elbow stability during rehabilitative exercises or when the elbow is subjected to valgus stress such as occurs during throwing.

The effect of implant linking and ligament integrity on humeral loading of a convertible total elbow arthroplasty

BACKGROUND

Both unlinked and linked total elbow arthroplasty (TEA) implants have been employed with no consensus as to the optimal design. The present study aimed to evaluate the effect of collateral ligament integrity and implant linkage on wear-inducing loads in a convertible TEA.

METHODS

Eight fresh frozen upper extremities were tested in an elbow motion simulator. A convertible TEA with an instrumented humeral stem was inserted using computer navigation. Elbow kinematics and humeral loading were recorded with the TEA both linked and unlinked. The collateral ligaments were then sectioned and testing was repeated.

RESULTS

In the dependent position, there was no effect of implant linkage or ligament sectioning on humeral loading. Humeral loading was significantly greater following sectioning of the collateral ligaments but not after linking the TEA with the arm in the valgus position. Humeral loading was significantly greater after linking the TEA but not after sectioning of the collateral ligaments and with the arm in the varus position.

CONCLUSIONS

Collateral ligament integrity reduces wear-inducing loads for both an unlinked and linked TEA. Linkage of a convertible TEA increases humeral loading, which may have detrimental effects on implant longevity.

Medial Collateral Ligament Deficiency of the Elbow Joint: A Computational Approach

Computational elbow joint models, capable of simulating medial collateral ligament deficiency, can be extremely valuable tools for surgical planning and refinement of therapeutic strategies. The objective of this study was to investigate the effects of varying levels of medial collateral ligament deficiency on elbow joint stability using subject-specific computational models. Two elbow joint models were placed at the pronated forearm position and passively flexed by applying a vertical downward motion on humeral head. The models included three-dimensional bone geometries, multiple ligament bundles wrapped around the joint, and the discretized cartilage representation. Four different ligament conditions were simulated: All intact ligaments, isolated medial collateral ligament (MCL) anterior bundle deficiency, isolated MCL posterior bundle deficiency, and complete MCL deficiency. Minimal kinematic differences were observed for isolated anterior and posterior bundle deficient elbows. However, sectioning the entire MCL resulted in significant kinematic differences and induced substantial elbow instability. Joint contact areas were nearly similar for the intact and isolated posterior bundle deficiency. Minor differences were observed for the isolated anterior bundle deficiency, and major differences were observed for the entire MCL deficiency. Complete elbow dislocations were not observed for any ligament deficiency level. As expected, during isolated anterior bundle deficiency, the remaining posterior bundle experiences higher load and vice versa. Overall, the results indicate that either MCL anterior or posterior bundle can provide anterior elbow stability, but the anterior bundle has a somewhat bigger influence on joint kinematics and contact characteristics than posterior one. A study with a larger sample size could help to strengthen the conclusion and statistical significant.

Valgus instability of the elbow: acute and chronic form

There has been an increase in thrower-specific elbow injuries in recent years. High valgus stresses during the late cocking and acceleration phases of throwing need to be compensated by the flexor pronator muscles as these can exceed the tensile strength of the medial collateral ligament complex. Prevention of injuries is the priority, with a focus on strengthening, reducing throwing frequency, decreasing force, and promoting a technique. The spectrum of thrower injuries ranges from a simple sprain to complete failure of the valgus stabilizing factors. The medial collateral ligament can stretch, leading to posteromedial impingement and radiocapitellar compression forces. This in turn can result in arthrosis and the formation of osteophytes. Ligament failure may eventually occur, making it impossible for the athlete to continue their throwing activities. The outcome of conservative treatment with strengthening, improvement of technique, and relative rest is often disappointing. Direct repair may no longer be possible in these acute-on-chronic injuries and a reconstruction with a tendon graft may be necessary.

Applying a Hybrid Experimental-Computational Technique to Study Elbow Joint Ligamentous Stabilizers

Much of our understanding of the role of elbow ligaments to overall joint biomechanics has been developed through in vitro cadaver studies using joint motion simulators. The principle of superposition can be used to indirectly compute the force contributions of ligaments during prescribed motions. Previous studies have analyzed the contribution of different soft tissue structures to the stability of human elbow joints, but have limitations in evaluating the loads sustained by those tissues. This paper introduces a unique, hybrid experimental-computational technique for measuring and simulating the biomechanical contributions of ligaments to elbow joint kinematics and stability. in vitro testing of cadaveric joints is enhanced by the incorporation of fully parametric virtual ligaments, which are used in place of the native joint stabilizers to characterize the contribution of elbow ligaments during simple flexion–extension (FE) motions using the principle of superposition. Our results support previously reported findings that the anterior medial collateral ligament (AMCL) and the radial collateral ligament (RCL) are the primary soft tissue stabilizers for the elbow joint. Tuned virtual ligaments employed in this study were able to restore the kinematics and laxity of elbows to within 2 deg of native joint behavior. The hybrid framework presented in this study demonstrates promising capabilities in measuring the biomechanical contribution of ligamentous structures to joint stability.

In Vitro Kinematic Assessment of a Hinged Elbow Orthosis Following Lateral Collateral Ligament Injury

PURPOSE

Elbow lateral collateral ligament injuries (LCLI) are often managed with protected mobilization using a hinged elbow orthosis (HEO). The objective of this investigation was to determine the effectiveness of an HEO in stabilizing the elbow following LCLI.

METHODS

Seven fresh-frozen cadaveric upper extremity specimens were studied using a custom simulator that enabled elbow motion via computer-controlled actuators and servomotors attached to relevant tendons. Specimens were examined in 4 arm positions (dependent, overhead, horizontal, and varus) and 2 forearm positions (pronation and supination) during both passive and simulated active elbow extension. Specimens were examined before and after simulated LCLI, and then with the addition of an HEO. The lateral collateral ligament, common extensor origin, and lateral elbow capsule were sectioned in the injury model. An electromagnetic tracking system measured ulnohumeral kinematics.

RESULTS

The orthosis did not change elbow stability in any arm position during active motion. Muscle activation and forearm pronation enhanced stability in the dependent, horizontal, and varus positions while the HEO was applied.

CONCLUSIONS

This HEO does not improve the in vitro stability of the elbow following simulated LCLI.

CLINICAL RELEVANCE

An HEO may be safe to use during active motion, but when a patient is not activating the muscles normally (ie, owing to fatigue or cognitive impairment) and the arm is in positions in which the weight of the orthosis might increase joint distraction, an HEO may be harmful. If an HEO is used, the forearm should be braced in pronation following LCLI.

Simple elbow dislocation

The elbow is the second most commonly dislocated major joint in adults. Good long-term outcomes have been reported after non-operative management; however, a small proportion (<10%) of patients have a poor outcome and some do require surgical intervention. A review of the anatomy, pathoanatomy, management and outcomes of simple elbow dislocations is presented. Emphasis is placed on emerging concepts regarding the soft tissue injury, the stabilising structures that are injured, the sequence and mechanism of injury and the relationship to elbow stability. The benefits of nonsurgical and surgical management are discussed and a treatment algorithm based on the pathoanatomy is proposed.

Treatment of Radial Head Fractures with a Modular Metallic Radial Head Replacement

Introduction

Radial head arthroplasty with a smooth-stemmed metallic modular implant is a reliable treatment option for patients with acute unreconstructible radial head fractures, and good clinical outcomes may be expected beyond 5 years of follow-up (Video 1).

Indications & Contraindications

Step 1 Preoperative Planning

Obtain a careful history and perform a physical examination along with appropriate imaging to facilitate appropriate treatment decisions.

Step 2 Operating Room Setup and Patient Positioning

Perform proper operating room setup and patient positioning, as they are required to gain access to all affected structures around the elbow in a safe and efficient manner.

Step 3 Approach

Make a midline posterior skin incision with development of a full-thickness lateral fasciocutaneous flap or use a direct lateral incision; the deep interval is determined on the basis of the integrity of the LCL.

Step 4 Radial Head Excision

Remove and preserve all fragments of the radial head for implant sizing.

Step 5 Implant Sizing

Implant a prosthesis that closely replicates the dimensions of the native radial head, which is the primary goal of the procedure.

Step 6 Stem Broaching

Sequentially broach the canal until good cortical contact is achieved and undersize the definitive stem by 1 mm to allow implant movement within the canal and appropriate articulation with the capitellum.

Step 7 Insertion of Trial Components and Final Radial Head Implant

With the selected trial in place, assess the radial head diameter, height, and articular congruency.

Step 8 Closure and Repair of the LCL

Ensure proper repair of the LCL as it is essential to maintaining or restoring elbow stability.

Step 9 Postoperative Protocol

Postoperative rehabilitation depends on the status of the collateral ligaments.

Results

In a review of the cases of 55 patients at a mean follow-up of 8 years after radial head arthroplasty with a smooth-stemmed modular metallic prosthesis, Marsh et al.⁹.

Pitfalls & Challenges

In-Vitro Quantification of Medial Collateral Ligament Tension in the Elbow

The anterior bundle of the medial collateral ligament (AMCL) of the elbow is commonly injured in patients with elbow dislocations and in throwing athletes. This in-vitro study quantified tension in the native AMCL throughout elbow flexion for different arm positions. We conducted passive and simulated active elbow flexion in seven fresh-frozen cadaveric upper extremities using an established motion simulator. Motions were performed in the valgus and vertical positions from 20-120° while measuring AMCL tension using a custom transducer. Average AMCL tension was higher in the valgus compared to vertical position for both active (p = 0.03) and passive (p = 0.01) motion. Peak AMCL tension was higher in the valgus position for active (p = 0.02) and passive (p = 0.01) motion. There was no significant difference in AMCL tension between active and passive motion in the valgus (p = 0.15) or vertical (p = 0.39) positions. In the valgus position, tension increased with elbow flexion from 20-70° for both active (p = 0.04) and passive (p = 0.02) motion, but not from 70-120°. This in-vitro study demonstrated that AMCL tension increases with elbow flexion, and is greater in the valgus position relative to the vertical position. This information has important implications to the desired target strength of repair and reconstruction techniques.

Current concepts in the management of radial head fractures

Fracture of the radial head is a common injury. Over the last decades, the radial head is increasingly recognized as an important stabilizer of the elbow. In order to maintain stability of the injured elbow, goals of treatment of radial head fractures have become more and more towards restoring function and stability of the elbow. As treatment strategies have changed over the years, with an increasing amount of literature on this subject, the purpose of this article was to provide an overview of current concepts of the management of radial head fractures.

Capitellar and Trochlear Fractures

Fractures of the capitellum and trochlea account for a small proportion of elbow trauma. Clinicians need to be vigilant in their assessment as they are commonly associated with other injuries about the elbow. To optimize outcomes, the goals of management include a stable, anatomic reduction and early range of motion. Closed reduction of noncomminuted fractures may be successful but requires close follow-up. Open reduction and internal fixation is the preferred management of displaced capitellum-trochlear fractures. Elbow stiffness is the most commonly reported complication in operatively treated fractures. Arthroscopic-assisted reduction and internal fixation and arthroplasty are evolving management options.

Simple Elbow Dislocation

Simple elbow dislocation refers to those elbow dislocations that do not involve an osseous injury. A complex elbow dislocation refers to an elbow that has dislocated with an osseous injury. Most simple elbow dislocations are treated nonoperatively. Understanding the importance of the soft tissue injury following a simple elbow dislocation is a key to being successful with treatment.

Management of distal humeral coronal shear fractures

Coronal shear fractures of the distal humerus are rare, complex fractures that can be technically challenging to manage. They usually result from a low-energy fall and direct compression of the distal humerus by the radial head in a hyper-extended or semi-flexed elbow or from spontaneous reduction of a posterolateral subluxation or dislocation. Due to the small number of soft tissue attachments at this site, almost all of these fractures are displaced. The incidence of distal humeral coronal shear fractures is higher among women because of the higher rate of osteoporosis in women and the difference in carrying angle between men and women. Distal humeral coronal shear fractures may occur in isolation, may be part of a complex elbow injury, or may be associated with injuries proximal or distal to the elbow. An associated lateral collateral ligament injury is seen in up to 40% and an associated radial head fracture is seen in up to 30% of these fractures. Given the complex nature of distal humeral coronal shear fractures, there is preference for operative management. Operative fixation leads to stable anatomic reduction, restores articular congruity, and allows initiation of early range-of-motion movements in the majority of cases. Several surgical exposure and fixation techniques are available to reconstruct the articular surface following distal humeral coronal shear fractures. The lateral extensile approach and fixation with countersunk headless compression screws placed in an anterior-to-posterior fashion are commonly used. We have found a two-incision approach (direct anterior and lateral) that results in less soft tissue dissection and better outcomes than the lateral extensile approach in our experience. Stiffness, pain, articular incongruity, arthritis, and ulnohumeral instability may result if reduction is non-anatomic or if fixation fails.

Three-dimensional in vivo kinematics during elbow flexion in patients with lateral humeral condyle nonunion by an image-matching technique

BACKGROUND

An established nonunion of the lateral humeral condyle often reveals elbow instability and accompanying pain. The purpose of this study was to obtain 3-dimensional and quantitative information about the pathologic kinematics of the ulnohumeral joint with nonunion of the lateral humeral condyle by an in vivo and 3-dimensional motion analysis.

METHODS

Magnetic resonance or computed tomography images of the elbows of 14 patients were acquired in 3 positions between full extension and full flexion. We evaluated ulnohumeral motion and calculated the change in the length of the medial collateral ligament during elbow flexion.

RESULTS

Ulnohumeral motion was associated with an excessive lateral shift of ulnar movement. In addition, the distal part of the ulna was rotated in the varus direction, leading to a decrease in the carrying angle. The ulna tended to exhibit internal rotation from full extension to 90° of flexion of the elbow. With further flexion, the ulna rotated externally and returned to its neutral position. Furthermore, the length of the medial collateral ligament increased with an increase in the elbow flexion angle.

CONCLUSION

Patients with lateral humeral condyle nonunion showed excessive lateral shift of the ulna and ulnar axial rotation. Also, the lateral shift caused an osseous protrusion of the medial trochlea, leading to elongation of the medial collateral ligament.

Functional differences between anatomical regions of the anconeus muscle in humans

This study sought to resolve a longstanding debate of the function of anconeus. Intramuscular and surface electromyography electrodes recorded muscle activity from two regions of anconeus and from typical elbow flexion and extension muscles. Eleven participants performed pronation-supination around the medial and lateral axes of the forearm, elbow flexion-extension in pronation, supination and neutral positions of the forearm, and gripping. Maximal voluntary contractions (MVC) and submaximal (10% MVC) force-matching tasks were completed. Activity varied between longitudinal (AL) and transverse (AT) segments of anconeus. Although both muscle regions were active across multiple directions (including opposing directions), AL was more active during pronation than supination, whereas AT showed no such difference. During pronation, activity of AL and AT was greatest about the lateral forearm axis. AT was more active during elbow extension with the forearm in pronation, whereas AL did not differ between pronated and neutral forearm alignment. These findings are consistent with the proposal that AL makes a contribution to control of abduction of the ulna during forearm pronation. Different effects of forearm position on AL and AT activity during elbow extension may be explained by the anatomical differences between the regions. These data suggest anconeus performs multiple functions at the elbow and forearm and this varies between anatomically distinct regions of the muscle.

Rehabilitation of the medial- and lateral collateral ligament-deficient elbow: an in vitro biomechanical study

DESIGN

In vitro biomechanical research using an elbow motion simulator.

INTRODUCTION

The optimal rehabilitation of elbow dislocations with medial collateral ligament (MCL) and lateral collateral ligament (LCL) injuries has not been defined.

PURPOSE

To determine a safe rehabilitation protocol for elbow dislocations with MCL and LCL injuries.

METHODS

Eight cadaveric elbows underwent simulated active and passive motions with the arm in multiple orientations. Varus-valgus angulation and internal-external rotation of the ulna relative to the humerus were quantified for the intact joint and with injured MCL and LCL.

RESULTS

Active motion with injured MCL and LCL in the horizontal and vertical orientations resulted in kinematics similar to the intact elbow, whereas passive motion resulted in significant kinematic alterations. Marked elbow instability was noted in the varus and valgus orientations using both active and passive motion.

CONCLUSIONS

Elbows with MCL and LCL injuries should be rehabilitated using active motion in the horizontal or vertical orientations.

LEVEL OF EVIDENCE

Basic science research.

Fractures of the radial head and neck

The majority of simple fractures of the radial head are stable, even when displaced 2 mm. Articular fragmentation and comminution can be seen in stable fracture patterns and are not absolute indications for operative treatment. Preservation and/or restoration of radiocapitellar contact is critical to coronal plane and longitudinal stability of the elbow and forearm. Partial and complete articular fractures of the radial head should be differentiated. Important fracture characteristics impacting treatment include fragment number, fragment size (percentage of articular disc), fragment comminution, fragment stability, displacement and corresponding block to motion, osteopenia, articular impaction, radiocapitellar malalignment, and radial neck and metaphyseal comminution and/or bone loss. Open reduction and internal fixation of displaced radial head fractures should only be attempted when anatomic reduction, restoration of articular congruity, and initiation of early motion can be achieved. If these goals are not obtainable, open reduction and internal fixation may lead to early fixation failure, nonunion, and loss of elbow and forearm motion and stability. Radial head replacement is preferred for displaced radial head fractures with more than three fragments, unstable partial articular fractures in which stable fixation cannot be achieved, and fractures occurring in association with complex elbow injury patterns if stable fixation cannot be ensured.

The influence of gravity on the unstable elbow

BACKGROUND

Safely permitting early range of motion after a destabilizing injury to the elbow is believed to optimize return of function. However, the range-of-motion exercises must be balanced against the risk of re-dislocation or subluxation. The goal of this study was to describe the position of the upper limb that permitted the greatest motion while minimizing the risk of re-dislocation or subluxation.

METHODS

Seven cadaveric elbows were affixed with a 3-dimensional motion capture system. Ulnohumeral distraction was recorded at flexion angles from 10° to 90° for intact, approach only (sham procedure), and LCL-sectioned. Ulnohumeral separation was recorded in 3 distinct positions of the upper limb that are frequently used in a clinical setting: 1) trunk seated upright with arm at the side; 2) trunk seated upright with elbow in hinged-brace; and 3) trunk supine with shoulder flexed and internally rotated - "gravity-assisted overhead motion" protocol.

RESULTS

A significant ulnohumeral distraction difference was found between the supine and the upright protocols. Upon direct comparison, 104% more displacement occurred across the ulnohumeral joint in the upright LCL-sectioned condition compared to the supine LCL-sectioned condition (P = .001). The greatest ulnohumeral distraction occurred in the seated upright range of motion with a hinged elbow brace (range, 2.5-5.6 mm).

CONCLUSION

The overhead motion protocol is a safe protocol for unstable elbows. The supine position results in the least amount of ulnohumeral distraction across flexion angles from 10° to 90°. The upright protocols, especially with the hinged elbow brace, exhibited ulnohumeral distraction that may result in dislocation.

Radial head fractures

Fractures of the radial head are the most common fractures in the elbow, and they frequently have associated ligamentous, cartilaginous, or other bony injuries. Clinical assessment and radiological investigation allow for accurate diagnosis and the formulation of a management plan. Undisplaced or minimally displaced fractures with no rotational block to motion can be treated nonoperatively with excellent results expected. The minimum amount of displacement in a partial articular radial head fracture required for open reduction and internal fixation to provide a superior outcome to nonoperative management is still unknown. Medium-term data suggest that patients with comminuted radial head fractures do well with radial head replacement.

Rehabilitation considerations in the management of terrible triad injury to the elbow

An elbow dislocation associated with a radial head and coronoid fractures is termed a terrible triad. This injury almost always renders the elbow unstable requiring surgical intervention. The primary goal of surgery is to stabilize the elbow to permit early motion to prevent stiffness. Recent literature has improved our understanding of elbow anatomy and biomechanics as well as the pathoanatomy of this injury. This article reviews key concepts that will allow the surgeon and therapist to apply an systematic rehabilitation approach when managing such injuries.

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.

Results of terrible triads in the elbow: the advantage of primary restoration of medial structure

BACKGROUND

The purpose of this study was to report the clinical and radiological outcomes and surgical strategy for terrible triad injury of the elbow. We hypothesized that the outcomes of this type of injury would be satisfactory if the medial structure was routinely restored at the same time as the repair of the lateral structure.

METHODS

We retrospectively reviewed the results of this treatment performed in 13 elbows with terrible triads. Our surgical protocol included fixation or replacement of the radial head and repair of the ruptured lateral ulnar collateral ligament through the lateral traumatic window. In all cases, simultaneous fixation of the coronoid and repair of the common flexor muscle were performed through the medial traumatic window. In eight patients with medial collateral ligament injury, the ligament was always repaired. The follow-up period ranged from 18 to 41 months (mean, 25 months).

RESULTS

The flexion-extension arc of the elbow averaged 128° and forearm rotation averaged 134.6°. The mean Mayo elbow performance score was 95 points (range, 85 to 100), which corresponded to ten excellent results, and three good results. Concentric stability was restored to all cases. As postoperative complications, one patient had ulnar nerve neuropathy.

CONCLUSIONS

The present operative procedures restoring all damaged lateral and medial structures through the lateral and the medial windows provided satisfactory clinical and radiological outcomes and are recommended for patients with terrible triad injury.

Defining safe rehabilitation for ulnar collateral ligament reconstruction of the elbow: a biomechanical study

BACKGROUND

Ulnar collateral ligament reconstruction of the elbow using a variety of techniques has been successful in enabling overhead athletes with ulnar collateral ligament insufficiency to return to competition. Most current postoperative rehabilitation programs begin with a period of motion restriction, including limiting elbow extension, that is followed by a transition from elbow strengthening to an interval throwing program, to competition. Motion restrictions early in the postoperative period may increase the risk for contractures. There is limited information to support current motion restrictions.

PURPOSE

(1) To determine strain on the reconstructed ulnar collateral ligament during a rehabilitation protocol that includes passive range of motion, isometric muscle contraction, and varus and valgus torques. (2) To develop guidelines for a safe initial rehabilitation protocol.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight cadaveric elbows underwent ulnar collateral ligament reconstruction with the docking technique using a gracilis tendon graft. Differential variable reluctance transducers on the anterior and posterior bands of the reconstructed anterior bundle of the ulnar collateral ligament were used to measure strain, while an optical motion tracking system monitored elbow motion. Strain was measured in the following 3 settings: passive range of motion, 22.2 N isometric flexion and extension contractions, and 3.34 N x m varus and valgus torques with the arm at 90 degrees of flexion.

RESULTS

Range of motion from maximum extension to 50 degrees of flexion produced 3% or less strain in both bands of the reconstructed ligament. Forearm rotation did not significantly affect strain in the anterior or posterior bands (P = .336 and P = .357). Strain at 90 degrees approached 7% in the posterior band (upper 95% confidence interval). Isometric muscle contractions had no measurable effect on strain. Varus torques decreased and valgus torques increased strain significantly (P < .05).

CONCLUSION

In the immediate postoperative period, full extension is safe, while flexion beyond 50 degrees may place deleterious strain on the reconstruction. Isometric flexion and extension exercises do not increase ligament strain but may be unsafe at 90 degrees of flexion, while valgus exercises (internal rotation at the shoulder) can increase strain in the reconstructed ligament.

CLINICAL RELEVANCE

The results have implications for the development of appropriate rehabilitation protocols after ulnar collateral ligament reconstructive surgery.

Validation of a Feedback-Controlled Elbow Simulator Design: Elbow Muscle Moment Arm Measurement

The Allegheny General Hospital (AGH) elbow simulator was designed to be a closed-loop physiologic simulator actuating movement in cadaveric elbow specimens via servoelectric motors that attach to the tendons of the biceps, brachialis, triceps, and pronator teres muscles. A physiologic elbow simulator should recreate the appropriate moment arms throughout the elbow’s range of motion. To validate this design goal, muscle moment arms were measured in three cadaver elbow specimens using the simulator. Flexion-extension moment arms of four muscles were measured at three different pronation/supination angles: fully pronated, fully supinated, and neutral; pronation-supination moment arms were measured at three different flexion-extension angles: 30 deg, 60 deg, and 90 deg. The tendon-displacement method was used in these measurements, in which the ratio of the change in musculotendon length to the change in joint angle was computed. The numeric results compared well with those previously reported; the biceps and pronator teres flexion-extension moment arms varied with pronation-supination position, and vice versa. This is one of the few reports of both flexion-extension and pronation-supination moment arms in the same specimens, and represents the first use of closed-loop feedback control in the AGH elbow simulator. The simulator is now ready for use in clinical studies such as in analyses of radial head replacement and medial ulnar collateral ligament repair.

The influence of type II coronoid fractures, collateral ligament injuries, and surgical repair on the kinematics and stability of the elbow: an in vitro biomechanical study

PURPOSE

This study determined whether elbow stability could be restored with open reduction and internal fixation (ORIF) of type II coronoid fractures and evaluated the role of collateral ligament repair.

METHODS

Passive varus and valgus and simulated active vertical motion were performed using an in vitro elbow motion simulator. Varus/valgus angle and internal/external rotation were measured with the coronoid intact, with 50% removed, and after ORIF. Testing was performed with the collateral ligaments detached and repaired.

RESULTS

Vertical: stability was normal when both the lateral collateral ligament (LCL) and medial collateral ligament (MCL) were repaired, irrespective of the coronoid state. Kinematics were altered with a repaired LCL, incompetent MCL, and type II coronoid fracture (P < .05). Varus: LCL repair restored coronal stability but did not restore internal rotation (P < .05).

CONCLUSIONS

These findings suggest that repair of type II coronoid fractures and injured collateral ligaments should be performed where possible. Over-tensioning the LCL, in the setting of MCL and coronoid deficiency, may contribute to instability.

Radial head fractures--an update

Radial head fractures are the most common fractures occurring around the elbow. Although radial head fractures can occur in isolation, associated fractures and ligament injuries are common. Assembling the clinical presentation, physical examination, and imaging into an effective treatment plan can be challenging. The characteristics of the radial head fracture influence the technique used to optimize the outcome. Fragment number, displacement, impaction, and bone quality are considered when deciding between early motion, fragment excision, and radial head excision, repair, or replacement. Isolated, minimally displaced fractures without evidence of mechanical block can be treated nonsurgically with early active range of motion (ROM). Partial, displaced radial head fractures without evidence of mechanical block can be treated either nonsurgically or with open reduction internal fixation (ORIF), as current evidence does not prove superiority of either strategy. For displaced fractures with greater than 3 fragments, radial head replacement is recommended. Radial head arthroplasty may be preferred over tenuous fracture fixation in the setting of associated ligament injuries when maintenance of joint stability could be compromised by ineffective fracture fixation.

Terrible triad injury of the elbow: current concepts

Fracture-dislocations of the elbow remain among the most difficult injuries to manage. Historically, the combination of an elbow dislocation, a radial head fracture, and a coronoid process fracture has had a consistently poor outcome; for this reason, it is called the terrible triad. An elbow dislocation associated with a displaced fracture of the radial head and coronoid process almost always renders the elbow unstable, making surgical fixation necessary. The primary goal of surgical fixation is to stabilize the elbow to permit early motion. Recent literature has improved our understanding of elbow anatomy and biomechanics along with the pathoanatomy of this injury, thereby allowing the development of a systematic approach for treatment and rehabilitation. Advances in knowledge combined with improved implants and surgical techniques have contributed to better outcomes.

Effect of the posterior bundle of the medial collateral ligament on elbow stability

PURPOSE

The role of the posterior bundle of the medial collateral ligament in stability of the elbow remains poorly defined. The purpose of this study was to determine the effect of sectioning the posterior bundle of the medial collateral ligament on the stability of the elbow.

METHODS

Varus and valgus gravity-loaded passive motion and simulated active vertical motion were performed on 11 cadaveric arms using an in vitro elbow motion simulator. Varus/valgus angle and internal/external rotation of the ulna with respect to the humerus were recorded using an electromagnetic tracking system in varus, valgus, and vertical orientations. Testing was performed on the intact elbow and after sectioning of the posterior bundle of the medial collateral ligament.

RESULTS

With active flexion in the vertical position, the varus/valgus kinematics were unchanged after sectioning of the posterior bundle of the medial collateral ligament. However, in pronation, there was an increase in internal rotation after sectioning of the posterior bundle of the medial collateral ligament compared with that of the intact elbow. This rotational difference was not detected with the forearm in supination. During supinated passive flexion in the varus position, sectioning of the posterior bundle of the medial collateral ligament resulted in increased varus angulation at all flexion angles. In pronation, varus angulation and internal rotation both increased. In supination, sectioning of the posterior bundle of the medial collateral ligament had no effect on maximum varus-valgus laxity or maximum internal rotation. However, in pronation, the maximum varus-valgus laxity increased by 3.5 degrees (30%) and maximum internal rotation increased by 1.0 degrees (29%).

CONCLUSIONS

These results indicate that isolated sectioning of the posterior bundle of the medial collateral ligament causes a small increase in varus angulation and internal rotation during both passive varus and active vertical flexion. This study suggests that isolated sectioning of the posterior bundle of the medial collateral ligament may not be completely benign and may contribute to varus and rotation instability of the elbow. In patients with insufficiency of the posterior bundle of the medial collateral ligament, appropriate rehabilitation protocols (avoiding forearm pronation and shoulder abduction) should be followed when other injuries permit.

Coronal plane partial articular fractures of the distal humerus: current concepts in management

Partial articular fractures of the distal humerus commonly involve the capitellum and may extend medially to involve the trochlea. As the complex nature of capitellar fractures has become better appreciated, treatment options have evolved from closed reduction and immobilization and fragment excision to a preference for open reduction and internal fixation. The latter is now recommended to achieve stable anatomic reduction, restore articular congruity, and initiate early motion. More complex fracture patterns require extensile surgical exposures. The fractures are characterized by metaphyseal comminution of the lateral column and have associated ipsilateral radial head fracture. With advanced instrumentation, elbow arthroscopy may be used in the management of these articular fractures. Though limited to level IV evidence, clinical series reporting outcomes following open reduction and internal fixation of fractures of the capitellum, with or without associated injuries, have demonstrated good to excellent functional results in most patients when the injury is limited to the radiocapitellar compartment. Clinically significant osteonecrosis and heterotopic ossification are rare, but mild to moderate posttraumatic osteoarthrosis may be anticipated at midterm follow-up.

The role of the elbow musculature, forearm rotation, and elbow flexion in elbow stability: an in vitro study

The goal of this study was to define the relative passive contributions of the major muscle groups about the elbow to varus-valgus stability and to determine whether these contributions vary with forearm rotation and elbow flexion. Fourteen cadaveric upper extremities were tested with a custom elbow testing device. The biceps, brachialis, and triceps muscles were loaded to simulate passive tension. The origins and insertions of the remaining muscles that cross the elbow were left intact to assess the contributions of their passive tension to elbow stability. For each specimen, varus-valgus laxity was measured at 30 degrees , 50 degrees , and 70 degrees of elbow flexion with the forearm in full supination, pronation, and neutral rotation, yielding 9 total positions of assessment. Six specimens (series 1) were tested for varus-valgus laxity after the following sequence of conditions: (1) unloaded biceps, brachialis, and triceps; (2) loaded biceps, brachialis, and triceps; (3) release of lateral elbow muscle tension; (4) release of medial elbow muscle tension; and (5) transection of the anterior bundle of the ulnar collateral ligament (UCL). Eight specimens (series 2) were assessed under the same conditions, only with the order of the last 2 conditions reversed for further comparison. Release of the lateral muscles alone increased varus-valgus laxity by a mean of 0.6 degrees to 1.4 degrees , but this was statistically significant only at positions of forearm pronation in series 1 (P < .012) and only at 2 of 9 positions in series 2 (30 degrees of flexion in pronation and 50 degrees of flexion in neutral rotation, P < .049). Release of the medial muscles alone caused a further increase in varus-valgus laxity by a mean of 0.5 degrees to 1.2 degrees , but this was only statistically significant at 30 degrees , 50 degrees , and 70 degrees of flexion in supination (P < .014) and 70 degrees of flexion in pronation (P = .044) in series 1 and only at 30 degrees , 50 degrees , and 70 degrees of flexion in supination in series 2 (P < .046). Release of the anterior bundle of the UCL resulted in a statistically significant increase in elbow varus-valgus laxity at all elbow and forearm positions by a mean of 1.8 degrees to 3.2 degrees (P < .001). Unloading the biceps, triceps, and brachialis caused significant increases in varus-valgus laxity at most elbow testing positions, independent of the position of forearm rotation (P < .046). Thus, the medial elbow musculature and lateral elbow musculature affect total elbow varus-valgus stability to roughly equal magnitudes, and the anterior bundle of the UCL affects stability to over twice the magnitude of either muscle group. The medial elbow musculature mostly affects elbow stability with the arm in supination and the lateral musculature in pronation, where the passive tension in the respective muscles is increased. Furthermore, the medial elbow musculature provided stability to the elbow when the forearm was supinated even with a deficient anterior bundle of the UCL, emphasizing its role as a secondary stabilizer.

Lateral collateral ligament repair restores the initial varus stability of the elbow: an in vitro biomechanical study

OBJECTIVE

Lateral collateral ligament (LCL) repair of the elbow is commonly performed in the management of unstable dislocations and fracture dislocations of the elbow. The appropriateness of clinically employed techniques of LCL repair in restoring elbow kinematics and stability has not been reported. The purpose of this in vitro study was to evaluate the effectiveness of LCL transosseous sutures repair and the influence of ligament tensioning on the initial kinematics and stability of the elbow.

METHODS

Six cadaveric upper extremities were mounted in a motion simulator with tracking system, which enabled both passive and simulated active elbow flexion while measuring the motion of the ulna relative to the humerus. Transosseous sutures were placed in the LCL and passed through a humeral bone tunnel entering at the center of curvature of the capitellum near the lateral epicondyle with exit holes in the lateral supracondylar ridge. With the arm slightly flexed, an actuator pulled on the sutures to achieve 20, 40, and 60 N of LCL repair tension, and the sutures were then secured at that tension.

RESULTS

Transosseous repair of the LCL restored the initial kinematics of the elbow at 20 N of tension. Greater magnitudes of initial repair tension in vitro overcorrected the varus instability causing the elbows to track in excessive valgus and internal rotation.

CONCLUSIONS

These in vitro data suggest that LCL repair using transosseous sutures is a useful technique to restore the initial kinematics of the elbow. An LCL repair tension of 20 N or perhaps slightly less should be employed in clinical studies to confirm these laboratory observations.

Current recommendations for the treatment of radial head fractures

Radial head fractures are the most common type of elbow fractures. Although a consensus has emerged that favors the nonsurgical treatment of undisplaced fractures, controversy surrounds the treatment of displaced radial head fractures. Further research is necessary to provide a better scientific rationale for making treatment recommendations. Options for the treatment of displaced fractures include nonoperative management, fragment excision, whole head excision, open reduction and internal fixation, and radial head arthroplasty. The purpose of this article is to review the mechanisms that result in radial head fracture, to describe important physical findings that assist in identifying injuries associated with radial head fractures, and to define the role of the various interventions described for the treatment of radial head fractures.

Anatomy and biomechanics of the elbow

The elbow is a complex, highly constrained joint that provides critical range of motion to the upper extremity needed for performing the normal activities of daily living. The elbow is protected by a fortress of individual static and dynamic constraints that function together to provide stability. Knowing the identity and specific functions of each stabilizing structure facilitates appropriate diagnosis and treatment of the acutely injured elbow.

Optimizing elbow rehabilitation after instability

Elbow instability is a common clinical problem that requires careful assessment and treatment to achieve a successful outcome. Rehabilitation is a key element in achieving a stable mobile elbow. Careful communication between the treating therapist and surgeon is essential so that an optimal rehabilitation program can be developed and implemented. By understanding the patterns of injury and the biomechanics of the elbow, a good outcome can be achieved in most patients who have elbow instability.

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.

The effect of medial collateral ligament repair tension on elbow joint kinematics and stability

PURPOSE

Medial collateral ligament (MCL) repair is commonly performed for the management of acute or subacute instability after elbow dislocations and fracture-dislocations. The effectiveness of transosseous repair of the MCL, as is typically performed clinically, in restoring the normal kinematics and stability of the elbow is of interest as is the effect of MCL tensioning on the initial stability of the elbow. The purpose of this study was to determine whether suture repair of the MCL is able to restore the normal kinematics and stability of the elbow and to determine the optimal initial MCL repair tension.

METHODS

Six cadaveric upper extremities were mounted in an upper limb joint simulator. Simulated active and passive elbow flexion was generated while the kinematics were measured with the arm in the dependent and the valgus gravity-loaded orientations. After testing the intact elbow, the MCL was released at its humeral attachment and repaired using a transosseous suture technique at three different repair tensions: 20, 40, and 60 N.

RESULTS

Medial collateral ligament repair using a transosseous suture technique restored the kinematics and stability of the MCL-deficient elbow. Motion pathways were affected by the magnitude of initial MCL tension. For all arm orientations and forearm positions, the 20-N and 40-N repairs were not statistically different from each other or from the intact MCL. The 60-N repairs, however, were often statistically different than the other groups, suggesting an overtightening that tended to pull the ulna into a varus position-especially in the midrange of flexion.

CONCLUSIONS

These data suggest that MCL repair using transosseous sutures provide adequate joint stability to permit early motion. There is a broad range of acceptable tensions for MCL repair, which is a favorable, clinically relevant finding. Clinical studies are needed to validate these in vitro results.

Initial repair strengths of two methods for acute medial collateral ligament injuries of the elbow

The purposes of this study were to compare the initial repair strength of the medial collateral ligament (MCL) of the elbow using trans-osseous sutures and suture anchor methods and to determine the effect of repair pretensioning. Twelve, fresh-frozen upper extremities (66 +/- 5 years) were mounted in a valgus-loading system. MCL repairs were performed using trans-osseous suture and suture anchor methods with 20 N or 40 N pretensioning. A cyclic (0.5 Hz), valgus 40 N load was applied 12 cm distal to the elbow axis of flexion. The load was increased by 10 N every 200 cycles until a length increase of 5 mm or catastrophic failure of the repair occurred. Repairs pretensioned with 40 N endured a significantly higher number of cycles and failed at higher loads than those pretensioned with 20 N (p < 0.05). No difference was found in the cycles or load to failure between trans-osseous sutures and suture anchors (p > 0.05). A higher magnitude of pretensioning of MCL repairs was found to increase initial repair strength suggesting that pretensioning should be performed clinically. Despite the comparable failure loads of the trans-osseous suture and suture anchor methods, the failure mechanism differed between the two techniques. The suture anchors usually failed catastrophically when the sutures broke as they passed through the anchor eyelet, while the trans-osseous sutures gradually elongated to the defined failure length by stretching and sliding through the ligament. The use of different suture anchors, suture sizes, or suture materials would likely influence the findings of this study and should be considered when applying these findings clinically.