The effect of arthroscopic sectioning of the lateral ligament complex of the elbow on posterolateral rotatory stability

This study evaluates the relative roles of the radial collateral ligament, the lateral ulnar collateral ligament, and the overlying musculature in posterolateral rotatory instability of the elbow. Fourteen cadaveric upper limbs underwent sequential arthroscopic sectioning of the lateral collateral ligament complex. After sectioning, arthroscopic and fluoroscopic evaluation of a lateral pivot shift test was done. Minimal instability was noted after the first section, but no difference between radial collateral or lateral ulnar collateral ligament sectioning was found. A greater degree of instability was seen between the first and second cut ( P = .0001), but no significant difference was seen between sectioning the 2 groups ( P = .61). Complete instability occurred only after sectioning the overlying musculature. On the basis of this study, injury to both the radial collateral and lateral ulnar collateral ligaments is necessary to cause significant posterolateral rotatory instability of the elbow. Furthermore, the overlying musculature plays an important role in overall stability.     

Elbow instability

An understanding of elbow instability is predicated on knowledge of the anatomy of the lateral collateral ligament complex and of the mechanism and kinematics of elbow subluxation and dislocation. The lateral collateral ligament complex is the key structure involved in recurrent elbow instability and it is virtually always disrupted in elbow dislocations that result from a fall. The ulnar part of the lateral collateral ligament complex (also known as lateral ulnar collateral ligament) is the critical portion of the ligament complex securing the ulna to the humerus and preventing posterolateral rotatory instability. The kinematics of elbow subluxation and dislocation are a three dimensional coupled motion referred to as posterolateral rotatory instability in which the forearm rotates off the humerus in valgus/external rotation during flexion from the extended position. Elbow instability is diagnosed on clinical examination by the lateral pivot-shift test, the posterolateral rotatory apprehension and drawer tests and on radiographic examination by performing stress x-rays. While the lateral pivot-shift test is difficult to perform, the posterolateral rotatory drawer test is much less difficult. The most sensitive test, however, is the posterolateral rotatory apprehension test. A positive apprehension test in a patient presenting with a history of recurrent painful clicking, snapping, clucking, or locking of the elbow should lead one directly to the suspected diagnosis of posterolateral rotatory instability. Treatment is surgical, by repair or reconstruction of the lateral collateral ligament complex, specifically the ulnar part. Deficiencies of the coronoid and/or radial head must be addressed.     

The effect of radial head fracture size on elbow kinematics and stability.

This study determined the effect of radial head fracture size and ligament injury on elbow kinematics. Eight cadaveric upper extremities were studied in an in vitro elbow simulator. Testing was performed with ligaments intact, with the medial collateral (MCL) or lateral collateral (LCL) ligament detached, and with both the MCL and LCL detached. Thirty degree wedges were sequentially removed from the anterolateral radial head up to 120 degrees . Valgus angulation and external rotation of the ulna relative to the humerus were determined for passive motion, active motion, and pivot shift testing with the arm in a vertical (dependent) orientation. Maximum varus-valgus laxity was calculated from measurements of varus and valgus angulation with the arm in horizontal gravity-loaded positions. No effect of increasing radial head fracture size was observed on valgus angulation during passive and active motion in the dependent position. In supination, external rotation increased with increasing fracture size during passive motion with LCL deficiency and both MCL and LCL deficiency. With intact ligaments, maximum varus-valgus laxity increased with increasing radial head fracture size. With ligament disruption, elbows were grossly unstable, and no effect of increasing radial head fracture size occurred. During pivot shift testing, performed with the ligaments intact, subtle instability was noted after resection of one-third of the radial head. In this in vitro biomechanical study, small subtle effects of radial head fracture size on elbow kinematics and stability were seen in both the ligament intact and ligament deficient elbows. These data suggest that fixation of displaced radial head fractures less than or equal to one-third of the articular diameter may have some biomechanical advantages; however, clinical correlation is required.     

Posterolateral rotatory instability of the elbow

Posterolateral rotatory instability of the elbow is a three-dimensional displacement pattern of abnormal external rotatory subluxation of the ulna coupled with valgus displacement on the humeral trochlea. This pattern causes the forearm bones to displace into external rotation and valgus during flexion of the elbow. Injury to the lateral ulnar collateral ligament allows abnormal supination of the ulna on the humerus. The radial head, being locked in the sigmoid (radial) notch of the proximal ulna by the annular ligament, subluxates posterior to the capitellum. The abnormality is usually posttraumatic and presents with locking, snapping, clicking, catching, and recurrent dislocation of the elbow. The clinical diagnosis is suspected from history and confirmed by the physical examination, which includes the posterolateral rotatory instability test. This test often is best performed under fluoroscopy or general anesthesia. Usually the instability is managed with either a repair of the ligament or an isometric reconstruction using a tendon graft.     

Posterolateral rotatory instability of the elbow

Recurrent posterolateral rotatory instability of the elbow is an apparently undescribed clinical condition that is difficult to diagnose. We treated five patients, ranging in age from five to forty years, who had such a lesion and in whom the instability could be demonstrated only by what we call the posterolateral rotatory-instability test. This test involves supination of the forearm and application of a valgus moment and an axial compression force to the elbow while it is flexed from full extension. The elbow is reduced in full extension and must be subluxated as it is flexed in order to obtain a positive test result (a sudden reduction of the subluxation). Flexion of more than about 40 degrees produces a sudden palpable and visible reduction of the radiohumeral joint. The elbow does not subluxate without provocation. The cause for this condition, we think, is laxity of the ulnar part of the lateral collateral ligament, which allows a transient rotatory subluxation of the ulnohumeral joint and a secondary dislocation of the radiohumeral joint. The annular ligament remains intact, so the radio-ulnar joint does not dislocate. Operative repair of the lax ulnar part of the lateral collateral ligament eliminated the posterolateral rotatory instability, as revealed intraoperatively in our five patients.     

Detrimental effects of overstuffing or understuffing with a radial head replacement in the medial collateral-ligament deficient elbow

BACKGROUND: Comminuted radial head fractures associated with an injury of the medial collateral ligament can be treated with a radial head implant. We hypothesized that lengthening and shortening of the radial neck would alter the kinematics and the pressure through the radiocapitellar joint in the medial collateral ligament-deficient elbow. METHODS: The effects of lengthening (2.5 and 5 mm) and shortening (2.5 and 5 mm) of the radial neck were assessed in six human cadaveric upper extremities in which the medial collateral ligament had been surgically released. The three-dimensional spatial orientation of the ulna was recorded during simulated active motion from extension to flexion. Total varus-valgus laxity and ulnar rotation were measured. Radiocapitellar joint pressure was assessed with use of pressure-sensitive film. RESULTS: Radial neck lengthening or shortening of >/=2.5 mm significantly changed the kinematics in the medial collateral ligament-deficient elbow. Lengthening caused a significant decrease (p < 0.05) in varus-valgus laxity and ulnar rotation (p < 0.05), with the ulna tracking in varus and external rotation. Shortening caused a significant increase in varus-valgus laxity (p < 0.05) and ulnar rotation (p < 0.05), with the ulna tracking in valgus and internal rotation. The pressure on the radiocapitellar joint was significantly increased after 2.5 mm of lengthening. CONCLUSIONS: This study suggests that accurate restoration of radial length is important and that axial understuffing or overstuffing of the radiohumeral joint by >/=2.5 mm alters both elbow kinematics and radiocapitellar pressure. CLINICAL RELEVANCE: This in vitro cadaver study indicates that a radial head replacement should be performed with the same level of concern for accuracy and reproducibility of component position and orientation as is appropriate with any other prosthesis.     

Single-strand reconstruction of the lateral ulnar collateral ligament restores varus and posterolateral rotatory stability of the elbow

Because of a lack of biomechanical studies of lateral elbow ligament reconstruction in the literature, the initial stability afforded by 3 different techniques of lateral ulnar collateral ligament reconstruction was evaluated in 8 cadaveric elbows. The arm was mounted in a testing apparatus, and passive flexion was performed with the arm in varus and valgus orientations. A pivot shift test was performed with the arm in the vertical orientation. An electromagnetic tracking device was used to quantify motion pathways. After intact testing, each specimen underwent sectioning of the radial collateral and lateral ulnar collateral ligaments from the lateral epicondyle. Reconstruction of the lateral ulnar collateral ligament was performed in a randomized sequence, consisting of proximal single-strand, distal single-strand, and double-strand tendon grafts. Division of the radial collateral and lateral ulnar collateral ligaments from the lateral epicondyle caused a significant decrease in rotational stability when the pivot shift test was being performed (P <.0001). Varus-valgus stability also decreased after transection of the radial collateral and lateral ulnar collateral ligaments (P <.0001). Reconstruction of the lateral ulnar collateral ligament restored elbow stability to that of the intact state. There was no significant difference in stability between the single- and double-strand repair techniques (P >.05). This study demonstrates that both single- and double-strand reconstructions restore varus and posterolateral elbow stability and may be considered appropriate reconstructive procedures in patients with symptomatic insufficiency of the lateral ligaments of the elbow.     

Effects of elbow flexion and forearm rotation on valgus laxity of the elbow

BACKGROUND: Clinical evaluation of valgus elbow laxity is difficult. The optimum position of elbow flexion and forearm rotation with which to identify valgus laxity in a patient with an injury of the ulnar collateral ligament of the elbow has not been determined. The purpose of the present study was to determine the effect of forearm rotation and elbow flexion on valgus elbow laxity. METHODS: Twelve intact cadaveric upper extremities were studied with a custom elbow-testing device. Laxity was measured with the forearm in pronation, supination, and neutral rotation at 30 degrees, 50 degrees, and 70 degrees of elbow flexion with use of 2 Nm of valgus torque. Testing was conducted with the ulnar collateral ligament intact, with the joint vented, after cutting of the anterior half (six specimens) or posterior half (six specimens) of the anterior oblique ligament of the ulnar collateral ligament, and after complete sectioning of the anterior oblique ligament. Laxity was measured in degrees of valgus angulation in different positions of elbow flexion and forearm rotation. RESULTS: There were no significant differences in valgus laxity with respect to elbow flexion within each condition. Overall, for both groups of specimens (i.e., specimens in which the anterior or posterior half of the anterior oblique ligament was cut), neutral forearm rotation resulted in greater valgus laxity than pronation or supination did (p < 0.05). Transection of the anterior half of the anterior oblique ligament did not significantly increase valgus laxity; however, transection of the posterior half resulted in increased valgus laxity in some positions. Full transection of the anterior oblique ligament significantly increased valgus laxity in all positions (p < 0.05). CONCLUSIONS: The results of this in vitro cadaveric study demonstrated that forearm rotation had a significant effect on varus-valgus laxity. Laxity was always greatest in neutral forearm rotation throughout the ranges of elbow flexion and the various surgical conditions. CLINICAL RELEVANCE: The information obtained from the present study suggests that forearm rotation affects varus-valgus elbow laxity. Additional investigation is warranted to determine if forearm rotation should be considered in the evaluation and treatment of ulnar collateral ligament injuries of the elbow joint.     

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

The purpose of this study was to determine the relative contribution of muscle activity and the effect of forearm position on the stability of the medial collateral ligament (MCL)-deficient elbow. Simulated active and passive elbow flexion with the forearm in both supination and pronation was performed using a custom elbow testing apparatus. Testing was first performed on intact specimens, then on MCL-deficient specimens. Elbow instability was quantified using an electromagnetic tracking device by measuring internal-external rotation and varus-valgus laxity of the ulna relative to the humerus. Compared with the intact elbow, transection of the MCL, with the arm in a vertical orientation, caused a significant increase in internal-external rotation during passive elbow flexion with the forearm in pronation, but forearm supination reduced this instability. Overall, following MCL transection the elbow was more stable with the forearm in supination than pronation during passive flexion. In the pronated forearm position simulated active flexion also reduced the instability detected during passive flexion, with the arm in a varus and valgus gravity-loaded orientation. The maximum varus-valgus laxity was significantly increased with MCL transection regardless of forearm position during passive flexion. We concluded that active mobilization of the elbow with the arm in vertical orientation during rehabilitation is safe in the setting of an MCL-deficient elbow with the forearm in a fully supinated and pronated position. Splinting and passive mobilization of the MCL-deficient elbow with the forearm in supination should minimize instability and valgus elbow stresses should be avoided throughout the rehabilitation period.     

The Wrightington approach to the radial head: biomechanical comparison with the posterolateral approach

PURPOSE: The Wrightington approach to the radial head involves elevating anconeus from the proximal ulna to expose the supinator crest and then osteotomizing the bony insertion of the lateral ligament complex to the ulna. This avoids incising through the substance of the lateral ligament complex. The purpose of this study was to determine if there is any difference in laxity changes between using the posterolateral versus the Wrightington approach in performing surgery upon the radial head in a cadaveric model. METHODS: Ten cadaveric elbows had a radial head fracture created and the medial collateral ligament divided. They then sequentially had the posterolateral or Wrightington approach to the radial head, fracture fixation, head excision, and replacement. After each step, valgus and varus laxity and ulnar rotation were determined with an electromagnetic tracking system. RESULTS: After each step, there was a greater increase in valgus and varus laxity in the posterolateral group compared with the Wrightington group. After surgical exposure, radial head fracture fixation, and radial head excision, there was a statistically significant difference in the changes in rotation between the posterolateral and Wrightington approaches, with the former resulting in an increase in external and the latter an increase in internal rotation. CONCLUSIONS: These results suggest that the newly described Wrightington approach is biomechanically superior to the posterolateral approach with regard to changes in elbow laxity after surgery to the radial head.     

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

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

Posterolateral rotatory instability of the elbow following radial head resection

BACKGROUND: Resection is a common procedure for the treatment of comminuted fractures of the radial head. While radial head resection is associated with a high success rate when performed for appropriate indications, a number of well-defined biomechanical complications have been reported following this procedure, including proximal migration of the radius, the development of valgus deformity, and recurrent elbow instability in the acute setting. However, posterolateral rotatory instability has not previously been recognized as a complication of radial head resection. While the absence of the radial head makes the diagnosis difficult, we have identified a series of patients with posterolateral rotatory instability following radial head resection. We believe that this instability is secondary to unrecognized lateral ulnar collateral ligament deficiency. METHODS: Between November 1995 and September 2000, forty-two patients were evaluated because of elbow or forearm complaints following radial head resection. Seven patients (17%) were diagnosed with posterolateral rotatory instability on the basis of characteristic clinical and radiographic findings. RESULTS: The study group included five men and two women with a mean age of forty-two years. All seven patients had had radial head excision for the treatment of a comminuted radial head fracture at a mean of forty-four months (range, four months to sixteen years) prior to referral. All seven patients had lateral elbow pain, a sense of instability and/or weakness, and a positive lateral pivot-shift test. Posterolateral rotatory instability secondary to lateral ulnar collateral ligament insufficiency was confirmed intraoperatively in the four patients who were managed surgically. CONCLUSIONS: Clinicians should be aware that posterolateral rotatory instability may be a cause of unexplained elbow pain and instability following radial head resection. This diagnosis has implications for the prevention and treatment of this condition.     

LUCL-Bandplastik mit Trizepssehnentransplantat zur Therapie der posterolateralen Rotationsinstabilität am Ellenbogen

Objective

Re-establishment of radial stability within the elbow joint in cases of arthroscopically or clinically confirmed posterolateral rotatory instability.

Indications

Posttraumatic or chronic degenerative posterolateral rotatory instability at least grade I–II according to O’Driscoll.

Contraindications

Elbow stiffness or elbow arthritis and lateral epicondylitis, if a posterolateral rotatory instability has been excluded as the reason for the symptoms.

Surgical technique

Reconstruction or augmentation of the insufficient lateral ulnar collateral ligament (LUCL) with an autologous triceps tendon graft. A stripe of the triceps tendon is fixed at the epicondylus humeri radialis and at the base of the annular ligament at the proximal radial ulna with tenodesis screws or buttons, then the extensor origins, which were detached before are fixated as well.

Postoperative management

Postoperative treatment with an elbow orthesis for 6 weeks, in the first 4 weeks limitation of complete extension and flexion, full weight bearing after 3 months.

Results

Retrospective analysis of 47 LUCL reconstructions from 2008–2010 with good results concerning pain reduction and acceptance, improvement of the Mayo Elbow Performance Score from 49 to 82, low complication rate with one elbow stiffness, one temporary ulnar nerve lesion, and one recurrent instability.     

Chronic lateral elbow instability

Posterolateral rotatory instability of the elbow is the most common pattern of chronic lateral elbow instability. The primary lesion in posterolateral rotatory instability is injury or attenuation of the lateral ulnar collateral ligament. Posterolateral rotatory instability is diagnosed on the basis of careful history taking and specific physical examination techniques. Reconstruction of the lateral ulnar collateral ligament with repair of the surrounding soft tissue structures is recommended in patients who have symptoms of recurrent lateral instability. Open and arthroscopic reconstruction techniques have resulted in improvement of elbow function and satisfactory results in most patients, although mild limitation in terminal extension of the elbow is a common finding.     

Muscle forces and pronation stabilize the lateral ligament deficient elbow.

The influence of muscle activity and forearm position on the stability of the lateral collateral ligament deficient elbow was investigated in vitro, using a custom testing apparatus to simulate active and passive elbow flexion. Rotation of the ulna relative to the humerus was measured before and after sectioning of the joint capsule, and the radial and lateral ulnar collateral ligaments from the lateral epicondyle. Gross instability was present after lateral collateral ligament transection during passive elbow flexion with the arm in the varus orientation. In the vertical orientation during passive elbow flexion, stability of the lateral collateral ligament deficient elbow was similar to the intact elbow with the forearm held in pronation, but not similar to the intact elbow when maintained in supination. This instability with the forearm supinated was reduced significantly when simulated active flexion was done. The stabilizing effect of muscle activity suggests physical therapy of the lateral collateral ligament deficient elbow should focus on active rather than passive mobilization, while avoiding shoulder abduction to minimize varus elbow stress. Passive mobilization should be done with the forearm maintained in pronation.     

Elbow joint instability: A kinematic model

The effect of simultaneous ulnar and radial collateral ligament division on the kinematics of the elbow joint is studied in a cadaveric model. Severance of the anterior part of the ulnar collateral ligament and the annular ligament led to significant elbow joint instability in valgus and varus stress and in forced external and internal rotation. The mean maximum laxity in valgus stress and forced external rotation were 5.7° and 13.2°. The forearms of the elbow joint specimens were transfixed in maximum pronation. During valgus and varus stress the corresponding spontaneous ulnar rotation of the specimens was recorded. The reproducibility of the instability pattern suggests that this model is suitable for evaluating stabilizing procedures aimed at correction of elbow joint instability before these procedures are introduced into patient care.     

Reconstructive treatment of posterolateral rotatory instability of the knee: a biomechanical study

Twelve cadaveric knees were tested to determine effective reconstructive treatment for severe chronic posterolateral rotatory knee instability accompanied by excessive varus and posterior laxity. Posterolateral, varus, and posterior laxity were measured, first with the ligaments intact, then after complete sectioning of the posterior cruciate ligament (PCL) and posterolateral structures, and finally after reconstruction of these structures in different orders. The increases in those laxities were produced following the sectioning of all of the structures and disappeared throughout the flexion range after combined reconstruction of the PCL, lateral collateral ligament (LCL), and popliteus tendon. However, some residual increase in the laxity was always observed if any of the three structures were excluded from reconstruction. Therefore, combined reconstruction of the PCL, LCL, and popliteus tendon is essential and adequate for treating severe chronic posterolateral rotatory instability.     

Ligamentous reconstruction for posterolateral rotatory instability of the elbow.

Eleven consecutively seen patients who had posterolateral rotatory instability of the elbow joint were managed operatively. The radial collateral-ligament complex was advanced and imbricated in three of them. In seven patients, the ulnar band of the radial collateral ligament (the lateral ulnar collateral ligament) was reconstructed with the palmaris longus tendon and in two of the seven, the reconstruction was augmented with a prosthetic ligament. The ligament was reconstructed with the lateral one-third of the triceps fascia in the remaining patient. Stability was obtained in ten patients, and seven patients had an excellent functional result. There was one failure in one of the patients in whom the ulnar band of the radial collateral ligament had been reconstructed with the palmaris longus tendon and augmented with a prosthetic ligament.     

Surgical reconstruction for posterolateral rotatory instability of the elbow

We reviewed the results of 10 patients (10 elbows) who underwent surgical reconstruction for clinically symptomatic posterolateral rotatory instability of the elbow. The symptoms resulted from previous dislocation or a hyperextension or varus stress injury of the elbow. Two elbows had underlying preexisting varus deformity. Surgical reconstruction was performed with a tendon graft in 6 elbows and reattachment of the lateral ulnar collateral ligament to the humerus in 4. Postoperatively, no patient had residual instability or a positive pivot shift test in the elbow. Results were graded as excellent or good in 8 and fair in 2. All patients with excellent results had surgical reconstruction with a tendon graft. Subjective assessment revealed that all 10 patients were satisfied with the outcome of the surgery. Accurate recognition of posterolateral rotatory instability of the elbow is important for appropriate management. Surgical ligament reconstruction or repair is the most favorable treatment option for restoration of normal elbow function. The choice of reconstruction with a tendon graft appeared to produce better results than the reattachment of the injured ligament by itself in achieving an excellent outcome.     

The in vivo isometric point of the lateral ligament of the elbow

BACKGROUND: Many reports have discussed reconstruction of the lateral ulnar collateral ligament for the treatment of posterolateral rotatory instability of the elbow, but information regarding the isometric point of the lateral ligament of the elbow is limited. The purposes of the present study were to investigate the in vivo and three-dimensional length changes of the lateral ulnar collateral ligament and the radial collateral ligament during elbow flexion in order to clarify the role of these ligaments as well as to identify the isometric point for the reconstructed lateral ulnar collateral ligament on the humerus where the grafted tendon should be anchored. METHODS: We studied in vivo and three-dimensional kinematics of the normal elbow joint with use of a markerless bone-registration technique. Magnetic resonance images of the right elbows of seven healthy volunteers were acquired in six positions between 0 degrees and 135 degrees of flexion. We created three-dimensional models of the elbow bones, the lateral ulnar collateral ligament, and the radial collateral ligament. The ligament models were based on the shortest calculated paths between each origin and insertion in three-dimensional space with the bone as obstacles. We calculated two types of three-dimensional distances for the ligament paths with each flexion position: (1) between the center of the capitellum and the distal insertions of the ligaments (to investigate the physiological change in ligament length) and (2) between eight different humeral origins and the one typical insertion of the lateral ulnar collateral ligament (to identify the isometric point of the reconstructed lateral ulnar collateral ligament). RESULTS: The three-dimensional distance for the lateral ulnar collateral ligament was found to increase during elbow flexion, whereas that for the radial collateral ligament changed little. The path of the lateral ulnar collateral ligament gradually developed a detour because of the osseous protrusion of the lateral condyle with flexion. The most isometric point for the reconstructed lateral ulnar collateral ligament was calculated to be at a point 2 mm proximal to the center of the capitellum. CONCLUSIONS: The radial collateral ligament is essentially isometric, but the lateral ulnar collateral ligament is not. The lateral ulnar collateral ligament is loose in elbow extension and becomes tight with elbow flexion.