This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF) Free
Right arrow Letters to the Editor: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when Letters to the Editor are posted
Right arrow Alert me if a correction is posted
Services
Right arrow E-mail this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My File Cabinet
Right arrow Download to citation manager
Right arrow Rights and Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by COHEN, M. S.
Right arrow Articles by HASTINGS II, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by COHEN, M. S.
Right arrow Articles by HASTINGS II, H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us   Add to Facebook   Add to Technorati   Add to Twitter  
What's this?
The Journal of Bone and Joint Surgery 79:225-33 (1997)
© 1997 The Journal of Bone and Joint Surgery, Inc.

Rotatory Instability of the Elbow. The Anatomy and Role of the Lateral Stabilizers*

MARK S. COHEN, M.D.{dagger}, CHICAGO, ILLINOIS and HILL HASTINGS II, M.D.{ddagger}, INDIANAPOLIS, INDIANA

Investigation performed at The Indiana Hand Center, Indianapolis


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Posterolateral rotatory instability of the elbow has been attributed to disruption of the ulnar part of the lateral collateral ligament. Forty fresh cadavera were studied to define the ligamentous anatomy of the lateral aspect of the elbow specifically as it relates to rotatory instability. The dissections revealed a broad conjoined insertion of the lateral collateral and annular ligaments onto the proximal aspect of the ulna. This insertion was bilobed (type I) in twenty-two specimens and broad (type II) in eighteen specimens. Serial sectioning studies revealed primary and secondary stabilizers of the lateral aspect of the elbow. In addition to the lateral collateral ligament and the annular ligament, the extensor muscle origins provide stability through fascial bands and intermuscular septa. CLINICAL RELEVANCE: The findings of this study suggest that post-traumatic posterolateral rotatory instability of the elbow is the result of attenuation or disruption of both the ligamentous and the muscular origins from the lateral epicondyle of the humerus. Injury to these structures should be avoided during operative exposures for procedures such as débridement of the elbow for recalcitrant lateral epicondylitis, resection of the radial head, or capsular release for a stiff elbow. If immobilization is necessary postoperatively, the forearm should be held in pronation.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
While the functional anatomy of the ligamentous support on the medial aspect of the elbow has been well defined17,46,48, the soft-tissue constraints on the lateral aspect of the elbow have not. There is considerable disagreement as to the importance of the lateral soft-tissue structures in the development of post-traumatic instability of the elbow35,38,46,47. The ulnar part of the lateral collateral ligament has been believed by some to be the essential component of lateral stability of the elbow30,31,36, although the descriptions of this structure as well as that of other soft-tissue constraints on the lateral side of the elbow have varied considerably in the literature6,7,11,13,15,24,25,33,39,41,45,46,49.

We performed this anatomical study in order to define the musculotendinous as well as the ligamentous structures on the lateral aspect of the elbow, with specific emphasis on the role of these structures in the development of posterolateral instability of the elbow.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Forty upper extremities from fresh cadavera of adults who had no history of abnormality about the elbow were studied. The skin on the lateral aspect of the elbow was incised and reflected to reveal the fascia of the lateral muscles of the elbow. The anconeus was released from its ulnar insertion and bluntly reflected superiorly to reveal the underlying supinator and lateral ligamentous complex of the elbow.

The specimens were secured and mounted on a specially designed frame to measure posterolateral rotatory instability of the elbow (Fig. 1). The humeral shaft was fixed with two large threaded Steinmann pins placed bicortically through posterior stab incisions. A third Steinmann pin was placed into the distal aspect of the radius five centimeters proximal to the radial styloid process. The specimens were then mounted onto the testing apparatus with the forearm in full supination and the elbow flexed 40 degrees. This is the position of maximum rotatory displacement of the elbow clinically31,36.



View larger version (36K):
[in this window]
[in a new window]
  		Fig. 1 Diagram of the experimental setup. The cadaveric specimen is mounted on a frame designed for the evaluation of posterolateral instability of the elbow. Two large Steinmann pins secure the humeral shaft to the frame. The elbow is positioned in 40 degrees, and the forearm is in full supination.

 
The angle of flexion of the ulnohumeral articulation was determined under fluoroscopic control and was recorded. A true lateral image of the elbow was produced by placing the beam of the fluoroscopic unit parallel to the distal articular surface of the humerus4. A Kirschner wire was placed in the center of the trochlea and capitellum. This represents the true axis of the elbow, and its position was confirmed by the connection of a line collinear with the anterior cortex of the distal aspect of the humerus and the center of the radial head1,27. A second Kirschner wire was placed parallel to this in the ulna where the anterior humeral line crossed the proximal ulnar cortex.

The specimens were preloaded with a one-pound (0.45-kilogram) weight attached to the distal Steinmann pin five centimeters from its insertion into the radius (Fig. 1), to provide a standard rotatory moment to the elbow. Four cutting sequences were designed to determine the primary and secondary stabilizers of the lateral aspect of the elbow. The specimens were randomly assigned to one of the four sequences so that there were ten specimens in each group. Individual structures were defined and sharply sectioned. Rotatory displacement of the elbow was determined by measurement of the change in the distance between the tips of the Kirschner wires as the ulna and forearm unit rotated away from the humerus. Displacement for each specimen was expressed as a percentage of the final maximum rotatory displacement with all restraints sectioned. Paired t tests were used to determine if individual cuts significantly increased rotatory instability within each group. Because of the multiple comparisons performed, a Bonferroni adjustment was used (0.05 divided by 14.0) and the differences were significant at p <= 0.003.

Pilot studies were performed on ten specimens to define the anatomy and to aid in the design of the sectioning studies. These studies revealed a broad common insertion of the annular ligament and lateral collateral ligament onto the ulna slightly posterior and continuing distal to the radial notch. This observation is similar to those reported by Martin25 and Johansson19 as well as to numerous anatomical illustrations of the lateral ligaments of the elbow10,12,13,33,49,51. This conjoined ligament became taut with the forearm in supination. The margins of the ligament could be defined by gentle teasing of the thin overlying fibers of the supinator off the proximal aspect of the ulna to reveal its firm distal margin. Proximally, the translucent joint capsule could be reflected to reveal the proximal margin of this stout conjoined insertion. This thin lateral joint capsule was found to have no stabilizing effect on the elbow. The anatomy of the conjoined insertion of the annular and lateral collateral ligaments onto the ulna was recorded, photographed, and measured with Vernier calipers (Cole-Parmer, Chicago, Illinois).

Other potential contributors to stability of the lateral aspect of the elbow, as determined from the pilot studies, were (1) the supinator muscle, which arises from the lateral epicondyle of the humerus and the proximal aspect of the ulna and inserts onto the radial shaft, reinforcing the underlying collateral ligament complex from its humeral origin to its ulnar insertion; (2) a stout fascial band of the extensor carpi ulnaris, which originates at the inferior aspect of the lateral humeral epicondyle and inserts onto the ulna several centimeters distal to the combined insertion of the annular ligament and the lateral collateral complex; and (3) the extensor muscle mass with a particularly strong intermuscular septum between the extensor digitorum communis and the extensor digiti quinti.

Serial Sectioning Sequences
Four sequences were designed to evaluate the contribution of the structures of the lateral aspect of the elbow to stability. All ligamentous, muscular, and septal structures from the humerus to the forearm were ultimately sectioned in each group, allowing comparison of the relative contribution of each structure to the over-all stability of the elbow. Group I was designed to determine if the extensor carpi ulnaris fascial band or the annular ligament, or both, was the only structure responsible for support of the lateral aspect of the elbow. Group II was designed to evaluate the inferior half of the origin of the lateral collateral ligament relative to the entire ligament. This was elevated specifically to test the importance of the ulnar part of the lateral collateral ligament, which has been described as originating inferior to the lateral epicondyle26,30. Groups III and IV were designed to evaluate the relative contribution of the extensor muscles and their septa. In Group III, the ligament complex and extensors were sectioned distally, and in Group IV they were sectioned proximally.

In Group I, the extensor carpi ulnaris fascial band at its ulnar osseous insertion was sectioned first (Fig. 2). Next, the annular ligament with overlying extensor tendons was incised, under fluoroscopic guidance, longitudinally at the center of the radial head. This incision began several millimeters proximal to the radial head and continued distally in line with the radius to the radial neck. The annular ligament was gently dissected off the periosteum of the head and neck of the radius. The entire radiocapitellar articulation, which consisted of the lateral collateral ligament and the extensor muscle tendinous origins, was then sectioned to the top of the capitellum at its connection with the anterior aspect of the humeral shaft.



View larger version (87K):
[in this window]
[in a new window]
  		Figs. 2 through 5: Illustrations of the serial sectioning sequences for the four groups. In all sequences, the deep ligament and supinator layer is on the left and the overlying extensor muscles, fascia, and their septa are on the right. SUP. = supinator, ECRB = extensor carpi radialis brevis, EDC = extensor digitorum communis, EDQ = extensor digiti quinti, and ECU = extensor carpi ulnaris. Fig. 2: Group I. First, the extensor carpi ulnaris fascial band was divided at its ulnar insertion, then the annular ligament was sectioned at the center of the radial head, and then all ligaments and musculotendinous origins were released from the lateral epicondyle.

 
In Group II, all structures at and inferior to the axis of rotation at the radiocapitellar joint, including the inferior fibers of the lateral collateral ligament as well as the overlying inferior extensor muscles, were sectioned after division of the extensor carpi ulnaris fascial band off the ulna (Fig. 3). Care was taken to document division of the septum between the extensor digitorum communis and the extensor digiti quinti, which was found consistently to insert into the lateral epicondyle at and just inferior to the axis of rotation of the elbow. Next, all structures superior to the axis of the elbow, including the remaining collateral ligament and superior extensor muscle tendons, were sectioned to the top of the capitellum. To complete the release of all lateral structures, the annular ligament was then incised at the center of the radial head and was dissected free from the underlying periosteum.



View larger version (85K):
[in this window]
[in a new window]
  		Fig. 3 Group II. First, the extensor carpi ulnaris fascial band was incised off the ulna. Next, all structures, including the inferior fibers of the lateral collateral ligament, supinator, and extensor tendon origins (which included the septum between the extensor digitorum communis and the extensor digiti quinti), were released off the humerus at and beneath the center of the axis of rotation of the elbow. The superior humeral ligamentous and musculotendinous origins were then divided to the superior aspect of the capitellum. Finally, the annular ligament was incised to complete the release of all lateral supporting structures.

 
For Group III, the first step was distal sectioning of the ligament complex at its insertion onto the ulna (Fig. 4). The remaining supinator and extensor carpi ulnaris fascial band attachments were then released from the ulna distal to this. The extensor muscles (extensor carpi ulnaris, extensor digitorum communis, extensor digiti quinti, and extensor carpi radialis brevis as well as the septum between the extensor digitorum communis and the extensor digiti quinti) were divided distally over the neck of the radius. To complete the lateral sectioning, the entire radiocapitellar joint was released, including the lateral collateral ligament and the overlying extensor muscle tendinous origins.



View larger version (85K):
[in this window]
[in a new window]
  		Fig. 4 Group III. First, the conjoined lateral collateral and annular ligaments were released off the ulna. Next, the extensor carpi ulnaris fascial band and more distal supinator fibers were sectioned from the ulna. The extensor muscles, including the septum between the extensor digitorum communis and the extensor digiti quinti, were divided over the radial neck. Finally, the humeral origin of the lateral collateral ligament and supinator tendon were sharply divided.

 
For Group IV, the procedure began with release of the lateral collateral ligament off the humerus at its proximal origin (Fig. 5). The lateral collateral ligament was defined and sectioned beneath the extensor tendon origins at the radiocapitellar joint. Care was taken to define bluntly the plane between the deep collateral-and-supinator layer and the superficial extensor-tendon layer, and a Freer elevator was used to mark this plane. (This was easily defined distally at the region of the radiocapitellar joint. More proximally, the extensor origins and the septum of the extensor digitorum communis and the extensor digiti quinti coalesce and become indistinguishable from the lateral collateral ligament toward their attachment at the epicondyle.) Once the deep ligamentous layer had been sectioned, the entire overlying extensor tendon origins were cut at the radiocapitellar joint. Care was taken to document that the lateral collateral ligament had been sectioned entirely up to the top of the capitellum in each specimen. In this way, the relative contributions of the extensor muscles and their septa were evaluated by sectioning distally first (Group III) and proximally second (Group IV). To complete the sectioning of all lateral structures, the annular ligament was divided at the center of the radial head and dissected away from the underlying periosteum.



View larger version (83K):
[in this window]
[in a new window]
  		Fig. 5 Group IV. First, the lateral collateral ligament and supinator tendon were released from the humerus beneath the intact extensor tendon origin. Next, the extensor muscles, including the extensor carpi ulnaris fascial band as well as the septum between the extensor digitorum communis and the extensor digiti quinti, were divided. Finally, the annular ligament was sectioned to complete the release of all lateral supporting structures.

 


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 

Anatomical
The lateral collateral and annular ligaments formed a broad conjoined insertion onto the proximal aspect of the ulna in all forty specimens. The insertion, which was a mean (and standard deviation) of 2.3 ± 0.4 centimeters long, began at the proximal margin of the radial head in thirty specimens, two to three millimeters distal to the proximal margin in seven, and two to three millimeters proximal to the proximal margin in three. The insertion attached just inferior to the radial notch and progressed along a rough ridge in line with the supinator crest of the ulna.

Two types of conjoined lateral collateral and annular ligamentous insertions were observed. In twenty-two specimens, the lateral ligament complex was bilobed (type I), with longitudinal fibers inserting at the radial head and a second oblique bundle inserting distally along the ulna (Fig. 6). The fiber arrangement was most pronounced with the forearm in supination, which caused the ligament complex to become taut. In twelve of the twenty-two specimens, there was a small but definite one-to-three-millimeter gap separating these bundles. In one specimen, the proximal band was subdivided into several strips, as previously described25.



View larger version (97K):
[in this window]
[in a new window]
  		Fig. 6 Illustration of the type-I insertion of the lateral collateral and annular ligaments, which was seen in twenty-two specimens. The conjoined ligament insertion on the ulna is bilobed.

 
In eighteen specimens, the lateral ligaments inserted in a broad single expansion with a smooth transition between the proximal and distal fibers (type II) (Fig. 7). One specimen had a second three-millimeter band inserting four millimeters proximally, at the distal aspect of the olecranon fossa. In one specimen, the lateral collateral ligament had a so-called narrow but stout band of ligamentous tissue42, which inserted onto the ulna at the distal margin of the annular ligament.



View larger version (109K):
[in this window]
[in a new window]
  		Fig. 7 Illustration of the type-II insertion of the lateral collateral and annular ligaments, which was seen in eighteen specimens. A single broad conjoined ligament inserts onto the ulna.

 
The supinator tendon in all specimens crossed this ligament complex obliquely from distal to proximal at its ulnar attachment and became confluent with the underlying annular and lateral collateral ligaments more proximally, at its humeral origin. Its thickness and development were somewhat variable. In some specimens, the supinator tendon was thin and transparent, allowing identification of the underlying conjoined ligament. In others, it was well developed and concealed the underlying ligament complex. In one specimen, the supinator had an additional four-millimeter attachment onto the ulna superficial to the conjoined collateral complex at its distal margin.

A distinct band of extensor carpi ulnaris fascia was noted to course from the inferior aspect of the lateral epicondyle to the ulna in thirty-six specimens. This fascial band, illustrated in several anatomical texts11,23,43, became taut when the forearm was in supination. It could best be observed by reflection of the anconeus superiorly to expose this fascial strip on the undersurface of the extensor carpi ulnaris at its inferior margin. The band averaged 6.1 ± 0.7 centimeters in length and 0.8 ± 0.2 centimeter in width and attached onto the ulna a mean of 4.7 ± 0.8 centimeters distal to the center of the radial head. In four specimens, this fascial thickening was identified but could not be measured accurately as it blended with the remaining fascia on the undersurface of the extensor carpi ulnaris. The anterior margin of this band reflected medially and blended with the underlying supinator and the combination of the annular ligament and the lateral collateral ligament in twenty-six specimens. In all ten specimens in Group IV, it was easy to separate this reflection bluntly from the underlying supinator tendon in the region of the radiocapitellar joint. In four specimens, the fascial band became confluent with the combination of the annular ligament and the lateral collateral ligament complex over the radial head, where it could not be isolated.

A stout four-to-six-millimeter intermuscular septum was noted to separate the extensor digitorum communis and extensor digiti quinti muscle compartments. This septum also tightened when the forearm was in supination. It originated on the lateral epicondyle just anterior to the extensor carpi ulnaris fascial band (Fig. 2). Its anterior border consistently defined the axis of rotation of the elbow. The septum was easily identified over the radiocapitellar joint during the sectioning studies and was separate from the underlying supinator and lateral ligament complex. Proximal to the radiocapitellar joint, this septal band coalesced with the underlying lateral collateral ligament complex and proximal extensor tendons at their humeral origin.

Serial Sectioning Sequences

Group I
Sectioning of the extensor carpi ulnaris fascial band alone resulted in a mean (and standard deviation) of only 5 ± 4 per cent of the total rotatory motion of the elbow (Fig. 8). Incision of the annular ligament at the center of the radial head increased lateral rotation to a mean of 15 ± 8 per cent of the total rotatory motion. This incision disrupted most of the conjoined lateral collateral and annular ligament fibers. However, some proximal elements of the lateral collateral ligament continuing inferior to this incision accounted for the remaining stability of the elbow. Sectioning of all of the fibers originating on the lateral epicondyle allowed the radius and the ulna to rotate maximally away from the trochlea. Each section significantly increased the rotatory motion (p <= 0.001).



View larger version (16K):
[in this window]
[in a new window]
  		Figs. 8 through 11: Graphs of the mean percentage (and standard deviation) of maximum rotatory displacement of the elbow after sectioning of the individual structures in each group. Each cut in each group significantly increased the rotatory displacement of the elbow (p <= 0.001). Fig. 8: Group I. Sectioning of the extensor carpi ulnaris (ECU) fascial band and the annular ligament led to only 15 per cent of total rotatory motion.

 

Group II
Sectioning of the extensor carpi ulnaris fascial band again resulted in a mean of only 5 ± 3 per cent of the total lateral rotatory motion (Fig. 9). Sectioning of the lateral collateral ligament and the extensor tendon mass (including the septum between the extensor digitorum communis and extensor digiti quinti muscles) at and beneath the axis of rotation at the epicondyle increased rotatory motion to a mean of 15 ± 8 per cent. Although a number of stabilizers of the lateral aspect of the elbow were sectioned, the anterior lateral collateral fibers remained intact and supported the ulna and forearm unit through the conjoined insertion on the ulna. Sectioning of the remaining fibers originating on the humerus superiorly to the anterior capitellar margin allowed a mean of 76 ± 12 per cent of total rotation to occur. The intact annular ligament attachments to the humerus were responsible for the remaining stability of the elbow (primarily through the anterior fibrous elbow capsule25,41,44 ), as sectioning of them led to maximum rotatory displacement. Each cut significantly increased rotatory displacement (p <= 0.001).



View larger version (18K):
[in this window]
[in a new window]
  		Fig. 9 Group II. There was minimum rotatory motion after division of the ligaments and tendons originating on the inferior aspect of the lateral epicondyle. ECU = extensor carpi ulnaris.

 

Group III
Sectioning of the conjoined insertion of the lateral collateral and annular ligaments off the proximal aspect of the ulna resulted in a mean of 11 ± 6 per cent of the total rotatory motion of the elbow (Fig. 10). Incision of the remaining supinator and extensor carpi ulnaris band attachments off the ulna led to a mean of 23 ± 5 per cent of total rotatory motion. The extensor muscles and fasciae, because of their course from the dorsal aspect of the forearm in supination to their origin on the lateral epicondyle, independently prevent the forearm unit from rotating away from the humerus in this situation. Sectioning of the remaining extensor muscles (the extensor carpi ulnaris and the extensor digitorum communis as well as the septum between the extensor digitorum communis and the extensor digiti quinti) over the radial neck increased rotatory motion to a mean of 53 ± 10 per cent. The remaining stability of the lateral aspect of the elbow resulted from the annular and lateral collateral ligament complex. Although released from the ulna, this stout ligamentous structure still functioned to limit lateral rotation of the forearm unit because of its tight approximation to the underlying radial head. The annular ligament also sends fibers that attach to the periosteum of the underlying radial head and neck25. In this setting, these fibers are still connected to the humerus through the intact origin of the lateral collateral ligament. Sectioning of this origin at the lateral epicondyle resulted in maximum rotatory displacement of the elbow. Each cut significantly increased the lateral rotatory motion (p <= 0.001).



View larger version (19K):
[in this window]
[in a new window]
  		Fig. 10 Group III. Little instability was noted when the conjoined lateral collateral ligament (LCL) and annular ligament (AL) was released at its ulnar insertion. Stability was provided by the extensor muscles with their septal bands and fasciae. ECU = extensor carpi ulnaris.

 

Group IV
Sectioning of the lateral collateral origin at the lateral epicondyle while the overlying extensor tendon origins were preserved resulted in a mean of 19 ± 8 per cent of the total rotatory motion of the elbow (Fig. 11). Incision of the extensor tendons with their septa and fasciae led to a mean of 76 ± 6 per cent of total rotatory motion. The remaining support for the forearm unit resulted from the anterior connection of the annular ligament with the humerus through the anterior aspect of the capsule, the brachialis, and the overlying extensor carpi radialis longus origin. Sectioning of the annular ligament led to maximum rotatory displacement of the elbow. Each cut significantly increased the motion of the lateral aspect of the elbow (p <= 0.001).



View larger version (18K):
[in this window]
[in a new window]
  		Fig. 11 Group IV. Sectioning of the entire lateral collateral ligament (LCL) from the humerus led to only 19 per cent of total rotatory motion with the overlying extensor origins intact. This sequence documents the importance of the extensor mass as a secondary stabilizer of the lateral aspect of the elbow. ECU = extensor carpi ulnaris.

 


   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Disruption of the stabilizers of the lateral aspect of the elbow leads to rotatory subluxation of the ulna and forearm away from the trochlea with the forearm in supination. In most instances, the injury results from a combination of axial compressive, external rotatory, and valgus forces applied to the elbow38,47. A varus extension mechanism has also been proposed32. The lesion leading to this pattern of instability is reported to be a disruption of the ulnar part of the lateral collateral ligament of the elbow30,31,36,42. This structure has been noted by some27,29,37 to extend from the lateral humeral epicondyle to the supinator tubercle of the ulna superficial to the annular ligament. However, the identification of the ulnar part of the lateral collateral ligament has varied in previous anatomical studies26,27,29,30,37, and the descriptions of the origins and insertions of the annular and lateral ligaments of the elbow have varied considerably in the literature6,7,11,13,14,25,39,45,46.

The present study defined the primary restraint to posterolateral rotatory instability of the elbow as the combination of the lateral collateral and annular ligaments, which coalesce to insert broadly over a two-centimeter area on the proximal aspect of the ulna. This arrangement was previously described by Martin25 as well as by other authors10,12,13,22,33,49,51. The supinator tendon, which attaches to the ulna and becomes confluent with the lateral collateral ligament toward its humeral origin, reinforces this structure. The present study did not identify a thin band of ligament spanning from the lateral epicondyle to the ulna, independent of the annular ligament, that provided the primary stability of the lateral aspect of the elbow. In fact, in the cutting sequence in Group II, sectioning of the inferior fibers of the lateral collateral ligament inferior to the axis of rotation of the elbow, which included the fibers previously identified as the ulnar part of the lateral collateral ligament, resulted in only a mean of 15 per cent of the total rotatory motion of the elbow. Furthermore, in Group III, division of all ligamentous attachments to the ulna resulted in only a mean of 11 per cent of total lateral rotatory motion.

These sequences support the concept of additional stabilizers of the lateral aspect of the elbow. The principal secondary restraints of the lateral aspect of the elbow consist of the extensor muscles with their fascial bands and intermuscular septa. The extensor muscles connect the dorsal aspect of the forearm with the lateral epicondyle. In supination, they serve to support the forearm unit independently and prevent it, by virtue of their course alone, from laterally rotating away from the humerus. The intermuscular septum between the extensor digitorum communis and the extensor digiti quinti adds an additional unyielding restraint to subluxation of the lateral aspect of the elbow. This septum tightens when the forearm is in supination and was found, with the muscles, to play an independent role in the stability of the elbow in Group III. When the septum was sectioned with all ulnar attachments released, rotatory motion of the elbow increased from a mean of 23 per cent to a mean of 53 per cent of total rotatory displacement.

Of all of the extensors, the stout fascial band of the extensor carpi ulnaris, seen in anatomical illustrations11,43, has the best mechanical advantage in resisting rotatory instability because of its course. It originates on the most inferior aspect of the lateral epicondyle and inserts onto the ulna approximately five centimeters distal to the center of the radial head. Sectioning of this fascial band alone led to a mean of only 5 per cent of total lateral rotatory motion of the elbow. However, in combination with the anterior extensor muscles and septa, this structure can provide most of the support to the lateral aspect of the elbow, as documented in Group IV.

The importance of muscular contributions to stability of the elbow was documented by Josefsson et al.20,21, whose operative explorations of simple dislocations of the elbow revealed complete disruption of the medial and lateral collateral ligaments in every case. The extent of the instability of the elbow documented at the operations appeared to have a direct association with the amount of muscular damage at the medial and lateral epicondyles. While we examined only the static contribution of the muscles in cadavera, their dynamic effect could add considerably to stability of the lateral aspect of the elbow. This is suggested by the reported observation of increased instability when a dislocated elbow is examined with the patient under anesthesia20,21. In addition, although our experimental protocol required sectioning of the anconeus, that structure too may provide a dynamic role in stability of the lateral aspect of the elbow, as previously suggested in electrical studies of this muscle3,40,50.

On the basis of the data from this study, we can draw certain conclusions regarding the underlying pathological anatomy involved in posterolateral rotatory instability of the elbow. In several clinical reports of rotatory instability, lateral roentgenograms showed most of the radial head projecting well distal to the inferior aspect of the capitellum5,32,36. In our experimental model, more than 60 per cent of total rotatory displacement of the elbow was required to document posterior displacement of the radial head (the anterior aspect of the radial head aligned with the inferior half of the capitellum). This suggests that damage of more than one structure is necessary to have a substantial amount of lateral instability of the elbow. Such a lesion involves attenuation or avulsion of both the ligamentous and the muscular origins from the lateral epicondyle. This pattern of injury has been commonly reported in unstable elbows treated operatively8,9,20,22,31,34. It is also consistent with our experience with four patients whom we managed operatively for acute traumatic posterolateral instability. These patients were found to have disruption of all of the soft tissues from the lateral epicondyle.

The present study has clinical relevance for the treatment of post-traumatic lateral instability of the elbow as well as other disorders about the elbow. It is clear that posterolateral rotation of the forearm from the humerus is reduced by pronation of the forearm31,35,36,38. In the present study, posterolateral instability spontaneously reduced with the cadaveric forearm in pronation, even when all of the lateral restraints had been sectioned. This suggests that patients who have an acute lateral disruption in which the radial head is subluxated inferiorly and the ulnohumeral joint is widened on the lateral roentgenogram may best be managed with a hinged brace with the forearm held in pronation. If operative intervention is chosen, immobilization of the elbow and forearm in this position protects the lateral repair or reconstruction32. Some simple dislocations of the elbow may fall into this category and should be evaluated with a lateral roentgenogram made with the forearm in supination after reduction.

The importance of the soft-tissue structures originating at the lateral epicondyle has relevance with respect to the operative tactics involved in débridement of the lateral aspect of the elbow for recalcitrant lateral epicondylitis. A subset of patients who have continued pain in the elbow after such débridement have subtle evidence of posterolateral instability28,32. This apparently results from overly extensive débridement of the origins of the collateral and extensor muscles off the lateral epicondyle. We presently debride only the tissues anterior to the palpable septum of the extensor digitorum communis and extensor digiti quinti at the middle of the axis of the epicondyle. This preserves the posterior fibers of the lateral collateral ligament and the extensor muscle origins.

The findings of this study may also have implications for post-traumatic excision of the radial head. With use of the common Kocher approach16, dissection through the interval between the anconeus and extensor carpi ulnaris muscles should be kept in line with the fibers of the extensor carpi ulnaris and not the axis of the forearm. In this way, the important extensor carpi ulnaris fascial band is not violated. When proximal extension of this incision is deemed necessary, it must be kept inferior to the epicondyle and not course anteriorly2, which would threaten the integrity of the lateral tendinous and ligamentous origins. As the combination of the annular and lateral collateral ligaments entirely covers the radial head, excision of the radial head necessitates violation of part of this lateral ligament complex. Theoretically, an incision placed slightly anterior to the center of the radial head and only carried as distal as necessary would leave a portion of the inferior collateral connection to the ulna intact. Careful repair of these fibers also seems important.

Finally, on the basis of the data obtained in this study, we have modified our approach to soft-tissue and capsular release for post-traumatic contracture of the elbow18. When radical débridement of a joint is not necessary, we now preserve the lateral collateral origin on the epicondyle. In this way, no postoperative protection of the lateral ligamentous structures is needed in the rehabilitation phase.


   Footnotes
 
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

{dagger}Rush-Presbyterian-St. Luke's Medical Center, 1725 West Harrison Street, Suite 1063, Chicago, Illinois 60612.

{ddagger}The Indiana Hand Center, 8501 Harcourt Road, Indianapolis, Indiana 46260.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. An, K.-N., and Morrey, B. F.:Biomechanics of the elbow. In The Elbow and Its Disorders, edited by B. F. Morrey. Ed. 2, pp. 53-73. Philadelphia, W. B. Saunders, 1993.
  2. Banks, S.W., and Laufman, H.: An Atlas of Surgical Exposures of the Extremities. Ed. 2, pp. 121-129. Philadelphia, W. B. Saunders, 1987.
  3. Basmajian, J. V., and |and |Griffin, W. R., Jr.: Function of anconeus muscle. An electromyographic study. J. Bone and Joint Surg., 54-A: 1712-1714, Dec. 1972.[Abstract/Free Full Text]
  4. Berquist, T. H.: Diagnostic radiographic techniques of the elbow. In The Elbow and Its Disorders, edited by B. F. Morrey. Ed. 2, pp. 98-119. Philadelphia, W. B. Saunders, 1993.
  5. Burgess, R. C., and |and |Sprague, H. H.: Post-traumatic posterior radial head subluxation. Two case reports. Clin. Orthop., 186: 192-194, 1984.
  6. Celli, L.: The Elbow: Traumatic Lesions, pp. 13-15. New York, Springer, 1991.
  7. Crouch, J. E.: Functional Human Anatomy. Ed. 4, pp. 147-151. Philadelphia, Lea and Febiger, 1985.
  8. Doria, A.; Gil, E.; Delgado, E.; and |and |Alonso-Llames, M.: Recurrent dislocation of the elbow. Internat. Orthop., 14: 41-55, 1990.[Medline]
  9. Dürig, N.; Müller, W.; Rüedi, T. P.; and |and |Gauer, E. F.: The operative treatment of elbow dislocation in the adult. J. Bone and Joint Surg., 61-A: 239-244, March 1979.[Abstract/Free Full Text]
  10. Gardner, E.; Gray, D. J.; and O'Rahilly, R.: Anatomy: a Regional Study of Human Structure. Ed. 4, pp. 128-130. Philadelphia, W. B. Saunders, 1975.
  11. Grant's Atlas of Anatomy, by Regions: Ed. 6. Baltimore, Williams and Wilkins, 1972.
  12. Gray's Anatomy: British ed. 36, pp. 461-463. Edited by P. L. Williams and R. Warwick. Philadelphia, W. B. Saunders, 1980.
  13. Gray's Anatomy of the Human Body: Ed. 20, edited by W. H. Lewis. Philadelphia, Lea and Febiger, 1918.
  14. Hamilton, W. J. [editor]: Textbook of Human Anatomy, pp. 186-187. New York, St. Martin's Press, 1956.
  15. Hollinshead, W. H.: Anatomy for Surgeons: Volume 3. The Back and Limbs. Ed. 2, pp. 379-382. New York, Hoeber Medical Division, Harper and Row, 1969.
  16. Hoppenfeld, S., and deBoer, P.: Surgical Exposures in Orthopaedics. The Anatomic Approach, pp. 97-101. Philadelphia, J. B. Lippincott, 1984.
  17. Hotchkiss, R. N., and |and |Weiland, A. J.: Valgus stability of the elbow. J. Orthop. Res., 5: 372-377, 1987.[Medline]
  18. Husband, J. B., and |and |Hastings, H., II: The lateral approach for operative release of post-traumatic contracture of the elbow. J. Bone and Joint Surg., 72-A: 1353-1358, Oct. 1990.[Abstract/Free Full Text]
  19. Johansson, O.: Capsular and ligament injuries of the elbow joint: a clinical and arthrographic study. Acta Chir. Scandinavica, Supplementum 287: 1962.
  20. Josefsson, P. O.; Johnell, O.; and |and |Wendeberg, B.: Ligamentous injuries in dislocations of the elbow joint. Clin. Orthop., 221: 221-225, 1987.
  21. Josefsson, P. O.; Gentz, C.-F.; Johnell, O.; and |and |Wendeberg, B.: Surgical versus non-surgical treatment of ligamentous injuries following dislocation of the elbow joint. A prospective randomized study. J. Bone and Joint Surg., 69-A: 605-608, April 1987.[Abstract/Free Full Text]
  22. Josefsson, P. O.; Gentz, C. F.; Johnell, O.; and |and |Wendeberg, B.: Dislocations of the elbow and intraarticular fractures. Clin. Orthop., 246: 126-130, 1989.
  23. Langman, J., and Woerdeman, M. W.: Atlas of Medical Anatomy. Philadelphia, W. B. Saunders, 1978.
  24. Last, R. J.: Anatomy, Regional and Applied. Ed. 6, pp. 77-78. New York, Churchill Livingstone, 1978.
  25. Martin, B. F.: The annular ligament of the superior radio-ulnar joint. J. Anat., 92: 473-482, 1958.[Medline]
  26. Morrey, B. F.: Anatomy of the elbow joint. In The Elbow and Its Disorders, pp. 20-22. Edited by B. F. Morrey. Philadelphia, W. B. Saunders, 1985.
  27. Morrey, B. F.: Applied anatomy and biomechanics of the elbow joint. In Instructional Course Lectures, The American Academy of Orthopaedic Surgeons. Vol. 35, pp. 59-68. St. Louis, C. V. Mosby, 1986.
  28. Morrey, B. F.: Re-operation for failed tennis elbow surgery. J. Shoulder and Elbow Surg., 1: 47-49, 1992.
  29. Morrey, B. F.: Anatomy of the elbow joint. In The Elbow and Its Disorders, edited by B. F. Morrey. Ed. 2, pp. 29-32. Philadelphia, W. B. Saunders, 1993.
  30. Morrey, B. F., and |and |An, K.-N.: Functional anatomy of the ligaments of the elbow. Clin. Orthop., 201: 84-90, 1985.
  31. Morrey, B. F., and O'Driscoll, S. W.: Lateral collateral ligament injury. In The Elbow and Its Disorders, edited by B. F. Morrey. Ed. 2, pp. 573-580. Philadelphia, W. B. Saunders, 1993.
  32. Nestor, B. J.; O'Driscoll, S. W.; and |and |Morrey, B. F.: Ligamentous reconstruction for posterolateral rotatory instability of the elbow. J. Bone and Joint Surg., 74-A: 1235-1241, Sept. 1992.[Abstract/Free Full Text]
  33. Netter, F. H.: The Ciba Collection of Medical Illustrations. Volume 8. Musculoskeletal System. Part I. Anatomy, Physiology and Metabolic Disorders. Summit, New Jersey, Ciba-Geigy, 1987.
  34. Norwood, L. A.; Shook, J. A.; and |and |Andrews, J. R: Acute medial elbow ruptures. Am. J. Sports Med., 9: 16-19, 1981.[Abstract/Free Full Text]
  35. O'Driscoll, S. W.: Classification and spectrum of elbow instability: recurrent instability. In The Elbow and Its Disorders, edited by B. F. Morrey. Ed. 2, pp. 453-463. Philadelphia, W. B. Saunders, 1993.
  36. O'Driscoll, S. W.; Bell, D. F.; and |and |Morrey, B. F.: Posterolateral rotatory instability of the elbow. J. Bone and Joint Surg., 73-A: 440-446, March 1991.[Abstract/Free Full Text]
  37. O'Driscoll, S. W.; Horii, E.; Morrey, B. F.; and |and |Carmichael, S. W.: Anatomy of the ulnar part of the lateral collateral ligament of the elbow. Clin. Anat., 5: 296-303, 1992.
  38. O'Driscoll, S. W.; Morrey, B. F.; Korinek, S.; and |and |An, K.-N.: Elbow subluxation and dislocation. A spectrum of instability. Clin. Orthop., 280: 186-197, 1992.
  39. Ogilvie, W. H.: Discussion on minor injuries of the elbow-joint. Proc. Roy. Soc. Med., 23: 306-330, 1930.
  40. Pauly, J. E.; Rushing, J. L.; and |and |Scheving, L. E.: An electromyographic study of some muscles crossing the elbow joint. Anat. Rec., 159: 47-53, 1967.[Medline]
  41. Piersol, G. A.: Human Anatomy: Including Structure and Development and Practical Considerations. Ed. 4, vol. 1, pp. 302-306. Philadelphia, J. B. Lippincott, 1913.
  42. Regan, W. D.; Korinek, S. L.; Morrey, B. F.; and |and |An, K.-N.: Biomechanical study of ligaments around the elbow joint. Clin. Orthop., 271: 170-179, 1991.
  43. Rohen, J. W., Yokochi, C.: Color Atlas of Anatomy. A Photographic Study of the Human Body. New York, Igaku-Shoin, 1983.
  44. Romanes, G. J.: Cunningham's Manual of Practical Anatomy, Upper and Lower Limbs. Ed. 13, vol. 1, pp. 117-118. London, Oxford University Press, 1966.
  45. Schaeffer, J. P.: Morris' Human Anatomy: a Complete Systematic Treatise. Ed. 11, pp. 334-335. New York, Blakiston, 1953.
  46. Schwab, G. H.; Bennett, J. B.; Woods, G. W.; and |and |Tullos, H. S.: Biomechanics of elbow instability: the role of the medial collateral ligament. Clin. Orthop., 146: 42-52, 1980.
  47. Sojbjerg, J. O.; Helmig, P.; and |and |Kjaersgaard-Andersen, P.: Dislocation of the elbow: an experimental study of the ligamentous injuries. Orthopedics, 12: 461-463, 1989.[Medline]
  48. Sojbjerg, J. O.; Ovesen, J.; and |and |Nielsen, S.: Experimental elbow instability after transection of the medial collateral ligament. Clin. Orthop., 218: 186-190, 1987.
  49. Spalteholz, W. Hand-Atlas of Human Anatomy, pp. 235-236. Amsterdam, Scheltema and Holkema, 1959.
  50. Travill, A. A.: Electromyographic study of the extensor apparatus of the forearm. Anat. Rec., 144: 373-376, 1962.[Medline]
  51. Wadsworth, T. G. [editor]: The Elbow. pp. 8-9. New York, Churchill Livingstone, 1982.

Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Facebook Facebook   Add to Technorati Technorati   Add to Twitter Twitter    What's this?


This article has been cited by other articles:


Home page
 Am. J. Roentgenol.Home page
H. T. Sanal, L. Chen, P. Haghighi, D. J. Trudell, and D. L. Resnick
Annular Ligament of the Elbow: MR Arthrography Appearance With Anatomic and Histologic Correlation
Am. J. Roentgenol., August 1, 2009; 193(2): W122 - W126.
[Abstract] [Full Text] [PDF]

Home page
 JBJSHome page
H. Moritomo, T. Murase, S. Arimitsu, K. Oka, H. Yoshikawa, and K. Sugamoto
The in Vivo Isometric Point of the Lateral Ligament of the Elbow
J. Bone Joint Surg. Am., September 1, 2007; 89(9): 2011 - 2017.
[Abstract] [Full Text] [PDF]

Home page
 Emerg. Med. J.Home page
D Sunderamoorthy, A Smith, and D A Woods
Recurrent elbow dislocation--an uncommon presentation
Emerg. Med. J., September 1, 2005; 22(9): 667 - 669.
[Abstract] [Full Text] [PDF]

Home page
 JBJSHome page
D. M. Kalainov and M. S. Cohen
Posterolateral Rotatory Instability of the Elbow in Association with Lateral Epicondylitis. A Report of Three Cases
J. Bone Joint Surg. Am., May 1, 2005; 87(5): 1120 - 1125.
[Full Text] [PDF]

Home page
 J Bone Joint Surg BrHome page
J. Sanchez-Sotelo, B. F. Morrey, and S. W. O'Driscoll
Ligamentous repair and reconstruction for posterolateral rotatory instability of the elbow
J Bone Joint Surg Br, January 1, 2005; 87-B(1): 54 - 61.
[Abstract] [Full Text] [PDF]

Home page
 Am J Sports MedHome page
M. Bozkurt, H. I. Acar, N. Apaydin, G. Leblebicioglu, A. Elhan, I. Tekdemir, and E. Tonuk
The Annular Ligament: An Anatomical Study
Am. J. Sports Med., January 1, 2005; 33(1): 114 - 118.
[Abstract] [Full Text] [PDF]

Home page
 J Am Acad Orthop SurgHome page
J. A. Mehta and G. I. Bain
Posterolateral Rotatory Instability of the Elbow
J. Am. Acad. Ortho. Surg., November 1, 2004; 12(6): 405 - 415.
[Abstract] [Full Text] [PDF]

Home page
 JBJSHome page
M. J. Beuerlein, J. T. Reid, E. H. Schemitsch, and M. D. McKee
Effect of Distal Humeral Varus Deformity on Strain in the Lateral Ulnar Collateral Ligament and Ulnohumeral Joint Stability
J. Bone Joint Surg. Am., October 1, 2004; 86(10): 2235 - 2242.
[Abstract] [Full Text] [PDF]

Home page
 JBJSHome page
A. G. Schneeberger, M. M. Sadowski, and H. A.C. Jacob
Coronoid Process and Radial Head as Posterolateral Rotatory Stabilizers of the Elbow
J. Bone Joint Surg. Am., May 1, 2004; 86(5): 975 - 982.
[Abstract] [Full Text] [PDF]

Home page
 JBJSHome page
P. Rosell, J. Clasper, D. Ring, J. B. Jupiter, and J. Zilberfarb
Roles of the Medial Collateral Ligament and the Coronoid in Elbow Stability
J. Bone Joint Surg. Am., March 11, 2003; 85(3): 568 - 569.
[Full Text] [PDF]

Home page
 JBJSHome page
C. E. Dunning, Z. D.S. Zarzour, S. D. Patterson, J. A. Johnson, and G. J.W. King
Ligamentous Stabilizers Against Posterolateral Rotatory Instability of the Elbow
J. Bone Joint Surg. Am., December 1, 2001; 83(12): 1823 - 1828.
[Abstract] [Full Text] [PDF]

Home page
 J Am Acad Orthop SurgHome page
D. J. Hak and G. J. Golladay
Olecranon Fractures: Treatment Options
J. Am. Acad. Ortho. Surg., July 1, 2000; 8(4): 266 - 275.
[Abstract] [Full Text] [PDF]

Home page
 JBJSHome page
S. W. O'Driscoll, J. B. Jupiter, G. J. W. King, R. N. Hotchkiss, and B. F. Morrey
The Unstable Elbow*{{dagger}}
J. Bone Joint Surg. Am., May 1, 2000; 82(5): 724 - 724.
[Full Text]

Home page
 JBJSHome page
D. RING, J. B. JUPITER, and N. S. SIMPSON
Monteggia Fractures in Adults
J. Bone Joint Surg. Am., December 1, 1998; 80(12): 1733 - 44.
[Abstract] [Full Text]

Home page
 JBJSHome page
D. RING and J. B. JUPITER
Current Concepts Review - Fracture-Dislocation of the Elbow
J. Bone Joint Surg. Am., April 1, 1998; 80(4): 566 - 80.
[Full Text]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF) Free
Right arrow Letters to the Editor: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when Letters to the Editor are posted
Right arrow Alert me if a correction is posted
Services
Right arrow E-mail this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My File Cabinet
Right arrow Download to citation manager
Right arrow Rights and Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by COHEN, M. S.
Right arrow Articles by HASTINGS II, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by COHEN, M. S.
Right arrow Articles by HASTINGS II, H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us   Add to Facebook   Add to Technorati   Add to Twitter  
What's this?