JBJS | Posterolateral Dislocation of the Elbow Joint : Relationship to Medial Instability*

The Journal of Bone & Joint Surgery, Volume 82, Issue 4

Articles | April 01, 2000

Posterolateral Dislocation of the Elbow Joint : Relationship to Medial Instability*

D. Eygendaal, M.D.†; S. H. M. Verdegaal, M.D.†; W. R. Obermann, M.D, PH.D.†; A. B. van Vugt, M.D., PH.D.‡; R. G. Pöll, M.D., PH.D.†; P. M. Rozing, M.D., PH.D.†

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Investigation performed at Leiden University Medical Center, Leiden, The Netherlands
*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.
†Departments of Orthopedics (D. E., S. H. M. V., R. G. P., and P. M. R.) and Radiology (W. R. O.), Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, The Netherlands. E-mail address for D. Eygendaal: d.eygendaal@wxs.nl.
‡Department of Traumatology, Academic Hospital Rotterdam Dijkzigt, Dr. Molewaterplein 40, 3013 GD Rotterdam, The Netherlands.

The Journal of Bone & Joint Surgery. 2000; 82:555-555

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Abstract

Background: Dislocation of the elbow joint is the second most common dislocation in the upper extremity, dislocation of the shoulder being the most common. It has been reported that uncomplicated dislocation of the elbow joint may be associated with a decreased range of motion, degenerative changes in the elbow joint, ectopic calcification, or neurological deficits. As the medial collateral ligament complex can be completely disrupted during dislocation, we evaluated the association between the long-term results of treatment of simple posterolateral dislocation of the elbow and the presence of persistent medial or valgus elbow instability.

Methods: Fifty patients who had a mean age of thirty-three years (range, eighteen to fifty-eight years) had closed reduction of a posterolateral dislocation of the elbow without associated fractures. The extremity was immobilized in an above-the-elbow plaster cast for three weeks. After a mean duration of follow-up of nine years (range, six to thirteen years), forty-one patients were evaluated with an interview, a physical examination, and radiographs made while a valgus load was applied to the elbow.

Results: The average score according to the system of The Hospital for Special Surgery was 91 points (range, 49 to 100 points), and thirty-one patients described their elbow function as good or excellent. Twenty-four patients had evidence of medial instability on radiographs made while a valgus load was applied to the elbow. Twenty-one patients had signs of degeneration of the joint, and twenty-five patients had ectopic ossification. Magnetic resonance imaging combined with arthrography was performed for the first twenty patients; eight had evidence of rupture of the medial collateral ligament, seven had generalized degenerative changes of the cartilage, and four had a chondral defect of the capitellum. (The study could not be completed for the remaining patient.) Medial instability on radiographs was correlated with signs of degeneration (p = 0.001), ectopic ossification (p = 0.01), a worse score according to the system of The Hospital for Special Surgery (p = 0.002), and persistent pain (p = 0.04).

Conclusions: Posterolateral dislocation of the elbow joint can lead to persistent valgus instability that is associated with a worse overall clinical and radiographic result.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

The elbow joint is the second most commonly dislocated joint of the upper extremity, the shoulder being the most common. Josefsson and Nilsson⁹ evaluated the frequency of dislocation of the elbow on the basis of age and gender in a population of 245,000 persons in the city of Malmö, Sweden, over a period of twelve years and reported an annual incidence of six dislocations per 100,000 persons. It has been reported that dislocation of the elbow most frequently occurs in a posterolateral direction². The medial ligamentous complex can be partially or completely ruptured during posterolateral dislocation, resulting in persistent medial or valgus instability.

The medial collateral ligament, or medial ulnar collateral ligament, consisting of anterior, posterior, and transverse parts, provides valgus stability to the elbow joint. The anterior part of the medial collateral ligament has been shown to be the most important soft-tissue constraint to valgus force across the elbow^6,15,16,25. Clinical observations and biomechanical studies have shown rupture of the medial collateral ligament in association with all posterolateral dislocations of the elbow joint^{1,10,11,23,26}. Some authors have observed valgus instability during physical examination performed immediately after dislocation of the elbow^{8,10,12,14,20}.

Josefsson et al.⁸ reported that, after posterolateral dislocation of the elbow, approximately 50 percent of fifty-two patients had some loss of extension, degenerative changes in the joint, ectopic calcification, or neurological changes. None of these residual signs or symptoms has ever been correlated with the stage and extent of ligamentous damage or the degree of persistent medial instability. Radiographs made while a valgus load is applied to the elbow and magnetic resonance arthrography of the elbow have made it possible to distinguish among large or complete tears of the medial collateral ligament complex, small partial tears, and intact ligaments^18,22,24.

In the present study, we evaluated the relationship between the long-term outcome following posterolateral dislocation of the elbow and the presence of persistent medial instability secondary to rupture of the anterior part of the medial collateral ligament. Dynamic radiographs made with the elbow under valgus load and magnetic resonance imaging were used to establish the integrity of the anterior part of the medial collateral ligament.

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Fig. 1:: Photograph showing the device that was used to place the elbow under valgus load while dynamic radiographs were made. The wrist is fixed in supination between two rollerbars, the elbow is held in 25 degrees of flexion, and the arm is held in 65 degrees of abduction. An L-shaped bar supports the shoulder anteriorly.

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Fig. 2:: Anteroposterior radiographs made with the elbow under valgus load (left) and in the unloaded condition (right). The distance (d) (arrow, left side of figure) between the most distal point on the curved contour of the medial condyle and the ulnar coronoid process was measured in the unloaded situation (d0) and with the elbow under 1.5 newton-meters of valgus load (d1.5). The increase in this distance (d1.5 - d0) was recorded for both the injured and the uninjured side. Medial instability was evaluated by subtracting the increase on the uninjured side from that on the injured side. In this patient, medial instability measured 3.2 millimeters and the elbow was classified as unstable.

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Fig. 3:: Magnetic resonance arthrogram showing a midsubstance rupture of the medial collateral ligament (arrow), indicated by the leakage of contrast medium

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

Between January 1985 and December 1992, fifty patients who had a mean age of thirty-three years (range, eighteen to fifty-eight years) were managed with closed reduction of a traumatic posterolateral dislocation of the elbow. Patients were eligible for the present study if they had no associated fractures, were at least eighteen years old, had no history of operations or fractures involving the elbow, and did not have rheumatoid arthritis. Forty-one patients were available for evaluation after a mean duration of follow-up of nine years (range, six to thirteen years). All of the subjects gave informed consent, and the institutional review board approved the study.

The study group included seventeen women and twenty-four men who had a mean age of forty-two years (range, twenty-four to sixty-nine years) at the time of the evaluation. The left elbow was involved in twenty-three patients and the right, in eighteen; twenty-two patients had involvement of the dominant limb. Sixteen dislocations occurred during sports activities; seventeen, during activities at home; and eight, in a traffic accident. At the time of the injury, nineteen patients had a sedentary job, nine had a physically demanding job, ten were homemakers, and three were unemployed.

All patients were seen immediately after the injury. The elbow was reduced without general anesthesia. The extremity was immobilized in an above-the-elbow cast for three weeks. At that time, active and passive exercises were started under the supervision of a physiotherapist; the exercises were continued for three months. After three weeks, activities were not specifically restricted and the patient could resume full activity to the best of his or her ability and tolerance. All patients were seen at three weeks, three months, and six months. It usually took at least six months for a patient to gain maximum motion and strength.

Each patient was carefully questioned with regard to the level of pain or discomfort during daily, job-related, and sports activities; any change in job-related and sports activities; and their subjective evaluation of elbow function. The Hospital for Special Surgery questionnaire⁶ was completed, and functional status was assessed with use of the Mayo Clinic performance index¹⁷. Physical examination included a comparison of the ranges of motion of the involved and contralateral elbows, the valgus stability test as described by Jobe et al.⁷, and the pivot-shift test for the detection of posterolateral rotatory instability as described by O'Driscoll et al.¹⁹. This last test involves supination of the forearm and application of a valgus moment and an axial compression force while the elbow is moved from full flexion to full extension. Neurological examination included testing of sensation to pinprick and two-point discrimination as well as evaluation of the motor function of the ulnar, median, and radial nerves. Electrodiagnostic studies were performed if there were any abnormal neurological findings.

Anteroposterior and lateral radiographs of both elbow joints were examined by two independent observers for evidence of ectopic ossification and degenerative changes. Ectopic ossification was classified, according to the system of Broberg and Morrey³, as an osseous exostosis or as soft-tissue ossification of a ligament, capsule, or muscle. Degenerative changes were classified as grade 0 (no changes), grade 1 (slight narrowing of the joint space with small osteophytes), grade 2 (moderate narrowing of the joint space, osteophytes, and subchondral sclerosis), and grade 3 (severe narrowing of the joint space, large osteophytes, subchondral sclerosis, and cystic deformation).

Standardized dynamic radiographs of both elbows were made with the assistance of the TELOS stress device (Austin and Associates, Fallston, Maryland) (Fig. 1). The patient was seated, with the upper extremity positioned in the device in slight supination and with the elbow flexed to 25 degrees; the extremity was stabilized at the axilla and the distal aspect of the forearm. Anteroposterior radiographs of the elbow then were made, first without stress and then with 1.5 newton-meters of pressure applied to the lateral side of the elbow. The force was applied gradually in a lateral-to-medial direction with use of the screw-threaded shaft of the TELOS device and was monitored on a light-emitting digital readout²². The distance (d) between the most distal point on the curved contour of the medial condyle and the ulnar coronoid process then was measured in millimeters, by two independent observers, on the radiographs made without load (d0) and with the elbow under 1.5 newton-meters of valgus load (d1.5) (Fig. 2). The increase in this distance (d1.5 - d0) was recorded for both the injured and the uninjured side. Medial instability was evaluated by subtracting the increase on the uninjured side from that on the injured side. On the basis of cadaveric studies, the elbows were graded as stable (a difference of 0.0 to 0.4 millimeter), partially unstable (0.5 to 2.9 millimeters), unstable (3.0 to 5.9 millimeters), or subluxated (6.0 millimeters or more)^3,21.

Magnetic resonance imaging combined with arthrography was performed for the first twenty patients to visualize the collateral ligament complex and articular cartilage. These studies were analyzed by two independent radiologists.

Statistical analysis was performed with use of SPSS statistical software (SPSS, Chicago, Illinois). Correlation, assessed with use of Spearman's rank correlation coefficient, was graded as excellent (at least 0.91), good (0.71 to 0.90), moderate (0.51 to 0.70), fair (0.31 to 0.50), or poor (less than 0.31).

Results

Introduction | Materials and Methods | Results | Discussion | References

None of the forty-one patients had a redislocation of the injured elbow at the time of the latest follow-up evaluation. The average score according to the system of The Hospital for Special Surgery was 91 points (range, 49 to 100 points); two patients reported constant pain in the injured elbow, seventeen patients reported occasional pain, and the remaining patients reported no pain. Eleven patients had difficulties during sports activities; four, during physically demanding work activities; and thirteen, during activities of daily living. Three patients changed their job, and eight changed their sports activities. Thirteen patients described their elbow function as excellent; eighteen, as good; nine, as moderate; and one, as poor. Medial instability, as demonstrated on radiographs, had a fair correlation with subjective function (p = 0.01), a fair correlation with persistent pain (p = 0.04), and a moderate correlation with a worse score according to the system of The Hospital for Special Surgery (p = 0.002).

Eight patients had a decrease in flexion of 5 to 10 degrees and twenty-three had a decrease in extension of 5 to 10 degrees in comparison with the uninjured side. One patient lacked the last 30 degrees of pronation and 40 degrees of supination. Fifteen patients had moderate valgus instability of the elbow on the test described by Jobe et al.⁷, and three had severe instability. Six patients had a positive pivot-shift test, suggestive of posterolateral rotatory insufficiency. Nine patients had a positive Tinel sign over the cubital tunnel, two had decreased sensitivity to pinprick along the distribution of the ulnar nerve, and one was unable to abduct the fifth digit. Two of the nine patients who had a positive Tinel sign had abnormalities related to the ulnar nerve on electrodiagnostic studies. All nine patients who had a positive Tinel sign had evidence of medial instability on dynamic radiographs (p = 0.01).

The Mayo Clinic performance index for the elbow was graded as excellent for twenty-five patients, good for twelve, and moderate for four. Twenty-one patients had degenerative changes in the injured elbow; the changes were classified as grade 1 in twelve patients and as grade 2 in nine. One of the nine patients with grade-2 changes in the injured elbow also had grade-1 changes in the uninjured elbow. Twenty-five patients had ectopic ossification; the ossification was classified as an osseous exostosis in six patients and as soft-tissue ossification in nineteen. Twenty-four patients had evidence of medial instability on dynamic radiographs made while a valgus load was applied to the elbow; eighteen patients had partial instability, four had complete instability, and two had subluxation. Medial instability showed a good correlation with arthrosis (p = 0.001) and a moderate correlation with ectopic ossification (p = 0.01). Arthrosis had a fair correlation with The Hospital for Special Surgery score (p = 0.02) and a fair correlation with pain (p = 0.03). Ectopic ossification had a poor correlation with pain (p = 0.09) and a fair correlation with The Hospital for Special Surgery score (p = 0.06).

Magnetic resonance imaging combined with arthrography was performed for our first twenty patients. The study could not be completed for one patient, who was claustrophobic. Eleven of the remaining nineteen patients had a normal medial collateral ligament; in these eleven patients, the anterior and posterior parts of the ligament could not be distinguished as separate structures. Five of the eleven patients had stability of the elbow on dynamic radiographs, and six had medial instability. Eight of the nineteen patients had a rupture of the medial collateral ligament; five of the eight patients had a midsubstance rupture of the medial collateral ligament, and three had an avulsion of the humeral insertion of the ligament (Fig. 3). All eight patients had medial instability on dynamic radiographs. Four patients had a chondral defect of the capitellum and seven had generalized degenerative changes of the cartilage; all eleven had evidence of medial instability on dynamic radiographs. Four patients had intra-articular loose bodies.

Discussion

Introduction | Materials and Methods | Results | Discussion | References

Posterolateral dislocation of the elbow as a result of trauma is believed to occur in three sequential stages. O'Driscoll et al.¹⁹ believed that these stages progress from the lateral to the medial side of the elbow. In stage 1, the radial collateral ligament is disrupted; in stage 2, the other lateral structures and the anterior and posterior parts of the capsule are disrupted; and in stage 3, the medial ulnar collateral ligament is disrupted (either partially, with disruption of only the posterior part [stage 3-A], or completely, with disruption of the anterior part [stage 3-B]). Dislocation of the elbow occurs at the end of the final (third) stage. This mechanism of dislocation suggests that the elbow can be dislocated with or without disruption of the functional integrity of the joint, depending on the extent of ligamentous damage. However, there has been no attempt to classify dislocations on the basis of the extent of ligamentous damage.

One of us (D. E.) and colleagues⁴ performed a study on eight cadaveric elbows to determine the increase in the medial joint opening, three-dimensional angular displacement, and translation of the radial head after selective transection of the medial collateral ligament. Transection of the anterior fibers of the anterior part of the medial collateral ligament resulted in an increase in the medial joint opening of 0.8 millimeter, transection of the posterior fibers of the anterior part of the ligament resulted in an increase of 0.6 millimeter, transection of the entire anterior part of the ligament resulted in an increase of 2.7 millimeters, and transection of the entire ligament resulted in an increase of 5.9 millimeters. In the clinical situation, an increase of 5.9 millimeters would result in damage to the cartilage of the radial head.

Rijke et al.²², in a study of freshly embalmed cadaveric elbows, tested the validity of stress radiography for the evaluation of the medial collateral ligament. The examination was performed by sectioning the anterior part of the ligament into increments of 25 percent. The increase in the joint space was plotted against the amount of transection of the ligament. The increase in the joint space increased linearly with the amount of transection, from 0.2 millimeter when the ligament was intact to 2.8 millimeters at 100 percent transection. In the clinical portion of their study, Rijke et al. reported that stress radiographs revealed instability in seventeen of forty-two patients. At the time of operative intervention, all seventeen patients were found to have a rupture of the medial collateral ligament. The authors concluded that stress radiography made it possible to diagnose large and complete tears accurately as well as to distinguish among such tears, partial tears, and normal ligaments. Schwartz et al.²⁴ compared the findings of magnetic resonance arthrography with the intraoperative findings in forty patients. They reported that eighteen of nineteen complete medial collateral ligament tears and six of seven partial tears were diagnosed accurately with use of magnetic resonance arthrography. Nakanishi et al.¹⁸ found that the addition of arthrography to magnetic resonance imaging studies provided additional information compared with imaging studies alone.

Several authors have reported the long-term sequelae after simple dislocation. Josefsson et al.⁸ reported residual signs or symptoms in approximately 50 percent of fifty-two patients at a mean of twenty-four years after posterolateral dislocation of the elbow. No patient had residual neurological deficits, but nineteen had a decrease in the range of motion. Of the fifty patients who had a radiographic examination, nineteen had minimal degenerative changes and thirty-eight had evidence of periarticular ossification. Borris et al.² reported good-to-excellent results in twenty-three of thirty-four patients at a mean of eight years after a dislocation. No patient had a neurological deficit, but eighteen had an extension deficit of more than 10 degrees. Eight elbows were unstable, twenty-three had evidence of periarticular calcification, and one had signs of degeneration. Lansinger et al.¹² reported a good or excellent result in twenty-nine of thirty-four patients at a mean of five years after dislocation. Two patients had persistent sensory disturbances along the ulnar nerve, one had an injury to the brachial artery, and twenty had an extension deficit of more than 15 degrees.

In the present study, the left elbow was injured more frequently than the right; similar findings have been reported in the literature^8,11,13,21. The frequency of ectopic ossification was comparable with that reported in other studies^14,21; however, in our study, there was no association between ectopic ossification and the overall clinical result. Our findings regarding the loss of range of motion and the persistence of pain did not differ from those reported in other studies^14,21. Degenerative changes were more common in our study than in the study by Mehlhoff et al.¹⁴; however, the mean duration of follow-up in that study was only two years and ten months. Our results were comparable with those in the report by Josefsson et al.⁸, in which the mean duration of follow-up was twenty-four years.

Persistent medial instability after posterolateral dislocation of the elbow has been reported in the literature. Josefsson et al.⁸ found that eight of fifty-two elbows were unstable to manual stress at a mean of twenty-four years after posterolateral dislocation. Those authors did not classify valgus instability or determine if there was any relationship between the clinical results and the degenerative changes seen on the radiographs. Mehlhoff et al.¹⁴ stated that eighteen (35 percent) of fifty-two patients had pain with valgus-loading activites. In our study, medial instability of the elbow was associated with worse subjective functional ability, more pain, and signs of degeneration on radiographs and imaging studies.

It is possible that there was extensive ligamentous damage in our patients who had long-term valgus instability. Although imaging studies did not demonstrate all instances of ligamentous insufficiency, all of the elbows that were shown to have a ruptured or avulsed medial collateral ligament on imaging studies were unstable on dynamic radiographs made with the elbow subjected to stress. It should be noted that, although an old or partial rupture of the medial collateral ligament may be hard to visualize on imaging studies, such a rupture can still lead to instability on dynamic radiographs. It is important to identify a rupture of the medial collateral ligament after dislocation of the elbow because patients who have such a rupture have a higher risk of persistent valgus instability in the future than those who have an intact ligament. A radiograph made with the elbow under a valgus load seems to be the diagnostic tool of choice, although it may be painful for the patient immediately after the traumatic incident. Therefore, in the acute situation, such a radiograph should be made with the use of local anesthesia.

Additional treatment, possibly with a brace that is molded in slight varus and that permits flexion and extension of the elbow, may be necessary for an additional six weeks after the initial period of immobilization. This may prevent the development of long-term valgus instability and secondary degenerative changes, thereby improving the overall result after an isolated posterolateral dislocation of the elbow. Our study confirms the findings of other authors that persistent valgus instability of the elbow is one of the long-term sequelae of a posterolateral dislocation of the elbow and that such instability is associated with a worse overall result.

References

Introduction | Materials and Methods | Results | Discussion | References

Bennett, J. B.; Green, M. S.; and Tullos, H. S.: Surgical management of chronic medial elbow instability. Clin. Orthop., 278: 62-68, 1992.

Borris, L. C.; Lassen, M. R.; and Christensen, C. S.: Elbow dislocation in children and adults. A long-term follow-up of conservatively treated patients. Acta Orthop. Scandinavica, 58: 649-651, 1987.

Broberg, M. A., and Morrey, B. F.: Results of treatment of fracture-dislocations of the elbow. Clin. Orthop., 216: 109-119, 1987.

Eygendaal, D.; Olsen, B. S.; Jensen, S. L.; Seki, A.; and Söjbjerg, J. O.: Medial instability of the elbow joint; kinematics and clinical relevance. J. Shoulder and Elbow Surg., 8: 612-616, 1999.

Hotchkiss, R. N., and Weiland, A. J.: Valgus stability of the elbow. J. Orthop. Res., 5: 372-377, 1987.

Inglis, A. E., and Pellicci, P. M.: Total elbow replacement. J Bone Joint Surg, 62-A: 1252-1258, Dec. 1980.

Jobe, F. W.; Stark, H.; and Lombardo, S. J.: Reconstruction of the ulnar collateral ligament in athletes. J Bone Joint Surg, 68-A: 1158-1163, Oct. 1986.

Josefsson, P. O.; Johnell, O.; and Gentz, C. F.: Long-term sequelae of simple dislocation of the elbow. J Bone Joint Surg, 66-A: 927-930, July 1984.

Josefsson, P. O., and Nilsson, B. E.: Incidence of elbow dislocation. Acta Orthop. Scandinavica, 57: 537-538, 1986.

Josefsson, P. O.; Gentz, C.-F.; Johnell, O.; and Wendeberg, B.: Surgical versus non-surgical treatment of ligamentous injuries following dislocation of the elbow joint. A prospective randomized study. J Bone Joint Surg, 69-A: 605-608, April 1987.

Josefsson, P. O.; Johnell, O.; and Wendeberg, B.: Ligamentous injuries in dislocations of the elbow joint. Clin. Orthop., 221: 221-225, 1987.

Lansinger, O.; Karlsson, J.; Korner, L.; and Mare, K.: Dislocation of the elbow joint. Arch. Orthop. and Traumatic Surg., 102: 183-186, 1984.

Linscheid, R. L., and Wheeler, D. K.: Dislocation of the elbows. J. Am. Med. Assn., 194: 113-118, 1965.

Mehlhoff, T. L.; Noble, P. C.; Bennett, J. B.; and Tullos, H. S.: Simple dislocation of the elbow in the adult. Results after closed treatment. J Bone Joint Surg, 70-A: 244-249, Feb. 1988.

Morrey, B. F., and An, K.-N.: Functional anatomy of the ligaments of the elbow. Clin. Orthop., 201: 84-90, 1985.

Morrey, B. F.; Tanaka, S.; and An, K.-N.: Valgus stability of the elbow. A definition of primary and secondary constraints. Clin. Orthop., 265: 187-195, 1991.

Morrey, B. F., and Adams, R. A.: Semiconstrained arthroplasty for the treatment of rheumatoid arthritis of the elbow. J Bone Joint Surg, 74-A: 479-490, April 1992.

Nakanishi, K.; Masatomi, T.; Ochi, T.; Ishida, T.; Hori, S.; Ikezoe, J.; and Nakamura, H.: MR arthrography of elbow: evaluation of the ulnar collateral ligament of elbow. Skel. Radiol., 25: 629-634, 1996.

O'Driscoll, S. W.; Morrey, B. F.; Korinek, S.; and An, K. N.: Elbow subluxation and dislocation. A spectrum of instability. Clin. Orthop., 280: 186-197, 1992.

Osborne, G., and Cotterill, P.: Recurrent dislocation of the elbow. J Bone Joint Surg, 48-B(2): 340-346, 1966.

Protzman, R. R.: Dislocation of the elbow joint. J Bone Joint Surg, 60-A: 539-541, June 1978.

Rijke, A. M.; Goitz, H. T.; McCue, F. C.; Andrews, J. R.; and Berr, S. S.: Stress radiography of the medial elbow ligaments. Radiology, 191: 213-216, 1994.

Schwab, G. H.; Bennett, J. B.; Woods, G. W.; and Tullos, H. S.: Biomechanics of elbow instability: the role of the medial collateral ligament. Clin. Orthop., 146: 42-52, 1980.

Schwartz, M. L.; al-Zahrani, S.; Morwessel, R. M.; and Andrews, J. R.: Ulnar collateral ligament injury in the throwing athlete: evaluation with saline-enhanced MR arthrography. Radiology, 197: 297-299, 1995.

Söjbjerg, J. O.; Ovesen, J.; and Nielsen, S.: Experimental elbow instability after transection of the medial collateral ligament. Clin. Orthop., 218: 186-190, 1987.

Tullos, H. S.; Schwab, G.; Bennett, J. B.; and Woods, G. W.: Factors influencing elbow instability. In Instructional Course Lectures, American Academy of Orthopaedic Surgeons. Vol. 30, pp. 185-199. St. Louis, C. V. Mosby, 1981.

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