Arthroscopic Treatment of Posterolateral Elbow Impingement From Lateral Synovial Plicae in Throwing Athletes and Golfers

Arthroscopic Treatment of Posterolateral Elbow Impingement From Lateral Synovial Plicae in Throwing Athletes and Golfers David H. Kim,* MD, Ralph A. Gambardella, MD, Neal S. ElAttrache, MD, Lewis A. Yocum, MD, and Frank W. Jobe, MD From Huntington Beach Orthopedics and Sports Medicine, Huntington Beach, California, and the Kerlan-Jobe Orthopaedic Clinic, Los Angeles, California Background: Although elbow pain is common in throwing athletes and golfers, posterolateral impingement from a hypertrophic synovial plica is a rare but possibly underdiagnosed condition. Purpose: To evaluate the clinical results of arthroscopic treatment of symptomatic lateral elbow plicae in this athletic population. Study Design: Case series; Level of evidence, 4. Methods: Twelve patients, 9 male and 3 female, whose mean age was 21.6 years (range, 17-33 years), were reviewed. There were 7 baseball pitchers, 2 softball players, and 3 golfers. All patients had diagnosed isolated lateral elbow plica; none had lateral epicondylitis, instability, osteochondritis dissecans, arthritis, loose bodies, or nerve conditions. The mean time from onset of symptoms to treatment was 9.25 months (range, 3-24.5 months). At a mean follow-up of 33.8 months (range, 24-65.5 months), patients were evaluated with a questionnaire and examination, based on the American Shoulder and Elbow Surgeons standardized elbow assessment and previously reported elbow outcome score. Results: Posterolateral elbow pain was present in all patients. Fifty-eight percent (7 of 12 patients) complained of clicking or catching, whereas only 25% (3 of 12) experienced swelling or effusion. At elbow arthroscopy, a thickened synovial lateral plica was debrided in all cases. Ninety-two percent (11 of 12 patients) reported an excellent outcome with a mean elbow score of 92.5 points (maximum, 100 points). Return to competitive play averaged 4.8 months (range, 3-9.5 months). One patient with a fair outcome developed medial elbow instability that later required reconstructive surgery. Conclusion: Posterolateral elbow impingement from hypertrophic synovial plicae can cause significant pain and disability in throwing athletes and golfers. With careful diagnosis and exclusion of other elbow problems, treatment with arthroscopic debridement and focused rehabilitation is highly successful and allows these athletes to return to their previous level of play. Keywords: elbow arthroscopy; plica; throwing athlete; golfer Elbow pain is a common complaint in throwing athletes and golfers. Medial-sided elbow problems such as flexor/pronator strain, ulnar collateral ligament injury, ulnar nerve conditions, and medial epicondylitis are usually more common, but lateral elbow conditions such as lateral epicondylitis and osteochondritis dissecans can also occur. Sometimes lateral elbow pain can be *Address correspondence to David H. Kim, MD, 17742 Beach Blvd, Suite 245, Huntington Beach, CA 92647 (e-mail: dkimd@hotmail.com). Presented at the interim meeting of the AOSSM, Washington, DC, February 2005. No potential conflict of interest declared. The American Journal of Sports Medicine, Vol. 34, No. 3 DOI: 10.1177/0363546505281917 2006 American Orthopaedic Society for Sports Medicine associated with mechanical symptoms, such as snapping or catching, or the location of the pain is posterolateral and not along the lateral epicondyle or extensor tendon origin. In these more rare instances, these symptoms can be caused by a thickened or inflamed synovial plica, 1,2,5 much like medial parapatellar knee pain can sometimes be caused by a hypertrophic mediopatellar synovial plica. 9,10,14,15,17 It has been our observation that certain athletes who engage in repetitive activities of the elbow, such as throwing a ball or swinging a golf club, especially at a high competitive level, can be susceptible to this problem. The objective of this study was to evaluate the clinical results of throwing athletes and golfers with posterolateral elbow pain caused by a thickened, hypertrophic plica and treated with elbow arthroscopy and debridement. 438

Vol. 34, No. 3, 2006 Lateral Synovial Plicae in Throwing Athletes and Golfers 439 MATERIALS AND METHODS From April 1998 through April 2002, 166 cases of elbow arthroscopy were performed at our institution. Of these patients, 18 throwing athletes and golfers were noted to have a thickened synovial plica in conjunction with isolated posterolateral elbow pain. They were treated with arthroscopic debridement and resection of the thickened plica. Three patients could not be located, and 3 patients were excluded from this study because they demonstrated concurrent elbow abnormalities (2 had loose bodies, and 1 had osteochondritis dissecans). Twenty-five (15%) of the 166 patients undergoing elbow arthroscopy had mild thickening of the plica without correlating clinical symptoms, which was not considered abnormal. The study group included 12 patients, 9 men and 3 women, whose mean age was 21.6 years (range, 17-33 years). There were 7 baseball pitchers (4 professional level, 2 college level, and 1 high school level), 2 softball pitchers (both college level), and 3 golfers (2 professional level and 1 college level). Eleven of the 12 subjects were right-hand dominant. All patients were evaluated preoperatively by 1 of the senior authors (R.A.G., N.S.E., L.A.Y., F.W.J.). All 12 patients had a chief complaint of posterolateral elbow pain that involved their throwing (dominant) arm or lead arm (left arm for right-handed golfers). Only 7 (58%) of the 12 subjects also complained of associated mechanical symptoms of clicking or snapping, 3 subjects (25%) experienced swelling, and 2 subjects (17%) complained of the inability to obtain full extension of the elbow. On physical examination, tenderness to palpation in the posterolateral anconeus soft spot (83%) was the most reproducible finding, followed by pain with terminal extension (67%). A flexion-pronation test result, described by Antuna and O Driscoll, 2 when painful snapping can be reproduced by flexing a pronated elbow from extension to 90 to 110 of flexion, was present in only 3 patients (25%) and was not as helpful in making the diagnosis in this particular patient population. Six patients (50%) demonstrated discomfort with resisted wrist extension, but the pain was located posterolaterally, near the anconeus soft spot and not along the lateral epicondyle or extensor tendon origin. None of the 12 patients had undergone previous elbow surgery, and none had any other concurrent elbow problems, such as ulnar collateral ligament injury, instability, loose bodies, degenerative joint disease, lateral epicondylitis, flexor/pronator or medial epicondylitis, osteochondritis dissecans, or nerve problems. Six of the 12 patients (50%) were examined as referrals for a second opinion and had received a previous diagnosis of another condition, most commonly lateral epicondylitis. All patients underwent standard plain radiographic assessment to exclude arthritis, loose bodies, and subluxation or dislocation. They all underwent MRI evaluation of the elbow. Five of the 12 patients (42%) underwent MRI arthrograms with gadolinium-enhanced contrast, and 9 of 12 (75%) were interpreted as having abnormal, thickened synovial plica (Figure 1). Synovial folds were generally considered abnormal and hypertrophic if they measured 3 mm or greater in thickness and if they were irregular or nodular in appearance. Axial images often provided the best visualization of the plica tissue. All subjects had attempted at least 3 months of nonoperative treatment including supervised physical therapy, antiinflammatory medications, and activity modification. Eight of the 12 patients (67%) received a corticosteroid injection into the area of discomfort. The injection was placed posterolaterally into the radiocapitellar joint, through the anconeus soft spot, centered between the lateral epicondyle, olecranon, and radial head. All 8 patients experienced temporary relief of pain and discomfort with the injection. All 12 patients underwent diagnostic arthroscopy of the elbow. Ten patients were positioned in the lateral decubitus position, whereas 2 patients were positioned in the supine position, based on surgeon preference. The anterior compartment was visualized first from a proximal medial portal, and debridement of the anterior component of the plica was performed with a motorized shaver if thickened, hypertrophic tissue was encountered. The presence of synovitis and chondromalacia was noted. The lateral compartment was visualized from the posterolateral portal, and debridement of abnormal plica tissue with a motorized shaver was performed from a direct lateral portal (Figure 2). The posterior compartment was then visualized from a straight posterior portal, and care was taken to inspect the posterolateral portion of the plica and resect hypertrophic tissue, along with any localized synovitis and thickened tissue, using a posterolateral portal (Figure 3). Postoperatively, the patient s arm was placed in a sling, but active range of motion was instituted immediately. All patients had formal, supervised physical therapy for range of motion exercises and modalities. A strengthening program was begun at 3 to 4 weeks, and light throwing or a short-swinging program was started at 6 to 8 weeks. Patients were evaluated at follow-up by questionnaire and clinical examination by a single examiner (D.H.K.), based on a standardized method for assessment of elbow function adopted by the American Shoulder and Elbow Surgeons 11 and a modified elbow score (maximum, 100 points), adapted from a rating system reported by Micheli et al 13 (Table 1). Self-evaluated pain level, return to play (function), and overall satisfaction were assessed. Clinical examination included measurement of range of motion with the use of a goniometer, assessment for ligamentous stability, testing of motor strength, inspection for soft tissue swelling or effusion, and palpation for detecting any areas of tenderness. RESULTS The mean clinical follow-up was 33.8 months (range, 24-65.5 months). The mean time interval between the onset of symptoms and arthroscopic surgery was 9.25 months (range, 3-24.5 months). Arthroscopic Findings All patients demonstrated a thickened, hypertrophic lateral synovial plica. Eight patients (67%) had associated

440 Kim et al The American Journal of Sports Medicine A D B E Figure 1. Magnetic resonance image (MRI) appearance of an elbow with posterolateral hypertrophic plica. A, sagittal MR image demonstrating thickened, irregular plica (arrow). B, sagittal MR image of a normal elbow. C, coronal MR image of an elbow with hypertrophic posterolateral plica (arrow). D, coronal MR image of a normal elbow. E, axial MR image of an elbow with posterolateral, thickened, abnormal plica (arrow). Pain C synovitis and inflammation of the adjacent capsular tissue requiring additional debridement. Seven patients (58%) demonstrated chondromalacia with visible changes of the articular cartilage, most commonly involving the capitellum and posterolateral distal humerus (5 patients), followed by the radial head (2 patients). Eight patients (67%) experienced no posterolateral elbow pain (rated 0 of 10) at follow-up. Three patients had mild discomfort with sports-related activity (rated a mean of 2.3 of 10), whereas only 1 patient experienced occasional pain with moderate activities (rated 4 of 10). None of the patients was taking any pain medication for elbow symptoms. Mechanical Symptoms (Clicking, Catching, or Locking) Of the 7 patients with preoperative complaints of lateral elbow snapping, clicking, or catching, only 2 (29%) had persistent mechanical symptoms postoperatively,

Vol. 34, No. 3, 2006 Lateral Synovial Plicae in Throwing Athletes and Golfers 441 A A B B Figure 3. Arthroscopic images of the radiocapitellar joint viewed from the posterior portal. A, impingement caused by the posterolateral component of synovial plica (double arrows). B, after debridement and removal of thickened synovial tissue. Range of Motion C Figure 2. Arthroscopic images of the radiocapitellar joint viewed from the posterolateral portal. A, impingement of the joint caused by a thickened, hypertrophic plica (double arrows). B, chondromalacia of the radial head (arrow). C, motorized shaver introduced from the direct lateral portal to debride the plica tissue. but these symptoms were not painful. None of the other 5 patients developed any further mechanical symptoms after surgery. The mean postoperative range of motion was from 2 to 139 of flexion (compared with 6-136 of flexion preoperatively). Supination averaged 88 of flexion (versus 85 of flexion preoperatively), and the mean pronation was 80 of flexion (versus 80 of flexion preoperatively). There was no statistically significant difference between preoperative and postoperative elbow motion. Subjective Satisfaction All patients were satisfied with having undergone elbow arthroscopic surgery (rated 10 of 10), and all but one patient reported that they would undergo the procedure again and would also recommend the treatment to others. That patient was still satisfied with his outcome but stated that if he could choose again, he would not have undergone the arthroscopy. He sustained a separate elbow injury to the ulnar collateral ligament at a later date that ultimately required reconstructive

442 Kim et al The American Journal of Sports Medicine TABLE 1 Modified Elbow Scoring System (0-100 Points) Pain None 20 Rare 15 Occasional 10 With sport 5 Mechanical symptoms (catching or clicking) None 20 Rare 15 Occasional 10 With sport 5 Range of motion flexion contracture < 5 20 5-15 15 16-35 10 > 35 5 Activities No limit 20 Occasional limit 15 Partial activities only 10 Difficulty with activities of daily living 5 Return to sport No limitation/competitive 20 Mild limitation/recreational 15 Significant limitation 10 Unable to participate 5 Overall outcome Score Excellent 90-100 Good 80-89 Fair 60-79 Poor < 60 surgery and was not related to the elbow arthroscopy or the previously diagnosed plica syndrome. Return to Play Eleven patients (92%) were able to return to their previous level of play. The mean time to return to competitive play was 4.8 months (range, 3-9.5 months). One patient, a professional baseball pitcher who underwent later reconstructive surgery of the ulnar collateral ligament, was unable to return to the same level of play and had to retire from his sport. Modified Elbow Score The mean elbow score at follow-up was 92.5 points (range, 75-100 points). Nine patients (75%) had an excellent outcome, 2 patients (17%) had a good outcome, and 1 patient (8%) had a fair outcome. Complications There were no direct complications resulting from the surgery. As stated earlier, one patient developed subsequent medial instability that later required reconstructive surgery. DISCUSSION Throwing athletes and golfers are susceptible to a variety of elbow injuries because of the stresses and repetitive loads placed on their arms. For throwers, common conditions include medial instability with ulnar collateral ligament injury, flexor/pronator strain or tendinitis, medial epicondylitis, ulnar neuritis, valgus extension overload syndrome, loose bodies, and osteochondritis dissecans. 4,12,18,19 Golfers are also particularly prone to elbow injuries; a recent epidemiologic study in professional and amateur golfers revealed that the elbow was the most commonly injured area. 8 Among these elbow problems, a hypertrophic synovial plica causing posterolateral impingement and pain is not a commonly encountered condition. However, it has been our experience that isolated posterolateral elbow pain, often in conjunction with mechanical symptoms such as snapping or catching, does occur in these athletes and is often caused by inflammation and thickening of the elbow synovial plica. In general, synovial plicae are thought to be normal structures that represent remnants of mesenchymal tissue or embryonic septae formed during development. 16 When these structures thicken or become inflamed, they can cause pain and mechanical symptoms in the joint. Hypertrophic or thickened synovial plica of the knee is a well-recognized clinical entity 7,9,10,14,15,17 and can be readily treated with arthroscopic debridement if diagnosed appropriately. As our understanding and techniques of elbow arthroscopy have improved, hypertrophic synovial plica of the elbow has become a more recognized finding. Clarke 5 was one of the first to report the clinical success of arthroscopic excision of a fibrotic synovial elbow fold impinging between the radial head and capitellum, in a series of 3 patients with pain and mechanical symptoms initially thought to be caused by intra-articular loose bodies. Commandre et al 6 reported a single case of successful arthroscopic excision of an elbow synovial fold with associated synovitis causing pain but no mechanical symptoms. Akagi et al 1 described a patient with a thickened synovial elbow plica resulting from repetitive microtrauma, which led to pain and snapping with range of motion and was treated with open excision of the plica. More recently, Antuna and O Driscoll 2 reported on 14 patients treated arthroscopically for painful, snapping elbows caused by hypertrophic plicae. In half the patients, they could reproduce the snapping by passively flexing the pronated elbow (flexion-pronation test). All patients had localized synovitis, and all but one patient had associated chondromalacia of either the radial head or capitellum. Arthroscopic excision resulted in the improvement of pain and of snapping in 12 patients (86%). The senior author (F.W.J.) treated a professional golfer for recurrent posterolateral elbow pain and grinding. The patient had failed nonoperative management including rest, physical therapy, and corticosteroid injections. Because an MRI examination suggested thickened scar tissue along the

Vol. 34, No. 3, 2006 Lateral Synovial Plicae in Throwing Athletes and Golfers 443 radiocapitellar joint and possible chondral changes involving the capitellum and because the patient was not responding to nonoperative management, surgery was advised. Operative treatment consisted of an open arthrotomy and excision of a large, thickened plica flap. There was some notable chondromalacia of the capitellum. The patient fully recovered and was able to return to playing golf at such a high level that he played for the United States Ryder Cup team. This case stimulated the hypothesis that a hypertrophic, inflamed elbow plica may cause posterolateral elbow pain in athletes who engage in repetitive motion of their upper extremities, such as golfers and throwers. All but one patient in this study were high-level athletes, ranging from Division I college student-athletes to professional major league baseball pitchers and professional golfers. Only 2 of the 12 athletes (17%) could recall a specific traumatic event that started their symptoms. Each athlete engaged in countless repetitive movements of the elbow, especially full extension during the follow-through phase of throwing or swinging. It seems plausible that a normal elbow synovial fold could become irritated and inflamed with this type of repetitive microtrauma and could then develop thickening and hypertrophic changes. These changes could then create catching and snapping over the radiocapitellar joint, causing abrasion over the articular cartilage of the capitellum or radial head, leading to chondromalacia changes. It is important to note that none of the patients in this study had instability, intra-articular loose bodies, lateral or medial epicondylitis, osteochondritis dissecans, arthritis, or other more common conditions. These conditions were specifically excluded for the purpose of studying the results and effects of isolated arthroscopic plica excision in this patient population. Certainly, these more frequently occurring disorders should be suspected first and foremost in athletes who seek treatment for lateral elbow pain. In particular, lateral epicondylitis is probably the most common initial diagnosis. However, if the pain is localized to a more posterolateral location, often over the anconeus muscle, rather than on the lateral epicondyle or over the extensor tendon origin and if the pain is accompanied by mechanical symptoms of clicking or catching, one should consider posterolateral impingement due to a hypertrophic lateral elbow plica in the differential diagnosis. A corticosteroid and local anesthetic injection in the posterolateral elbow can also be helpful in confirming the diagnosis. In this series, all 8 patients experienced temporary relief of pain and discomfort, but when they returned to their sport, their symptoms returned. During surgery, it is important that the entire synovial fold is well visualized to perform an adequate resection of the plica. This visualization requires careful inspection of the radiocapitellar joint from the anterior compartment as well as visualization of the posterolateral aspect of the radiocapitellar joint from a posterior or posterolateral approach. In fact, a comprehensive evaluation of the lateral elbow should be performed during all routine elbow arthroscopic procedures. Often a hypertrophic lateral plica is seen when arthroscopically treating loose bodies, osteochondritis dissecans, or degenerative arthritis of the elbow; in these instances, the plica should be resected. In this study, 11 of 12 subjects (92%) reported an excellent or good outcome with a mean elbow score of 92.5 points (maximum, 100 points). We chose this elbow scoring system because part of the score included the evaluation of return to play. In our estimation, this criterion is one of the most important determinants of outcome for this particular athletic patient population. When presenting surgical options to athletes who compete at a high level or whose livelihood depends on playing their sport, they want to know when and how effectively they are able to return to play after the procedure. Although the surgical procedure in all cases involved only arthroscopic debridement and no reconstruction or open procedures, the mean time to return to competitive play was still 4.8 months. This finding may in part have been attributed to a structured postoperative therapy program, requiring the athletes to refrain from throwing or swinging for a minimum of 6 to 8 weeks, followed by a progressive throwing or swinging program, before even participating in their sport. Moreover, most of these athletes were returning to a very high level of performance to compete in their respective sports. The presence of chondromalacia did not appear to adversely affect the outcome. All 7 patients with arthroscopically visualized chondromalacia reported an excellent outcome at short-term follow-up, with a mean elbow score of 92.1 points, and the mean return to competitive play was 4.9 months. It is unclear what the long-term effects, if any, of elbow chondromalacia will be in this athletic population. Perhaps symptoms of pain and swelling may eventually develop, but more clinical studies with longer follow-up are needed to study this issue further. Mechanical symptoms of snapping or catching were present in 7 of the 12 patients (58%) preoperatively and were resolved in 5 of the 7 subjects (71%) with arthroscopic debridement. The remaining 2 patients with persistent snapping or catching did not have significant pain, and both were able to return to their previous level of play, with no limitations. We can only speculate that the persistent snapping was caused by postoperative scarring or perhaps recurrence of the plica, but we cannot confirm this supposition because neither patient had a further MRI examination or underwent repeat elbow arthroscopy. All patients had a preoperative MRI examination to help confirm the presence of a thickened synovial plica and also to rule out other abnormal conditions such as loose bodies or articular cartilage injury. These studies appeared to be useful, as 9 of the 12 patients MRI scans were interpreted as abnormal. It is important to note that experienced musculoskeletal radiologists read these MRI scans. A recent anatomical and clinical study of elbow plica suggested that synovial folds of more than 3 mm in thickness were abnormal and correlated with clinical symptoms. 3 In the current study, we determined that synovial tissue was abnormal based on 2 criteria: a thickness measuring 3 mm or greater and an irregular or nodular appearance. We also found MRI arthrography to be very helpful in making this determination, especially if the elbow did not have a significant effusion. It is important to note that the MRI examination was a helpful tool in confirming the diagnosis of a symptomatic elbow plica. However, the decision to proceed with

444 Kim et al The American Journal of Sports Medicine surgery was based on persistent clinical symptoms and on the failure to respond to nonoperative management. Limitations of this study were that it was retrospective in nature and that the study population was small. Our study consisted of 18 patients during the course of 4 years in a busy clinical practice, which underscores the relatively rare occurrence of this condition. In summary, throwing and golfing athletes can experience elbow problems because of a variety of problems. A rare but possibly underdiagnosed condition in these athletes is posterolateral elbow impingement from a hypertrophic or thickened synovial plica, causing posterolateral elbow pain, which can be associated with snapping or catching. When carefully diagnosed and when other more common conditions are excluded, treatment with elbow arthroscopy and debridement of the abnormal plica tissue, followed by focused postoperative rehabilitation, can be very successful and allows these athletes to return to their previous level of play. REFERENCES 1. Akagi M, Nakamura T. Snapping elbow caused by the synovial fold in the radiohumeral joint. J Shoulder Elbow Surg. 1998;7:427-429. 2. Antuna SA, O Driscoll SW. Snapping plicae associated with radiocapitellar chondromalacia. Arthroscopy. 2001;17:491-495. 3. Awaya H, Schweitzer ME, Feng SA, et al. Elbow synovial fold syndrome: MR imaging findings. AJR Am J Roentgenol. 2001;177:1377-1381. 4. Cain EL Jr, Dugas JR, Wolf RS, Andrews JR. Elbow injuries in throwing athletes: a current concepts review. Am J Sports Med. 2003;31:621-635. 5. Clarke RP. Symptomatic, lateral synovial fringe (plica) of the elbow joint. Arthroscopy. 1988;4:112-116. 6. Commandre FA, Taillan B, Benezis C, Follacci FM, Hammou JC. Plica synovialis (synovial fold) of the elbow: report on one case. J Sports Med Phys Fitness. 1988;28:209-210. 7. Dorchak JD, Barrack RL, Kneisl JS, Alexander AH. Arthroscopic treatment of symptomatic synovial plica of the knee: long-term followup. Am J Sports Med. 1991;19:503-507. 8. Gosheger G, Liem D, Ludwig K, Greshake O, Winkelmann W. Injuries and overuse syndromes in golf. Am J Sports Med. 2003;31:438-443. 9. Hughston JC, Whatley GS, Dodelin RA, Stone MM. The role of the suprapatellar plica in internal derangement of the knee. Am J Orthop. 1963;5:25-27. 10. Jackson RW, Marshall DJ, Fujisawa Y. The pathologic medical shelf. Orthop Clin North Am. 1982;13:307-312. 11. King GJ, Richards RR, Zuckerman JD, et al. A standardized method for assessment of elbow function. Research Committee, American Shoulder and Elbow Surgeons. J Shoulder Elbow Surg. 1999;8: 351-354. 12. Maloney MD, Mohr KJ, ElAttrache NS. Elbow injuries in the throwing athlete: difficult diagnoses and surgical complications. Clin Sports Med. 1999;18:795-809. 13. Micheli LJ, Luke AC, Mintzer CM, Waters PM. Elbow arthroscopy in the pediatric and adolescent population. Arthroscopy. 2001;17: 694-699. 14. Mital MA, Hayden J. Pain in the knee in children: the medial plica shelf syndrome. Orthop Clin North Am. 1979;10:713-722. 15. Muse GL, Grana WA, Hollingsworth S. Arthroscopic treatment of medial shelf syndrome. Arthroscopy. 1985;1:63-67. 16. Ogata S, Uhthoff HK. The development of synovial plicae in human knee joints: an embryologic study. Arthroscopy. 1990;6:315-321. 17. Richmond JC, McGinty JB. Segmental arthroscopic resection of the hypertrophic mediopatellar plica. Clin Orthop Relat Res. 1983;178: 185-189. 18. Safran MR. Elbow injuries in athletes: A review. Clin Orthop Relat Res. 1995;310:257-277. 19. Yocum LA. The diagnosis and nonoperative treatment of elbow problems in the athlete. Clin Sports Med. 1989;8:439-451.