Medial epicondylopathy—microtrauma and pathologic overuse as a cause of degeneration of the flexor tendons

Medial epicondylitis is a common orthopedic condition that typically results from overuse or previous microtrauma of the flexor-pronator mass. Repetitive eccentric loading of the muscles leads to subsequent degeneration of the flexor tendons. Patients present with a painful elbow. In the case of concomitant elbow pathologies, including ulnar neuritis and ulnar collateral ligament injury, there should be a detailed examination. Generally, the diagnosis is based on the clinical examination. T2-weighted magnetic resonance imaging can be useful for chronic courses, over 6 months. Nonsurgical management is the mainstay of treatment. Hence, surgical treatment may be indicated for patients with persistent symptoms after conservative treatment. In the case of a surgical treatment, arthroscopy can be useful to capture concomitant elbow pathologies.


Medial epicondylopathymicrotrauma and pathologic overuse as a cause of degeneration of the flexor tendons
Background Epicondylopathy humeri ulnaris (EHU, "Golfer's elbow") is a common clinical condition in everyday clinical practice, which often severely restricts the quality of life and the everyday professional life of patients [31]. The term "epicondylitis" has been increasingly abandoned in recent times because inflammation cannot be regarded as the cause. Rather, studies have shown that microtrauma and overload lead to degenerative changes at the origin of the flexor tendons ("common flexor origin, " CFO; [4,7,30]). As a result, the tendon is restructured, which often leads to tendon failure and to instability of the elbow joint as a final consequence [15,19]. Hence, the term "epicondylitis" is more commonly used in clinical practice. The affected tendons are the pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, and the flexor carpi ulnaris muscle (. Fig. 1).
The term "golfers' elbow" is frequently used because hitting the ball increases the valgus stress on the medial condyle [16]. An incidence of 1-3% has been described in epidemiological studies, with an occurrence more often on the lateral or radial side [18,24]. The relevance of epicondylitis results from an ofteninconsistent therapy concept.
Being overweight, of moderate age (especially 40-60 years), nicotine abuse, increased effort, and repetitive/stereotyped movements of the corresponding muscle groups for at least 2 h a day are predictors for the occurrence of epicondylitis [4,7,21]. It is not uncommon for patientspecific factors such as accompanying neck pain, depressive episodes, symptom duration over 3 months, or specific physical occupational and, for example, onesided manual activities to correlate with a poorer prognosis for the patient [7,18]. The often-inconsistent therapy concepts are commonly based on the lack of uniform classification of the EHU. The distinction between an acute and a chronic form is certainly to be considered sen- sible. According to the duration of the symptoms, the EHU can be divided into an acute (<6 months) and a chronic form (>6 months).

Diagnosis
In the anamnesis the patients commonly report pain in the area of the medial epicondyle, which usually radiates into the forearm. Trauma has often preceded this, which can be understood as a trigger. Patients describe increased and stereotypical, repetitive movements in leisure time  and at work. In the course of the medical history, previous injuries and previous treatments should be queried. Previous trauma can often be seen as the trigger.

Clinical examination
The clinical examination usually focuses on a typical pain pattern. The range of motion of the affected elbow joint should be documented according to the neutral-zero method in relation to the opposite side. Often, however, the range of motion can be assessed as unrestricted. In addition to provoking pain during final movements, local pressure, stretching, and tension pain above the origin of the flexors are to be rated as typical. Various tests are available for assessment, for example, the Reversed Cozen Test. Weakness of the arm is often described in the context of chronic epicondylitis. Therefore, the detection of peripheral blood circulation, motor skills, and sensitivity are of great importance. Accompanying symptoms of the ulnar nerve are not uncommon (. Fig. 2). A positive Tinel sign can indicate compression of the ulnar nerve. If there is a clinical indication of an accompanying neurogenic pathology, a neurophysiological examination including electroneurography/ electromyography should be sought. Also, the stability of the elbow joint should be checked [28]. In particular, overhead athletes must be examined for valgus instability by applying valgus stress to the elbow in 30°of flexion, with the forearm pronated and the wrist flexed or by use of stress tests (e.g., the milking test; [3]). Possible differential diagnoses should be excluded. Therefore, an examination of the adjacent joints and the cervical spine is strongly recommended.

Imaging diagnostics
As part of the initial presentation, conventional radiological diagnosis of the elbow joint should be aimed for. In addition to free joint bodies or joint mismatches, visible arthritic changes and calcifications can be assessed.
Sonography has established itself for the assessment of tendinopathy. In addition to low-echo changes, hypervascularization in the tendon insertion of the flexor group may also be visible. Moreover, the evaluation of changes of the ulnar nerve could be possible. Park et al. showed that ultrasonography performed by a radiologist had sensitivity, specificity, and positive and negative predictive values of >90% for the diagnosis of medial epicondylitis [20]. A dynamic examination may improve sensitivity and specificity [14]. Hence, the diagnostic accuracy depends greatly on the operator.
Thus, magnetic resonance imaging (MRI) diagnostics should be used as the standard imaging tool. Especially in chronic epicondylitis, it should be the diagnostic tool of choice. To assess accompanying or even consecutive instability, MRI should be performed in supination and extension (. Fig. 3; [30]). On T2-weighted sequences, intermediate-to-high signal intensity at the common origin of the flexor tendons is typically indicative of medial epicondylitis [12]. Hence, in 50% of asymptomatic patients, edema of the CFO could be detected. Thus, it may be that CFO changes on the MRI do not correlate with the clinical symptoms of the patient [22].

Therapy
Various nonsurgical and surgical treatment options are available to manage medial epicondylitis. The initial focus of acute supportive care is to relieve the pain, rehabilitate the pathologic tendon, and prevent recurrence.

Conservative therapy
Initially, conservative therapy is the treatment of choice as complete remission can be observed in approximately 90% of cases within the first 12 months [4]. Patients should be informed about the high probability of a complete remission of the symptoms. However, structural damage of the tendon should be excluded.
In addition to the modification of repetitive stress, the spectrum of conservative therapy consists in physiotherapeutic exercise treatment, manual therapy, as well as massage therapy and anti-inflammatory oral and topical therapy. Injections with cortisone, plateletrich plasma (PRP), or botulinum toxin are the subject of ongoing discussion. Especially at the beginning of treatment, stress adjustment should be the focus of therapy. Therefore, the professional and social history of the patient is essential to be able to adjust the repetitive overload. In particular, athletes with concomitant lateral ulnar collateral ligament (LUCL) injury should avoid valgus stress during the first week of the treatment. Acute pain and swelling can be treated with ice and nonsteroidal anti-inflammatory drugs [4,11]. In the area of physiotherapeutic exercise treatment, manual therapy and friction treatment can support training therapy, but should not be understood as the only treatment [8][9][10]. In baseball pitchers with medial epicondylitis, pain relief by using the forearm kinesiology taping technique was demonstrated [5].
Injections of cortisone should be used cautiously. Although a corticosteroid injection is able to relieve medial elbow pain in the short term, multiple injections of cortisone are no longer recommended. Cortisone could induce changes of the tendon and produce necrosis of the fatty tissue [6]. In spite of the reliable clinical outcome in the short term, the midand long-term effects are debated [17]. Stahl and Kaufmann reported an acute improvement over the first 6 weeks, but no difference after 3 months [25]. Lee at al. found acute improvement in pain scores over the first 2 weeks followed by a plateau [14]. Hence, repetitive injections can also lead to a lesion of the flexors with consecutive, secondary instability. Moreover, injections should be performed carefully due to the close relationship to the ulnar nerve [25,26]. In the end, there is insufficient scientific evidence regarding the results after use and application/injection. Also, injections with botulinum toxin have shown a reliable short-term effect [6]. Injections of PRP injection are more common for lateral epicondylitis. According to the study by Suresh et al., a combined needle stimulation and injection of PRP resulted in decreased scores on the visual analog scale. Most of the patients (20 out of 26) had two autologous blood (2 ml) injections combined with 2 ml of bupivacaine [27]. Based on the literature findings, an influence of the duration of symptoms on the effect of the injection could not be evaluated. Therefore, for an early injection, there are no data in the litera-

Medial epicondylopathy-microtrauma and pathologic overuse as a cause of degeneration of the flexor tendons Abstract
Background. Medial epicondylitis is a common orthopedic condition that typically results from overuse or previous microtrauma of the flexor-pronator mass. Repetitive eccentric loading of the muscles leads to subsequent degeneration of the flexor tendons. Diagnosis. Patients present with a painful elbow. In the case of concomitant elbow pathologies, including ulnar neuritis and ulnar collateral ligament injury, there should be a detailed examination. Generally, the diagnosis is based on the clinical examination. T2-weighted magnetic resonance imaging can be useful for chronic courses, over 6 months. Treatment. Nonsurgical management is the mainstay of treatment. Hence, surgical treatment may be indicated for patients with persistent symptoms after conservative treatment. In the case of a surgical treatment, arthroscopy can be useful to capture concomitant elbow pathologies. Therapie. Aufgrund der hohen Rate an spontane Remissionen innerhalb der ersten 12 Monate ist die primäre konservative Therapie der Goldstandard. Die konservative Therapie ist als ein multimodales Therapiekonzept zu betrachten. Die operative Therapie sollte streng indiziert sein und nur chronischen Verläufen mit Beschwerdepersistenz nach Ausschöpfung aller konservativen Maßnahmen vorbehalten sein. Im Rahmen einer operativen Therapie kann eine diagnostische Arthroskopie hilfreich sein, um intraartikuläre Begleitpathologie oder eine sekundäre Instabilität zu erfassen.

Schlüsselwörter
Mediale Epikondylitis · Mikrotrauma · Flexorenursprung · Läsion des ulnaren Kollateralbands · Ulnarneuritis ture to date to support this recommendation. Electrical and ultrasound therapy and extracorporeal shock wave treatment (ESWT) may promote pain relief. Lee at al. reported worse clinical pain scores at 1 and 2 weeks with EWTS, but better patient satisfaction at 8 weeks [14]. A good or excellent clinical outcome at 1-yearfollow-up was observed by Krischek et al. [13,23]. An overview of a possible conservative therapy algorithm is presented in . Fig. 4.

Surgical therapy
The indicationforsurgical therapyshould be strictly limited. Only after exhausting all conservative measures should Obere Extremität 4 · 2020 291 Übersicht (1) Exclusion of a structural tendon damage and (2) exclusion of a chronic process (see surgical therapy)

Medical history/clinical examinaƟon and imaging diagnosƟcs (presented in the text)
• Stress adjustmentin hobbies and work place (avoidance of repeƟƟve wrist flexion, forearm pronaƟon, and valgus stress) • AnƟ -inflammatory oral therapy (non-steroidal anƟ-inflammatory drugs (NSAIDs)) and topical therapy (cryotherapy) 4 x daily 10 -15min.  After incision of the flexor tendons, a type of calcine tissue becomes visible patients with persistent symptoms over 9-12 months and structurally-morphologically proven damage be considered. The good clinical results after operative therapy should be discussed in terms of spontaneous complaint remission and possible intraoperative complications. Therefore, detailed patient information is essential. Based on the available literature, no uniform superiority of one of the methods could be demonstrated, so that compared with lateral epicondylitis no uniform recommendation is possible. Moreover, there are only a few studies dealing with the postoperative followup after a surgical therapy for medial epicondylitis. Vangsness et al. observed in 88% of patients a reliable clinical outcome after 6 years. Frequently used open procedures are the so-called classic Hohmann operation, as a crescentshaped release of the flexors, including the degenerative tissue from the medial epicondyle [29]. The "Wilhelm operation" with denervation of nerve structures at the medial epicondyle, and the "operation after Nirschl" [18], in which the flexor group is incised lengthways and the degenerative tissue is subjected to debridement-without detachment of the origins-are further surgical treatment options (. Fig. 5).
In addition to the open procedures, percutaneous or arthroscopic surgical techniques according to the lateral epicondylitis are the subject of debate [1,2]. However, arthroscopy in medial epicondylitis is currently of only minor importance due to the close relationship to the ulnar nerve. For lateral epicondylitis, several recent studies have recommended arthroscopy for assessing intra-articular pathologies; for the me-dial side there are not data so far that support this recommendation. Nonetheless, arthroscopy for assessing hidden instability or intra-articular pathologies should not be underestimated. For this reason, prior diagnostic arthroscopy, especially in the case of chronic illnesses, is often recommended to ensure that the treatment is appropriate for the cause. Taking the clinical symptoms and the MRI findings into account, a holistic operative therapy concept can be considered one or two times. It is not uncommon for diagnostic arthroscopy to show a relevant instability, which can then be treated with additive stabilization (reinsertion/gathering/internal bracing of the LCL/MCL complex or lateral ulnar collateral ligament/medial collateral ligament [LUCL/MCL] plastic). However, most of the patients are in their 5th-6th decade of life and a ligament reconstruction is not indicated for every mild instability. Thus, the indication for surgical therapy should be strictly limited.

Practical conclusion
4 Medial epicondylitis is a result of degenerative changes in the origin of the flexor based on microtrauma and pathological overload. 4 Any accompanying instability should be checked during the clinical examination. 4 In approximately 90% of cases, there is a spontaneous remission of symptoms within the first 12 months. 4 The primary therapy of choice is conservative. The available therapy options should be understood as a multimodal therapy concept. 4 Stress adjustment is a critical factor in primary treatment. 4 The indication for operative therapy should be strictly limited and only reserved for chronic courses with complaint persistence despite exhausting all conservative measures. 4 Above all, diagnostic arthroscopy has a role in a causal operative therapy concept.