Elbow Myofascial Pain

Introduction

NB: Bogduk called this Elbow Fibromuscular Impairment which is not a term in current use. A more appropriate term in use today would probably be myofascial pain.

Lateral Elbow Myofascial Pain

When elbow pain is associated with tenderness exactly over the lateral epicondyle, the diagnosis – lateral epicondylitis may be entertained (see Appendix EP7). However, in some, if not many instances, tenderness is found not over the epicondyle but over the common extensor origin distal to the lateral epicondyle. The diagnosis of this combination of features is fraught with difficulties.

In some circles, the rubric – lateral epicondylitis, is applied even though this makes no sense. The condition does not involve the epicondyle; nor is there any evidence that it is inflammatory in nature.

A possible rubric is “lateral elbow pain”. This term is correct anatomically but lacks precision or definition. It nonetheless could apply if the physician wishes to be no more discriminatory. However, an examination of the anatomy of this region offers an alternative rubric.

Distal to the lateral epicondyle lie the radiohumeral joint, covered by is capsule and the annular ligament, in turn covered by the fibromuscular common extensor apparatus. Although classically a lateral collateral ligament is described, recent anatomical studies have shown that this structure is artificial. Close dissection reveals that no independent radial collateral ligament exists. Instead, the radiohumeral joint is covered by a complex of fibrous tissue derived from the fascia of the extensor muscles 1. What has been represented as the radial collateral ligament is simply the confluence of this fascia over the lateral elbow.

Tenderness over the lateral elbow, therefore, could be ascribed to a painful lesion in any of the structure in this region – the joint, its capsule, or the overlying fibromuscular tissue. Clinical examination does not have the resolution to determine which in particular of these structures is the source of pain and tenderness.

The presence of focal tenderness strongly implies that one or other of the structures is in some way impaired. An appropriate rubric is lateral fibromuscular impairment of the elbow. This term recognises that there is an impairment that causes pain, but does not presuppose a particular lesion, and does not pretend to be able to discriminate between various possibilities.

Of the possibilities pathologically are tears or sprains of the extensor muscles near their origin, tears of the capsule, synovitis, meniscoid extrapment, and radiohumeral arthropathy.

There have been no formal studies of the pathology of extensor tears or sprains. This is a hypothetical entity based on the general principles of myotendinous tears. Such tears would be consistent with the risk factors known to apply to lateral epicondylitis (see Appendix EP7).

Tears of the capsule are also hypothetical. Presumably they could arise as a result of varus injuries, but without high-resolution imaging they could not be distinguished from tears of the overlying fibromuscular apparatus. Moreover, the distinction would not lead to any different management.

Synovitis is a disorder that, in principle, can affect any synovial joint. The radiohumeral joint is no exception. Theoretically, radiohumeral arthritis could start as focal synovitis over the lateral elbow, but if the joint is destined to become inflamed, inflammation will in due course be more clearly manifest, in the form of an effusion or wider tenderness across the entire elbow. Until that occurs there is little point in sustaining a diagnosis of radiohumeral synovitis.

Meniscoid extrapment is a condition that has lapsed from contemporary attention. It was, however, described in various forms in the older literature 2-6. The radiohumeral joint contains a fibrous meniscoid, usually located around the posterior or posterolateral perimeter of the joint. The meniscoid is attached at its base to the joint capsule, and projects into the joint cavity. Some authors have identified the meniscoid as a synovial fringe 2,3,4, a mucosal flap 5, or a displaced, frayed edge of a coronary ligament akin to a semilunar cartilage 6; but the structure is more substantive than a synovial fold. It is. It is a normal feature of the joint, and not a pathological structure. Since it normally lies inside the joint, the meniscoid cannot be construed as getting trapped, or pinched, inside the joint, as some authors have maintained 2-5. However, it is conceivable that the meniscoid can be extrapped. If traction is applied to the capsule by the overlying muscles, and if the joint is also distracted distally, it is conceivable that the meniscoid could be pulled out of its normal, intra-articular location. If the joint is released without the meniscoid returning to its normal location, the meniscoid could become trapped outside the joint space, under the capsule, where it would act like a loose body. Tension on the extensor muscles, and pressure over the meniscoid would be a source of pain if nerve fibres within the meniscoid or the capsule were stimulated. Such a lesion would satisfy the features of lateral fibromuscular impairment of the elbow. By the same token, it could be imagined that tension on the caspule, by the extensors, could irritate or tear the base of the meniscoid if its apex remained caught inside a compressed radiohumeral joint. However, apart from literature noting the presence of such structures in some patients with so-called “tennis elbow”, there have been no studies that validate the theory, or show how the condition might be diagnosed. The only circumstantial evidence lies in those reports that claim relief of lateral elbow pain upon excising the meniscoid 3,4.

Like early synovitis, early radiohumeral arthropathy could, theoretically be manifest as focal tenderness over the joint. Early arthropathy, however, is unlikely to be manifest on medical imaging. If arthropathy is, indeed, the diagnosis, it will become apparent as the condition progresses, with more widespread tenderness or pain upon movements other than those that stress the common extensors.

Although this spectrum of possible pathologies can be invoked to explain lateral fibromuscular impairment, there are no means, at present, by which one can be discriminated from the other. One putative means is highly selective infiltration of local anaesthetic.

If it could be shown that a tiny amount of local anaesthetic delivered selectively to the extensor tendons relieved the patient’s pain, a diagnosis of muscle tear could be entertained. Such tears may be apparent on ultrasound 7. However, the expense of ultrasound in this context is not justified for it would not alter the intended management.

If a subcapsular infiltration of local anaesthetic relieved the patient’s pain, the source could be ascribed to the joint, and not the overlying muscles. However, other than providing a means of palliating the symptoms, as corticosteroids do for lateral epicondylitis, this intervention offers no indication for management.

In the absence of a specific diagnosis for lateral fibromuscular impairment of the elbow, specific treatments are either not available or are unproven.

According to general principles, fibromuscular tears should heal within a matter of days, with rest alone. The critical intervention would be to avoid and circumvent those movements that putatively have been, or are, responsible for the tears, particular if these are occupational in nature.

Synovitis or arthropathy will either resolve spontaneously or progress.

Meniscoid extrapment is the single condition for which specific intervention might be entertained. Manipulation of the radiohumeral joint, in the form of distraction with varus bending and flexion, is a manoeuvre that theoretically would encourage a displaced meniscoid to re-enter the joint cavity. But no studies have validated this option for lateral elbow pain.

Medial Elbow Myofascial Pain

Similar considerations apply to tenderness over the medial aspect of the elbow. In this region the elbow joint is covered by the ulnar collateral ligament and the common flexor muscles. In principle either the ligament, the tendons, or both could be sprained by valgus injuries, such as those incurred by throwing and swing movements of the forearm. Clinically, sprain of the ligament or the tendons cannot be distinguished; nor is there any point doing so, for the management would be the same.

In principle, that the source of pain lies in the tendons or the ligament could be established by selectively infiltrating either with a tiny amount of local anaesthetic, but this intervention is superfluous. In the absence of any alternative diagnosis, tenderness alone is enough to be diagnostic of fibromuscular impairment of the medial elbow.

The management of medial fibromuscular impairment is based on the principles that with rest and avoiding or circumventing the precipitating movements, the tear should heal without further, specific intervention.

References

1. Van Mameren H. Drukker J. A functional anatomical basis of injuries to the ligamentum and other soft tissues around the elbow joint: tranmission of tensile and compressive loads. Int J Sports Med 1984; 5:88-92.

2. Trethowan WH. Tennis elbow. BMJ 1929; 2:1218. 3. Bell Allen JC. Traumatic radio-humeral synovitis. Med J Aust 1947; 1:48-51. 4. Bell Allen JC. Epicondylitis: traumatic radio-humeral synovitis. Med J Aust 1944; 1:273-274. 5. Moore M. Radiohumeral synovitis. Arch Surg 1952; 64:501-505. 6. Mills GP. Treatment of tennis elbow. BMJ 1937; 2:212-213. 7. Maffulli N, Regine R, Carrillo F, Capasso G, Minelli S. Tennis elbow: an ultrasonographic study in tennis players. Br J Sports Med 1990; 24:151-155.