WWW.SPORTEX.NET

graphite, vibration also dampens out faster.

‘String vibration dampers’ are unlikely to contribute enough to prevent injury (4), although they are frequently used.

Racket mechanics ● A lighter racket may help but reducing

weight also reduces power and may cause more problems with shock or jar

● Heavier rackets recoil less and ‘twist off’ less

● Softer strings reduce ‘peak force’ of impact

● More flexible shafts soften the feel of initial impact

● Softer grip materials have the same effect, as does holding the racket less firmly.

Off-axis impacts and grip strength A wider racket head is less likely to twist if hit ‘off-axis’. Studies have shown little difference in resultant ball velocity with different grip strengths in off-axis impacts (5). It takes little grip force to prevent the handle rotating within the hand on off centre impacts so all but top level players should consider using the lightest effective grip thus helping to pre- vent elbow problems (6).

Grip size EMG studies have shown that the extensor muscle activity remains at around 37% of ‘Maximum Voluntary Contraction’ for all ranges of grip sizes (small, medium and large) (7) though recommendations seem to suggest that smaller grip sizes will increase the incidence of tennis elbow.

Muscle activity In the backhand groundstroke the exten- sor carpi radialis brevis (ECRB) has high- est activity in the acceleration and early follow through phases. These high levels maybe responsible for the development of injury (8) (Fig.1). If the extensor group is already nearly at full contraction then vibration and twisting movements are transferred directly through the muscle to the teno-periosteal junction.

Pathology The result of all these factors is ‘overuse’ and inflammation of the ECRB tendon insertion at the teno-periosteal junction (9). Other tendons can be involved such

Extensor carpi-radialis longus

Extensor carpi-radialis brevis

Extensor digitorum

Extensor carpi ulnaris

Subcutaneous olecranon bursa

Anconeus

Extensor digiti minimi

©1999 Primal Pictures Ltd

Figure 1: The extensor muscles surrounding the elbow joint

as ECRL, ECU and extensor digitorum.

Microtrauma is generated by the impact and vibration produced by ball strike (10) and by repetitive eccentric and concentric contractions. This results in microtears, fibrosis, granulation tissue deposition and mucinoid degeneration (11) collectively called angiofibroblastic hyperplasia.

Diagnosis The pain of tennis elbow is characteristi- cally on the outer aspect of the elbow and is exacerbated by wrist extension and gripping. It is relieved by rest and aggra- vated by return to play. There is tender- ness just anterior and distal to the lateral epicondyle. Although several other sites have been described, this position is by far the most common.

joint degeneration, compression neuropa- thy of the radial nerve and radial tunnel syndrome (12). In the latter, the pain is more distal in the muscle belly and proxi- mal forearm at the leading edge of supina- tor. It is also more vague, diffuse and aching in nature.

Treatment Treatment in the first 48 hours 1. Early treatment should include ‘relative rest’ of the elbow but maintenance of general fitness

2. Icing can help in the first 48 hours to reduce swelling.

3. Non-steroidal anti-inflammatory med- ication can be used in the first few days but is of little use in the more chronic lesion

4. A wrist splint in 20 degrees of wrist extension can off load the elbow espe- cially in the acute stage.

Treatment after 48 hours ● Deep transverse frictional massage is helpful (13) (Fig.3)

Figure 3: Deep transverse frictions

Figure 4: Forearm extensor muscle stretch Figure 2: Resisted extension of the wrist

Pain is experienced on active resisted extension of the wrist (Fig.2), which is sen- sitised by extension of the elbow. Resisted finger dorsiflexion is characteristically painful especially with the middle finger.

Differential diagnosis It is necessary to exclude radio-capitellar

Figure 5: Mills’ manipulation SportEX 15