Clinical History
A 42-year-old right-handed male competitive club tennis player presented with a six-month history of progressively worsening pain affecting his dominant right forearm.
He competed regularly in both singles and doubles and had previously played at a high amateur level. Over the preceding season, his tennis load had increased substantially due to participation in club league matches and tournaments.
Initially, he experienced a dull aching pain over the lateral aspect of the proximal forearm, localised to the extensor compartment approximately 3–5 cm distal to the lateral epicondyle. As symptoms progressed, the pain developed into a burning sensation that became increasingly severe during prolonged rallies, particularly when hitting topspin forehands.
He reported that after several forehands the discomfort would gradually crescendo, making it increasingly difficult to grip the racket. On several occasions he had been forced to retire from matches because he could no longer comfortably hold the racket. His serve also became less effective once symptoms developed.
Massage over the lateral forearm temporarily relieved his symptoms. He denied any significant weakness of finger or wrist extension but occasionally experienced a vague “buzzing” sensation radiating down the dorsal aspect of the forearm into the dorsum of the hand.
More recently, symptoms had begun to persist after tennis sessions, with aching discomfort occurring during the evening and occasionally waking him at night.
There was no previous history of lateral elbow pain or upper limb injury.
Past Medical History
No previous elbow or upper limb pathology.
Otherwise fit and well.
Drug History
No regular medications.
Exercise History
Competitive club tennis player competing in singles and doubles.
Comprehensive strength and conditioning programme incorporating upper and lower body resistance training.
Regular forearm strengthening exercises.
No recent reduction in strength training.
Equipment history revealed several important recent changes:
Yonex Ezone racket.
Full polyester string set-up.
String tension had recently been increased from approximately 52 lbs to 58–59 lbs to improve ball control.
Increased competitive match load over the preceding six months.
He worked as a university lecturer and spent prolonged periods using a computer but performed no repetitive manual work.
Examination
Inspection demonstrated no swelling or muscle wasting.
There was maximal tenderness approximately 4 cm distal to the lateral epicondyle over the radial tunnel rather than directly over the common extensor tendon origin.
Elbow range of motion was full.
Pain was reproduced with:
- Resisted forearm supination.
- Resisted middle finger extension (Maudsley’s test).
- Sustained gripping.
- Resisted wrist extension produced only minimal discomfort directly over the lateral epicondyle.
- Grip strength was preserved.
- Motor examination demonstrated normal strength of wrist extension and finger extension with no evidence of posterior interosseous nerve palsy.
- Sensation was normal, although prolonged provocative testing occasionally reproduced paraesthesia over the dorsal radial hand.
- Cervical spine examination was unremarkable.
Initial Investigations
Plain radiographs of the elbow were normal.
Nerve conduction studies demonstrated no abnormalities.
This is a common finding in radial tunnel syndrome, as compression is often dynamic and predominantly painful without significant axonal injury. Electrodiagnostic studies are generally more useful when posterior interosseous nerve syndrome with motor weakness is suspected.
Differential Diagnosis and Clinical Reasoning
Lateral Epicondylitis
Lateral epicondylitis remains the most common cause of lateral elbow pain in tennis players.
However, this patient’s maximal tenderness was located distal to the lateral epicondyle within the radial tunnel rather than directly over the common extensor origin. Furthermore, his symptoms consisted predominantly of burning forearm pain with intermittent paraesthesia rather than isolated tendinopathic pain.
Posterior Interosseous Nerve Syndrome
Posterior interosseous nerve syndrome represents a motor neuropathy resulting from compression of the posterior interosseous nerve.
Patients typically develop weakness of finger and thumb extension with minimal pain.
Although anatomical variation exists around the division of the radial nerve, this patient demonstrated preserved motor strength without extensor weakness, making isolated posterior interosseous nerve syndrome unlikely.
Radiocapitellar Joint Pathology
Articular pathology including synovitis, cartilage injury or repetitive radial head stress may produce lateral elbow pain.
The absence of joint line tenderness, mechanical symptoms and normal imaging reduced the likelihood of intra-articular pathology.
Extensor Muscle or Tendon Injury
Overload of the extensor digitorum or extensor carpi ulnaris musculature may occur in tennis players, particularly in those gripping the racket excessively tightly.
While this remained a consideration, the burning quality of pain, neural symptoms and examination findings favoured neural compression.
Red Flag Diagnoses
The development of persistent night pain warranted consideration of less common but important pathology including:
- Osteoid osteoma.
- Primary bone tumours.
- Metastatic disease.
- Occult infection.
Appropriate imaging excluded these diagnoses.
Further Imaging
Dynamic musculoskeletal ultrasound demonstrated focal irritation of the posterior interosseous nerve as it passed beneath the Arcade of Frohse, with reduced nerve excursion during forearm rotation.
The Arcade of Frohse represents the fibrous proximal edge of the superficial head of the supinator and is the commonest site of radial nerve compression.
The anatomy around the radial nerve bifurcation is highly variable, explaining why some patients present with predominantly pain while others develop motor deficits.
MRI demonstrated no evidence of common extensor tendon tear, muscle injury or osseous pathology.
Diagnosis
Radial Tunnel Syndrome secondary to dynamic compression of the posterior interosseous branch of the radial nerve at the Arcade of Frohse.
Management
Management focused on reducing mechanical stress on the radial nerve while correcting contributing biomechanical factors.
Equipment Modification
Equipment assessment identified excessive grip force during forehand strokes.
This appeared to have developed following an increase in polyester string tension, resulting in greater impact forces being transmitted through the forearm.
The following modifications were made:
Grip size increased from size 3 to size 4.
Polyester string tension reduced from 58–59 lbs to approximately 54 lbs.
Coaching advice to reduce excessive grip pressure during stroke production.
Rehabilitation
Physiotherapy included:
- Radial nerve mobilisation (nerve glides).
- Progressive forearm loading.
- Soft tissue treatment to the supinator and extensor compartment.
- Load modification.
- Gradual return to tennis.
Medical Management
As symptoms progressed beyond sporting activity and began occurring at night, neuropathic pain management was introduced.
Nortriptyline 10 mg nocte significantly improved resting symptoms and reduced nocturnal pain.
Ultrasound-Guided Hydrodissection
Persistent symptoms despite conservative treatment prompted ultrasound-guided radial nerve hydrodissection.
The posterior interosseous nerve was identified at the Arcade of Frohse.
Hydrodissection was performed using:
Dexamethasone 3.3 mg.
1–2 mL of 0.25% Marcaine.
Approximately 5 mL normal saline.
The injectate was used to separate the nerve from surrounding fibrous tissue, reducing mechanical irritation and improving nerve mobility.
Outcome Of Treatment
Symptoms improved progressively following hydrodissection, equipment modification and rehabilitation.
Night pain resolved completely.
The patient gradually returned to unrestricted singles and doubles tennis without recurrence of symptoms.
At follow-up he had resumed full competitive play with no functional limitations.
Discussion and Key Clinical Learning Points
Radial tunnel syndrome is an uncommon but important cause of lateral forearm pain in racket sport athletes and is frequently misdiagnosed as lateral epicondylitis.
Careful localisation of tenderness is essential.
Pain located 3–5 cm distal to the lateral epicondyle, particularly when associated with burning discomfort or intermittent paraesthesia, should prompt consideration of radial nerve entrapment.
The distinction between radial tunnel syndrome and posterior interosseous nerve syndrome is clinically important.
Radial tunnel syndrome is predominantly a pain syndrome, whereas posterior interosseous nerve syndrome presents with motor weakness affecting finger and thumb extension.
Electrodiagnostic studies such as nerve conduction studies are frequently normal in radial tunnel syndrome and should not exclude the diagnosis when the clinical picture is convincing.
In tennis players, equipment factors should not be overlooked.
Increasing polyester string tension and excessive grip pressure substantially increase loading through the wrist extensors and supinator, potentially contributing to radial nerve irritation.
Dynamic ultrasound can provide useful assessment of nerve mobility and may identify focal compression at the Arcade of Frohse and dynamic movement.
Ultrasound-guided hydrodissection of the radial nerve is a valuable treatment option for patients who fail to respond to rehabilitation and equipment modification.
Key Clinical Learning Points
Radial tunnel syndrome should be considered in athletes presenting with burning lateral forearm pain rather than isolated lateral elbow pain.
Maximal tenderness is typically located 3–5 cm distal to the lateral epicondyle.
Distinguish radial tunnel syndrome from posterior interosseous nerve syndrome by assessing for motor weakness.
Normal nerve conduction studies do not exclude radial tunnel syndrome.
Tennis equipment, particularly grip size, polyester strings and string tension, may significantly influence forearm loading.
Ultrasound-guided hydrodissection is an effective treatment option in carefully selected patients who fail conservative management.
Take Home Message
➡️ Not all lateral elbow pain in tennis players represents lateral epicondylitis.
➡️ Careful examination and localisation of tenderness can distinguish radial tunnel syndrome from common extensor tendinopathy.
➡️ Always assess equipment, biomechanics and training load alongside the clinical examination.
➡️ Early recognition and appropriate treatment can allow a successful return to competitive sport while avoiding prolonged symptoms.
