Smartphone Habits May Be Taking a Toll on the Ulnar Nerve

For primary care physicians and orthopedic surgeons, the ubiquity of smartphones in America may represent more than a cultural shift – it may also be contributing to an increase in repetitive upper extremity conditions, including cubital tunnel syndrome (CuTS).

An estimated 98% of U.S. adults own a cell phone and 91% use a smartphone, according to Pew Research Centerdata. Americans now spend an average of more than five hours per day on their mobile devices, not including phone calls.

“Long-term technology habits may predispose some people to peripheral nerve injuries including what is now often referred to as smartphone elbow,” cautions orthopaedic surgeon Peter Evans, MD, PhD, a specialist in upper extremity and peripheral nerve surgery at Cleveland Clinic in Stuart, Florida.

Dr. Evans serves as Vice Chair of the Integrated Surgical Institute and Division Chair of Orthopaedic Surgery, Rehabilitation, and Sports Therapy for Cleveland Clinic in Florida.

A common entrapment neuropathy

Cubital tunnel syndrome is the second most common entrapment neuropathy of the upper extremity after carpal tunnel syndrome, with a reported prevalence in one U.S. metropolitan area ranging from 1.8% to 5.9%. The condition results from compression or irritation of the ulnar nerve as it traverses the posterior elbow around the medial condyle of the humerus.

CuTS most commonly develops from prolonged elbow flexion, repetitive elbow motion, leaning on the elbow, or underlying joint pathology. “When the elbow is flexed for a prolonged period, such as when speaking on the phone or sleeping with it bent at night, the ulnar nerve is placed in tension,” explains Dr. Evans.

The nerve elongates during elbow flexion, while the cubital tunnel simultaneously narrows, increasing intraneural pressure. Compression may also arise from surrounding fascial bands or external pressure from leaning on the elbow while driving, working, or using handheld devices.

Increased pressure compromises blood flow, leading to nerve ischemia, edema, and progressive enlargement of the nerve. Less commonly, symptoms may occur when the nerve repeatedly slips in and out of place during elbow movement (ulnar nerve subluxation), producing inflammation through repetitive friction.

Diagnosis relies on clinical evaluation

Diagnosis of CuTS relies primarily on patient history, physical examination, and electromyography (EMG), although EMG is often less sensitive in early-stage disease.

Patients commonly report numbness, tingling, or pain affecting the ring and small fingers as well as the medial forearm. According to Dr. Evans, dorsal ulnar hand numbness is a particularly important diagnostic clue.

“It’s important to remember that ulnar nerve symptoms may be manifested by any of three anatomical sites — compression at the wrist (Guyon’s canal), elbow, or cervical spine,” he says. “Numbness involving the back of the hand suggests compression above the wrist, which helps differentiate cubital tunnel from Guyon’s canal compression.”

Because the ulnar nerve originates in the cervical spine, proximal compression from cervical disc herniation or degenerative arthritis should also be considered in the differential diagnosis. Additional risk factors for CuTS include diabetes, obesity, and certain anatomical factors, such as bone spurs and arthritis of the elbow.

“Diabetes increases nerve vulnerability because of reduced microvasculature, while obesity may increase compression from adipose tissue surrounding the cubital tunnel,” says Dr. Evans.

Radiographs may help exclude structural abnormalities but generally have limited diagnostic utility in confirming CuTS. MRI is not routinely indicated, although ultrasound may be useful in evaluating recurrent disease. “We often use ultrasound to identify scar tissue and areas of nerve kinking in patients with recurrent symptoms after surgery,” Dr. Evans adds.

Conservative management

Primary care physicians are frequently the first clinicians to diagnose and manage cubital tunnel syndrome. Initial treatment generally includes activity modification, nighttime bracing or splinting, ergonomic interventions, icing, anti-inflammatory medications, and physical therapy.

Minimizing repetitive elbow flexion, avoiding resting the inner elbow on hard surfaces, like an armrest, and optimizing diabetes control are important preventive measures. Behavioral changes may include switching hands during phone use, using hands-free devices, and modifying workstation keyboards to avoid elbow flexion greater than 90 degrees.

Dr. Evans estimates that approximately 25% to 30% of his patients are successfully managed nonoperatively, particularly when the condition is identified early.

If compression persists, however, patients may develop progressive weakness, hand fatigue, and eventually intrinsic muscle dysfunction. Chronic severe compression can result in clawing of the ring and small fingers and inability to abduct/adduct the fingers.

Evolving surgical techniques

Operative management aims to decompress the ulnar nerve and prevent ongoing neurologic deterioration. Standard procedures include simple decompression (in situ release) and anterior transposition, in which the nerve is repositioned anterior to the medial epicondyle to reduce tension.

Dr. Evans and his colleagues at Cleveland Clinic in Florida and Ohio have also adopted a newer technique known as cubital tunnel closure.

“We release the nerve, close the cubital tunnel, and then let it sit over top of the tunnel, so that it is not a full transposition, but achieves focal decompression and relief of longitudinal tension,” explains Dr. Evans. “An advantage to a full transposition is that there is less risk of nerve damage because you don't have to dissect it over as long of a distance, and it also sits in a more natural ‘C’ path, avoiding a surgeon generated ‘S’ path that can cause kinking.”

According to Dr. Evans, approximately 50% of his procedures for CuTS are in situ releases, 30% are closure procedures, and 20% are full anterior transpositions.

“Our early experience with cubital tunnel closure suggests lower complication rates and reduced surgical morbidity allowing faster recovery, although formal outcomes analysis is still pending,” he reports.

Earlier intervention may improve outcomes

The primary objective of surgical intervention for cubital tunnel syndrome is to halt disease progression, with symptom improvement as a secondary goal. Complete symptom resolution, however, is less predictable than after carpal tunnel release, notes Dr. Evans.

Studies have demonstrated symptomatic improvement following surgery in approximately 70% of patients with CuTS, compared with success rates exceeding 90% for carpal tunnel release.

Recovery is often prolonged because the site of ulnar nerve compression at the elbow is relatively distant from the intrinsic hand muscles and overlying skin. With peripheral nerve regeneration occurring at an average rate of approximately one inch per month, extended denervation may lead to irreversible muscle atrophy before reinnervation can even occur, emphasizing the need for early diagnosis and treatment.

“Earlier intervention offers the best opportunity for full sensory and motor recovery, which is why I’m more inclined to operate earlier in cases of cubital tunnel syndrome versus carpal tunnel syndrome,” Dr. Evans says.

As smartphone use continues to increase across age groups – most children receive their first mobile device at age 11 – physicians may encounter CuTS with greater frequency. Early recognition, appropriate conservative management, and timely referral remain essential to preserving long-term nerve function and hand performance.