Comparing Surgical and Nonsurgical Outcomes of Cubital Tunnel Syndrome

Background and Rationale Cubital tunnel syndrome (CuTS) is the second most common peripheral nerve compression syndrome of the upper extremity after carpal tunnel syndrome. It results from compression or traction of the ulnar nerve at the elbow, most commonly at the cubital tunnel retinaculum or the aponeurosis of the flexor carpi ulnaris. Clinical manifestations include paresthesias and numbness in the ring and small fingers, intrinsic hand weakness, and pain along the medial elbow.

Current management strategies range from conservative measures, such as activity modification and elbow bracing, to surgical intervention, including in-situ decompression and ulnar nerve transposition. For mild-to-moderate disease, the current standard of care is an initial trial of conservative management with elbow night splinting, with surgical intervention reserved for patients who do not improve or whose symptoms progress. However, the comparative effectiveness of this staged approach versus early surgical intervention has not been rigorously evaluated in a prospective, randomized trial. Additionally, objective measures of ulnar nerve structure and function have not been systematically correlated with clinical and patient-reported outcomes across treatment approaches.

Study Objective This study aims to address this gap by prospectively comparing initial conservative management with early surgical intervention for mild-to-moderate cubital tunnel syndrome. Participants will be followed for two years to evaluate clinical, functional, imaging, electrodiagnostic, and patient-reported outcomes and to assess the frequency and timing of conversion from conservative to surgical management.

Study Design This is a prospective, single-center, randomized controlled trial. Eligible participants will be randomly assigned in a 1:1 ratio to either conservative management with elbow night splinting or early surgical intervention.

Randomization will be performed using a computer-generated block randomization scheme with variable block sizes, stratified by disease severity (mild vs. moderate per Dellon classification). The allocation sequence will be concealed in sequentially numbered, opaque, sealed envelopes opened at the time of enrollment.

Patient Population Adults with mild-to-moderate cubital tunnel syndrome who meet the study eligibility criteria will be considered for enrollment. Participants must be able to provide informed consent and comply with study procedures and follow-up. Patients with severe disease, prior ulnar nerve surgery on the affected side, conditions that could substantially confound assessment of ulnar nerve function, acute traumatic conditions of the affected extremity, or other protocol-defined exclusion criteria will not be eligible.

• Cubital tunnel release (Procedure), also known as ulnar nerve decompression: This surgical intervention occurs without other prior conservative intervention.
• Conservative Arm (Procedure), also known as night splinting, activity modification, anti-inflammatory medications, physical therapy, corticosteroid injections, watchful waiting: Conservative management with the option to convert to surgical intervention if conservative measures fail

Primary outcomes

• Change in Patient-Rated Ulnar Nerve Evaluation (PRUNE) Score from baseline to 1 year [Baseline, 6 weeks, 3 months, 6 months, 1 year]: 0 indicates no symptoms or functional deficits; 100 indicates worst possible symptoms and functional deficits; "change" refers to differences between each timepoint and the baseline, as well as the differences between each consecutive timepoint

Secondary outcomes

• Change in Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) at Each Timepoint; "change" refers to differences between each timepoint and the baseline, as well as the differences between each consecutive timepoint [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: 0 indicates no disability; 100 indicates the most severe disability; "change" refers to differences between each timepoint and the baseline, as well as the differences between each consecutive timepoint
• Grip strength [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Change in grip strength measured with a Jamar dynamometer
• Pinch strength [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Change in lateral, tip, and palmar pinch strength.
• Two-point discrimination [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Change in static and moving sensory discrimination in the ulnar nerve distribution.
• Semmes-Weinstein monofilament threshold [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Change in sensory threshold in the ulnar nerve distribution.
• Ulnar nerve cross-sectional area [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Change in ultrasound-measured ulnar nerve size at the cubital tunnel.
• Ulnar nerve conduction velocity [Baseline and 1 year]: Change in sensory and motor conduction velocity across the elbow.
• Electrodiagnostic severity grade [Baseline and 1 year]: Change in overall electrodiagnostic severity classified as normal, mild, moderate, or severe.
• McGowan/Dellon grade [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Change in clinical severity classification of cubital tunnel syndrome.
• Rate of Surgical Conversion [From initiation of conservative treatment through 6 months of treatment]: Proportion of participants in the conservative arm who proceed to surgical treatment.
• Time to conversion [From initiation of conservative treatment through 6 months of treatment]: Time from initiation of conservative treatment to surgical conversion
• Patient satisfaction [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Participant-reported satisfaction with treatment outcome using a 5-point Likert scale (minimum 1; maximum 5; higher score indicates greater satisfaction)
• Global Rating of Change [Baseline, 6 weeks, 3 months, 6 months, 1 year, 2 years]: Participant-reported overall change in symptoms and function (minimum -3 indicating much worse; maximum +3 indicating much better)
• Return to work [From surgery until return to work or two years after enrollment, whichever comes first]: Time required to return to work following surgical treatment.
• Return to full activity [From surgery until return to full activity or two years after enrollment, whichever comes first]: Time required to resume full activity following surgical treatment
• Complication rate [From treatment initiation through 2 years after enrollment]: Occurrence of treatment-related complications
• Reoperation rate [From initial surgery through 2 years after enrollment]: Occurrence of revision or repeat surgical treatment
• PRUNE clinically meaningful improvement [From enrollment to 1 year after enrollment]: Change in PRUNE score corresponding to meaningful patient-reported improvement, determined using patient satisfaction and Global Rating of Change at 1 year as anchors. Patients reporting "satisfied" or "very satisfied" and/or positive change will be considered meaningfully improved, and ROC analysis will be used to identify the PRUNE change threshold that best distinguishes meaningful improvement from non-meaningful improvement.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Age 18 years or older
* Mild-to-moderate severity based on McGowan and Dellon classification:

  * Mild: Purely sensory symptoms without motor deficit or intrinsic atrophy
  * Moderate: Sensory symptoms with mild motor weakness (grip or pinch) without fixed clawing or significant intrinsic wasting
* Symptom duration of at least 6 weeks
* Willing and able to comply with follow-up schedule, study procedures, and splinting protocol if randomized to conservative management
* Able to provide written informed consent

Exclusion Criteria:

* Severe cubital tunnel syndrome by McGowan and Dellon classification (fixed intrinsic weakness, significant muscle wasting, or complete sensory loss)
* Prior ulnar nerve surgery at the elbow on the affected side
* Concomitant peripheral neuropathy (e.g., diabetic neuropathy, Charcot-Marie-Tooth disease) that may confound electrodiagnostic or clinical assessment
* Active elbow fracture, dislocation, or other acute traumatic injury to the affected extremity
* Known space-occupying lesion at the cubital tunnel (e.g., ganglion cyst, lipoma, bony spur) identified on prior imaging
* Inflammatory arthropathy affecting the elbow (e.g., rheumatoid arthritis)
* Pregnancy
* Inability to comply with follow-up visits or complete patient-reported outcome instruments
* Concurrent participation in another interventional study affecting upper extremity function

• John R Fowler, MD, Principal investigator, University of Pittsburgh Medical Center