Electrophysiologic Changes After Extended 360° Capsular Release

Electrophysiological Evidence of Neural Function Improvement After Extended Arthroscopic Circumferential Capsular Release for Adhesive Capsulitis

Frozen shoulder (adhesive capsulitis) is a condition characterized by shoulder pain and restricted range of motion, significantly impairing daily living activities. In cases that do not respond to conservative treatment, arthroscopic capsular release is an effective surgical treatment option. The 360° capsular release technique, performed by some surgeons, involves release of the inferior capsule and therefore carries a potential risk of nerve injury due to the anatomical proximity of neurovascular structures such as the axillary nerve. In addition, surgical manipulations performed around the coracoid process may exert mechanical or compressive effects on the musculocutaneous nerve and its sensory continuation, the lateral antebrachial cutaneous nerve, due to their close relationship with the lateral cord of the brachial plexus.

The aim of this prospective, single-center observational clinical study is to objectively evaluate the morphological and functional effects of inferior capsular release and coracoid region dissection performed during arthroscopic 360° capsular release surgery on the axillary and musculocutaneous nerves, using electromyography (EMG) and nerve conduction studies (NCS) in patients with frozen shoulder.

Patients aged 21-70 years with a diagnosis of frozen shoulder who have not responded to conservative treatments and are scheduled for arthroscopic capsular release will be included in the study. EMG and NCS assessments will be performed at the preoperative baseline, and at 12 weeks postoperatively. For the axillary nerve, the deltoid and teres minor muscles will be evaluated; for the musculocutaneous nerve, the biceps brachii and brachialis muscles will be assessed. Additionally, sensory conduction of the lateral antebrachial cutaneous nerve will be examined. Along with electrophysiological findings, shoulder range of motion (ROM), pain (VAS), muscle strength (MRC), and functional scores will also be recorded.

This study is expected to provide objective evidence regarding the effects of arthroscopic capsular release surgery on peripheral nerve function, thereby contributing new data on the safety of the surgical technique and enriching the currently limited literature on electromyographic evaluation in frozen shoulder surgery.

Frozen shoulder (adhesive capsulitis) is a disabling condition characterized by shoulder pain and significant limitation of active and passive range of motion. When conservative treatments such as physical therapy, medications, and intra-articular injections fail, arthroscopic capsular release is commonly performed to restore shoulder mobility.

Arthroscopic 360° capsular release involves circumferential release of the shoulder capsule, including the inferior capsule. Due to the close anatomical relationship of the inferior capsule with the axillary nerve and the proximity of the coracoid region to the lateral cord of the brachial plexus, surgical manipulation in these regions may theoretically affect the axillary and musculocutaneous nerves. While neurological complications after shoulder arthroscopy are considered rare, the electrophysiological effects of capsular release procedures on peripheral nerve function have not been systematically evaluated in prospective studies.

This prospective single-center observational clinical study aims to evaluate the morphological and functional effects of inferior capsular release and peri-coracoid dissection on the axillary and musculocutaneous nerves in patients undergoing arthroscopic 360° capsular release for adhesive capsulitis.

Patients aged 21-70 years with frozen shoulder who do not respond to conservative treatments and are scheduled for arthroscopic capsular release will be included. Electromyography (EMG) and nerve conduction studies (NCS) will be performed at baseline before surgery and repeated during postoperative follow-up.

For the axillary nerve, the deltoid and teres minor muscles will be evaluated using needle EMG. For the musculocutaneous nerve, the biceps brachii and brachialis muscles will be examined. In addition, sensory conduction studies of the lateral antebrachial cutaneous nerve will be performed.

Along with electrophysiological parameters such as motor unit potentials, recruitment patterns, distal latency, conduction velocity, and compound muscle action potential amplitudes, clinical outcomes including shoulder range of motion, pain scores, muscle strength, and functional shoulder scores will also be recorded.

The primary objective of the study is to compare preoperative and postoperative electrophysiological parameters of the axillary and musculocutaneous nerves. Secondary analyses will evaluate the relationship between electrophysiological changes and clinical outcomes such as improvement in range of motion, reduction in pain, and recovery of muscle strength.

This study aims to provide objective electrophysiological data regarding the effects of arthroscopic capsular release on peripheral nerve function and contribute to the limited literature on neurophysiological outcomes following shoulder arthroscopy. Primary Outcome Measure

Change in electrophysiological parameters of axillary and musculocutaneous nerves

Electrophysiological evaluation using electromyography (EMG) and nerve conduction studies (NCS) will be performed preoperatively and at postoperative follow-up to assess changes in nerve conduction velocity, distal latency, CMAP amplitude, and motor unit potential characteristics.

Time Frame: Preoperative baseline and postoperative follow-up. Secondary Outcome Measures

Change in shoulder range of motion (ROM) Measured using standard goniometric evaluation before and after surgery.

Pain level (VAS score) Pain intensity will be evaluated using the Visual Analog Scale.

Muscle strength (MRC scale) Motor strength of the affected upper extremity will be evaluated.

Functional shoulder scores Functional outcome will be assessed using validated shoulder scoring systems such as the ASES score.

Eligibility Criteria Inclusion Criteria

Age between 21 and 70 years

Diagnosis of adhesive capsulitis (frozen shoulder)

Failure of conservative treatment

Scheduled for arthroscopic capsular release surgery

Exclusion Criteria

Known peripheral neuropathy

Previous brachial plexus injury

Previous neurovascular surgery of the ipsilateral shoulder

Coagulation disorders

Active infection

Pregnancy

Inclusion Criteria:

• Age between 21 and 70 years
• Diagnosis of adhesive capsulitis (frozen shoulder)
• Persistent symptoms despite conservative treatment (e.g., physical therapy, medication, or intra-articular injections)
• Planned arthroscopic capsular release surgery
• Ability to provide informed consent

Exclusion Criteria:

• Known peripheral neuropathy
• Previous brachial plexus injury
• History of ipsilateral shoulder neurovascular surgery
• Previous proximal brachial plexus surgery
• Coagulation disorders
• Active infection
• Pregnancy