Effect of Plane of Arm Elevation on Glenohumeral Kinematics

Authors:

J Erik Giphart, John P Brunkhorst, Nils H Horn, Kevin B Shelburne, Michael R Torry, Peter J Millett

Abstract:

Understanding glenohumeral motion in normal and pathologic states requires the precise measurement of shoulder joint kinematics. Multiple studies have linked abnormal shoulder joint kinematics with various shoulder disorders including secondary impingement, rotator cuff tears, glenohumeral osteoarthritis, labral injury, and glenohumeral instability.

Although shoulder pathology is associated with abnormal kinematics, there is little detailed information about baseline values that can provide reference points for the restoration of normal shoulder kinematics. The most commonly studied parameter for glenohumeral rotation is scapulohumeral rhythm, defined as the ratio between glenohumeral elevation and upward scapulothoracic rotation, which was first reported to be 2:1 by Inman. Two types of abnormalities in scapulohumeral rhythm have been recognized in shoulders with pathologic conditions: (1) increased rhythm exacerbating the likelihood of secondary impingement by biomechanically decreasing the volume of the subacromial space, and (2) decreased rhythm serving as a compensatory method that potentially avoids impingement symptoms and improves rotator cuff function.

There is considerable variation in the magnitude of physiologic glenohumeral translations reported in the literature. Normal in vivo glenohumeral translations ranging from 0.3 to 2.6 mm in the superior-inferior direction have been demonstrated by means of dynamic measurements involving fluoroscopy and static measurements involving radiography. Normal in vitro superior shoulder translations of 2.0 to 5.7 mm have been reported. Increased mean in vivo glenohumeral translations of approximately 1.5 mm in patients with symptomatic rotator cuff tears, impingement syndrome, and biceps tenodesis have been reported, with individual increases of up to 6 to 8.9 mm.

In recent years, biplane fluoroscopy has emerged as a highly accurate and precise method to measure in vivo three-dimensional kinematics; this method allows measurement of glenohumeral joint motion to within fractions of a millimeter. Clinically, measurement of the full range of arm elevation is important because arm elevation is a common motion during activities of daily living and athletic activities. It is uncommon for shoulder kinematics in fluoroscopic studies to be reported in all three of the standard planes of arm elevation: abduction (coronal plane elevation), scaption (scapular plane elevation), and forward flexion (sagittal plane elevation). As a result, the relative effect of the plane of elevation on glenohumeral translation and scapulohumeral rhythm remains unknown. Our purpose was to measure three-dimensional glenohumeral translations and rotations during abduction, scaption, and forward flexion in healthy subjects. Our hypothesis was that glenohumeral translations and scapulohumeral rhythm would change with the plane of elevation.

For the complete study: Effect of Plane of Arm Elevation on Glenohumeral Kinematics

Peter Millett, MD

Average rating:

39 reviews

Alexandra Thompson

Mar 23, 2024

by Alexandra Thompson on Peter Millett, MD

110%

Dr. Millett and his team did a SLAP tear repair and bicep tenodesis on my left shoulder. I use my arms as an artist, and love to swim in the ocean, surf, paddle, and telemark ski. So regaining full use of my shoulder and keeping my bicep attached was very important to me. Now, over two years later, my shoulder has the equivalent range of motion as my other arm and as before the injury, and no pain. After the first three months it felt so good and was so strong that - to my horror - I completely forgot my six-month follow-up.

Not only did Dr. Millett and his team make my arm as good as new, but having had the experience of such kindness and expertise throughout the process of surgery and recovery is like an added shoulder superpower.

Thank you Rita, Brooke, Jason, Sarah, Camille, Olivia, Dr. Millett and everyone! And see you soon when my husband comes in for his knee...

Jeff Chandler

Jan 31, 2022

by Jeff Chandler on Peter Millett, MD

Flawless procedure, Easy recovery

Dr. Millet's repaired my knee and tibia, following a botched operation by a different surgeon. That procedure was virtually pain free and I was weight bearing within a few days. That was 18 years ago and the knee is still strong. A few years after the knee incident, Dr Millet repaired my shoulder. My insurance company approved me for 3 months of disability following that surgery. I was off pain medication in 2 days and had 90% range of motion within a week. I withdrew my disability claim and returned to work within two weeks of surgery. I’m not a famous athlete—just a regular guy. Nonetheless, I was treated like an NFL at the Steadman clinic. Most notable was the time for recovery. Other surgeons perform their hour-long task in the OR and don’t involve themselves in the other functions. Peter and his team manages the entire process from diagnosis, anesthesia, nursing care, and therapy. He takes a holistic approach to patient care and doesn’t skip any steps.

Jenn West

Jul 2, 2021

by Jenn West on Peter Millett, MD

Saved My Life

I went to Dr. Millett after 7 knee surgeries (6 on my right and 1 on my left) and had seen 11 different surgeons who all refused to remove femur metal from my right leg. I am highly allergic to metal and the chronic pain was leaving me bedridden for 3.5wks out of a month. He personally wrote me back on my inquiry, listened to my concerns, scheduled my surgery within a week (due to insurance issues) and personally followed up with my recovery. The level of patient care from Dr. Millett and his ENTIRE team is above any care I have ever received in my 20 years of dealing with orthopedic surgeons. There are not enough words to describe the level of care, dedication and professionalism you receive from Dr. Millett and his staff.
My only disappointment is that I did not find him sooner!!!

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