Frank (2015) — Posterior Shoulder Instability in Athletes

Posterior Shoulder Instability in Athletes

·JBJS Rev·2015·6 citations·Shoulder & Elbow

This narrative review covers posterior shoulder instability in athletes. It synthesizes the anatomy, biomechanics, physical exam, imaging, and treatment options for this uncommon instability pattern. The focus is on contact and overhead athletes and how to diagnose and manage their posterior labral and capsular lesions.

Key Findings

Posterior instability represents up to 10% of all shoulder instability. In athletes it usually arises from direct trauma in contact sports or repetitive microtrauma from overhead play, rarely from atraumatic causes.
The provocative position is flexion, adduction, and internal rotation. This maximally tensions the thin posterior band of the inferior glenohumeral ligament, which is why football linemen blocking and batters missing outside pitches are at risk.
A painful jerk test is 90% sensitive and 85% specific for posterior labral lesions. More importantly, it predicts nonoperative failure: 86% failure with a painful jerk versus 7% with a painless jerk (p<0.001). A painful jerk should push you toward surgery.
Combining the Kim and jerk tests reaches 97% sensitivity for posteroinferior labral tears.
–Kim test alone: 80% sensitive, 94% specific
–Jerk test alone: 73% sensitive, 98% specific
MRA is the most sensitive study for detached labral fragments (96%), and adding intra-articular contrast on 3-T MRI raises posterior labral tear detection from 78% to 89% and from 84% to 95%. CT is used to quantify glenoid bone loss.
The Kim classification stages posteroinferior labral lesions:
–Type I: separation without displacement
–Type II: incomplete avulsion (the concealed Kim lesion)
–Type III: loss of labral contour
Arthroscopic capsulolabral reconstruction gives high return-to-play but is less effective in throwers. Radkowski reported 55% return to preinjury level in throwers vs 71% in nonthrowers, reflecting the higher demands on the throwing shoulder.
Conservative rehab succeeded in 94% (15/16) of atraumatic patients but only 36% (4/11) with a traumatic history and osseous defects. Bone-block augmentation is reserved for glenoid deficiency exceeding 25%.

Board PearlCombining the Kim and jerk tests reaches 97% sensitivity for posteroinferior labral tears, and a painful jerk predicts nonoperative failure.

Clinical Relevance

When an athlete reports pain while blocking, decreased pitching velocity, or fatigue during push-ups and bench presses, think posterior instability rather than the more familiar anterior pattern.

Your exam anchors the workup. A painful jerk test is not just diagnostic, it is prognostic: these patients fail rehab 86% of the time, so a painful jerk should lower your threshold for surgery. Pair it with the Kim test to reach 97% sensitivity. Order MRA for the labrum and capsule, and add CT when you suspect osseous injury or need to quantify glenoid bone loss.

The management algorithm is soft tissue versus bone. Start most patients with periscapular and rotator cuff rehab. Reserve arthroscopic capsulolabral reconstruction for failed conservative care, and remember throwers do worse than nonthrowers. Bone-block augmentation is for glenoid deficiency over 25%.

This remains a less-studied instability pattern, so the evidence base is largely case series rather than randomized data.

Supplemental

Posterior Shoulder Instability in Athletes

Chauhan, Frank, et al.·JBJS Rev·2015·6 citations·Shoulder & Elbow

Posterior Shoulder Instability in Athletes

Key Findings

Clinical Relevance

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