- Researchers at Massachusetts General Hospital reviewed a single-surgeon cohort of 163 patients who underwent reconstruction of the ulnar collateral ligament between 2009 and 2017
- A large majority of patients (88%) showed one or more tissue disruptions of the anterior bundle of the UCL, with an even balance of proximal and distal tears (46% vs. 44%)
- Chronic attritional injury to the anterior bundle was frequently observed, including areas of attenuation (61% of patients), scar tissue formation (29%) and calcifications or ossification (7%)
- In 19% of patients who had preoperative MRI, imaging didn't match the tissue disruptions observed during surgery
Athletes who engage in overhead motion or upper-extremity weight bearing, such as baseball pitchers, tennis players and gymnasts, are at increased risk of ulnar collateral ligament (UCL) injury. The UCL is located on the medial side of the elbow, and the anterior bundle (anterior band and posterior band) is the structure at risk of injury in these athletes.
PhD candidate Rik J. Molenaars, MD, and Luke S. Oh, MD, orthopaedic surgeon, of the Sports Medicine Center at Massachusetts General Hospital, and colleagues recently conducted a study of the pathoanatomy of UCL injury. In the Journal of Shoulder and Elbow Surgery, they emphasize the variety of possible injury characteristics and the high prevalence of attritional chronic injury.
The researchers retrospectively reviewed operative notes on 163 patients who had UCL reconstruction performed by Dr. Oh between 2009 and 2017. The cohort was predominantly white and male, and 93% of the patients were high school or college baseball players.
Types of Injury
The researchers classified the anterior bundle injuries into five subgroups according to the presence and pattern of tissue disruption:
- No disruption — 12%
- One disruption — single tear (60%) or single perforation (5%)
- Multiple disruptions — more than one tear (16%) or tear plus perforation (7%)
There was an even balance of proximal and distal tears (46% vs. 44%). Areas of attenuation (61% of patients), scar tissue formation (29%) and calcifications or ossification (7%) were frequently observed, suggesting acute-on-chronic injury.
A popping sensation was reported by 29% of the patients. Popping was the only patient characteristic that was significantly different among the five subgroups; it was significantly more common among patients who had single tears (39%) than in patients with non-tear insufficiency (5%) (P = .03).
The other characteristics considered were age, time to surgery, acute vs. nonacute onset of injury, previous shoulder or elbow injury and history of osteophyte removal.
Description of Tears
Ten percent of patients had a complete or nearly complete rupture of the anterior bundle. In addition, 52% of patients had a full-thickness or nearly full-thickness tear. Distal tears more frequently affected the anterior band of the anterior bundle, and the posterior band was more frequently vulnerable in proximal tears (P = .01).
Comparison with MRI
Preoperative MRI data were available for 153 patients. For 124 of them (81%), the MRI findings matched what the surgeon later observed about the presence and location of tissue disruption. Of the 29 cases of mismatch, 23 involved a tear being observed on MRI whereas surgical inspection revealed only tissue thinning or degeneration.
Future investigations should attempt to better correlate preoperative imaging with the various manifestations of injury to the anterior bundle of the UCL.
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