In vivo changes in length of elbow collateral ligaments during pronation and supination on an outstretched arm.

PURPOSE: This study investigated the length changes of the anterior bundle of the medial collateral ligament (AMCL) and the lateral ulnar collateral ligament (LUCL) in forearm pronation and supination under axial load in vivo.

METHODS

Six healthy volunteers (2 males and 4 females, the average age of 44.6 years) were included in the study. CT scan of elbow joints was obtained at positions of forearm pronation and supination before and after load with the elbow extension. Mimics, Geomagic Studio, 3-matic Medical and Geometry Sketchpad were used to reconstruct three-dimensional models and analyze length changes of AMCL and LUCL. The AMCL and LUCL were divided, respectively, to three parts: the medial part, the middle part and the lateral part.

RESULTS

Our results showed the length of the medial and middle parts of the AMCL significantly decreased from pronation to supination without load (0.46 mm, P < 0.05 and 0.43 mm, P < 0.05). With load, the length of the medial part and the middle of the AMCL significantly decreased from pronation to supination (0.62 mm, P < 0.05 and 0.44 mm P < 0.05). However, the length of the LUCL almost remained static for the forearm pronation and supination regardless of the axial load.

CONCLUSION

The results showed that tension of the AMCL increases in forearm pronation, and increased tension on the ligament during impact may pave the way to injury. The AMCL of elbow may be easier to be injured in forearm pronation.