Boutonniere deformity of ring finger

This patient was in his late 20’s and presented with a right ring finger stuck in a flexed posture.

He had a rugby injury 6 months ago when his finger was caught in someone’s jersey. At the time he thought it was just a sprain so he did not seek medical advice. However, over time he was unable to straighten the finger and it developed a deformity of flexion at the PIPJ and hyperextension at DIPJ.

He regularly knocked the finger as it got in the way especially when he was getting dressed or putting his hand in his pocket. Due to the flexed posture, it was also at risk of re-injury.

Examination:
The PIPJ was stuck in flexion, and it was not correctable by moving the joint. There was some give in the joint which meant there was potential for it to be corrected. It was evident that there was a disruption of the mechanism of tendons/ligaments that straightens the joint.

Due to the complexity of the finger joints, there was a muscle/tendon imbalance between the two joints that caused the deformity.

Treatment:
Serial plaster casting was used to gradually reduce the fixed flexion contracture at the PIPJ. This was done by placing the soft tissue on gentle tension over a prolonged period of time.

Once the joint was straight, the function of extensor tendon could then be fully assessed. As the tendon was intact, the tendon/muscle imbalance could be restored by further splinting.

An exercise programme followed to re-establishing the tendon glide and stretching tight ligaments.

Towards the end of the treatment, a relative motion splint was made which the patient wore in function to retrain the synergy between the flexor and extensor tendons.

Gradually the patient regained a finger that was almost fully straight and with a good degree of flexion to be functional.