Age / Sex : 28 / M

Chief complaint: right elbow pain

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 홍석주(Hong Suk-Joo), 고려대구로병원(Korea university Guro Hospital)

Posterolateral rotatory instability

Discussion

Findings:

High grade partial tear of medial epicondylar and
olecranon insertion site of anterior band MCL, with compressing overlying ulnar
nerve, suggesting combined ulnar nerve injury.

Complete tear of lateral epicondylar insertion site
of RCL and LUCL, with posterolateral capsular distension.

Posterior subluxation of radial head.

Diagnosis: Posterolateral rotatory instability

Discussion:

 Posterolateral
rotatory instability

•      Clinical manifestation

–     Painful clicking or locking of the elbow

–     Occur in the extension

•      Caused by,

–     Trauma (varus stress, posterior dislocation)

–     Iatrogenic, chronic overuse, generalized ligament
laxity…

•      Secondary to tear of the LUCL

–     Usually occur at the humeral insertion

–     Posterior subluxation of the radial head

–     Secondary rotatory subluxation of the humero-ulnar
joint

•      3 stage circle-like soft-tissue disruption (Horii
circle)

–     Stage 1:

•      Disruption of the LUCL

•      Posterolateral subluxation of the elbow

–     Stage 2:

•      Disruption of the ant & post capsule

•      Incomplete posterolateral dislocation

–     Stage 3:

•      Disruption of the MCL

•      Varus, valgus, and rotatory instability

•       MRI :

–     Focal discontinuity of ligamentous fibers or intraligamentous
high T2 signal intensity of LUCL, RCL and/or MCL.

–     Surrounding edema

–     Posterior subluxation of the radial head on
sagittal images

•      Treatment

–     Surgical intervention

–     Repair or reconstruction of the torn or deficient
LUCL

References:

1. Posterolateral Rotatory Instability of the Elbow, J Am Acad
Orthop Surg 2004;12:405-415

2. Magnetic
Resonance Imaging of the Elbow, J Magn Reson Imaging 2010;31:1036–1053