CASE 10656 Published on 29.04.2014

Stener lesion

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Pilavas Polykarpos, Nicolaou Christophoros, Constantinou Yiorgos, Paraliki Lamprini, Christodoulou Loizos

Aretaeio Hospital,Radiology Dpt; Vonis 10 2114 Nicosia, Cyprus; Email:polys4@yahoo.gr
Patient

44 years, male

Categories
Area of Interest Musculoskeletal soft tissue ; Imaging Technique MR, Image manipulation / Reconstruction
Clinical History
44 year male patient visits orthopedic surgeon with pain at the left thumb base area, after injury (fall on open hand). There was swelling of the soft tissues at the medial part of the base of the thumb. After clinical examination the surgeon requested an MRI scan.
Imaging Findings
The images show the retracted UCL resulting in the yoyo on a string appearance. The yoyo represents the rolled up and retracted UCL, whilst the string of the yoyo is the adductor aponeurosis. There is abundant oedema at the soft tissue. No bony avulsion recognized at the area.
Discussion
The ulnar collateral ligament (UCL) connects the ulnar aspect of the first metacarpal and the proximal phalanx of the thumb and functions as a major stabilizer of the first metacarpophalangeal joint. Ulnar collateral ligament injuries of the thumb are frequent injuries encountered by the orthopaedic surgeons 1.
The term gamekeeper's thumb was first used by Campbell in 1955 when he described a high prevalence of incompetence of the ulnar collateral ligament among Scottish gamekeepers who used twisting techniques for killing rabbits 2. This type of injury is also met in skiers, given the alternate name ‘skier’s thumb’, even though it is considered a rather acute injury for the latter and a chronic injury for the former 3.
The mechanism of the injury is abrupt radial stress to the UCL like a skier gripping a ski pole during a fall with the thumb in abduction.
At clinical examination there is inability of grasping activities between the thumb and the second digit and laxity with valgus stress.
The differentiation of non-displaced ulnar collateral ligament tear from displaced tear (or Stener lesion) is important, as surgery is required in the latter to avoid chronic instability and possible joint degeneration 4.
Imaging is therefore requested to establish the diagnosis, help the surgeon to decide whether to operate or not and as a guidance map for the probable surgery. Ultrasound and MRI scan can both be used to examine the base of the thumb with equal efficacy at diagnosis 5. The choice of the appropriate modality depends on the availability of the appropriate modules (e.g. high frequency linear transducer, hand surface coil), the experience of the ultrasonographer and the availability of the machine at a tight schedule (mostly for the MRI).
MRI demonstrates the yo-yo on a string appearance, the string represented by the adductor aponeurosis and the retracted UCL representing the yo-yo ball 6. However chronic injury of the ligament can result in a proximally retracted UCL deep to the adductor aponeuvrosis, which can be confused with a Stener lesion 3.
The outcome of the early fixation of the lesion is very good, resulting in good stability with only slight decrease in motion 7.
It is important to state out that in Stener lesion that the ulnar collateral ligament is transpositioned superficial to the adductor aponeurosis, therefore the ligament ends are no longer in contact and will not heal conservatively.
Differential Diagnosis List
Disruption of the ulnar collateral ligament with Stener lesion
Non displaced ulnar collateral ligament tear
Fracture of the base of the proximal phalanx of the thumb
Dorsal hood injury
Thenar muscle injury
Final Diagnosis
Disruption of the ulnar collateral ligament with Stener lesion
Case information
URL: https://www.eurorad.org/case/10656
DOI: 10.1594/EURORAD/CASE.10656
ISSN: 1563-4086

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