A 37-year-old male presented with a left thumb injury after falling on an outstretched left hand while playing football. He presented with pain and instability of the left thumb metacarpophalangeal (MCP) joint, which was impacting his ability to grip, and affecting his daily life and work.
On MRI images (Figures 1, 2 and 3), there is a complete rupture of the ulnar collateral ligament (UCL) of the left thumb MCP joint. A portion of the UCL is retracted and displaced over the adductor aponeurosis. This represents a “yo-yo on a string” appearance on MRI, in which the yo-yo is the torn and displaced UCL, and the string is the adductor aponeurosis [1].
Normally, the UCL lies deep to the aponeurosis of the adductor pollicis muscle. A Stener lesion represents a specific type of injury that occurs in the thumb with forceful abduction, characterised by a complete tear of the UCL with interposition of the adductor aponeurosis between the MCP joint and retracted UCL [2]. The Stener lesion is a subset of the gamekeeper’s thumb or skier’s thumb [1,3].
The UCL is an important stabilising ligament of the thumb, providing stability during pinching and gripping [4]. Patients with Stener lesions usually present with a history of a traumatic event, such as a fall or direct blow to the thumb. They may experience immediate pain, swelling, and difficulty using the thumb. On physical examination, there is often tenderness over the ulnar aspect of the thumb MCP joint, and the thumb may exhibit instability or gapping with stress testing [3].
Imaging is crucial in the evaluation of a suspected Stener lesion. Radiographs are usually the initial imaging modality performed to rule out associated fractures. However, they may not reveal the Stener lesion itself. Additional imaging such as ultrasound or MRI is often necessary.
Ultrasound can be used to directly assess the integrity of the UCL. It can demonstrate the presence of a Stener lesion by showing a gap between the torn ends of the ligament, with interposition of the adductor aponeurosis or other soft tissues.
MRI is a valuable imaging tool for evaluating Stener lesions. It provides a detailed visualisation of the UCL and surrounding structures, allowing for an accurate assessment of the ligament integrity. MRI can clearly depict the Stener lesion as discontinuity of the UCL fibres with interposition of the adductor aponeurosis. The Stener lesion is usually seen well on coronal sequences with small field-of-view [1,3].
The treatment of Stener lesions typically involves surgical intervention. Conservative management is unlikely to promote adequate healing because the severed end of the ligament becomes entangled by the adductor aponeurosis. Surgery involves repairing the torn UCL and addressing any associated injuries [5]. Our patient underwent surgical repair of the UCL and K-wire stabilisation of the MCP joint. The K-wires were removed after one month with satisfactory healing.
Take Home Message
The Stener lesion is an important injury that can occur around the MCP joint of the thumb. The clinical presentation includes pain, swelling, and instability of the thumb after a traumatic injury. Imaging, such as ultrasound or MRI, is necessary to confirm the diagnosis. Prompt and accurate imaging diagnosis is crucial for surgical planning and treatment decisions.
All patient data have been completely anonymised throughout the entire manuscript and related files.
Stener lesion of the thumb with complete UCL tear and retraction
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Based on the provided MRI sequence images, there is a clear discontinuity of the ulnar collateral ligament (UCL) at the left thumb metacarpophalangeal (MCP) joint. An intervening soft tissue shadow (possibly the adductor aponeurosis or related structures) is visible between the torn ends of the ligament, suggesting a rupture with significant separation. Localized soft tissue swelling is observed, as well as a small amount of effusion around the joint. No obvious fracture lines or bony abnormalities are noted.
Taking into account the patient’s trauma history (excessive abduction load on the thumb), local instability, and MRI findings (a ruptured ligament with visible soft tissue interposition), the most likely diagnosis is an ulnar collateral ligament rupture with a Stener lesion. This conclusion is highly consistent with the clinical symptoms, physical examination (instability at the thumb MCP joint), and imaging findings.
1. Treatment Strategy
- Surgical Treatment: Stener lesions typically require surgical repair, as interposed soft tissue (e.g., the adductor aponeurosis) prevents the torn ends of the ligament from healing properly with conservative management. Surgical repair or reconstruction of the torn UCL may be performed, and in some cases, joint fixation (e.g., with K-wires) may be considered to aid healing.
- Postoperative Protection: After surgery, a splint or cast is usually applied to protect the thumb MCP joint for a specific period, preventing re-injury or re-tearing of the ligament.
- Conservative Treatment: If the UCL tear is mild or partial and not complicated by a Stener lesion, a splint and functional exercises may suffice. However, for a confirmed Stener lesion, conservative treatment is generally not recommended.
2. Rehabilitation and Exercise Prescription
- Early Stage (0–4 weeks post-op): Keep the thumb MCP joint immobilized to limit abduction and valgus movements, preventing reinjury. Encourage non-weight-bearing, pain-free active flexion and extension of other fingers and the wrist to maintain general range of motion.
- Intermediate Stage (4–8 weeks post-op): Gradually remove or reduce external immobilization under professional guidance. Begin gentle passive and active exercises for the thumb MCP joint, with a progressive increase in intensity. Initiate light gripping and pinching exercises (e.g., using a soft ball or light hand exerciser), carefully monitoring pain levels.
- Later Stage (8–12 weeks post-op): Gradually add resistance-based exercises and functional training (e.g., picking up small objects, twisting bottle caps, handwriting). Progressively reintroduce light work or sports activities, depending on recovery.
- Long-Term Follow-Up: Following the FITT-VP principles (Frequency, Intensity, Time, Type, Progression, and individualization), begin each exercise session with low intensity and short duration, then gradually increase. If pain, swelling, or motion limitations occur, consult a healthcare professional and adjust the rehabilitation plan accordingly.
This report is based solely on the available imaging and patient history and is intended to provide academic and clinical reference. A definitive diagnosis and treatment plan require comprehensive clinical evaluation and in-person consultation with a qualified physician. This report does not replace formal medical diagnoses or treatment advice, and individuals should follow the guidance of healthcare professionals for further management.
Stener lesion of the thumb with complete UCL tear and retraction
