Imaging Findings

The patient is a 34-year-old male presenting with wrist pain following a bicycle accident. Routine X-ray and CT scans of the wrist were performed:

• On the X-ray anteroposterior and oblique views, a sesamoid-like structure (the hook of hamate) located on the ulnar side of the distal row of the carpal bones is not clearly visible. However, on CT coronal and axial images, abnormal morphology of the hook of hamate and discontinuity of the local trabecular bone can be observed.
• Localized swelling may appear in the surrounding soft tissue around the fractured hook of hamate, while the local joint space is still preserved.
• No obvious fracture signs were seen in other carpal bones (such as the lunate, triquetrum, or scaphoid), and there is no large-scale collapse of the bone margin.

Possible Diagnoses

Based on the imaging findings and trauma history, the following diagnoses are considered:

1. Hook of Hamate Fracture:
   Commonly seen in high-impact or compressive trauma, especially in sports involving gripping (e.g., bats or rackets). It can also result from forceful pulling or impact. CT clearly demonstrates the morphological damage to the hook of hamate.
2. Other Carpal Bone Fractures (e.g., Triquetral, Scaphoid, Pisiform):
   In cases of wrist trauma, other carpal bone fractures should be ruled out. However, CT shows no obvious discontinuity of the bone cortex in these bones.
3. Wrist Joint Soft Tissue Contusion or Ligament Tear:
   If X-ray and CT reveal no obvious fracture, soft tissue injury should be considered. However, since there is clear evidence of a hook of hamate fracture, soft tissue injury may be an accompanying pathology.

Final Diagnosis

Considering the mechanism of injury (being struck by a car), the location of pain (ulnar-side distal wrist), and imaging findings (CT showing characteristic morphological changes of a hook of hamate fracture), the most likely diagnosis is: Hook of Hamate Fracture.

If clinical symptoms persist or imaging findings are inconclusive, further MRI or a specialized hook of hamate view (Carpal tunnel view) may be used to clarify fracture details and assess any soft tissue injuries.

Treatment Plan and Rehabilitation Program

Treatment Strategy

• Conservative Treatment (Cast or Splint Immobilization):
  For non-displaced or minimally displaced hook of hamate fractures, four to six weeks of wrist immobilization can facilitate fracture healing. Early intervention often improves the healing outcome.
• Surgical Treatment:
  If the fracture is significantly displaced, involves the pisiform or the fifth metacarpal, causes potential ulnar nerve compression, or if nonunion occurs, surgical intervention such as hook excision or open reduction and internal fixation (ORIF) may be considered. Postoperative functional exercises should be guided by fracture healing progress.

Rehabilitation and Exercise Prescription

Rehabilitation should be gradual and individualized. The following outline may be considered:

1. Initial Stage (Fracture Immobilization or Early Postoperative Period, Approximately 0–2 Weeks):
   • The main goal is to protect the fracture site with wrist immobilization or splinting.
   • Perform active movements of the shoulder and elbow to prevent stiffness due to immobilization.
   • Gently flex and extend the fingers to avoid prolonged inactivity.
2. Mid-stage Rehabilitation (2–6 Weeks):
   • When the fracture stabilizes or after immobilization is removed, gradually introduce passive range-of-motion exercises and mild active exercises of the wrist.
   • Consider thermal therapy or ultrasound therapy to promote local blood circulation and tissue healing.
   • Strengthen finger grip, but avoid strong ulnar deviation or heavy resistance exercises.
3. Late Rehabilitation (6–12 Weeks or Longer):
   • Gradually increase weight-bearing exercises for the wrist using resistance bands or light dumbbells, progressing from a small range of motion to larger movements.
   • Enhance forearm muscle strength, especially the finger flexors and wrist flexors. Conduct regular check-ups to confirm fracture healing.
   • For athletes, gradually return to sports-specific training, adjusting intensity and frequency to avoid re-injury.

Example of the FITT-VP Principle:

• Frequency: 3–5 sessions per week, depending on pain and recovery status.
• Intensity: Begin at low intensity and gradually increase based on a pain-free or minimally painful scale.
• Time: 20–30 minutes per session, which can be extended to around 45 minutes in the later stages.
• Type: Active joint mobilization, mild strength training, and progressive resistance using bands or light dumbbells.
• Progression: Increase load and duration as fracture healing and wrist range of motion improve, ensuring safety and effectiveness.

Throughout rehabilitation, monitor wrist pain, swelling, and functional recovery. If discomfort or worsening pain occurs, seek medical advice promptly.

Precautions

• If delayed union or evidence of nonunion is detected, follow-up imaging should be performed promptly, and hamate hook excision or internal fixation may be considered to restore function and prevent chronic pain or ulnar nerve impingement.
• For patients requiring intense wrist activity, extend the immobilization and rehabilitation period to ensure complete fracture healing before engaging in high-intensity training.

Disclaimer: This report is provided for reference only and does not replace in-person medical consultation or professional advice. Patients should follow the guidance of a specialist or therapist for individualized treatment and rehabilitation based on their specific condition.