1. Radiological Findings

Based on the provided X-ray and CT images, a postoperative internal fixation of the right forearm radius and ulna fracture is observed. The fracture ends have been stabilized with internal fixation (including nails or pin-like implants), and the fracture alignment appears generally acceptable.
However, in the wrist area and the adjacent region between the bases of the 2nd to 5th metacarpals and the corresponding carpal bones, there is visible articular surface displacement, indicating abnormal alignment between the distal metacarpals and the corresponding carpal bones. On lateral and some coronal CT reconstruction images, noticeable displacement of the metacarpal bases can be seen, along with local soft tissue swelling, irregular joint spacing, and discontinuous articular surfaces, suggesting a dislocation or subluxation of the carpometacarpal joints (CMJ).
Additionally, there is swelling of muscles and soft tissues, with increased density around the joint, which may be related to persistent inflammatory responses or soft tissue injury. No clearly new and significant fracture lines are identified, but minor bony irregularities and small bone fragments may be present, requiring careful comparison of different sequence images. MRI (if available) could further indicate ligament injuries, but based on CT and X-ray findings, a CMJ dislocation and associated ligament damage are highly suspected.

2. Potential Diagnoses

1. Carpometacarpal (CMJ) Dislocation/Subluxation: The visible misalignment between the bases of the metacarpals and the carpal bones is the primary consideration. Given that the patient has postoperative pain, joint dysfunction, and imaging findings consistent with a traumatic mechanism, a high level of suspicion is warranted.
2. Wrist Joint Instability or Ligament Injury: If imaging suggests an abnormal joint alignment, it might be severe ligament damage leading to joint instability. However, given the pronounced displacement of the articular surfaces, dislocation is more likely.
3. Fracture Nonunion or Malunion Leading to Secondary Joint Instability: Although the radius and ulna fracture alignment appears acceptable in the provided images, it is still important to rule out malhealing of the distal fracture segments causing instability. Nonetheless, the current findings lean more toward CMJ dislocation.

3. Final Diagnosis

Considering the patient is a 39-year-old male with a history of radius and ulna fracture surgery 5 months ago, who now presents with persistent pain, limited function, and local swelling, and given the significant misalignment of the wrist and carpometacarpal joint surfaces observed on multi-plane imaging (X-ray and CT), the most likely final diagnosis is:

Right Wrist Carpometacarpal (CMJ) Dislocation (Predominantly Dorsal)

Since it was identified 5 months post-injury, this is considered a relatively late diagnosis, potentially classified as a chronic dislocation.

4. Treatment Plan and Rehabilitation

(1) Treatment Strategy

• Surgical Treatment:
  • For chronic or more than 3-week-old CMJ dislocations, open reduction (OR) is often considered.
  • A dorsal longitudinal incision is typically used during surgery, allowing for the removal of any bone fragments or osteochondral debris from the joint. Once anatomical reduction is achieved, the joint is stabilized with Kirschner wires (K-wires) or other internal fixators.
  • If there is severe comminution of the articular surface, a partial arthrodesis may be performed, though it can result in reduced joint mobility.
• Conservative Treatment: For very early stages (within 1–2 weeks) or mild subluxation, closed reduction under fluoroscopy followed by casting or bracing can be attempted. However, in this case, given the 5-month delay, the success rate is relatively low.
• Postoperative Management: Regular X-ray follow-ups are required to monitor alignment and prevent recurrent dislocation. Usually, K-wires are removed at around 6 weeks, followed by gradual initiation of functional exercises.

(2) Rehabilitation and Exercise Prescription

Rehabilitation should follow a gradual, individualized plan. Stabilization of bones and joints is prioritized, followed by progressive restoration of joint flexibility and muscle strength to prevent muscle atrophy and joint contracture:

• Early Phase (0–6 weeks):
  • Immobilization and Protection: Use appropriate braces or splints to maintain proper wrist positioning.
  • Finger Flexion and Extension and Light Grip Exercises: Within allowable limits, perform exercises 2–3 times per day, each session lasting about 5–10 minutes, avoiding excessive traction on the joint.
• Intermediate Phase (6–10 weeks):
  • After K-wire removal, progressively increase active wrist range of motion exercises, such as gentle flexion, extension, and forearm rotation.
  • Apply the FITT-VP principle: Train 3–5 times per week, 10–15 minutes per session, gradually increasing the range of motion and repetitions within a pain-free range.
  • Heat therapy or ultrasound therapy may be used to promote soft tissue healing.
• Late Phase (from 10 weeks onward):
  • Introduce Resistance Training: Use elastic bands or small dumbbells to strengthen forearm muscles and improve grip strength.
  • Gradually Resume Functional Activities: Enhance wrist coordination and flexibility, practicing detailed movements necessary for daily life and occupational tasks.
  • Monitor wrist response closely. If significant pain or swelling persists, reduce or pause activities and consult a specialist.

5. Disclaimer

This report is a reference analysis based on available imaging and clinical information and does not replace an in-person examination or professional medical advice. Specific treatment plans should be tailored to the patient’s condition and carried out under the supervision of qualified medical professionals.