Unit
- Carpal bones: The wrist contains eight carpal bones arranged in proximal and distal rows. The scaphoid, lunate, triquetrum, and pisiform form the proximal row; the trapezium, trapezoid, capitate, and hamate form the distal row. Understanding their articulations is essential for fracture classification and reconstruction planning.
- Metacarpals and phalanges: Five metacarpals connect the carpus to the proximal phalanges. Each finger has three phalanges (proximal, middle, distal) while the thumb has two. The joint surfaces are covered with articular cartilage; ligamentous support provides stability during grip and pinch.
- Wrist joint kinematics: The radiocarpal and midcarpal joints allow flexion-extension, radial-ulnar deviation, and circumduction. The scapholunate and lunotriquetral ligaments are critical for stability. Disruption in these ligaments leads to carpal instability patterns that require reconstruction.
- Bone blood supply: The distal radius and carpal bones receive blood from the radial and ulnar arteries via a rich anastomotic network. The scaphoid has a retrograde blood supply, making proximal pole fractures prone to avascular necrosis. Surgeons must consider vascular territories when planning osteotomies.
- Joint congruity: Articular surfaces must be precisely reduced to prevent posttraumatic arthritis. Intra-articular fractures of the distal radius or phalanges require anatomic reduction and stable fixation to restore cartilage gliding and avoid stiffness.
- Growth plates: In pediatric patients, the physis (growth plate) is the weakest structure in the skeletal chain. Salter-Harris fracture classification guides management; injury to the physis can cause growth arrest and angular deformity, necessitating long-term follow-up.
- Fracture healing: Bone healing in the hand occurs through primary (direct) or secondary (callus) healing depending on fixation stability. Rigid internal fixation with plates and screws promotes primary healing, while external immobilization relies on callus formation to restore continuity.
- Reconstruction principles: Skeletal reconstruction aims to restore length, alignment, rotation, and joint function. Techniques include open reduction internal fixation, external fixation for comminuted fractures, and bone grafting for defects. The choice depends on fracture pattern, soft tissue condition, and patient factors.
- Bone grafting: Autograft from the distal radius, iliac crest, or allograft options are used to fill bone defects from comminution, nonunion, or tumor resection. Cancellous grafts provide osteoconductive and osteoinductive properties, while corticocancellous grafts offer structural support. Surgeons select grafts based on defect size, location, and vascularity.
- Implant considerations: Kirschner wires, lag screws, plates, and intramedullary devices are commonly used for hand fracture fixation. Low-profile plates minimize soft tissue irritation. The choice depends on bone size, fracture stability, and whether early motion is desired. Bioabsorbable implants are emerging for pediatric cases to avoid secondary removal.
- Fracture patterns: Common hand fractures include distal radius, scaphoid waist, boxer's fractures of the fifth metacarpal neck, and phalangeal shaft fractures. Each pattern has unique biomechanical considerations and fixation strategies. For example, intra-articular fractures require anatomic reduction to prevent stiffness, while extra-articular fractures may be managed conservatively.
Terminology
- Osteotomy
- A surgical cut made through a bone to correct deformity or to allow realignment.
- Avascular necrosis
- Death of bone tissue due to loss of blood supply, often complicating scaphoid proximal pole fractures.
- Salter-Harris classification
- A system categorizing physeal fractures into five types to predict growth disturbance risk.
Quick Revision
- The hand skeleton comprises 27 bones: 8 carpals, 5 metacarpals, 14 phalanges.
- Carpal instability often arises from scapholunate ligament tears.
- Scaphoid fractures risk avascular necrosis due to retrograde blood supply.
- Pediatric growth plate injuries require Salter-Harris classification for management.
- Reconstruction goals include anatomic alignment and stable fixation to preserve joint function.
Disclaimer
Educational use only. Not intended for practical surgery, incisions, or other surgical procedures. It does not qualify you to perform physical operations.