Metacarpophalangeal Joint Injuries: Fractures (Intraarticular) at the Base of the Proximal Phalanx, An Arthroscopic Technique

43 Metacarpophalangeal Joint Injuries: Fractures (Intraarticular) at the Base of the Proximal Phalanx, An Arthroscopic Technique

Joseph F. Slade III and John D. Mahoney

History and Clinical Presentation

A 20-year-old varsity football player sustained an avulsion fracture of the index finger when he struck his hand against another player’s helmet. The patient presented to the trainer at the end of the game, complaining of pain and swelling at the base of the index metacarpophalangeal (MP) joint.

Physical Examination

Point tenderness was noted at the base of the proximal phalanx, with moderate swelling. The patient had reduced range of motion of the MP joint, and a stress exam elicited significant pain.

Diagnostic Studies

Standard radiographs identified a displaced intraarticular fracture of the base of the proximal phalanx involving 50% of the articular surface. Had there been any question regarding laxity of the collateral ligaments, stress radiographs would have been appropriate. The special indications for further studies are detailed in Table 43–1.

PEARLS

Implants deep in bone permit early restoration of motion without risk of secondary inflammation or tendon rupture due to rubbing of soft tissue or tendon on prominent hardware.
The same techniques of percutaneous fixation of intraarticular fractures can be applied to extraarticular fractures as well.

PITFALLS

Knowledge of neurovascular anatomy is essential to avoid injury when placing arthroscopy portals and when driving K wires.
Care must be taken to limit traction time to less than 2 hours.

**Table 43–1** **Diagnostic Studies and Their Indications**
Modality	Application	Comments
Plain radiographs (posteroanterior, lateral, and oblique)	Capable of diagnosing most fractures and dislocations of the hand
Stress radiographs	Used for defining ligamentous laxity (e.g., gamekeepers’ thumb)	When fracture is not evident on standard views
Bone scans	Can detect increased activity in the joint, suggestive of an osteochondral defect	Nonspecific study
Computed tomography scan, aligned in sagittal plane	Used for defining the step-off of intraarticular fractures
Magnetic resonance imaging	Used for ulnar collateral ligament injuries in the thumb	Most sensitive in detecting the Stener lesion