Correlation between extension-block K-wire insertion angle and postoperative extension loss in mallet finger fracture

Area of Science:

• Orthopedic Surgery
• Hand Surgery
• Fracture Management

Background:

• Extension-block pinning is a common technique for mallet finger fractures.
• Postoperative extension loss can occur despite successful procedures.
• The optimal Kirschner wire (K-wire) insertion angle for minimizing this complication is not well-established.

Purpose of the Study:

• To investigate the relationship between the K-wire insertion angle and postoperative extension loss in mallet finger fractures.
• To evaluate other operative and non-operative factors influencing extension loss after extension-block pinning.

Main Methods:

• Retrospective study of 75 patients with mallet finger fractures treated with extension-block pinning.
• Analysis of immediate postoperative and latest follow-up lateral radiographs.
• Measurement of K-wire insertion angle, distal interphalangeal (DIP) joint fixation angle, and postoperative extension loss.

Main Results:

• A negative correlation was found between K-wire insertion angle and extension loss (r=-0.66).
• Higher K-wire insertion angles (>40°) significantly reduced postoperative extension loss compared to medium angles (30°-40°), with a mean difference of 11°.
• Positive correlations were observed between fracture size and time to operation with extension loss.

Conclusions:

• An extension-block K-wire insertion angle of 40°-45° may help minimize postoperative extension loss.
• Achieving a slightly hyperextended DIP joint position during fixation is also beneficial.