Intramedullary Screw Fixation of the Fifth Metatarsal: An Anatomic Study and Improved Technique

Abstract

Intramedullary screw fixation has been found to be a reliable treatment for certain fractures of the fifth metatarsal. Techniques for this treatment have been described relying largely on intraoperative fluoroscopy. Ten human cadaver specimens had their fifth metatarsals osteotomized and underwent retrograde intramedullary pin placement. Anatomic landmarks and the location of the sural nerve in relation to this starting point were measured. The trajectory of a pin reducing the osteotomy was analyzed. Using the resultant starting point and guide pin trajectory, intramedullary screw placement was performed reliably without the aid of fluoroscopy. This study demonstrates that intramedullary screw fixation of proximal fifth metatarsal fractures may be performed with the use of anatomic landmarks, which decreases the amount of intraoperative fluoroscopy needed.

Evaluation of Two Types of Intramedullary Jones Fracture Fixation in a Cyclic and Ultimate Load Model

“…Surgical preparation of the intramedullary canal was carried out according to the manufacturer's proposed technique. A 2.0 mm guide wire was inserted “high and inside” by direct visualization and orientation, inspired by previously published anatomical landmarks . Afterward a 3.5 mm drill guide was introduced over the guide wire and a 3.5 mm cannulated drill was advanced into the proximal aspect of the fifth metatarsal.…”

“…The steel cups were mounted in a machine vice that is fixed to an adjustable platform. The fifth metatarsal was aligned such that the plantar surface was directed upwards with a slight angulation of 7–10° plantarflexion, mimicking the fifth metatarsal stacking angle . A fixed self‐leveling horizontal laser beam (PLL 360; Robert Bosch GmbH, Leinfelden‐Echterdingen, Germany) and a goniometer were used for alignment verification during mounting.…”

“…However, certain athletes are prone to failure, possibly due to increased physical demands, repetitive stresses, and inadequate initial fixation. Reported failure of intramedullary screw fixation includes delayed union, non‐union, and refracture associated with screw failure, especially in basketball, football, and soccer players . Several screw designs have been used to treat Jones fractures.…”

“…Cannulated screws provide an easy insertion technique but might bear detrimental biomechanical behavior compared with solid screws . Solid screw insertion can be technically demanding and a prominent screw head may lead to soft tissue irritation …”

“…Reported failure of intramedullary screw fixation includes delayed union, non-union, and refracture associated with screw failure, especially in basketball, football, and soccer players. 8,10,16,[21][22][23][24] Several screw designs have been used to treat Jones fractures. Currently, neither clinical nor biomechanical studies comparing different screw types offer decisive results, resulting in no consensus concerning the ideal implant or screw diameter.…”