The Journal of Bone and Joint Surgery (American). 2007;89:133-138.
doi:10.2106/JBJS.F.00689
© 2007 The Journal of Bone and Joint Surgery, Inc.
Safe Zone for the Placement of Medial Malleolar Screws
John E. Femino, MD1,
Brian F. Gruber, MD2 and
Madhav A. Karunakar, MD2
1 Department of Orthopaedic Surgery, University of Iowa, 200 Hawkins Drive,
01016 JPP, Iowa City, IA 52242-1088
2 Department of Orthopaedic Surgery, University of Michigan, 1500 East Medical
Center Drive, Taubman Center 2914, Ann Arbor, MI 48109-0328. E-mail address
for M.A. Karunakar:
mkarun{at}umich.edu
Investigation performed at the Department of Orthopaedic Surgery,
University of Michigan, Ann Arbor, Michigan
Disclosure: The authors did not receive grants or outside funding in
support of their research for or preparation of this manuscript. They did not
receive payments or other benefits or a commitment or agreement to provide
such benefits from a commercial entity. No commercial entity paid or directed,
or agreed to pay or direct, any benefits to any research fund, foundation,
educational institution, or other charitable or nonprofit organization with
which the authors are affiliated or associated.
Background: Hardware placement for fracture fixation can put
soft-tissue structures at risk for injury or abutment. The prominence of the
hardware is a frequent cause of pain after the fixation of ankle fractures.
This study was designed to assess the risk of injury or abutment of the
posterior tibial tendon with the placement of medial malleolar screws.
Methods: Ten unmatched cadaveric limbs that had been disarticulated
at the knee were used, and the medial malleolus was exposed by dissection of
the skin. With use of fluoroscopy and direct visualization of the deep fascia,
three Kirschner wires were placed through the tip of the medial malleolus and
directed parallel to the medial articular surface. The first wire was placed
in the center of the anterior colliculus. Two additional wires were placed
parallel and posterior to the initial wire at 5-mm intervals. The wires were
overdrilled, and 4.0-mm screws were inserted over the Kirschner wires. The
specimens were dissected to inspect for trauma and the proximity of the screws
to the posterior tibial tendon. The medial malleolus was divided into three
zones on the basis of anatomic landmarks. Zone 1 is the anterior colliculus;
Zone 2, the intercollicular groove; and Zone 3, the posterior colliculus.
Results: Screws placed in Zone 1 (the anterior colliculus) did not
contact the posterior tibial tendon in any specimens. Screws placed in Zone 2
(the intercollicular groove) were, on the average, 2 mm from the posterior
tibial tendon. Screws placed in Zone 3 (the posterior colliculus) resulted in
tendon abutment in all ten specimens and in tendon injury in five of the ten
specimens.
Conclusions: Screws inserted posterior to the anterior colliculus
place the posterior tibial tendon at significant risk for injury or
abutment.
Clinical Relevance: On the basis of these results, we recommend
direct visualization of the posterior tibial tendon prior to the placement of
screws in the medial malleolus when they are inserted posterior to the
anterior colliculus.

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