Title: Safe Zone for the Placement of Medial Malleolar Screws
Authors: John E. Femino, MD, Brian F. Gruber, MD and Madhav A. Karunakar, MD
Source: The Journal of Bone & Joint Surgery (American). 2007; 89:133-138.
PODIATRIC RELEVANCE:
Hardware placement for fracture fixation can often be a difficult and challenging procedure. The prominence of hardware is a frequent cause of pain status post open reduction internal fixation of ankle fractures. This study was intended to assess the risk of injury to the posterior tibial tendon with the placement of screws into specific areas of the medial malleolus.
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 in this study. The Authors used 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 did not contact the posterior tibial tendon. Screws placed in zone 2 were about 2 mm from the posterior tibial tendon but did not cause injury but were found to be in contact with the posterior tibial tendon in 4 out 10 specimens. Screws placed in zone 3 at the level of the posterior colliculus all resulted in tendon abutment in all ten specimens and in tendon injury in five of the ten specimens.
COMMENTS:
Screws inserted posterior to the anterior colliculus in fracture fixation can place vital soft tissue structures at risk for injury which include the posterior tibial tendon. One must be careful when inserting fixation so that they can avoid damaging or potentially causing unnecessary pain to the patient at a later date. When fixating medial malleolar fractures, one should try to place the screws at the anterior colliculus or safe zone.
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Disclaimer:
Scientific Abstract Monthly postings are submitted by podiatric surgical residents. The ideas presented are not the opinions of the American College of Foot and Ankle Surgeons (ACFAS), nor are they presented as facts. ACFAS presents this information without any warranty of any kind, expressed or implied, and is not liable for its accuracy nor for any loss or damage caused by the user's reliance on information obtained in these areas.