When A Vitamin D Deficiency Complicates Bunion Surgery
- Volume 25 - Issue 7 - July 2012
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My typical fixation for this type of procedure is a combination of lag and anchor screws at the base wedge osteotomy (using metal screws) and bioabsorbable fixation of a Reverdin-Green-Laird osteotomy of the metatarsal head (if necessary). The preoperative workup for this patient included a complete blood count with differential, basic metabolic panel and pregnancy testing.
At the time of surgery, I employed a standard longitudinal incision at the dorsomedial aspect of the first ray. In performing double osteotomies of the first metatarsal, take care not to interrupt the nutrient artery at the proximal medial shaft. One should also avoid denuding or aggressively dissecting the periosteum as this is a known reason for osteotomy failure. I placed an axis guide into the proximal medial cortex of the first metatarsal to prevent dorsal displacement, another known complication of this type of osteotomy. I also used care when placing the osteotomy guide inside of the medial cortical wall in order to prevent hinge breakage.
When One Encounters Poor Bone Quality Intraoperatively
When performing the osteotomy, I realized the bone had some areas that were softer than anticipated. Any surgeon who has worked on young individuals has experienced the usual good bone quality and pliability of osteotomy hinges. Personally, I have even foregone the anchor screw in healthy younger women when the hinge was strong and the lag screw reduced the osteotomy sufficiently.
As I removed the axis guide and wedge, I closed the base wedge osteotomy site with bone reduction forceps. However, to my dismay, I heard a snapping sound akin to peanut brittle breaking. In my experience, this is not uncommon in middle-aged to older individuals but I had never experienced this with such a young female patient. Breaking the hinge of a closing base wedge osteotomy certainly has its own challenges in fixation. However, as I tried to place the anchor and lag screws, I found additional areas of poor bone quality, necessitating three points of fixation. If a locking plate had been available, this would have been a better choice for fixation.
Immediately in the recovery room, I requested a 25(OH) vitamin D level testing. This indeed confirmed my suspicion of vitamin D deficiency. She started on a regimen of vitamin D 50,000 IU/week. Her postoperative course was prolonged due to fear of metatarsal/osteotomy fracture in the case of an early return to weightbearing. I deferred her weightbearing until she was between weeks six and eight postoperatively. While her bone was improved at that time, there had also been a delay for range of motion as well. This caused difficulties including pain and altered gait in the third and fourth postoperative months.
What You Should Know About Vitamin D Deficiency
Vitamin D insufficiency is defined as 25(OH) vitamin D levels less than 30 ng/mL, and vitamin D deficiency occurs when levels are <20 ng/mL. In this case, the level immediately after the procedure was approximately 19 ng/mL, which is in the range of deficiency according to the most recent definition.6 Algorithms exist to help guide vitamin D replacement and supplementation as well as monitoring of levels in the affected patient.7 One should exercise caution with Vitamin D replacement so as not to cause hypervitaminosis D. The oil soluble vitamins (A, D, E and K) all have a risk of excess accumulation/toxicity.
Subsequent monitoring of patients under treatment should occur between two and three months after initiating therapy. Of course, one should notify the patient’s primary care physician of the findings and he or she should be allowed to manage the replacement (and subsequent long-term maintenance) if desired.