SLR - July 2014 - Jay Seidel

Use of Poly Methyl Methacrylate as Prosthetic Replacement of Destroyed Foot Bones – Case Series

Reference: Varma V, Varma AK, Mangalandan TS, Bal A, Kumar H. Use of Poly Methyl Methacrylate as Prosthetic Replacement of Destroyed Foot Bones – Case Series. The Journal of Diabetic Foot Complications, 2012; Volume 4, Issue 3, No. 3, Pages 71-82.

Reviewed By: Jay Seidel, DPM
Residency Program: Pinnacle Health System, Harrisburg, PA

Podiatric Relevance: A common pathology that is encountered in the podiatric profession is osteomyelitis and Charcot osteoarthropathy manifestations. These two disease processes often result in amputations or removal of integral foot bones, which can cause detrimental sequelae for patients. This article presents a unique option for replacing excised bone and helping to maintain a functional limb.

Methods: PMMA is a powder that hardens with an exothermic reaction when a monomer reagent is added to it, forming a hard substance with a consistency similar to bone. Prophylactic antibiotics may be added when the prosthesis is made. The damaged bone or part of the bone is resected, and the size of the replacement is assessed by measuring the dimensions of the void left after its removal. The PMMA and antibiotic powders are mixed with the reagent and molded into the required dimensions over a titanium screw or K-wire within the setting. A K-wire is passed through the adjacent bones under fluoroscopic control, and is then removed after reaming the bones and the prosthetic screwed in place.

Results: Four (three osteomyelitis and one Charcot) of the six patients in this report are ambulating on molded or modified footwear and have a functionally and cosmetically acceptable foot. One patient who recently underwent surgery is awaiting removal of sutures and is being offloaded. One patient with osteomyelitis did not follow the postoperative instructions and walked on the sixteenth day post surgery which resulted in displacement and exposure of the prosthesis, which had to be removed.

Conclusions: This technique is an effort to salvage the diabetic foot by replacing the damaged bones rather than simply removing them. With good patient compliance the results have been encouraging. The use of implants without antibiotic impregnation puts the already immune-compromised foot at risk for further infection; however, this procedure decreases the risk of infection due to higher local antibiotic concentrations. The major advantage of this procedure is that it provides a more cosmetically and biomechanically stable foot than just resection or amputation alone. 

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