Tumor Prothesis for the Foot

Custom 3D implants have built on momentum with large bone reconstructions to address defects associated with tumor reconstruction in the foot. Currently, there are no tumor prosthesis marketed for the foot.

 

Reconstruction of bone anatomy is hard

 

Reconstructing defects of the foot can be challenging due to the unique anatomy shapes and articulations. Autograft and allograft are less than ideal because of the long operative time to shape the graft, bone the graft resorption, and it can be hard to decipher between tumor recurrence and the bone graft.

 

Outcomes in extremity reconstruction

 

Publishing in Clinical Orthopaedics and Related Research, authors Chandhanayingyong et al. reviewed six tumors of the feet and five tumors of the hand reconstructed with 3D implants with a minimum of two-year follow up. At five years postoperatively, the incidence of implant breakage was 35%. The cumulative incidence of re-operation after the index reconstruction was 29% at five years after surgery. No patient in this series died or experienced local recurrences or metastases. This small but innovative approach showed encouraging results.

​

​

Where There's Smoke, There's Fire?

 

Not always. 

 

In their provocative paper, “The Microbiome of Osteoarthritic Hip and Knee Joints: A Prospective Multicenter Investigation,” Goswami et al. report on the presence of microbial DNA in osteoarthritic knees and hips. In an environment that has been assumed to be sterile, 468 out of 549 samples yielded positive next generation sequencing (NGS) results indicative of microbial DNA.

 

DNA does not equal infection 

 

The presence of microbial DNA in joints, in the absence of other findings of infection, is not diagnostic of infection. This is an important reminder in the era of increasing popularity of molecular diagnosis of periprosthetic joint infections. 

 

Where does this leave us?

 

It is likely that microbial nucleic acids are present in arthritic joints, but it is unclear from where they originated. Next steps will confirm whether the DNA source is from living bacterial colonies within the arthritic joint or if it is transient. There is potential for development in optimizing molecular tests to avoid overreacting to subclinical amounts of bacterial DNA. 

​

Avoiding the Dreaded Amputation

 

Definitive amputation for recalcitrant full thickness surgical wounds is a dreaded complication, defining surgical failure. Over the past decade, orthoplastic reconstruction techniques have continued to gain popularity and acceptance.

 

In their article, "A Retrospective Look at Integrating a Novel Regenerative Medicine Approach in Plastic Limb Reconstruction,” Rodriguez Collazo et al. described a novel technique for limb salvage in patients recommended lower extremity amputation. 

 

The technique

 

• Hemi-soleus and/or peroneus brevis muscle flap 

• Concentrated bone marrow aspirate and platelet rich plasma 

• Dermal wound matrix with wound a VAC-assisted closure for 2-3 weeks

• Split-thickness (0.018) skin graft 

• External fixation for 8 weeks 

 

Outcomes

 

Seventeen patients failed treatment for more than 11 months and were recommended definitive amputation. Four patients had active infection and were on systemic antibiotics. The average defect size was 19.6cm2.  

 

All but one patient successfully achieved limb salvage; definitive amputation was performed for muscle necrosis secondary to compartment syndrome.

​