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Study Assesses Revision Procedures For Total Ankle Replacement

In a recent retrospective study examining revision cases of total ankle replacement (TAR), researchers noted a 79 percent success rate with primary revision and an average four-year survivorship of the revision implant.

The study, which was presented as a poster abstract at the recent Annual Scientific Conference of the American College of Foot and Ankle Surgeons (ACFAS), assessed consecutive patients who had a revision TAR over a 11-year period from 2005 to 2016 with the same surgeon, Jack Schuberth, DPM. Ninety-three patients were included in the study with an average patient age of 61.6 years at the time of primary revision.

David R. Collman, DPM, FACFAS, a co-author of the study, says successful TAR revision depends on multiple factors.

“Successful revision TAR is dependent upon surgeon experience and skill, including decision-making about when to revise the failed TAR; realistic patient expectations; adequate bone substrate to support the prosthesis; balancing the ankle and correcting foot deformity; restoration of the joint axis; and technique flexibility (e.g., employing custom methods when specialized prostheses are not available),” explains Dr. Collman, the Assistant Chief of Foot and Ankle Surgery in the Department of Orthopedics at Kaiser Permanente in San Francisco.

Ryan L. McMillen, DPM, FACFAS, praises the work of Dr. Collman and his colleagues in the study.

“This (study) gives other podiatrists who perform TAR invaluable information when discussing revision procedures with their patients,” notes Dr. McMillen, a member of the faculty of the Western Pennsylvania Hospital Foot and Ankle Residency Program in Pittsburgh.

In his own experience with TAR, Dr. McMillen says he has seen good results with revision TAR “as long as there is appropriate bone stock on both the tibia and talus that is conducive to fit the implant.” He says other factors for successful TAR revision include minimal residual deformity, patient adherence and appropriate workup for infection.

The study also involved implants from multiple manufacturers. Researchers noted seven primary TAR implants and six implants used for the revision procedures.

“Primary semi-constrained TAR systems may be utilized if the native bone substrate is well preserved overall and cysts can be filled, but these opportunities are infrequent and the mode of failure may be similar,” points out Dr. Collman.

“In cases of distal tibial bone loss, we favor a stemmed implant because it permits load sharing, although in some cases, this prosthesis makes alignment more challenging and explantation is difficult (though rarely necessary). The ideal revision talar prosthesis utilizes flat cuts that are necessary in most cases because of talar bone loss where talar resurfacing is not possible. However, advanced methods such as the cement and rebar technique may be necessary for massive talar defects.”

The study mentions osteolysis and aseptic loosening as key causes of TAR revision failure. In order to reduce the risk of these complications, Dr. McMillen advises the use of bone graft and bone graft substitute, appropriate use of bone cement, and attention to detail on implant positioning. Dr. Collman says balancing the prosthesis is “critical.”

“In our series, 45 percent of the revision failures were due to frontal plane instability,” emphasizes Dr. Collman. “This is a difficult problem.”

Dr. Collman says surgeons should build up the prosthesis from the talus to or down from the tibia to correct for bone loss and reestablish the joint axis. While he notes this is not proven, Dr. Collman says this concept makes sense intuitively. He also points out that the selection of thicker polyethylene helps balance the ankle and potentially improves device longevity.

“Patients are (also) educated about limiting excessive pedal load, uneven ground and other activities that may place significant stress on the prosthesis and the surrounding bone,” adds Dr. Collman.

What A New Study Reveals About Biplanar Plating For First Ray Arthrodesis Procedures

By Jeff A. Hall, Executive Editor

Assessing the use of biplanar plating without compression for first ray arthrodesis, the authors of a new study noted a 97 percent success rate for bone healing in 195 first ray arthrodesis procedures at an average 9.5-month follow-up.

According to the study, which is in press with the Journal of Foot and Ankle Surgery, the authors reviewed results from 85 first MPJ arthrodesis procedures and 110 first tarsometatarsal arthrodesis procedures. At the final radiographic follow-up, the authors reported that 98.2 percent of the first MPJ arthrodesis cases and 96.8 percent of the first tarsometatarsal fusion cases demonstrated stable bone segments, osseous bone filling and intact hardware without loosening.

“These are impressive results that are far better than other published data on non-union rates for the first tarsometatarsal or first MPJ fusions,” notes William Fishco, DPM, FACFAS, who is board-certified in foot surgery and reconstructive rearfoot and ankle surgery by the American Board of Foot and Ankle Surgery.

When it comes to internal fixation for arthrodesis procedures, Dr. Fishco says there has been a certain dogma in podiatry about getting as much compression as you can.

“The reality is that no one really knows how much compression is really necessary and at what point, is there too much compression that could undermine bone healing,” notes Dr. Fishco, a faculty member of the Podiatry Institute. “In my mind, stability is more important than compression. … Orthogonal or biplanar plating addresses the ultimate in stability, and that is why it works.”

Dr. Fishco employs this fixation approach for bone grafting procedures and revision cases. While he concedes that biplanar plating is not his primary approach to internal fixation for fusions at this time, Dr. Fishco says “it is certainly something that we as a profession should look at.”  

In regard to Lapidus procedures, H. John Visser, DPM, FACFAS, performs biplanar plating with lag screw compression. He notes that he orients the locking plate in a plantar medial manner in order to provide some compression on the tension side with early weightbearing. With lag screw compression, Dr. Visser, the Director of the SSM Health DePaul Hospital Foot and Ankle Surgery Residency in St. Louis, allows immediate partial weightbearing for two weeks and then full weightbearing for the next four weeks.

The study authors note that they allowed early weightbearing in a post-op boot approximately five days after surgery. While Dr. Fishco thinks this is okay for first MPJ arthrodesis procedures, he is a little hesitant to start immediate weightbearing after a first tarsometatarsal fusion. Dr. Fishco says this is patient dependent. While a patient weighing between 200 to 300 pounds may not be the best candidate for early weightbearing, Dr. Fishco says early partial weightbearing with crutches is reasonable for healthy, fit individuals.

Overall, for the most part, Dr. Fishco says critical joint preparation and internal fixation that provides stability are vital to achieving fusion. Dr. Visser concurs, noting that “tedious preparation of the joint”—curettage, fenestration and fish scaling of the joint—has been the key for his Lapidus procedures.

Assessing Dorsal Plating Techniques For First MPJ Arthrodesis

By Jeff A. Hall, Executive Editor

Do variations with dorsal plating techniques facilitate different outcomes with first metatarsophalangeal joint (MPJ) arthrodesis?

A recent study involving 274 first MPJ fusion procedures compared dorsal plating with a positional screw versus dorsal plating with a compression screw. The study, which was presented as a poster abstract at the aforementioned ACFAS conference, found no statistically significant differences between the two fixation groups.

There were reportedly no complications with 77 percent of the procedures.

“I have found that dorsal plating provides more stability and higher union rates than other forms of fixation for first MPJ arthrodesis,” notes Patrick DeHeer, DPM, FACFAS, a member of the Board of Trustees of the American Podiatric Medical Association (APMA).

In regard to the different approaches with dorsal plating in the study. Jason St. John, DPM, a co-author of the study, says it comes down to surgeon preference but notes there are other considerations in those with larger deformities or poor bone stock.

“In those with very large deformities, it may be beneficial to place a screw first to help aid reduction although temporary K-wires may have the same benefit,” suggests Dr. St. John, a fellow in lower extremity limb salvage and trauma at the University of Pittsburgh Medical Center. “Likewise in patients with poor bone stock, placing a screw first may also be useful as it would eliminate the need for temporary K-wire usage and eliminate some damage to the bone.”

Dr. DeHeer says his preference of fixation for first MPJ arthrodesis is a combination of dorsal plates with a compression slot along with temporary pin fixation and an external compression clamp.

“Maximum compression using an external fixation source, adding additional compression through the compression slot and finally locking the construct with multiple fixed right angles provide a robust method of fixation,” explains Dr. DeHeer, the Podiatric Residency Director at St. Vincent Hospital in Indianapolis.

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