Hallux rigidus or osteoarthritis of the first MPJ is a very common problem we see as foot and ankle surgeons. The issue is caused by repetitive microtrauma or an acute traumatic event, which contributes to an arthritic process in the great toe joint. Commonly, I see patients who have moderate to significant cartilage damage. When patients have early stage arthritis, one may employ conservative care options such as shoe modification, prefabricated insoles, orthotics and injection therapy.
Should the osteoarthritis in the first MPJ progress, surgical intervention is commonly the best solution. Surgical options range from spur removal to fusion of the great toe joint. Commonly, when patients have mid-level cartilage damage, surgeons can consider joint salvage options. Salvage options include osteotomy to realign the joint with spur removal or implant placement with spur removal.
One of the latest implants to hit the foot and ankle market is a polyvinyl synthetic implant (Cartiva®, Wright Medical Group). The use of this cartilage replacement device has been touted as a simple procedure, which enables surgeons to replace the damaged cartilage with a bullet-sized implant they can place into a intraoperatively created pilot hole in the first metatarsal head. The surgeon press fits the implant into the pilot hole, leaving the distal tip proud to act as a spacer in the damaged great toe joint. In my experience with the Cartiva implant, the procedure is very simple and fairly reproducible.
The initial studies presented for FDA approval of the product show impressive results and the procedure has become very popular. However, being with one of the initial groups that placed the Cartiva implant in patients, we have found that the procedure has a significant failure rate, requiring revisional surgery. Currently, we no longer use the Cartiva implant as a treatment option for first MPJ arthritis as we have found an over 50 percent failure rate in our cases.
In my practice, our team has seen and treated a large number of patients with failed Cartiva implant procedures, originating both internally and from referring doctors. Most patients in question state they had a very short period of relief, if any at all. Some patients state the pain never truly went away and they do not quite understand what went wrong. This has been a common complaint among doctors as well. We do not quite understand why the procedure did not work or seems to fail when the initial implant placement seems perfect, and there has been no intraoperative trauma.
A Few Thoughts On Possible Etiologies For Implant Failure
Our initial consideration was a possible bone density issue with soft bone resulting in subsidence of the implant. However, this does not seem to be the case because a hard shell of bone is evident in the drilled region after removal of the implant. A second consideration is implant damage, which has also not been proven as removed implants sent to the manufacturer show no damage at the time of removal.
A final thought is shrinkage of the implant upon placement. In this hypothesis, the implant is thought to shrink due to lack of hydration. The Cartiva implant is mainly water-based. Prior to placement in the foot, it is soaked and held in a water medium to keep it hydrated. Once one has put in the implant, it is thought that there may be a lack of hydration due to the degree of arthritis in the joint. Another possibility is a lack of joint fluid in an incised joint, resulting in the implant “getting dry” and shrinking. This could then allow the implant to sink into the hole made in the bone, resulting in a lack of joint space and concurrent joint pain. Although these hypotheses are worth consideration, the actual cause of significant numbers of procedure failure is not clear.
Pertinent Insights On Revision Procedures
So what are the best options for revision surgery for a failed Cartiva implant procedure?
We have spent an extensive amount of time evaluating options for treatment of a failed implant and currently consider three options; two of which we have performed and one that we are considering performing. These three procedures are: fusion of the great toe joint; replacement of the Cartiva implant with another implant; and revision of the Cartiva implant with a bone substitute material at the base of the implant. At our practice, we have performed successful fusion and revisional implant placement. We are still investigating the possibility of revision of the Cartiva implant with a bone cement placement at the base of the implant to give the implant a strong maintenance floor but have not yet attempted this procedure.
First MPJ fusion. Fusion of the great toe joint due to a failed Cartiva implant procedure is, in our experience, quite simple, reproducible and successful. One can easily remove the implant and clean out the depth of the implant void with debridement of any synovium or tissue buildup. The surgeon then fills the bone void with a bone graft substitute or bone graft material, either allogeneic or autogenic.
If you use autogenous bone graft, a quick and easy technique is to harvest bone graft from the heel with the use of a bone trephine. One can harvest the bone from the posterior plantar heel, similar in style to the placement of a retrograde calcaneal screw, or from the lateral posterior heel wall. The surgeons can then use bone graft to fill the first metatarsal head void.
If you employ allogeneic bone, my preferred method is the use of cancellous bone chips soaked in a bone marrow aspirate concentrate that I subsequently place in the first metatarsal head void. One may take the bone aspirate from the lateral heel or anterior tibia, and then convert it into aspirate concentrate with one of many available stem cell concentrate systems. Surgeons then combine this bone concentrate with allogeneic bone and pack it into the first metatarsal bone void region. I also suggest using a similar stem cell concentrate if you are utilizing a bone graft substitute to increase healing potential in the region.
When it comes to fixation of the fusion, I prefer a plate technique. Due to the metatarsal void, crossed screw fixation is not as strong. In my experience with these cases, I have found that a dorsal plate is stronger and allows earlier weightbearing potential. My current preferred plate system is the Dynaforce Fusion System (CrossRoads Extremity Systems). This fixation system is a combination of a plate and internal screw/plate/staple, which allows for stable screw and plate fixation with compression through the nitinol material in the staple. However, surgeons may also utilize a pure screw-fixated plate.
Since the bone graft is within the drill hole and has a cortical bone rim, compression is not an issue. One also needs to prepare the surrounding bone rim for fusion as it may have cartilage and cortical bone present at the cap. We have found fusion to be the most reproducible revision procedure with very few complications other than the potential need for plate removal.
An essential consideration is the angle of toe placement. A plate at zero degrees is best for men and women who do not wear high heels, and prefer significant grasping strength of the toe. Competitive athletes would favor this angle of toe placement.One may utilize a five or ten degree plate for patients who require some elevated position of the toe in order to have greater shoe and higher heel options.
Implant revision. A second option for a failed Cartiva procedure is a revisional implant. In such cases, the patient has a significant requirement for shoe gear such as high heels and a fusion is not a good option. It is important to educate the patient as to fusion versus implant pros and cons as many patients will feel comfortable with a fusion, and not want to take on the risk of another implant surgery. However, in a case requiring range of motion of the great toe, we have found the HemiCAP DF® (Arthrosurface) implant to be the best option. This implant allows rapid recovery and return to shoes in one to two weeks. It is fairly simple to swap implants and the overall results are excellent.
There are a few pearls and pitfalls to consider. It is important to know if the patient’s original implant is eight mm or 10 mm. If the implant is eight mm, one may employ the typical HemiCAP DF implant stem. This stem is also eight mm and is easy to fit in the same hole. Arthrosurface has designed a new 10 mm stem for 10 mm implant failures. It is important to make sure this implant is present when it is needed.
In either case, a bone graft substitute with some hardening is helpful for revision surgeries when the bone is soft or requires some surrounding void filler with the new stem placement. It is important that the filler be somewhat structural and not just a soft filler. These bone graft substitutes are available through multiple companies.
After placement of the stem, one press fits the cap on the stem and covers the metatarsal head, including the dorsal surface. We prefer the HemiCAP DF implant as a replacement because the implant is very strong and relies on a Morse taper construct of stem-to-cap which allows placement in more types of previous surgically treated bone. Furthermore, if the joint is very tight and narrow at the time of revision, one can shorten the metatarsal somewhat with the HemiCAP DF implant. This may create some joint space and improve motion.
Finally, should a proximal phalanx implant also be necessary in severe arthritis cases, one may utilize the HemiCAP DF implant with a complete bilateral replacement of the phalanx and metatarsal. However we have not found this to be necessary to date.
In conclusion, we have not found the Cartiva implant to be an ideal option for hallux rigidus intervention and have stopped utilizing the implant. We have found that the outcomes presented in initial trials of Cartiva are significantly better than our findings and those of our colleagues. Additionally, in my practice, we have seen a large number of referrals for revision of failed Cartiva implant procedures and approximately 50 percent of our own patients have had a failed Cartiva implant procedure unrelated to complications at the time of surgery. We have found first MPJ fusion to be the best long-term option for revision of such failures but the HemiCAP DF implant has also shown significant promise in our patients requiring motion in the great toe joint.
Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is the Director and Fellowship Director at the University Foot and Ankle Institute in Los Angeles (https://www.footankleinstitute.com/podiatrist/dr-bob-baravarian ).