An Emerging Option For Treating Severely Subluxed Lesser MPJ Deformities In Seniors

The correction of a significantly subluxed or dislocated hammertoe in an elderly patient can be a challenge to any surgeon. Over the last 22 years, I have tried numerous ways to correct the problem, all with varying degrees of success. The use of the Weil osteotomy along with other procedures, including proximal interphalangeal joint fusion, flexor transfer and now plantar plate repair from a dorsal approach, has not given me consistent results with patients who are over 65 years of age.

   I also have found plantar plate repairs to be of limited value in the severely dislocated lesser MPJ, especially in dislocations that have been present for more than just a few months. In my experience, many times the plantar plate is in poor condition and it is difficult to achieve primary repair. However, this procedure is an excellent choice if bone quality is an issue in cases in which rigid fixation may be problematic and also works well in multiplanar deformities.

   In 2007, Vanore discussed using absorbable pin fixation along with base resection of the proximal phalanx and proximal interphalangeal joint fusion to correct the most significant MPJ subluxations and dislocations.1 I know what you are thinking about going back in time with base resections but in doing these procedures with absorbable fixation, as described by Vanore, in the right patient population, I have found the results are more consistent and the reduction of the deformity is better in the short- and long-term in comparison to the other aforementioned techniques.

   Kelikian was one of the first surgeons to address the MPJ deformity with resection of the proximal phalanx base. The long-term results and complications, especially shortening of the toe and flail toe, occurred so often that he advocated for syndactyly at the same time to allow for more stabilization.2,3 However, when you look at old X-ray images of these procedures or every now and then have a patient who had one done years ago, you will see that resection of the base of the phalanx is typically well distal to the metaphyseal flare of the base of the proximal phalanx. This excessive resection, along with any procedure that was also done at the proximal interphalangeal joint, is what will typically lead to a short, flail toe.

   I believe the key to the success of this procedure, as with all procedures, is patient selection. My criteria for patient selection are based on several factors including age, severity of the deformity and the length of the time the deformity has been present. My typical patient is someone who is usually over 65 and has a significantly subluxed, usually dislocated lesser MPJ that has been present for more than three months. Some of these patients may also have a hallux valgus deformity. I also have found this procedure to be a good choice in patients with significant MPJ degeneration, with or without digital subluxation, as well as patients who have had previous surgery on the joint that requires revision.

Step-By-Step Insights On The Procedure

The technical aspect of the procedure is relatively straightforward. I use a dorsal curvilinear incision starting at the dorsal MPJ and extending distally to just past the proximal interphalangeal joint. I perform a transverse tenotomy of the extensor tendon at the dorsal proximal interphalangeal joint and detach the tendon along its medial aspect, and reflect it back to the dorsal MPJ to expose the dorsal joint capsule. If the tendon needs lengthening, I typically do z-lengthening instead of a transverse resection.

   I proceed to perform a dorsal transverse capsulotomy to expose the base of the proximal phalanx, which is typically dorsally dislocated on top of the metatarsal neck. One would then dissect the base of the proximal phalanx free from any soft tissue attachments to prepare for resection. Use a sagittal saw to remove the base of the phalanx from medial to lateral, dorsal to plantar, just proximal to the metaphyseal flare of the phalanx. I usually resect no more than 3 to 4 mm of bone. I can always resect more later if necessary but I never resect so much of the base that I can no longer see the flare at the base. Once I have completed the bone cut, I remove the cut portion of the base. At this point, you will now see the metatarsal head and that the toe is much more easily relocated into a more normal anatomic position.

   I subsequently use a McGlamry elevator to free up the rest of the inferior surface of the joint and any other medial or lateral adhesions. I then prepare the proximal interphalangeal joint for fusion. I only resect the articular surfaces off the head of the proximal phalanx and base of the middle phalanx. I use a Trim-It® 1.5 mm pin (Arthrex) or a 1.3 mm OrthoSorb® Pin (Biomet) to fixate. The Trim-It pin is slightly longer and a little more rigid than the OrthoSorb pin. This is a factor depending on the size.

   I use the guide wire that comes with the pin kit to find the medullary canal by hand at the proximal phalanx and drive it in until I can see it exiting the base. Remove the wire and drill distally into the middle phalanx, across the distal interphalangeal joint and out the distal toe. (If you are using the OrthoSorb pin, you will not be able to cross both joints with one absorbable pin because of the length and will need to use two absorbable pins.) Now drive the guide wire across the proximal interphalangeal joint fusion site from distal to proximal through the previous hole you made so you can see the tip of the K-wire coming out the base of the phalanx.

   With the MPJ reduced to a slightly plantarflexed position, drill the wire into the metatarsal head to a depth of about 2.0 to 2.5 cm. Try to make sure the hole is slightly angled going into the metatarsal head because you do not want to go straight down the shaft into the medullary canal. Angling the drill hole allows control over how far the absorbable pin can go into the metatarsal and prevents proximal migration.

   Once you are satisfied with the position, remove the wire and insert the absorbable fixation. With the Trim-It pin, you can retrograde it out the distal toe and then drive the pin from the distal toe, crossing the distal interphalangeal and proximal interphalangeal joints. Drive the absorbable pin so you can see it exiting the base of the phalanx, align it with the hole you already drilled in the metatarsal head and drive the pin into the metatarsal about 2 to 2.5 cm. Once the pin is across the MPJ, cut the pin flush with the tip of the toe and tamp the distal end so it is under the skin. The OrthoSorb pin is not long enough or rigid enough to do it this way. You must insert the OrthoSorb down the proximal phalanx and across the MPJ, leaving about 5 mm exposed at the proximal interphalangeal joint fusion site to place the middle phalanx over. You can also do this with the Trim-It pin if you do not want to cross the distal interphalangeal joint. Closure is normal from here and is the surgeon’s preference.

Final Notes

Postoperatively, the patient can weight bear immediately in a rigid post-op shoe or controlled ankle motion (CAM) walker. I prefer the CAM walker that also limits ankle motion. It is important to limit any potential motion at the MPJ joint while the surgical site begins to fibrose so the pin does not weaken and break. Depending on any other procedures you utilize, these patients are typically returning to an athletic style shoe at five weeks with use of a removable digital sling to keep the toe plantarflexed for the remaining healing process. One can control swelling with ½ inch Coflex or any other self-adherent wrap for compression as necessary.

   Overall, I have found this base resection with absorbable fixation and proximal interphalangeal joint fusion to be a very good and predictable procedure for the significantly subluxed or dislocated lesser MPJ. The procedure is not technically difficult yet is very effective at reducing significant subluxations and dislocations of the lesser MPJs.

   Dr. Tritto is board-certified in foot surgery by the American Board of Podiatric Surgery. He is in private practice in Rockville, Md.

References
1. Vanore JV. Use of absorbable pin stabilization of the lesser metatarsophalangeal joints. The Podiatry Institute Update 2007: Proceedings of the Annual Meeting of the Podiatry Institute, Ch. 3, The Podiatry Institute, Inc. Tucker, Ga., 2007, pp. 11-18.
2. Kelikian H. Deformities of the lesser toes. In: Kelikian H (ed): Hallux Valgus, Allied Deformities Of The Forefoot And Metatarsalgia. WB Saunders, Philadelphia, 1965, pp. 282-336.
3. Kelikian H, Clayton L, Loseff H. Surgical syndactylia of the toes. Clin Orthop 1961;19:208-231.