The Button Temporary Spacer
Definition, History
We were interested in the polyethylene cup described by B. Regnauld in 1975 [98, 99].
This cup provided good results particularly in hallux rigidus surgery. With B. Regnauld we first replace the polyethylene by stainless steel for providing better surrounding soft tissue and increasing the local tolerance. These cups were held by peripheral small holes. Then we de v ised the button prothesis or button spacer [16]. It is thicker than the Regnauld’s cup and it has a central hole allowing the pri- mar y fixation by an axial K-wiring (one
month). This spacer has to be removed from six months to one year postoperative. Later we replaced the stainless steel by Zircone for it provides more mobility and better quality surrounding soft tissue. However the Zircone cup has absolutely to be removed before one year postoperative, since the long-lasting implanting results in abrasion of both the resected phalanx bases and the metatarsal head cartilage. Since there is more abrasion with Zircone than with stainless steel, we now only use stainless steel cup following the recommendations of M. Ragusa.
Fig. 22a1. The temporary button spacer 1. Generalities.
1. From the Regnauld’s cup, made in polyethylene, we first developed a stainless steel cup, with B. Regnauld.
Fixation by peripheral holes.
2. The button is in stainless steel. Fixation by temporary K-wiring.
3. The button in the first MTP joint: Note the preservation of the plantar part of the first phalanx basis, to keep the flexor brevis insertion, as indicated by M. Ragusa (Grenoble, France).
4. Button in lesser MTP joint.
* M. Ragusa, Grenoble, France.
Technique
First ray: MTP joint, respect of the metatarsal head cartilage (osteophytes resection only) and resection of the base of the phalanx trying to preserve a part of the flexor brevis insertion (M. Ragusa).
IP joint: Respect of the basis of the second phalanx and resection of the first phalanx head.
Lesser rays: MTP joint, respect of the pha- lanx base and minimum resection of the meta- tarsal head. Axial K-wiring (1.2mm) to be removed one month after wards.
Results
Secondary displacements of the cup may occur but it is painless and ordinarily without consequences.
However, a long-lasting incorrect position may provide oblique abrasion and secondary deviation of the joint, which indicates an earlier removal of
the cup. The mobility of the joint is good and painless and the radiological aspect of the joint is correct. We used a lot of these spacers from 1985 to 1992, but we progressively stopped because of reliable osteosynthesis in first MTP fusion thanks to the “20” memory staple. Above all we had the possibility of MTP joint preservation on the first ray thanks to the easy first metatarsal shortening with scarf osteotomy on the lesser rays using the Weil metatarsal osteotomy. Both of these osteoto- mies provide such a longitudinal decompression that the MTP joint is opened very far. On the other hand, in the first MTP joint, the resection of the basis of the first phalanx (even when we try to pre- serve the flexor brevis insertion), results in dimini- shing the strength of the great toe ground contact.
For this reason we now reserve the use of this cup for patients who do not want MTP fusion or in case of degenerative change in the corresponding interphalangeal joint. O. Jarde [72] devised a simi- lar cup but with a small insertion in the phalanx base, providing more stability. Its main indication is impaired first MTP joint.
Fig. 22a2. The temporary button spacer 2. Indications and results.
1. A good indication on the great toe: Impaired IP joint combined with necessity of MTP fusion.
2. Long-time implantation results in abrasion of the fragments. The problem is that patients doesn’t feel any discomfort and must be convinced to have the implant removed.
3. Buttons in MTP and IP joints.
4. Indications in lesser MTP joints. For a spondyloarthropathy forefoot, with MTP spontaneous fusion.
The best indication of the button prosthesis is one of the interphalangeal joint of the great toe for arthritic changes or rheumatoid lesion (Fig. 22d). However in very impaired meta-
tarso-phalangeal joints on lesser rays or in spontaneous MTP fusion, as observed in some rheumatoid foot, the use of this button spacer is indicated.
Fig. 22b. The button temporary spacer in hallux limitus.
1. Pre and postoperative MTP range motion with hallux limitus treated by button setting.
2, 6. Hallux limitus: Treatment by button Zircone spacer.
2. Before operation.
3. With K-wiring (one month).
4. MTP joint aspect two years after removing the button.
5, 6. Same case, two years follow-up.
However, the toe ground contact is sometimes decreased (however better than after Keller procedure) and we may observe some remaining discomfort.
Fig. 22c. The button spacer in hallux valgus with MTP impaired joint – Comparative aspects with and without MTP preservation: In the left foot preservation thanks to M1 scarf shortening, in the right foot MTP1 button.
1. Preoperative X-ray and clinical aspect.
2. The right foot with MTP button.
3. One year postoperative aspect (X-ray and clinical aspect when the button is removed). We note that the great toe ground contact is not correct in the right foot (with button).
4. So now we reserve the button spacer for patients who do not want to have a MTP fusion or when the IP joint is too much impaired. For other cases, MTP fusion is indicated.
Fig. 22d. The button spacer in first IP joint.
In impaired or stiff first IP joint, the button spacer gives good results, avoiding in most cases to perform IP fusion. In this plate one case of rheumatoid forefoot before surgery and one year after removing the button.
When the first IP joint is only stiff, we always peform a plantar soft tissue release, which is sufficient in most cases.
Fig. 22e. Button spacer in lesser MTP joints.
It is rarely indicated. But here are two cases of good indications:
1. In iatrogenic forefoot severe disorder.
2. In rheumatoid forefoot with spontaneous lesser MTP joint fusion.
