168 Forefoot Reconstruction
Use of the “20” Memory Staple in Osteotomies of Fusions of the Forefoot
Definition, History, Generalities
This staple first provides a permanent compres- sion both in the prongs extremities and in the oval part which units the two prongs.
During the last fifteen years, we have used a memory staple in one indication: The shaft osteotomy of the great toe first phalanx. It is the memory staple “12” – i.e. 12 mm distance bet- ween the two prongs – but it was neither strong enough nor large enough to have indications other than the great toe P1 osteotomy. So, we devised a stronger and larger staple (20 mm) for the other indications in foot surgery, i.e.: fusion of the first MTP joint, of the Lisfranc’s joint, osteotomies of the metatarsals, and osteotomy or fusion of the hindfoot.
Once osteotomy has been made, or the resec- tion for fusion has been carried out, temporary fixation is performed. Then the guide deter- mines the position of the two drills, then the length of the prongs is measured. Finally the staple is easily introduced. One or two staple are used following the indication.
Indications and Results
Basal Metatarsal Osteotomies (Fig. 21a)
Principally it is the first metatarsal osteotomy, notably the elevation osteotomy, or the varisa- tion osteotomy. For the other metatarsals, we use only the “20” memory staple in case of non union after any osteotomy.
Fig. 21a. Basal osteotomies of the first metatarsal.
1. Variation osteotomy for correction of introgenic hallux varus (see Fig. 14c3).
2. Elevation osteotomy for correction of over pressure under the first metatarsal osteotomy or for pes cavus.
3. Treatment of a non union of metatarsal osteotomy.
Fig. 21b1. The “20” memory staple in the 1st MTP fusion: 1. Technique.
1. The principles of the “20” memory staple are the same than the “12” inter axis staple, i.e. bilateral compression – both on the oval part and on the prongs extremities – and permanent elasticity but the inter axis is up to 20 mm and is adapted with strong ness.
2. Removal of the cartilage to reach the subchondral bone, avoiding to reach the cancellous bone.
3. Pride perforation if required.
4, 5. Temporary double K-wiring and checking of the correct great toe position in both horizontal and sagittal planes. Our rule: Not too much MTP dorsal flexion, (i.e. 2 cm between the heel and the board) and a slight MTP valgus, assessed by the Load Simulation Test.
6, 7. The two staples are set.
6. The first staple in a transverse plane, through the medial cortex.
7. The second one in a sagittal plane, through the dorsal cortex, is set slightly proximally comparatively to the transverse staple.
Fig. 21b2. The “20” memory staple in the first MTP1 fusion. Advantages.
1, 2. Very small resection of the fragment extremities allowing to keep as far as possible the great toe length.
3. Permanent compression allowing good healing in spite of inter fragmental resorption.
4, 5, 6. In case of non-union of previous fusion attempt, good results with only removal of the osteosynthesis implants and setting of the memory staple.
170 Forefoot Reconstruction
Fig. 21b3. The “20” memory staple in the first MTP1 fusion. Drawbacks.
1. The sagittal proximal prongs are too long.
Incorrect position of the fragments.
2. Too much dorsal flexion: Keratosis in dorsal IP part. It is difficult to repair (plantar flexion osteotomy).
3. Too much plantar flexion (and incorrect toe rotation).
4. Repairing is easier with an oblique dorsal distal closing wedge. Fixation with the “20” memory staple.
First Metatarso Phalangeal Joint Fusion
Two staples are used in perpendicular planes.
With this staple, the fusion is remarkably easy and reliable. Very few cases of non union were observed, and in four cases of non union after any fixation, the fusion was obtained without bone grafting, with only removing the previous fixation and using two “20” memory staples.
Lisfranc’s Fusion
We know the difficulty to obtain fusion in this location with traditional fixation. On the contrary in this indication, the permanent com- pression of the memory staple is very useful, providing a reliable fusion in all cases.
Fig. 21b4. First MTP fusion with “20” memory staple. Indications.
1. Hallux limitus.
2, 3, 4. Extremely impaired MTP joint.
2. With hallux valgus.
3, 4. Rheumatoid forefoot (note the possibility of preserving one side with M1 scarf shortening).
5, 6. Severe hallux valgus overcorrection.
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Fig. 21c1. Lisfranc’s fusion. Problems occurring with usual fixation.
1, 2. Fusion is sometimes difficult in the first ray even when using two screws.
3. Fusion is also difficult in the second and third cuneo-metatarsal joints.
Fig. 21c2.Lisfranc’s fusion with the “20” memory staple.“ 1, 2. Fusion in posttraumatic first cuneo-metatarsal joint.
3.4. Isolated fusion in second cuneo-metatarsal joint.
5.6. With these staples, there is no need of postoperative cast but only the use of heel support shoe for six weeks.
7.8. Fusion for Lapidus procedure (indication: hallux valgus with arthritic cuneo-metatarsal joints).
Fig. 21c3. Combination of first cuneo-metatarsal fusion and Weil lesser metatarsals osteotomy.
To balance the shortening of the lesser rays, the first MTP fusion is not enough. So we perform the first phalanx great toe shortening.
