Transverse Z-Osteotomy: Is It A Viable Adjunctive Option For Hallux Limitus?
In addition to all the advantages of other classic hallux osteotomies over the Regnauld procedure, the transverse Z-osteotomy, by design, provides complete anatomical protection of the sesamoidal apparatus attachments in the plantar base of the proximal phalanx. This may or may not contribute to good mobility of the sesamoidal apparatus. Also, this procedure includes the ability to correct for transverse plane deformities of the hallux or a pathologic hallux abductus interphalangeus.17-22
A Step-By-Step Guide To The Procedure
The surgeon makes a skin incision, usually as a distal extension of the bunionectomy incision, over the medial aspect of the proximal phalanx. One would deepen the incision through the subcutaneous tissues to the level of the periosteum. Dissection exposes the medial head, shaft and the medial base of the proximal phalanx. Surgeons would proceed to insert two 0.045-inch smooth Kirschner wires in a parallel manner in the transverse plane, perpendicular to the long axis of the proximal phalanx, and into the center of the base and the head of the proximal phalanx.
Using an oscillating saw, one can perform the first osteotomy transversely between and in the same plane with the Kirschner wires through the medial and lateral cortices. Place the second osteotomy in the frontal plane at the distal Kirschner wire plantar to the K-wire. Surgeons can place the third osteotomy parallel and proximal to the second. One would place the fourth osteotomy distal to the proximal Kirschner wire and equal to the distance between the second and third osteotomies. This fourth osteotomy is parallel to the proximal Kirschner wire and through the dorsal aspect of the bone. The fifth osteotomy is at the site of and parallel to the proximal Kirschner wire.
Proceed to remove the resulting portions of bone. The distal and proximal fragments are apposed, and one would employ a bone clamp to maintain reduction. Using proper AO technique, one may place two 2.0-mm cortical screws from dorsal to plantar through the proximal phalanx to achieve permanent fixation. Then the surgeon can irrigate, close and dress the site as per his or her preference.
To correct for a pathologic hallux abductus interphalangeus, as in the Akin procedure for the transverse plane correction, one would perform the second and fourth osteotomies perpendicular to the long axis of the distal phalanx whereas the third and fifth osteotomies are the same as described above.
Intraoperatively and postoperatively, we have consistently noticed increased range of motion and increased space in the first metatarsophalangeal joint on radiographs.
When it comes to postoperative weightbearing, this is determined by any proximal procedures one performs concomitantly. Without any proximal osteotomies that would contraindicate weightbearing, the patient may initially bear weight in a wooden post-op shoe. We emphasize an early, aggressive return to passive range of motion regardless of any other procedures performed. We recommend 20 minutes of passive range of motion (ROM) three times a week in the office with dressing changes prior to suture removal. We also recommend referring patients to physical therapy to facilitate passive and subsequently active range of motion with appropriate precautions.