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Marshall Solomon, DPM
Director of Podiatric Medical Education
Chairman, Department of Podiatric Medicine & Surgery
Farmington Hills, MI
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Male Speaker: Next three lectures which will bring us right up to the point of the round table section will be given by Dr. Marshall Solomon. Marshall has certainly been an educator, a man of balance and an individual who has led the profession and certainly involved in resident education. The three topics that he will share with us are the Scarf bunionectomy, hallux varus, and arthrodesis. So we’re ending with a heavy. So please welcome Dr. Marshall Solomon.
Dr. Marshall Solomon: It’s towards the end of the day and we have three subjects to cover and I’ll try to get through these quickly. If there are any questions, we’ll try to hold them to the end of each – on one of the subject matter. So we’re going to start off with the Scarf bunionectomy. A little bit about the history, it was first devised by Burutaran in ’76. Devised as Z-type osteotomy to go along with the correction of his Keller bunionectomies usually to reduce that large IM angle. Subsequently it was theorized and developed by Chuck Gudas and Zygmunt in ’83 began using a full-length horizontal Z osteotomy in the first metatarsal. Then of course, Lowell Scott Weil Sr. really popularized the osteotomy by developing modifications to the procedure itself and subsequently increasing the indications for the use of the osteotomy and so called it the Scarf bunionectomy. So essentially a scar osteotomy or bunionectomy is a carpentry term Scarf. It’s an interlocking Z osteotomy or Z cut which is inherently very stable. It offers good lateralization or transverse plane motion of the distal fragment. Because of the inherent design of the osteotomy, it provides increased stability. Subsequently, it increases the versatility because you can look at the indications and the applications of reducing IM angle. You can look at reducing PASA. And with the technique you can also plantarflex, dorsiflex, and rotate the osteotomy to some degree. So essentially the Z osteotomy or Scarf is a diaphyseal osteotomy but in actuality the horizontal cut is within the diaphysis which extends to the near proximal portion of the metaphysis. The relationship can be either 50/50 but as the modifications occurred, the more stable part is two thirds one third with the dorsal part being a little thicker than the plantar aspect. And then the arms of the Z, of the horizontal osteotomy are approximately 60 to 70 degrees from those horizontal osteotomy cut. Now, because of the nature of the osteotomy and because it extends a little bit into the near metaphysis where the base, approximately the base flares and the head flares at the neck, it can provide increased stability. So some of the benefits that we can achieve is that we can adjust the cut, either a long or short cut to accommodate fixation and I’ll talk about the concept between a long and a short Scarf bunionectomy. It can significantly reduce large intermetatarsal angles and still provide intrinsic stability. We can correct a small amount of approximately to do a set angle deformity by rotation of the capital fragment. And then by using a K wire access guide, we can plantarflex that, dorsiflex, shorten or lengthen the osteotomy to some degree.
So again, the advantages are you can medially shift the head and shaft fragment. You can shorten or lengthen. You can plantar displace, dorsal displace. You can have transverse plane rotation and some axial rotation or supination. So the indications are generally hallux valgus, hallux abducto valgus bunion deformity with an IM angle of about 13 to 18 degrees. You can have an increased PASA. It really doesn’t affect interphalangeus but proximal DASA deformity as you reduced the PASA there is some reduction in the DASA. It is effective if you have greater than 40% range of motion dorsiflexion without any severe arthrosis of the first MP joint. The counter indications are obvious. They’re usually associated with a small or less than eight degree IM angle. You certainly wouldn’t do this type of osteotomy. It’s counter indicated with IM angles larger than 20 degrees. And more importantly it’s not indicated or it’s counter indicated if you have hypermobility of the first ray especially at the metatarsal cuneiform joint and if there are arthrosis or arthritis of the first MP joint. Of course any type of osteotomy with the patient that has decreased bone density or osteoporosis is counter indicated. In summary the technique is essentially a medial incision, a lenticular capsulotomy, inter articular sesamoidal release, osteotomy with the use of a guide and we’ll explain that to you. Fixation, capsular repair, subcuticular closure and a bulky compressive dressing. So let’s go through it. First of all, the medial incision works two ways. Essentially it is a cosmetic incision that the incision is not on the dorsal aspect of the first metatarsal. This is probably more significant for women than it is for men. The importance of placement of this incision is to make sure that it is in the – if you bisect with your fingers the dorsal and plantar aspect of the metatarsal, it is about the upper third of the medial aspect of the first metatarsal. The incision is made long enough to extend from just proximal the base of the metatarsal to the base of the proximal phalanx. Now, there are major structures in these areas. It’s the neurovascular bundle. So your dissection has to be precise. You want to make sure that you’re not lacerating any vessels in or the nerve. So careful dissection which will bring you down through the superficial deep fascial layers to the medial portion of the capsule of the first metatarsal. Then there is a ventricular capsulotomy which is extends from the base of the metatarsal distillate to the base of the proximal phalanx. This incision is made through the periosteum and the capsule on to the base of the proximal phalanx. This provides us, will mention later on that it prevents disruption in postoperative arthrosis of the metatarsal through the medial approach. You can still have more than adequate exposure to do a release of the sesamoid if you have to. In fact you can do an intra-articular sesamoidal release by retracting the sesamoidal apparatus with the sesamoids plantarly from underneath the inferior aspect of the head of the metatarsal. And using a 67 or 64 blade do a lateral capsulotomy and release which helps prevent potential vascular embarrassment by going up dorsally or making a separate incision in the interspace. Now I think the key here is the use of a guide. The first part of this is to use a K-wire as an axial guide to determine if you want to neutralize shortening of the osteotomy, lengthen the osteotomy.
It lengthens the bone by osteotomy. So essentially you want to use the four five K-wire as you would do – I’ll equate this to do like a chevron or a long arm distal osteotomy. You’re going to want to line that up either with a fifth metatarsal to neutralize length or plantar flex and aim that K-wire towards the base of the fifth digit. Subsequently what you would use is a guide. This particular guide is a Reese osteotomy guide and you can then put a second K-wire into. Apply that medially and that prevents the excursion of your blade as you do your horizontal cut. Now if you look at that, there are several types of osteotomy blades and what you want to do is try to use a non-aggressive blade so you have less bone loss when you’re actually doing the osteotomy. So the horizontal cut is done through the metaphysis just to the near portions of the metaphysis at the base of the metatarsal and at the neck of the metatarsal. Next what we do is we have to then do the dorsal cut and the plantar cut, the dorsal distal which is angulated at 60 degrees and you can use a short guide for that. And also the plantar cut which is done at the proximal osteotomy. Now the one key thing is transposition of the capital fragment, laterally or lateralization of the capital fragment with the long arm. There is a tendency to have the incomplete lateralization of the osteotomy. And therefore, what happens is you have to shift the proximal portion of the osteotomy out from underneath the dorsal part and resect the portion of the proximal lateral portion of the bone mass. So you can complete lateralization to close the IM angle. That’s one of the things that you need to look for. Once that’s completed, what you want to do is you want to stabilize that with the K-wire and then proceed to fixate the osteotomy with two screws of choice. Ideally, a flat headed screw is better in respect so there won’t be as much prominence. You want to keep in mind when you’re placing those screws into the diaphysis of your osteotomy that they’re placed of course dorsally but a little bit more laterally because you’ve transposed the capital fragment and the plantar aspect of that osteotomy laterally. So that’s important to keep in mind. Then what you do is you take the redundant bone and you resect that. You proceed to capsular closure of choice. You can either do simple interrupted absorbable suture or interlocking continuous lock suture to close the capsule. Then go on to subcuticular. You close the superficial deep fascia with the absorbable suture of choice and then close the skin with a subcuticular suture or five or six O Vicryl or Polysorb. So the clinical result is good with this procedure when the procedure is selected on the right patients. You could see from the clinical result of bunion deformity with very minimal amount of shortening and a closure of the IM angle. Post-operative management. Well there’s some controversial. Some surgeons feel that they can be partial to full weight bearing immediately after surgery. Some of the old dinosaurs like to take it a little bit slower and have a little bit of non-weight bearing or protective weight bearing initially.
I don’t know if I’ve had any patients after a Scarf bunionectomy back in the shoe on a week but it can progress pretty quickly and really depends on the technique. Physical therapy is just really passive and active range of motion in the first MP joint. Those individuals that have some stiffness postoperatively then will get them into a more active physical therapy. I like to use static splinting to gain more dorsiflexion and plantarflexion as opposed to continuous passive motion devices. So let’s talk about some of the surgical pros in doing the Scarf bunionectomy. First of all, the Scarf is not a simple bunionectomy to perform. This really is a complex, really labor-intensive type of procedures. There are no shortcuts to performing this procedure. It’s very exact. So this is the type of procedure that you don’t see one, do one, and then teach one. This is you see one, you do a lot of them, and then maybe you teach one. I think the medial incision is good for cosmesis and it does give you adequate exposure. I think the ventricular capsulotomy helps prevent some postoperative restrictive range of motion. The release can be done of the sesamoid intra-articularly and this helps prevent the possibility of interruption of blood supply when you – to the metatarsal. I think the osteotomy guide and using K-wires as an access guide is key to the accuracy of your osteotomy and reduction. If you have more PASA deformity, a shorter horizontal arm maybe more beneficial but there’s a tradeoff. If you’re reducing more PASA and less IM angle, a shorter Z osteotomy Scarf is better because you don’t have as much lateral prominent bone that you have to reset. If you are trying to reduce a larger IM angle, the long horizontal cut from metaphysis to metaphysis is more critical. Though there are some questions of how much overlap of the metatarsal fragments to allow stability, some say one third. If you look at the glamoury in Weil’s article in the new glamoury he’ll say one half to two thirds. But that is really dependent on the width of the shaft of the metatarsal, the diaphysis itself. So if you have a wider metatarsal diaphysis shaft, you can move that over to a half and you can venture right into two thirds but you want to prevent troughing to occur. And then rigid internal fixation, to provide ultimate stability but will mention that you don’t want to crank on those screws either because those screws if you crank because of the design of the vertical cuts, it’s 60 to 70 degrees, can cause stress fractures proximally. So that’s something to keep in mind. Also if your osteotomy is unstable distally or the potential of troughing could occur, then using a third screw, a headless third screw from proximal to distal into the head can help stabilize the distal end of the osteotomy. Complications. Well, the biggest complication in the Scarf procedure is troughing itself up to the possibility of 35%. Stress fractures, 3%. Arthrosis and limitation in motion in the first MP joint, around 4%. Osteonecrosis is very low and there is really no difference. This is compared to other distal metatarsal bunionectomy procedures. In the literature there shows about a 6% recurrence rate and hallux varus from aggressive transposition of the osteotomy at 3% to 8%. Then of course neuritis can occur because of the medial approach of the incision.
So a couple of things that I do want to mention in summary of this is that you can reduce the stress fractures by reversing the cut, the vertical cuts on the Scarf by the distal. Instead of doing distal dorsal, you can do distal plantar and then the proximal cut. Instead of being plantar, it can be dorsal, so just reversing the Z. That shows that there’s about a 1.5% less stress fractures in that configuration of the osteotomy. A couple of some information that Weil has had in his experience is that he states that he’s had a success rate of approximately 89% to 98% with this procedure. So obviously he has a good selection criteria to have such a high success rate. You can reduce the IM angle from 4 to 10 degrees and an average 6 to 8. The hallux abducto valgus, the hallux valgus angle is reduced 15 to 19 degrees. He has limited the shortening to about one to one and a half millimeters. In the literature itself, there is approximately up to a 25% recurrence rate that he has reported. And that the difference between the long and short Z of the Scarf has to do with the balance between as I mentioned earlier the IM angle reduction and the reduction of the PASA. Okay, any questions? Great. Let’s move on.